The code division multiple access (CDMA) system is a 2nd generation digital mobile radio communication system that provides for voice and medium-speed data communication services. Upgrading to CDMA capability from 1st generation analog mobile ystems allows CDMA service providers to add more customers for each radio tower (cell site), offer medium-speed data communication services, and to provide new high-value information services.

The CDMA system is composed of mobile devices (wireless telephones and data communication devices), radio towers (cell sites), and an interconnection system (switches and data routers). The IS-95 CDMA system (a specific standard for CDMA) uses three key types of radio channels; a wideband digital channel, a narrowband analog voice channel, and a narrowband analog control channel. The wideband digital radio channel provides for both multiple voice (audio) channels and control channels. The narrowband analog voice (audio) channels and analog control channel are slightly modified versions of the advanced mobile phone service (AMPS) radio channels.

There are three types of mobile devices that can operate on an IS-95 CDMA system; CDMA digital only; CDMA digital and AMPS analog, and AMPS analog only. The decision to include both analog and digital channels into the IS-95 CDMA system allowed for a gradual migration of AMPS analog customers to advanced digital services.

CDMA radio towers (cell sites) are composed of each the antenna system and radio equipment (base station). CDMA base stations contain one or more CDMA digital and/or AMPS analog radio channels. The base station converts radio signals from mobile devices...