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IMA Group (company)
Inverse Multiplexing for ATM (IMA) is a standardized technology used to transport ATM traffic over a bundle of T1 or E1 lines, which is called an ''IMA Group''. This allows for gradual increase in data link capacity where implementing a higher capacity solution like T3/E3 or SONET/SDH is not deemed feasible. The maximum number of lines in an IMA Group is 32, bringing the total data rate to roughly 64 Mbit/s. The standard specification was initially approved by The ATM Forum in July 1997, and was later updated to version 1.1 in March 1999. ATM cell insertion happens in the round robin fashion and is transparent for the terminal equipment on the ends of the link. IMA inverse multiplexing functionality requires some overhead (ICP or ''IMA Control Protocol'' cells, typically one ICP cell in every IMA frame—commonly 128 cells in length—and in CTC or ''Common Transmit Clock'' mode, an ICP ''stuff'' cell must be inserted after every 2048 cells), and an IMA sublayer on the phy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous Transfer Mode
Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of the Broadband Integrated Services Digital Network as defined in the late 1980s, and designed to integrate telecommunication networks. It can handle both traditional high-throughput data traffic and Real-time computing, real-time, low-latency content such as telephony (voice) and video.ATM Forum, The User Network Interface (UNI), v. 3.1, , Prentice Hall PTR, 1995, page 2. ATM is a cell switching technology, providing functionality that combines features of circuit switching and packet switching networks by using asynchronous communication, asynchronous time-division multiplexing.McDysan (1999), p. 287. ATM was seen in the 1990s as a competitor to Ethernet and networ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-carrier
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell System, and could transmit up to 24 telephone calls simultaneously over a single transmission line of copper wire. Subsequent specifications carried multiples of the basic T1 (1.544 Mbit/s) data rates, such as T2 (6.312 Mbit/s) with 96 channels, T3 (44.736 Mbit/s) with 672 channels, and others. Although a ''T2'' was defined as part of AT&T's T-carrier system, which defined five levels, T1 through T5, only the T1 and T3 were commonly in use.1999 ad: On the left, in an aisle seat, a man who very much "filled" his airline seat while on the right side of the aisle is a height-challenged man whose shoe toes barely reach the floor Transmission System 1 The T-carrier is a hardware specification for carrying multiple time-division m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E-carrier
The E-carrier is a member of the series of carrier systems developed for digital transmission of many simultaneous telephone calls by time-division multiplexing. The European Conference of Postal and Telecommunications Administrations (CEPT) originally standardised the E-carrier system, which revised and improved the earlier American T-carrier technology, and this has now been adopted by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). It was widely used in almost all countries outside the US, Canada, and Japan. E-carrier deployments have steadily been replaced by Ethernet as telecommunication networks transition towards all IP. E1 frame structure An E1 link operates over two separate sets of wires, usually unshielded twisted pair (balanced cable) or using coaxial (unbalanced cable). A nominal 3 volt peak signal is encoded with pulses using a method avoiding long periods without polarity changes. The line data rate is 2.048 Mbit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Line
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions. Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph, telephone, television, and radio. Early telecommunication networks used metal wires as the medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi, who won the 1909 Nobel Prize in Physics. Other early pioneers in electrical and electronic tel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Link
A data link is a means of telecommunications link, connecting one location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of data terminal equipment) and the interconnecting data telecommunication circuit. These are governed by a link protocol enabling digital data to be transferred from a data source to a data sink. Types There are at least three types of basic data-link configurations that can be conceived of and used: * Simplex communications, most commonly meaning all communications in one direction only. * Half-duplex communications, meaning communications in both directions, but not both ways simultaneously. * Duplex (telecommunications), Duplex communications, communications in both directions simultaneously. Aviation In civil aviation, a data-link system (known as Controller Pilot Data Link Communications) is use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SONET/SDH
Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates, data can also be transferred via an electrical interface. The method was developed to replace the plesiochronous digital hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without the problems of synchronization. SONET and SDH, which are essentially the same, were originally designed to transport circuit mode communications, e.g. DS1, DS3, from a variety of different sources. However, they were primarily designed to support real-time, uncompressed, circuit-switched voice encoded in PCM format. The primary difficulty in doing this prior to SONET/SDH was that the synchronization sources of these various circuits were different. This meant t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-robin Tournament
A round-robin tournament or all-play-all tournament is a competition format in which each contestant meets every other participant, usually in turn.''Webster's Third New International Dictionary of the English Language, Unabridged'' (1971, G. & C. Merriam Co), p.1980. A round-robin contrasts with an elimination tournament, wherein participants are eliminated after a certain number of wins or losses. Terminology The term ''round-robin'' is derived from the French term ('ribbon'). Over time, the term became idiomized to ''robin''. In a ''single round-robin'' schedule, each participant plays every other participant once. If each participant plays all others twice, this is frequently called a ''double round-robin''. The term is rarely used when all participants play one another more than twice, and is never used when one participant plays others an unequal number of times, as is the case in almost all of the major North American professional sports leagues. In the United Kingdom, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Equipment
In telecommunications, the term terminal equipment has the following meanings: * Communications equipment at either end of a communications link, used to permit the stations involved to accomplish the mission for which the link was established. * In radio- relay systems, equipment used at points where data are inserted or derived, as distinct from equipment used only to relay a reconstituted signal. * Telephone and telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas ... switchboards and other centrally located equipment at which communications circuits are terminated. See also * Customer-premises equipment * Data terminal equipment, an end instrument that converts user information into signals for transmission or reconverts the received signals into user information Referen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to transmit on, the line code to use and similar low-level parameters, are specified by the physical layer. At the electrical layer, the physical layer is commonly implemented in a dedicated PHY chip or, in electronic design automation (EDA), by a design block. In mobile computing, the MIPI Alliance *-PHY family of interconnect protocols are widely used. Role The physical layer defines the means of transmitting a stream of raw bits over a physical data link connecting network nodes. The bitstream may be grouped into code words or symbols and converted to a physical signal that is transmitted over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Multiplexer
An inverse multiplexer (often abbreviated to inverse MUX or IMUX) allows a data stream to be broken into multiple lower data rate communication links. An inverse multiplexer differs from a demultiplexer because the multiple output streams from the former stay inter-related, whereas those from the latter are unrelated. An inverse multiplexer is the opposite of a multiplexer in that it divides one high-speed link into multiple low-speed links, whereas a multiplexer combines multiple low-speed links into one high-speed link. This provides an end to end connection of several times the data rate available on each of the low rate data links. Note that, as with multiplexers, links are often used in bi-directional pairs and, at either end of the link, an inverse multiplexer will be combined with its reverse (an inverse demultiplexer) and still be called an ''inverse MUX''. Inverse multiplexers are used, for example, to combine a number of ISDN channels together into one high rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
