Research And Application Of ADSL

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 technology that provides high-speed, asymmetric data access, synchronously the potential of Twisted Pair(TP) is utilized, and the Plain Old Telephone Service(POTS) is not interrupted. As an implementing method of Multi-Carrier Modulation(MCM), Discrete Multi-Tone (DMT) modulation uses Inverse Discrete Fourier Transform(IDFT) vector as its modulating vector, and Discrete" Fourier Transibrm(DFT) vector as its demodulating vector, and the process of modulating and demodulating can be realized by using their fast calculating method. Bits transmitted by every subchannel are determined by its value of Signal to Noise Ratio(SNR), and the unwanted power caused by noise is distributed to every subchannel, so their damage is weakened. In addition, Reed-Solomon(RS) coding and interleaving are applied to correct long outburst error, so the performance of the system is enhanced once more. Based on theoretical research, the article expounds the project and implement of Digital Subscriber Loop Access Multiplexer(DSLAM)-central office equipment of ADSL system. And the practical testing result effectively proves the practicality of ADSL.