The complexity/performance balanced decoder for low-density parity-check （LDPC） codes is preferred in practical wireless communication systems. A low complexity LDPC decoder for the Consultative Committee for Space ...The complexity/performance balanced decoder for low-density parity-check （LDPC） codes is preferred in practical wireless communication systems. A low complexity LDPC decoder for the Consultative Committee for Space Data Systems （CCSDS） standard is achieved in DSP. An ap- proximate decoding algorithm, normalized rain-sum algorithm, is used in the implementation for its low amounts of computation. To reduce the performance loss caused by the approximation, the pa- rameters of the normalized min-sum algorithm are determined by calculating and finding the mini- mum value of thresholds through density evolution. The minimum value which indicates the best per- formance of the decoding algorithm is corresponding with the optimized parameters. In implementa- tion, the memory cost is saved by decomposing the parity-check matrix into submatrices to store and the computation of passing message in decoding is accelerated by using the intrinsic function of DSP. The performance of the decoder with optimized factors is simulated and compared with the ideal BP decoder. The result shows they have about the same performance.展开更多
As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliabilit...As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.展开更多
利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同...利用变量节点符号可靠度在迭代过程中的分布特征,提出了一种基于可靠度差值特征的自适应判决多元低密度奇偶校验(Low Density Parity Check, LDPC)译码算法。整个迭代过程划分为两个阶段,针对不同阶段节点可靠度的差值特征分别采用不同的判决策略:前期阶段,采用传统的基于最大可靠度的判决策略;后期阶段,根据最大、次大可靠度之间的差值特征,设计自适应的码元符号判决策略。仿真结果表明,所提算法在相当的译码复杂度前提下,能获得0.15~0.4 dB的性能增益。同时,对于列重较小的LDPC码,具有更低的译码错误平层。展开更多
军事卫星通信由于需满足信息实时性、传输速率高、通信容量大以及符合星间链路信道的时变特性等要求,通常采用高编码增益、高吞吐量的信道编码方案。低密度奇偶校验(Low-Density Parity-Check,LDPC)码由于具备接近Shannon极限的优异纠...军事卫星通信由于需满足信息实时性、传输速率高、通信容量大以及符合星间链路信道的时变特性等要求,通常采用高编码增益、高吞吐量的信道编码方案。低密度奇偶校验(Low-Density Parity-Check,LDPC)码由于具备接近Shannon极限的优异纠错性能和可并行计算的特性成为卫星通信主导信道编码标准之一。目前卫星通信接收机的译码器模块设计仍存在诸如无法实时在线判断迭代停止、系统吞吐量受限、大量判决电路影响核心译码电路的低功耗和实时性等问题。考虑上述问题,以因子图模型为基础,针对空间数据系统咨询委员会(Consultative Committee for Space Data Systems,CCSDS)标准深空通信码型,将校验节点归一化满足概率进化图案与LDPC译码器状态紧密耦合,给出可实时在线判断迭代停止的最优停止准则,实现高性能、低复杂度的停止准则译码算法设计。当优先考虑高吞吐量时,误码率(Bit Error Rate,BER)性能退化0.13 dB,中低信噪比平均迭代次数(Average Number of Iteration,ANI)降低50%以上;当优先考虑纠错性能时,BER性能仅退化0.02 dB,同时大幅降低ANI。该译码算法为高效低复杂度LDPC译码器设计提供有效解决方案。展开更多
围长较大的短码长准循环(QC)低密度奇偶校验(LDPC)码的显式构造对于QC-LDPC短码的理论研究与工程应用具有重要意义。首先提出一种基于成对策略的贪婪搜索算法,并根据此算法在列重J为4时的经验结果,归纳总结出一种具有双序列反序特征的...围长较大的短码长准循环(QC)低密度奇偶校验(LDPC)码的显式构造对于QC-LDPC短码的理论研究与工程应用具有重要意义。首先提出一种基于成对策略的贪婪搜索算法,并根据此算法在列重J为4时的经验结果,归纳总结出一种具有双序列反序特征的指数矩阵。随后证明了该指数矩阵对于任意行重L均对应于围长为8的QC-LDPC码。与现有的典型显式构造方法即最大公约数(GCD)方法相比,新QC-LDPC码提供的码长显著降低。最后,将指数矩阵的拆分拼接和掩膜处理技巧与新QC-LDPC码结合起来,设计出了译码性能在高信噪比区超过5G NR LDPC码的合成码。展开更多
