共查询到20条相似文献,搜索用时 31 毫秒
1.
Vidhyacharan Bhaskar Author Vitae Laurie L. Joiner Author Vitae 《Computers & Electrical Engineering》2005,31(3):217-240
This paper presents a method of code rate adaptation using punctured convolutional codes for direct sequence spread spectrum communication systems over slowly fading channels. A blind channel estimation technique is used to estimate the nature of the multi-user channel at the detector (before the decoder). The path gains obtained from the channel estimation technique are used to adapt the code rates. Punctured codes derived from a specific rate 1/2 (M = 4) mother code are used to provide error protection corresponding to the actual channel state. The upper and lower bounds on the bit error probability and the upper bound on the error event probability are derived for hard-decision and soft-decision decoding over Rayleigh and Rician fading channels. The throughput gains obtained using the adaptive scheme and the performances of the punctured codes are studied. 相似文献
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介绍了LTE系统中的咬尾卷积编码器,分析了该编码器的增益,在众多译码算法的基础上研究咬尾卷积码的几种译码算法,通过MATLAB对这几种译码算法在不同信道环境、不同长度数据块的情况下进行性能仿真,并对仿真结果进行分析。从性能和复杂度这两个角度考虑, 两步维特比算法较适合作为LTE通信系统中咬尾卷积码的译码方法。 相似文献
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基于FPGA的串行维特比译码的实现 总被引:7,自引:0,他引:7
维特比算法是一种卷积码译码算法。随着卷积码约束度的增加,并行维特比译码所需的硬件资源呈指数增长,限制其硬件实现。该文讨论了一种申行译码结构的FPGA实现方案。这种申行结构适合长约束度的卷积码译码,能在性能不下降的前提下有效地节省资源。 相似文献
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Shu-Tao Xia 《计算机科学技术学报》2006,21(6):950-951
In this paper, we study the stopping sets, stopping distance and stopping redundancy for binary linear codes. Stopping redundancy is a new concept proposed by Schwartz and Vardy recently for evaluating the performance of a linear code under iterative decoding over a binary erasure channel (BEC). Since the exact value of stopping redundancy is difficult to obtain in general, good lower and upper bounds are important. We obtain a new general upper bound on the stopping redundancy of binary linear codes which improves the corresponding results of Schwartz and Vardy. 相似文献
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为解决信道译码在高吞吐量通信系统中的瓶颈问题,通过对CUDA并行计算的了解和对维特比译码并行实现的探索,为卷积码提出了一种基于CUDA的截断重叠维特比译码器。算法通过截断式的子网格图相互重叠的方式,并行执行独立的正向度量计算和回溯过程。实验结果表明,在保证了译码算法误码率性能的同时,获得了良好的吞吐量提升表现,相比现有的实现方式有1.3~3.5倍的提升,降低了硬件开销,能够有效运用于实际高吞吐量通信系统中。 相似文献
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Viterbi译码算法是最大似然译码。论文所研究的改进Viterbi算法,不但保持了原有Viterbi算法的特性,而且在减少译码路径的情况下,能较好地解决突发错误信道中,原Viterbi译码算法则性能急剧下降的问题。通过在编码信道模型上的仿真表明,已知正确的约束位越多,分布的越密,则提高的性能越明显。 相似文献
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An upper bound on the error probability (first error event) of product convolutional codes over a memoryless binary symmetric channel, and the resulting error exponent are derived. The error exponent is estimated for two decoding procedures. It is shown that, for both decoding methods, the error probability exponentially decreasing with the constraint length of product convolutional codes can be attained with nonexponentially increasing decoding complexity. Both estimated error exponents are similar to those for woven convolutional codes with outer and inner warp. 相似文献
9.
基于改进Walsh-Hadamard变换的删除卷积码盲解码算法* 总被引:2,自引:0,他引:2
针对高误码率情况下,删除卷积码的盲解码问题,提出了一种删除卷积码的盲解码算法。通过采用改进的沃尔什-哈达马变换(Walsh-Hadamard translate,WHT),识别出删除卷积码的高维校验矩阵;再基于源卷积码的生成矩阵与校验矩阵间的约束关系,求出了源卷积码的最佳生成多项式和删除模式,并提出了码字同步的方法,最终按识别出来的参数构建盲解码模型,实现了删除卷积码的盲解码。仿真结果表明,在误码率低于0.01的情况下,该算法的译码正确率能达到93%。 相似文献
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In this paper, by introducing orthogonal space-time coding scheme, the multiuser CDMA systems with different space time codes
are given, and corresponding system performance is investigated over Rayleigh fading channel. A low-complexity multiuser receiver
scheme is developed for space-time coded CDMA systems. The scheme can make full use of the complex orthogonality of space-time
coding to simplify the high decoding complexity of the existing scheme. Compared to the existing scheme with exponential decoding
complexity, it has linear decoding complexity. Based on the performance analysis and mathematical calculation, average bit
error rate (BER) of the system is derived in detail, and tight closed-form approximation expressions of BER are attained.
