有限域上非本原BCH码的对偶包含判定

 循环陪集在经典和量子纠错编码理论中具有非常重要的作用.根据CSS编码定理知,利用经典BCH码构造量子BCH码时需要判断经典BCH码是否包含其对偶码.本文给出了循环陪集的若干重要性质,根据这些性质得到了判断有限域上非本原BCH码是否包含其对偶码的准则.本文给出的判断准则时间复杂度为多项式的,并且该判断准则对本原BCH码也适用.     

分组陪集码的误码特性分析

本文讨论了分组陪集码在最大似然译码与最近陪集译码下的误码特性,这一分析是分别在归一化重量分布和真实距离下做出的,并对其差异进行了比较。本文同时讨论了采用最小距离和最小距离系数进行误码率估计的方法,并指出这些参数可由子码的相应汉明参数得到。     

光通信中基于BCJR的BCH译码算法研究

首先从理论上分析了硬判决译码算法和软判决译码算法的性能然后对BCH(Bose,Ray-Chaudhuri,Hocquenghem)码的网格结构以及BCJR(Bahl,Cocke,Jelinek and Raviv)算法进行了详细地分析及推导。实验结果表明,在光信道环境中,在误比特率为10-5时,当仅提高最小汉明距离码率相同或者仅减小码率最小汉明距离相同时,BCJR算法相对于硬判决译码算法的编码增益分别在之前的编码增益基础上又增加了0.15dB和0.25dB。因此设计级联码方案时,应尽可能选择纠错能力较大的内码。此外也可以采用适当增加内码的冗余度相应减小外码的冗余度的方法,在获得更高的编码增益的同时保证整个系统的带宽利用率不变。     

多载波NOMA安全通信系统稳健性资源分配算法

为提升无线网络频谱利用率和增强信息传输的安全性,针对下行多载波非正交多址接入安全通信系统,提出了一种基于安全和速率最大化的稳健性资源分配算法.首先,设计人工噪声(AN)预编码矢量与合法用户信道正交,消除人工噪声对合法传输的影响.然后,考虑每个用户最小速率约束、基站最大功率约束,基于窃听信道不确定性建立AN预编码、下行数...     

两类厄米特对偶包含的BCH码及其应用

Bose-Chaudhuri-Hocquenghem(BCH)码是一类重要的经典纠错码,可以纠正多个错误且具有高效的编码和译码方法,满足一定结构关系的BCH码可以构造量子纠错码.本文研究了有限域上两类BCH码,基于分圆陪集的结构性质,给出了这两类BCH码满足厄米特对偶包含的条件,通过确定每个分圆陪集所含元素个数,计算出了这两类厄米特对偶包含的BCH码的维数,并利用厄米特构造法,由这两类厄米特对偶包含的BCH码得到了一些参数较好的量子纠错码.     

面向物理层安全的一种打孔极化编码方法

为了解决物理层安全编码中安全性和可靠性之间的矛盾和提高保密速率,该文提出一种基于打孔极化码的安全编码方法。根据信道极化理论,该方法将私密信息位映射到合法者正常接收而窃听者无法译码的特定逻辑信道输入位,保证私密信息可靠且安全传输。然后,通过分析极化码的校验关系树,利用3个参数表征输出节点对私密信息位的影响,再按照影响程度大小确定打孔位置。理论分析与仿真结果表明,该方法保证私密信息传输安全性和可靠性的同时,提高了私密信息传输的有效性。     

一种适合于衰落信道的BCM码的集分割映射方法

在瑞利衰落信道中,对于一个分组调制(Block Coded Modulation)码的构造通常是通过将具有尽可能大最小乘积距离和汉明距离的成分码与Ungerboeck的集分割映射相结合来实现的,但这种集分割映射方法使得构造的BCM码的路径复杂度大大增加,造成了系统性能的下降。文章给出了一种新的集分割映射方法。仿真结果表明,采用这种方法构造出的BCM码在瑞利衰落信道中的性能较前者有很大的改善。     

瑞利衰落信道上的6PSK环码

本文在文献「１０」的基础上，进一步探讨６ＰＳＫ环码在瑞利衰落信道上的误码特性，用分量码重量集合给出了衰落条件下误码概率指数Δ的表达式，并通过例子与相同构造条件下的陪集码进行了比较，证明了在瑞利衰落条件下，环码也优于任何一种构造的陪集码。     

