Research And Simulation On Time Equalization Of Asymmetric Digital Subscriber Line

With the rapid development of Information Technology (IT), especially the universal application of Internet, broadband Access Networks(AN) become more and more prevalent. Asymmetric Digital Subscriber Loop(ADSL) is the best way to carry on broadband transmission utilizing the existing access network (twisted wire-pair) at present.ADSL is a kind of asymmetric copper lines access network technology, it can achieve higher data rates by using the digit coding technique from the existing twisted-pair telephone lines, furthermore, it does not affect the common voice service in the same line. The reason why we call it asymmetric technique is that it assigns most part of its bandwidth to provide the path for subscribers download information and uses a little part of its bandwidth receive the information which subscriber upload, thus it appears a kind of asymmetric transmission mode like this. Adopting this kind of the transmission technique is not only applicable to obtain high-speed data for the consumer to visit the Internet and use the vod system, but also can let up the near crosstalk of port consumedly (NEXT).The discrete multi-tone is an important type of MCM, it is mainly used in wire-line communication system such as ADSL/VDSL. The modulation of DMT is to divide the bandwidth into n independent and the same wide subchannels, according to the performance (such as signal noise ratio, attenuation etc.) of the channel namely the capability of the transport data assigns each subchannel to the self-adapting of input data last. From 1 to n subchannels, the DMT adopts QAM which has different constellations, the output of the constellation drawing coder will still be the different from the...