论文标题
稀疏或致密：代码域NOMA系统的比较研究
Sparse or Dense: A Comparative Study of Code-Domain NOMA Systems
论文作者
论文摘要
本文的重点是代码域非正交多访问（CD-NOMA），这是一个新兴的范式，可支持未来机器型无线网络的大规模连通性。我们采用一种比较方法来研究两种类型的过载CD-NOMA，即稀疏代码多重访问（SCMA）和密集代码多访问（DCMA），它们在其代码书具有稀疏性方面彼此之间相同。通过分析瑞利褪色渠道中的个人多样性订单（DO），发现DCMA可以设计为享受全部DO，这等于系统中最大的资源节点数量。这与SCMA相反，SCMA的错误率受到有限的影响等于CodeBook的稀疏性（即，每个用户占据的有效资源节点数量）。我们针对代码书设计标准进行了理论分析，并建议将广义的球体解码器用于DCMA检测。我们在“ 4x6”下（即六个用户在四个子载波上进行通信）和“ 5x10” Noma设置下的两种类型的多个访问方案评估，并揭示DCMA在雷利淡淡的淡入淡出通道中的错误率显着提高，同时具有与SCMA相比的复杂性。
This paper is focused on code-domain non-orthogonal multiple access (CD-NOMA), which is an emerging paradigm to support massive connectivity for future machine-type wireless networks. We take a comparative approach to study two types of overloaded CD-NOMA, i.e., sparse code multiple access (SCMA) and dense code multiple access (DCMA), which are distinctive from each other in terms of their codebooks having sparsity or not. By analysing their individual diversity orders (DO) in Rayleigh fading channels, it is found that DCMA can be designed to enjoy full DO which is equal to the maximum number of resource nodes in the system. This is in contrast to SCMA whose error rate suffers from limited DO equal to the codebook sparsity (i.e., the effective number of resource nodes occupied by each user). We conduct theoretical analysis for the codebook design criteria and propose to use generalized sphere decoder for DCMA detection. We numerically evaluate two types of multiple access schemes under "4x6" (i.e., six users communicate over four subcarriers) and "5x10" NOMA settings and reveal that DCMA gives rise to significantly improved error rate performance in Rayleigh fading channels, whilst having decoding complexity comparable to that of SCMA.
