Research On Algorithms Of Encoding And Decoding For Polar Code In Rayleigh Fading Channel

In modern society,with the rapid growth of the fifth generation of mobile communication system(5G)and Internet technology technology,it becomes quite convenient,real-time and complete to transmit huge amounts of data to all over the world through digital communication systems.In order to guarantee the reliability of digital communication systems during transmitting process,high attention has been paid to the improvement and research of error correcting codes,which can effectively detect and correct errors.Polar codes appearance are an important achievement of error correcting codes field.Based on channel polarization theory,polar codes mainly calculation Bhattachayya parameters to construct the code words.The key points of construction are shown as:the reliability of polarization channels is simplified by calculation Bhattachayya parameter.The values of reliability are obtained while the information bits can be screened.The key issue of optimal construction is how to calculate the reliability of polarization channels rapidly and accurately.Decoding algorithm is also important for polar codes.At present,the research on decoding algorithms is mainly focused on how to reduce the complexity of the algorithm.Main contributions include:1.Polar codes are constructed not only based on polarization channels,but also for different channel types,so in the third chapter,Rayleigh fading channel is chosen,due to it is more in line with the actual wireless communication channel.Although the Monte Carlo approximation method has good performance and high accuracy,it needs a large number of simulation,and the complexity of the method is very high.The third chapter propose the Rayleigh channel is equivalent to binary erasure channel(BEC)by the optimization of the initial values of Bhattachayya parameters.Finally,by simulation analysis,compared with Monte Carlo approximation method,algorithm proposed in this thesis have the same performance in bit error rate(BER)and lower the computation complexity.2.Because the complexity of add cyclic redundancy check(CRC)list successive cancellation(SCL)decoding algorithm——CA-SCL is too high,so this thesis proposes improved CA-SCL decoding algorithm to reduced the number of decoding paths,meantime,the performance is almost without loss.3.It analyzed the performance of polar codes in orthogonal frequency division multiplexing system(OFDM),polar codes have good performance in OFDMcommunication system by comparing with the tail biting convolutional code.The modulation algorithm of 4th generation of mobile communication system(4G)is improved,and have better performance.