| Channel coding is a tool to guarantee the achievement of Shannon bound in telecommunication system. Polar code proposed by Arikan is channel code, could achieve the Shannon bound and has a lower complexity of encoding and decoding. The effective decoding algorithm is a key of Polar code. This thesis focuses on effective decoding algorithm of Polar code. main works are The following:Firstly, the traditional SC decoding, simplified SC decoding based on tree structure(SSC) and list SC decoding(LSC) are described and compare. Compared with SC decoding, LSC has better performance as well as higher complexity. Then a new decoding algorithm, named L-SSC is presented, where the idea of list is introduced into the process of SSC decoding. The numerical simulation results shows that, the L-SSC has a more excellent performance compared with the traditional SSC decoding in the same length of the code and the same the rate of the code. In the condition that length of code is 1024 and the rate of code is 1/2, the profamance of the L-SSC is improved about 0.5dB. With the length of the list increasing, the performance of the L-SSC decoding is more and more better.Secondly, since Cyclic Redundancy Check(CRC) code can decrease the complexity of LSC decoding effectively, a L-SSC with CRC(CRC-L-SSC) code is presented where some of the non-frozen bits are replaced by the CRC codes base on CRC. After the CRC, combined with the idea of adaptive length of list, the adaptive L-SSC Based on the proposed decoding algorithm, a CRC-L-SSC with adaptive list sizeis proposed. The numerical simulation is given: the performance of decoding is more excellent than that with L-SSC decoding algorithm in the same length of the code and the same the rate of the code. In the condition that length of code is 1024 and the rate of code is 1/2, the profamance of the CRC-L-SSC is improved about 0.7dB. Furthermore, the performance of adaptive CRC-L-SSC is more better and self-adaptive when channel characteristics is changed. |
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