Wireless A to Z pdf

Advanced Mobile Phone Service 6Air-Ground Radiotelephone Service 8 Amateur Radio Service 12 Cellular Voice Communications 48 Citizens Band Radio Service 55 Code Division Multiple Access

A to Z

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To my brother Jim

On his retirement from the South Burlington, Vermont,

Police Department

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Advanced Mobile Phone Service 6

Air-Ground Radiotelephone Service 8

Amateur Radio Service 12

Cellular Voice Communications 48

Citizens Band Radio Service 55

Code Division Multiple Access 59

Competitive Local Exchange Carriers 67

Cordless Telecommunications 70

Data Compression 75

Decibel 80

Digitally Enhanced Cordless Telecommunications 82

Direct Broadcast Satellite 87

Enhanced Data Rates for Global Evolution 95

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viii CONTENTS

Family Radio Service 97

Federal Communications Commission 99

Fixed Wireless Access 103

Fraud Management Systems 105

Frequency Division Multiple Access 119

Global Maritime Distress and Safety System 123

General Mobile Radio Service 125

General Packet Radio Service 128

Global Positioning System 131

Global System for Mobile (GSM) Telecommunications 139

Local Multipoint Distribution Service 198

Low-Power FM Radio Service 205

Low-Power Radio Service 208

Maritime Mobile Service 211

Microwave Communications 213

Mobile Telephone Switching Office 217

Multichannel Multipoint Distribution Service 220

Multichannel Video Distribution and Data Service 223

Over-the-Air Service Activation 225

Personal Access Communications Systems 251

Personal Air Communications Technology 254

Personal Communications Services 262

Personal Digital Assistants 266

Personal Handyphone System 273

Private Land Mobile Radio Services 279

x CONTENTS

Wireless Application Protocol 394

Wireless Application Service Providers 401

Wireless Centrex 405

Wireless Communications Services 409

Wireless Fidelity 411

Wireless Internet Access 414

Wireless Internet Service Providers 422

Wireless Local Loops 454

Wireless Local Number Portability 464

Wireless Management Tools 465

Wireless Medical Telemetry Service 468

Wireless Messaging 470

Wireless PBX 473

Wireless Telecommunications Bureau 481

Wireless Telecommunications Investment Fraud 483

Acronyms 487

Index 519

Of all the communications services available today, wirelessservices are having the most dramatic impact on our personaland professional lives, enhancing personal productivity,mobility, and security With every new wireless product andservice, the boundary between home and office is blurredfurther, perhaps to the point that one day they will be indis-tinguishable Instead of the flexible work schedule, wirelessproducts and services give us the capability of being “alwayson.” For a growing number of people, a true vacation consists

of shutting down communication with the rest of the world.The wireless industry worldwide is experiencing rapidinnovation, increased competition, and diversity in serviceofferings—all of which have resulted in lower prices for con-sumers and businesses Service providers continue to fill ingaps in their national coverage through mergers, acquisi-tions, license swaps, and joint ventures Along with thisprocess of footprint building, service providers continue todeploy their networks in an increasing number of markets,expand their digital networks, and develop pricing plans thatattract new subscribers and stimulate minutes of usage Mobile telephony is a particularly vibrant sector, experi-encing strong growth and reaching new levels of competitivedevelopment At year-end 2001, mobile telephony servicesgenerated over $65 billion in revenues in the United States,increased subscribers from 109.5 million to 128.5 million, andproduced a nationwide penetration rate of over 50 percent.Broadband PCS carriers and digital SMR providers con-tinue to deploy their networks According to the FederalCommunications Commission (FCC), 268 million people, or

94 percent of the total U.S population, live in areas served

xi

xii PREFACE

by three or more different operators offering mobile telephoneservice Over 229 million people, or 80 percent of the U.S.population, live in counties with five or more mobile tele-phone operators competing to offer service And 151 millionpeople, or 53 percent of the population, live in areas in whichsix different mobile telephone operators are providing service Digital technology is now dominant in the mobile tele-phone sector At the end of 2001, digital customers made upalmost 80 percent of the industry total, up from 72 percent

at year-end 2000 In part because of competitive pressures

in the marketplace, the average price of residential mobiletelephone service declined by 5.5 percent during 2001 Theaverage revenue per minute of mobile telephone use fell 31percent between 2000 and 2001

Many mobile telephone carriers are deploying advancedwireless service network technologies such as cdma20001xRTT and General Packet Radio Service (GPRS) Thesedeployments have contributed to the further convergence ofmobile voice and data The increased capacity on these digitalnetworks has permitted operators to offer calling plans withlarge buckets of relatively inexpensive minutes, free enhancedservices such as voice mail and caller ID, and wireless dataand mobile Internet offerings

