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Chapter 2:Introduction of Wireless and

Mobile Systems

Associate Prof. Yuh-Shyan Chen

Dept. of Computer Science and Information Engineering

National Chung-Cheng University

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In this course

We will discuss the design, deployment, and operation of mobile wireless systems.

The term cellular communications is often interchanged with the terms personal communication service (PCS), and the third-generation (3G) service

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Outline

CellularWLANBluetooth

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Cellular

One of most prolific voice communication platforms that has been deployed within the last two decades

Cellular systems have always been able to transport data, and many advancement in different modulation formats allow for the delivery of narrowband data.

Cellular systems are unable to provide broadband data service The bandwidth limitationsTypical data rate: 9 kilobits per second (Kbit/s)

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Generic Cellular System

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MSC

MSC (Mobile Switching Center)That in turn connects to the PSTN (Public

Switched Telephone Network) or postal, telegraph, and telephone (PTT) systems

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Their main usefulness in their capability to maintain the same contact number even if the user moves from one location to another

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Maintaining the telephone number in a wireless and mobile system

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Cellular

Cellular communication is the form of wireless that allows forFrequency reuseMobility of the subscriberHandoffs

Typically, the reference of cellular system is AMPS (Advanced Mobile Phone System) or TACS (Total-Access Communications System)

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First-Generation Wireless System and Service

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Cellular

AMPS operates in the 800 –MHz band821 to 849 MHz for the base station receive869 to 894 MHz for the base station transmitNorth America

TACS890 to 915 MHz for the base station receive935 to 960 MHz for the base station transmit

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Cellular

Many other technologiesSMR (Specialized Mobile Radio)IS-136 iDEN (Integrated Dispatch Enhanced Network)

Cellular radio was initially developed by AT&T (Bell Lab.)To provide additional radio capacity for a

geographic customer service area.

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Cellular

MTS (Mobile Telephone System) Initial mobile systmes

IMTS (Improved Mobile Telephone System)One of the main problem

A mobile call could not be transferred (handed off) from one radio station to another without loss of singnal

This problem was resolved by reusing the allocated frequencies of the system

With the handoff problem solved, the market was able to offer higher radio traffic capacityAllows for more users than with the MTS or IMTS

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Cellular

The cellular systems in USA are broken into MSAs (Metropolitan Statistical Areas)

A-band system

RSAs (Rural Statistical Areas)B-band system

The A band is nonwireline system, and B band is the wireline system for the MSA and RSA.

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Advanced mobile phone system (AMPS)

The cellular standard developed for use in North America

This type of system operates in the 800-MHz frequency

Also developed in South America, Asia, and Russia

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Nordic mobile telephone (NMT)

Developed by the Nordic countries of Sweden, Denmark, Finland, and Norway in 1981.

Operate in the 450- (NMT 450) and 900-MHz (NMT 900) frequency bands.

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Second-Generation Wireless System and Service

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Code-division multiple access (CDMA)

An alternative digital cellular standard in the United States

Utilizes the IS-95 standard and is implemented as the next generation for cellular systems.

The CDMA system coexists with the current analog system

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Digial AMPS (D-AMPS)

Also called North American Digital Cellular (NADC)

The D-AMPS is designed to coexist with current cellular systems

Relies on both the IS-54 and the IS-136 standards

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Global system for mobile communication (GSM)

The European standard for digital cellular systems operating in the 900-MHs band

This technology offers international roaming, high speed quality, increased security, and the ability to develop advanced system features

It was completed by a consortium of 80 pan-European countries working togetherTo provide integrated cellular systems across

different borders and cultures

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Total-access communications system (TACS)

Derived from AMPS technologyThe first system was implemented in

EnglandLater these systems were installed in

Europe, China, Hong Kong, Singapore, and the Middle East

A variation of this standard (JTACS) was implemented in Japan

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Integrated dispatch enhanced network (iDEN)

iDEN utilizes a digital radio format called quadrature amplitude modulation (QAM) and is a derivative of GSM

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Third-Generation Wireless System and Services

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Subscriber growth for wireless phones

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Coverage aspect of third-generation wireless communication systems

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Transmission Capacity

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Wireless Technologies and Associated Characteristics

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2.3 GHz

900 MHz

Modem

Wired Access Point

PoletopRadio

2.4 GHz

High-speed dedicated wired

connections

Internet and Corporate Networks

Network InterfaceFacility

The Ricochet Network Overview

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Easy Installation

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Nokia Rooftop Product

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WLAN

Wireless LAN (WLAN) WLAN protocol

IEEE 802.11BluetoothHiperLan/2

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WLAN

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802.11

802.11a, 802.11b (WiFi), and 802.11g802.11a operates in the 5-GHz

Unlicensed national information infrastructure (UNII) band

802.11b and 802.11g operates in the 2.4 GHz ISM band along with Bluetooth

See Table 1.2

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Comparisons between 802.11 and Bluetooth

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WLAN

The 802.11 specifications were designed initially as a wireless extension for a corporate LAN for enterprise applications

Numerous devices have been manufactured to this specificationThe 802.11b protocol is a shared medium and

utilizes a listen-before-talk protocol called collision sense multiple access/collision avoidance (CSMA/CA)

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WLAN

IEEE 802.11 is important for wireless mobility It provides direct mobile data interoperability

between LAN of a corporation and the wireless operator’s system

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HiperLan/2

Developed by European Telecommunication Standards Institute (ETSI)

Physical layer (similar with 802.11a) uses orthogonal frequency-division multiplexing (OFDM) and is developed in the 5-GHz band

Media-specific access control protocol (MAC) layer uses time-division multiple access (TDMA) format as compared to 802.11a which uses OFDM

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Wireless Network Models

With Infrastructure: Without Infrastructure (ad hoc networks):

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Illustration of an ad hoc network

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無線隨意網路（ Multi-hop Ad Hoc Network ）

Laptop

PDA

LaptopLaptop

Laptop

A

B

C

D

E

PDA

Laptop

Laptop

Laptop

PDA

PDA

C'

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A wireless sensor network

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感測網路（ Sensor Network ）

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Bluetooth Technology

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Bluetooth

Operates in the 2.4-GHz industrial-scientific medical (ISM) bandAllowing wireless connectivity between mobile

phones, PDAs, and other similar deviceIs meant to replace the infrared telemetry

portion on mobile phones and PDAsEnabling extended range and flexibility in

addition to enhanced service

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Bluetooth

Range is from 10 to 100 meters (m)The protocol does not require line of sight

(LOS) for establishing communicationThe pattern is omnidirectional Delivering data over radio For short distance

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Comparisons