Let's Connect Our World

Domain Name Registrations Kept Growing in 2009

2010-03-16T07:12:00.000-07:00

The Internet Domain name industry didn't have too bad of a year in 2009, even as the global economic downturn raged. According to the latest Domain Name Industry Brief from VeriSign, the total base of registered Top-Level Domain Names (TLDs) grew in 2009.

VeriSign reported that in 2009, the base of TLDs expanded by 15 million domains names to a total of 192 million domain registration across all TLDs.

Helping to the lead the way were the .com and .net TLDs, which at the end of 2009 accounted for 96.7 million domain names. The 2009 tally represents a 7 percent increase over the total number of .com and .net TLDs at the end of 2008. The company also said that that during the fourth quarter of 2009 alone, it added 7.3 million new .com and .net registrations. VeriSign manages both the .com and .net registries under contract from ICANN.

The growth isn't the only milestone for the .com domain. On March 15, VeriSign will celebrate the 25th anniversary of the first .com name -- Symbolics.com -- which was assigned in 1985.

The .com and .net domain names aren't the only ones that are growing. The total number of country code Top-Level Domains (ccTLDs) also continued to rise in 2009. In total, VeriSign reported that there were 78.6 million ccTLD at the end of 2009, an increase of 7.5 million domain names from 2008.

Overall, there are now more than 240 ccTLDs in use, with China's .cn remaining the most popular ccTLD, followed by Germany's .de and the United Kingdom's .uk.

While China has been the top ccTLD since the third quarter of 2008, the rate of growth in the .cn ccTLD has actually slowed.

"The .cn base, which had been experiencing remarkable growth as high as 467 percent year over year, slowed its growth and ended the fourth quarter with a one percent decline in its base," VeriSign's report stated.

Sitting behind all those domain names is the global DNS (define) system, which VeriSign helps to administer. As domain names have grown, so too has the load on the DNS system. VeriSign reported that during the fourth quarter of 2009, it hit peaks of 61 billion DNS queries per day. Average daily DNS query load amounted to 52 billion per day, which is an increase of 48 percent over the same period in 2008.

In 2009, VeriSign improved its DNS capabilities by way of its $100 million project Titan, an effort to improve capacity by a factor of 10.

source:http:enterprisenetworkingplanet.com

U.S. Preps Major Broadband Plan

2010-03-16T07:10:00.000-07:00

U.S. regulators will announce a major Internet policy this week to revolutionize how Americans communicate and play, proposing a dramatic increase in broadband speeds that could let people download a high-definition film in minutes instead of hours.

Dramatically increasing Internet speeds to 25 times the current average is one of the myriad goals to be unveiled in the National Broadband Plan by the the Federal Communications Commission on Tuesday.

The highly anticipated plan will make a series of recommendations to Congress and is aimed at spurring the ever-changing communications industry to bring more and faster online services to Americans as they increasingly turn to the Internet to communicate, pay monthly bills, make travel plans and be entertained by movies and music.

"This is a fairly unique event," said Paul Gallant, an analyst with Concept Capital. "The FCC really has never been asked to design a broad regulatory shift like this. Broadband is important and difficult because it threatens every established communications sector."

Some details of the plan have trickled out in the last few weeks including how to find spectrum to meet an anticipated explosion of handset devices capable of playing movies and music in addition to handling emails and voice calls.

But some carriers like AT&T Inc and Qwest Communications International Inc were irked last month when the agency's chief, Julius Genachowski, announced that the FCC would propose in the plan a goal of 100 Mbps speeds to be in place at 100 million American homes in 10 years. The current average is less than 4 Mbps.

In a sign of tension between the FCC and carriers, Qwest called it "a dream" and AT&T reacted by saying the FCC should resist calls for "extreme forms of regulation."

Since the FCC announcement, Cisco Systems Inc announced it would introduce a router that can handle Internet traffic up to 12 times faster than rival products. Google Inc has also gotten in on the hype, saying it plans to build a super-fast Internet network to show that it can be done. The FCC has praised both announcements.

The plans could also touch off tensions with television broadcasters, who will be asked to give up spectrum to wireless carriers who desperately need it for their mobile devices, such as the iPhone and Blackberry.

The FCC plans to let them share in the profits of auctions structured to redistribute the spectrum.

"We've developed a plan that is a real win-win for everyone involved and we have every expectation that it will work," Genachowski said in an interview with Reuters.

"We've certainly heard from a number of broadcasters who told us they think this is a promising direction and are getting ready to roll up their sleeves with us," he said.

The FCC also wants to make sure that anchor institutions -- government buildings, schools, libraries and healthcare facilities -- get speeds of about 1 gigabit per second by 2020.

The full broadband plan is expected to be released at a Tuesday meeting among the FCC's five members who are expected to discuss the results and recommendations of the roadmap, which was mandated by Congress. Congress may have to pass legislation to enact some portions of the plan.

FCC officials have said some of the goals are aspirational and should be viewed as a "living, breathing" document for the next decade in hopes of helping 93 million Americans without broadband get connected.

Achievable

"It is both aspiration and achievable," Genachowski said.

The Obama administration has touted the plan as a way to create jobs and make energy use more efficient.

"It will be a call to action," said Blair Levin, who heads the FCC's broadband task force which has collected data and comments from the industry, academics and the public as well as from three dozen public workshops.

The FCC has placed most of its attention on broadband policy which Darrell West, director of governance studies at the Brookings Institution, called "the signature issue" since Genachowski took over the helm in late June.

"It means that broadband is going to drive other types of policy decisions and it really sets the parameters for telecommunications and new applications," West said.

FCC officials have said that the plan will not take sides on technology or applications, but they want to lay the groundwork to spur innovation and job creation.

Officials have said the plan will ask Congress to fund up to $16 billion to build an emergency public safety system.

It would also tell lawmakers that a one-time injection of $9 billion could accelerate broadband reach to the 4 percent of Americans who do have access. Otherwise they could let the FCC carry out a 10-year plan to realign an $8 billion U.S. subsidy program for universal broadband access instead of universal phone access.

Experts call the plan ambitious but question if the FCC, which plans to spin off a series of rule-making proposals linked to the plan, can realistically make good on its recommendations.

"There's so little progress on this stuff in Washington," said Rob Atkinson, who heads the Information Technology and Innovation Foundation.

"I think Chairman Genachowski has a real opportunity to bring different warring interests under 50-75 percent of the plan."

Copyright 2010 Reuters
source:internetnews.com

iPad, Apple Computer Tablet Worth USD $ 4 Million

2010-01-29T04:12:00.000-08:00

Newer Gadget of the most anticipated Apple finally appeared. iPad, thus the name of the Apple tablet computer. Apple CEO Steve Jobs introduced the waterfall itself to the device for U.S. $ 499 or about USD 4 million of this.

Yes, this is one of the surprise of the presence iPad. Therefore, previous analysts have cautioned that this gadget will be sold in the range of U.S. $ 1000.

However, Apple seems quite sensitive to the economic recession which is still hanging, so it does not fix the price that was too expensive for the new champ.

Even so, iPad USD 4 million is for the lowest version, which has Wi-Fi connectivity and solid state 16 GB of memory. While for the most expensive version of others, equipped with 3G connectivity and 64 GB of memory dibanderol U.S. $ 829.

If you view the Jobs of the explanation, seem more iPad intended as an entertainment device rather than to work. Because the reader can be used for electronic (e-reader), gaming, surf the Internet to watching videos.

"We want to start the year 2010 by introducing a revolutionary device," Jobs said, quoted from Reuters (28/1/2010).

Interested in direct purchase? Patient first. Therefore, the new Apple iPad planning to dump into the market within the next two months.

source:detikinet.com

Internet Protocol

2010-01-26T05:11:00.000-08:00

The Internet Protocol (IP) is a protocol used for communicating data across a packet-switched internetwork using the Internet Protocol Suite, also referred to as TCP/IP.

IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering distinguished protocol datagrams (packets) from the source host to the destination host solely based on their addresses. For this purpose the Internet Protocol defines addressing methods and structures for datagram encapsulation. The first major version of addressing structure, now referred to as Internet Protocol Version 4 (IPv4) is still the dominant protocol of the Internet, although the successor, Internet Protocol Version 6 (IPv6) is being deployed actively worldwide.

IP encapsulation

Data from an upper layer protocol is encapsulated as packets/datagrams (the terms are basically synonymous in IP). Circuit setup is not needed before a host may send packets to another host that it has previously not communicated with (a characteristic of packet-switched networks), thus IP is a connectionless protocol. This is in contrast to public switched telephone networks that require the setup of a circuit for each phone call (connection-oriented protocol).

Services provided by IP

Because of the abstraction provided by encapsulation, IP can be used over a heterogeneous network, i.e., a network connecting computers may consist of a combination of Ethernet, ATM, FDDI, Wi-Fi, token ring, or others. Each link layer implementation may have its own method of addressing (or possibly the complete lack of it), with a corresponding need to resolve IP addresses to data link addresses. This address resolution is handled by the Address Resolution Protocol (ARP) for IPv4 and Neighbor Discovery Protocol (NDP) for IPv6.

Reliability

The design principles of the Internet protocols assume that the network infrastructure is inherently unreliable at any single network element or transmission medium and that it is dynamic in terms of availability of links and nodes. No central monitoring or performance measurement facility exists that tracks or maintains the state of the network. For the benefit of reducing network complexity, the intelligence in the network is purposely mostly located in the end nodes of each data transmission, cf. end-to-end principle. Routers in the transmission path simply forward packets to next known local gateway matching the routing prefix for the destination address.

As a consequence of this design, the Internet Protocol only provides best effort delivery and its service can also be characterized as unreliable. In network architectural language it is a connection-less protocol, in contrast to so-called connection-oriented modes of transmission. The lack of reliability allows any of the following fault events to occur:

data corruption
lost data packets
duplicate arrival
out-of-order packet delivery; meaning, if packet 'A' is sent before packet 'B', packet 'B' may arrive before packet 'A'. Since routing is dynamic and there is no memory in the network about the path of prior packets, it is possible that the first packet sent takes a longer path to its destination.

The only assistance that the Internet Protocol provides in Version 4 (IPv4) is to ensure that the IP packet header is error-free through computation of a checksum at the routing nodes. This has the side-effect of discarding packets with bad headers on the spot. In this case no notification is required to be sent to either end node, although a facility exists in the Internet Control Message Protocol (ICMP) to do so.

IPv6, on the other hand, has abandoned the use of IP header checksums for the benefit of rapid forwarding through routing elements in the network.

The resolution or correction of any of these reliability issues is the responsibility of an upper layer protocol. For example, to ensure in-order delivery the upper layer may have to cache data until it can be passed to the application.

In addition to issues of reliability, this dynamic nature and the diversity of the Internet and its components provide no guarantee that any particular path is actually capable of, or suitable for performing the data transmission requested, even if the path is available and reliable. One of the technical constraints is the size of data packets allowed on a given link. An application must assure that it uses proper transmission characteristics. Some of this responsibility lies also in the upper layer protocols between application and IP. Facilities exist to examine the maximum transmission unit (MTU) size of the local link, as well as for the entire projected path to the destination when using IPv6. The IPv4 internetworking layer has the capability to automatically fragment the original datagram into smaller units for transmission. In this case, IP does provide re-ordering of fragments delivered out-of-order.

Transmission Control Protocol (TCP) is an example of a protocol that will adjust its segment size to be smaller than the MTU. User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) disregard MTU size thereby forcing IP to fragment oversized datagrams.

IP addressing and routing

Perhaps the most complex aspects of IP are IP addressing and routing. Addressing refers to how end hosts become assigned IP addresses and how subnetworks of IP host addresses are divided and grouped together. IP routing is performed by all hosts, but most importantly by internetwork routers, which typically use either interior gateway protocols (IGPs) or external gateway protocols (EGPs) to help make IP datagram forwarding decisions across IP connected networks

How broadband satellite Internet works

2010-01-18T06:26:00.000-08:00

Satellites have brought Internet access to places where IP communications seemed impossible. In this section, we explain how satellite Internet works. You will understand how bytes of information or simply a mouse click travels all the way from your computer to the satellite, to our NOC and back.

VSAT Systems uses commercial satellite connections as a high-speed digital link between our customers and the U.S. Internet backbone. The main components of a satellite system comprises of the following:

1. Ground-based electronic equipment

The VSAT dish: It refers to what most people call their dish. VSAT units are two-way satellite ground stations with dishes that typically range from 0.75m to 1.8m in diameter. VSAT Systems offers VSAT antennas between 1.2m and 2.4m in diameter, depending on the application and location.
The indoor modem: A satellite modem facilitates data transfers using a communications satellite as a relay. VSAT Systems end users typically use the iDirect 3100 series Modem.
The teleports: The teleport is the earth station that controls communications across the space link. The teleport is the heart of the VSAT Systems satellite Internet system. VSAT Systems has three 6.3m VertexRSI antennae, transmitters, control systems, redundant links to the Internet, plus auxiliary power and HVAC.
The Network Operations Center (NOC): The facility which controls all communications over the satellite link. The NOC monitors for power failures, satellite signal issues and other performance issues that may affect the network. The VSAT Systems NOC is located in Akron, Ohio.

2. Satellite equipment

The satellite: In a geostationary or geosynchronous orbit 22,236 miles above the earth’s surface, a satellite completes one revolution in exactly the same amount of time that it takes the Earth to rotate one full turn on its axis. Thus, the satellite always appears at the same position above the Earth. This eliminates the need for satellite dishes at the user location to track the satellite, which greatly simplifies their construction and cost. These satellites, used for a variety of purposes like broacast and telecommunications, can also be used to provide Internet access at any location on Earth.
Transponder space segment: The communications channels on a satellite that both receive and retransmit data. Modern satellites carry between 36 and 72 separate transponders all running at different frequencies. These frequency segments are used for transmission of data.
Internet Backbone: The backbone is a large collection of interconnected, high-capacity, commercial, government, and academic data routes and core routers that carry data. They connect with other countries and continents around the world.

3. Here’s how the process works - in 5 easy to understand steps:

End user computer is connected to your network, which in turn is connected to the Internet by VSAT Systems. You open a web browser, and type in a web address. End user computer sends a request for a transfer of data - both transmit and receive.
That request is sent from the end user PC, through their home network, to the indoor satellite modem which modulates the signal and passes it to the VSAT dish. The VSAT dish converts this signal to an RF signal and sends it to a satellite located in the geostationary orbit at the speed of light - 186,000 miles per second.
The satellite in the geo-stationary orbit receives this signal and sends it to one of the VSAT Systems teleports in Akron, Ohio. This illustrates the fact that although the packets of information travel tremendous distances via the space segment, the packets hop fewer networks due to the large reduction in the number of inter domain and intra domain routers giving an opportunity to minimize latency.
The request then goes to VSAT Systems’ NOC, which retrieves the requested website from the web server, across the U.S. Internet backbone.
The whole cycle is then reversed and the requested data is available to the user. A 90,000 mile journey, through millions of dollars of infrastructure and sophisticated equipment, all in less than 700 milliseconds.

CES: The coolest laptops of 2010's show

2010-01-16T04:19:00.000-08:00

LAS VEGAS--We saw dozens of new laptop models at CES this year, and though the vast majority of them were next-step upgrades of existing models, there were a handful that really grabbed our attention, either because they brought something new to the game, or because they were excellent examples of their category.

We've already rounded up the various slate/tablet devices, so we'll concentrate on traditional laptop-shaped systems (although we'll make an exception for the Lenovo U1 Hybrid, which docks its tablet screen to become a standard Windows 7 machine).

Verizon looks for more revenue in wireless data

2010-01-14T07:23:00.000-08:00

Verizon Wireless, the nation's largest wireless provider, is reportedly revamping its existing wireless data prices and is considering implementing a usage-based billing model for its upcoming 4G wireless services as it tries to squeeze out more revenue from wireless data services.

Starting January 18, Verizon is expected to tweak its wireless data plan for what it considers its "3G multimedia" phones so that subscribers will pay the same price as customers using a smartphone. The news of the new pricing rates was reported Wednesday by the blog Broadband Reports, which obtained internal documents about the changes from a Verizon employee.

A Verizon Wireless spokeswoman declined to comment on the new pricing plan.

The news comes just a few days after Verizon Wireless' chief technology officer Dick Lynch was quoted by The Washington Post saying that the wireless operator is also considering implementing usage-based billing for services it will soon introduce on its upcoming 4G wireless network.

These two pieces of news suggest that Verizon Wireless is looking to find the sweet spot in wireless data pricing. As the company's revenue base shifts toward data and away from voice services, Verizon and other wireless operators are looking carefully at how best to maximize their profitability.

It's no secret that prices for mobile voice services are dropping. And as a result, phone companies are competing more aggressively on price. A few months ago Sprint Nextel announced its Any Mobile, Anytime plan that allows subscribers to call any cell phone in the U.S. regardless of carrier for $69.99 a month.

Earlier this week, MetroPCS, a smaller regional operator targeting the prepaid phone market, lowered the price of its service, undercutting similar plans from other prepaid providers, such as Sprint's Boost Mobile. This new offering will include all taxes and fees for plans that range between $40 and $60 a month.

Clearly, a price war is emerging on voice services.

Meanwhile, operators are trying to squeeze more revenue out of their data services. This is likely why Verizon is looking at increasing the price of its data plans for mid-tier, non-smartphone devices and why it is thinking hard about going with a usage-based model for its 4G wireless network, rather than offering an all-you-can-eat plan.

According to Broadband Reports, Verizon Wireless is planning to force nearly every subscriber to sign up for a data plan. Even customers using its basic "simple feature" phones will be required to have a data plan. And soon all subscribers signing up for a multimedia device will be required to sign up for a data plan. Up to this point, only certain multimedia phones, such as the Samsung Rogue, have required a data plan. And customers with smartphones have already been required to get data plans.

Starting January 18, the data plans for all non-smartphones will change, Broadband Reports said.

Last year, Verizon changed its non-smartphone data plans to offer multimedia phone subscribers two options for data service. They could either subscribe to a $9.99 that offered 25 megabtyes of data with a charge of $0.50 charged for each additional megabyte over the maximum, or they could subscribe to a $19.99 per month plan that offered 75MB with a $0.30 charge for each MB over the cap.

Broadband Reports says the new pricing model will increase the price of the top plan to $29.99 a month. In exchange for the higher price, subscribers will reportedly be given unlimited access to data. This tier of service will also include mobile e-mail service.

Meanwhile, customers opting for the $9.99 plan will still get the 25MB usage cap, but they will be charged $0.20 for each megabyte over the cap instead of $0.30 per megabyte, the blog said.