Once solely a business tool, wireless phones are now amass-market consumer device By some estimates, 3 to 5percent of customers use their wireless phones as their onlyphone Though relatively few wireless customers have “cutthe cord” in the sense of canceling their wireline telephoneservice, there is growing evidence that consumers are sub-stituting wireless service for traditional phone service It isalso estimated that 20 percent of residential customers havereplaced some wireline phone usage with wireless, and that

11 percent have replaced a significant percentage Andalmost one in five mobile telephony users regard their wire-less phone as their primary phone

Contributing to these trends is the increasing number ofmobile wireless carriers offering service plans designed tocompete directly with wireline local telephone service, many

PREFACE xiii

with virtually unlimited regional calling plans For $40 to

$50 per month, subscribers get a calling plan that includes4,000 minutes (usable anytime) and the ability to roamacross several states without extra fees

Several local carriers have attributed declining access-linegrowth rates in part to substitution by wireless The number

of residential access lines served by BellSouth, SBC, andVerizon dropped by almost 3 percent during 2001, or morethan 2.5 million lines Verizon attributes the decline in thenumber of access lines in part to the shift to wireless phones.Nationwide, by year-end 2001, wireless had displaced anestimated 10 million access lines, primarily by consumerschoosing wireless over installing additional access lines.Wireless plans are substituting for traditional wirelinelong distance as well Many calling plans offered by nationalwireless carriers include free nationwide long distance Forexample, about 20 percent of AT&T’s customers, or 5 millionpeople, have replaced some wireline long-distance usage withwireless AT&T attributes the decline in its long-distancecalling volumes and revenues in part to wireless substitution

At least one wireless operator, Cingular Wireless, advertisesits nationwide calling plans with the slogan, “Never PayLong Distance Again.”

Because of national advertising and the Internet, sumers all over the country are educated about nationwiderate plans and services enabled by digital technology andthe prices of wireless handsets No matter where they live,customers expect and demand the diversity of services atcompetitive rates

con-Wireless is having an impact in other ways PDAs, orhandheld devices, began as electronic organizers containingpersonal information management (PIM) functions, such

as an address book, calendar, and to-do list that could be

“synched” with PIM software on a user’s desktop computer.While PDAs still contain these core PIM and software fea-tures, handhelds are being repositioned as wireless commu-nication devices instead of simple organizers All of the PDAmodels introduced by the major manufacturers since 2001

xiv PREFACE

allow users some method of connecting to the Internet lessly Some combine the features of mobile phones and PDAfeatures into so-called “smartphones.”

wire-Compared to traditional mobile handsets, smartphonesgenerally have larger screens, more advanced graphics andprocessing capabilities, more memory, a more user-friendlyoperating system, some form of keypad, and the ability tosynch data with and download software from a desktopcomputer Smartphones also integrate traditional mobiletelephone phone number storage and access with a PDA’saddress book so users are not required to store numbers intwo different places

These smartphones also allow messaging via the ShortMessage Service (SMS) SMS provides the ability for users tosend and receive text messages to and from mobile handsetswith maximum message length ranging from 120 to 500characters SMS also can be used to deliver a wide range ofinformation to mobile users, including stock prices, sportscores, news headlines, weather reports, and horoscopes.Worldwide, SMS has become increasingly popular, growing

to 250 billion messages sent over wireless networks wide in 2001

world-Using their existing and next-generation networks, majormobile telephone service providers offer text-based wirelessweb services via mobile telephone handsets at speeds rangingfrom approximately 14.4 kbps on 2G networks to 60 kbps onadvanced 2.5/3G wireless networks During 2001, mobiletelephone providers expanded their data service offerings asthey began to transition their networks to higher speedtechnologies In addition to offering wireless web service onmobile telephone handsets, several carriers offer wirelessInternet connections via wireless modem cards for PDAs andlaptop computers as well

Mobile telephone service providers offer wireless webservices that enable customers to surf web sites for news,stock quotes, traffic reports, weather forecasts, movie listings,shopping, and other text-based information To deliver wire-less web content to wireless handset users, carriers currently

PREFACE xv

restrict users to less graphically enriched content This serves the resources of the memory-constrained devices.However, customers who connect to the Internet via a wire-less modem card attached to a notebook computer are able toaccess the full content of the web

