数据通信与网络chapter09

1、9.1chapter 9using telephoneand cable networksfor data transmissioncopyright the mcgraw-hill companies, inc. permission required for reproduction or display.9.2major componentslatassignalingservices provided by telephone networks9.3figure 9.1 a telephone systemendof f i ceslocal l ooptrunktandemof f

2、i cesregi onal of f i cestrunk 9.4intra-lata services are provided by local exchange carriers. since 1996, there are twotypes of lecs: incumbent local exchange carriers and competitive local exchange carriers.note9.5figure 9.2 switching offices in a lata9.6figure 9.3 point of presences (pops)9.7the

3、tasks of data transfer and signaling are separated in modern telephone networks: data transfer is done by one network, signaling by another.note9.8figure 9.4 data transfer and signaling networks9.9figure 9.5 layers in ss79.10modem standards9.11figure 9.6 telephone line bandwidth9.12modemstands for m

4、odulator/demodulator.note9.13figure 9.7 modulation/demodulation9.14figure 9.8 the v.32 and v.32bis constellation and bandwidth9.15figure 9.9 uploading and downloading in 56k modems9.16adsladsl litehdslsdslvdsl9.17adsl is an asymmetric communication technology designed for residential users; it is no

5、t suitable for businesses.note9.18the existing local loops can handle bandwidths up to 1.1 mhz.note9.19adsl is an adaptive technology. the system uses a data ratebased on the condition of the local loop line.note9.20figure 9.10 discrete multitone technique9.21figure 9.11 bandwidth division in adsl9.

6、22figure 9.12 adsl modem9.23figure 9.13 dslam9.24table 9.2 summary of dsl technologies9.25traditional cable networkshybrid fiber-coaxial (hfc) network9.26figure 9.14 traditional cable tv network9.27communication in the traditional cable tv network is unidirectional.note9.28figure 9.15 hybrid fiber-c

7、oaxial (hfc) network9.29communication in an hfc cable tv network can be bidirectional.note9.30bandwidthsharingcm and cmtsdata transmission schemes: docsis9.31figure 9.16 division of coaxial cable band by catv9.32downstream data are modulated using the 64-qam modulation technique.note9.33the theoretical downstream data rateis 30 mbps.note9.34upstream data are modulated using the qpsk modulation technique.note9.35the theoretical ups