Wireless Mobile Networking with ANSI-41, Second Edition.pdf

Source: Wireless Mobile Networking with ANSI-41

PART

Introduction

to Wireless

Telecommunications,

Network

Architecture, and

Functions

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Introduction to Wireless Telecommunications, Network Architecture, and Functions

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)

Any use is subject to the Terms of Use as given at the website.

Source: Wireless Mobile Networking with ANSI-41

CHAPTER

Basics of

Wireless

Telecommunications

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Basics of Wireless Telecommunications

Part 1: Introduction to Wireless Telecommunications

To begin to understand the ANSI-41 signaling protocol, it is necessary to

understand some basics about wireless telecommunications. This chap-

ter provides a general overview of the most important concepts in wire-

less cellular telecommunications that apply to ANSI-41. For some read-

ers, this will be a high-level review; for others, it may clarify some

misconceptions and provide an overall understanding of cellular wire-

less technology that will be useful in understanding ANSI-41.

What Are Wireless

Telecommunications?

The concept of wireless telecommunications can be viewed from two per-

spectives: the wireless subscriber’s and the wireless network’s. From the

subscriber’s perspective, wireless telecommunications is a service that

allows telephone calls to be made or received while the telephone equip-

ment moved from place to place or while it is in motion. From this per-

spective, the telephone handset (known as the mobile station ) is wireless

and affords the ability to be mobile.

From the network’s perspective, wireless telecommunications is a

service provided to end-users. Wireless telecommunications, within the

context of ANSI-41, is a service based on a set of functions internal to

the network known as mobility management . Mobility management

functions enable the network to maintain location and subscriber status

information so that end-users can make and receive calls while they

move from place to place.

Origin of Advanced

Mobile Phone System

Wireless telecommunications can be considered both a system and a

service. The network equipment including antennas, radios, switches,

databases, and all hardware and software within the network, repre-

sents a wireless telecommunications system that provides wireless

telecommunications service to subscribers.

The first wireless telecommunications system based on cellular tech-

nology was (and is) known as AMPS (Advanced Mobile Phone System), a

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Basics of Wireless Telecommunications

Chapter 1: Basics of Wireless Telecommunications

technology developed by Bell Laboratories in 1947. The term cellular

refers to a network of small cells or radio transceivers, each providing a

limited range of radio coverage, which are linked by a computer-con-

trolled switching system that manages subscriber mobility and interfaces

to the fixed wire-line telephone network. The technology is based on cel-

lular frequency reuse (described later), providing a high-capacity system

and allowing network access using low-power mobile stations (typically

less than 6 W). The radio transceiver modulation methods used are based

on analog frequency modulation (FM) signals similar to those used for

commercial radio, but at a higher frequency range and lower bandwidth.

The first commercial cellular system in the United States became

operational in Chicago in 1983. However, other countries around the

world provided operational cellular systems several years earlier.

Today, cellular systems based on AMPS technology are implemented

in more than 100 countries. It is interesting to note, however, that there

is no single worldwide standard for the implementation of these cellular

systems. The different systems deployed generally represent differing

radio technologies, each based on the concepts of AMPS. The networking

technologies used to link the cells together are also quite different.

These technologies are considered supplemental to the defining charac-

teristics of AMPS (i.e., cells, frequency reuse, etc.). In fact, AMPS can

operate within a variety of networking schemes.

Some Basic Cellular Concepts

Basic Radio Technology

Cellular radio technology allows a subscriber to originate and receive

telephone calls wherever compatible cellular radio coverage is provided.

A cell is an individual radio coverage area controlled by a radio base sta-

tion (BS) system. Individual calls within a single cell use different fre-

quencies. These frequencies can be reused by other cells, provided that

there is no interference with the other cells. The frequency reuse pat-

tern of the cells is dependent on the distance between the cells and the

radio transmission power.

First-generation radio technologies (AMPS-based) use signals based

on analog FM for speech transmission. Subsequent generations of radio

technology for wireless systems include NAMPS (narrowband AMPS),

which is also based on analog FM, and a variety of sophisticated digital

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Any use is subject to the Terms of Use as given at the website.

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