Design of Power-Imbalanced SCMA Codebook

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 novel class SCMA codebooks which display imbalance among different users downlink transmission. Based on Star-QAM mother constellation structure and with aid genetic algorithm, optimize minimum Euclidean distance (MED) product (MPD) proposed codebooks. Numerical simulation results show that our lead to significantly improved error rate performances over Gaussian channels Rayleigh fading channels.