共查询到18条相似文献,搜索用时 78 毫秒
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为满足未来移动通信对高数据传输速率迅速增长的需求,本文提出了高频谱效率的联合编码调制分集(Joint Coding Modulation Diversity,JCMD)的多输入多输出(Multiple-Input Multiple-Output,MIMO)方案.从全局的角度,该方案通过空时分量交织器和旋转调制对Turbo编码,正交幅度调制(Quadrature Amplitude Modulation,QAM)和MIMO技术进行联合优化.本文首次证明了JCMD-MIM的可达速率大于等功率分配的BICM-MIMO系统.基于以上理论分析,提出了一种最佳空间分量交织器以及自适应层数选择方案以最大化系统的可达速率.仿真结果表明新方案与传统的BICM-MIMO方案相比可以获得明显的信噪比增益. 相似文献
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LDPC编码调制系统中基于反馈LLR均值的迭代解调/译码算法 总被引:1,自引:0,他引:1
该文针对LDPC码编码的BICM系统,提出一种对LDPC码译码器输出外附信息的计算方法进行改进的迭代解调/译码算法。与传统的解调/译码算法不同在于,该算法对每次BP迭代中译码器输出的各编码比特的外附LLR分别求均值后,再将其作为先验信息反馈给软解调器开始下次的迭代解调/译码。采用该方法可有效地减轻LDPC码在BP迭代过程中某些比特LLR值的振荡现象,从而使得传递给软解调器的外附信息更准确。仿真结果表明,和传统的两种迭代解调/译码算法相比,该算法能进一步提高LDPC编码BICM迭代系统的译码性能,而复杂度并无明显增加。 相似文献
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对于功率受限的加性高斯白噪声(Additive White Gaussian Noise,AWGN)信道,当具有高斯分布的信号作为信道输入时,信息传输性能接近信道容量.为了传输性能接近容量限,本文采用优化的非均匀排布APSK(Amplitude Phase Shift Keying)星座取代传统的多维QAM(Quadrature Amplitude Modulation)调制星座图,利用二进制交换算法(Binary Switching Algorithm,BSA)进行星座图的反馈后哈姆尼克均值优化,设计了一种新型的"4+12F-APSK"非均匀排布的星座映射方案,并与BICM-ID(Bit Interleaved Coded Modulation-Iterative Decoding)解调译码相结合,提出了基于高性能编码调制映射的联合解调译码方法,有效地解决了接近信道容量限的联合解调译码的难题.实验结果表明,在瑞利衰落信道误比特率在10的-5次方量级时,该方法比传统的MSEW(Maximum Squared Euclidean Weight),GRAY,SP(Set Partitioning)三种矩形QAM调制方案的译码性能至少改善0.6dB;在AWGN信道误比特率在10的-3次方量级时,该方法比传统的MSEW和GRAY映射至少改善0.3dB.同时,与其他16APSK映射方案相比,该方法无论是在瑞丽衰落信道还是在AWGN信道条件下,在相同的误比特率量级上,都具有1dB~2dB的译码性能增益,有效地逼近了传输容量限.该方法在移动通信和电视广播通信等资源有限网络中具有广泛的应用前景. 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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为了在不降低频带利用率和功率利用率的情况下以设备的复杂化来换取编码增益,提出了一种将编码和调制方式结合在一起的比特交织编码调制(Bit Interleaved Coded Modulation,BICM)技术。该技术针对网格编码调制(TrellisCoded Modulation,TCM)灵活性差和衰落信道中性能差的缺点,在理想交织时将编码器和调制器分离设计,具有高度的灵活性,并可以得到近似网格编码调制的性能,并且对衰落信道具有很好的鲁棒性。介绍了比特交织编码调制的构成模式、关键技术,包括信道编码、比特交织和调制,给出了BCIM理论分析,并对不同的交织深度、交织方法和高阶调制等进行了性能仿真分析。仿真结果表明比特交织编码调制可以取得良好的误码率性能。 相似文献
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一种适用于BICM-ID系统的迭代载波同步算法 总被引:1,自引:0,他引:1
在比特交织编码调制迭代译码(BICM-ID)系统中,针对低信噪比条件下传统的同步算法对频偏和相差估计精度较低的问题,提出了一种码辅助的迭代载波同步算法。该算法基于最大期望(EM)算法,并在此基础上加以改进,利用译码器输出的软信息,迭代的在载波同步和译码之间相互交换信息,实现同步和译码的联合处理。仿真结果表明,在译码器收敛的允许范围之内,提出的算法能够大幅提高同步参数的估计精度,在迭代次数达到8次时,BICM-ID系统的误比特率性能基本接近理想同步条件下的译码性能。 相似文献
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提出一种基于比特交织编码调制(BICM)的高效编码协作(CC)方案,该方案中协作用户编码比特分为两帧,每一帧都通过BICM调制发送,通过结合比特交织器满足高阶调制星座符号的不同比特经历的衰落独立。一方面,论文分析了该协作方案在不同信道下的成对错误概率,并进一步推导了错误比特概率上界。理论分析以及仿真结果都表明:准静态衰落信道下,基于BICM的高谱效率编码协作方案仍然可以获得完全分集;而快衰落信道下,编码协作没有分集。另一方面,论文针对提出CC方案中映射方式以及交织器的设计进行研究,得出GRAY映射仍然是协作用户采用的最佳映射,且两帧的交织器不同更利于提高性能。 相似文献