Simulation results on average BER are in agreement with the theory analysis. The results show that the proposed scheme can
achieve almost the same performance as the existing scheme. Moreover, on the condition of same system throughput and concatenation
of channel code, the given full-rate space-time coded CDMA system has lower BER than the full-diversity space-time coded CDMA
systems. 相似文献
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A. Wachter V. R. Sidorenko M. Bossert V. V. Zyablov 《Problems of Information Transmission》2011,47(2):117-129
(Partial) unit memory ((P)UM) codes provide a powerful possibility to construct convolutional codes based on block codes in
order to achieve a high decoding performance. In this contribution, a construction based on Gabidulin codes is considered.
This construction requires a modified rank metric, the so-called sum rank metric. For the sum rank metric, the free rank distance, extended row rank distance, and its slope are defined analogous to the extended row distance in the Hamming metric. Upper bounds for the free rank distance and slope
of (P)UM codes in the sum rank metric are derived, and an explicit construction of (P)UM codes based on Gabidulin codes is
given. 相似文献
14.
张红 《计算机与数字工程》2009,37(12):42-46
维特比算法是卷积码的一种最大似然译码。维特比译码器中的存储部分,包括幸存路径的存储和路径度量的存储,其结构的选择对其占用硬件资源影响也不同。文章采用同址存储的方法来实现约束度为9的(2,1,9)维特比译码器中的幸存路径的存储,该方法相对于传统的寄存器存储、回溯法来讲,具有资源占用少、译码延时小等特点。同址存储是存储体的一种实现方法,较之别的存储方法,其优点是需要的存储单元较少。 相似文献
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一种卷积码维特比译码算法的软件实现 总被引:3,自引:0,他引:3
提出了数字通信系统中一种卷积码译码的软件实现方案,该方案应用软件技术实现了卷积码维特比译码器功能,在程序实现中充分利用了卷积码的特性,运用蝶形运算,周期性的回溯以得到译码输出。在程序设计上采用了一些宏定义等处理方法,可以提升运算速度,是一种软件方法的前向纠错编码技术。 相似文献
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基于卷积码的盲音频水印算法研究 总被引:1,自引:0,他引:1
提出了一种基于提升小波和卷积码的盲音频水印算法。原始音频信号经过提升小波变换后,选取中低频小波系数进行自适应水印嵌入。水印在嵌入前经过卷积编码和交织预处理,以提高水印系统的抗干扰能力。为了增强算法的鲁棒性,水印提取时采用了软判决Viterbi译码。实验结果表明,该水印算法具有较好的性能。 相似文献
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针对现有能量捕获技术存在能量来源不稳定、储能设备容量有限等特点,提出了一种基于超级电容和电池的混合储能结构,并建模分析其相应的通信信道容量性能。首先,针对点对点能量捕获无线通信系统,建立基于混合能量存储结构的通信信道模型。其次,根据能量捕获的随机特性,假设能量到达过程符合伯努利随机过程,提出了一种近似最优能量分配策略,推导出系统平均吞吐量的上、下界限及其常数差值,并进一步求得系统近似信道容量。最后,通过实验验证了在捕获能量小于和大于超级电容储能容量两种情形下,系统信道容量上、下界的恒定差值分别为1.77bps/Hz和2.49bps/Hz;同时,相比传统节点采用电池作为单一储能结构,混合能量存储结构能够有效提高系统的能量利用率,增大系统的信道容量,当超级电容储能容量与电池储能容量的比例为12时,信道容量的上界 可提升到70%。 相似文献
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提出了一种依据802.11n规范的单流基带收发器系统算法模型,系统收发模型包括内接收机和外接收机,内接收机基于短训练序列完成帧同步和频率同步的联合估计与频率补偿,基于长训练序列完成符号细同步,采用LS方法实现信道估计,频率/相位联合跟踪和补偿确保内接收机的接收信号质量。外接收机分别采用Viterbi和LDPC完成信道译码设计,选择最小和的置信度传递算法进行LDPC设计,对LPDC和Viterbi的译码性能进行比较,在IEEE WLAN TGN信道条件下,对系统模型的误码率和误帧率进行仿真测试,结果表明,该基带系统算法达到系统设计指标需求。 相似文献