Polar Code Simplification In 5G And Polar Signal Design In SoftCast

In the fifth generation communication system(5G),people's demand for multimedia video resources such as short videos,live broadcasts,and high-definition movies is increasing.In addition,the transmission of high-definition video resources will bring greater pressure on increasingly tight bandwidth resources.Therefore,a video transmission system with high reliability and high data compression rate is required now.SoftCast is a linear video transmission system of source-channel joint coding of cross-layer transmission.Polar code is the only coding method that can theoretically prove to reach Shannon capacity.In addition,the Hadamard transform in SoftCast has the same structure as the channel polarization in polar code.Based on the consistency of these two transformations,this paper conducts research from two aspects:polar code and SoftCast.In SoftCast,the channel reliability difference generated by polarization transformation is used to protect data,achieving high reliability ana high high data compression rate transmission.Firstly,the principle of polar code and the provisions for polar code encoding in the 5G protocol are introduced.Then,a simplified polar code encoding and decoding scheme is proposed for the problem of a large amount of intermediate data and redundant operations in the protocol.The simplified scheme uses a simplified coding structure that incorporates intermediate processing to reduce redundancy,and simplifies multi-step operations into one step,optimizes the rate adaptation process.So this simplified scheme can effectively reduce storage space and reduce the number of encoding operations.Then,aiming at the problems of low data compression rate and low signal-to-noise ratio(SNR)system performance(PSNR)in SoftCast,the relationship between Hadamard transform,polar code and compressed sensing(CS)was studied.The position number of the non-zero data corresponding to the columns of the perceptual measurement matrix has an impact on the system performance.An improved SoftCast video transmission system based on polarization transformation is designed.In this system,two column selection methods are mainly proposed.The first method,based on the reliability and non-repeatability of the columns,selects the columns of the measurement matrix,called the Polar Column Selection(PCS).In order to further improve the performance of low SNR,the second method,called the Hybrid Column Selection method(HCS),partially modified the first method.That is,some low-reliability columns selected in the first method are replaced by columns with high column weights.Compared with the protocol,the simplified scheme of the polar code proposed in this paper can reduce the number of operations by up to 90%,and the storage space can be reduced by up to 40%or 50%in the case of longer codes.The improved SoftCast video transmission system proposed in this paper improves the PSNR.In addition,the data compression rate is improved.So high compression rate and high reliability video transmission is realized.