Analogue Cellular Systems (AMPS)

Standards

AMPS is defined not by a single standard, but by many standards. All the standards are developed by the TR-45 committee within the TIA (Telecommunications Industry Association). Even the radio interfaces are defined by several families of standards, one for each technology (Analogue, NAMPS, TDMA and CDMA).

The AMPS family of wireless standards were intended to be just another analogue radio-telephone standard (e.g. Advanced Mobile Phone Service followed IMTS: Improved Mobile Telephone Service). However, due to the high capacity allowed by the cellular concept, the lower power which enabled portable operation and the robust design of AMPS by AT&T, AMPS has been a stunning success.

Today, more than half the cellular phones in the world operate according to AMPS standards, which, since 1988, have been maintained and developed by the Telecommunications Industry Association (TIA).

From its humble beginnings, AMPS has grown to accommodate TDMA and CDMA digital technology, narrowband analogue operation (NAMPS), in-building and residential modifications. Most recently, operation in the 1800-2000 Mhz PCS frequency band has been added to standards for CDMA, TDMA, narrowband analogue and soon, even plain old analogue. All of these additions have been done while maintaining an AMPS compatibility mode (known as BOA: Boring Old AMPS). It might be boring but it works, and the AMPS compatibility makes advanced phones work everywhere, even if all their features are not available.

Some of the major AMPS radio interface standards are:

IS-3 Analogue Cellular

The original analogue cellular standard now replaced by ANSI standard EIA/TIA-553 and TIA interim standard IS-91.

IS-54 TDMA Digital Cellular

A digital cellular system that squeezes three conversations into one cellular channel using Time Division Multiple Access technology. Future plans are for 6 conversations in one channel and, using digital speech interpolation, a further doubling of capacity.

IS-88 Narrowband Analogue Cellular

A Motorola developed system that squeezes three conversations into one cellular channel using analogue frequency division multiplexing. First standardised in TIA interim standard IS-88, and now incorporated in IS-91.

IS-91 Analogue Cellular and PCS

The TIA version of the analogue cellular standard, incorporating the functionality of

IS-88 (narrowband analogue) and

IS-94 as well as PCS band operation.

IS-94 Inbuilding Cellular

A standard for in-building operation of analogue cellular systems using extremely low power. Now incorporated in IS-91.

IS-95 CDMA Digital Cellular

A digital cellular system that squeezes between 10 and 20 conversations into one cellular channel by combining 30 khz cellular channels into a single 1.25 MHz channel and using code division multiplexing to combine and recover the individual conversations.

IS-136 TDMA Digital Cellular with Digital Control Channel

An enhancement to IS-54 TDMA, that includes a more advanced control channel (known as the digital control channel (DCCH), to distinguish it from the 'analogue' control channel, which although less sophisticated, is still digital!).

EIA/TIA-553 Analogue Cellular

The ANSI version of the analogue cellular standard. Generally one-step behind IS-91, and without support for NAMPS.