utilization is concerned, the conventional system does not utilize the spectrum efficiently
since each channel can only serve one customer at a time in a whole area. This is
overcomed by the new cellular system.
BASIC CELLULAR SYSTEMS
A basic analog cellular system consists of three subsystems: a mobile unit, a cell site,
and a mobile telephone switching office (MTSO), as Fig. 1.1 shows, with
connections to link the three subsystems.
1. Mobile units. A mobile telephone unit contains a control unit, a transceiver, and an
2. Cell site. The cell site provides interface between the MTSO and the mobile units.
It has a control unit, radio cabinets, antennas, a power plant, and data terminals.
3. MTSO. The switching office, the central coordinating element for all cell sites,
con-tains the cellular processor and cellular switch. It interfaces with telephone
company zone offices, controls call processing, provides operation and
maintenance, and han-dles billing activities.
4. Connections. The radio and high-speed data links connect the three subsystems.
Each mobile unit can only use one channel at a time for its communication link.
But the channel is not fixed; it can be any one in the entire band assigned by the
serving area, with each site having multichannel capabilities that can connect
simultaneously to many mobile units.
The MTSO is the heart of the analog cellular mobile system. Its processor provides
central coordination and cellular administration.
The cellular switch, which can be either analog or digital, switches calls to connect
mobile subscribers to other mobile subscribers and to the nationwide telephone
network. It uses voice trunks similar to telephone company interoffice voice trunks. It
also contains data links providing supervision links between the processor and the
switch and between the cell sites and the processor. The radio link carries the voice
and signaling between the mobile unit and the cell site. The high-speed data links