Design of Power-Imbalanced SCMA Codebook

TL;DR

This paper introduces a novel class of SCMA codebooks with power imbalance, optimized using genetic algorithms, resulting in improved error performance for downlink multiuser communication.

Contribution

It proposes a new power-imbalanced SCMA codebook design based on Star-QAM and genetic algorithms, differing from traditional uniform power schemes.

Findings

Enhanced error rate performance over Gaussian channels

Improved performance under Rayleigh fading channels

Effective optimization of Euclidean and product distances

Abstract

Sparse code multiple access (SCMA) is a promising multiuser communication technique for the enabling of future massive machine-type networks. Unlike existing codebook design schemes assuming uniform power allocation, we present a novel class of SCMA codebooks which display power imbalance among different users for downlink transmission. Based on the Star-QAM mother constellation structure and with the aid of genetic algorithm, we optimize the minimum Euclidean distance (MED) and the minimum product distance (MPD) of the proposed codebooks. Numerical simulation results show that our proposed codebooks lead to significantly improved error rate performances over Gaussian channels and Rayleigh fading channels.