Many PDAs have the ability to access almost the entire tent of the web For example, Pocket PC PDAs include a PDAversion of Microsoft’s Internet Explorer web browser, whichcan access any web site While many PDAs have the potential

con-to access web content with their browsing software, they stillrequire a subscription to a wireless Internet Service Provider(WISP) in order to connect to the Internet via wireless links

As workers become increasingly more mobile and remote,the ability for employees outside the office to access e-mailmessages and files stored electronically on corporate servers

is likely to become an increasingly more important mobiledata application Analysts claim that giving employeesmobile access to e-mail and to data and applications stored

on corporate servers are two of the most important uses ofPDAs in the enterprise market Surveys of U.S firms indicatethat mobile access to e-mail is the top priority

There are short-range data transmission technologies thatare gaining in popularity: infrared, Bluetooth, and WirelessFidelity (Wi-Fi) Infrared is currently used in some PDAs toallow users to transfer data between two devices Infrared isalso the technology commonly used in remote controls andrequires line-of-sight transmission Bluetooth enables multi-point broadcasting applications, and Wi-Fi enables devices toconnect to wireless local area networks (WLANs)

Bluetooth is a technology used to establish wireless nectivity between electronic devices that are up to 30 ft (10 m)apart It allows users to send signals and transfer dataamong numerous electronic devices, thus creating a personalarea network (PAN) Bluetooth uses unlicensed spectrum

con-in the 2.4 GHz band and transmits data at speeds close to

1 Mbps Bluetooth also uses frequency hopping spread trum techniques to provide enhanced communications per-formance and an initial level of transmission security

spec-xvi PREFACE

Wi-Fi is another wireless networking technology ing the 2.4 GHz frequency band with Bluetooth Also calledWi-Fi, the 802.11b standard is used to connect devices toWLANs, and allows a maximum throughput of 11 Mbps Thetechnology is being used in a number of WLAN settings,such as college campuses, business parks, office buildings,and even private homes It is also being implemented by anumber of vendors in public places such as airports, hotels,and cafes to give users of notebook computers, handhelddevices, and smartphones wireless Internet access any-where inside those locations

shar-Wireless technologies and services have become so popularworldwide and sufficiently sophisticated and complex as tomerit dozens of books on the topic that are published everyyear This encyclopedia is a quick reference that clearlyexplains the essential concepts of wireless, including services,applications, protocols, network methods, developmenttools, administration and management, standards, and reg-ulation It is designed as a companion to other books youmay want to read about wireless, providing clarification ofconcepts that may not be fully covered elsewhere

The information contained in this book, especially as itrelates to specific vendors and products, is believed to be accu-rate at the time it was written and is, of course, subject tochange with continued advancements in technology and shifts

in market forces Mention of specific products and services isfor illustration purposes only and does not constitute anendorsement of any kind by either the author or the publisher

Nathan J Muller

ACCESS POINTS

An access point (AP) provides the connection between one ormore wireless client devices and a wired local area network(LAN) The AP is usually connected to the LAN via aCategory-5 cable connection to a hub or switch Clientdevices communicate with the AP over the wireless link, giv-ing them access to all other devices through the hub orswitch, including a router on the other side of the hub, whichprovides Internet access (Figure A-1)

An AP that adheres to the IEEE 802.11b Standard foroperation over the unlicensed 2.4-GHz band supports a wire-less link with a data transfer speed of up to 11 Mbps, while

an AP that adheres to the IEEE 802.11a Standard for tion over the unlicensed 5-GHz band supports a wireless linkwith a data transfer speed of up to 54 Mbps Access pointsinclude a number of the following functions and features:

opera-● Radio power control for flexibility and ease of networkingsetup

● Dynamic rate scaling, mobile Internet Protocol (IP) tionality, and advanced transmit/receive technology toenable multiple access points to serve users on the move

func-1

● Built-in bridging and repeating features to connect ings miles apart (The use of specialty antennas increasesrange The AP can support simultaneous bridging andclient connections.)

build-● Wired Equivalent Privacy (WEP), which helps protectdata in transit over the wireless link between the clientdevice and the AP, via 64-, 128-, or 256-bit encryption

● Access control list (ACL) and virtual private network(VPN) compatibility to help guard the network fromintruders

● Statistics on the quality of the wireless link (Figure A-2)

● Configurability using the embedded Web browser

Consumer-level APs stress ease of setup and use (FigureA-3) Many products are configured with default settings

Ethernet

Wireless Clients

Internet Hub

Router

Access Point

Figure A-1 Asimple configuration showing the relationship of the access point to the wired and wireless segments of the network.

