General 1G System Architecture

A generic 1G cellular system configuration is shown in Figure 2-1. The configuration
involves all the high-level system blocks of a cellular network.
Many components comprise each of the blocks shown in Figure 2-1. The
individual system components of a cellular network will be covered in later
chapters of this book.
Referring to Figure 2-1, the mobile communicates to the cell site through
the use of radio transmissions. The radio transmissions utilize a full-duplex
configuration, which involves separate transmit and receive frequencies
used by the mobile and cell sites. The cell site transmits on the frequency
that the mobile unit is tuned to, while the mobile unit transmits on the
radio frequency the cell site receiver is tuned to.
The cell site acts as a conduit for the information transfer converting the
radio energy into another medium. The cell site sends and receives information
from the mobile and the mobile telephone system office (MTSO).The
MTSO is connected to the cell site either by leased T1/E1 lines or through
a microwave system. The cellular system is made up of many cell sites that
all interconnect back to the MTSO.

The MTSO processes the call and connects the cell site radio link to the
Public Service Telephone Network (PSTN). The MTSO performs a variety of
functions involved with call processing and is effectively the brains of the
network. The MTSO maintains the individual subscriber records, the current
status of the subscribers, call routing, and billing information to mention
a few items.