Verizon Wireless CTO, Dick Lynch
(Credit: Verizon )

This change essentially offers the same all-you-can-eat plan for multimedia phone subscribers that it requires its smartphone customers to buy.

For some heavy-data users this will be a great deal. But for most consumers, it's likely overkill. Most multimedia phone subscribers only use between 25MB and 100MB of data per month, according to Broadband Reports. The 25MB plan may be too little for these customers, but an unlimited plan offers much more than what many consumers need.

And this excess capacity costs consumers.

The business strategy is very similar to how gyms, like the New York Sports Club, make money. For $89 a month, someone can get a full membership to the gym with access day or night at any location. Some people will use their memberships to the fullest, working out seven days a week and using multiple gym locations throughout the week.

But many will go to the gym much less regularly, and they will never go to a facility other than the one where they originally joined as a member. And yet each member pays the same amount every month, regardless of how much they use their membership.

This billing method works out well for companies when many customers use a fraction of the resources available. But when the majority actually go to the gym regularly or access wireless data services, in the case of wireless operators, then these businesses start to lose money, because they have to invest more in infrastructure.

When this happens, a usage-based billing model is more advantageous to the business.

The switch to usage-based billing
This is exactly the model that Verizon plans to switch to when it completes its 4G wireless network. Lynch told the Washington Post last week that it's very likely that Verizon will do away with flat rate pricing when it rolls out its 4G wireless and will instead charge customers based on how much bandwidth they use.

"The problem we have today with flat-based usage is that you are trying to encourage customers to be efficient in use and applications but you are getting some people who are bandwidth hogs using gigabytes a month and they are paying something like megabytes a month," Lynch told the Post. "That isn't long-term sustainable. Why should customers using an average amount of bandwidth be subsidizing bandwidth hogs?"

AT&T is seeing the effects of this problem with the popular Apple iPhone. AT&T reports that its iPhone users consume more data than other 3G wireless customers. This has resulted in strains on the network. And now iPhone users are complaining about poor service, especially in urban areas where iPhone usage is high.

AT&T's head of wireless Ralph de la Vega said last year that AT&T needs to come up with a different way to price its service to incentivize customers to use less data.

Usage-based billing, or asking subscribers to pay for what they use, has increasingly been seen by executives as the answer to this problem. And now the idea has support from the two Republican Federal Communications Commission commissioners, Robert McDowell and Meredith Attwell Baker.

McDowell said during a public appearance at the CES tradeshow last weekend that wireless companies should be able to experiment with different pricing models, according to the The Hill, a blog covering Capitol Hill. He said that allowing an all-you-can eat model to persist will lead to gridlock on the wireless Internet.

Baker agreed and even suggested that people may soon have to pay for "roaming."

So what does all this mean for consumers? Well, in the short term, it means many Verizon Wireless customers are likely to pay more for more service than they actually need. And in the future, 4G wireless subscribers are likely to pay more for services they actually use. Don't expect any great bargains in wireless data now or in the future. In either case, Verizon and other wireless operators will make sure they can get as much money as they can from the increasing number of people who subscribe to their data services.

source:cnet.com

'Apple Tablet It Real'

2010-01-13T04:48:00.000-08:00

Apple Tablet news presence is not just fairytales. One of the French telecommunications operator, Orange has confirmed the truth about the news.

Stephane Richard, as one executive of Orange, as quoted from Techtree, Wednesday (13/1/2010) confirmed that the Apple Tablet soon be attending. In an interview, one French television he reveals that these devices Apple would soon be present at the end of this month.

In addition, Richard also added that the Apple Tablet will be equipped with a webcam. He also mentioned that Orange customers will soon be able to sample Apple's new device is.

As mentioned on the detailed specifications and prices offered Richard concluded soon. This makes the curiosity of Apple fans around the world

Windows Mobile 7 Coming in Cellular Industry Party?

2010-01-13T04:46:00.000-08:00

Many people think Microsoft will introduce Windows Mobile 7 at CES 2010. But the reality is not. Microsoft's desktop instead discuss issues and their Christmas project.

Now the rumors that Microsoft's new mobile OS is about to appear at the Mobile World Congress (MWC) in 2010 which is a huge party scheduled for the mobile industry and in the second week of February next. The source of the quoted zdnet, Tuesday (12/1/2010), said that the introduction of Windows Mobile 7 on the upcoming MWC is not just a mere rumor.

Robbie Bach, president of Microsoft Entertainment & Devices Division at zdnet interviewed said that the MWC later, the public was able to meet with the Windows Mobile 7. Although not yet clear, whether this is a form of release, the public would be the first impression about the latest mobile OS on the prestigious event.

Robbie Bach also confirmed that the OS is not just evolution, but also be more 'friendly' with its users, from the previous Windows Mobile versions that seem intended for businessmen only.

Let's see, if the rumors introduction of Windows Mobile 7 in the MWC held next month's going to happen?

source:detikinet

Phone 4G came out in April?

2010-01-13T04:42:00.000-08:00

The rumors about the presence of a fourth-generation iPhone beginning was widely blow. Rumored that Apple's smartphone is besutan sauntered in April this year.

Rumor is then peppered with various predictions. There was a mention that this latest generation iPhone will have dual core processors.

Quoted from Appleinsider, Wednesday (13/1/2010), reported also that there will be increasing the quality of graphics, video chat, screen organic light-emitting diode (OLED), a more capable camera and a battery that is easily changed in this fourth-generation iPhone .

It added that Apple and Korea Telecom - the exclusive iPhone providers in South Korea - has made an agreement to introduce the latest iPhone models as soon as possible in South Korea.

Previous rumors about the fourth generation iPhone was never rose in the year 2009. China claims a company to take part in making these devices and claim to have had the components for the iPhone was this brand.

Supplier companies named China OnTrade it offers on the internet that claimed the case would eventually be a component of the iPhone 4G

source:detikinet

By Rev. B, 1 Giga Download Just 11 Minutes

2010-01-11T04:05:00.000-08:00

Bali - Access broadband networks using CDMA technology, Rev. B, to download (downloading) data files for 1 Gb of internet transfer takes only eleven minutes.

So the demo that was held at Smart Telecom launched the first CDMA service network using the latest technologies supplied Rev. B vendor Qualcomm and ZTE.

"Consumers will feel the real speed of these incredible," claims Head of Core Product and Branding Smart, Ruby Hermanto, while demonstrating the CDMA EVDO Rev B at Hotel Discovery, Bali, on Sunday night (10/1/2010).

Although able to download 1 GB of files in just 11 minutes, but the original speed will no doubt will come down drastically so many users who use the service simultaneously in a single point of network base stations (BTS).

Smart claimed could bring a maximum speed of 9.3 Mbps for data download and upload to 5.4 Mbps (upload). Ruby said, this year will increase again Smart network capacity in the canal Rev. B. "We are upgrading our network again to Rev B download speeds up to 14.7 Mbps can," he said without going to mention how many base stations to be upgraded.

CDMA-based service was held Smart at 1900 MHz frequency band. This mobile operators do not want to mention the number of channels used by a total of five canals had.

Currently, Rev. B new service was held in Bali. It was only in some places. "Just 60% of our base stations 48 in Bali," said President Director of Smart, Sutikno Widjaja.

According to him, the whole area of the new Bali will be served all at the end of this first quarter of 2010. After Bali, Smart plans to expand coverage to Rev. B 32 cities that previously had been spread Rev A until the end of year.

To enjoy the service EVDO Rev B via a modem ZTE offers, customers will be charged Smart mortgage USD 450 thousand per month for 12 months. These costs include the cost of unlimited access for a year.

source:http://www.detikinet.com/read/2010/01/11/074212/1275427/328/dengan-rev-b-unduh-1-giga-cuma-11-menit?topnews

CDMA EVDO Rev B World First Commercial in Bali

2010-01-11T04:03:00.000-08:00

Bali - broadband internet network of technology-based Code Division Multiple Access (CDMA) Evolution Data Only (EVDO) Rev B has a commercial presence for the first time in the world through Bali, Indonesia.

The service is organized by the CDMA cellular operator Smart Telecom is using the base station (BTS) from China's ZTE and Qualcomm's chipset technology from the United States.

"We deliberately choose Bali as the first launch of EVDO Rev B because Bali is the gateway to the world Indonesia internationally," said President Director of Smart Sutikno Widjaja, the launch of the Rev B at Hotel Discovery, Bali, on Sunday night (10/1/2010).

EVDO Rev B is a development of EVDO Rev A network that offers a maximum speed of 9.3 Mbps for downloading data (downloading) and 5.4 Mbps for upload (upload).

Through EVDO Rev A network is also held Smart, the maximum speed offered by Franky Widjaja owned company that until only 3.8 Mbps for downloading and 1.8 for uploads.

"With Rev. B, our broadband internet so much faster than tripled Rev A," said Head of Core Product and Branding Smart, Ruby Hermanto.

Currently, Rev. B new service was held in Bali. It was only in some places. "Just 60% of our base stations 48 in Bali," said Sutikno. According to him, the whole area of the new Bali will be served all at the end of this first quarter of 2010.

After Bali, Smart plans to expand coverage to Rev. B 32 cities that previously had been spread Rev A until the end of year. But unfortunately, both Sutikno and Ruby did not want to reveal how many base stations are ready to be upgraded and the total value of issued investment.

Smart itself allows customers to seek their own purchases Rev B-capable modem in the free market to be able to access the latest broadband networks this.

However, if customers buy through Smart, modem ZTE Rev. B output dipasarkannya the price of Rp 450 thousand per month for a year. This purchase cost includes the cost of unlimited access for a year.

"With a total of Rp 5.4 million a year, a modem which we offer, including inexpensive. For the original price Rev. B modem is still expensive, U.S. $ 600 or nearly USD 6 million," explained Tom Alamas Dinharsa, Division Head of Device Technology and Special Project.

source:http://www.detikinet.com/read/2010/01/11/071259/1275411/328/cdma-evdo-rev-b-pertama-dunia-komersil-di-bali?topnews

Review Modem:Sierra Wireless Overdrive 3G/4G

2010-01-09T07:46:00.000-08:00

Available Jan. 10 exclusively from Sprint, Overdrive is the nation's first 3G/4G Mobile Hotspot, allowing multiple Wi-Fi-enabled devices to share a connection to Sprint's 4G network

OVERLAND PARK, Kan., Jan 06, 2010 -- Sprint announced today the upcoming availability of Overdrive 3G/4G Mobile Hotspot (aka the Sierra Wireless AirCard W801). Overdrive allows you to connect up to five Wi-Fi-enabled devices simultaneously--including laptops, gaming devices, cameras and even smartphones from other carriers--through a single connection (via Wi-Fi), to a network that is up to 10 times faster than today's 3G speeds from any national wireless carrier.1 There's no need to wait for 4G devices to enjoy the benefits of 4G: Overdrive creates a connection between the Sprint 4G network and virtually all of the hundreds of millions of Wi-Fi-enabled electronics devices owned by or available to customers today.

"This device delivers the connected lifestyle to our customers in overdrive," said Dan Hesse, Sprint CEO. "The fact that it connects up to five Wi-Fi-enabled devices is especially meaningful because at 4G speeds, customers can download and upload more data--gigabytes, not megabytes--in a matter of seconds. The Overdrive on the 4G network is made for the multitude of bandwidth-hungry applications customers want to access wirelessly, like video streaming. 4G beats 3G for speed and for value."

Overdrive 3G/4G Mobile Hotspot will benefit customers today

In the home:

Through a single connection, you can bypass your cable provider and stream HD movies from content distribution providers (such as Netflix, Amazon and Blockbuster) right to your TV; connect your Xbox 360 and game real-time with someone located across the globe; move pictures wirelessly from your camera to a digital picture frame and surf the Web on your laptop while streaming Pandora.

In the dorm:

Connect virtually anywhere on a campus with 4G coverage at 4G speeds: Turn your iPod Touch with Skype into a voice phone and make a call, or stream a live movie from Hulu or Netflix to your laptop.

On-the-go:

Whether you're on a long trip or running a busy day of errands, use Overdrive to keep passengers entertained in the car.2 Stream your favorite TV show from Hulu to your Netbook; use a PSP gaming device to access multiple games and content; download music to your Zune HD; and turn your 3G iPhone into a 4G device. It's all very simple with Overdrive.

Mobile office:

Join a video conference, download large files, conduct a virtual home tour and stay in constant contact with your office via unified communications.

Move Overdrive 3G/4G Mobile Hotspot to the workplace and the benefits are even greater with enhanced Wi-Fi performance, increased productivity and improved cost savings. Set up and redeploy easily and quickly for a small workgroup; back-up or replace costly wireline connections to small branches, retail locations or home offices; cost-effectively share one connection on one plan when mobile with other employees and customers; use as excellent "power up and go" mobile solution to maintain connectivity for business/emergency continuity; and easily perform multiple functions with constant connectivity and real-time access to corporate data.

"At Best Buy, we see an amazing amount of new devices and products from mobile phones to televisions to gaming consoles that are designed to connect and interact with each other. This kind of connectivity is very exciting, but it can also be complicated to maximize unless you actually see it and understand it," said Brian Dunn, Best Buy CEO. "In combination with Best Buy's skilled and passionate associates, the Sprint Overdrive will allow us to showcase our in-store experience by demonstrating how various Wi-Fi- enabled products work and connect together, whether in the home, on-the-go or both."

As the first dual-mode device of its kind, Overdrive 3G/4G Mobile Hotspot can be used on both the Sprint 4G network and Sprint's Mobile Broadband Network, America's most dependable 3G network.3 This flexibility allows customers to enjoy 4G performance in any Sprint 4G market or to use Sprint's reliable 3G mobile broadband network when outside a 4G area. Sprint 4G is already available in 27 markets and continues to expand to new cities, bringing wireless speeds up to 10 times faster than today's 3G from any other national wireless carrier.

"Sierra Wireless places a high priority on making our products simple to use, and we have put considerable time and effort into ensuring that Overdrive3G/4G Mobile Hotspotdelivers the easiest user experience of any mobile hotspot on the market," said Jason Cohenour, CEO of Sierra Wireless. "Its simplicity, combined with its compact portability, and security, makes Overdrive3G/4G Mobile Hotspotideal for both personal and business use in a variety of situations."

Key features of Overdrive 3G/4G Mobile Hotspot include a LCD that provides important information such as battery life and internet connection status, as well as an easy-to-use web interface for customizing settings. Overdrive 3G/4G Mobile Hotspot also includes built-in GPS capability (on 3G), MicroSD slot for up to 16 GB memory cards creating shared storage with up to five connected devices, and an extended Wi-Fi range of up to 150 feet.

Beginning on Jan. 10, customers will be able to purchase Overdrive 3G/4G Mobile Hotspot exclusively from Sprint for $99.99 (excluding taxes) after a $50 mail-in-rebate with a two-year service agreement. Customers can purchase the device and sign up for 3G/4G plans at select Sprint retail stores and select Best Buy stores; available through business sales, Web (www.sprint.com) and Telesales (1-800-SPRINT1) in coming weeks. Also beginning Jan. 10, Sprint will offer simplified 3G/4G data plans for consumers and businesses at $59.99 monthly (price plans exclude surcharges and taxes).4

Sprint continues to blaze trails with 4G

Sprint is the first national wireless carrier to test, launch and market 4G technology. (View 4G coverage at www.sprint.com/4G)

Sprint made history by launching 4G in Baltimore in September 2008. Sprint currently offers 4G service in 27 markets, including Atlanta, Baltimore, Chicago, Dallas/Ft. Worth, Las Vegas, Philadelphia, Portland, Ore., San Antonio and Seattle. Sprint 4G is also offered in Abilene, Texas; Amarillo, Texas; Austin, Texas; Bellingham, Wash.; Boise, Idaho; Charlotte, N.C.; Corpus Christi, Texas; Greensboro, N.C. (along with High Point and Winston-Salem); Honolulu; Killeen/Temple, Texas; Lubbock, Texas; Maui, Hawaii; Midland/Odessa, Texas; Milledgeville, Ga.; Raleigh, N.C. (along with Cary, Chapel Hill and Durham); Salem, Ore.; Waco, Texas and Wichita Falls, Texas.

In 2010, Sprint expects to launch service in multiple markets, including Boston, Houston, New York, San Francisco and Washington, D.C.

Sprint is harnessing the power of 4G as the majority shareholder of Clearwire, the independent company that is building the WiMAX network.

"Up to 10x faster" based on download speed comparison of 3G's 600 kbps vs. 4G's 6 Mbps. Typical published 3G avg. speeds (600 kbps-1.7 Mbps); 4G avg. speeds (3-6 Mbps). Actual speeds may vary. 4G currently available in select areas /devices; check Sprint.com/4G for Sprint 4G coverage/device info.
Sprint encourages all wireless users to drive responsibly and avoid distractions.
"Dependable" based on independent, third-party drive tests for 3G data connection success, session reliability, and signal strength for the top 50 most populous US markets (including PR) from January 2008 to August 2009. Not all services available on 3G and coverage may default to separate network when 3G unavailable.
Sprint reserves the right, at our sole discretion to deny, terminate, modify, disconnect or suspend service if customer exceeds the off-network roaming threshold (300MB/mo.) or engages in the following prohibited uses: server devices or host computer applications, including, but not limited to, disproportionate Web camera posts or broadcasts, automatic data feeds, automated machine-to-machine connections, peer-to-peer (P2P) file-sharing applications broadcast to multiple servers or recipients such that they could enable "bots" or similar routines, or for any other reason that, in our sole discretion harms our network.

Nokia Trial 4G Modem

2010-01-09T07:39:00.000-08:00

Nokia has revealed its first Internet modem supporting Long Term Evolution (LTE) technology. LTE is generally marketed as 4G, since it is the last step toward the 4th generation of radio technologies designed for mobile networks. It is a set of enhancements to the Universal Mobile Telecommunications System (UTMS) to be introduced in 3GPP Release 8.

Nokia's Internet Modem RD-3 supports interoperability with GSM/EDGE and WCDMA/HSPA to make the most out of the global GSM and WCDMA reach right from the start. "Nokia is committed to supporting industry activities aimed at maturing LTE technology to enable the first commercial networks to launch in 2010," says Jani Mäenpää, Project Manager, LTE/SAE Interoperability and Trials, Nokia.

He continued: "Nokia is a founding member in the LTE/SAE Trial Initiative (LSTI) and carries out interoperability testing with a number of network vendors, collaborates with measurement equipment manufacturers and is ready to support operators with their LTE deployment activities. The Nokia Internet Modem RD-3 is used in all these activities."

LTE is considered a major step in the direction of providing wireless IP-based real-time multimedia services for consumers, providing the benchmark for high data rates and low response times. It has the potential to offer a rich broadband Internet experience when a fixed line connection is not available, and is an enormous improvement over today's current mobile broadband products.

