Research On Polarization Coding And Decoding Optimization And Multi-relay Coding Cooperation

At present,research on key technologies of 5G Internet of Things(Io T)has received extensive attention.It uses wireless sensor network(WSN)to realize unified interactive management of information.For many WSN application scenarios,reducing energy consumption and improving signal transmission reliability are the primary issues.For this reason,this article mainly carried out the research of polarization code encoding and decoding and its multi-relay polarization encoding cooperation technology.First,it briefly describes the background of polarization coding collaboration in wireless sensor networks and the current research status.Subsequently,the principle of polarization code encoding and decoding is summarized,and for BP decoding,two early termination iteration methods based on frozen bits are proposed.In addition,in the energy efficiency-oriented WSN,the polarization code construction method when the channel state information is poor is optimized,and a power-constrained multi-relay polarization coding cooperation scheme is thesis.The research content and contributions are as follows:1.Aiming at the problems of high delay and high complexity of the existing polarization code BP decoding,an early termination iterative algorithm based on frozen bit error rate(BER)and frozen bit decision offset is proposed.The former uses the characteristic that the average error probability of frozen bits is much higher than that of information bits,and the convergence trend is the same as that of information bits.Therefore,it is judged whether the information is decoded successfully according to whether the average bit error rate of frozen bits tends to be stable.The latter also uses the characteristics of frozen bits to shift the decision threshold according to the definition of a priori probability and the convergence characteristics of BP parallel decoding.When the log-likelihood ratio(LLR)of all selected frozen bits is greater than the decision threshold,the decoding is terminated.Simulation shows that the two proposed early termination iterative decoding algorithms can achieve the purpose of early termination of iteration,and the overall performance of frozen bit decision offset decoding is better than that of frozen bit BER decoding.When the channel has a low noise level,the number of iterations is reduced by more than 80%without loss of decoding performance,greatly reducing the complexity and time delay of BP decoding,and greatly improving the decoding efficiency of polarization codes.2.In order to solve the problem of low reliability of information transmission due to the complex and changeable channels of the multi-relay cooperative WSN system,an adaptive polarization code construction method based on channel state information(CSI)is proposed.It obtains the number of unreliable channels by comparing the channel attenuation coefficient with the threshold value,and converts a part of the information bit channel into a frozen bit channel in proportion,and then re-encodes to realize the dynamic change of the polarization code rate.Simulation shows that this method can dynamically reduce the polarization code rate in exchange for BER performance when the channel quality is poor.When the BER is 10^-3,compared to the Gaussian estimation and Monte Carlo construction methods,this method has a performance gain of about 0.35d B.3.In view of the mismatch between the number of relays and the signal transmission power caused by the limited total power of the multi-relay cooperative WSN system,the power consumption of the relay circuit is included in the total power,and the optimal relay selection and power allocation scheme is proposed.After pre-selecting relays by channel capacity,this scheme introduces relay ranking and indicator factors,judges participation in cooperation based on the contribution of relay node signals to the received signal-to-noise ratio of the destination node,and allocates power.Simulation shows that this scheme can maximize the received signal-to-noise ratio of the destination node while ensuring the quality of cooperative communication transmission.The number of relay nodes participating in the relay cooperative transmission is independent of the distance between the relay node and the destination node.At the same time,through the joint cooperation of polarization channel coding,the reliability of information transmission is greatly improved.When the signal-to-noise ratio is high,the proposed scheme can obtain a performance gain of about 0.6d B compared with the full-relay strategy scheme.The polarization code studied in this paper terminates the iterative algorithm early,which improves the overall decoding performance.The proposed polarization code construction method combined with the power-constrained multi-relay polarization coding cooperation scheme and power allocation can improve the reliability of cooperative transmission while solving the energy consumption problem,which is very suitable for 5G Io T cooperative wireless Among the sensor networks.