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迭代检测技术不仅局限于在传统的级联码系统中的应用,还可用于解决现代数字通信中的许多检测/译码问题。随着Turbo码的出现,人们对迭代译码算法进行深入研究,并提出一些简化译码算法。比特交织编码调制及迭代检测(bit—interleaved coded modulation with iterative decoding,BICMID)是一种高效数据传输系统。比特交织和迭代译码是BICM—ID系统具有卓越性能的关键因素,译码算法的选择不仅影响接收机的性能,也决定了系统的复杂度。文中研究迭代译码算法对BICM—ID系统性能的影响,分析各种译码算法的计算复杂度。仿真结果表明log-APP算法有好的性能同时复杂度也高,简化的译码算法能降低译码器的复杂度,但会带来一定的性能损失;随着信道条件的改善,算法简化带来的性能损失也随之减小。 相似文献
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针对无线光通信脉冲位置调制(PPM)与信道编码的结合应用,提出了一种多级编码调制方案,利用多级编码的多级标签结构,将PPM符号所对应的分组比特分拆到不同子码通道的码字中,同时结合PPM的信号集分割和极大似然检测解调方法,推导了方案的多阶段解调译码算法。在弱湍流大气条件下的仿真分析表明,PPM多级编码调制相对单级编码调制在误码率10-6下获得0.85 dB以上的增益,且可实现对不同重要程度信息段的不等差错保护。在分量码码型给定的条件下,按纠错能力逐级配置分量码并采用所推导的多阶段解调译码,可为系统提供更好差错性能,优于直接的并行译码方法。 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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Zou Xuelan Feng Guangzeng 《电子科学学刊(英文版)》2008,25(1):59-64
Bit-Interleaved Coded Modulation with Iterative Decoding (BICM-ID) is a bandwidth efficient transmission, where the bit error rate is reduced through the iterative information exchange between the inner demapper and the outer decoder. The choice of the symbol mapping is the crucial design parameter. This paper indicates that the Harmonic Mean of the Minimum Squared Euclidean (HMMSE) distance is the best criterion for the mapping design. Based on the design criterion of the HMMSE distance, a new search algorithm to find the optimized labeling maps for BICM-ID system is proposed. Numerical results and performance comparison show that the new labeling search method has a low complexity and outperforms other labeling schemes using other design criterion in BICM-ID system, therefore it is an optimized labeling method. 相似文献
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We present an iterative decoding/demodulation technique for an orthogonal space-time coded continuous-phase modulation (OST-CPM) system. A low-complexity soft input and soft output (SISO) demodulator is developed based on the bidirectional soft output Viterbi algorithm (BSOVA) for the multiple antennas CPM systems. By taking advantage of the orthogonal structure, the complexity of extrinsic information extraction can be significantly reduced at each iteration.Shengli Fu received the B.S. and M.S. degree in telecommunication engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. In 2000, he enrolled at the Wright State University, Dayton, OH, where he received the M.S. degree in Computer Engineering. He currently pursues his Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Delaware.His research interests include information and coding theory, MIMO wireless communication systems, and acoustic and visual signal processing.Genyuan Wang received B.Sc and MS. degrees in Mathematics from the Shanxi Normal University, Xian, China, in 1985 and 1988, respectively, and his Ph.D. degree in Electrical Engineering from Xidian University, Xian China, in 1998.From July, 1988 to September 1994, he worked at Shanxi Normal University as an