Polar Coded Relay Cooperation And Networks:Code Constructions And Performance Study

The communication technology has a great influence on people's lifestyle.With the development of modern society,the demand of communication services rises.How to keep the reliability and effectiveness of the communication is always the hotspot in the field of communication research.Channel coding is a kind of method to enhance the reliability of the communication system.At present,the newest channel coding is polar coding which is proposed by Arikan.Polar coding can be proved to achieve Shannon limit in theory and has a low complexity of encoding and decoding.The cooperative communication contributes to the development of communication technology and it can obtain diversity gain and improve the performance of the system by sharing the resource of the users and sending the information through different channels.In this thesis,we investigate the basic principle of polar codes,the systematic polar codes and also combine the polar codes with coded cooperation and network coding.The main research work and innovations are summarized as follows:(1)The traditional channel coding and polar coding are compared and analyzed.Channel polarization phenomenon and the reasons of the polarization are analyzed.On the basic of channel combining and channel splitting,the related formulas are deduced in theory.For the decoding of polar codes,the original algorithm is SC.On the basic of SC,some other algorithms are deduced,such as log likelihood SC decoding algorithm,minimum sum decoding algorithm and the algorithm based on integer quantization.As the improved algorithm of SC,SCL decoding algorithm is also introduced.The simulations are conducted with different decoding algorithms,different conditions of channels and different constructions of polar codes.(2)Polar codes are originally introduced as a class of non-systematic linear block codes.On the analysis of non-systematic polar codes,the encoding and decoding algorithms as well as the encoding complexity of systematic polar codes are studied.Simulation results are given to show that systematic polar codes offer advantages in terms of bit error rate performance.(3)On the basic of investigating systematic polar codes,combining systematic polar codes and cooperative communication technology,a scheme of coded cooperation is proposed with the block diagram of each part.The implementation process of each part and the code rate of the whole cooperative system are analyzed.Compared with the existing coded cooperation based on Plotkin construction,the proposed scheme has better performance.(4)Considering multiple sources,the network coding is adopted.Two kinds of network coding schemes in bidirectional relay communication are studied.One is direct network coding,and the other is physical layer network coding.According to the simulation result,the performance and features of the two schemes are analyzed.A network coding scheme of multiuser cooperation based on polar codes is proposed.The simulation results turn out that the network coding cooperative communication system has better performance than the non-cooperative.Some simulation and analyses of the scheme are carried out under different channels.