【作者】 侯鸿飞；

【导师】 李里；

【作者基本信息】 西南交通大学 ， 信息与通信工程， 2022， 硕士

【摘要】 为了满足人们日益增长的无线通信需求,在新一代Wi-Fi协议IEEE 802.11be标准提案中提出将混合自动请求重传技术引入Wi-Fi,提高Wi-Fi链路自适应能力以及提升吞吐量。目前已有一些针对在Wi-Fi中引入混合自动请求重传技术的研究提案,但均没有被IEEE 802.11标准组织采纳,仍存在研究价值。本文主要从重传单元选择以及低密度奇偶校验矩阵固有特性两个方面展开研究。本文针对Wi-Fi中基于低密度奇偶校验码的混合自动请求重传技术进行了深入研究。首先研究了Wi-Fi协议,对协议中数据帧组帧流程、数据帧编码调制流程以及数据帧反馈流程进行了调研,并搭建了相关链路级仿真平台,通过在平台中对相关算法进行实现和仿真,统计其物理特性,并分析其优劣性。然后研究了在IEEE 802.11be中引入混合自动请求重传机制以提高系统通信吞吐量的实现方法。在现存自动请求重传机制上,提出了一种基于码字块重传的混合自动请求重传方案。该方案将重传单元确定为由码字组成的码字块,收发双方按照所设计的规则分解和构成码字块,无需额外信令指示重传信息量及其起始位置。此外,基于码字块重传,信息校验粒度更小,能减少信息重传量。仿真结果表明,得益于以上优点,在大部分信噪比区域内,本文所提混合自动请求重传方案较现有主流标准提案有1.5dB至2dB的能量增益。最后研究了Wi-Fi中的低密度奇偶校验矩阵,提出了一种基于度分布和环长的混合自动请求重传方案,该方案将根据各码长和码率低密度奇偶校验矩阵的度分布和环长特性,优先重传码字中度数高的比特,并根据环长属性从中挑选出在匹配正交频分复用码元过程时需要被剔除的比特。基于此方法将各校验矩阵对应的重传比特固定,无需额外信令指示重传信息量,且不会浪费正交频分复用码元承载信息的能力。仿真结果表明,在中低信噪比区域内,基于度分布和环长混合自动请求重传方案较现有主流标准提案能降低误包率,提高吞吐量。更多还原

【Abstract】 With the increasing demand of wireless communication,the hybrid automatic repeat request technology is introduced into Wi-Fi in the proposal of IEEE 802.11 be standard,which is a new generation of Wi-Fi protocol,to improve the adaptive ability of Wi-Fi link and improve the throughput.At present,there are some research proposals aimed at introducing hybrid automatic repeat request technology into Wi-Fi,but none of them have been adopted by IEEE 802.11 standard organization,so there still have research value.In this thesis,the selection of retransmission unit and the inherent characteristics of low-density parity check matrix are studied.In this thesis,the hybrid automatic repeat request technology based on low density parity code in Wi-Fi is studied in depth.Firstly,the Wi-Fi protocol is studied,and the data frame composing process,data frame coding and modulation process and data frame feedback process in the protocol are investigated,and the related link level simulation platform is built,through the realization and simulation of the related algorithm in the platform,the physical characteristics are statistically analyzed,and its advantages and disadvantages are analyzed.Then,the hybrid automatic repeat request mechanism is introduced in IEEE 802.11 be to improve the system communication throughput.Based on current automatic repeat request mechanism,a codeword block based hybrid automatic repeat request scheme is proposed.A codeword block consisting of a number of code words is employed as retransmission unit in our proposal,at both the transmitter and receiver,the encoding and decoding of data frames could be completed according to predefined rules,and neither additional signaling nor additional information including the amount of retransmitted messages and their coordinates are required.Furthermore,using codeword block as retransmission unit improves the parity-check resolution,and hence potentially avoid some redundant retransmission.The simulation results show that in major fraction of the considered SNR region,our proposal achieves an energy gain around 1.5 to 2dB compared with the performance of the state-of-the-art existed hybrid automatic repeat request proposals for 802.11 be.Finally,the low-density parity check matrix in Wi-Fi is studied,and a hybrid automatic repeat request strategy based on degree distribution and cycle length is proposed,according to the degree distribution and cycle length characteristics of low-density parity check matrix of each code length and code rate,the algorithm will priority retransmit the higher degree bits in the code word,and the bits that need to be removed in the process of matching orthogonal frequency division multiplexing symbols are selected from the cycle length.Based on this method,the retransmission bits corresponding to each check matrix are fixed,without additional signaling indicating retransmission information and without wasting the ability of orthogonal frequency division multiplexing symbols to carry information.Simulation results show that the hybrid automatic request retransmission scheme based on degree distribution and cycle length can reduce the packet error rate and improve the throughput compared with the existing mainstream standard proposals in the middle and low signal to noise ratio region.更多还原