The Study Of Multi-user Broadband Access Technology

With the drastic increase in the demand on the "last-mile" access broadband, the "distance-bandwidth" incompatibility in xDSL becomes more and more pronounced; at the same time, new services such as IPTV, mobile backhaul and other emerging business raise higher requirements on the stability and reliability of xDSL. The traditional xDSL technology enhances the network accessibility of xDSL by strategies such as extending frequency range/spectra, improving power-spectral density, decreasing loop length and denoising crosstalk. However, as the bandwidth of DSL gets extended, the crosstalk between the two wires becomes a disaster, especially in medium distance-range. The noise10～15dB stronger than the normal level has become the biggest cumber-stone compromising the speed, stability, reliability and quality of xDSL.Recently, in response to the crosstalk, the International Telecommunication Union proposed multiple strategies including virtual noise, power back-off and dynamic spectrum management. The current thesis deals with the discrete multi-tone modulation and dynamic spectrum management in the xDSL access technology and a new proposal for the broadband access system. The organization follows:Introduces the evolution of frequency spectral control and the current standardization for frequency spectral management, analyzes the dynamic frequency spectral control and related algorithms in detail, and emulates some of these algorithms.Proposes a new model for DMT modulation and demodulation, which functions by reconstruction of new sequences from parity decomposition in order to reduce the original2N-IFFT/FFT to N-IFFT/FFT, and hence leads to a dramatic decrease in power consumption and chip area.Proposes a new type of line-division duplex broadband access systems, which functions by transmitting the uplink and downlink signals in different cable bundle of twisted pair, and through system simulation and crosstalk elimination of the program in300m distance, symmetric transmission the300Mbps above.