Study On Low-latency And High-reliability Channel Coding Based On Hash Function

Channel coding is a keytechnique in future mobile communication.In order to meet the needs of short packet service in 5G and 6G communication systems whose delay ≤5ms and the first transmission success rate should reach 99.999%,finding short codes with low latency and high reliability has become an important goal.As an important short code,Tailing biting Convolutional Code(TBCC)has attracted much attention from all walks of life in the industry.To reduce the HARQ transmission time,the Spinal code as a rateless code has also attracted researchers’ attention.In this paper,the construction and optimization of TBCC,the Hash-TBCCconcatenationscheme and the CRC-Spinal code based on the Hash coding structure are deeply studied.The mainwork is summarized as follows:Firstly,the fundamental of convolutional code is given,and several common decoding algorithms such as Viterbi and BCJRalgorithm are introduced.Then the coding method of TBCC is briefly introduced,and several common TBCC decoding algorithms are given,and the performance of these decoding algorithms is compared and analyzed through simulation.Aiming at the large decoding delayproblem in the decoding algorithm,a list Viterbi decoding algorithm with low delay is introduced,and we analyze and simulate it.The simulation results show that the list Viterbi decoding algorithm has better error correction performance than the traditional Viterbi algorithm,and when the length of the input information is sufficient,the larger the number of lists,the better the decoding performance.In order to improve the reliability of TBCC,we propose a concatenated Hash-TBCC coding scheme,which has the characteristics of flexible concatenated outer code length.The concatenated code Hash function uses the "one at a time" consistent hash function.The concatenation scheme uses the TBCC as inner code and the Hash function as outer code.Besides,the decoding algorithm of our scheme is the list viterbi algorithm and we use the Hash function to choose the final result.Simulation results show that compared with the existing CRC-TBCC,Hash-TBCC has better error correction latency performance when the Hash function and CRC check bits have the same length.Moreover,Hash-TBCC can generate check bits of any length,and only need one Hash encoder,which is more flexible than CRC-TBCC.In order to avoid the delay introduced by HARQ transmission,we introduce a rateless code Spinal code with Hash function as the coding structure,and introduce CRC as the outer code to improve the reliability of Spinal code.To improve the performance of spiral decoding,according to the sequence decoding method of checking multiple surviving paths at the same time in the list Viterbi algorithm,the CRC assisted bubble decoding algorithm is proposed,and different CRC are compared according to the exhaustive method to find the most suitable CRC for the assisted bubble decoding algorithm.The simulation results show that 8 bit CRC cascaded spindle has obvious advantages in bit rate performance and decoding complexity.CRC spike has better error correction performance under 16-QAM and 64-QAM,and the higher the modulation order,the greater the improvement of decoding performance.