Wireless guide to wireless communications
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Wireless# Guide to Wireless Communications. Chapter 10 Wireless Wide Area Networks. Objectives. Describe wireless wide area networks (WWANs) and how they are used Describe the applications that can be used on a digital cellular telephone Explain how cellular telephony functions

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Wireless guide to wireless communications

Wireless# Guide to Wireless Communications

Chapter 10

Wireless Wide Area Networks


Objectives

Objectives

  • Describe wireless wide area networks (WWANs) and how they are used

  • Describe the applications that can be used on a digital cellular telephone

  • Explain how cellular telephony functions

  • List features of the various generations of cellular telephony

  • Discuss how satellite transmissions work

Wireless# Guide to Wireless Communications


Cellular telephone applications

Cellular Telephone Applications

  • Digital cellular telephones can be used to:

    • Browse the Internet

    • Send and receive short messages and e-mails

    • Participate in videoconferencing

    • Receive various sorts of information

    • Run a variety of business applications

    • Connect to corporate networks

    • Watch television or on-demand movies

    • Take and transmit pictures and short movies

    • Locate family members and employees using GPS

Wireless# Guide to Wireless Communications


Cellular telephone applications continued

Cellular Telephone Applications (continued)

  • Short Message Services (SMS)

    • One of the most widely used applications

    • Allows for the delivery of short, text-based messages between wireless devices

      • Messages are limited to about 160 characters

    • Applications

      • Person-to-person

      • Agent-to-person

      • Information broadcast services

      • Software configuration

      • Advertising

Wireless# Guide to Wireless Communications


How cellular telephony works

How Cellular Telephony Works

  • Keys to cellular telephone networks

    • Cells

      • City cells measure approximately 10 square miles

      • At the center of each cell is a cell transmitter connected to a base station

      • Each base station is connected to a mobile telecommunications switching office (MTSO)

        • Link between the cellular network and the wired telephone world

        • Controls all transmitters and base stations

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

How Cellular Telephony Works (continued)

Wireless# Guide to Wireless Communications


How cellular telephony works continued

How Cellular Telephony Works (continued)

  • Keys to cellular telephone networks (continued)

    • Transmitters and cell phones operate at low power

      • Enables the signal to stay confined to the cell

      • Signal at a specific frequency does not go far beyond the cell area

        • Same frequency can be used in other cells at the same time

        • Except in adjacent cells

  • Cell phones have special codes

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

How Cellular Telephony Works (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

How Cellular Telephony Works (continued)

Wireless# Guide to Wireless Communications


How cellular telephony works continued1

How Cellular Telephony Works (continued)

  • When user moves within the same cell

    • Transmitter and base station for that cell handle all of the transmissions

  • As the user moves toward the next cell

    • A handoff process occurs

  • Roaming

    • User moves from one cellular network to another

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

How Cellular Telephony Works (continued)

Wireless# Guide to Wireless Communications


How cellular telephony works continued2

How Cellular Telephony Works (continued)

  • Steps to receive a call

    • Cell phone listens for the SID being transmitted by the base station on the control channel

    • Phone compares SID with its programmed SID

      • If they match, phone is in a network owned by carrier

    • If SIDs do not match, phone is roaming

    • When a call comes in, MTSO locates the phone through the registration request

    • User can move to another cell

    • Phone and transmitter can change frequencies

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

How Cellular Telephony Works (continued)

Wireless# Guide to Wireless Communications


Digital cellular telephony

Digital Cellular Telephony

  • Cellular telephones have been available since the early 1980s in the United States

  • Most industry experts outline several generations of cellular telephony

Wireless# Guide to Wireless Communications


First generation cellular telephony

First Generation Cellular Telephony

  • First Generation (1G)

    • Uses analog signals modulated using FM

    • Based on Advanced Mobile Phone Service (AMPS)

      • Operates in the 800-900 MHz frequency spectrum

      • Each channel is 30 KHz wide with a 45 KHz passband

      • There are 832 frequencies available

      • Uses Frequency Division Multiple Access (FDMA)

      • FDMA allocates a single cellular channel with two frequencies to one user at a time

  • 1G networks use circuit-switching technology

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

First Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


First generation cellular telephony continued

First Generation Cellular Telephony (continued)

  • Circuit-switching technology

    • Makes a dedicated and direct physical connection

      • Between the caller and the recipient

  • Analog signals are prone to interference

    • Do not have the same quality as digital signals

Wireless# Guide to Wireless Communications


Second generation cellular telephony

Second Generation Cellular Telephony

  • Second Generation (2G)

    • Transmits data between 9.6 Kbps and 14.4 Kbps

      • In the 800 MHz and 1.9 GHz frequencies

    • 2G networks are also circuit-switching

    • 2G systems use digital transmissions

    • Digital transmission benefits

      • Uses the frequency spectrum more efficiently

      • Over long distances, the quality of the voice transmission does not degrade

      • Difficult to decode and offer better security

Wireless# Guide to Wireless Communications


Second generation cellular telephony continued

Second Generation Cellular Telephony (continued)

  • Second Generation (2G) (continued)

    • Digital transmission benefits (continued)

      • Digital transmissions use less transmitter power

      • Enables smaller and less expensive individual receivers and transmitters

  • Multiple access technologies

    • Time Division Multiple Access (TDMA)

    • CDMA

    • Global System for Mobile communications (GSM)

      • Uses a combination of FDMA and TDMA technologies

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Second Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Second Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


2 5 generation cellular telephony

2.5 Generation Cellular Telephony

  • 2.5 Generation (2.5G)

    • Interim step between 2G and 3G

    • Operates at a maximum speed of 384 Kbps

    • 2.5G networks are packet-switched

    • Advantages of packet switching

      • Much more efficient

        • Can handle more transmissions over a given channel

      • Permits an always-on connection

Wireless# Guide to Wireless Communications


2 5 generation cellular telephony continued

2.5 Generation Cellular Telephony (continued)

  • 2.5G network technologies

    • General Packet Radio Service (GPRS)

      • For TDMA or GSM 2G networks

      • Uses eight time slots in a 200 KHz spectrum and four different coding techniques

    • Enhanced Data rates for GSM Evolution (EDGE)

      • Can transmit up to 384 Kbps

      • Based on a modulation technique called 8-PSK

    • CDMA2000 1xRTT

      • Operates on two 1.25 MHz-wide frequency channels

      • Supports 144 Kbps packet data transmission

Wireless# Guide to Wireless Communications


Third generation cellular telephony

Third Generation Cellular Telephony

  • Third Generation (3G)

    • Intended to be a uniform and global standard for cellular wireless communication

  • Standard data rates

    • 144 Kbps for a mobile user

    • 386 Kbps for a slowly moving user

    • 2 Mbps for a stationary user

  • 3G network technologies

    • CDMA2000 1xEVDO

      • For 2.5G CDMA2000 1xRTT networks

Wireless# Guide to Wireless Communications


Third generation cellular telephony continued

Third Generation Cellular Telephony (continued)

  • 3G network technologies (continued)

    • CDMA2000 1xEVDV will be the successor of CDMA2000 1xEVDO

    • Wideband CDMA (W-CDMA)

      • For 2.5G EDGE networks

    • High-Speed Downlink Packet Access (HSDPA)

      • Beyond W-CDMA

      • Uses a 5 MHz W-CDMA channel, variety of adaptive modulation, multiple in multiple out (MIMO) antennas, and hybrid automatic repeat request (HARQ)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Third Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Third Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Third Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Third Generation Cellular Telephony (continued)

Wireless# Guide to Wireless Communications


Client software

Client Software

  • Internet surfing or videoconferencing require client software

    • To operate on a wireless digital cellular device

  • Common types of clients

    • WAP

    • i-mode

    • Java

    • BREW

Wireless# Guide to Wireless Communications


Wireless application protocol wap and wap version 2

Wireless Application Protocol (WAP and WAP Version 2)

  • Wireless Application Protocol (WAP) and WAP2

    • Provide a standard way to transmit, format, and display Internet data

      • For devices such as cell phones

  • WAP was developed in 1997

    • Enables devices to send and receive Internet text-only data

  • WAP cell phone runs a microbrowser

    • Uses Wireless Markup Language (WML) instead of HTML

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Wireless Application Protocol (WAP and WAP Version 2) (continued)

Wireless# Guide to Wireless Communications


Wireless application protocol wap and wap version 2 continued

Wireless Application Protocol (WAP and WAP Version 2) (continued)

  • WAP gateway (sometimes called WAP proxy)

    • Computer running special conversion software

    • Used to translate between WML and HTML

    • Many features of HTML are not supported in WML

  • Extensible Markup Language (XML)

    • Defined by the World Wide Web Consortium (W3C)

    • Uses tags to describe how an item should be displayed on the screen

  • WML document is called a deck

    • Contains one or more blocks, known as cards

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Wireless Application Protocol (WAP and WAP Version 2) (continued)

Wireless# Guide to Wireless Communications


Wireless application protocol wap and wap version 2 continued1

Wireless Application Protocol (WAP and WAP Version 2) (continued)

  • WAP2 is based on XHTML (an extension of HTML version 4)

    • Displays graphics and multiple font styles on color screen equipped mobile devices

    • Includes a protocol stack that allows it to support TCP/IP directly

    • Defines a new profile, an extension of XML, specifically to support mobile devices

    • WAP2 is backward compatible with WAP version 1

Wireless# Guide to Wireless Communications


I mode

i-Mode

  • i-mode

    • Internet access system

    • Owned by the Japanese corporation NTT DoCoMo

    • Based on compact HTML(cHTML)

      • A subset of HTML designed for mobile devices

      • cHTML has its own set of tags and attributes

  • i-mode users pay for the service

    • By the amount of information downloaded plus a service charge

  • WAP services are charged by the connection time

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Java

  • Java programming language

    • Developed by Sun Microsystems

    • Object-oriented language used for general-purpose business programming

      • As well as interactive Web sites

  • Java 2 Micro Edition (J2ME)

    • Subset of Java specifically developed for programming wireless devices

    • Enables a cellular phone to access remote applications and e-mail

      • As well as run programs on the cellular phone itself

Wireless# Guide to Wireless Communications


Binary runtime environment for wireless brew

Binary Runtime Environment for Wireless (BREW)

  • BREW is a thin software environment

    • Very small program that resides on a wireless device

      • Capable of running applications that can be downloaded by the device on demand

    • BREW is compatible with Java, C, and C++

  • BREW efficiently uses small amount of memory

    • Occupies only a small amount of flash memory

    • Dynamically allocates RAM for applications

  • BREW can be used with other applications

Wireless# Guide to Wireless Communications


Digital cellular challenges and outlook

Digital Cellular Challenges and Outlook

  • Users will benefit the most from digital cellular telephony

    • Once the industry settles on a single cellular standard

Wireless# Guide to Wireless Communications


Competing technologies

Competing Technologies

  • There is no single road to 3G digital telephony

    • Europe standards

      • W-CDMA and HSDPA

    • China and South Korea standards

      • CDMA2000 1xEVDO

    • Japan standard

      • W-CDMA

    • United States standards

      • HSDPA and CDMA2000 1xEVDO

Wireless# Guide to Wireless Communications


Limited spectrum

Limited Spectrum

  • Spectrum

    • Single largest factor limiting the development of 3G

  • Although 3G can operate at almost any spectrum

    • Industry tries to use the same part of the spectrum for 3G communications around the world

      • 1.710 to 1.855 GHz and 2.520 to 2.670 GHz

  • U.S. Department of Defense currently uses the 1.7 GHz band for satellite control and military purposes

Wireless# Guide to Wireless Communications


Costs

Costs

  • High monthly service fees for data transmission

  • User cost for 3G pales in comparison to costs for the carriers to build entire 3G networks

Wireless# Guide to Wireless Communications


Other wireless options

Other Wireless Options

  • Top speed for a 3G user is 10 Mbps downstream

    • 802.11g WLANs offer speeds of over 54 Mbps

  • Coverage area of a single WLAN is far less than a digital cellular network

    • Deploying multiple access points can create large areas of coverage

  • Higher power consumption and the large number of electronic components of 802.11g

    • Factors that have kept this technology from being implemented in cellular phone handsets

Wireless# Guide to Wireless Communications


Other wireless options continued

Other Wireless Options (continued)

  • Impact of WiMAX

    • Two distinct kinds of WWAN set-up

      • 802.16-2004 and 802.16e

    • 802.16e WiMAX network can be overlaid on an existing cellular tower infrastructure

      • Provides mobile users with lower cost access to data at speeds equivalent to EVDO

    • 802.16-2004WiMAX

      • Provides Internet and cable TV access to rural areas and remote cities

Wireless# Guide to Wireless Communications


Satellite broadband wireless

Satellite Broadband Wireless

  • Use of satellites for personal wireless communication is fairly recent

  • Satellite use falls into three broad categories

    • Satellites are used to acquire scientific data and perform research in space

    • Satellites look at Earth from space

    • Satellites include devices that are simply reflectors

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Satellite Broadband Wireless (continued)

Wireless# Guide to Wireless Communications


Satellite transmissions

Satellite Transmissions

  • Satellites generally send and receive on one of four frequency bands

  • Frequency band affects the size of the antenna

Wireless# Guide to Wireless Communications


Satellite transmissions continued

Satellite Transmissions (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Satellite Transmissions (continued)

Wireless# Guide to Wireless Communications


Satellite transmissions continued1

Satellite Transmissions (continued)

  • Class and Type of Service

    • Satellites can provide two classes of service

      • Consumer class service

        • Shares the available bandwidth between the users

      • Business class service

        • Offers dedicated channels with dedicated bandwidth

    • Types of connectivity

      • Point-to-point, point-to-multipoint, and multipoint-to-multipoint

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Satellite Transmissions (continued)

Wireless# Guide to Wireless Communications


Satellite transmissions continued2

Satellite Transmissions (continued)

  • Modulation techniques

    • Binary phase shift keying (BPSK)

    • Quadrature phase shift keying (QPSK)

    • Eight-phase shift keying (8-PSK)

    • Quadrature amplitude modulation (QAM)

  • Multiplexing techniques

    • Permanently assigned multiple access (PAMA)

    • Multi-channel per carrier (MCPC)

    • Demand assigned multiple access (DAMA)

Wireless# Guide to Wireless Communications


Low earth orbit leo

Low Earth Orbit (LEO)

  • Low earth orbit (LEO) satellites

    • Circle the Earth at an altitude of 200 to 900 miles

    • Must travel at high speeds

      • So that the Earth’s gravity will not pull them back into the atmosphere

    • Area of Earth coverage (called the footprint) is small

  • LEO systems have a low latency

    • Use low-powered terrestrial devices (RF transmitters)

    • Round trip time: 20 to 40 milliseconds

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Low Earth Orbit (LEO) (continued)

Wireless# Guide to Wireless Communications


Low earth orbit leo continued

Low Earth Orbit (LEO) (continued)

  • LEO satellites groups

    • Big LEO

      • Carries voice and data broadband services, such as wireless Internet access

    • Little LEO

      • Provides pager, satellite telephone, and location services

Wireless# Guide to Wireless Communications


Medium earth orbit meo

Medium Earth Orbit (MEO)

  • Medium earth orbit (MEO) satellites

    • Orbit the Earth at altitudes between 1,500 and 10,000 miles

    • Some MEO satellites orbit in near-perfect circles

      • Have a constant altitude and constant speed

    • Other MEO satellites revolve in elongated orbits called highly elliptical orbits (HEOs)

  • Advantages

    • MEO can circle the Earth in up to 12 hours

    • Have a bigger Earth footprint

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Medium Earth Orbit (MEO) (continued)

Wireless# Guide to Wireless Communications


Medium earth orbit meo continued

Medium Earth Orbit (MEO) (continued)

  • Disadvantage

    • Higher orbit increases the latency

    • Round trip time: 50 to 150 milliseconds

  • HEO satellites

    • Have a high apogee (maximum altitude) and a low perigee (minimum altitude)

    • Can provide good coverage in extreme latitudes

    • Orbits typically have a 24-hour period

Wireless# Guide to Wireless Communications


Geosynchronous earth orbit geo

Geosynchronous Earth Orbit (GEO)

  • Geosynchronous earth orbit (GEO) satellites

    • Stationed at an altitude of 22,282 miles

    • Orbit matches the rotation of the Earth

      • And moves as the Earth moves

    • Can provide continuous service to a very large footprint

      • Three GEO satellites are needed to cover the Earth

    • Have high latencies of about 250 milliseconds

    • Require high-powered terrestrial sending devices

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Geosynchronous Earth Orbit (GEO) (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Geosynchronous Earth Orbit (GEO) (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Geosynchronous Earth Orbit (GEO) (continued)

Wireless# Guide to Wireless Communications


Experimental technologies

Experimental Technologies

  • NASA has been experimenting with ultra-lightweight, solar-powered, high-flying aircraft since the 1990s

    • To be used in place of a satellite or ground-based antenna tower infrastructure

Wireless# Guide to Wireless Communications


Satellite technology outlook

Satellite Technology Outlook

  • Satellites can provide wireless communication

    • In areas not covered by cellular or WiMAX

  • Satellites today are enabling carriers to offer

    • Internet access and voice calls to passengers and crews across large oceans

      • And in high latitudes and remote corners of the Earth

  • Can also make these services available in many other unpopulated areas

Wireless# Guide to Wireless Communications


Summary

Summary

  • In cellular telephone networks, the coverage area is divided into sections called cells

  • Handoff vs. roaming

  • Cellular technology generations

    • First generation (1G)

    • Second generation (2G)

    • 2.5 generation (2.5G)

    • Third generation (3G)

  • Short Message Services (SMS)

    • Allows for the delivery of short, text-based messages

Wireless# Guide to Wireless Communications


Summary continued

Summary (continued)

  • 2.5GWAP-enabled cell phones run a tiny browser program called a microbrowser

  • 3G cell phones allow Internet surfing or videoconferencing using WAP2

  • Java 2 Micro Edition (J2ME)

    • Subset of Java specifically developed for programming wireless devices

  • BREW is a runtime environment that resides on a wireless device

  • Issues preventing digital cellular acceptance include

    • Competing cellular technologies and lack of standards

Wireless# Guide to Wireless Communications


Summary continued1

Summary (continued)

  • Introduction of WiMAX technologies

    • May have a significant impact on how 3G technologies are eventually employed

  • Satellites used for wireless data connectivity

    • Employ common modulation and multiplexing techniques

  • Satellite orbit types

    • LEO satellites

    • MEO satellites

    • GEO satellites

Wireless# Guide to Wireless Communications


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