Study Of Tail-biting Convolutional Codes And Turbo Codes For 5G Communications

In LTE systems,tail-biting convolutional codes(TBCC)and Turbo codes occupy dominant positions.Nowadays in the coming 5G system,these two coding schemes are also very competitive.In this paper,we make an in-depth analysis and research on TBCC and Turbo codes.In the coming 5G system,the application of channel coding is divided into three scenarios: enhanced mobile broadband(e MBB),large-scale machine communication(m MTC)and ultra-high reliability low delay communication(u RLLC).Among them,the m MTC scenario involves large-scale distributed sensors,requiring channel coding scheme to support from tens to hundreds of bits of short packet transmission.Many companies,including Nokia,support TBCC as an option for short codes in the u RLLC scenario.For the convolutional code,this paper first introduces its coding principle in detail,and presents Viterbi and BCJR decoding algorithms.Then the coding structure of TBCC proposed in LTE system is briefly introduced.At the same time,according to the needs of short code in the 5G scenario,we introduce and analyze several common TBCC decoding algorithms.Also,based on the problems of these decoding algorithms,the corresponding improved decoding algorithms are proposed.Furthermore,the improved decoding algorithms are analyzed and compared from the aspects in terms of performance and complexity,and their advantages and application scenarios are stated.For the Turbo code,this paper first introduces its encoding principle and iterative decoding algorithm specifically.Furthermore,based on the LTE system,the performance simulation of Turbo codes with different bit rates over the AWGN channel is given,and the problems in the 5G system are then pointed out.Moreover,we introduced the coding and decoding principles of the enhanced Turbo code proposed in 3GPP proposal.Finally,We further discuss the influence of different decoding algorithms and their iterations on decoding performance.The simulation results show that the enhanced Turbo code has better performance than that the Turbo code in the LTE system and eliminates the phenomenon that for high code rate Turbo codes,the error floor appears in an early stage.Finally,this paper presents the FPGA design and implementation of TBCC.In the design we use the modular method,and in the calculation of the measurement for the trellis state we used a part of the partially parallel processing methods to improve the throughput rate.In the end,a performance test is implemented on a Xilinx Virtex-6 XC6VLX240 T FPGA chip.