We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characterist...We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.展开更多
It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two comp...It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two component decoders, we can gain two soft output values for the received observation of an input bit. It is obvious that two soft output values comprise more sufficient extrinsic information than only one output value obtained in the conventional scheme since different start points of decoding result in different combinations of the a priori information and the input codewords with different symbol orders due to the permutation of an interleaver. Summarizing two soft output values for erery bit before making hard decisions, we can correct more errors due to their complement. Consequently, turbo codes can achieve better error correcting performance than before in this way. Simulation results show that the performance of turbo codes using the novel proposed decoding scheme can get a growing improvement with the increment of SNR in general compared to the conventional scheme. When the bit error probability is 10-5 , the proposed scheme can achieve 0.5 dB asymptotic coding gain or so under the given simulation conditions.展开更多
将二维映射下的软输入软输出解映射MAX-LOG-MAP算法扩展到多维映射比特交织编码调制及迭代译码(BICM-ID)系统,并首次结合多天线系统下的列表球形译码,提出一种简化MD-LSD(multi-dimensional list sphere decoding)算法。新算法大幅降低...将二维映射下的软输入软输出解映射MAX-LOG-MAP算法扩展到多维映射比特交织编码调制及迭代译码(BICM-ID)系统,并首次结合多天线系统下的列表球形译码,提出一种简化MD-LSD(multi-dimensional list sphere decoding)算法。新算法大幅降低了多维解映射的计算复杂度。仿真结果表明,列表长度满足一定范围时,采用简化MD-LSD算法解映射算法的性能损失可以忽略。展开更多
低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统...低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统中,由于GFDM子载波间非正交特性以及低轨卫星信道存在时间-频率双选择性,导致数据符号受到严重的子载波间干扰和子符号间干扰,传统信道估计算法难以实现可靠的数据传输。现有的基于离散导频的迭代信道估计和信号检测算法(Iterative Channel Estimation and Signal Detection Algorithm Based on Discrete Pilots,ICESD-DP)虽然提高了在双选信道下信道估计的准确性,但需要付出高昂的计算成本。为解决上述问题,提出了一种基于判决重构符号的迭代信道估计和干扰消除算法(Iterative Channel Estimation and Interference Cancellation Algorithm Based on Judgment Reconstructed Symbols,ICEIC-JRS),使用经过干扰预处理的导频进行初始信道估计和均衡,在每次迭代中利用Turbo译码器生成的判决重构符号估计数据符号的有效增益和干扰增益,继而对接收符号进行干扰消除,以提高信道估计与符号检测的精度。仿真结果表明,与ICESD-DP相比,ICEIC-JRS在较多迭代次数下表现出更优异的误码率(Bit Error Rate,BER)和均方误差(Mean Square Error,MSE)性能,且ICEIC-JRS的单次迭代复杂度下降了一个数量级,更适用于对运算复杂度有较高要求的低轨卫星通信系统。展开更多
文摘We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.
文摘It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two component decoders, we can gain two soft output values for the received observation of an input bit. It is obvious that two soft output values comprise more sufficient extrinsic information than only one output value obtained in the conventional scheme since different start points of decoding result in different combinations of the a priori information and the input codewords with different symbol orders due to the permutation of an interleaver. Summarizing two soft output values for erery bit before making hard decisions, we can correct more errors due to their complement. Consequently, turbo codes can achieve better error correcting performance than before in this way. Simulation results show that the performance of turbo codes using the novel proposed decoding scheme can get a growing improvement with the increment of SNR in general compared to the conventional scheme. When the bit error probability is 10-5 , the proposed scheme can achieve 0.5 dB asymptotic coding gain or so under the given simulation conditions.
文摘将二维映射下的软输入软输出解映射MAX-LOG-MAP算法扩展到多维映射比特交织编码调制及迭代译码(BICM-ID)系统,并首次结合多天线系统下的列表球形译码,提出一种简化MD-LSD(multi-dimensional list sphere decoding)算法。新算法大幅降低了多维解映射的计算复杂度。仿真结果表明,列表长度满足一定范围时,采用简化MD-LSD算法解映射算法的性能损失可以忽略。
文摘低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统中,由于GFDM子载波间非正交特性以及低轨卫星信道存在时间-频率双选择性,导致数据符号受到严重的子载波间干扰和子符号间干扰,传统信道估计算法难以实现可靠的数据传输。现有的基于离散导频的迭代信道估计和信号检测算法(Iterative Channel Estimation and Signal Detection Algorithm Based on Discrete Pilots,ICESD-DP)虽然提高了在双选信道下信道估计的准确性,但需要付出高昂的计算成本。为解决上述问题,提出了一种基于判决重构符号的迭代信道估计和干扰消除算法(Iterative Channel Estimation and Interference Cancellation Algorithm Based on Judgment Reconstructed Symbols,ICEIC-JRS),使用经过干扰预处理的导频进行初始信道估计和均衡,在每次迭代中利用Turbo译码器生成的判决重构符号估计数据符号的有效增益和干扰增益,继而对接收符号进行干扰消除,以提高信道估计与符号检测的精度。仿真结果表明,与ICESD-DP相比,ICEIC-JRS在较多迭代次数下表现出更优异的误码率(Bit Error Rate,BER)和均方误差(Mean Square Error,MSE)性能,且ICEIC-JRS的单次迭代复杂度下降了一个数量级,更适用于对运算复杂度有较高要求的低轨卫星通信系统。
