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1.
针对服从对数正态分布的大气弱湍流信道模型,选用极化码来改善FSO系统传输性能。引入一种基于3×3核心矩阵的置信传播(BP)译码方法,对核心矩阵、码字长度、以及基本单元计算式进行了改进。对比采用新型BP译码方法与传统BP译码方法的FSO系统误码率性能。仿真实验结果表明,改进型BP译码方法与传统BP译码方法相比有着更低的误码率。由于系统构造的原因,改进型BP译码占用的存储空间较少、译码延迟时间短,在码长较长的情况下,对FSO系统传输性能有较大的提升。 相似文献
2.
极化码作为一种纠错码,具有较好的编译码性能,已成为5G短码控制信道的标准编码方案。但在码长较短时,其性能不够优异。提出一种基于增强奇偶校验码级联极化码的新型编译码方法,在原有的奇偶校验位后设立增强校验位,对校验方程中信道可靠度较低的信息位进行双重校验,辅助奇偶校验码在译码过程中对路径进行修剪,以此提高路径选择的可靠性。仿真结果表明,在相同信道、相同码率码长下,本文提出的新型编译码方法比循环冗余校验(cyclic redundancy check,CRC)码级联极化码、奇偶校验(parity check,PC)码级联极化码误码性能更优异。在高斯信道下,当码长为128、码率为1/2、误码率为10-3时,本文提出的基于增强PC码级联的极化码比PC码级联的极化码获得了约0.3dB增益,与CRC辅助的极化码相比获得了约0.4 dB增益。 相似文献
3.
The ’polar coding’ proposed by Dr. Ar kan can achieve the symmetric capacity of binary-input discrete memoryless channels (B-DMC). The generator matrix of polar codes is GN=BNFn for N=2n , BN was a permutation matrix. In the article it was realized with an interleaver, so the matrix production of GN was avoided; then the generator matrix was just determined by the matrix Fn which was constructed with three sub-matrixes of Fn-1 and one 2N-1 order zero matrix, it was deal with fast Hadamard transform (FHT) algorithm. The complexity of the new scheme was reduced sharply, and an iterative algorithm also can be used. The example showed that when N=8, complexity of the encoding scheme was just 16 which is obviously less than that of original encoding scheme 36. 相似文献
4.
针对极化码的连续消除列表(successive cancellation list,SCL)译码算法的高时延问题,提出了基于对数似然比的多比特SCL(multi-bit SCL,MSCL)译码算法,可以在一个判决时刻同时译出多个码字比特,在不损失译码性能的前提下,将译码时延由3N-2个时钟降为4N/M-2个时钟,相比于现有的多比特SCL译码算法,MSCL译码算法具有更低的路径度量值计算复杂度。为了降低循环冗余校验(cyclical redundancy check, CRC)辅助的SCL(CRC aided SCL,CA-SCL)译码算法的译码时延以及存储空间,提出了分段CRC辅助的MSCL(segmented CRC-aided MSCL,SCA-MSCL)译码算法,并提出了分段信息码字长度修正算法,来保证在信息位索引集A不变的前提下,实现每一分段结尾处对应的信息位索引能够被M整除。SCA-MSCL算法可以借助多个CRC判决来尽可能早地输出译码码字,从而减少译码器的存储空间以及译码时延。 相似文献
5.
A simple decoding method for even minimum-distance Bose-Chaudhuri-Hochquenghem (BCH) codes is proposed. In the method the coefficients of an error locator polynomial are given as simple determinants (named Q determinants) composed of syndromes. The error evaluator is realized as a Q determinant divided by an error locator polynomial. The Q determinants can be efficiently obtained with very simple calculations on syndromes enabling the realization of a high-speed decoder of simple configuration. The number of calculations in obtaining the error locator and the error evaluator with the proposed method is smaller than that with the widely used Berlekamp-Massey algorithm when the number of correctable errors of the code is five or less. The proposed method can also be applied to the binary narrow-sense BCH codes of odd minimum distance 相似文献
6.
Ren Jian 《电子科学学刊(英文版)》1996,13(1):23-30
Suppose C is an irreducible algebraic curve of genus g, C*(D,G) is an algebraic geometric code with designed minimum distance d* = deg(G)-2g 2. In this paper, a decoding algorithm based on Fundamental Iterative Algorithm(FIA) is presented, also its reasonableness is proved. In fact, our decoding algorithm is a modification of the algorithm proposed by G. L. Fend and T. R. N. Rao(1993) and can correct any received words with errors not more than (d*-1)/2, whereas the complexity is only about one half as much as Feng and Rao's. The procedure can be implemented easily by hardware or software. 相似文献
7.
The typeⅡ codes have been studied widely in applications since their appearance. With analysis of the algebraic structure of finite field of order 4 (i.e., GF(4)), some necessary and sufficient conditions that a generalized H-code (i.e., GH-code) is a type Ⅱ code over GF(4) are given in this article, and an efficient and simple method to generate type Ⅱ codes from GH-codes over GF(4) is shown. The conclusions further extend the coding theory of type Ⅱ. 相似文献
8.
