Efficient signal detectors are rather important yet challenging to achieve satisfactory performance for large-scale communication systems. This paper considers a non-orthogonal sparse code multiple access (SCMA) configuration for multiple-input multiple-output (MIMO) systems with recently proposed orthogonal time frequency space (OTFS) modulation. We develop a novel low-complexity yet effective customized Memory approximate message passing (AMP) algorithm for channel equalization and multi-user detection. Specifically, the proposed Memory AMP detector enjoys the sparsity of the channel matrix and only applies matrix-vector multiplications in each iteration for low-complexity. To alleviate the performance degradation caused by positive reinforcement problem in the iterative process, all the preceding messages are utilized to guarantee the orthogonality principle in Memory AMP detector. Simulation results are finally provided to illustrate the superiority of our Memory AMP detector over the existing solutions.

翻译：高效的信号检测器对于大规模通信系统实现令人满意的性能至关重要，但仍颇具挑战性。本文针对采用最新提出的正交时频空间（OTFS）调制的多输入多输出（MIMO）系统，考虑了一种非正交稀疏码多址接入（SCMA）配置。我们开发了一种新型低复杂度且有效的定制化记忆近似消息传递（AMP）算法，用于信道均衡与多用户检测。具体而言，所提出的记忆AMP检测器利用信道矩阵的稀疏性，并在每次迭代中仅执行矩阵-向量乘法以实现低复杂度。为缓解迭代过程中正反馈问题导致的性能下降，所有先前的消息均被用于保证记忆AMP检测器中的正交性原理。最后，仿真结果展示了我们的记忆AMP检测器相较于现有解决方案的优越性。