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.Unlike cellular technologies,which provide services to mobile users, fixed wireless ser-vices require a rooftop antenna to an office building or homethat is lined up with a service provider s hub antenna.Fixed wireless access systems come in two varieties: nar-rowband and broadband.Anarrowband fixed wireless accessservice can provide bandwidth up to 128 kbps, which cansupport one voice conversation and a data session such asInternet access or fax transmission.Abroadband fixed wire-less access service can provide bandwidth in the multi-megabit-per-second range, which is enough to supporttelephone calls, television programming, and broadbandInternet access.Anarrowband fixed wireless service requires a wirelessaccess unit that is installed on the exterior of a home or busi-ness (Figure F-3) to allow customers to originate and receivecalls with no change to their existing analog telephones. 104 FIXED WIRELESS ACCESSInternetPSTNInternet Neighborhood128 KbpsAccess AntennaFax CustomerRadioSwitchingCenterFiber LinkExistingInsideWiringFigure F-3 Fixed wireless access configuration.This transceiver is positioned to provide an unobstructedview to the nearest base station receiver.Voice and data callsare transmitted from the transceiver at the customer s loca-tion to the base station equipment, which relays the callthrough the carrier s existing network facilities to the appro-priate destination.No investment in special phones or fac-simile machines is required; customers use all their existingequipment.Narrowband fixed wireless systems use the licensed 3.5-GHz radio band with 100-MHz spacing between uplink anddownlink frequencies.Subscribers receive network accessover a radio link within a range of 200 meters (600 feet) to40 kilometers (25 miles) of the carrier s hub antenna.About2000 subscribers can be supported per cell site.Broadband fixed wireless access systems are based onmicrowave technology.Multichannel Multipoint DistributionService (MMDS) operates in the licensed 2- to 3-GHz fre-quency range, while Local Multipoint Distribution Service(LMDS) operates in the licensed 28- to 31-GHz frequencyrange.Both services are used by Competitive Local Exchange FRAUD MANAGEMENT SYSTEMS 105Carriers (CLECs) primarily to offer broadband Internetaccess.These technologies are used to bring data traffic tothe fiberoptic networks of Interexchange Carriers (IXCs)and nationwide CLECs, bypassing the local loops of theIncumbent Local Exchange Carriers (ILECs).SummaryFixed wireless access technology originated out of the need tocontain carriers operating costs in rural areas, where pole andcable installation and maintenance are more expensive thanin urban and suburban areas.However, wireless access tech-nology also can be used in urban areas to bypass the localexchange carrier for long-distance calls.Since the IXC orCLEC avoids having to pay the ILEC s local loop interconnec-tion charges, the savings can be passed back to the customer.This arrangement is also referred to as a wireless local loop. See alsoCellular Voice CommunicationsLocal Multipoint Distribution ServiceMultichannel Multipoint Distribution ServiceFRAUD MANAGEMENT SYSTEMSFRAUD MANAGEMENT SYSTEMSDespite advances in technology, mobile phone fraud continuesto be an ongoing problem.Fraud management systems thatincorporate mechanisms to integrate service usage data arebecoming a necessary weapon among wireless carriers.Thechallenge is to monitor and profile the activity using harddata and to be alert to the ever-changing nature of fraud.Tocombat cell phone fraud, a number of systems have beenimplemented that can discourage cell phone cloning and stopthieves from obtaining free access to cellular networks
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