NOMA Joint Decoding based on Soft-Output Ordered-Statistics Decoder for Short Block Codes

TL;DR

This paper introduces a low-complexity joint decoding method for NOMA systems using short block codes, combining a novel soft-output decoder with interference cancellation techniques to improve error rates and reduce complexity.

Contribution

It proposes a new low-complexity soft-output ordered-statistics decoder and an efficient joint decoding receiver for NOMA systems, enhancing performance and convergence speed.

Findings

Achieves lower bit-error rate than SIC decoding

Reduces decoding complexity significantly

Maintains mutual information properties of original SOSD

Abstract

In this paper, we design the joint decoding (JD) of non-orthogonal multiple access (NOMA) systems employing short block length codes. We first proposed a low-complexity soft-output ordered-statistics decoding (LC-SOSD) based on a decoding stopping condition, derived from approximations of the a-posterior probabilities of codeword estimates. Simulation results show that LC-SOSD has the similar mutual information transform property to the original SOSD with a significantly reduced complexity. Then, based on the analysis, an efficient JD receiver which combines the parallel interference cancellation (PIC) and the proposed LC-SOSD is developed for NOMA systems. Two novel techniques, namely decoding switch (DS) and decoding combiner (DC), are introduced to accelerate the convergence speed. Simulation results show that the proposed receiver can achieve a lower bit-error rate (BER) compared to the successive interference cancellation (SIC) decoding over the additive-white-Gaussian-noise (AWGN) and fading channel, with a lower complexity in terms of the number of decoding iterations.