ACCESS POINTS 3

that allow the user to plug in the device and use the wirelessconnection immediately Later, the user can play with theconfiguration settings to improve performance and set upsecurity

Although APs adhere to the IEEE 802.11 Standards, ufacturers can include some proprietary features thatimprove the data transfer speed of the wireless link Forexample, one vendor advertises a “turbo mode” that option-ally increases the maximum speed of IEEE 802.11b wirelesslinks from 11 to 22 Mbps When this turbo feature is applied

man-to IEEE 802.11a wireless links, the maximum speed isincreased from 54 to 72 Mbps

Figure A-2 The 5-GHz DWL-5000 Access Point from

D-Link Systems, Inc., keeps the client device notified of the

sta-tus of the wireless link In this case, the signal is at

maximum strength and is capable of a data transfer rate of

48 Mbps.

4 ACCESS POINTS

Enterprise-level APs provide more management features,allowing LAN administrators to remotely set up and configuremultiple APs and clients from a central location For monitor-ing and managing an entire wireless LAN infrastructure con-sisting of hundreds or even thousands of access points,however, a dedicated management system is usually required.Such systems automatically discover every AP on the networkand provide real-time monitoring of an entire wireless networkspread out over multiple facilities and subnets These manage-ment systems support the Simple Network ManagementProtocol (SNMP) and can be tied into higher-level managementplatforms such as Hewlett-Packard’s OpenView

Figure A-3 An example of a consumer AP is this 5-GHz wireless access point (WAP54A) from Linksys, which features antenna with a range of up

to 328 feet indoors.

ACCESS POINTS 5

Among the capabilities of these wireless managers is port of remote reboot, group configuration, or group softwareuploads for all the wireless infrastructure devices on the net-work In addition, the LAN administrator can see how manyclient devices are connected to each access point, monitorthose connections to measure link quality, and monitor allthe access points for performance

sup-Some enterprise APs provide dual-band wireless tions to support both IEEE 802.11a and 802.11b client users

connec-at the same time This is accomplished by equipping the APwith two plug-in radio cards—one that supports the 2.4-GHzfrequency specified by the IEEE 802.11b Standard and onethat supports the 5-GHz frequency specified by the IEEE802.11a Standard

The choice of a dual-band AP provides organizations with

a migration path to the higher data transfer speeds availablewith IEEE 802.11a while continuing to support their existinginvestment in IEEE 802.11b infrastructure Depending onmanufacturer, these dual-band APs are modular so that theycan be upgraded to support future IEEE 802.11 technologies

as they become available, which further protects an zation’s investment in wireless infrastructure

organi-Summary

Access points are the devices that connect wireless clientdevices to the wired network They are available in con-sumer and commercial versions, with the latter generallycosting more because of more extensive management capa-bilities and troubleshooting features They may have moresecurity features as well and support both the 2.4- and 5-GHz frequency bands with separate radio modules that pluginto the same unit

See also

Bluetooth

Wired Equivalent Privacy

Wireless Fidelity

6 ADVANCED MOBILE PHONE SERVICE

Wireless LANs

Wireless Security

ADVANCED MOBILE PHONE SERVICE

Before the age of digital services, the predominant technologyfor analog cellular phone services in North America adhered

to a set of standards for Advanced Mobile Phone Service(AMPS) Originally, AMPS operated in the 800-MHz fre-quency band using 30-kHz-wide channels Avariant of AMPS,known as Narrowband AMPS (NAMPS), uses 10-kHz-widechannels and consequently has triple the capacity of AMPS.Although AMPS or a variation of AMPS is still around—chances are that your cellular phone allows you to switchbetween analog and digital mode—its use is rapidly declining

in the face of more sophisticated digital cellular standards.The mobile telephone service that preceded AMPS wasknown as Improved Mobile Telephone Service (IMTS), whichoperated in several frequency ranges: 35 to 44 MHz, 152 to

158 MHz, and 454 to 512 MHz But IMTS suffered from callsetup delay, poor transmission, and limited frequency reuse.AMPS overcame the limitations of IMTS and set the stagefor the explosive growth of cellular service, which continuestoday worldwide Interestingly, Pacific Bell finally droppedIMTS in 1995

Proposed by AT&T in 1971, AMPS is still the standard foranalog cellular networks It was tested in 1978, and in theearly 1980s cellular systems based on the standards wereinstalled throughout North America Although AMPS wasnot the first system for wireless telephony, the existence of asingle set of standards enabled the United States to domi-nate analog cellular throughout the 1980s Today, Europedominates cellular primarily because it is a lower-cost alter-native to conventional telephone service

Analog cellular is delivered from a system of cellular hubsand base stations with associated radio towers Amobile

ADVANCED MOBILE PHONE SERVICE 7

telecommunications switching office (MTSO) authenticateswireless customers before they make calls, switches callsbetween cells as mobile phone users travel across cell bound-aries, and places calls from land-based telephones to wire-less customers

AMPS uses a technique called “frequency reuse” to greatlyincrease the number of customers that can be served at thesame time Low-powered mobile phones and radio equipment

at each cell site permit the same radio frequencies to bereused in different cells, multiplying calling capacity withoutcreating interference This spectrum-efficient method con-trasts sharply with earlier mobile systems that used a high-powered, centrally located transmitter to communicate withhigh-powered mobile equipment installed in vehicles over asmall number of frequencies Once a channel was occupiedwith a call, its frequency could not reused over a wide area.Despite the success of AMPS, this method of transmissionhas its limitations Analog signals can be intercepted easilyand suffer signal degradation from numerous sources, such

as terrain, weather, and traffic volume Analog systems alsocould not handle the transmission of data very well Adigi-tal version of AMPS—referred to as DAMPS—solves many

of these problems while providing increased capacity and agreater range of services Both AMPS and DAMPS operate

in the 800-MHz band and can coexist with each other.DAMPS is implemented with Time Division Multiple Access(TDMA) as the underlying technology, which provides 10 to

15 times more channel capacity than AMPS and allows theintroduction of new feature-rich services such as data com-munications, voice mail, call waiting, call diversion, voiceencryption, and calling-line identification

Adigital control channel available with DAMPS supportssuch advanced features as a sleep mode, which increases bat-tery life on newer cellular phones by as much as 10 times overthe current battery capabilities of analog phones DAMPSalso can be implemented with Code Division Multiple Access(CDMA) technology to increase channel capacity by as much

8 AIR-GROUND RADIOTELEPHONE SERVICE

as 20 times and provide a comparable range of services andfeatures Unlike TDMA, which can be added onto existingAMPS infrastructure, CDMA requires an entirely new net-work infrastructure

DAMPS also allows operators to build overlay networksusing small micro- and picocells, boosting network capacitystill further in high-traffic areas and providing residentialand business in-building coverage Advanced software in thenetworks’ exchanges continuously monitors call quality andmakes adjustments, such as handing calls over to differentcells or radio channels, when necessary The network man-agement system provides an early warning to the networkoperator if the quality of service is deteriorating so that stepscan be taken to head off serious problems Graphical dis-plays of network configuration and performance statisticshelp ensure maximum service quality for subscribers

Summary

In 1983, AMPS was approved by the Federal CommunicationsCommission (FCC) and first used in Chicago In order toencourage competition and keep prices low, the U.S govern-ment required the presence of two carriers in every market,known as Aand B carriers One of the carriers was normallythe Local Exchange Carrier (LEC); in other words, the localphone company

See also

Cellular Data Communications

Cellular Voice Communications

AIR-GROUND RADIOTELEPHONE SERVICE

With the Air-Ground Radiotelephone Service, a commercialmobile radio service (CMRS) provider offers two-way voice,

AIR-GROUND RADIOTELEPHONE SERVICE 9

fax, and data service for hire to subscribers in aircraft—inflight or on the ground Service providers must apply for anFCC license for each and every tower/base site There aretwo versions of this service: one for general aviation and onefor commercial aviation

General Aviation Air-Ground Service

Air-Ground Radiotelephone Service has been available togeneral aviation for more than 30 years General AviationAir-Ground systems may operate in the 454.675- to 454.975-MHz and 459.675- to 459.975-MHz bands to provide service

to private aircraft, specifically, small single-engine craft andcorporate jets

The service is implemented through general aviationair-ground stations, which comprise a network of indepen-dently licensed stations These stations employ a stan-dardized duplex analog technology called “Air-GroundRadiotelephone Automated Service” (AGRAS) to providetelephone service to subscribers flying over the UnitedStates or Canada Because there are only 12 channelsavailable for this service, it is not available to passengers

on commercial airline flights

Commercial Aviation Air-Ground Systems

Commercial Aviation Air-Ground Systems may operate on

10 channel blocks in the 849- to 851-MHz and 894- to MHz bands These nationwide systems employ various ana-log or digital wireless technologies to provide telephoneservice to passengers flying in commercial aircraft over theUnited States, Canada, and Mexico Some systems havesatellite-calling capability as well, where the call is sent to

896-an earth station instead of the base station

Passengers use credit cards or prearranged accounts tomake telephone calls from bulkhead-mounted telephones

or, in larger jets, from seatback-mounted telephones This

10 AIR-GROUND RADIOTELEPHONE SERVICE

service was available from one company on an experimentalbasis during the 1980s and began regular competitive oper-ations in the early 1990s There are currently three operat-ing systems, one of which is GTE Airfone, a subsidiary ofVerizon Communications

When an Airfone call is placed over North America, mation is sent from the phone handset to a receiver in theplane’s belly and then down to one of the 135 strategicallyplaced ground radio base stations From there, it is sent toone of three main ground switching stations and then over

infor-to the public telephone network infor-to the receiving party’s tion When an Airfone call is placed over water, information

loca-is sent first to an orbiting satellite From there, the calltransmission path is similar to the North American system,except that calls are sent to a satellite earth station instead

of a radio base station Calls can be placed to any domestic

or international location

To receive calls aboard aircraft, the passenger musthave an activation number In the case of Airfone, an acti-vation number can be obtained by dialing 0 toll-freeonboard or 1-800-AIRFONE from the ground For eachflight segment, the activation number will be the same.However, the passenger must activate the phone for eachflight segment and include his or her seat number Theperson placing the call from the ground dials 1-800-AIR-FONE and follows the voice prompts to enter the passen-ger’s activation number The passenger is billed for the call

on a calling card or credit card but gets to choose whether

or not to accept the calls

The following steps are involved in receiving a call:

● The phone will ring on the plane, and the screen will cate a call for the seat location

indi-● The passenger enters a personal identification number(PIN) to ensure that no one else can answer the call

● The phone number of the calling party will be displayed

on the screen

AIR-GROUND RADIOTELEPHONE SERVICE 11

● If the call is accepted, the passenger is prompted to slide

a calling card or credit card to pay for the call

● Once the call has been accepted, the passenger is matically connected to the party on the ground

auto-● If the passenger chooses not to accept the call, he or shefollows the screen prompts, and no billing will occur.Air-to-ground calls are very expensive The cost to placedomestic calls using GTE’s Airfone Service, for example, is

$2.99 to connect and $3.28 per minute or partial minute,plus applicable tax By comparison, AT&T’s InflightCalling costs $2.99 to connect plus $2.99 per minute.These rates apply to all data/fax and voice calls Evencalls to 800 and 888 numbers—which are normally toll-free on the ground—are charged at the same rate as regu-lar Airfone and Inflight calls No billing ever occurs for theground party The charges for international calls arehigher; both AT&T and GTE charge $5.00 to connect and

$5.00 per minute GTE offers satellite service for use overthe ocean and worldwide at $10.00 to connect and $10.00per minute, but the service is available only on UnitedAirlines

Summary

FCC rules specifically prohibit the use of cellular mitters on aircraft, except for aircraft on the ground Thisprohibition was not done to protect the aircraft’s avionicssystems from interference from the cellular transmitter.Rather, this prohibition was made to protect the cellularservice on the ground from interference As the altitude of

trans-a cellultrans-ar htrans-andheld trtrans-ansmitter incretrans-ases, its rtrans-ange trans-alsoincreases and, consequently, its coverage area At highaltitudes, such as would be achieved from an in-flight air-craft, the hand-held unit places its signal over several cel-lular base stations, preventing other cellular users withinrange of those base stations from using the same frequency

12 AMATEUR RADIO SERVICE

This would increase the number of blocked or dropped lular calls

cel-See also

Cellular Data Communications

Cellular Voice Communications

AMATEUR RADIO SERVICE

Amateur Radio Service is defined by the FCC as “A radiocommunication service for the purpose of self-training, inter-communication, and technical investigations carried out byamateurs; that is, duly authorized persons interested inradio technique solely with a personal aim and without pecu-niary interest.”1

Amateur radio stations are licensed by the FCC and mayengage in domestic and international communications—both two-way and one-way Applications for new licenses orfor a change in operator class are filed through a volunteerexaminer-coordinator (VEC) Operators can use their sta-tion equipment as soon as they see that information abouttheir amateur operator/primary station license grantappears on the amateur service database New operators

do not need to have the license document in their sion to commence operation of an amateur radio station.Since amateur stations must share the air waves, eachstation licensee and each control operator must cooperate inselecting transmitting channels and in making the mosteffective use of the amateur service frequencies Aspecifictransmitting channel is not assigned for the exclusive use ofany amateur station

AMATEUR RADIO SERVICE 13

Types of Communications

With regard to two-way communications, amateur stationsare authorized to exchange messages with other stations inthe amateur service, except those in any country whoseadministration has given notice that it objects to such com-munications.2In addition, transmissions to a different coun-try must be made in plain language Communication islimited to messages of a technical nature relating to testsand to remarks of a personal nature for which, by reason oftheir unimportance, use of public telecommunications ser-vices is not justified

