That name is based on the abbreviation for time division multiple access, a common multiple access technique which is used by multiple protocols, including GSM, as well as in IS-54 and IS-136.

IS-54 is the first mobile communication system which had provision for security, and the first to employ TDMA technology.

Another name for IS-54 is United States Digital Cellular ( USDC ).

The access method used for IS-54 is Time Division Multiple Access ( TDMA ), which was the first U. S. digital standard to be developed.

The IS-54 system has different synchronization sequences for each of the six time slots making up the frame, thereby allowing each receiver to synchronize to its own preassigned time slots.

The modulation scheme for IS-54 is 7C / 4 differential quaternary phase shift keying ( DQPSK ), otherwise known as differential 7t / 4 4-PSK or π / 4 DQPSK.

IS-54 uses the CAVE ( Cellular Authentication, Voice Privacy and Encryption ) algorithm for authentication and the CMEA ( Cellular Message Encryption Algorithm ) for encryption.

The IS-54 standard specifies 84 control channels, 42 of which are shared with AMPS.

The ANSI designation of IS-54 is ANSI / TIA / EIA-627, but this standard is still popularly referred to as IS-54.

Time Division Multiple Access or TDMA was initially defined by the IS-54 standard and is now specified in the IS-13x series of specifications of the EIA / TIA.

IS-54 security features is also a matter of interest as it was the first standard to specify some security measures.

IS-54 and IS-136 are second-generation ( 2G ) mobile phone systems, known as Digital AMPS ( D-AMPS ).

* Digital AMPS ( IS-54 and IS-136 ), a 2G mobile-phone standard that uses Time division multiple access

The quest resulted in IS-54, the first American 2G standard.

The IS-54 VSELP standard was published by the Telecommunications Industry Association in 1989.

IS-54, on the other hand, increased capacity by digital means using TDMA protocols.

Using IS-54, a cellular carrier could convert any of its system's analog voice channels to digital.

IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data ( CSD ), and an improved compression protocol.

IS-54 maintains compatibility with Advanced Mobile Phone System ( AMPS ) in many ways.

IS-54 was, in fact, backward compatible with analog cellular and indeed co-exists on the same radio channels as AMPS.

IS-54 also supported authentication, a help in preventing fraud.

IS-54 employs the same 30 kHz channel spacing and frequency bands ( 824-849 and 869-894 MHz ) as AMPS.

To maintain compatibility with the existing AMPS cellular telephone system, the primary forward and reverse control channels in IS-54 cellular systems use the same signaling techniques and modulation scheme ( binary FSK ) as AMPS.

An AMPS / IS-54 infrastructure can support use of either analog AMPS phones or D-AMPS phones.

Variations of this codec have been used in several 2G cellular telephony standards, including IS-54, IS-136 ( D-AMPS ), GSM ( Half Rate speech ) and iDEN.

`` E '' stands for `` execution '' -- the moment a `` go order '' would unleash an American nuclear strike.

Cardboard noisemakers, substitutes for the unavailable tin models, were being hawked and bought at makeshift stands every few yards along Broadway, and one's ears were continually serenaded by the horns' rasps and bleats.

the attitudes of a U.N. delegate who experiences difficulty in finding adequate housing in New York City, or of a foreign diplomat in similar circumstances in our Capital, can easily be directed against the United States and all that it stands for.

More stands on the margins of modernity for one reason alone -- because he wrote Utopia.

Babe Ruth, as he always did in the Stadium, played right field to avoid having the sun in his eyes, and Tommy Thevenow, a rather mediocre hitter who played shortstop for the St. Louis Cardinals, knocked a ball with all his might into the sharp angle formed by the permanent stands and the wooden bleachers, where Ruth could not reach it.

water is Af and the H stands for hydrogen ; ;

Against this invincible determination to communize the whole world stands a group of nations unable to agree on fundamentals and each refusing to make any sacrifice of sovereignty for the common good of all.

For all practical purposes, the West stands disunited, undedicated, and unprepared for the tasks of world leadership.

Implements of wood and iron are available for close and hasty combat no matter where a man stands.

The others, the ones in the stands, were spellbound, for hearing the mayor was for them like listening to a symphony was for sophisticated folks in New York City.

There was a crowd in the stands for a change and the sun was hot.

John Philoponus stands out for having attempted a fundamental critique of Aristotle's views on the eternity of the world, movement, and other elements of Aristotelian thought.

The Canadian Aboriginal syllabics are also an abugida rather than a syllabary as their name would imply, since each glyph stands for a consonant which is modified by rotation to represent the following vowel.

An abjad is a type of writing system where each symbol always or usually stands for a consonant, leaving the reader to supply the appropriate vowel.

Alpha also stands for thermal expansion coefficient of a compound in physical chemistry.

The win-loss ratio in Ashes Tests ( up to and including the 2011 series ) stands at 123 wins for Australia to 100 wins for England, with 87 draws.

Ann Arbor was founded in 1824, with one theory stating that it is named after the spouses of the city's founders and for the stands of trees in the area.

There are various accounts concerning the origin of the settlement's name ; one states that Allen and Rumsey decided to name it for their wives, both named Ann, and for the stands of burr oak in the of land they purchased for $ 800 from the federal government at $ 1. 25 per acre.

** The L stands for Linux affinity

The " ST " officially stands for " Sixteen / Thirty-two ", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals.