Wireless Guide to Wireless Communications Chapter 10 Wireless

Wireless# Guide to Wireless Communications Chapter 10 Wireless Wide Area Networks Wireless# Guide to Wireless Communications

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 2

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 3

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 4

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 5

How Cellular Telephony Works (continued) Wireless# Guide to Wireless Communications 6

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 7

How Cellular Telephony Works (continued) Wireless# Guide to Wireless Communications 8

How Cellular Telephony Works (continued) Wireless# Guide to Wireless Communications 9

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 10

How Cellular Telephony Works (continued) Wireless# Guide to Wireless Communications 11

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 12

How Cellular Telephony Works (continued) Wireless# Guide to Wireless Communications 13

Digital Cellular Telephony • Cellular telephones have been available since the early 1980 s in the United States • Most industry experts outline several generations of cellular telephony Wireless# Guide to Wireless Communications 14

First Generation Cellular Telephony • First Generation (1 G) – 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 • 1 G networks use circuit-switching technology Wireless# Guide to Wireless Communications 15

First Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 16

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 17

Second Generation Cellular Telephony • Second Generation (2 G) – Transmits data between 9. 6 Kbps and 14. 4 Kbps • In the 800 MHz and 1. 9 GHz frequencies – 2 G networks are also circuit-switching – 2 G 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 18

Second Generation Cellular Telephony (continued) • Second Generation (2 G) (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 19

Second Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 20

Second Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 21

2. 5 Generation Cellular Telephony • 2. 5 Generation (2. 5 G) – – Interim step between 2 G and 3 G Operates at a maximum speed of 384 Kbps 2. 5 G 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 22

2. 5 Generation Cellular Telephony (continued) • 2. 5 G network technologies – General Packet Radio Service (GPRS) • For TDMA or GSM 2 G 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 – CDMA 2000 1 x. RTT • Operates on two 1. 25 MHz-wide frequency channels • Supports 144 Kbps packet data transmission Wireless# Guide to Wireless Communications 23

Third Generation Cellular Telephony • Third Generation (3 G) – 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 • 3 G network technologies – CDMA 2000 1 x. EVDO • For 2. 5 G CDMA 2000 1 x. RTT networks Wireless# Guide to Wireless Communications 24

Third Generation Cellular Telephony (continued) • 3 G network technologies (continued) – CDMA 2000 1 x. EVDV will be the successor of CDMA 2000 1 x. EVDO – Wideband CDMA (W-CDMA) • For 2. 5 G 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 25

Third Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 26

Third Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 27

Third Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 28

Third Generation Cellular Telephony (continued) Wireless# Guide to Wireless Communications 29

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 30

Wireless Application Protocol (WAP and WAP Version 2) • Wireless Application Protocol (WAP) and WAP 2 – 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 31

Wireless Application Protocol (WAP and WAP Version 2) (continued) Wireless# Guide to Wireless Communications 32

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 (W 3 C) – 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 33

Wireless Application Protocol (WAP and WAP Version 2) (continued) Wireless# Guide to Wireless Communications 34

Wireless Application Protocol (WAP and WAP Version 2) (continued) • WAP 2 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 – WAP 2 is backward compatible with WAP version 1 Wireless# Guide to Wireless Communications 35

i-Mode • i-mode – Internet access system – Owned by the Japanese corporation NTT Do. Co. Mo – Based on compact HTML (c. HTML) • A subset of HTML designed for mobile devices • c. HTML 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 36

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 (J 2 ME) – 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 37

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 38

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 39

Competing Technologies • There is no single road to 3 G digital telephony – Europe standards • W-CDMA and HSDPA – China and South Korea standards • CDMA 2000 1 x. EVDO – Japan standard • W-CDMA – United States standards • HSDPA and CDMA 2000 1 x. EVDO Wireless# Guide to Wireless Communications 40

Limited Spectrum • Spectrum – Single largest factor limiting the development of 3 G • Although 3 G can operate at almost any spectrum – Industry tries to use the same part of the spectrum for 3 G 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 41

Costs • High monthly service fees for data transmission • User cost for 3 G pales in comparison to costs for the carriers to build entire 3 G networks Wireless# Guide to Wireless Communications 42

Other Wireless Options • Top speed for a 3 G user is 10 Mbps downstream – 802. 11 g 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. 11 g – Factors that have kept this technology from being implemented in cellular phone handsets Wireless# Guide to Wireless Communications 43

Other Wireless Options (continued) • Impact of Wi. MAX – Two distinct kinds of WWAN set-up • 802. 16 -2004 and 802. 16 e – 802. 16 e Wi. MAX 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 -2004 Wi. MAX • Provides Internet and cable TV access to rural areas and remote cities Wireless# Guide to Wireless Communications 44

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 45

Satellite Broadband Wireless (continued) Wireless# Guide to Wireless Communications 46

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 47

Satellite Transmissions (continued) Wireless# Guide to Wireless Communications 48

Satellite Transmissions (continued) Wireless# Guide to Wireless Communications 49

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-tomultipoint Wireless# Guide to Wireless Communications 50

Satellite Transmissions (continued) Wireless# Guide to Wireless Communications 51

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 52

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 53

Low Earth Orbit (LEO) (continued) Wireless# Guide to Wireless Communications 54

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 55

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 56

Medium Earth Orbit (MEO) (continued) Wireless# Guide to Wireless Communications 57

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 58

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 59

Geosynchronous Earth Orbit (GEO) (continued) Wireless# Guide to Wireless Communications 60

Geosynchronous Earth Orbit (GEO) (continued) Wireless# Guide to Wireless Communications 61

Geosynchronous Earth Orbit (GEO) (continued) Wireless# Guide to Wireless Communications 62

Experimental Technologies • NASA has been experimenting with ultra-lightweight, solar-powered, high-flying aircraft since the 1990 s – To be used in place of a satellite or ground-based antenna tower infrastructure Wireless# Guide to Wireless Communications 63

Satellite Technology Outlook • Satellites can provide wireless communication – In areas not covered by cellular or Wi. MAX • 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 64

Summary • In cellular telephone networks, the coverage area is divided into sections called cells • Handoff vs. roaming • Cellular technology generations – – First generation (1 G) Second generation (2 G) 2. 5 generation (2. 5 G) Third generation (3 G) • Short Message Services (SMS) – Allows for the delivery of short, text-based messages Wireless# Guide to Wireless Communications 65

Summary (continued) • 2. 5 GWAP-enabled cell phones run a tiny browser program called a microbrowser • 3 G cell phones allow Internet surfing or videoconferencing using WAP 2 • Java 2 Micro Edition (J 2 ME) – 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 66

Summary (continued) • Introduction of Wi. MAX technologies – May have a significant impact on how 3 G 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 67