Study On The Vectoring DSL’s Crosstalk Cancellation Algorithm And The ASIC Implementation Of The Offset Value Parallel Computation

Due to the limits of the technologies and spectrum, the crosstalk was usuallyregarded as the background noise in the conventional DSL technology. With therapid development of DSL technology, the spectrum now can reach to30Mhz，;However the loading medium is still the traditional copper cable. This will result inmore serious crosstalk between the lines due to the low isolation in high-frequencyuse. The serious crosstalk can lead to the SNR decrease of the receiving end, thedata rate limitation for the users, high bit error rate, high dropping probability, andsome other problems.To address these problems, the static spectrum management technology anddynamic spectrum management technology has been developed these years.However, the two technologies both have disadvantages while using. And thus atechnology called Vectoring DSL is then proposed. The InternationalTelecommunication Union also adopted a standard protocol named G.993.5todefine this technology.For the practical application of Vectoring DSL, two key challenges should besolved, i.e., the calculation of the crosstalk offsetting coefficient, and the hugecomplex matrix multiplication. The later one aims to get the crosstalk offsettingvalues under the condition of obtained crosstalk offsetting coefficient.In the thesis, a detailed analysis is first given on G.993.5. To implement thecalculation of the crosstalk offsetting coefficient, the direct inversion method, thefirst-order approximation method, and first-order convergence method are analyzedunder the consideration of the characteristics of the G.993.5and related applications.We finally choose the first-order approximation method, which has the advantagesof small calculation amount and high performance, to calculate the crosstalkoffsetting coefficient after comparing the above methods. Considering the numerousadvantages of ASIC technology, the ASIC technology is chosen to complete thecalculation of the crosstalk offsetting values. However in the realization of theASIC, some issues like the large amount of computation and taking up too muchtransmission bandwidth still need to be addressed. This thesis proposes a series ofengineering optimization, including MME data compression, partial crosstalkcancellation, reusing coefficient of multi-tone, to solve the issues.Finally, a detaileddescription about the ASIC implementation of the entire offset value calculation isprovided, including the overall scheme, the divisions of sub-modules, the detailedimplementation of sub-modules, and so on. Meanwhile, the correctness of thedesign is also verified through the experiments. The implementation of theVectoring DSL system prototype is finally performed to test the real improvement of the data rate. The results show that the data rate improves significantly andachieves the expected performance i.e., the rate of above100Mbps downlink.