光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性...光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性,文章研究LDPC码的优化设计方法。先深入探讨LDPC码的基本原理及其在光纤通信中的应用,接着提出一种基于密度进化和有限字长效应分析的LDPC码优化方法,并通过光学特性仿真OptSim工具进行了验证。实验结果表明,优化后的LDPC码在不同码长下的误码率均取得了显著降低,特别是在长码字情况下,其纠错性能显著提升。展开更多
基金Supported by the National Natural Science Foundation of China (61205116)
文摘The complexity/performance balanced decoder for low-density parity-check （LDPC） codes is preferred in practical wireless communication systems. A low complexity LDPC decoder for the Consultative Committee for Space Data Systems （CCSDS） standard is achieved in DSP. An ap- proximate decoding algorithm, normalized rain-sum algorithm, is used in the implementation for its low amounts of computation. To reduce the performance loss caused by the approximation, the pa- rameters of the normalized min-sum algorithm are determined by calculating and finding the mini- mum value of thresholds through density evolution. The minimum value which indicates the best per- formance of the decoding algorithm is corresponding with the optimized parameters. In implementa- tion, the memory cost is saved by decomposing the parity-check matrix into submatrices to store and the computation of passing message in decoding is accelerated by using the intrinsic function of DSP. The performance of the decoder with optimized factors is simulated and compared with the ideal BP decoder. The result shows they have about the same performance.
基金supported in part by the National Natural Science Foundation of China(NSFC)under Grant 61931015the Peng Cheng Laboratory under Grant PCL2021A10+1 种基金the Science,Technology and Innovation Commission of Shenzhen Municipality(No.JSGG20201103095805015)sponsored by Tsinghua University-Yunnan Mobile Digital TV Company Ltd.,Joint Research Center(JCICBN)。
文摘As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.
文摘军事卫星通信由于需满足信息实时性、传输速率高、通信容量大以及符合星间链路信道的时变特性等要求,通常采用高编码增益、高吞吐量的信道编码方案。低密度奇偶校验(Low-Density Parity-Check,LDPC)码由于具备接近Shannon极限的优异纠错性能和可并行计算的特性成为卫星通信主导信道编码标准之一。目前卫星通信接收机的译码器模块设计仍存在诸如无法实时在线判断迭代停止、系统吞吐量受限、大量判决电路影响核心译码电路的低功耗和实时性等问题。考虑上述问题,以因子图模型为基础,针对空间数据系统咨询委员会(Consultative Committee for Space Data Systems,CCSDS)标准深空通信码型,将校验节点归一化满足概率进化图案与LDPC译码器状态紧密耦合,给出可实时在线判断迭代停止的最优停止准则,实现高性能、低复杂度的停止准则译码算法设计。当优先考虑高吞吐量时,误码率(Bit Error Rate,BER)性能退化0.13 dB,中低信噪比平均迭代次数(Average Number of Iteration,ANI)降低50%以上;当优先考虑纠错性能时,BER性能仅退化0.02 dB,同时大幅降低ANI。该译码算法为高效低复杂度LDPC译码器设计提供有效解决方案。
文摘围长较大的短码长准循环(QC)低密度奇偶校验(LDPC)码的显式构造对于QC-LDPC短码的理论研究与工程应用具有重要意义。首先提出一种基于成对策略的贪婪搜索算法,并根据此算法在列重J为4时的经验结果,归纳总结出一种具有双序列反序特征的指数矩阵。随后证明了该指数矩阵对于任意行重L均对应于围长为8的QC-LDPC码。与现有的典型显式构造方法即最大公约数(GCD)方法相比,新QC-LDPC码提供的码长显著降低。最后,将指数矩阵的拆分拼接和掩膜处理技巧与新QC-LDPC码结合起来,设计出了译码性能在高信噪比区超过5G NR LDPC码的合成码。
文摘光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性,文章研究LDPC码的优化设计方法。先深入探讨LDPC码的基本原理及其在光纤通信中的应用,接着提出一种基于密度进化和有限字长效应分析的LDPC码优化方法,并通过光学特性仿真OptSim工具进行了验证。实验结果表明,优化后的LDPC码在不同码长下的误码率均取得了显著降低,特别是在长码字情况下,其纠错性能显著提升。