Amateur radio stations also may engage in one-way munications For example, they are authorized to transmitauxiliary, beacon, and distress signals Specifically, an ama-teur station may transmit the following types of one-waycommunications:

com-● Brief transmissions necessary to make adjustments to thestation

● Brief transmissions necessary for establishing two-waycommunications with other stations

● Transmissions necessary to provide emergency cations

communi-● Transmissions necessary for learning or improving ciency in the use of international Morse code

profi-● Transmissions necessary to disseminate an informationbulletin of interest to other amateur radio operators

14 AMATEUR RADIO SERVICE

there are several types of amateur-operator communicationsthat are specifically prohibited, including

● Transmissions performed for compensation

● Transmissions done for the commercial benefit of the tion control operators

sta-● Transmissions done for the commercial benefit of the tion control operator’s employer

sta-● Transmissions intended to facilitate a criminal act

● Transmissions that include codes or ciphers intended toobscure the meaning of the message

● Transmissions that include obscene or indecent words orlanguage

● Transmissions that contain false or deceptive messages,signals, or identification

● Transmissions on a regular basis that could reasonably befurnished alternatively through other radio servicesBroadcasting information intended for the general public isalso prohibited Amateur stations may not engage in any form

of broadcasting or in any activity related to program tion or newsgathering for broadcasting purposes The oneexception is when communications directly related to theimmediate safety of human life or the protection of propertymay be provided by amateur stations to broadcasters for dis-semination to the public where no other means of communica-tion is reasonably available before or at the time of the event.Amateur stations are not afforded privacy protection.This means that the content of the communications by ama-teur stations may be intercepted by other parties anddivulged, published, or used for another purpose

produc-Summary

In August 1999, the FCC’s Wireless TelecommunicationsBureau (WTB) began the transition to the Universal Licensing

AMATEUR RADIO SERVICE 15

System (ULS) for all application and licensing activity in theAmateur Radio Services As of February 2000, amateurlicensees were required to file using ULS forms, which meansthat applications using Forms 610 and 610V are no longeraccepted by the WTB.3The ULS is an interactive licensingdatabase developed by the WTB to consolidate and replace 11existing licensing systems used to process applications andgrant licenses in wireless services ULS provides numerousbenefits, including fast and easy electronic filing, improveddata accuracy through automated checking of applications,and enhanced electronic access to licensing information

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to provide wireless telephone service to subscribers in remoteareas where it would be impractical to provide wireline tele-phone service The wireless link allows up to four subscribers

to use a single radio channel pair simultaneously withoutinterfering with one another

Licensed by the Federal Communications Commission(FCC) under the Rural Radiotelephone Service, BETRS may

be licensed only to state-certified carriers in the area wherethe service is provided and is considered a part of the PublicSwitched Telephone Network (PSTN) by state regulators.This service operates in the paired 152/158- and 454/459-MHz bands and on 10 channel blocks in the 816- to 820-MHzand 861- to 865-MHz bands These channels are also allo-cated for paging services Since BETRS primarily servesrural areas in the western part of the United States, it typi-cally does not conflict geographically with paging services.When there is a conflict, the FCC provides a remedy

17

Rural Radiotelephone Service and BETRS providersobtain site licenses and operate facilities on a secondarybasis This means that if any geographic area licensee sub-sequently notifies the Rural Radiotelephone Service orBETRS licensee that a facility must be shut down because itmay cause interference to the paging licensee’s existing orplanned facilities, the Rural Radiotelephone Service orBETRS licensee must discontinue use of the particular chan-nel at that site no later than 6 months after such notice

Summary

BETRS primarily serves rural, mountainous, and sparselypopulated areas that might not otherwise receive basic tele-phone service Although the industry has raised concernsthat auctioning spectrum for BETRS would have the effect

of raising the cost of the service, which could deprive theseareas of basic telephone service, the FCC does not distin-guish BETRS from other services that use radio spectrum toprovide commercial communication services

BLUETOOTH 19

Applications

Among the many things users can do with Bluetooth is swapdata and synchronize files merely by having the devicescome within range of one another Images captured with adigital camera, for example, can be dropped off at a personalcomputer (PC) for editing or a color printer for output onphoto-quality paper—all without having to connect cables,load files, open applications, or click buttons

The technology is a combination of circuit switching andpacket switching, making it suitable for voice as well asdata Instead of fumbling with a cell phone while driving, forexample, the user can wear a lightweight headset to answer

a call and engage in a conversation even if the phone istucked away in a briefcase or purse