Assistant Professor and then an Associate Professor. From September 1994 to May 1998, he worked at Xidian University as a research assistant. Currently, he is Post-Doctoral Fellow at Department of Electrical and Computer Engineering, University of Delaware. His research interests are radar imaging and radar signal processing, adaptive filter, OFDM system, channel equalization and space-time coding.Xiang-Gen Xia (M97,S00) received his B.S. degree in mathematics from Nanjing Normal University, Nanjing, China, and his M.S. degree in mathematics from Nankai University, Tianjin, China, and his Ph.D. degree in Electrical Engineering from the University of Southern California, Los Angeles, in 1983, 1986, and 1992, respectively.He was a Senior/Research Staff Member at Hughes Research Laboratories, Malibu, California, during 1995--1996. In September 1996, he joined the Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, where he is a Professor. He was a Visiting Professor at the Chinese University of Hong Kong during 2002–2003. Before 1995, he held visiting positions in a few institutions. His current research interests include space-time coding, MIMO and OFDM systems, and SAR and ISAR imaging. Dr. Xia has over 100 refereed journal articles published, and 6 U.S. patents awarded. He is the author of the book Modulated Coding for Intersymbol Interference Channels (New York, Marcel Dekker, 2000).Dr. Xia received the National Science Foundation (NSF) Faculty Early Career Development (CAREER) Program Award in 1997, the Office of Naval Research (ONR) Young Investigator Award in 1998, and the Outstanding Overseas Young Investigator Award from the National Nature Science Foundation of China in 2001. He also received the Outstanding Junior Faculty Award of the Engineering School of the University of Delaware in 2001. He is currently an Associate Editor of the IEEE Transactions on Mobile Computing, the IEEE Signal Processing Letters, the IEEE Transactions on Signal Processing, the International Journal of Signal Processing, and the EURASIP Journal of Applied Signal Processing. He was a guest editor of Space-Time Coding and Its Applications in the EURASIP Journal of Applied Signal Processing in 2002. He is also a Member of the Signal Processing for Communications Technical Committee and the Sensor Array and Multichannel (SAM) Technical Committee in the IEEE Signal Processing Society. 相似文献
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采用预判决信息的LDPC码编码调制方案性能研究 总被引:1,自引:0,他引:1
低密度奇偶校验(LDPC)码是Turbo码以外另一种性能接近香农限的好码.本文将LDPC码与比特交织编码调制(BICM)相结合,首先给出了在不使用传统解调器与译码器之间迭代的情况下8PSK调制方案在AWGN信道和Rayleigh衰落信道中的性能(简称为无迭代方案).然后提出了一种新的接收端解决方案:首先对接收符号进行预判决,判决信息被用来调整解调器,从而在一定程度上弥补了不使用解调器与译码器之间迭代所造成的性能损失,并且相对于无迭代方案接收端复杂度几乎没有变化,但性能却有所提高.这说明原有比特度量产生方法并不是最佳的,该文使用预判决信息的方案给出了一个改善的思路.通过仿真结果可以得到结论:使用本文所提出的方案在AWGN信道和Rayleigh衰落信道中都可以在不增加复杂度的情况下提高性能. 相似文献