Let's Connect Our World

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

Read Users' Comments (0)

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.

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.

Read Users' Comments (0)

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

Read Users' Comments (0)

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

Read Users' Comments (0)

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.

Read Users' Comments (0)

Read Users' Comments (0)

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

Read Users' Comments (0)