Design And Implementation Of LDPC Encoder And Decoder For 5G Communication Systems

At present,research on mobile communication systems has entered the 5G era.Channel coding is one of the key technologies and is mainly used to ensure the correct transmission of channel information and improve the communication quality.In 2016,the 3GPP organization finally decided to use the LDPC code as a data channel coding scheme for the5G eMBB scenario.Compared with 4G,5G has higher requirements on information transmission rate and information transmission reliability.Therefore,researching 5G LDPC coding and decoding algorithms and designing and implementing 5G LDPC encoder and decoder have important application value and significance in the current 5G research boom.In the aspect of 5G LDPC coding,this paper focuses on the simplified approximation of the lower triangular matrix encoding algorithm and the FPGA QC-LDPC encoder designed based on this algorithm.In this paper,the speciality of the H-matrix structure and the particularity of the values of the cyclic shift coefficients of the sub-matrix under the 5G standard are used to simplify the calculation of the check bits in the approximate lower triangular matrix encoding algorithm,rounding down the matrix inversion operation and directly using a simple linear mathematical operation to calculate check bits.The LDPC encoder designed by using this algorithm has only a few cyclic shift registers as the core modules.Compared with the LDPC encoder designed based on the general approximation of the lower triangular matrix encoding algorithm,this design reduces the coding complexity,improves coding efficiency and reduces hardware resource consumption.In the aspect of LDPC decoding,this paper focuses on a layered LDPC decoding algorithm based on the dynamic change of the H-matrix layer processing sequence and the FPGA QC-LDPC decoder designed based on this algorithm.In the traditional layered LDPC decoding algorithm,the speed of decoding convergence is slow and the decoding performance can not get better.In LC-ANS decoding algorithm,the decoding complexity is high and the implementation of decoder is difficult.To solve these issues,a layered LDPC decoding scheme based on the dynamic change of the H-matrix layer processing sequence for 5G systems is proposed in this paper.The H-matrix is layered and the node messages are updated in the order of H-matrix layer processing.In each iteration,the H-matrix processing order is re-ordered by using the value ?_L of each H-matrix layer to obtain the best decoding layer processing order.The simulation results show that compared with the traditional layered LDPC decoding algorithm based on the fixed H-matrix layer processing order,the layered LDPC decoding algorithm proposed in this paper can achieve better decoding performance,and compared with the LC-ANS decoding algorithm,the new algorithm presented in this paper can effectively reduce the decoding complexity.