4G

2010-01-09T05:53:00.000-08:00

4G refers to the fourth generation of cellular wireless standards. It is a successor to 3G and 2G standards, with the aim to provide a wide range of data rates up to ultra-broadband (gigabit-speed) Internet access to mobile as well as stationary users. Although 4G is a broad term that has had several different and more vague definitions, this article uses 4G to refer to IMT Advanced (International Mobile Telecommunications Advanced), as defined by ITU-R.
A 4G cellular system must have target peak data rates of up to approximately 100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility such as nomadic/local wireless access, according to the ITU requirements. Scalable bandwidths up to at least 40 MHz should be provided.A 4G system is expected to provide a comprehensive and secure all-IP based solution where facilities such as IP telephony, ultra-broadband Internet access, gaming services and HDTV streamed multimedia may be provided to users.[citation needed]

The pre-4G technology 3GPP Long Term Evolution (LTE) is often branded "4G", but the first LTE release does not fully comply with the IMT-Advanced requirements. LTE has a theoretical net bitrate capacity of up to 100 Mbit/s in the downlink and 50 Mbit/s in the uplink if a 20 MHz channel is used - and more if Multiple-input multiple-output (MIMO), i.e. antenna arrays, are used. Most major mobile carriers in the United States and several worldwide carriers have announced plans to convert their networks to LTE beginning in 2009. The world's first publicly available LTE-service was opened in the two Scandinavian capitals Stockholm and Oslo on the 14 December 2009, and branded 4G. The physical radio interface was at an early stage named High Speed OFDM Packet Access (HSOPA), now named Evolved UMTS Terrestrial Radio Access (E-UTRA).

LTE Advanced (Long-term-evolution Advanced) is a candidate for IMT-Advanced standard, formally submitted by the 3GPP organization to ITU-T in the fall 2009, and expected to be released in 2011. The target of 3GPP LTE Advanced is to reach and surpass the ITU requirements. LTE Advanced should be compatible with first release LTE equipment, and should share frequency bands with first release LTE.

The Mobile WiMAX (IEEE 802.16e-2005) mobile wireless broadband access (MWBA) standard is sometimes branded 4G, and offers peak data rates of 128 Mbit/s downlink and 56 Mbit/s uplink over 20 MHz wide channels. The IEEE 802.16m evolution of 802.16e is under development, with the objective to fulfill the IMT-Advanced criteria of 1000 Mbit/s for stationary reception and 100 Mbit/s for mobile reception.

UMB (Ultra Mobile Broadband) was the brand name for a discontinued 4G project within the 3GPP2 standardization group to improve the CDMA2000 mobile phone standard for next generation applications and requirements. In November 2008, Qualcomm, UMB's lead sponsor, announced it was ending development of the technology, favouring LTE instead.[5] The objective was to achieve data speeds over 275 Mbit/s downstream and over 75 Mbit/s upstream.

In all these suggestions for 4G, the CDMA spread spectrum radio technology used in 3G systems and IS-95 is abandoned and replaced by frequency-domain equalization schemes, for example multi-carrier transmission such as OFDMA. This is combined with MIMO (i.e. multiple antennas(Multiple In Multiple Out)), dynamic channel allocation and channel-dependent scheduling.

Objectives

4G is being developed to accommodate the QoS and rate requirements set by further development of existing 3G applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, but also new services like HDTV content, minimal services like voice and data, and other services that utilize bandwidth. It may be allow roaming with wireless local area networks, and be combined with digital video broadcasting systems.

The 4G working group[clarification needed] has defined the following as objectives of the 4G wireless communication standard:

Flexible channel bandwidth, between 5 and 20 MHz, optionally up to 40 MHz.[2]
A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R,
A data rate of at least 100 Mbit/s between any two points in the world,
Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink (meaning that 1000 Mbit/s in the downlink should be possible over less than 67 MHz bandwidth)
System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell for indoor usage.
Smooth handoff across heterogeneous networks,
Seamless connectivity and global roaming across multiple networks,
High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)
Interoperability with existing wireless standards,and
An all IP, packet switched network.

Approaches

As described in 4G consortia including WINNER, WINNER - Towards Ubiquitous Wireless Access, and WWRF, a key technology based approach is summarized as follows, where Wireless-World-INitiative-NEw-Radio (WINNER) is a consortium to enhance mobile communication systems.

Consideration points

Coverage, radio environment, spectrum, services, business models and deployment types, users.

Principal technologies

* Physical layer transmission techniques[12]
o No CDMA.
o MIMO: To attain ultra high spectral efficiency by means of spatial processing including multi-antenna and multi-user MIMO
o Frequency-domain-equalization, for example Multi-carrier modulation (OFDM) or single-carrier frequency-domain-equalization (SC-FDE) in the downlink: To exploit the frequency selective channel property without complex equalization.
o Frequency-domain staistical multiplexing, for example (OFDMA) or (Single-carrier FDMA) (SC-FDMA, a.k.a. Linearly precoded OFDMA, LP-OFDMA) in the uplink: Variable bit rate by assigning different sub-channels to different users based on the channel conditions
o Turbo principle error-correcting codes: To minimize the required SNR at the reception side
* Channel-dependent scheduling: To utilize the time-varying channel.
* Link adaption: Adaptive modulation and error-correcting codes
* Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol

4G features

According to the members of the 4G working group, the infrastructure and the terminals of 4G will have almost all the standards from 2G to 4G implemented. Although legacy systems are in place to adopt existing users, the infrastructure for 4G will be only packet-based (all-IP). Some proposals suggest having an open Internet platform. Technologies considered to be early 4G include: Flash-OFDM, the 802.16e mobile version of WiMax (also known as WiBro in South Korea), and HC-SDMA (see iBurst).

Components

Access schemes

As the wireless standards evolved, the access techniques used also exhibited increase in efficiency, capacity and scalability. The first generation wireless standards used plain TDMA and FDMA. In the wireless channels, TDMA proved to be less efficient in handling the high data rate channels as it requires large guard periods to alleviate the multipath impact. Similarly, FDMA consumed more bandwidth for guard to avoid inter carrier interference. So in second generation systems, one set of standard used the combination of FDMA and TDMA and the other set introduced an access scheme called CDMA. Usage of CDMA increased the system capacity, but as a drawback placed a soft limit on it rather than the hard limit (i.e. a CDMA network will not reject new clients when it approaches its limits, resulting in a denial of service to all clients when the network overloads). Data rate is also increased as this access scheme (providing the network is not reaching its capacity) is efficient enough to handle the multipath channel. This enabled the third generation systems, such as IS-2000, UMTS, HSXPA, 1xEV-DO, TD-CDMA and TD-SCDMA, to use CDMA as the access scheme. However, the issue with CDMA is that it suffers from poor spectral flexibility and computationally intensive time-domain equalization (high number of multiplications per second) for wideband channels.

Recently, new access schemes like Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Interleaved FDMA and Multi-carrier CDMA (MC-CDMA) are gaining more importance for the next generation systems. These are based on efficient FFT algorithm and frequency domain equalization, resulting lower number of multiplications per second. They also make it possible to control the bandwidth and form the spectrum in a flexible way. However, they require advanced dynamic channel allocation and traffic adaptive schedululing.

WiMax is using OFDMA in the downlink and in the uplink. For the next generation UMTS, OFDMA is used for the downlink. By contrast, IFDMA is being considered for the uplink since OFDMA contributes more to the PAPR related issues and results in nonlinear operation of amplifiers. IFDMA provides less power fluctuation and thus avoids amplifier issues. Similarly, MC-CDMA is in the proposal for the IEEE 802.20 standard. These access schemes offer the same efficiencies as older technologies like CDMA. Apart from this, scalability and higher data rates can be achieved.

The other important advantage of the above mentioned access techniques is that they require less complexity for equalization at the receiver. This is an added advantage especially in the MIMO environments since the spatial multiplexing transmission of MIMO systems inherently requires high complexity equalization at the receiver.

In addition to improvements in these multiplexing systems, improved modulation techniques are being used. Whereas earlier standards largely used Phase-shift keying, more efficient systems such as 64QAM are being proposed for use with the 3GPP Long Term Evolution standards.

IPv6 support

Unlike 3G, which is based on two parallel infrastructures consisting of circuit switched and packet switched network nodes respectively, 4G will be based on packet switching only. This will require low-latency data transmission.

By the time that 4G is deployed, the process of IPv4 address exhaustion is expected to be in its final stages. Therefore, in the context of 4G, IPv6 support is essential in order to support a large number of wireless-enabled devices. By increasing the number of IP addresses, IPv6 removes the need for Network Address Translation (NAT), a method of sharing a limited number of addresses among a larger group of devices, although NAT will still be required to communicate with devices that are on existing IPv4 networks.

As of June 2009, Verizon has posted specifications that require any 4G devices on its network to support IPv6.

Advanced Antenna Systems

The performance of radio communications depends on an antenna system, refer to smart or intelligent antenna. Recently, multiple antenna technologies are emerging to achieve the goal of 4G systems such as high rate, high reliability, and long range communications. In the early 90s, to cater the growing data rate needs of data communication, many transmission schemes were proposed. One technology, spatial multiplexing, gained importance for its bandwidth conservation and power efficiency. Spatial multiplexing involves deploying multiple antennas at the transmitter and at the receiver. Independent streams can then be transmitted simultaneously from all the antennas. This increases the data rate into multiple folds with the number equal to minimum of the number of transmit and receive antennas. This is called MIMO (as a branch of intelligent antenna). Apart from this, the reliability in transmitting high speed data in the fading channel can be improved by using more antennas at the transmitter or at the receiver. This is called transmit or receive diversity. Both transmit/receive diversity and transmit spatial multiplexing are categorized into the space-time coding techniques, which does not necessarily require the channel knowledge at the transmit. The other category is closed-loop multiple antenna technologies which use the channel knowledge at the transmitter..

Software-Defined Radio (SDR)

SDR is one form of open wireless architecture (OWA). Since 4G is a collection of wireless standards, the final form of a 4G device will constitute various standards. This can be efficiently realized using SDR technology, which is categorized to the area of the radio convergence

History of 4G and pre-4G technologies

In 2002, the strategic vision for 4G — which ITU designated as IMT-Advanced — was laid out.
In 2005, OFDMA transmission technology is chosen as candidate for the HSOPA downlink, later renamed 3GPP Long Term Evolution (LTE) air interface E-UTRA.
In mid-2006, Sprint Nextel announced that it would invest about US$ 5 billion in a WiMAX technology buildout over the next few years[14] ($5.29 billion in real terms[15]). Since that time Sprint has faced many setbacks, that have resulted in steep quarterly losses. On May 7, 2008, Sprint, Imagine, Google, Intel, Comcast, Bright House, and Time Warner announced a pooling of an average of 120 MHz of spectrum; Sprint merged its Xohm WiMAX division with Clearwire to form a company which will take the name Clear.
In February 2007, the Japanese company NTT DoCoMo tested a 4G communication system prototype with 4x4 MIMO called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo completed a trial in which they reached a maximum packet transmission rate of approximately 5 Gbit/s in the downlink with 12x12 MIMO using a 100 MHz frequency bandwidth while moving at 10 km/h,[16] and is planning on releasing the first commercial network in 2010.
In September 2007, NTT Docomo demonstrated e-UTRA data rates of 200 Mbit/s with power consumption below 100 mW during the test.
In January 2008, a U.S. FCC spectrum auction for the 700 MHz former analog TV frequencies began. As a result, the biggest share of the spectrum went to Verizon Wireless and the next biggest to AT&T.Both of these companies have stated their intention of supporting LTE.
In January 2008, EU commissioner Viviane Reding suggested re-allocation of 500–800 MHz spectrum for wireless communication, including WiMAX.
February 15, 2008 - Skyworks Solutions released a front-end module for e-UTRAN.
In April 2008, LG and Nortel demonstrated e-UTRA data rates of 50 Mbit/s while travelling at 110 km/h.
In 2008, ITU-R established the detailed performance requirements of IMT-Advanced, by issuing a Circular Letter calling for candidate Radio Access Technologies (RATs) for IMT-Advanced.
April 2008, just after receiving the circular letter, the 3GPP organized a workshop on IMT-Advanced where it was decided that LTE-Advanced, an evolution of current LTE standard, will meet or even exceed IMT-Advanced requirements following the ITU-R agenda.
In December 2009, Sprint began advertising 4G service in selected cities in the United States, despite maximum download speeds of only 10Mbit/s
On December 14, 2009, the first commercial LTE deployment was in the Scandinavian capitals Stockholm and Oslo by the Swedish-Finnish network operator TeliaSonera and its Norweigan brandname NetCom (Norway). TeliaSonera branded the network "4G". The modem devices on offer were manufactured by Samsung (dongle GT-B3710), and the network infrastructure created by Huawei (in Oslo) and Ericsson (in Stockholm). TeliaSonera plans to roll out nationwide LTE across Sweden, Norway and Finland. TeliaSonera used spectral bandwidth of 10 MHz, and single-in-single-out, which should provide physical layer net bitrates of up to 50 Mbit/s downlink and 25 Mbit/s in the uplink. Introductory tests showed a TCP goodput of 42.8 Mbit/s downlink and 5.3 Mbit/s uplink in Stockholm.

Deployment plans

In May 2005, Digiweb, an Irish fixed and wireless broadband company, announced that they have received a mobile communications license from the Irish Telecoms regulator, ComReg. This service will be issued the mobile code 088 in Ireland and will be used for the provision of 4G Mobile communications.Digiweb launched a mobile broadband network using FLASH-OFDM technology at 872 MHz.

On September 20, 2007, Verizon Wireless announced that it plans a joint effort with the Vodafone Group to transition its networks to the 4G standard LTE. On December 9, 2008, Verizon Wireless announced that they intend to build and begin to roll out an LTE network by the end of 2009.

Telus and Bell Canada, the major Canadian cdmaOne and EV-DO carriers, have announced that they will be cooperating towards building a fourth generation (4G) LTE wireless broadband network in Canada. As a transitional measure, they are implementing 3G UMTS to go live by early 2010.

Sprint offers a 3G/4G connection plan, currently available in select cities in the United States.It delivers rates up to 36 Mbit/s.

O2 is to use Slough as a guinea pig in testing the 4G network and has called upon Huawei to install LTE technology in six masts across the town to allow people to talk to each other via HD video conferencing and play PlayStation games while on the move.

Current research

Pervasive networks are an amorphous and at present entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See vertical handoff, IEEE 802.21). These access technologies can be Wi-Fi, UMTS, EDGE, or any other future access technology. Included in this concept is also smart-radio (also known as cognitive radio technology) to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.

4G wireless standards

In September 2009 the technology proposals have been submitted to ITU-R as 4G candidates[34]. Basically all proposals are based on two technologies:

LTE Advanced standardized by the 3GPP;

802.16m standardized by the IEEE.

Considering the huge industry support for 3GPP based technologies such as LTE the vision of an almost unified global 4G standard might not be out of reach anymore. A first set of 3GPP requirements on LTE Advanced has been approved in June 2008[35]. LTE Advanced will be standardized in 2010 as part of the Release 10 of the 3GPP specification. LTE Advanced will be fully built on the existing LTE specification Release 10 and not be defined as a new specification series. A summary of the technologies that have been studied as the basis for LTE Advanced is summarized in a technical report

PC Modem Troubleshooting

2010-01-09T05:49:00.000-08:00

How to troubleshoot a Windows PC Modem.

* Check the telephone cable connectors and cable. It should be 10 feet or less and contain a correct RJ11 cable connector.

* Check to ensure that you are plugged into the correct modem jack. An RJ45 will not fit into an RJ11 but an RJ11 (6 pin) will fit into an RJ45 (8 pin) receptacle. It will be a loose fit. the RJ45 is for your network interface card. RJ11 is your modem (telephone).

* Check to ensure that the wall phone jack is functioning. Plug a phone into the same wall jack and ensure that you get a dial tone on your phone.

* Check for error messages => wrong username or password then contact your ISP for the correct account settings. Check to ensure that your ISP did not disconnect you for violations or failure to pay your bill.

* Check error messages in Event Viewer. Start / Settings / Control Panel / Administrative Tools / Computer Management (or Event Viewer)

* Digital Lines - NEVER plug your modem into a digital line without a CORRECT filter. This will fry your modem.

* Mobile Services - PDA (Personal Digital Assistant) Palm Pilots use COM9 - watch for conflicts.

* Connect to a different test server to determine if you having problems with your ISP.

* Reset the BIOS (Re-boot and tap the F2 Key, Press F9 (Default Settings), Press F10 (Save and Exit)

* Uninstall and replace the drivers using Device Manager under Administrator Privileges - right click on My Computer / Properties / Hardware / Device Manager - expand Modem line item. Right click on the items below and select uninstall drive on the pop-up menu. Re-boot the system and Plug and Play will automatically detect the Modem device and re-install the drivers for you.

* Reseat the modem.

* For Notebooks - perform a hard reset.

* Disable "Wait for Dial Tone". If you have Voice Mail then this will cause the modem to be unable to detect a dial tone.

* Reduce your port speed on your modem settings.

* Use Hyperterminal or another tool to test the modem.

* Perform Modem Diagnostics test.

* Check the initialization strings.

* Perform an MSCONFIG if your computer has it.

* Shut down all other applications to avoid conflicts. Remove all other hardware devices.

* Turn the date back to the January 1, 2000 or an earlier date. There are known Y2K issues and driver bomb errors related to dates. If this solves the problem then get a new driver from the modem manufacturer or your oem manufacturer.

* Perform a recovery. Ensure that you backup your data prior to doing a recovery.

* If the problem persists then send in for service.

Troubleshooting (Modem is busy)

2010-01-07T06:05:00.000-08:00

What this means depends on what program sent it. The modem could actually be in use (busy). Another cause reported for the SuSE distribution is that there may be two serial drivers present instead of one. One driver was built into the kernel and the second was a module.

In kppp, this message is sent when an attempt to get/set the serial port "stty" parameters fails. (It's similar to the "Input/output error" one may get when trying to use "stty -F /dev/ttySx"). To get a few of these stty parameters, the true address of the port must be known to the driver. So the driver may have the wrong address. The setserial" command will display what the driver thinks but it's likely wrong in this case. So what the "modem busy" often means is that the serial port (and thus the modem) can't be found.

If you have a pci modem, then use one of these commands: lspci -v, or cat /proc/pci, or dmesg to find the correct address and irq of the modem's serial port. Then check to see if "setserial" shows the same thing. If not, you need to run a script at boot-time which contains a setserial command that will tell the driver the correct address and irq.

