Generalized Block Markov Superposition Transmission over Free-Space Optical Links  

作　　者：Jinshun Zhu Shancheng Zhao Xiao Ma 

机构地区：[1]School of Electronics and Information Technology,Sun Yat-sen University [2]College of Information Science and Technology,Jinan University [3]School of Data and Computer Science,Sun Yat-sen University [4]Guangdong Key Laboratory of Information Security Technology,Sun Yat-sen University

出　　处：《China Communications》2017年第9期80-93,共14页中国通信（英文版）

基　　金：partially supported by the Basic Research Project of Guangdong Provincial Natural Science Foundation (No.2016A030308008);the National Natural Science Foundation of China (No.91438101 and No.61501206);the National Basic Research Program of China (973 Program) (No.2012CB316100)

摘　　要：In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.

关 键 词：atmospheric turbulence channel block Markov superposition transmission(BMST) free-space optical communications gamma-gamma channel model sliding-window decoding algorithm time diversity 

分 类 号：TN929.1[电子电信—通信与信息系统]