Construction And Application Of Rate-compatible Polar Codes Based On Polar Spectrum Assistance

Since the creation of information and coding theory,people have been searching for coding techniques that can achieve the Shannon limit.The discovery of polar codes marked the emergence of the first coding technique that could theoretically reach the Shannon limit.Polar codes have the advantages of low complexity of encoding and decoding methods and reachable channel capacity,which are a significant breakthrough in coding theory in the past two decades.In order to realize polar codes encoding of arbitrary code length and code rate to match the actual information transmission,it is particularly critical to design the construction algorithm of rate-compatible polar codes.Therefore,the thesis mainly studies the construction methods of rate-compatible polar codes.The main research contents of the full thesis are summarized as follows:1.Aiming at the problem that puncture algorithm will change the original information set,which affects performance of polar codes further,the coding structure of polar codes is studied firstly,and a MRWP algorithm is proposed according to the structure of generator matrix.Secondly,in order to further optimize puncture mode,different auxiliary puncture schemes are designed on the basis of MRWP algorithm.Finally,polar spectrum is introduced into the construction of puncture polar codes,and the optimal auxiliary puncture scheme is selected as the final auxiliary scheme,which is called a PA-MRWP algorithm.Simulation results show that when code length is 180,code rate is 2/3,and CA-SCL decoding algorithm is used,compared with WQP algorithm,the proposed PA-MRWP algorithm can provide gain of about 0.13 d B at bit error rate of10^-4,and compared with QUP algorithm,the performance of puncture polar codes is significantly improved.In addition,the design idea of PA-MRWP algorithm is extended to the construction of shortening polar codes,and a PA-MRWS algorithm is proposed.Simulation results show that when code length is 384,code rate is 2/3,and the bit error rate is10^-4,compared with RQUP algorithm,the proposed PA-MRWS algorithm can obtain gains of about 0.11 d B and 0.15 d B under the condition of L=4 and L=8,respectively.2.In the actual wireless communication process,wireless channel is usually time-varying fading channel,so the puncture polar codes constructed in this thesis are applied to the BRF channel,and the performance of puncture polar codes based on PA-MRWP algorithm is studied in BRF channel.Simulation results show that for a puncture polar code with code length of 300 and code rate of 2/3,when the bit error rate is10^-4,the proposed PA-MRWP algorithm can provide gains of about 0.27d B and 0.32 d B compared with WQP algorithm under the condition of L=4 and L=8,respectively.