Troubleshooting(My Modem is Physically There but Can't be Found )

2010-01-07T06:03:00.000-08:00

The error message might also be something like "Modem not responding". There are at least 4 possible reasons:

1. Your modem is a winmodem and no working driver has been installed for it. Or the modem is defective or in "online data mode" where it doesn't respond. See winmodem_
2. Your modem is disabled since both the BIOS and Linux failed to enable it. It has no IO address.
3. Your modem is enabled and has an IO address but it has no ttyS device number (like ttyS14) assigned to that address so the modem can't be used.
4. You modem does have a ttyS number assigned to it (like ttyS4) but you are using the wrong ttyS number (like ttyS2 instead of ttyS4). See wrong_ttySx and/or wvdial and/or minicom (test modem)

Case 1: Winmodem

For a winmodem with no driver (or a defective modem) the serial port that the modem is on can usually be found OK. But when the wvdial program (or whatever) interrogates that port, it gets no response since winmodems need a driver to do anything. So you see a message saying that no modem was found. However, it's likely that the modem card was detected at boot-time and it displays a message implying that a modem was found. So you're told both that the modem was found and that it wasn't found! What it all means is that no working modem has been found, since a modem that doesn't work has been found. Of course it could not be working for reasons other than being a winmodem (or linmodem) with no driver. See Software-based Modems (winmodems, linmodems).
Cases 2-3

Cases 2. and 3. mean that no serial port device (such as /dev/ttyS2) exists for the modem. If you suspect this, see Serial Port Can't be Found.
Case 4: Wrong ttySx number

If you are lucky, the problem is case 4. Then you just need to find which ttyS your modem is on.
wvdial

There's a program that looks for modems on commonly used serial ports called "wvdialconf". Just type "wvdialconf ". It will create the new file as a configuration file but you don't need this file unless you are going to use "wvdial" for dialing. See What is wvdialconf ? Unfortunately, if your modem is in "online data" mode, wvdialconf will report "No modem detected". See minicom (test modem)
minicom (test modem)

Another way try to find out if there's a modem on a certain port is to start "minicom" on the port (after first setting up minicom for that serial port. You will need to save the setup and then exit minicom and start it again. Then type "AT" and you should see "OK". If you don't, try typing ATQ0 V1 EI. If you still don't get OK (and likely don't even see the AT you typed) then there is likely no modem on the port. This may be due to either case 1. 2. or 3. above

If what you type is really getting thru to a modem, then the lack of response could be due to the modem being in "online data" mode where it can't accept any AT commands. You may have been using the modem and then abruptly disconnected (such as killing the process with signal 9). In that case your modem did not get reset to "command mode" where it can interact to AT commands. "Minicom" may display "You are already online. Hangup first." (For another meaning of this minicom message see You are already online! Hang up first.) Well, you are sort of online but you are may not be connected to anything over the phone line. Wvdial will report "modem not responding" for the same situation.

To fix this as a last resort you could reboot the computer. Another way to try to fix this is to send +++ to the modem to tell it to escape back to "command mode" from "online data mode". On both sides of the +++ sequence there must be about 1 second of delay (nothing sent during "guard time"). This may not work if another process is using the modem since the +++ sequence could wind up with other characters inserted in between them or after the +++ (during the guard time). Ironically, even if the modem line is idle, typing an unexpected +++ is likely to set off an exchange of control packets (that you never see) that will violate the required guard time so that the +++ doesn't do what you wanted. +++ is usually in the string that is named "hangup string" so if you command minicom (or the like) to hangup it might work. Another way to do this is to just exit minicom and then run minicom again.

Other problems which you might observe in minicom besides no response to AT are:

It takes many seconds to get an expected truncated response (including only the cursor moving down one line). See Extremely Slow: Text appears on the screen slowly after long delays
Some strange characters appear but they are not in response to AT. This likely means that your modem is still connected to something at the other end of the phone line which is sending some cryptic packets or the like.

What Speed Should I Use with My Modem?

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By "speed" we really mean the "data flow rate" but almost everybody incorrectly calls it speed. For all modern modems you have no choice of the speed that the modem uses on the telephone line since it will automatically choose the highest possible speed that is feasible under the circumstances. If one modem is slower than the other, then the faster modem will operate at the slower modem's speed. On a noisy line, the speed will drop still lower.

While the above speeds are selected automatically by the modems you do have a choice as to what speed will be used between your modem and your computer (PC-to-modem speed). This is sometimes called "DTE speed" where "DTE" stands for Data Terminal Equipment (Your computer is a DTE.) You need to set this speed high enough so this part of the signal path will not be a bottleneck. The setting for the DTE speed is the maximum speed of this link. Most of the time it will likely actually operate at lower speeds.

For an external modem, DTE speed is the speed (in bits/sec) of the flow over the cable between you modem and PC. For an internal modem, it's the same idea since the modem also emulates a serial port. It may seem ridiculous having a speed limit on communication between a computer and a modem card that is directly connected inside the computer to a much higher speed bus. But it's usually that way since the modem card probably includes a dedicated serial port which does have speed limits (and settable speeds). However, some software modems have no such speed limits.

Speed and Data Compression

What speed do you choose? If it were not for "data compression" one might try to choose a DTE speed exactly the same as the modem speed. Data compression takes the bytes sent to the modem from your computer and encodes them into a fewer number of bytes. For example, if the flow (speed) from the PC to the modem was 20,000 bytes/sec (bps) and the compression ratio was 2 to 1, then only 10,000 bytes/sec would flow over the telephone line. Thus for a 2:1 compression ratio you would need to set the DTE speed to double the maximum modem speed on the phone line. If the compression ratio were 3 to 1 you would need to set it 3 times faster, etc.

Where do I Set Speed ?

This DTE (PC-to-modem) speed is normally set by a menu in your communications program or by an option given to the getty command if someone is dialing in. You can't set the DCE modem-to-modem speed since this is set automatically by the modem to the highest feasible speed after negotiation with the other modem. Well, actually you can set the modem-to-modem speed with the S37 register but you shouldn't do it. If the two modems on a connection were to be set this way to different speeds, then they couldn't communicate with each other.

Can't Set a High Enough Speed

Speeds over 115.2kbps

The top speed of 115.2k has been standard since the mid 1990's. But by the year 2000, most new serial ports supported higher speeds of 230.4k and 460.8k. Some also support 921.6k. Unfortunately Linux seldom uses these speeds due to lack of drivers. Thus such ports behave just like 115.2k ports unless the higher speeds are enabled by special software. To get these speeds you need to compile the kernel with special patches or use modules until support is built into the kernel's serial driver.

Unfortunately serial port manufacturers never got together on a standard way to support high speeds, so the serial driver needs to support a variety of hardware. Once high speed is enabled, a standard way to choose it is to set baud_base to the highest speed with setserial (unless the serial driver does this for you). The software will then use a divisor of 1 to set the highest speed. All this will hopefully be supported by the Linux kernel sometime in 2003.

A driver for the w83627hf chip (used on many motherboards such as the Tyan S2460) is at https://www.muru.com/linux/w83627hf/

A non-standard way that some manufacturers have implemented high speed is to use a very large number for the divisor to get the high speed. This number isn't really a divisor at all since it doesn't divide anything. It's just serves as a code number to tell the hardware what speed to use. In such cases you need to compile the kernel with special patches.

One patch to support this second type of high-speed hardware is called shsmod (Super High Speed Mode). There are both Windows and Linux versions of this patch. See http://www.devdrv.com/shsmod/. There is also a module for the VIA VT82C686 chip http://www.kati.fi/viahss/. Using it may result in buffer overflow.

For internal modems, only a minority of them advertise that they support speeds of over 115.2k for their built-in serial ports. Does shsmod support these ??
How speed is set in hardware: the divisor and baud_base

Speed is set by having the serial port's clock change frequency. But this change happens not by actually changing the frequency of the oscillator driving the clock but by "dividing" the clock's frequency. For example, to divide by two, just ignore every other clock tick. This cuts the speed in half. Dividing by 3 makes the clock run at 1/3 frequency, etc. So to slow the clock down (meaning set speed), we just send the clock a divisor. It's sent by the serial driver to a register in the port. Thus speed is set by a divisor.

If the clock runs at a top speed of 115,000 bps (common), then here are the divisors for various speeds (assuming a maximum speed of 115,200): 1 (115.2k), 2 (57.6k), 3 (38.4k), 6 (19.2k), 12 (9.6k), 24 (4.8k), 48 (2.4k), 96 (1.2k), etc. The serial driver sets the speed in the hardware by sending the hardware only a "divisor" (a positive integer). This "divisor" divides the "maximum speed" of the hardware resulting in a slower speed (except a divisor of 1 obviously tells the hardware to run at maximum speed).

There are exceptions to the above since for certain serial port hardware, speeds above 115.2k are set by using a very high divisor. Keep that exception in mind as you read the rest of this section. Normally, if you specify a speed of 115.2k (in your communication program or by stty) then the serial driver sets the port hardware to divisor 1 which sets the highest speed.

Besides using a very high divisor to set high speed, the conventional way to do it is as follows: If you happen to have hardware with a maximum speed of say 230.4k (and the 230.4k speed has been enabled in the hardware), then specifying 115.2k will result in divisor 1. For some hardware this will actually give you 230.4k. This is double the speed that you set. In fact, for any speed you set, the actual speed will be double. If you had hardware that could run at 460.8k then the actual speed would be quadruple what you set. All the above assumes that you don't use "setserial" to modify things.
Setting the divisor, speed accounting

To correct this accounting (but not always fix the problem) you may use "setserial" to change the baud_base to the actual maximal speed of your port such as 230.4k. Then if you set the speed (by your application or by stty) to 230.4k, a divisor of 1 will be used and you'll get the same speed as you set.

If you have very old software which will not allow you to tell it such a high speed (but your hardware has it enabled) then you might want to look into using the "spd_cust" parameter. This allows you to tell the application that the speed is 38,400 but the actual speed for this case is determined by the value of "divisor" which has also been set in setserial. I think it best to try to avoid using this kludge.

There are some brands of UARTs that uses a very high divisor to set high speeds. There isn't any satisfactory way to use "setserial" (say set "divisor 32770") to get such a speed since then setserial would then think that the speed is very low and disable the FIFO in the UART.
Crystal frequency is higher than baud_base

Note that the baud_base setting is usually much lower than the frequency of the crystal oscillator since the crystal frequency of say 1.8432 MHz is divided by 16 in the hardware to get the actual top speed of 115.2k. The reason the crystal frequency needs to be higher is so that this high crystal speed can generate clock ticks to take a number of samples of each bit to determine if it's a 1 or a 0.

Actually, the 1.8432 MHz "crystal frequency" may be obtained from a 18.432 MHz crystal oscillator by dividing by 10 before being fed to the UART. Other schemes are also possible as long as the UART performs properly.

Speed Table

It's best to have at least a 16650 UART for a 56k modem but few modems or serial ports provide it. Second best is a 16550 that has been tweaked to give 230,400 bps (230.4 kbps). Most people still use a 16550 that is only 115.2 kbps but it's claimed to only slow down thruput by a few percent (on average). This is because a typical compression ratio is 2 to 1 and for downloading compressed files (packages) it's 1 to 1. There's no degradation for these cases. Here are some suggested speeds to set your serial line if your modem speed is:

56k (V.92): use 115.2 kbps or 230.4 kbps (best)
56k (V.90): use 115.2 kbps or 230.4 kbps (best)
33.6k (V.34bis): use 115.2 kbps
28.8k (V.34): use 115.2 kbps
14.4k (V.32bis): use 57600 bps
9.6k (V.32): use 38400 bps
slower than a 9600 bps (V.32) modem: Set the speed to the same speed as the modem (unless you have data compression).

All the above speeds may use V.42bis data compression and V.42 error correction. If data compression is not used then the speed may be set lower so long as it's above the modem speed.

Modems for a Linux PC

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Many Winmodems Will Not Work with Linux

Unfortunately, some software modems (winmodems) will not work with Linux due to lack of Linux drivers. Configuring the software modems that can be made to work with Linux ranges from very easy (automatically) to difficult, depending on both the modem, your skills, and how easy it is to find info about your modem --info that is not all in this HOWTO. If you buy a new one that you're not sure will work under Linux, try to get an agreement that you can return it for a refund if it doesn't work out.

Even if your modem works with Linux it can't be used until the serial port it's located on is enabled and made known to the operating system. For a detailed explanation of this (or if boot-time messages don't show your modem's serial port) study this HOWTO or see Plug-and-Play-HOWTO.

External vs. Internal

A modem for a PC may be either internal, external serial, or external USB. The internal one is installed inside of your PC (you must remove screws, etc. to install it). An external one just plugs in to a cable: USB cable (USB modem) or to the serial port (RS-232 serial modem). As compared to external serial modems, the internal modems are less expensive, are less likely to to suffer data loss due to buffer overrun, and usually use less electricity. An internal modem obviously doesn't use up any desk space.

External serial modems are usually easier to install and usually has less configuration problems provided the serial port you'll connect it to is configured OK. External USB modems are more likely to be winmodems and are reportedly usually more difficult to deal with than external serial modems. External modems have lights which may give you a clue as to what is happening and aid in troubleshooting. The fact that the serial port and modem can be physically separated also aids in troubleshooting. External modems are easy to move to another computer. If you need to turn the power off to reset your modem (this is seldom necessary) then with an external you don't have to power down the entire PC.

Unfortunately, most external serial modems have no switch to turn off the power supply when not in use and thus are likely to consume a little electricity even when turned off (unless you unplug the power supply from the wall). Each watt they draw usually costs you over $1/yr. Another possible disadvantage of an external is that you will be forced to use an existing serial port which may not support a speed of over 115,200 bps (although as of late 2000 most new internal modems don't either --but some do). For details Can't Set a High Enough Speed

Is a Driver Needed ?

Any modem, of course, needs the serial driver that comes with Linux (either built into the kernel or as a module). For PCI, this driver should also detect the modem but it's not really a modem driver since it just detects which serial port the modem is on.

But what about modem drivers? Any software modem (winmodem, linmodem) must have a modem driver (if it exists for Linux). Hardware modems don't really need any modem driver unless you want to use special features such as voice and "modem on hold".

Software modems require software to run them and obviously do need a driver. The drivers for MS Windows are *.exe programs which will not run under Linux. So you must use a Linux driver (if it exists). See Software-based Modems

External Modems

Do they all work under Linux?

At one time (2002 ?) all external modems would work under Linux. But then came the controllerless external modem which wouldn't. If the box says it requires Windows with no mention of Linux it could mean just that. Could it be that Windows software is provided for "modem on hold" and for use as an answering machine, etc., but that otherwise it will work under Linux? Linux may not support these features very well if at all. If this is a recent version of Modem-HOWTO, let me know of your experience with this.
PnP External Modems

Many external modems are labeled "Plug and Play" (PnP). If they are hardware modems, they should all work as non-PnP modems. While the serial port itself may need to be configured (IRQ number and IO address) unless the default configuration is OK, an external modem uses no such IRQ/IO configuration. You just plug the modem into the serial port.

The PnP modem has a special PnP identification built into it that can be read (thru the serial port) by a PnP operating system. Such an operating system would then know that you have a modem on a certain port and would also know the id number. If it's a controllerless modem, it could try to locate a driver for it. It could also tell application programs what port your modem is on (such as /dev/ttyS2 or COM3). But Linux may not be able to do this. Thus you may need to configure your application program manually by giving it the ttyS number (such as /dev/ttyS2). Some programs like wvdial can probe for a modem on various ports.
Cabling & Installation

Connecting an external modem is simple compared to connecting most other devices to a serial port that require various types of "null modem" cables (which will not work for modems). Modems use a straight through cable, with no pins crossed over. Most computer stores should have one. Make sure you get the correct gender and number of pins. Hook up your modem to one of your serial ports. If you are willing to accept the default IRQ and IO address of the port you connect it to, then you are ready to start your communication program and configure the modem itself.
What the Lights (LED's) Mean (for some external modems)

TM Test Modem
AA Auto Answer (If on, your modem will answer an incoming call)
RD Receive Data line = RxD
SD Send Data line = TxD
TR data Terminal Ready = DTR (set by your PC)
RI Ring Indicator (If on, someone is "ringing" your modem)
OH Off Hook (If off, your modem has hung up the phone line)
MR Modem Ready = DSR ??
EC Error Correction
DC Data Compression
HS High Speed (for this modem)

Internal Modems

An internal modem is installed in a PC by taking off the cover of the PC and inserting the modem card into a vacant slot on the motherboard. There are modems for PCI slots, other modems for the older ISA slots, and ARM software "modems" for the new small AMR slot. Only some newer PCs will have ARM slots. While external modems plug into the serial port (via a short cable) the internal modems have the serial port built into the modem. In other words, the modem card is both a serial port and a modem.

Setting the IO address and IRQ for a serial port was formerly done by jumpers on the card. These are little black rectangular "cubes" about 5x4x2 mm in size which push in over pins on the card. Plug-and-Play modems (actually the serial port part of the modems) don't use jumpers for setting these but instead are configured by sending configuration commands to them over the bus inside the computer. Such configuration commands can be sent by a PnP BIOS, by the isapnp program (for the ISA bus only), by setpci (PCI bus: can't set IRQs), or by newer serial of how to configure the ones that don't get io-irq configured by the serial driver.

1. ISA bus: Use "isapnp" which may be run automatically at every boot-time
2. Let a PnP BIOS do it, and then maybe tell setserial the IO and IRQ
3. PCI bus: Use lspci -vv to look at it and setpci to configure the IO only (can't set the IRQ).
See Quick Install for more details, especially for the PCI bus.

Software-based Modems (winmodems, linmodems)

Introduction to software modems (winmodems)

Software modems turn over some (or even almost all) of the work of the modem to the main processor (CPU) chip of your computer (such as a Pentium chip). This requires special software (a modem driver) to do the job. Until late 1999, such software was released only for MS Windows and wouldn't work with Linux. Even worse was that the maker of the modem kept the interface to the modem secret so that no one could write a Linux driver for it (even though a few volunteers were willing to write Linux drivers).

But things have improved some since then so that today (late 2001) many such modems do have a linux driver. There is no standard interface so that different brands/models of software-modems need different drivers (unless the different brands/models happen to use the same chipset internally). But some drivers may not work perfectly nor have all the features that a MS Windows driver has.

Another name for a software modem (used by MS) is "driver-based modem". The conventional hardware-based modem (that works with Linux) doesn't need a modem driver (but does use the Linux serial driver) After about mid-1998 most new internal modems were software modems.

