软信息辅助硬判决译码在自由空间光通信中的应用

doi:10.12263/DZXB.20210220

电子学报 ›› 2021, Vol. 49 ›› Issue (10): 1945-1951.DOI: 10.12263/DZXB.20210220

所属专题：无线光通信及其组网技术

• 无线光通信及其组网技术 • 上一篇下一篇

软信息辅助硬判决译码在自由空间光通信中的应用

雷艺, 陈斌, 周红平, 郭凯, 郭忠义

合肥工业大学计算机与信息学院，安徽合肥 230009

收稿日期:2021-02-04 修回日期:2021-05-19 出版日期:2021-11-30
- 作者简介:
- 雷艺（通信作者）女，1990年生，重庆忠县人.合肥工业大学计算机与信息学院讲师.主要研究方向为光通信、信道编码等. E-mail:leiyi@hfut.edu.cn
  陈斌男，1989年生，安徽合肥人.合肥工业大学计算机与信息学院讲师.主要研究方向为新型编码调制技术.
- 基金资助:
- 国家自然科学基金 (62001151); 安徽省自然科学基金 (2008085QF282)

A Soft-Aided Hard-Decision Decoder for Free-Space Optical Communications

LEI Yi, CHEN Bin, ZHOU Hong-ping, GUO Kai, GUO Zhong-yi

School of Computer Science and Information Engineering, Hefei University of Technology, Hefei, Anhui 230009, China

Received:2021-02-04 Revised:2021-05-19 Online:2021-11-30 Published:2021-10-25
- Supported by:
- National Natural Science Foundation of China (62001151); Natural Science Foundation of Anhui Province (2008085QF282)

摘要/Abstract

摘要：

由于在性能和复杂度之间的良好折中，软信息辅助硬判决译码近年来受到了光通信领域的高度关注，其中包括了软信息辅助比特标记（Soft-Aided Bit-Marking, SABM）算法.为了易于硬件实现，本文基于阶梯码（Staircase Code, SCC）提出了一种改进型SABM算法（improved SABM, iSABM），称为iSABM-SCC.iSABM-SCC利用信道软信息，通过两个可信度阈值将硬判决输出比特标记为三种可信度等级，用以辅助硬判决译码识别译码错误和扩展纠错能力，达到提升阶梯码性能的目的.在受大气湍流影响的自由空间光通信中的仿真表明，iSABM-SCC性能显著优于标准SCC和RS码.以强湍流信道为例，码率为0.75的iSABM-SCC在4-PAM调制下较标准SCC产生的性能增益可达4.37 dB，在8-PAM调制下较RS码产生的性能增益可达11.06 dB.

关键词: 自由空间光通信, 前向纠错技术, 阶梯码, 硬判决译码, 软判决译码

Abstract:

Due to a good trade-off between performance and complexity, a new class of decoding schemes, called soft-aided hard-decision (SA-HD) decoders, has become particularly interesting to optical communication fields in recent years. Soft-aided bit-marking (SABM) algorithm is one of the popular ones. To be friendly for hardware implementation, this paper proposes an improved SABM (iSABM) algorithm for staircase codes (SCCs), which we call iSABM-SCC. With the help of channel soft information, iSABM-SCC marks bits into three types according to their reliabilities using two thresholds. The marked information is then used to assist the staircase decoder to prevent miscorrections and to extend the error-correcting capability, thus improving the performance of SCCs. The simulation results for free-space optical communications show that the proposed iSABM-SCC scheme achieves higher performance gains over standard SCC (S-SCC) and RS code in turbulence channels. For instance, iSABM-SCC with code rate of 0.75 has been shown to yield up to 4.37 dB performance gain when compared to S-SCC for 4-PAM and up to 11.06 dB performance gain when compared to RS code for 8-PAM in a strong turbulence channel.

Key words: free space optical communication, forward error correction, staircase code, hard-decision decoder, soft-decision decoder

中图分类号:

TN92

雷艺, 陈斌, 周红平, 郭凯, 郭忠义. 软信息辅助硬判决译码在自由空间光通信中的应用[J]. 电子学报, 2021, 49(10): 1945-1951.

LEI Yi, CHEN Bin, ZHOU Hong-ping, GUO Kai, GUO Zhong-yi. A Soft-Aided Hard-Decision Decoder for Free-Space Optical Communications[J]. Acta Electronica Sinica, 2021, 49(10): 1945-1951.

图/表 11

图1 系统模型

图2 阶梯码结构

图3 iSABM算法的译码流程

表1 S-SCC和iSABM-SCC仿真参数

R	n	v	t	w	p
0.5	88	66	3	44	22
0.75	120	105	2	60	15

图4 高斯信道下，K = 7的iSABM-SCC在不同ε1和ε2取值下的BER性能：(a) R=0.5，SNR=3.5 dB, (b) R=0.75, SNR=5.3 dB

图5 高斯信道下，码率为0.5的iSABM-SCC在不同K值下的BER性能，其中ε1=39%和ε2=15%

表2 iSABM-SCC标记的HUB和HRB占总比特数的百分比

R	$ε 1$ （HRB）	$ε 2$ （HUB）
0.5	39%	15%
0.75	82%	6%

表2 iSABM-SCC标记的HUB和HRB占总比特数的百分比

R	$ε 1$ （HRB）	$ε 2$ （HUB）
0.5	39%	15%
0.75	82%	6%

图6 弱湍流（σR=0.2）下，码率为0.5的iSABM-SCC、S-SCC、LDPC和RS码的BER性能对比：（a）2-PAM,（b）4-PAM,（c）8-PAM

图7 弱湍流（σR=0.2）下，码率为0.75的iSABM-SCC、S-SCC、LDPC和RS码的BER性能对比：（a）2-PAM,（b）4-PAM,（c）8-PAM

图8 强湍流（σR=2）下，码率为0.5的iSABM-SCC、S-SCC、LDPC和RS码的BER性能对比：（a）2-PAM,（b）4-PAM,（c）8-PAM

图9 强湍流（σR=2）下，码率为0.75的iSABM-SCC、S-SCC、LDPC和RS码的BER性能对比：（a）2-PAM,（b）4-PAM,（c）8-PAM

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软信息辅助硬判决译码在自由空间光通信中的应用

A Soft-Aided Hard-Decision Decoder for Free-Space Optical Communications

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