标题： 基于ADMM的大型MIMO码域NOMA系统检测器 显示英文标题

标题： ADMM-based Detector for Large-scale MIMO Code-domain NOMA Systems

摘要： 大规模多输入多输出（MIMO）码域非正交多址接入（CD-NOMA）技术是满足下一代无线需求的潜在候选技术，例如大规模连接和高可靠性。 本工作专注于两种主要的CD-NOMA技术：稀疏码多址接入（SCMA）和密集码多址接入（DCMA）。 在实现MIMO-CD-NOMA系统时面临的主要挑战之一是设计计算成本和复杂度可接受的最优检测器。 本文提出了一种基于交替方向乘子法（ADMM）的迭代线性检测器。 首先，将最大似然（ML）检测问题转化为共享优化问题。 将ML检测问题中的集合约束放松为框约束共享问题。 通过惩罚项引入一个替代变量，以补偿由于约束放松而造成的损失。 系统模型，即输入信号与接收信号之间的关系，被重新表述，以便所提出的共享优化问题可以被直接应用。 ADMM是一种稳健的算法，可用于分布式地解决共享问题。 所提出的检测器利用了分布式特性来降低每次迭代的成本和时间。 设计了一种基于ADMM的线性检测器，适用于三种MIMO-CD-NOMA系统：单输入多输出CD-NOMA（SIMO-CD-NOMA）、空间复用CD-NOMA（SMX-CD-NOMA）和空间调制CD-NOMA（SM-CD-NOMA）。 通过广泛的蒙特卡洛仿真，全面研究了各种系统参数和ADMM参数对计算复杂度和符号错误率（SER）的影响。 显示英文摘要

摘要： Large-scale multi-input multi-output (MIMO) code domain non-orthogonal multiple access (CD-NOMA) techniques are one of the potential candidates to address the next-generation wireless needs such as massive connectivity, and high reliability. This work focuses on two primary CD-NOMA techniques: sparse-code multiple access (SCMA) and dense-code multiple access (DCMA). One of the primary challenges in implementing MIMO-CD-NOMA systems is designing the optimal detector with affordable computation cost and complexity. This paper proposes an iterative linear detector based on the alternating direction method of multipliers (ADMM). First, the maximum likelihood (ML) detection problem is converted into a sharing optimization problem. The set constraint in the ML detection problem is relaxed into the box constraint sharing problem. An alternative variable is introduced via the penalty term, which compensates for the loss incurred by the constraint relaxation. The system models, i.e., the relation between the input signal and the received signal, are reformulated so that the proposed sharing optimization problem can be readily applied. The ADMM is a robust algorithm to solve the sharing problem in a distributed manner. The proposed detector leverages the distributive nature to reduce per-iteration cost and time. An ADMM-based linear detector is designed for three MIMO-CD-NOMA systems: single input multi output CD-NOMA (SIMO-CD-NOMA), spatial multiplexing CD-NOMA (SMX-CD-NOMA), and spatial modulated CD-NOMA (SM-CD-NOMA). The impact of various system parameters and ADMM parameters on computational complexity and symbol error rate (SER) has been thoroughly examined through extensive Monte Carlo simulations.