Software modems fall into 2 categories: linmodems and winmodems. Winmodems will only work under MS Windows. Linmodems will work under Linux. They formerly were mostly winmodems so some also call them "winmodems". The term "Winmodem" is also a trademark for a certain model of "winmodem" but that's not the meaning of it in this document.
Linmodems

In late 1999, two software-based modems appeared that could work under Linux and were thus called "linmodems". Lucent Technologies (LT) unofficially released a Linux binary-only code to support most of its PCI modems. PC-TEL (includes "Zoltrix") introduced a new software-based modem for Linux. After that, interest increased for getting winmodems to work under linux. There is a GPL'ed driver for Intel's (Modem Silicon Operations) MD563x HaM chipset (nee Ambient division of Cirrus Logic). As of mid-2001 there are also drivers for: Conexant HSF and HCF, Motorola SM56 (support terminated), ESS (ISA only), and IBM's Mwave for Thinkpads 600+. See http://linmodems.org.

What percent of software modems now (2001) work under Linux? Well, there's a number of modem chips not supported: Lucent/Agere ARM (Scorpio), 3COM/US Robotics, some SmartLink (3 different chipsets), Ambient HSP, and possibly others. So it seems that over half the software modem chips were supported as of late 2001. As of 2005 it seems that the situation has gotten worse. Why? Well, Linux on the Desktop didn't grow as fast as expected and many PC users went for higher speed cable modems and DSL.

Another reason is that many of the drivers were written years ago and will only work for older versions of the Linux kernels. The driver code is secret and the companies don't want to update drivers for hardware they are no longer selling.

Be warned in advance that determining if your modem is a linmodem may not be very easy. You may need to first find out what chipset you have and who makes it. Just knowing the brand and model number of your modem may not be sufficient. One method is to download the scanModem tool from http://linmodems.org but the results may be hard to decipher and you may need to ask for help from the linmodems mailing list. Another way to find this out using say "lspci -v" and then looking up the chip maker using the long modem number. This requires checking a database or searching the Internet. Still another way is to look at the fine print on the chips on the modem card. All this is not always simple. It could happen that you will put a lot of effort into this only to get the bad news that your modem isn't supported. But even if it is supported, support may only be for an old version of the kernel. See Linmodem-HOWTO for more details.
Linmodem sites and documentation

Linmodem-HOWTO
Winmodems-and-Linux-HOWTO (not as well written as Linmodem-HOWTO)
http://linmodems.org is a project to turn winmodems into linmodems. Has a mailing list.
Conexant+Rockwell-modem-HOWTO
old modem list Has links to linmodem info, but not maintained after 2003.
PCTel-HSP-MicroModem-Configuration-mini-HOWTO

Software-based modem types

There are two basic types of software modems. In one type the software does almost all of the work. The other is where the software only does the "control" operations (which is everything except processing the digital waveshapes --to be explained later). Since the hardware doesn't do the control it's called a "controllerless" modem. The first type is an all-software modem (sometimes just called a software modem).

For both of these types there must be analog hardware in the modem (or on the motherboard) to generate an electrical waveshape to send out the phone line. It's generated from a digital signal (which is sort of a "digital waveshape"). It's something like the digital electronics creates a lot of discrete points on graph paper and then the modem draws a smooth voltage curve thru them. There must also be hardware to convert the incoming waveshape to digital. This is just analog-to-digital conversion (and conversely). It's done by a codec (coder-decoder).

The incoming digital waveshape must be converted to a data byte stream. This is part of the demodulation process. Recall that these data bytes have likely been compressed, so they are not at all like the original message. Turning data bytes into a digital waveshape is part of the modulation process. Even after demodulation is done, the modem can't just send the resulting incoming data byte stream to the serial port input buffers, but must first do decompression, error correction, and convert from serial to the parallel bus of the computer. But the modem may get the CPU to do the actual work. It's the reverse sequence for an outgoing data byte stream.

The difference between the two types of software-based modems is where the digital modulation takes place. In the all-software modem this modulation is done in the CPU and it's called a Host Signal Processor (HSP). In the controllerless modem it's done in the modem but all other digital work is done by the CPU. This other digital work consists of dealing with AT-commands, data compression, error correction, and simulating a serial port. In the all-software modem, there are still two items handled by hardware: the A/D conversion of waveshapes by the codec and echo cancellation.
Is this modem a software modem?

How do you determine if an internal modem is a software modem? First see if the name, description of it, or even the name of the MS Windows driver for it indicates it's a software modem: HSP (Host Signal Processor) , HCF (Host Controlled Family), HSF (Host Signal Family), controllerless, host-controlled, host-based, and soft-... modem. If it's one of these modem it will only work for the cases where a Linux driver is available. Since software modems cost less, a low price is a clue that it's a software modem.

If you don't know the model of the modem and you also have Windows on your Linux PC, click on the "Modem" icon in the "Control Panel". Then see the modem list (not maintained after 2003). If the above doesn't work (or isn't feasible), you can look at the package the modem came in (or a manual). Read the section on the package that says something like "Minimum System Requirements" or just "System Requirements".

A hardware modem will work fine on old CPUs (such as the 386 or better). So if it requires a modern CPU (such as a Pentium or other "high speed" CPU of say over 150 MHz) this is a clue that it's a all-software modem. If it only requires a 486 CPU (or better) then it's likely a host-controlled software modem. Saying that it only works with Windows is also bad news. However, even in this case there may be a Linux driver for it or it could be a mistake in labeling.

Otherwise, it may be a hardware modem if it fails to state explicitly that you must have Windows. By saying it's "designed for Windows" it may only mean that it fully supports Microsoft's plug-and-play which is OK since Linux uses the same plug-and-play specs (but it's harder to configure under Linux). Being "designed for Windows" thus gives no clue as to whether or not it will work under Linux. You might check the Website of the manufacturer or inquire via email. Some manufacturers are specifically stating that certain models work under Linux. Sometimes they are linmodems that require you to obtain and install a certain linmodem driver.
Should I get a software modem?

Only if you know there is a Linux driver for it that works OK. But there may be a problem if the driver isn't being maintained and as a result doesn't work with future versions of the kernel. Also, the driver may not have full functionality. Besides the problems of getting a satisfactory driver, what are the pros and cons of software modems? Since the software modem uses the CPU to do some (or all) of its work, the software modem requires less on-board electronics on the modem card and thus costs less. At the same time, the CPU work load is increased by the modem which may result in slower operation.

The percentage of loading of the CPU by the modem depends on both what CPU you have and whether or not it's an all-software modem. For a modern CPU and a modem that only uses the CPU as a controller, there's little loss of performance. Even if it's an all-software modem, you will not suffer a loss of performance if there are no other CPU-intensive tasks are running at the same time. Of course, when you're not using the software modem there is no degradation in performance at all.

Is the modem cost savings worth it? In many cases yes, especially if you don't use the modem much and/or are not running any other CPU intensive tasks when the modem is in use. The savings in modem cost could be used for a better CPU which would speed things up a little. But the on-board electronics of a hardware modem can do the job more efficiently than a general purpose CPU (except that it's not efficient at all when it's not in use). So if you use the modem a lot it's probably better to avoid all-software modems.

PCI Modems

A PCI modem card is one which inserts into a PCI-bus slot on the motherboard of a PC. While many PCI winmodems will not work under Linux (no driver available) other PCI modems will work under Linux. The Linux serial driver has been modified to support certain PCI hardware modem cards (but not winmodems/linmodems). If it's a linmodem, it will work only if you install a certain linmodem driver. If the Linux serial driver supports your hardware modem then the driver will set up the PnP configuration for you. See PCI Bus Support Underway. If no special support for your PCI hardware modem is in the Linux serial driver it may still work OK but you have to do some work to configure it.

AMR Modems

These are mainly used in laptops. They are all winmodems that insert into a special AMR (Audio Modem Riser) slot on the motherboard. Audio cards or combined audio-modem cards are sometimes used in this slot. The slot's main use is for HSF type modems where the CPU does almost all of the work. This results in a small "modem" card and thus a short AMR slot. The motherboard has a codec which takes digital output from the CPU and generates analog voltage waves at the ARM slot (and conversely). Thus the "modem" that plugs into the slot has little to do except to interface the telephone line with the codec. Linux supports at least one AMR modem. lspci -v should display it.

USB Modems

USB = Universal Serial Bus. Most USB modems are winmodems, so many will not work with Linux. Linux has support for modems that conform to the USB Communication Device Class Abstract Control Model (= USB CDC ACM). There's a module for ACM named acm.o. See the /usb/acm.txt document in the kernel documentation directory (/usr/share/doc/kernel-doc-2.6.x in Debian, perhaps /usr/doc/kernel... in some distributions). The ACM "serial port" for the first (0th) such modem is: /dev/usb/acm/0 or possibly /dev/usb/ttyACM0. This should be the case regardless of whether or not you use the new "device file system". It's not really a serial port, but the driver makes it look like a serial port to software which uses the modem.

Since the bandwidth on the USB is high it's possible to send a lot more that just data to a USB modem. This means that it's feasible to create a USB winmodem where the driver does most of the modem's work on the CPU and sends the results to the modem. So beware of USB winmodems (unless they have Linux support).

Which Internal Modems might not work with Linux

Software-based Modems (winmodems, linmodems) Only about half have a Linux driver available.
MWave and DSP Modems might work, but only if you first start Windows/Dos each time you power on your PC.
Modems with Old Rockwell (RPI) Drivers work but with reduced performance.

MWave and some DSP Modems

Note that there's now a Linux driver for the ACP (Mwave) modem used in IBM Thinkpads 600+. See the mini-HOWTO: ACP-Modem.

While hardware modems used use DSPs (Digital Signal Processors) some of these DSPs are programmed by a driver which must be downloaded from the hard disk to the DSPs memory just before using the modem. Unfortunately, such downloading is normally done by Dos/Windows programs (which doesn't work for Linux). But there has been substantial success in getting some of these modems to work with Linux. For example, there is a Linux driver available to run a Lucent (DSP) modem.

Ordinary modems that work fine with Linux (without needing a driver for the modem) often have a DSP too (and may mention this on the packaging), but the program that runs the DSP is stored inside the modem. These work fine under Linux. An example of a DSP modem that has problems working under Linux is the old IBM's Aptiva MWAVE.

One way to get some DSP modems to work with Linux is to boot from DOS (if you have it on your Linux PC). You first install the driver under DOS (using DOS and not Window drivers). Then start Dos/Windows and start the driver for the modem so as to program the DSP. Then without turning off the computer, start Linux.

One may write a "batch" file (actually a script) to do this. Here is an example but you must modify it to suit your situation.

rem mwave is a batch file supplied by the modem maker
call c:\mww\dll\mwave start
rem loadlin.exe is a DOS program that will boot Linux from DOS (See
rem Config-HOWTO).
c:\linux\loadlin f:\vmlinuz root=/dev/hda3 ro

One may create an icon for the Window's desktop which points to such a batch file and set the icon properties to "Run in MSDOS Mode". Then by clicking on this icon one sets up the modem and goes to Linux. Another possible way to boot Linux from DOS is to press CTRL-ALT-DEL and tell it to reboot (assuming that you have set things up so that you can boot directly into Linux). The modem remains on the same com port (same IO address) that it used under DOS.

The Newcom ifx modem needs a small kernel patch to work correctly since its simulation of a serial port is non-standard. The patch and other info for using this modem with Linux is at http://quinine.pharmacy.ohio-state.edu/~ejolson/linux/newcom.html.
Old Rockwell (RPI) Drivers

Some older Rockwell chips need Rockwell RPI (Rockwell Protocol Interface) drivers for compression and error correction. They can still be used with Linux even though the driver software works only under MS Windows. This is because the MS Windows software (which you don't have) does only compression and error correction. If you are willing to operate the modem without compression and error correction then it's feasible to use it with Linux. To do this you will need to disable RPI by sending the modem (via the initialization string) a "RPI disable" command each time you power on your modem. On my old modem this command was +H0. Not having data compression available makes it slower to get webpages but is just as fast when downloading files that are already compressed.

3G

2009-12-17T21:00:00.000-08:00

International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd Generation, is a family of standards for mobile telecommunication defined by the International Telecommunication Union,which includes GSM EDGE, UMTS, and CDMA 2000 as well as DECTWiMax. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2,5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the uplink with HSPA+). Thus, 3G networks enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral effeciency. and

ITU defined the third generation (3G) of mobile telephony standards – IMT-2000 – to facilitate growth, increase bandwidth, and support more diverse applications. For example, GSM (the current most popular cellular phone standard) could deliver not only voice, but also circuit-switched data at download rates up to 14.4 kbps. But to support mobile multimedia applications, 3G had to deliver packet-switched data with better spectral efficiency, at far greater bandwidths

History

The first pre-commercial 3G network was launched by NTT DoCoMo in Japan branded FOMA, in May 2001 on a pre-release of W-CDMA technology.The first commercial launch of 3G was also by NTT DoCoMo in Japan on 1 October 2001, although it was initially somewhat limited in scope,broader availability was delayed by apparent concerns over reliability.The second network to go commercially live was by SK Telecom in South Korea on the 1xEV-DO technology in January 2002. By May 2002 the second South Korean 3G network was by KT on EV-DO and thus the Koreans were the first to see competition among 3G operators.

The first European pre-commercial network was at the Isle of Man by Manx Telecom, the operator then owned by British Telecom, and the first commercial network in Europe was opened for business by Telenor in December 2001 with no commercial handsets and thus no paying customers. These were both on the W-CDMA technology.

The first commercial United States 3G network was by Monet Mobile Telecom, on CDMA 2000 1x EV-DO technology, but this network provider later shut down operations. The second 3G network operator in the USA was Verizon Wireless in October 2003 also on CDMA2000 1x EV-DO. AT&T Mobility is also a true 3G network, having completed its upgrade of the 3G network to HSUPA.

The first pre-commercial demonstration network in the southern hemisphere was built in Adelaide,South Australia by m.Net Corporation in February 2002 using UMTS on 2100 MHz. This was a demonstration network for the 2002 IT World Congress. The first commercial 3G network was launched by Hutchison Telecommunications branded as Three in March 2003.

In December 2007, 190 3G networks were operating in 40 countries and 154 HDSPA networks were operating in 71 countries, according to the Global Mobile Suppliers Association (GSA). In Asia, Europe, Canada and the USA, telecommunication companies use W-CDMA technology with the support of around 100 terminal designs to operate 3G mobile networks.

In Europe, mass market commercial 3G services were introduced starting in March 2003 by 3 (Part of Hutchison) in the UK and Italy. The European Union Council suggested that the 3G operators should cover 80% of the European national populations by the end of 2005.

Roll-out of 3G networks was delayed in some countries by the enormous costs of additional spectrum licensing fees. In many countries, 3G networks do not use the same radio frequencies as 2G, so mobile operators must build entirely new networks and license entirely new frequencies; an exception is the United States where carriers operate 3G service in the same frequencies as other services. The license fees in some European countries were particulary high, bolstered by government auctions of a limited number of licenses and sealed bid auctions, and initial excitement over 3G's potential. Other delays were due to the expenses of upgrading equipment for the new systems.

By June 2007 the 200 millionth 3G subscriber had been connected. Out of 3 billion mobile phone subscriptions worldwide this is only 6.7%. In the countries where 3G was launched first - Japan and South Korea - 3G penetration is over 70%.In Europe the leading country is Italy with a third of its subscribers migrated to 3G. Other leading countries by 3G migration include UK, Austria, Australia and Singapore at the 20% migration level. A confusing statistic is counting CDMA 2000 1x RTT customers as if they were 3G customers. If using this definition, then the total 3G subscriber base would be 475 million at June 2007 and 15.8% of all subscribers worldwide.

In Canada, Rogers Wireless was the first to implement 3G technology, with HSDPA services in eastern Canada in early 2007. Their subsidiary Fido Solutions offers 3G as well. Because they were the only incumbent carrier (out of 3) with UMTS/HSDPA capability, for 2 years Rogers was the sole provider of the popular Apple iPhone. Realizing they would miss out on roaming revenue from the 2010 Winter Olympics ,Bell and Telus formed a joint venture and rolled out a shared HDSPA network using Nokia Siemens technology. Bell launched their 3G wireless lineup on 4 November 2009, and Telus followed suit a day later on 5 November 2009. With these launches, the popular iPhone is now available on all 3 incumbent national carriers

Mobitel Iraq is the first mobile 3G operator in Iraq. It was launched commercially on February 2007.

China announced in May 2008, that the telecoms sector was re-organized and three 3G networks would be allocated so that the largest mobile operator, China Mobile, would retain its GSM customer base. China Unicom would retain its GSM customer base but relinquish its CDMA2000 customer base, and launch 3G on the globally leading WCDMA (UMTS) standard. The CDMA2000 customers of China Unicom would go to China Telecom, which would then launch 3G on the CDMA 1x EV-DO standard. This meant that China would have all three main cellular technology 3G standards in commercial use. Finally in January 2009, Ministry of industry and Information Technology of China has awarded licenses of all three standards，TD-SCDMA to China Mobile, WCDMA to China Unicom and CDMA2000 to China Telecom. The launch of 3G occurred on 1 October 2009, to coincide with the 60th Anniversary of the Founding of the People's Republic of China.

In November 2008, Turkey has auctioned four IMT 2000/UMTS standard 3G licenses with 45, 40, 35 and 25 MHz top frequencies.Turkcell has won the 45 MHz band with its €358 million offer followed by Vodavone and Avea leasing the 40 and 35 MHz frequencies respectively for 20 years. The 25 MHz top frequency license remains to be auctioned.

The first African use of 3G technology was a 3G videocall made in Johannesburg on the Vodacom in Mauritius in late March 2006, a 3G service was provided by the new company Wana. network in November 2004. The first commercial launch of 3G in Africa was by EMTEL on the W-CDMA standard. In north African Morroco

T-Mobile, a major Telecommunication services provider has recently rolled out a list of over 120 U.S. cities which will be provided with 3G Network coverage in the year 2009.

In 2008, India entered into 3G Mobile arena with the launch of 3G enabled Mobile services by Mahanagar Telephone Nigam Limited (MTNL).MTNL is the first Mobile operator in India to launch 3G services.

Features

Data Rates

ITU has not provided a clear definition of the data rate users can expect from 3G equipment or providers. Thus users sold 3G service may not be able to point to a standard and say that the rates it specifies are not being met. While stating in commentary that "it is expected that IMT-2000 will provide higher transmission rates: a minimum data rate of 2 Mbit/s for stationary or walking users, and 348 kbit/s in a moving vehicle,the ITU does not actually clearly specify minimum or average rates or what modes of the interfaces qualify as 3G, so various rates are sold as 3G intended to meet customers expectations of broadband data.