Coherent网络中的纠错码

网络编码对网络中的传输错误或恶意攻击十分敏感,如果网络拓扑和网络码对于网络的收点和发点都是已知的,这种类型的网络称为Coherent网络。在Coherent网络中,网络汉明重量的概念拉近了网络纠错码和传统纠错码之间的距离,传统纠错码的一些理论和方法有望在将来应用于网络纠错码。类似于传统纠错码,极小距离反映了网络纠错码的纠错能力。利用陪集码理论去描述和研究网络纠错码是一个令人感兴趣的研究方向。     

基于分离信源信道码的相关信源在有噪广播信道下的可靠和安全传输

从信息论的角度对相关信源在离散无记忆广播信道下可靠和安全传输的问题进行研究。2个信源经过有噪信道分别到达各自指定的目的节点并被无损恢复,同时还要保证信源信息对于非指定的目的节点要有一定的保密性。采用信源信道分离的随机码策略,得到相关信源在一般广播信道下能够可靠和安全传输的充分条件。当2个信源的公共信息为二者的互信息时,可获得最佳压缩传输效率,并且能够做到信源信息传输的部分绝对保密。当广播信道采用退化信源集或满足more capable广播信道性质时,得到了可靠和安全传输的充分必要条件,此时分离信源信道码为最优码。     

Improved coding techniques for preceded partial-response channels

A coset of a convolutional code may be used to generate a zero-run length limited trellis code for a 1-D partial-response channel. The free squared Euclidean distance, d_free², at the channel output is lower bounded by the free Hamming distance of the convolutional code. The lower bound suggests the use of a convolutional code with maximal free Hamming distance, d_max(R,N), for given rate R and number of decoder states N. In this paper we present cosets of convolutional codes that generate trellis codes with d_free ²>d_max(R,N) for rates 1/5⩽R⩽7/9 and (d _free²=d_max(R,N) for R=13/16,29/32,61/64, The tabulated convolutional codes with R⩽7/9 were not optimized for Hamming distance. Instead, a computer search was used to determine cosets of convolutional codes that exploit the memory of the 1-D channel to increase d_free² at the channel output. The search was limited by only considering cosets with certain structural properties. The R⩾13/16 codes were obtained using a new construction technique for convolutional codes with free Hamming distance 4. Newly developed bounds on the maximum zero-run lengths of cosets were used to ensure a short maximum run length at the 1-D channel output     

Cosets of convolutional codes with short maximum zero-run lengths

Communication systems and storage systems derive symbol synchronization from the received symbol stream. To facilitate symbol synchronization, the channel sequences must have a short maximum zero-run length. One way to achieve this is to use a coset of an (n, k) convolutional code to generate the channel inputs. For k⩽n-2, it is shown that there exist cosets with short maximum zero-run length for any constraint length. Any coset of an (n, n-1) code with high rate and/or large constraint length is shown to have a large maximum zero-run length. A systematic procedure for obtaining cosets with short maximum zero-run length from (n, k) codes is presented, and new cosets with short maximum zero-run length and large minimum Hamming distance are tabulated     

Binary multilevel coset codes with interlevel coding

An improved multilevel coset coding scheme is proposed. By providing interlevel coding between adjacent blocks, the proposed scheme has a multilevel and single-stage coding structure. The coding rate of the proposed scheme can be increased without decreasing the minimum Hamming distance as compared to the traditional scheme.     

光通信中基于脉冲调制的联合编码调制研究

为了研究无线光通信中数字脉冲调制与信道编码的联合编码调制问题,在给出调制时域结构的基础上,采用理论推导和数值仿真相结合的方法,分析了基于二进制线性分组码的开关键控、数字脉冲位置调制和数字脉冲间隔调制系统的差错性能,得出了信道编码纠错能力与调制阶数的结合关系。结果表明,采用开关键控调制的系统,其汉明距离与欧式距离等价,故不存在调制与信道编码参量匹配问题;脉冲位置调制系统在纠错个数大于调制阶数时,可取得较明显的编码调制增益,当纠错个数能被调制阶数整除时,编码和调制达到匹配;由于数字脉冲间隔调制的符号时隙不固定,存在错误传播现象,不宜与差错编码联合使用。所得结果可为无线光通信链路的设计提供参考。     

Euclidean distance for combinations of some Hamming codes and binary CPFSK modulation (Corresp.)

