上行瑞利衰落信道下SCMA码本设计

Design of SCMA Codebook for Uplink Rayleigh Fading Channel

稀疏码多址接入(SCMA)是一种具有竞争力的码域非正交多址接入技术,通过将调制与稀疏扩频结合在一起,有效提升了通信系统的频谱效率。该文针对现有码本设计中存在的一些问题,提出了一种适用于上行瑞利衰落信道的新型码本设计优化方案。首先将母星座设计从实数域推广到复数域,提高码本设计的自由度;其次,以最大化最小乘积距离为目标,通过遗传算法对码本各参数进行优化。仿真结果表明提出的码本在上行瑞利衰落信道下误码率性能较以往码本有明显改善。

Sparse code multiple access (SCMA) is a competitive non-orthogonal code domain multiple access technology. By combining modulation with sparse spread spectrum, it can effectively improve the spectral efficiency of communication system. In this paper, a new optimization scheme of codebook design for uplink Rayleigh fading channel is proposed to solve the existing problems in codebook design. Firstly, the parent constellation design is extended from the real number domain to the complex number domain to improve the freedom of codebook design. Secondly, in order to maximize the minimum product distance, the parameters of the codebook were optimized by genetic algorithm. Simulation results show that the BER performance of the proposed codebook is better than that of previous codebooks in uplink Rayleigh fading channel.