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Cellular Networking Perspectives
The AMPS Family of Wireless Standards
The AMPS family of wireless standards were designed in the 1970s to be just another analog radiotelephone 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, the ability to dial directly without operator intervention and its robust design, AMPS was a stunning success. At its peak in the early 1990s about half the cellular phones in the world operate according to AMPS standards, which, from 1988 were maintained and developed by the Telecommunications Industry Association (TIA). AMPS became the base from which the TDMA and CDMA digital technologies developed, building on many of the network protocols. TACS (or ETACS) and JTACS were close relatives, basically being AMPS in frequency bands other than 800MHz (e.g. 900MHz for TACS). The only other analog cellular system that has had anywhere near the success of the AMPS/TACS family is NMT (now being replaced in the 450 MHz band by CDMA).
Some of the major radio interface standards in the AMPS family are:
- EIA/TIA-553 Analog Cellular
- The ANSI version of the analog cellular standard. Generally one step behind IS-91, and without support for NAMPS. Currently Revision A is being published.
- EIA/TIA/IS-3 Analog Cellular
- The original analog cellular standard, now replaced by ANSI standard EIA/TIA-553 and TIA interim standard IS-91.
- TIA/EIA/IS-54 TDMA Digital Cellular
- A digital cellular system that squeezes three conversations into one cellular channel using Time Division Multiple Access technology. Also see TIA/EIA/IS-136.
- TIA/EIA/IS-88 Narrowband Analog Cellular
- A Motorola developed system that squeezes three conversations into one cellular channel using analog frequency division multiplexing (FDMA). First standardized in TIA interim standard IS-88, and now incorporated in IS-91.
- TIA/EIA/IS-91 Analog Cellular
- The TIA version of the analog cellular standard, incorporating the functionality of IS-88 (narrowband analog) and IS-94 and authentication.
- TIA/EIA/IS-94 In-building Cellular
- A standard for in-building operation of analog cellular systems using extremely low power. Now incorporated in IS-91. Never widely used.
- TIA/EIA-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. A new generation of CDMA standards, known as IS-2000 are now being developed.
- TIA/EIA-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 'analog' control channel, which although less sophisticated, is still digital!). The latest version being developed is ANSI standard TIA/EIA-136 Revision C.
IS-732 CDPD Packet Data
- A packet data system operating in a single AMPS channel. Reasonably popular, but now losing ground to systems based on GPRS or CDMA 1XRTT.
© Copyright Mon, May 14, 2007: Cellular Networking Perspectives Ltd.