The integration of channel coding and modulation in a communication system to increase the Euclidean distance between modulated signals is analyzed. Systems using binary continuous-phase frequency-shift keying modulation and some block codes, such as Hamming codes and shortened Hamming codes, are considered. It is shown that the minimum Euclidean distance depends on the configuration of the parity-check matrixHof the code. For the examined codes the optimum configurations ofH, which give the maximum values of the minimum Euclidean distance, are determined.     

The capacity of binary channels that use linear codes and decoders

This paper analyzes the performance of concatenated coding systems operating over the binary-symmetric channel (BSC) by examining the loss of capacity resulting from each of the processing steps. The techniques described in this paper allow the separate evaluation of codes and decoders and thus the identification of where loss of capacity occurs. They are, moreover, very useful for the overall design of a communications system, e.g., for evaluating the benefits of inner decoders that produce side information. The first two sections of this paper provide a general technique (based on the coset weight distribution of a binary linear code) for calculating the composite capacity of the code and a BSC in isolation. The later sections examine the composite capacities of binary linear codes, the BSC, and various decoders. The composite capacities of the (8,4) extended Hamming, (24, 12) extended Golay, and (48, 24) quadratic residue codes appear as examples throughout the paper. The calculations in these examples show that, in a concatenated coding system, having an inner decoder provide more information than the maximum-likelihood (ML) estimate to an outer decoder is not a computationally efficient technique, unless generalized minimum-distance decoding of an outer code is extremely easy. Specifically, for the (8,4) extended Hamming and (24, 12) extended Golay inner codes, the gains from using any inner decoder providing side information, instead of a strictly ML inner decoder, are shown to be no greater than 0.77 and 0.34 dB, respectively, for a BSC crossover probability of 0.1 or less, However, if computationally efficient generalized minimum distance decoders for powerful outer codes, e.g., Reed-Solomon codes, become available, they will allow the use of simple inner codes, since both simple and complex inner codes have very similar capacity losses     

Vector coding for partial response channels

A linear technique for combining equalization and coset codes on partial response channels with additive white Gaussian noise is developed. The technique, vector coding, uses a set of transmit filters or `vectors' to partition the channel into an independent set of parallel intersymbol interference (ISI)-free channels for any given finite (or infinite) block length. The optimal transmit vectors for such channel partitioning are shown to be the eigenvectors of the channel covariance matrix for the specified block length, and the gains of the individual channels are the eigenvalues. An optimal bit allocation and energy distribution, are derived for the set of parallel channels, under an accurate extension of the continuous approximation for power in optimal multidimensional signal sets for constellations with unequal signal spacing in different dimensions. Examples are presented that demonstrate performance advantages with respect to zero-forcing decision feedback methods that use the same coset code on the same partial response channel. Only resampling the channel at an optimal rate and assuming no errors in the feedback path will bring the performance of the decision feedback methods up to the level of the vector coded system     

一种基于适应度函数遗传算法的公平交换协议自动生成方法

基于现有协议自动生成方法无法直接用于公平交换协议,我们对Clark Jacob方法进行了扩展,针对公平交换协议的设计空间特征,获得公平性判定模型,模型引入通信信道类型编码,并将主体拥有集合和主体信念集合相分离来完成协议生成过程中消息的衍生和目标的判定,指出公平性包含的局部目标和全局目标,利用基于适应度函数的遗传优化算法,对用二进制表示的协议空间进行优化搜索,获得满足目标的协议,并通过实例说明文中方法的可行性.     

Set partitioning for multilevel codes on a Rayleigh-fading channel

On a Rayleigh-fading channel, multilevel codes achieve larger Hamming distances than single-level codes at comparable decoder complexity and bandwidth efficiency by employing a multistage decoder. Typically, multilevel codes are designed using Ungerboeck's (1982) set partitioning. This results in a large path multiplicity that degrades the code performance significantly. In order to overcome the performance degradation, we propose a set partitioning method that greatly reduces the path multiplicity