共查询到17条相似文献,搜索用时 183 毫秒
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软判决译码中软信息的提取 总被引:1,自引:0,他引:1
本文基于单载波和多载波传输的等效基带模型的衰落信道,采用比特交织的编码调制(BICM)系统,研究了软判决译码所需的软信息的提取。通过仿真说明,反馈信道噪声信息的结合解调与译码的迭代译码方法具有一定的鲁棒性。 相似文献
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在基于“信道容量规则”的多级编码系统中采用交织技术与迭代多级译码相结合的方法 ,进一步提高其在Rayleigh衰落信道中的系统性能 相似文献
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主要研究卫星通信协议IESS 309协议中的系统卷积码的编码及其序列译码的计算机模拟。用C语言实现了码率为1/2的36位的系统卷积码的编码,然后模拟高斯噪声信道生成一个Fano度量表,最后用Fano算法实现该卷积码的软判决序列译码,并进行了性能分析,为以后的工程应用打下一个良好的基础。 相似文献
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一种新的π/4DQPSK解调译码方案 总被引:1,自引:0,他引:1
本文提出了一种新的π/4DQPSK解调译码方案.该方案利用非冗余纠错差分解调的硬判决信息对Viterbi软判决译码时的量度加权,从而改变了传统的差分解调结合软判决译码的量度值,使差分解调软输出的信噪比得到改善,提高了Viterbi软判决译码的性能.计算机仿真表明,相对于传统的差分解调结合软判决译码,该算法在误比特率BER为10-5时在AWGN信道中有1.4dB的性能改善,在Rician信道中同样有显著的性能改善.这使得在普遍采用差分解调软判决译码的卫星通信系统中系统容量和通信质量都得到显著改善. 相似文献
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The article first presents the formulation for computing the optimum soft decision metrics for decoding of convolutional codes on fading channels and then demonstrate the performance gains achieved in using the optimum soft decision metrics. The optimum soft decision metrics use channel state information to account for signal strength variations due to fading. The formulation for computing the optimum soft decision metrics is given for the general case in which the statistics of the additive noise on the channel is nonstationary. However, the formulation is applied to a more simple case in which the noise is assumed to be stationary. The results indicate that at moderate signal-to-noise ratios, the 2 dB advantage usually claimed for soft decision decoding over hard decision decoding on Gaussian channels is achievable on fading channel, with the rate 3/4 code used, if the channel state information is incorporated in the soft decision metrics 相似文献
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本文研究多带正交频分复用瑞利衰落信道中,空时网格编码发射天线间空间相关性的分集性能.空时网格编码将单个输出的编码符号转换成多个编码符号,并通过多个发射天线传输,在接收端,Viterbi优化软判决算法用于译码.我们分析了MB-OFDM系统在quasi-static和interleaved两种信道中相关空间衰落对误码率的影响.在空间相关性较小时,分集阶数能得到保持;而在空间相关性较大时,interleaved信道能保持分集阶数,quasi-static信道的分集阶数将减小.空时编码总体上对空间相关性表现出鲁棒性. 相似文献
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针对衰减信道卷积码的译码,给出了当信道附加噪声非固定时,计算最优软判决度量的表达式。仿真结果表明,在适当的信噪比条件下,采用该方法比硬判决的信噪比提高2dB。 相似文献
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基于8PSK的MLC-STBC在瑞利衰落信道中的性能 总被引:1,自引:0,他引:1
文章提出了在瑞利信道中,8PSK调制模式下多级编码空时分组编码级联的MLC-STBC方案,并在系统码率为2.032bit/s、发射天线为2、接收天线数目为1的条件下,分别对多级编码和MLC-STBC级联编码进行了仿真。仿真结果表明,基于8PSK,在瑞利衰落下利用旋转距离度量规则选择分量码码率的MLC-STBC系统,能获得比较理想的系统增益。 相似文献
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本文提出了在移动衰落信道中设计多级编码(MLC)方案的一种非欧度量:"信道容量规则"+"映射规则".在AWGN信道中为:"信道容量规则"+"UP(Ungerboeck Partitioning) 规则";在Rayleigh衰落信道中为:"信道容量规则"+"BP(Block Partitioning)规则".并在此理论指导下,选用不同码长的BCH码作为MLC系统中各级分量码,通过计算机模拟,比较了在AWGN和Rayleigh衰落信道中,采用8ASK调制方式、多级译码(MSD)、三种不同映射方法下的三级MLC方案的性能. 相似文献
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It is shown that a methodology based on hidden Markov models is applicable to the modeling of slowly varying Rayleigh fading channels with additive Gaussian noise and soft decision outputs. The fading is considered to be frequency nonselective, and ideal demodulation is considered throughout. To prove the validity of robustness of the modeling technique, various results that show good agreement between the simulated channels and the models found are presented. Two soft decision statistical distributions, namely, the soft burst and soft burst interval distributions, are defined and compared. To illustrate the accuracy of the models obtained, the simulation and model outputs are compared for a convolutional encoder with Viterbi decoding and various degrees of interleaving 相似文献
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Performance of robust soft decoding metrics is examined for use in convolutional coded asynchronous fast frequency-hop spread-spectrum multiple-access networks using binary frequency-shift keying under Rayleigh fading channels. For comparison, maximum-likelihood metrics based on a Gaussian approximation are derived. Significant gains are observed compared to hard decision decoding by using appropriate soft metrics. 相似文献