Security

3G networks offer a greater degree of security than 2G predecessors. By allowing the UE (User Equipment) to authenticate the network it is attaching to, the user can be sure the network is the intended one and not an impersonator. 3G networks use the KASUMI block crypto instead of the older A5/1 stream cipher. However, a number of serious weaknesses in the KASUMI cipher have been identified

In addition to the 3G network infrastructure security, end-to-end security is offered when application frameworks such as IMS are accessed, although this is not strictly a 3G property.

Applications

3G offers a wide range of applications. These applications are mainly made possible due to the enhanced data rates as a result of the 2Mbps bandwidth availabilities. Some of the applications are.

1. Mobile TV - Due to the high data transfer rate being offered due to 3G, TV can be viewed on Mobile Phones. For this have to tie up with a service provider, through which the content can be accessed. Eg.Apalya for BSNL(India).

2. Video Conferencing - It is possible to conduct a video conferencing using the available network, due to the 2 Mbps bandwidth.

3. Tele-medicine - This is an extended feature of video conferencing where a remote person can be given attention by a doctor located at a distant place.

4. Location Based Services - These are some services which can be accessed on the dependence of the service provider. These include weather updates, live road traffic view, and vehicle tracking.

5. Video on Demand - Videos can be viewed on demand from a service provider. For providing this service, the service provider should have collaborations with content providers such as Perceptknorigin (in India). This is again possible due to high buffering speed possible due to the 3G network.

Evolution from 2G

From 2G to 2.5G

The first major step in the evolution to 3G occurred with the introduction of General Packet Radio Service . So the cellular services combined with GPRS became '2.5G.'

GPRS could provide data rates from 56 kbit/s up to 114 kbit/s. It can be used for services such as Wireless Application Protocol (WAP) access, Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access. GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is utilizing the capacity or is in an idle state.

From 2.5G to 2.75G (EDGE)

GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE was deployed on GSM networks beginning in 2003—initially by Cingular (now AT&T) in the United States.

EDGE is standardized by 3GPP as part of the GSM family, and it is an upgrade that provides a potential three-fold increase in capacity of GSM/GPRS networks. The specification achieves higher data-rates by switching to more sophisticated methods of coding (8PSK), within existing GSM timeslots.

Evolution towards 4G

Both 3GPP and 3GGP2 are currently working on further extensions to 3G standards, named Long Term Evolution and Ultra Mobile Broadband, respectively. Being based on an all Ip Network Infrastructur and using advanced wireless technologies such as MIMO, these specifications already display features characteristic for IMT - Advanced (4G), the successor of 3G. However, falling short of the bandwidth requirements for 4G (which is 1 Gbit/s for stationary and 100 Mbit/s for mobile operation), these standards are classified as 3.9G or Pre 4G.

3GPP plans to meet the 4G goals with LTE Advanced, whereas Qualcomm has halted development of UMB in favour of the LTE family.

On December 14, 2009 Telia Sonera announced in an official press release that "We are very proud to be the first operator in the world to offer our customers 4G services.With the launch of their network, initially they are offering services in Stockholm, Sweden and Oslo, Norway.

Universal Plug and Play

2009-11-24T06:48:00.000-08:00

Universal Plug and Play (UPnP) is a set of networking protocols promulgated by the UPnP forum. The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home (data sharing, communications, and entertainment) and in corporate environments for simplified installation of computer components. UPnP achieves this by defining and publishing UPnP device control protocols (DCP) built upon open, Internet-based communication standards.

The term UPnP is derived from plug and play, a technology for dynamically attaching devices directly to a computer, although UPnP is not directly related to the earlier plug-and-play technology. UPnP devices are "plug-and-play" in that when connected to a network they automatically announce their network address and supported device and services types, enabling clients that recognize those types to immediately begin using the device.

Overview

The UPnP architecture allows peer-to-peer networking of PCS, networked home appliance, CEwirelless devices. It is a distributed, open architecture protocol based on established standards such as TCP/IP, UDP, HTTP, XML, and SOAP. devices and

The UPnP architecture supports zero-configuration networking. A UPnP compatible device from any vendor can dynamically join a network, obtain an IP address, announce its name, convey its capabilities upon request, and learn about the presence and capabilities of other devices. DHCPDNS servers are optional and are only used if they are available on the network. Devices can leave the network automatically without leaving any unwanted state information behind. and

UPnP was published as a 73-part international standard, ISO/IEC 29341, in December, 2008.

Other UPnP features include:

Media and device independence: UPnP technology can run on many media that support IP including ethernet, fire wire, IR (IRda), home wiring (G.Hn) and RF (Bluetooth, WiFi). No special device driver support is necessary; common protocols are used instead.
UI Control: UPnP architecture enables devices to present a user interface through a web browser
Operating system and programming language independence: Any operating system and any programming language can be used to build UPnP products. UPnP does not specify or constrain the design of an API for applications running on control points; OS vendors may create APIs that suit their customer's needs.
Programmatic control: UPnP architecture also enables conventional application programmatic control.
Extensibility: Each UPnP product can have device-specific services layered on top of the basic architecture. In addition to combining services defined by UPnP Forum in various ways, vendors can define their own device and service types, and can extend standard devices and services with vendor-defined actions, state variables, data structure elements, and variable values.

Addressing

The foundation for UPnP networking is IP addressing. Each device must have a Dynamic Host Configuration Protocol (DHCP) client and search for a DHCP server when the device is first connected to the network. If no DHCP server is available, that is, the network is unmanaged, the device must assign itself an address. The process by which a UPnP device assigns itself an address is known within the UPnP Device Architecture as "AutoIP". In UPnP Device Architecture Version 1.0, AutoIP is defined within the specification itself; in UPnP Device Architecture Version 1.1, AutoIP references IETF RFC 3927. If during the DHCP transaction, the device obtains a domain name, for example, through a DNS server or via DNS fordwarding, the device should use that name in subsequent network operations; otherwise, the device should use its IP address.

Discovery

Given an IP address, the first step in UPnP networking is Discovery. The UPnP discovery protocol, defined in Section 1 of the UPnP Device Architecture, is known as the Simple Service Discovery Protocol (SSDP). When a device is added to the network, SSDP allows that device to advertise its services to control points on the network. Similarly, when a control point is added to the network, SSDP allows that control point to search for devices of interest on the network. The fundamental exchange in both cases is a discovery message containing a few, essential specifics about the device or one of its services, for example, its type, identifier, and a pointer to more detailed information.

Description

After a control point has discovered a device, the control point still knows very little about the device. For the control point to learn more about the device and its capabilities, or to interact with the device, the control point must retrieve the device's description from the URL provided by the device in the discovery message. The UPnP description for a device is expressed in XML and includes vendor-specific, manufacturer information like the model name and number, serial number, manufacturer name, URLs to vendor-specific web sites, etc. The description also includes a list of any embedded devices or services, as well as URLs for control, eventing, and presentation. For each service, the description includes a list of the commands, or actions, to which the service responds, and parameters, or arguments, for each action; the description for a service also includes a list of variables; these variables model the state of the service at run time, and are described in terms of their data type, range, and event characteristics

Control

Having retrieved a description of the device, the control point can send actions to a device's service. To do this, a control point sends a suitable control message to the control URL for the service (provided in the device description). Control messages are also expressed in XML using the Simple Object Access Protocol (SOAP). Much like function calls, the service returns any action-specific values in response to the control message. The effects of the action, if any, are modeled by changes in the variables that describe the run-time state of the service.

Event notification

The next step in UPnP networking is event notification, or "eventing". The event notification protocol defined in the UPnP Device Architecture is known as GENA, an acronym for "General Event Notification Architecture". A UPnP description for a service includes a list of actions the service responds to and a list of variables that model the state of the service at run time. The service publishes updates when these variables change, and a control point may subscribe to receive this information. The service publishes updates by sending event messages. Event messages contain the names of one or more state variables and the current value of those variables. These messages are also expressed in XML. A special initial event message is sent when a control point first subscribes; this event message contains the names and values for all evented variables and allows the subscriber to initialize its model of the state of the service. To support scenarios with multiple control points, eventing is designed to keep all control points equally informed about the effects of any action. Therefore, all subscribers are sent all event messages, subscribers receive event messages for all "evented" variables that have changed, and event messages are sent no matter why the state variable changed (either in response to a requested action or because the state the service is modeling changed).

Presentation

The final step in UPnP networking is presentation. If a device has a URL for presentation, then the control point can retrieve a page from this URL, load the page into a web browser, and depending on the capabilities of the page, allow a user to control the device and/or view device status. The degree to which each of these can be accomplished depends on the specific capabilities of the presentation page and device.

UPnP AV standards

UPnP AV stands for UPnP Audio and Video. On 12 July 2006 the UPnP Forum announced the release of version 2 of the UPnP Audio and Video specifications (UPnP AV v2), with new MediaServer version 2.0 and MediaRenderer version 2.0 classes. These enhancements are created by adding capabilities to the UPnP AV Media Server and MediaRenderer device classes that allow a higher level of interoperability between MediaServers and MediaRenderers from different manufacturers. Some of the early devices complying with these standards were marketed by Phillips under the Streamium brand name.

The UPnP AV standards have been referenced in specifications published by other organizations including Digital Living Network Alliance Networked Device Interoperability Guidelines,International Electrotechnical Commision IEC 62481-1, and Cable Televison Laboratories Open CAble Home Networking Protocol

UPnP AV components

UPnP MediaServer DCP - which is the UPnP-server (a 'master' device) that media library information and streams media-data (like audio/video/picture/files) to UPnP-clients on the network.
UPnP MediaServer ControlPoint - which is the UPnP-client (a 'slave' device) that can auto-detect UPnP-servers on the network to browse and stream media/data-files from them.
UPnP MediaRenderer DCP - which is a 'slave' device that can render (play) content.
UPnP RenderingControl DCP - control MediaRenderer settings; volume, brightness, RGB, sharpness, and more).
UPnP Remote User Interface (RUI) client/server - which sends/receives control-commands between the UPnP-client and UPnP-server over network, (like record, schedule, play, pause, stop, etc.).
- Web4CE (CEA 2014) for UPnP Remote UI- CEA-2014 standard designed by Consumer Electronic Association's R7 Home Network Committee. Web-based protocol and framework for Remote User Interface on UPnP networks and the internet interface (display and control options) as a web page to display on any other device connected to the home network. That means that you can control a home networking browser-based communications method for CE Devices on a UPnP home network using ethernet and a special version of HTML called CE-HTML. (Web4CE). This standard allows a UPnP-capable home network device to provide its device through any
QoS (Quality of Service) - is an important (but not mandatory) service function for use with UPnP AV (Audio and Video). QoS(Quality of Service) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program. Since UPnP AV is mostly to deliver streaming media that is often near-real time or real-time audio/video data which it is critical to be delivered within a specific time or the stream is interrupted.Quality of Services guarantees are especially important if the network capacity is limited, for example public networks, like the internet.
Quality of Services for UPnP consist of Sink Device (client-side/front-end) and Source Device (server-side/back-end) service functions. With classes such as; Traffic Class that indicates the kind of traffic in the traffic stream, (for example, audio or video). Traffic Identifier (TID) which identifies data packets as belonging to a unique traffic stream. Traffic Specification (TSPEC) which contains a set of parameters that define the characteristics of the traffic stream, (for example operating requirement and scheduling). Traffic Stream (TS) which is a unidirectional flow of data that originates at a source device and terminates at one or more sink device(s).

NAT traversal

One solution for Network Address Transmission traversal, called the Internet Gateway Protocol, is implemented via UPnP. Many routers and firewalls expose themselves as Internet Gateway Devices, allowing any local UPnP controller to perform a variety of actions, including retrieving the external IP address of the device, enumerate existing port mappings, and adding and removing port mappings. By adding a port mapping, a UPnP controller behind the IGD can enable traversal of the IGD from an external address to an internal client.

Problems with UPnP

Lack of Default Authentication

The UPnP protocol, as default, does not implement any authentication, so UPnP device implementations must implement their own authentication mechanisms, or implement the Device Security Service.There also exists a non-standard solution called UPnP-UP (Universal Plug and Play - User Profile) which proposes an extension to allow user authentication and authorization mechanisms for UPnP devices and applications.

Unfortunately, many UPnP device implementations lack authentication mechanisms, and by default assume local systems and their users are completely trustworthy.

Most notably, routers and firewalls running the UPnP IGD protocol are vulnerable to attack since the framers of the IGD implementation omitted a standard authentication method. For example, Adobe Flash programs are capable of generating a specific type of HTTP request. This allows a router implementing the UPnP IGD protocol to be controlled by a malicious web site when someone with a UPnP-enabled router simply visits that web site.The following changes can be made silently by code embedded in an Adobe Flash object hosted on a malicious website

Port fordward internal services (ports) to the router external facing side (i.e. expose computers behind a firewall to the Internet).
Port fordward the router's web administration interface to the external facing side.
Port forwarding to any external server located on the Internet, effectively allowing an attacker to attack an Internet host via the router, while hiding their IP address.
Change DNS server settings so that when victims believe they are visiting a particular site (such as an on-line bank), they are redirected to a malicious website instead.
Change the DNS server settings so that when a victim receives any software updates (from a source that isn't properly verified via some other mechanism, such as a checking a digital certificate has been signed by a trusted source), they download malicious code instead.
Change administrative credentials to the router/firewall.
Change PPP settings.
Change IP settings for all interfaces.
Change WiFi settings.
Terminate connections.

This only applies to the " firewall-hole-punching"-feature of UPnP ; it does not apply when the IGD does not support UPnP or UPnP has been disabled on the IGD. Also, not all routers can have such things as DNS server settings altered by UPnP because much of the specification (including LAN Host Configuration) is optional for UPnP enabled routers

Other Issues

UPnP uses HTTP over UDP (known as HTTPU and HTTPMU for unicast and multicast), even though this is not standardized and is specified only in an Internet-Draft that expired in 2001.
UPnP does not have a lightweight authentication protocol, while the available security protocols are complex. As a result, some UPnP devices ship with UPnP turned off by default as a security measure.

Future developments

UPnP continues to be actively developed. In fall 2008, the UPnP forum ratified the successor to UPnP 1.0, UPnP 1.1.

The standard DPWS was a candidate successor for UPnP, but UPnP 1.1 was selected by the forum.

UPnP InternetGatewaydevice's WANIPConnection service do have competitive solution known as NAT-PMP, is an IETF draft introduced by Apple inc. in 2005. However, NAT-PMP is focused only in NAT traversal. UPnP InternetGatewayDevice is currently being evolved to version 2 which preliminary content can be found from

Plug and play

2009-11-24T06:45:00.000-08:00

In computing, plug and play is a term used to describe the characteristic of a computer bust, or device specification, which facilitates the discovery of a hardware component in a system, without the need for physical device configuration, or user intervention in resolving resource conflicts.

Plug and play refers to both the traditional boot-time assignment of device resources and driver identification, as well as to hotplug systems such as USB and firewire

History of Device Configuration

In the beginnings of computing technology, the hardware logic was just a collection of building blocks, and the relationships between them had to be completely redesigned to accommodate different calculating operations. These changes were usually done by connecting some wires between modules and disconnecting others. The very earliest of mechanical computing devices such as the IBM punchcard accounting, tabulating and interpreting machines were programmed entirely in this manner, by the use of a quick-swap control panel wired to route signals between configuration sockets.

As general purpose computing devices developed, these connections and disconnections were instead used to specify locations in the system address spacecentral processing unit. If two or more of the same device were installed in one computer, it would be necessary to assign the second device to a separate, non-overlapping region of the system address space so that both could be accessible at the same time. where an expansion device should appear, in order for the device to be accessible by the

Some early microcomputing devices such as the Apple II required the end-user to physically cut some wires and solder others together to make these configuration changes. The changes were intended to be mostly permanent for the life of the hardware.

Over time the need developed for more frequent changes and for easier changes to be made by unskilled computer users. Rather than cutting and soldering connections, the header and jumper was developed. The header consists of two or more vertical pins arranged in an evenly-spaced grid. The jumper is a small conductive strip of metal clipped across the header pins. The conductive jumper strip is commonly encased in a plastic shell to help prevent electrical shorting between adjacent jumpers.

Jumpers have the unfortunate property of being easy to misplace if not needed, and are difficult to grasp in order to remove them from headers. To help make these changes easier, the DIP switch DIP switch was developed, also known as a dual in-line package switch. The DIP switch has small either rocker or sliding switches enclosed in a plastic shell and usually numbered for easy reference. DIP switches usually come in units of four or eight switches; longer rows of switches can be made by combining two or more units. DIP switches are particularly useful where a long string of jumpers would be closely packed together or where four or more jumpers would be used in combination to configure one device function. DIP switches also have a particular advantage for configuration settings which are likely to be changed more frequently than once every few years. (Because of the inconvenience of setting them, jumpers are typically used for settings that are not expected to need to be changed unless the device is removed from one computer and installed in another, an infrequent occurrence for internal devices in consumer desktop PCs.)

As computing devices spread further out into the general population, there was ever greater pressure developing to automate this configuration process. One of the first major industry efforts towards self-configuration was done by IBM with the creation of their Personal System/2 line of computers using the micro channel architecture (MCA). This took a giant leap forward, as expansion devices had absolutely no jumpers or DIP switches.

However, IBM's first attempt at self-configuration had a few major problems. In an attempt to simplify device setup, every piece of hardware was issued with a disk containing a special file used to auto-configure the hardware to work with the computer. (If the device required one or more drivers for specific operating systems, they were usually included on the same disk.) Without this disk the hardware would be completely useless and the computer would not boot at all until the unconfigured device was removed.

MCA also suffered for being a proprietary technology. Unlike their previous PC bus design, the AT bus, IBM did not publicly release specifications for MCA and actively pursued patents to block third parties from selling unlicensed implementations of it, and the developing PC Clone market did not want to pay royalties to IBM in order to use this new technology. The PC clone makers instead developed EISA, an extension to the existing old non-PnP AT bus standard, which they also further standardized and renamed ISA (to avoid IBM's "AT" trademark). With few vendors other than IBM supporting it with computers or cards, MCA eventually failed in the marketplace. Most vendors of PC-compatibles stayed largely with ISA and manual configuration, while EISA offered the same type of auto-configuration featured in MCA. (EISA cards required a configuration file as well.)

In time, many ISA cards incorporated, through proprietary and varied techniques, hardware to self-configure or to provide for software configuration; often the card came with a configuration program on disk that could automatically set the software-configurable (but not itself self-configuring) hardware. Some cards had both jumpers and software-configuration, with some settings controlled by each; this compromise reduced the number of jumpers that had to be set, while avoiding great expense for certain settings, e.g. nonvolatile registers for a base address setting. The problems of required jumpers continued on but slowly diminished as more and more devices, both ISA and other types, included extra self-configuration hardware. However, these efforts still did not solve the problem of making sure the end-user has the appropriate software driver for the hardware.

