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Chapter 9Using Telephoneand Cable Networksfor Data TransmissionCopyright The McGraw-Hill Companies,Inc.Permission required for reproduction or display.19-1 TELEPHONE NETWORKTelephone Telephone networks networks use use circuit circuit switching.switching.The The telephone telephone network network had had its its beginnings beginnings in in the the late late 1800s.1800s.The The entire entire network,network,which which is is referred referred to to as as the the plain plain old old telephone telephone systemsystem (POTSPOTS),),was was originally originally an an analog analog system using analog signals to transmit voice.system using analog signals to transmit voice.Major ComponentsLATAsSignalingServices Provided by Telephone NetworksTopics discussed in this section:Topics discussed in this section:2Figure 9.1 A telephone system3Intra-LATA services are provided by local exchange carriers.Since 2019,there are twotypes of LECs:incumbent local exchange carriers and competitive local exchange carriers.Note4Figure 9.2 Switching offices in a LATA5Figure 9.3 Point of presences(POPs)6The tasks of data transfer and signaling are separated in modern telephone networks:data transfer is done by one network,signaling by another.Note7Figure 9.4 Data transfer and signaling networks8Figure 9.5 Layers in SS799-2 DIAL-UP MODEMSTraditional Traditional telephone telephone lines lines can can carry carry frequencies frequencies between between 300 300 and and 3300 3300 Hz,Hz,giving giving them them a a bandwidth bandwidth of of 3000 3000 Hz.Hz.All All this this range range is is used used for for transmitting transmitting voice,voice,where where a a great great deal deal of of interference interference and and distortion distortion can can be accepted without loss of intelligibility.be accepted without loss of intelligibility.Modem StandardsTopics discussed in this section:Topics discussed in this section:10Figure 9.6 Telephone line bandwidth11Modemstands for modulator/demodulator.Note12Figure 9.7 Modulation/demodulation13Figure 9.8 The V.32 and V.32bis constellation and bandwidth14Figure 9.9 Uploading and downloading in 56K modems159-3 DIGITAL SUBSCRIBER LINEAfter After traditional traditional modems modems reached reached their their peak peak data data rate,rate,telephone telephone companies companies developed developed another another technology,technology,DSL,DSL,to to provide provide higher-speed higher-speed access access to to the the Internet.Internet.Digital Digital subscriber subscriber lineline (DSLDSL)technology technology is is one one of of the the most most promising promising for for supporting supporting high-speed high-speed digital digital communication over the existing local munication over the existing local loops.ADSLADSL LiteHDSLSDSLVDSLTopics discussed in this section:Topics discussed in this section:16ADSL is an asymmetric communication technology designed for residential users;it is not suitable for businesses.Note17The existing local loops can handle bandwidths up to 1.1 MHz.Note18ADSL is an adaptive technology.The system uses a data ratebased on the condition of the local loop line.Note19Figure 9.10 Discrete multitone technique20Figure 9.11 Bandwidth division in ADSL21Figure 9.12 ADSL modem22Figure 9.13 DSLAM23Table 9.2 Summary of DSL technologies249-4 CABLE TV NETWORKSThe The cable cable TV TV networknetwork started started as as a a video video service service provider,provider,but but it it has has moved moved to to the the business business of of Internet Internet access.access.In In this this section,section,we we discuss discuss cable cable TV TV networks networks per per se;se;in in Section Section 9.5 9.5 we we discuss discuss how how this this network network can can be used to provide high-speed access to the Internet.be used to provide high-speed access to the Internet.Traditional Cable NetworksHybrid Fiber-Coaxial(HFC)NetworkTopics discussed in this section:Topics discussed in this section:25Figure 9.14 Traditional cable TV network26Communication in the traditional cable TV network is unidirectional.Note27Figure 9.15 Hybrid fiber-coaxial(HFC)network28Communication in an HFC cable TV network can be bidirectional.Note299-5 CABLE TV FOR DATA TRANSFERCable Cable companies companies are are now now competing competing with with telephone telephone companies companies for for the the residential residential customer customer who who wants wants high-speed high-speed data data transfer.transfer.In In this this section,section,we we briefly briefly discuss this technology.discuss this technology.BandwidthSharingCM and CMTSData Transmission Schemes:DOCSISTopics discussed in this section:Topics discussed in this section:30Figure 9.16 Division of coaxial cable band by CATV31Downstream data are modulated using the 64-QAM modulation technique.Note32The theoretical downstream data rateis 30 Mbps.Note33Upstream data are modulated using the QPSK modulation technique.Note34The theoretical upstream data rate is 12 Mbps.Note35Figure 9.17 Cable modem(CM)36p经常不断地学习,你就什么都知道。你知道得越多,你就越有力量pStudyConstantly,AndYouWillKnowEverything.TheMoreYouKnow,TheMorePowerfulYouWillBe写在最后Thank You在别人的演说中思考，在自己的故事里成长Thinking In Other PeopleS Speeches，Growing Up In Your Own Story讲师：XXXXXX XX年XX月XX日
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