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RESEARCH ON A SOFT-DECISION ITERATIVE DECODING OF A LINEAR BLOCK CODE

线性分组码软决策迭代译码研究

基本信息

批准号：
06650416
负责人：
KASAMI Tadao
金额：
$ 1.28万
依托单位：
Nara Institute of Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In this research, we investigate the following two types of soft-decision suboptimum decoding of a linear block code.(a) Generalized closest coset decoding for a decomposable code : For a code C of length n, C is said to be decomposable if C is the direct sum of C_1 and C_2 of length n. For this type of decomposable codes, we propose a new suboptimum closest coset decoding scheme shown below. Let C'_2 be a supercode of C_2 which is independent from C_1. The following is a kind of closest coset decoding of C.Let z be the received unquantized n-tuple. (1) Decode z into a codeword in C_1 + C'_2 by maximum likelihood decoding. Let u + v be the decoded codeword in C_1 + C'_2, where u*C_1 and V*C'_2. (2) Decode z into a codeword in C_2 + {u}, a translate of C_2, by maximum likelihood decoding. Let u+v denote the decoded codeword, which is the output of the overall decoding. This suboptimum decoding scheme is a generalization of the multi-stage decoding scheme for multi-level modulation codes … More and the closest coset decoding scheme for codes with the |u|u+v|-structure proposed by Hemmati.We investigate the evaluation method of the block error probability of a decomposable block code for the above decoding scheme over an AWGN channel. For some specific example codes, we evaluate the block error probability and the decoding complexity.(b) Iterative decoding : Consider the following iterative decoding scheme : First generate an initial candidate codeword by a relatively less complex decoding a algorithm, such as a hard-decision algebraic decoding. Then iterate that we find more likely codeword around the current candidate codeword by searching by using a minimum weight subtrellis diagram around the current candidate codeword, until we can't find more likely codeword, neither the candidate codeword pass a test of optimality.For this type of iterative decoding, we derive the least stringent sufficient condition that the available information on the code is restricted to (i) the minimum weight and a few small weights and (ii) for a given positive integer h, h or fewer already generated candidate codewords. We also derive a sufficient condition on the optimality under the same assumption as above, except that the condition (i) is changed to (i') complete knowledge of the weight profile of a code is known. We evaluate the average reduction of number of decoding iterations for some Reed-Muller codes over an AWGN channel.We also present a new soft-decision iterative decoding algorithm based on searching by using a minimum weight subtrellis diagram. We show the block error probablity and the decoding complexity for some Reed-Muller codes over an AWGN channel for the proposed decoding. Less

在这项研究中，我们研究了以下两种类型的软判决次优解码的线性分组码。(a)可分解码的广义最近陪集译码：对于长度为n的码C，如果C是长度为n的C_1和C_2的直和，则称C是可分解的。对于这种类型的可分解码，我们提出了一个新的次优最近陪集解码方案如下所示。设C ′_2是C_2的一个独立于C_1的超码。下面是C的一种最近陪集解码。令z是接收到的未量化的n元组。(1)通过最大似然解码将z解码为C_1 + C '_2中的码字。设u + v为C_1 + C ′_2中的解码码字，其中u*C_1和V* C ′_2。(2)通过最大似然解码将z解码为C_2 + {u}中的码字，C_2 + {u}是C_2的平移。令u+v表示解码的码字，其是整个解码的输出。这种次优译码方案是多级调制码多级译码方案的推广 ...更多信息以及用于具有|u| u+v|- 结构，研究了在AWGN信道下，可分解分组码在上述译码方案下的误块概率的估计方法。对于一些具体的示例码，我们评估了块错误概率和解码复杂度。(b)迭代解码：考虑以下迭代解码方案：首先通过相对较不复杂的解码算法（诸如硬判决代数解码）来生成初始候选码字。然后通过使用当前候选码字周围的最小权重子网格图进行搜索，在当前候选码字周围找到更可能的码字，直到不能找到更可能的码字，候选码字也不能通过最优性测试。对于这种类型的迭代解码，我们推导出最不严格的充分条件，即关于码的可用信息被限制为（i）最小权重和几个小权重，以及（ii）对于给定的正整数h，h或更少的已经生成的候选码字。我们还在与上述相同的假设下导出了关于最优性的充分条件，不同之处在于条件（i）被改变为（i '）码的重量分布的完全知识是已知的。在AWGN信道下，我们计算了几种Reed-Muller码的译码迭代次数的平均减少量，并提出了一种新的基于最小权值子格图搜索的软判决迭代译码算法。我们给出了在AWGN信道上的一些Reed-Muller码的误块概率和译码复杂度。少