Research On Optimization Of Low Complexity SC Decoding Algorithm For Polar Codes

Polar code is a new type of channel coding proposed by Arikan in 2009,and is the only channel coding method that can be rigorously proven to achieve channel capacity,so it is selected as the coding scheme for the 5G Enhanced Mobile Broadband(e MBB)control channel.However,the code length of polar code in the real communication environment is finite,which leads to incomplete polarization of the channel,and most of the channels are between noisy channels and noiseless channels.Therefore,Successive Cancellation(SC)decoding algorithm which relies on channel polarization is difficult to achieve the optimal decoding performance.In order to improve the SC decoding algorithm,Successive Cancellation List(SCL)decoding algorithm and the Soft Cancellation(SCAN)decoding algorithm are proposed,which improve the decoding performance with extra complexity based on SC decoding algorithm.Therefore,this paper addresses the problem of high extra complexity of improved SC decoding algorithms.The work of this paper is summarized as follows:In order to reduce the decoding complexity of SCL algorithm,this paper proposes a simplified critical set(SCS)for SCL decoding algorithm,and applies the simplified critical set to Successive Cancellation List Shifted-Prune(SCL-SP)decoding algorithm,called Simplified Critical Set Assisted Successive Cancellation List Shifted-Prune(SCS-SCL-SP)decoding algorithm.The SCS removes the elements with lower error rates from the traditional critical set based on the polarization of the error distribution of the SCL decoding algorithm to reduce the additional complexity of the decoding algorithm.Simulation results show that the proposed SCS-SCL-SP decoding algorithm reduces the decoding delay by 14.49% without performance loss compared with the traditional SCL-SP decoding algorithm when code length equals1024.In order to solve the problem that the SCAN-Bit Flipping(SCAN-BF)decoding algorithm does not have a suitable flipping candidates set when performing flipping operations,this paper proposes a critical flipping set(CFS)applicable to the SCAN decoding algorithm and a Critical Flipping Set Assisted Soft Cancellation-Bit Flipping(CFS-SCAN-BF)decoding algorithm.The CFS is constructed by performing an analysis of error distribution and the structure of the SCAN decoding algorithm.Simulation results show that at 1024 code length,the decoding delay is reduced by17.70% compared to the traditional SCAN-BF decoding algorithm.In order to further reduce the complexity of the SCL decoding algorithm based on Orthogonal Frequency Division Multiplexing(OFDM)technology,this paper proposes an OFDM-based Partition Successive Cancellation List(OFDM-PSCL)decoding algorithm.Firstly,the channel information obtained from channel estimation is used to segment and order the elements of a critical set,and the segmented checks are used to find the position where the error occurs and an early termination method is used to terminate the incorrect decoding step,minimizing the additional complexity and computational complexity of OFDM-PSCL decoding algorithm.Simulation results show that at 1024 code lengths,the algorithmic complexity is reduced by about22.99% compared to the conventional SCL-SP decoding algorithm.