Internet Protocol Suite

2009-11-24T06:41:00.000-08:00

The Internet Protocol Suite (commonly known as TCP/IP) is the set of communications protocols Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard. Today's IP networking represents a synthesis of several developments that began to evolve in the 1960s and 1970s, namely the Internet and LANs, which emerged in the mid- to late-1980s, together with the advent of the World Wide Web in the early 1990s. used for the

The Internet Protocol Suite, like many protocol suites, may be viewed as a set of layers. Each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocol to translate data into forms that can eventually be physically transmitted.

The TCP/IP model consists of four layers.From lowest to highest, these are the link layer, the internet layer, the transport layer, and the application layer

History

The Internet Protocol Suite resulted from research and development conducted by the Defense Advanced Research Projects Agency (DARPA) in the early 1970s. After initiating the pioneering APARNET in 1969, DARPA started work on a number of other data transmission technologies. In 1972, Robert E. Kahn joined the DARPA Information Processing Technology Office, where he worked on both satellite packet networks and ground-based radio packet networks, and recognized the value of being able to communicate across both. In the spring of 1973, Vinton Cerf, the developer of the existing ARPANET network control program (NCP) protocol, joined Kahn to work on open-architecture interconnection models with the goal of designing the next protocol generation for the ARPANET.

By the summer of 1973, Kahn and Cerf had worked out a fundamental reformulation, where the differences between network protocols were hidden by using a common internetwork protocol, and, instead of the network being responsible for reliability, as in the ARPANET, the hosts became responsible. Cerf credits Hubert Zimmerman and Louis Pouzin, designer of the CYCLADES network, with important influences on this design.

The design of the network included the recognition that it should provide only the functions of efficiently transmitting and routing traffic between end nodes and that all other intelligence should be located at the edge of the network, in the end nodes. Using a simple design, it became possible to connect almost any network to the ARPANET, irrespective of their local characteristics, thereby solving Kahn's initial problem. One popular saying has it that TCP/IP, the eventual product of Cerf and Kahn's work, will run over "two tin cans and a string."

A computer called a router is provided with an interface to each network, and forwards packets back and forth between them. Requirements for routers are defined in (Request for Comments 1812).

The idea was worked out in more detailed form by Cerf's networking research group at Stanford in the 1973–74 period, resulting in the first TCP specification . (The early networking work at Xerox PARC, which produced the PARC Universal Packet protocol suite, much of which existed around the same period of time, was also a significant technical influence; people moved between the two.)

DARPA then contracted with BBN Technologies,Stanford University,and the University College London to develop operational versions of the protocol on different hardware platforms. Four versions were developed: TCP v1, TCP v2, a split into TCP v3 and IP v3 in the spring of 1978, and then stability with TCP/IP v4 — the standard protocol still in use on the Internet today.

In 1975, a two-network TCP/IP communications test was performed between Stanford and University College London (UCL). In November, 1977, a three-network TCP/IP test was conducted between sites in the US, UK, and Norway. Several other TCP/IP prototypes were developed at multiple research centres between 1978 and 1983. The migration of the ARPANET to TCP/IP was officially completed on January 1, 1983, when the new protocols were permanently activated.

In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. In 1985, the Internet Architecture Board held a three day workshop on TCP/IP for the computer industry, attended by 250 vendor representatives, promoting the protocol and leading to its increasing commercial use.

Layers in the Internet Protocol Suite

The concept of layers

The TCP/IP suite uses encapsulation to provide abstraction of protocols and services. Such encapsulation usually is aligned with the division of the protocol suite into layers of general functionality. In general, an application (the highest level of the model) uses a set of protocols to send its data down the layers, being further encapsulated at each level.

This may be illustrated by an example network scenario, in which two Internet host computers communicate across local network boundaries constituted by their internetworking gateways (routers).

TCP/IP stack operating on two hosts connected via two routers and the corresponding layers used at each hop

Encapsulation of application data descending through the protocol stack.

The functional groups of protocols and methods are the application layer, the transport layer, the internet layer, and the link layer. It should be noted that this model was not intended to be a rigid reference model into which new protocols have to fit in order to be accepted as a standard.

Different authors have interpreted the RFCs differently regarding the question whether the Link Layer (and the TCP/IP model) covers physical layer issues, or if a hardware layer is assumed below the Link Layer. Some authors have tried to use other names for the Link Layer, such as network interface layer, in view to avoid confusion with the data link layer of the seven layer OSI model. Others have attempted to map the Internet Protocol model onto the OSI Model. The mapping often results in a model with five layers where the Link Layer is split into a Data Link Layer on top of a Physical Layer. In literature with a bottom-up approach to Internet communication, in which hardware issues are emphasized, those are often discussed in terms of Physical Layer and Data Link Layer.

The Internet Layer is usually directly mapped into the OSI Model's network layer, a more general concept of network functionality. The Transport Layer of the TCP/IP model, sometimes also described as the host-to-host layer, is mapped to OSI Layer 4 (Transport Layer), sometimes also including aspects of OSI Layer 5 functionality. OSI's application layer,presentation layer, and the remaining functionality of the Session Layer are collapsed into TCP/IP's Application Layer. The argument is that these OSI layers do usually not exist as separate processes and protocols in Internet applications.

However, the Internet protocol stack has never been altered by the Internet Engineering Task Force from the four layers defined in RFC 1122. The IETF makes no effort to follow the OSI model although RFCs sometimes refer to it. The IETF has repeatedly stated that Internet protocol and architecture development is not intended to be OSI-compliant.

R RFC 2439, addressing Internet architecture, contains a section entitled: "Layering Considered Harmful".

Implementations

Most operating systems in use today, including all consumer-targeted systems, include a TCP/IP implementation.

Unique implementations include Lightweight TCP/IP, an open source stack designed for embedded systems and KA9Q NOS, a stack and associated protocols for amateur packet raiopersonal computer connected via serial lines. systems and

What is Broadband

2009-11-23T05:38:00.000-08:00

In telecommunication

Broadband in telecommunication refers to a signaling method that includes or handles a relatively wide range (or band) of frequencies, which may be divided into channels or frequency bins. Broadband is always a relative term, understood according to its context. The wider the bandwith, the greater the information-carrying capacity. In radio, for example, a very narrow-band signal will carry Morse code; a broader band will carry speech; a still broader band is required to carry music audio frequency required for realistic sound reproduction. A analog modem over the same telephone line a bandwidth of several megabits per second can be handled by ASDL, which is described as broadband (relative to a modem over a telephone line, although much less than can be achieved over a fiber optic circuit). without losing the high antenna described as "normal" may be capable of receiving a certain range of channels; one described as "broadband" will receive more channels. In data communications an will transmit a bandwidth of 56 kilobits per seconds (kbit/s) over a

In data communications

Broadband in data can refer to broadband network or broadband internet and may have the same meaning as above, so that data transmission over a fiber optic cable would be referred to as broadband as compared to a telephone modem operating at 56000 bite per second. However, a worldwide standard for what level of bandwidth and network speeds actually constitute Broadband has not been determined.

However, broadband in data commuication is frequently used in a more technical sense to refer to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission, regardless of data signaling rate. In network engineering this term is used for methods where two or more signals share a medium.Broadband Internet access, often shortened to just broadband, is a high data rate Internet access—typically contrasted with dial-up access using a 56k modem.

Dial-up modems are limited to a bitrate of less than 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply more than double this rate and generally without disrupting telephone use.

In DSL

The various forms of DSL services are broadband in the sense that digital information is sent over a high-bandwidth channel (located above the baseband voice channel on a single pair of wires).

In Ethernet

A baseband transmission sends one type of signal using a medium's full bandwidth, as in 100BASE-T Ethernet. Ethernet, however, is the common interface to broadband modems such as DSL data links, and has a high data rate itself, so is sometimes referred to as broadband. Ethernet provided over cable modem is a common alternative to DSL.

In power-line communication

Power Line have also been used for various types of data communication. Although some systems for remote control are based on narrowband signaling, modern high-speed systems use broadband signaling to achieve very high data rates. One example is the ITU-T G.hn standard, which provides a way to create a high-speed (up to 1 Gigabit/s). LAN using existing home wiring (including power lines, but also phone lines and coaxial cable).

In video

Broadband in analog video distribution is traditionally used to refer to systems such as cable television, where the individual channels are modulated on carriers at fixed frequencies.In this context, baseband is the term's antonym, referring to a single channel of analog video, typically in composite form with an audio subcarrier.The act of demodulating converts broadband video to baseband video.

However, broadband video in the context of streaming internet video has come to mean video files that have bitrates high enough to require broadband internet access in order to view them.

Broadband video is also sometimes used to describe IPTV Video on demand

Internet Popularity

2009-11-22T02:26:00.000-08:00

A CEA study in 2006 found that dial-up Internet access is on a notable decline in the U.S. In 2000, dial-up Internet connections accounted for 74% of all U.S. residential Internet connections. The US demographic pattern for (dial-up modem users per capita) has been more or less mirrored in Canada and Australia for the past 20 years.

Dial-up modem use in the US had dropped to 60% by 2003, and in 2006 stood at 36%. Voiceband modems were once the most popular means of internet access in the U.S., but with the advent of new ways of accessing the Internet, the traditional 56K modem is losing popularity.

Voice Modem

2009-11-22T02:25:00.002-08:00

Voice modems are regular modems that are capable of recording or playing audio over the telephone line. They are used for telephony applications. See Voice modem command set for more details on voice modems. This type of modem can be used as FXO card for Private branch exchange systems (compare V.92).

Deep-space Telecommunications

2009-11-22T02:25:00.001-08:00

Many modern modems have their origin in dees space telecommunication systems of the 1960s.

Differences with deep space telecom modems vs landline modems

digital modulation formats that have high doppler immunity are typically used
waveform complexity tends to be low, typically binary phase shift keying
error correction varies mission to mission, but is typically much stronger than most landline modems

Home networking

2009-11-22T02:24:00.001-08:00

Although the name modem is seldom used in this case, modems are also used for high-speed home networking applications, specially those using existing home wiring. One example is the G.HnlTU-T, which provides a high-speed (up to 1 Gbit/s) Local Area Network using existing home wiring (power lines, phone lines and coaxial cables). G.hn devices use OFDM to modulate a digital signal for transmission over the wire.

Broadband

2009-11-22T02:23:00.000-08:00

ASDL modems, a more recent development, are not limited to the telephone's voiceband audio frequencies. Some ASDL modems use coded orthogonal frequency division modulation (DMT).

Cable Modems use a range of frequencies originally intended to carry RF television channels. Multiple cable modems attached to a single cable can use the same frequency band, using a low-level media access protocol to allow them to work together within the same channel. Typically, 'up' and 'down' signals are kept separate using frequency division multiple access.

New types of broadband modems are beginning to appear, such as doubleway satellite and power line modems.

Broadband modems should still be classed as modems, since they use complex waveforms to carry digital data. They are more advanced devices than traditional dial-up modems as they are capable of modulating/demodulating hundreds of channels simultaneously.

Many broadband modems include the functions of a router (with ethernet and WiFiports) and other features such as DHCP, NAT and firewall features.

When broadband technology was introduced, networking and routers were unfamiliar to consumers. However, many people knew what a modem was as most internet access was through dial-up. Due to this familiarity, companies started selling broadband modems using the familiar term modem rather than vaguer ones like adapter or transceiver.

Many broadband modems must be configured in bridge mode before they can use a router.

Mobile Modems and Routers

2009-11-22T02:21:00.000-08:00

Modems which use mobile phone lines (UMTS,HDSPA,EVDO,WiMax), are known as Cellular Modems. Cellular modems can be embedded inside a laptop or appliance, or they can be external to it. External cellular modems are datacards and cellular routers. The datacard is a PC Card or Express Card which slides into a PCMIA/PC Card/Express Card slot on a computer. The most famous brand of cellular modem datacards is the Air Card made by Sierra Wireless. (Many people just refer to all makes and models as AirCards, when in fact this is a trademarked brand name.) Nowadays, there are USB cellular modems as well that use a USB port on the laptop instead of a PC Card or Express Card slot. A cellular routers may or may not have an external datacard (AirCard) that slides into it. Most cellular routers do allow such datacards or USB modems, except for the WAAV,Inc.CM3 mobile broadband cellular routers. Cellular Routers may not be modems per se, but they contain modems or allow modems to be slid into them. The difference between a cellular routers and a cellular modems is that a cellular router normally allows multiple people to connect to it (since it can route, or support multipoint to multipoint connections), while the modem is made for one connection.

Most of the GSM cellular modems come with an integrated SIM Cardholder (i.e., Sierra 881, etc.) The CDMA (EVDO) versions do not use SIM Cards, but use Electronic Serial Number instead.

The cost of using a cellular modem varies from country to country. Some carriers implement flat rate plans for unlimited data transfers. Some have caps (or maximum limits) on the amount of data that can be transferred per month. Other countries have plans that charge a fixed rate per data transferred—per megabyte or even kilobyte of data downloaded; this tends to add up quickly in today's content-filled world, which is why many people are pushing for flat data rates.

The faster data rates of the newest cellular modem technologies (UMTS,HDSPA,EVDO,WiMax) are also considered to be broadband cellular modems and compete with other Broadband modems below.

WiFi and WiMax

2009-11-22T02:20:00.001-08:00

Wireless Data Modem are used in the WiFi and WiMax standards, operating at microwave frequency

WiFi is principally used in laptops or notebook for Internet connections (wireless access point) and wireless application protocol(WAP).

Radio Modems

2009-11-22T02:19:00.001-08:00

Direct Broadcast Satelitte, Wi-Fi, and mobile phones all use modems to communicate, as do most other wireless services today. Modern telecommunications and data networks also make extensive use of radio modems where long distance data links are required. Such systems are an important part of the PSTN, and are also in common use for high-speed computer networks links to outlying areas where fibre is not economical.

Even where a cable is installed, it is often possible to get better performance or make other parts of the system simpler by using radio frequencies and modulation techniques through a cable. Coaxial cable has a very large bandwidth, however signal attenuation becomes a major problem at high data rates if a digital signal is used. By using a modem, a much larger amount of digital data can be transmitted through a single piece of wire. Digital cable television and cable Internet services use radio frequency modems to provide the increasing bandwidth needs of modern households. Using a modem also allows for frequency-division multiple access to be used, making full-duplex digital communication with many users possible using a single wire.

Wireless modems come in a variety of types, bandwidths, and speeds. Wireless modems are often referred to as transparent or smart. They transmit information that is modulated onto a carrier frequency to allow many simultaneous wireless communication links to work simultaneously on different frequencies.

Transparent modems operate in a manner similar to their phone line modem cousins. Typically, they were half duplex, meaning that they could not send and receive data at the same time. Typically transparent modems are polled in a round robin manner to collect small amounts of data from scattered locations that do not have easy access to wired infrastructure. Transparent modems are most commonly used by utility companies for data collection.

Smart modems come with a media access controller inside which prevents random data from colliding and resends data that is not correctly received. Smart modems typically require more bandwidth than transparent modems, and typically achieve higher data rates. The IEEE 802.11 standard defines a short range modulation scheme that is used on a large scale throughout the world.

List of Dial-up Speeds

2009-11-22T02:17:00.000-08:00

Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines).For a complete list see the companion article list if device bandwith . Please note baud == symbols per second.

Connection	Bitrate (kbit/s)
110 baud Bell 101 modem	0.1
300 baud	0.3
1200 bps (600 baud)	1.2
2400 bps (600 baud)	2.4
2400 bps (1,200 baud)	2.4
4800 bps (1,600 baud)	4.8
9600 bps (2,400 baud)	9.6
14.4 kbps (2,400 baud)	14.4
28.8 kbps (3,200 baud)	28.8
33.6 kbps (3,429 baud)	33.6
56 kbps (8,000/3,429 baud)	56.0/33.6
56 kbps (8,000/8,000 baud)	56.0/48.0
Bonding modem (two 56k modems)	112.0/96.0
Hardware compression (variable)	56.0-220.0
Hardware compression (variable)	56.0-320.0
Server-side web compression (variable)	100.0-1,000.0

Compression by the ISP

2009-11-22T02:14:00.001-08:00

As telephone-based 56k modems began losing popularity, some Internet Service Providers such as Netzero and Juno started using pre-compression to increase the throughput & maintain their customer base. As example, the Netscape ISP uses a compression program that squeezes images, text, and other objects at the server, just prior to sending them across the phone line. The server-side compression operates much more efficiently than the on-the-fly compression of V.44-enabled modems. Typically website text is compacted to 4% thus increasing effective throughput to approximately 1,300 kbit/s. The accelerator also pre-compresses Flash executables and images to approximately 30% and 12%, respectively.

The drawback of this approach is a loss in quality, where the graphics become heavily compacted and smeared, but the speed is dramatically improved such that web pages load in less than 5 seconds, and the user can manually choose to view the uncompressed images at any time. The ISPs employing this approach advertise it as "DSL speeds over regular phone lines" or simply "high speed dial-up".

Using Compression to Exceed 56k

2009-11-22T02:12:00.001-08:00

Today's V.42, V.42bis and V.44 standards allow the modem to transmit data faster than its basic rate would imply. For instance, a 53.3 kbit/s connection with V.44 can transmit up to 53.3*6 == 320 kbit/s using pure text. However, the compression ratio tends to vary due to noise on the line, or due to the transfer of already-compressed files (ZIP files, JPEG images, MP3 audio, MPEG video).At some points the modem will be sending compressed files at approximately 50 kbit/s, uncompressed files at 160 kbit/s, and pure text at 320 kbit/s, or any value in between.

In such situations a small amount of memory in the modem, a buffer, is used to hold the data while it is being compressed and sent across the phone line, but in order to prevent overflow of the buffer, it sometimes becomes necessary to tell the computer to pause the datastream. This is accomplished through hardware flow control using extra lines on the modem–computer connection. The computer is then set to supply the modem at some higher rate, such as 320 kbit/s, and the modem will tell the computer when to start or stop sending data.

PCM and Digital Lines

2009-11-22T02:10:00.002-08:00

In the late 1990s Rockwell and U.S. Robotics introduced new technology based upon the digital transmission used in modern telephony networks. The standard digital transmission in modern networks is 64 kbit/s but some networks use a part of the bandwidth for remote office signaling (eg to hang up the phone), limiting the effective rate to 56 kbit/s DSo. This new technology was adopted into ITU standards V.90 and is common in modern computers. The 56 kbit/s rate is only possible from the central office to the user site (downlink) and in the United States, government regulation limits the maximum power output to only 53.3 kbit/s. The uplink (from the user to the central office) still uses V.34 technology at 33.6k.

