VDSL2Fext Coefficient Algorithm

In the February of2006, ITU-T passed the VDSL2standard, Standard No.G993.2, the Standard is already relatively mature. VDSL2by spectrum spreadingto30MHz, acess to users in the distance1km, can realize the downlink of100Mbit/s high speed data transmission, and provide sufficient bandwidth forvideo service, voice services and internet service. It has good applicationprospect. But in the actual application, the actual rate of VDSL2is far below thestandard maximum rate, it influences the commercial scale of VDSL2to somedegree. FEXT is the main crosstalk in VDSL2, especially on the short loops than500m, and low frequency band from500KHz to5MHz, which lead to the lowerand bad performance of line rate and SNR, so it is the main factor to limit theperformance of VDSL2.This thesis focus on the research of FEXT coefficient algorithm of theVectoring technology based on VDSL2communication system. This algorithm isthe key of the Vectoring technology. This algorithm is mainly to employ the pilotsequence which are loaded on the synchronization symbols to estimate thecrosstalk channel absolutely, and distribute the pilot sequence to the lines withthe a―semidynamic‖manner in order to cut down the time of channel estimation.The algorithm is to use the first-order approximation algorithm to compute the Nrank(N is the number of lines) frequency crosstalk channel inverse matrix. Thethesis uses the pre-coder estimate in the downstream and cancellation estimate inthe upstream to cancel the crosstalk.System clock synchronization is the crosstalk coefficient algorithmprecondition, therefore we carry out the system clock synchronization design andimplementation process, in the end summarize the problems encountered in theprocess of software implementation as well as to solve these problems.In the coefficient algorithm application process, the thesis not just researchthe application of the coefficient algorithm in the system initialization process,but also highlights the coefficient algorithm implemented in software in thetracking feature, as well as the problems and solutions encountered in theprocess.The thesis employs the Matlab software to estimate the crosstalk channel ofVDSL2system, and calculate the line rate and SNR of VDSL2Vectored systemand non Vectored system.In the end, comparing the upstream/downstream linerate and SNR between these two systems in order to find out the advantage ofVectored system.