Construction and Decoding of Rate-Compatible Globally Coupled LDPC Codes

Ji Zhang,Huaan Li,Xijin Mu,Baoming Bai,Hengzhou Xu,Zhen Liu

doi:10.1155/2018/4397671

Abstract

This paper presents a family of rate-compatible (RC) globally coupled low-density parity-check (GC-LDPC) codes, which is constructed by combining algebraic construction method and graph extension. Specifically, the highest rate code is constructed using the algebraic method and the codes of lower rates are formed by successively extending the graph of the higher rate codes. The proposed rate-compatible codes provide more flexibility in code rate and guarantee the structural property of algebraic construction. It is confirmed, by numerical simulations over the AWGN channel, that the proposed codes have better performances than their counterpart GC-LDPC codes formed by the classical method and exhibit an approximately uniform gap to the capacity over a wide range of rates. Furthermore, a modified two-phase local/global iterative decoding scheme for GC-LDPC codes is proposed. Numerical results show that the proposed decoding scheme can reduce the unnecessary cost of local decoder at low and moderate SNRs, without any increase in the number of decoding iterations in the global decoder at high SNRs.

Highlights

Coupled low-density parity-check (GC-LDPC) codes, which were proposed by Li et al in [1,2,3,4], are a special type of LDPC codes designed for correcting random symbol errors and bursts of errors or erasures
We present a family of RC check nodes (CNs)-Globally coupled low-density parity-check (GC-LDPC) codes
We provide the simulated BER and BLER performances for RC GC-LDPC codes over the additive white Gaussian noise (AWGN) channel with QPSK signaling

Summary

Introduction

Coupled low-density parity-check (GC-LDPC) codes, which were proposed by Li et al in [1,2,3,4], are a special type of LDPC codes designed for correcting random symbol errors and bursts of errors or erasures. RC-LDPC codes have been adopted by the 3rd Generation Partnership Project (3GPP) as the channel coding scheme for 5G enhanced mobile broadband (eMBB) data channel [21] Such codes with a wide range of rates and block lengths are a family of nested codes which can be interpreted as a graph extension of high-rate codes [17, 22, 23].

Background

Rate-Compatible GC-LDPC Codes

Numerical Results

Conclusion