共查询到19条相似文献,搜索用时 312 毫秒
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在不改变译码性能的条件下,为了加快最大后验概率(Maximum A Posteriori Probability,MAP)译码器状态信息更新的速度和降低算法的复杂度,提出了一种用于Turbo码的MAP译码器的免归一化处理算法.算法采用二进制补码加法器和减法器将MAP译码过程中的状态信息投影到一个归一化圆上,当状态信息更新时所有的状态信息在归一化圆上移动,通过保持归一化圆上状态信息的正确关系来计算似然比.归一化过程中不用搜索或估计状态信息的最大值,通过简化状态信息归一化过程加速了MAP译码器的状态信息更新并降低了复杂度.所提算法在与传统算法译码性能相同的情况下,可以降低36.2%的计算复杂度和17.4%的关键路径延迟,达到MAP译码器实现中的高速、低复杂度目标. 相似文献
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球形译码算法的检测性能最接近最大似然检测算法,但其计算复杂度仍然较高。为了在计算复杂度和系统性能之间取得良好折中,在研究标准球形译码的基础上,提出一种新的球形译码改进算法。新算法由快速球形译码与基于MMSE准则的SQRD算法构成。该算法在高信噪比时采用SQRD算法,低信噪比时采用KSDA算法。仿真结果表明,该算法在降低球形译码算法复杂度的同时获得了较好的系统性能。 相似文献
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一种新的LDPC译码算法 总被引:2,自引:0,他引:2
由于LDPC码的优良性能,因此在信息可靠传输中有良好的应用前景。本文提出了一种将BP算法和基于列表的SIHO(软输入硬输出)算法相结合的译码算法,通过与BP、MLD算法的误码率性能和译码复杂度比较,本算法复杂度比MLD有明显降低,而在性能上优于BP算法并接近MLD译码算法。 相似文献
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本文提出一种在形式上类似于卷积码的序列译码的一般线性分组码的软判决伪序列译码算法,利用广义限译码原理及二元有向树的性质与分枝限搜索技术,降低了译码复杂性,其设备复杂度小于Chase译码器,模拟结果表明,该算法的误码输出性能接近维持比较最大似然译码,好于ChaseⅡ算法,且译码速度与ChaseⅡ算法接近。 相似文献
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The maximum a posterioriprobability (MAP) algorithm is a trellis-based MAP decoding algorithm. It is the heart of turbo (or iterative) decoding that achieves an error performance near the Shannon limit. Unfortunately, the implementation of this algorithm requires large computation and storage. Furthermore, its forward and backward recursions result in a long decoding delay. For practical applications, this decoding algorithm must be simplifled and its decoding complexity and delay must be reduced. In this paper, the MAP algorithm and its variation's, such as log-MAP and max-log-MAP algorithms, are first applied to sectionalized trellises for linear block codes and carried out as two-stage decodings. Using the structural properties of properly sectionalized trellises, the decoding complexity and delay of the MAP algorithms can be reduced. Computation-wise optimum sectionalizations of a trellis for MAP algorithms are investigated. Also presented in this paper are bidirectional and parallel MAP decodings 相似文献
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The maximum a posterior probability (MAP) algorithm has been widely used in Turbo decoding for its outstanding performance. However, it is very challenging to design high-speed MAP decoders because of inherent recursive computations. This paper presents two novel high-speed recursion architectures for MAP-based Turbo decoders. Algorithmic transformation, approximation, and architectural optimization are incorporated in the proposed designs to reduce the critical path. Simulations show that neither of the proposed designs has observable decoding performance loss compared to the true MAP algorithm when applied in Turbo decoding. Synthesis results show that the proposed Radix-2 recursion architecture can achieve comparable processing speed to that of the state-of-the-art recursion (Radix-4) architecture with significantly lower complexity while the proposed Radix-4 architecture is 32% faster than the best existing design 相似文献
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A Modified max-log-MAP Decoding Algorithm for Turbo Decoding 总被引:1,自引:0,他引:1
1 IntroductionTheadventofTurbocode presentedbyBERROUCetal.in 1 993isthemilestoneinthehistoryofinformationtheory[1 ] .Turbocode,whichisanewclassofconcatenatedcodes,hasbeenstud iedbymanyacademiciansallovertheworldbecauseofits powerfulerrorcorrectioncapability[1 0… 相似文献
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We present a soft decoding algorithm for convolutional codes that simultaneously yields soft-sequence output, i.e., list sequence (LS) decoding, and soft-symbol output. The max-log list algorithm (MLLA) introduced in this paper provides near-optimum soft-symbol output equal to that of the max-log maximum a posteriori (MAP) probability algorithm. Simultaneously, the algorithm produces an ordered list containing LS-MAP estimates. The MLLA exists in an optimum and a suboptimum version that are different in that the optimum version produces optimum LS-MAP decoding for arbitrary list lengths, while the suboptimum low-complexity version only provides the MAP, the second-order MAP, and the third-order MAP sequence estimates. For lists with more than three elements, MAP decoding is not guaranteed, but the LS decoding is close to the optimal. It is demonstrated that the suboptimum/optimum MLLA can be used to obtain the combination of soft-symbol and soft-sequence outputs at lower complexity than a previously published algorithm. Furthermore, the suboptimum MLLA is well suited for operation in an iterative list (turbo) decoder, since it is obtained by only minor modifications of the well-known Max-Log-MAP algorithm frequently used for decoding of the component codes of turbo codes. Another potential area of application for the suboptimum/optimum MLLA is joint source-channel LS decoding. Estimates of complexity and memory use, as well as performance evaluations of the suboptimum/optimum MLLA, are provided in this paper. 相似文献
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Jun Lee Jaejin Lee 《Electronics letters》2001,37(11):698-700
A modified maximum a posteriori (MMAP) decoding algorithm that uses two extrinsic information values as the thresholds to determine the log-likelihood ratio, forward recursion probability and backward recursion probability is proposed. The MMAP requires less decoding time and complexity than an MAP decoder. Each probability of the proposed algorithm is derived and compared to that obtained using the MAP algorithm 相似文献
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A scheme is proposed to decode a tail-biting convolutional code based on its Tanner graph, which is traditionally done using a forward-backward MAP algorithm. Therefore, decoding may be performed using a standard sum-product algorithm. With respect to decoding based on trellis, all variables in a Tanner graph are binary, which may lead to complexity reduction. A min-sum algorithm is used to decrease the analogue circuit complexity. Simulation shows there is no significant degradation compared with more complex traditional methods 相似文献
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研究了空时分块编码的OFDM(正交频分复用)系统,对系统进行了Turbo均衡,并讨论了此时系统的译码算法和均衡算法。系统信道编码采用Turbo码,通过对BCJR(Bahl,Cocke,Jelinek,Raviv)算法的简单修改得到SISO(单输入单输出)MAP(最大后验概率)译码算法;均衡器采用SISOMMSE(最小均方差)Turbo均衡算法,并利用OFDM系统的循环前缀特性进一步降低算法复杂度。通过仿真对系统性能进行了比较分析,仿真结果表明,采用迭代均衡的空时分块编码OFDM系统性能要明显优于未空时编码和未迭代均衡的OFDM系统。 相似文献