Design and analysis of irregular sparse code multiple access

Sparse Code Multiple Access (SCMA) is an excellent approach to support massive connections and short time-delay, which are the two key requirements in the future fifth generation (5G) communication system. Due to the drawback that traditional SCMA can´t serve users with different business needs in the same scenario, we propose an irregular Sparse Code Multiple Access (SCMA) in this paper. In contrast with the traditional SCMA system based on the regular structure, the irregular SCMA can handle massive connections and short time delay in the same system simultaneously by assigning different codebooks with various dimensions for different users who demand for divers performance needs. Simulation results illustrate that irregular SCMA can achieve about 0.7 dB gain over regular SCMA in terms of the same bit error rate (BER) condition.