Introduction to EVDO: Physical Channels, Logical Channels, Network and Operation

Access points (called base stations) may be stand alone transmission systems or part of a cell site and is composed of an antenna system (typically a radio tower), building, and base station radio equipment. Base station radio equipment consists of RF equipment (transceivers and antenna interface equipment), controllers, and power supplies. Access point transceivers have many of the same basic parts as a mobile device. However, access point radios are coordinated by the EVDO system's BSC and have many additional functions than a mobile device.
The radio transceiver section is divided into transmitter and receiver assemblies. The transmitter section converts a voice signal to RF for transmission to wireless devices and the receiver section converts RF from the wireless device to voice signals routed to the MSC or packet switching network. The controller section commands insertion and extraction of signaling information.
Unlike wireless devices (such as a mobile telephone or laptop computer), the transmitter, receiver, and control sections of an access point may be grouped into equipment racks. For example, a single equipment rack may contain all of the RF amplifiers or voice channel cards. Unlike analog or early-version digital cellular systems that dedicated one transceiver in each base station for a control channel, the EVDO system combines control channels and voice channels are mixed on a single physical radio channel.
Wireless base station antenna heights can vary from a few feet to more than three hundred feet. Radio towers raise the height...