While useful in minimizing the need for cables, wirelesslocal area networks (LANs) are not intended for intercon-necting the range of mobile devices people carry aroundeveryday between home and office For this, Bluetooth isneeded And in the office, a Bluetooth portable device can be

TABLE B-1 Performance Characteristics of Bluetooth Products

Connection type Spread spectrum (frequency hopping) Spectrum 2.4-GHz ISM (industrial, scientific, and

medical) band Transmission power 1 milliwatt (mW)

Aggregate data rate 1 Mbps using frequency hopping

Supported stations Up to eight devices per piconet

Voice channels Up to three synchronous channels Data security For authentication, a 128-bit key; for

encryption, the key size is configurable between 8 and 128 bits

Addressing Each device has a 48-bit Media Access

Control (MAC) address that is used to establish a connection with another device

The devices within a piconet play one of two roles: that ofmaster or slave The master is the device in a piconet whoseclock and hopping sequence are used to synchronize all otherdevices (i.e., slaves) in the piconet The unit that carries outthe paging procedure and establishes a connection is bydefault the master of the connection The slaves are theunits within a piconet that are synchronized to the mastervia its clock and hopping sequence

The Bluetooth topology is best described as a piconet structure Since Bluetooth supports both point-to-point and point-to-multipoint connections, several piconetscan be established and linked together in a topology called a

multiple-“scatternet” whenever the need arises (Figure B-1)

Piconets are uncoordinated, with frequency hoppingoccurring independently Several piconets can be establishedand linked together ad hoc, where each piconet is identified

by a different frequency-hopping sequence All users ipating on the same piconet are synchronized to this hoppingsequence Although synchronization of different piconets isnot permitted in the unlicensed ISM band, Bluetooth unitsmay participate in different piconets through Time DivisionMultiplexing (TDM) This enables a unit to sequentially par-ticipate in different piconets by being active in only onepiconet at a time

partic-With its service discovery protocol, Bluetooth enables amuch broader vision of networking, including the creation of

BLUETOOTH 21

personal area networks, where all the devices in a person’slife can communicate and work together Technical safe-guards ensure that a cluster of Bluetooth devices in publicplaces, such as an airport lounge or train terminal, wouldnot suddenly start talking to one another

Technology

Two types of links have been defined for Bluetooth in port of voice and data applications: an asynchronous connec-tionless (ACL) link and a synchronous connection-oriented(SCO) link ACL links support data traffic on a best-effortbasis The information carried can be user data or controldata SCO links support real-time voice and multimediatraffic using reserved bandwidth Both data and voice arecarried in the form of packets, and Bluetooth devices cansupport active ACL and SCO links at the same time.ACL links support symmetric or asymmetric packet-switched point-to-multipoint connections, which are typically

sup-Master Master Master

22 BLUETOOTH

used for data For symmetric connections, the maximum datarate is 433.9 kbps in both directions, send and receive Forasymmetric connections, the maximum data rate is 723.2kbps in one direction and 57.6 kbps in the reverse direction

If errors are detected at the receiving device, a notification issent in the header of the return packet so that only lost or cor-rupt packets need to be retransmitted

SCO links provide symmetric circuit-switched point connections, which are typically used for voice Threesynchronous channels of 64 kbps each are available for voice.The channels are derived through the use of either PulseCode Modulation (PCM) or Continuous Variable Slope Delta(CVSD) Modulation PCM is the standard for encodingspeech in analog form into the digital format of ones andzeros CVSD is another standard for analog-to-digital encod-ing but offers more immunity to interference and therefore

point-to-is better suited than PCM for voice communication over awireless link Bluetooth supports both PCM and CVSD; theappropriate voice-coding scheme is selected after negotia-tions between the link managers of each Bluetooth devicebefore the call takes place

Voice and data are sent as packets Communication ishandled with Time Division Duplexing (TDD), which dividesthe channel into time slots, each 625 microseconds (µs) inlength The time slots are numbered according to the clock ofthe piconet master In the time slots, master and slave cantransmit packets In the TDD scheme, master and slavealternatively transmit (Figure B-2) The master starts itstransmission in even-numbered time slots only, and theslave starts its transmission in odd-numbered time slotsonly The start of the packet is aligned with the slot start.Packets transmitted by the master or the slave may extendover as many as five time slots

With TDD, bandwidth can be allocated on an as-neededbasis, changing the makeup of the traffic flow as demandwarrants For example, if the user wants to download a largedata file, as much bandwidth as is needed will be allocated