检索结果-南通市图书馆

A novel construction method of QC-LDPC codes based on the subgroup of the finite field multiplicative group for optical transmission systems

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2016年第1期12卷 61-64页

作者：袁建国周光香高文春王永林金朝庞宇 Key Laboratory of Optical communication and Networks Chongqing University of Posts and Telecommunications

According to the requirements of the increasing development for optical transmission systems,a novel construction method of quasi-cyclic low-density parity-check(QC-LDPC) codes based on the subgroup of the finite field multiplicative group is ***,this construction method can effectively avoid the girth-4 phenomena and has the advantages such as simpler construction,easier implementation,lower encoding/decoding complexity,better girth properties and more flexible adjustment for the code length and code *** simulation results show that the error correction performance of the QC-LDPC(3 780,3 540) code with the code rate of 93.7% constructed by this proposed method is excellent,its net coding gain is respectively 0.3dB,0.55dB,1.4dB and 1.98dB higher than those of the QC-LDPC(5 334,4 962) code constructed by the method based on the inverse element characteristics in the finite field multiplicative group,the SCG-LDPC(3 969,3 720) code constructed by the systematically constructed Gallager(SCG) random construction method,the LDPC(32 640,30 592) code in ITU-T G.975.1 and the classic RS(255,239) code which is widely used in optical transmission systems in ITU-T G.975 at the bit error rate(BER) of ***,the constructed QC-LDPC(3 780,3 540) code is more suitable for optical transmission systems.

关键词： Bit error rate Convolutional codes Error correction Inverse problems Light transmission Optical communication satellite communication systems Transmissions

Construction of type-Ⅱ QC-LDPC codes with fast encoding based on perfect cyclic difference sets

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2017年第5期13卷 358-362页

作者：李玲香李海兵李季碧江华 School of Electronics and Information Engineering Hunan University of Science and Engineering BNP Paribas College of communication and Information Engineering Chongqing University of Posts and Telecommunications Key Laboratory of Granular Computing Minnan Normal University

In view of the problems that the encoding complexity of quasi-cyclic low-density parity-check(QC-LDPC) codes is high and the minimum distance is not large enough which leads to the degradation of the error-correction performance, the new irregular type-Ⅱ QC-LDPC codes based on perfect cyclic difference sets(CDSs) are constructed. The parity check matrices of these type-Ⅱ QC-LDPC codes consist of the zero matrices with weight of 0, the circulant permutation matrices(CPMs) with weight of 1 and the circulant matrices with weight of 2(W2CMs). The introduction of W2CMs in parity check matrices makes it possible to achieve the larger minimum distance which can improve the error-correction performance of the codes. The Tanner graphs of these codes have no girth-4, thus they have the excellent decoding convergence characteristics. In addition, because the parity check matrices have the quasi-dual diagonal structure, the fast encoding algorithm can reduce the encoding complexity effectively. Simulation results show that the new type-Ⅱ QC-LDPC codes can achieve a more excellent error-correction performance and have no error floor phenomenon over the additive white Gaussian noise(AWGN) channel with sum-product algorithm(SPA) iterative decoding.

关键词： Convolutional codes Encoding (symbols) Error correction Errors Gaussian noise (electronic) Iterative decoding Iterative methods Matrix algebra satellite communication systems Set theory Signal encoding Turbo codes White noise

Resource Allocation in Variable Bandwidth MF-TDMA satellite communications

在线全文

学校读者我要写书评

暂无评论

Resource Allocation in Variable Bandwidth MF-TDMA Satellite ...

A Practical Method for Improving Delay Performance of Time Slot Allocation in DVB-RCS

2006 8th International Conference on Signal Processing

作者： PAN Xiaofei WEI Li Institute of communications Engineering PLA Univ.of Sci.＆ Tech

ISBN: (纸本)0780397371

＜正＞In modern satellite communication systems,because of the high efficiency and flexibility,multi-frequency time-division multiple access（MF-TDMA） becomes one of hot *** this paper we present a resource allocation algorithm for the variable bandwidth MF-TDMA *** proposed algorithm uses new concept - Unit Block,as the basic unit of resource allocation,and gives an outstanding assignment plan within a comparatively short period of time.

关键词： satellite communication systems

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2009年第2期22卷 174-183页

作者：秦勇张军张涛董启甲北京航空航天大学电子信息工程学院

In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...

关键词： satellite communication systems time division multiple access DVB-RCS time slot allocation models delay