Ibrahim Beram Jasim Oguz Bayat Osman N. Ucan 《International Journal of Communication Systems》2019,32(11)
In this paper, we concatenated of three‐dimensional parity check (3D‐PC) block and polar codes for improving error correction performance and bit error rate (BER). Three different sizes of 3D parity check blocks (4 × 4 × 4, 8 × 8 × 8, and 16 × 16 × 16) are used for polar code concatenation. The 4 × 4 × 4 block returns the best performance, but higher complexity of decoder is needed unlikely. The 8 × 8 × 8 has returned acceptable complexity and good performacne. The complexity of decoder is less in the case of 16 × 16 × 16 with slight performance. The performance of the 3D‐PC is reduced when the codewords length is increased. The experiment considered the presence of additive white Gaussian noise (AWGN) with Rayleigh and Rician fading environments. 3D‐PC and polar code concatenation is more precise with codewords of short length, whereas there is insufficient concatenation accuracy with longer codewords. The outcomes of this study contain comparison between AWGN, Rayleigh, and Rician environments. The AWGN is noticed to have a lesser negative impact on the performance of code. Furthermore, increasing the code length may slightly fill the gap of performance between the concatenated and none concatenated polar codes due to the impact of code length on parity check code performance. Simulation results showed the coding performance in case of the polar code with concatenation and without concatenation for different code lengths. Generally, the 3D‐PC polar code concatenation is drawn the optimal result in AWGN environments. 相似文献
9.
In this paper, only narrow-sense primitive BCH codes over GF(q) are considered. A formula, that can be used in many cases, is first presented for computing the dimension of BCH codes.
It improves the result given by MacWilliams and Sloane in 1977. A new method for finding the dimension of all types of BCH
codes is proposed. In second part, it is proved that the BCH bound is the leader of some cyclotomic coset, and we guess that
the minimum distance for any BCH code is also the leader of some cyclotomic coset.
Supported by the National Natural Science Foundation of China 相似文献
10.
This article proposes a novel nonlinear network code in the GF(2m) finite field. Different from previous linear network codes that linearly mix multiple input flows, the proposed nonlinear network code mixes input flows through both multiplication and exponentiation in the GF(2m). Three relevant rules for selecting proper parameters for the proposed nonlinear network code are discussed, and the relationship between the power parameter and the coding coefficient K is explored. Further analysis shows that the proposed nonlinear network code is equivalent to a linear network code with deterministic coefficients. 相似文献
11.
基于GF(q)上纠错码的生成矩阵提出了一身份验证方案,证明了在随机预言模型中给出的协议是一零知识交互证明,并显示出通过参数的适当选取,此方案是安全的。 相似文献
12.
13.
针对多元空间耦合低密度奇偶校验(Spatially-Coupled Low-Density Parity-Check,SC-LDPC)码在二进制擦除信道(Binary Erasure Channel,BEC)上置信传播(Belief Propagation,BP)译码的译码波速度分析复杂度较高的问题,提出了内插密度演进(Density Evolution,DE)算法。内插DE算法利用一维函数在非耦合DE递归式的不动点间插值密度来近似表示轮廓译码(Decoding Profile,DP),避免了高维耦合DE递归式的迭代,从而降低了计算复杂度。仿真和分析结果表明,在相同的度分布和信道条件下,内插DE算法计算的译码波速度与传统的耦合DE算法计算的译码波速度误差在\[0,0.05\],特别在信道删除概率为耦合DE算法的BP阈值时,两者测得速度相等;由内插DE算法计算所得的BP阈值与耦合DE算法的BP阈值相等。 相似文献
14.
刘冬旭 《信息安全与通信保密》1999,(4)
给出了有限域上周期序列在改变几个比特的情况下,其极小多项式及线性复杂度的计算公式,并对其中只改变了一个比特的序列进行了深入的分析,最后得出m序列及周期为2~n序列在改变任意一个比特后的线性复杂度。 相似文献
15.
本文给出了q元Alternant码的最小距离一个新的下界,改进了以往有关结果。此外,本文将指出,文献[1]关于Alternant码的最小距离的结果,一般是不成立的。 相似文献
16.
17.
In this letter, it is shown that a fast, prime-factor discrete Fourier transform (DFT) algorithm can be modified to compute Fourier-like transforms of long sequences of 2/sup m/-1 points over GF(2/sup m/), where 8/spl les/m/spl les/10. Using these transforms, together with the Berlekamp-Massey algorithm, the complexity of the transform-domain decoder for correcting both errors and erasures of the Reed-Solomon codes of block length 2/sup m/-1 over GF(2/sup m/) for 8/spl les/m/spl les/10 is reduced substantially from the previous time-domain decoder. A computer simulation verifies these new results. 相似文献
18.
Bhandari M.C. Garg M.S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1992,38(5):1564-1567
19.
In this paper, we investigate and compare the asymptotic performance of concatenated convolutional coding schemes over GF(4) over additive white Gaussian noise (AWGN) channels. Both parallel concatenated codes (PCC) and serial concatenated codes (SCC) are considered. We construct such codes using optimal non‐binary convolutional codes where optimality is in the sense of achieving the largest minimum distance for a fixed number of encoder states. Code rates of the form k0/(k0 + 1) for k0=1, 8, and 64 are considered, which suite a wide spectrum of communications applications. For all of these code rates, we find the minimum distance and the corresponding multiplicity for both concatenated code systems. This is accomplished by feeding the encoder with all possible weight‐two and weight‐three input information patterns and monitoring, at the output of the encoder, the weight of the corresponding codewords and their multiplicity. Our analytical results indicate that the SCC codes considerably outperform their counterpart PCC codes at a much lower complexity. Inspired by the superiority of SCC codes, we also discuss a mathematical approach for analysing such codes, leading to a more comprehensive analysis and allowing for further improvement in performance by giving insights on designing a proper interleaver that is capable of eliminating the dominant error patterns. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献