Later in V.92, the digital PCM technique was applied to increase the upload speed to a maximum of 48 kbit/s, but at the expense of download rates. For example a 48 kbit/s upstream rate would reduce the downstream as low as 40 kbit/s, due to echo on the telephone line. To avoid this problem, V.92 modems offer the option to turn off the digital upstream and instead use a 33.6 kbit/s analog connection, in order to maintain a high digital downstream of 50 kbit/s or higher.V.92 also adds two other features. The first is the ability for users who have call waiting to put their dial-up internet connection on hold for extended periods of time while they answer a call. The second feature is the ability to quickly connect to one's ISP. This is achieved by remembering the analog and digital characteristics of the telephone line, and using this saved information to reconnect at a fast pace.

ASVD (Digital Simultaneous Voice and Data)

2009-11-22T02:10:00.001-08:00

The V.61 Standard introduced Analog Simultaneous Voice and Data (ASVD). This technology allowed user's of v.61 modems to engage in point-to-point voice conversations with each other while their respective modems communicated.

In 1995, the first DSVD (Digital Simultaneous Voice and Data) modems became available to consumers, and the standard was ratified as v.70 by the International Telecommunication Union (ITU) in 1996.

Two DSVD modems can establish a completely digital link between each other over standard phone lines. Sometimes referred to as "the poor man's ISDN," and employing a similar technology, v.70 compatible modems allow for a maximum speed of 33.6 kbps between peers. By using a majority of the bandwidth for data and reserving part for voice transmission, DSVD modems allow users to pick up a telephone handset interfaced with the modem, and initiate a call to the other peer.

One practical use for this technology was realized by early two player video gamers, who could hold voice communication with each other while in game over the PSTN.

Advocates of DSVD envisioned whiteboard sharing and other practical applications for the standard, however, with advent of cheaper 56kbps analog modems intended for internet connectivity, peer-to-peer data transmission over the PSTN became quickly irrelevant. Also, the standard was never expanded to allow for the making or receiving of arbitrary phone calls while the modem was in use, due to the cost of infrastructure upgrades to telcos, and the advent of ISDN and DSL technologies which effectively accomplished the same goal.

Today, Multi-Tech is the only known company to continue to support a v.70 compatible modem. While their device also offers v.92 at 56kbps, it remains significantly more expensive than comparable modems sans v.70 support.

V.34/28.8k and 33.6k

2009-11-22T02:08:00.002-08:00

Any interest in these systems was destroyed during the lengthy introduction of the 28,800 bit/s V.34standard. While waiting, several companies decided to release hardware and introduced modems they referred to as V.FAST. In order to guarantee compatibility with V.34 modems once the standard was ratified (1994), the manufacturers were forced to use more flexible parts, generally a DSP and microcontroller, as opposed to purpose-designed ASIC modem chips.

Today, the ITU standard V.34 represents the culmination of the joint efforts. It employs the most powerful coding techniques including channel encoding and shape encoding. From the mere 4 bits per symbol (9.6 kbit/s), the new standards used the functional equivalent of 6 to 10 bits per symbol, plus increasing baud rates from 2,400 to 3,429, to create 14.4, 28.8, and 33.6 kbit/s modems. This rate is near the theoretical Shannon limit. When calculated, the Shannon capacity of a narrowband line is , with the signal-to-noise ratio. Narrowband phone lines have a bandwidth from 300-3,100 Hz, so using : capacity is approximately 35 kbit/s.

Without the discovery and eventual application of trellis modulation, maximum telephone rates would have been limited to 3,429 baud * 4 bit/symbol == approximately 14 kbit/s using traditional QAM.

Breaking the Barrier

2009-11-22T02:08:00.001-08:00

In 1980, Gottfried Ungerboeck from IBM Zurich Research Laboratory applied powerful channel coding techniques to search for new ways to increase the speed of modems. His results were astonishing but only conveyed to a few colleagues. Finally in 1982, he agreed to publish what is now a landmark paper in the theory of information coding.By applying powerful parity check coding to the bits in each symbol, and mapping the encoded bits into a two-dimensional diamond pattern, Ungerboeck showed that it was possible to increase the speed by a factor of two with the same error rate. The new technique was called mapping by set partitions (now known as trellis modulation).

Error Correcting Codes, which encode code words (sets of bits) in such a way that they are far from each other, so that in case of error they are still closest to the original word (and not confused with another) can be thought of as analogous to sphere packing or packing pennies on a surface: the greater two bit sequences are from one another, the easier it is to correct minor errors.

The industry was galvanized into new research and development. More powerful coding techniques were developed, commercial firms rolled out new product lines, and the standards organizations rapidly adopted to new technology. The tipping point occurred with the introduction of the Supra FAXModem14400 in 1991. Rockwell had introduced a new chipset supporting not only V.32 and MNP, but the newer 14,400 bit/s V3.2bis and the higher-compression V4.2bis as well, and even included 9,600 bit/s fax capability. Supra, then known primarily for their hard drive systems, used this chipset to build a low-priced 14,400 bit/s modem which cost the same as a 2,400 bit/s modem from a year or two earlier (about US$300). The product was a runaway best-seller, and it was months before the company could keep up with demand.

V.32bis was so successful that the older high-speed standards had little to recommend them. USR fought back with a 16,800 bit/s version of HST, while AT&T introduced a one-off 19,200 bit/s method they referred to as V.32ter (also known as V.32 terbo or tertiary), but neither non-standard modem sold well.

Compressions and Error Correction

2009-11-22T02:06:00.001-08:00

Operations at these speeds pushed the limits of the phone lines, resulting in high error rates. This led to the introduction of error correction systems built into the modems, made most famous with Microcom's MNP systems. A string of MNP standards came out in the 1980s, each increasing the effective data rate by minimizing overhead, from about 75% theoretical maximum in MNP 1, to 95% in MNP 4. The new method called MNP 5 took this a step further, adding data compression to the system, thereby increasing the data rate above the modem's rating. Generally the user could expect an MNP5 modem to transfer at about 130% the normal data rate of the modem. Details of MNP were later released and became popular on a series of 2,400-bit/s modems, and ultimately led to the development of V4.2 and V4.2bis ITU standards. V.42 and V.42bis were non-compatible with MNP but were similar in concept: Error correction and compression.

Another common feature of these high-speed modems was the concept of fallback, or speed hunting, allowing them to talk to less-capable modems. During the call initiation the modem would play a series of signals into the line and wait for the remote modem to respond to them. They would start at high speeds and progressively get slower and slower until they heard an answer. Thus, two USR modems would be able to connect at 9,600 bit/s, but, when a user with a 2,400-bit/s modem called in, the USR would fallback to the common 2,400-bit/s speed. This would also happen if a V.32 modem and a HST modem were connected. Because they used a different standard at 9,600 bit/s, they would fall back to their highest commonly supported standard at 2,400 bit/s. The same applies to V.32bis and 14,400 bit/s HST modem, which would still be able to communicate with each other at only 2,400 bit/s.

Echo Cancellation

2009-11-22T02:05:00.001-08:00

Echo Cancellation was the next major advance in modem design. Local telephone lines use the same wires to send and receive, which results in a small amount of the outgoing signal bouncing back. This signal can confuse the modem. Is the signal it is receiving a data transmission from the remote modem, or its own transmission bouncing back? This was why earlier modems split the signal frequencies into answer and originate; each modem simply didn't listen to its own transmitting frequencies. Even with improvements to the phone system allowing higher speeds, this splitting of available phone signal bandwith still imposed a half-speed limit on modems.

Echo cancellation got around this problem. Measuring the echo delays and magnitudes allowed the modem to tell if the received signal was from itself or the remote modem, and create an equal and opposite signal to cancel its own. Modems were then able to send over the whole frequency spectrum in both directions at the same time, leading to the development of 4,800 and 9,600 bit/s modems.

Increases in speed have used increasingly complicated communications theory. 1,200 and 2,400 bit/s modems used the phase shift key (PSK) concept. This could transmit two or three bits per symbol. The next major advance encoded four bits into a combination of amplitude and phase, known as Quadrature Amplitude Modulation (QAM). Best visualized as a constellation diagram, the bits are mapped onto points on a graph with the x (real) and y (quadrature) coordinates transmitted over a single carrier.

The new V.27ter and V.32 standards were able to transmit 4 bits per symbol, at a rate of 1,200 or 2,400 baud, giving an effective bit rate of 4,800 or 9,600 bit/s. The carrier frequency was 1,650 Hz. For many years, most engineers considered this rate to be the limit of data communications over telephone networks.

Increasing Speed (again)

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Many other standards were also introduced for special purposes, commonly using a high-speed channel for receiving, and a lower-speed channel for sending. One typical example was used in the French Minitel system, in which the user's terminals spent the majority of their time receiving information. The modem in the Minitel terminal thus operated at 1,200 bit/s for reception, and 75 bit/s for sending commands back to the severs.

Three U.S. companies became famous for high-speed versions of the same concept.TelebitTrailblazer modem in 1984, which used a large number of 36 bit/s channels to send data one-way at rates up to 18,432 bit/s. A single additional channel in the reverse direction allowed the two modems to communicate how much data was waiting at either end of the link, and the modems could change direction on the fly. The Trailblazer modems also supported a feature that allowed them to spoof the UUCP g protocol, commonly used on Unix systems to send e-mail, and thereby speed UUCP up by a tremendous amount. Trailblazers thus became extremely common on Unix systems, and maintained their dominance in this market well into the 1990s. introduced its

U.S Robotics (USR) introduced a similar system, known as HST, although this supplied only 9,600 bit/s (in early versions at least) and provided for a larger backchannel. Rather than offer spoofing, USR instead created a large market among Fidonet users by offering its modems to BBS syspops at a much lower price, resulting in sales to end users who wanted faster file transfers. Hayes was forced to compete, and introduced its own 9,600-bit/s standard, Express 96 (also known as Ping-Pong), which was generally similar to Telebit's PEP. Hayes, however, offered neither protocol spoofing nor sysop discounts, and its high-speed modems remained rare.

Increasing Speed

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The 300 bit/s modems used audio frequency-shift keying to send data. In this system the stream of 1s and 0s in computer data is translated into sounds which can be easily sent on the phone lines. In the Bell 103 system the originating modem sends 0s by playing a 1,070 Hz tone, and 1s at 1,270 Hz, with the answering modem putting its 0s on 2,025 Hz and 1s on 2,225 Hz. These frequencies were chosen carefully, they are in the range that suffer minimum distortion on the phone system, and also are not harmonics of each other.

In the 1,200 bit/s and faster systems, phase-shift keying was used. In this system the two tones for any one side of the connection are sent at the similar frequencies as in the 300 bit/s systems, but slightly out of phase. By comparing the phase of the two signals, 1s and 0s could be pulled back out, for instance if the signals were 90 degrees out of phase, this represented two digits, 1, 0, at 180 degrees it was 1, 1. In this way each cycle of the signal represents two digits instead of one. 1,200 bit/s modems were, in effect, 600 symbols per second modems (600 baud modems) with 2 bits per symbol.

Voiceband modems generally remained at 300 and 1,200 bit/s (V2.1 and V.22) into the mid 1980s. A V.22bis 2,400-bit/s system similar in concept to the 1,200-bit/s Bell 212 signalling was introduced in the U.S., and a slightly different one in Europe. By the late 1980s, most modems could support all of these standards and 2,400-bit/s operation was becoming common.

For more information on baud rates versus bit rates, see the companion article list of device bandwidths.

Dial-up Modem

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A standard modem of today contains two functional parts: an analog section for generating the signals and operating the phone, and a digital section for setup and control. This functionality is actually incorporated into a single chip, but the division remains in theory. In operation the modem can be in one of two modes, data mode in which data is sent to and from the computer over the phone lines, and command mode in which the modem listens to the data from the computer for commands, and carries them out. A typical session consists of powering up the modem (often inside the computer itself) which automatically assumes command mode, then sending it the command for dialing a number. After the connection is established to the remote modem, the modem automatically goes into data mode, and the user can send and receive data. When the user is finished, the escape sequence, "+++" followed by a pause of about a second, is sent to the modem to return it to command mode, and the command ATH to hang up the phone is sent.

The commands themselves are typically from the Hayes command set, although that term is somewhat misleading. The original Hayes commands were useful for 300 bit/s operation only, and then extended for their 1,200 bit/s modems. Faster speeds required new commands, leading to a proliferation of command sets in the early 1990s. Things became considerably more standardized in the second half of the 1990s, when most modems were built from one of a very small number of chipsets. We call this the Hayes command set even today, although it has three or four times the numbers of commands as the actual standard.

Winmodem

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A Winmodem or Softmodem is a stripped-down modem that replaces tasks traditionally handled in hardware with software. In this case the modem is a simple digital signal processor designed to create sounds, or voltage variations, on the telephone line. Softmodems are cheaper than traditional modems, since they have fewer hardware components. One downside is that the software generating the modem tones is not simple, and the performance of the computer as a whole often suffers when it is being used. For online gaming this can be a real concern. Another problem is lack of portability such that other OSes (such as Linux) may not have an equivalent driver to operate the modem.

The Smartmodem and the rise of BBSes

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The next major advance in modems was the Smartmodem, introduced in 1981 by Hayes Communications. The Smartmodem was an otherwise standard 103A 300-bit/s modem, but was attached to a small controller that let the computer send commands to it and enable it to operate the phone line. The command set included instructions for picking up and hanging up the phone, dialing numbers, and answering calls. The basic Hayes command set remains the basis for computer control of most modern modems.

Prior to the Hayes Smartmodem, dial-up modems almost universally required a two-step process to activate a connection: first, the user had to manually dial the remote number on a standard phone handset, and then secondly, plug the handset into an acoustic coupler. Hardware add-ons, known simply as dialers, were used in special circumstances, and generally operated by emulating someone dialing a handset.

With the Smartmodem, the computer could dial the phone directly by sending the modem a command, thus eliminating the need for an associated phone instrument for dialing and the need for an acoustic coupler. The Smartmodem instead plugged directly into the phone line. This greatly simplified setup and operation. Terminal programs that maintained lists of phone numbers and sent the dialing commands became common.

The Smartmodem and its clones also aided the spread of bulletin boards systems (BBSs). Modems had previously been typically either the call-only, acoustically coupled models used on the client side, or the much more expensive, answer-only models used on the server side. The Smartmodem could operate in either mode depending on the commands sent from the computer. There was now a low-cost server-side modem on the market, and the BBSs flourished.

Almost all modern modems also do double-duty as a fax machine as well. Digital faxes, introduced in the 1980s, are simply a particular image format sent over a high-speed (commonly 14.4 kbit/s) modem. Software running on the host computer can convert any image into fax-format, which can then be sent using the modem. Such software was at one time an add-on, but since has become largely universal.

Carterfone Decision

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For many years, the Bell System AT&T maintained a monopoly in the United States on the use of its phone lines, allowing only Bell-supplied devices to be attached to its network. Before 1968, AT&T maintained a monopoly on what devices could be electricallymechanically connected to the phone, through the handset, known as accoustically coupled modems. Particularly common models from the 1970s were the Novation CATAnderson-Jacobson, spun off from an in-house project at the Lawrence Livermore National Labortory. Hush-a-phone v.FCCwas a seminal ruling in Unites States telecommunications law decided by the DC Circuit Court of Appeals on November 8, 1956. The District Court found that it was within the FCC's authority to regulate the terms of use of AT&T's equipment. Subsequently, the FCC examiner found that as long as the device was not physically attached it would not threaten to degenerate the system. Later, in the Canterfone decision of 1968, the FCC passed a rule setting stringent AT&T-designed tests for electronically coupling a device to the phone lines. AT&T made these tests complex and expensive, so acoustically coupled modems remained common into the early 1980s. connected to its phone lines. This led to a market for 103A-compatible modems that were and the

In December 1972,Vadic introduced the VA3400. This device was remarkable because it provided full duplex operation at 1,200 bit/s over the dial network, using methods similar to those of the 103A in that it used different frequency bands for transmit and receive. In November 1976, AT&T introduced the 212A modem to compete with Vadic. It was similar in design to Vadic's model, but used the lower frequency set for transmission. It was also possible to use the 212A with a 103A modem at 300 bit/s. According to Vadic, the change in frequency assignments made the 212 intentionally incompatible with acoustic coupling, thereby locking out many potential modem manufacturers. In 1977, Vadic responded with the VA3467 triple modem, an answer-only modem sold to computer center operators that supported Vadic's 1,200-bit/s mode, AT&T's 212A mode, and 103A operation.

Modem Definitions

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A modem (modulator-demodulator) is a Device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from driven diodes to radio.

The most familiar example is a voiceband modem that turns the digital 1s and 0s of a personal computer into sounds that can be transmitted over the telephone lines of POTS, and once received on the other side, converts those 1s and 0s back into a form used by a USB, Ethernet, serial, or network connection.

Modems are generally classified by the amount of data they can send in a given time, normally measured in bits per second (bit/s, or bps). They can also be classified by Baud, the number of times the modem changes its signal state per second.

Faster modems are used by Internet users every day, notably cable modems and ASDL Modems. In telecommunication, wide-band radio modems transmit repeating frames of data at very high data rates over microwaves radio links. Narrow-band radio modem is used for low data rate up to 19.2k mainly for private radio networks. Some microwave modems transmit more than a hundred million bits per second.Optical modem transmit data over optical fibers. Most intercontinental data links now use optical modems transmitting over undersea optical fibers. Optical modems routinely have data rates in excess of a billion (1x10⁹) bits per second. One kilobit per second (kbit/s, kb/s, or kbps) as used in this article means 1000 bites per second and not 1024 bites per second. For example, a 56k modem can transfer data at up to 56,000 bit/s (7 kB/s) over the phone line.

In the summer of 1960, the name Data-Phone was introduced to replace the earlier term digital subset. The 202 Data-Phone was a half duplex asynchronous service that was marketed extensively in late 1960. In 1962, the 201A and 201B Data-Phones were introduced. They were synchronous modems using two-bit-per-baud phase shift keyingfull duplex 2,400 bit/s service on four-wire leased lines, the send and receive channels running on their own set of two wires each. (PSK). The 201A operated half-duplex at 2,000 bit/s over normal phone lines, while the 201B provided

The famous Bell 103A dataset standard was also introduced by Bell Labs in 1962. It provided full-duplex service at 300 baud over normal phone lines. Frequency shift keyingHz and the answering modem transmitting at 2,025 or 2,225 Hz. The readily available 103A2 gave an important boost to the use of remote low-speed terminals such as the KSR33, the ASR33, and the IBM 2741. AT&T reduced modem costs by introducing the originate-only 113D and the answer-only 113B/C modems. was used with the call originator transmitting at 1,070 or 1,270