Research On Construction Of Polar Codes In LEO Satellite Communication

The LEO satellite communication system has great significance and broad application prospects in the communication field.The performance of Polar codes in LEO satellite communications is mainly studied in the thesis with an improved polarization weight construction algorithm proposed under block fading channels,which has important theoretical and practical significance.In this thesis,according to the speed of channel transmission characteristics changing with time,the LEO satellite channels are divided into three cases: changing slowly,changing slowly in fixed period,and changing fast.Then they are modeled as AWGN channels,block fading channels,and Corazza channels,respectively.At the same time,based on the introduction of basic theories with coding and decoding algorithms of Polar codes,the construction algorithms are also studied.In the case of block fading channels,the thesis considers the role of the fading coefficients as a process of "fading polarization",and has proposed an improved polarization weight construction method to improve the BER performance.Afterwards,in order to study the performance of Polar codes in LEO satellite communications,the performance of Polar codes and LDPC codes recommended by CCSDS is compared under AWGN channels,block fading channels and Corazza channels.They are(2048,1024)Polar codes compared to(2048,1024)LDPC codes and(8192,7168)Polar codes compared to(8176,7154)LDPC codes.The simulation results show that the performance of(8192,7168)Polar codes is not as good as LDPC codes,while(2048,1024)Polar codes have performance gains compared to(2048,1024)LDPC codes.In short,in the case of medium code length and rate,using Polar codes in LEO satellite communications can achieve performance gains.And because of the low complexity of coding and decoding methods,Polar codes will have broad application prospects in LEO satellite communications.