Motorola M3097 Service Manual download pdf (Page 13)

©1999 Motorola, Inc.

TDMA M3090/M3097Cellular Overview

2

The cellular radio frequency spectrum has

been divided by the FCC into two equal seg-

ments or bands to allow two independent cel-

lular carriers to coexist and compete in the

same geographic coverage area. Each band

occupies one half of the available channels

in the cellular spectrum. Initially there were

666 channels available across the entire cel-

lular spectrum, but that number was ex-

panded to 832 channels in 1987, and with

NAMPS to 2,412 channels in 1991. Digital

cellular promises to make a further expan-

sion. To guarantee nationwide compatibil-

ity, the signaling channel frequencies have

been pre-assigned to each segment (band).

The two bands and their assigned channels

are defined in Figure 1.

Originally the B Band was assigned to the

telephone company (referred to by a euphe-

mism, the Wireline carrier). The A Band, by

default, was referred to as the Non-Wireline

carrier, guaranteed competition to the tele-

phone company. Today the terms Wireline

and Non-Wireline have little meaning since

telephone company carriers now operate A

Band systems, and vice-versa.

Control (Data) Channels

A cellular telephone in the cellular system is

under the indirect control of the switch, or

central controller. The central controller uses

dedicated control channels to provide the sig-

US Cellular Frequency Band

832 channels

001

1023

991 666

667

716

717

799

333

312

313

334

354

355

A' A' B'

Voice

Channels

Voice

Channels

Control

Channels

BB

A A

Band A Band B

A'

666

667

716

717

799

TDMA Secondary

Control Channels

737 - 757688 - 708

Figure 2. US Cellular Frequency Band

Introduction

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