AMPS - Advanced Mobile Phone System


Chapter 3

[1]  Introduction
[2]  History of AMPS
[3]  Standards

Introduction

The current cellular phone system in the U.S. is known as AMPS (Advanced Mobile Phone Service). AMPS was designed in the mid-1960s; licenses were applied for in 1971 and finally granted in 1981. AMPS was rapidly deployed during the 1980s.

Demand for cellular service has far exceeded expectations: some 50 million people in the U.S. enjoy cellular phone service today and tens of thousands of people become subscribers each and every day. More than 20,000 base stations in the U.S. alone provide coverage to most of the population.

AMPS uses 50 MHz of spectrum in the 800 MHz band. The spectrum allocated to AMPS is shared by two cellular carriers in each area or region (that is, geographic market). Each carrier then divides the spectrum into forward channels, used to communicate from cell site base stations to mobile devices, and reverse channels, used for communications from mobile devices to cell site base stations. Channels are then divided into 30 kHz analog voice channels that employ frequency modulation (FM) technology to transmit voice.

Figure 1. System Interfaces