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DIFFERENT TYPESy Cellular Telephone Systems

y Cordless Phones

y Wireless LANS

y Wide Area Wireless Data Services

y Paging System

y Satellite Networks

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Cellular Telephone Syst em sy Also called Personal Communication Systems(PCS)

y Two-way Voice Communication

y Basic feature :Frequency Reuse

y Coverage Area Non-overlapping Cells set of channels

assigned

y O peration within a cell controlled byCentralized Base

Station

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Cellular Telephone Syst em sy Intercell Interference

y Interference caused by users in different cells operating on the same channel

y

Reuse Distancey Distance btw cells that use same channel

y Reuse Distance Decreases, Intercell Inference Increases

y M acrocells large cells

y M icrocells or Picocells smaller cells

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Cellular Telephone Syst em sy All Base Stations in a city connected toM obile Telephone

SwitchingO ffice(M TSO )

y M TWO

y Central controller

y Allocating channels

y Routing calls toPublic Switched Telephone Network(PSTN)

y Channel is available Accepts the call request

y No channel Call is rejected

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Cellular Telephone Syst em sy Analog Digital Technology

y Components

y

Cheaper, faster, smaller, less powery Voice quality improved E rror correction Code

y H igher Capacity

y Any multiple access technique can be usedy Interference - limited

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Cordle ss P hone sy Telephone + Radio

Transmitter

y Basey Handset

y E lectrical signals FM

Radio signals

y Broadcasts signal

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Wirele ss N e twork s Ca tegor ie sy Base Station all communication through anaccess point

O ther nodes can be fixed or mobile.

y I nfrastructure Wireless base station network is connected to

the wired Internet.

y A d hoc Wireless wireless nodes communicate directly with

one another.

y MANET s (M obile A d Hoc N etworks) ad hoc nodes are

mobile.

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Wirele ss LANs

(a)Wireless networking with a base station.(b) Ad hoc networking.

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Pag ing Syst em sy O ne way, personal wireless alerting/messaging system

y Types of Information delivered in a paging system:

y Alert Toney Voice M essage

y Digit String

y Text Strings

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Pag ing Ne twork Arch itec ture

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Sa tell ite Ne twork sy The two stations that arefar awaycan use a satellite as a

relay station for their communication

y O ne E arth Station sends a transmission to the satellite.This is called aUplink .

y The satelliteT ransponder converts the signal and

sends it down to the second earth station. This is called a

Downlink .

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Sa tell ite Ne twork sy Service Types

Fixed Service Satellites (FSS)E xample: Point to Point Communication

Broadcast Service Satellites (BSS)E xample: Satellite Television/Radio

Also called Direct Broadcast Service (DBS)

M obile Service Satellites (M SS)E xample: Satellite Phones

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Type s of Sa tell ite sy SatelliteO rbits

GeostationaryE arth O rbit (GEO )

Low E arth O rbit (LEO )

M edium E arth O rbit (MEO )

Molniya

Orbit

H igh Altitude Platform (H AP)

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