Both multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) are key technologies for the fifth-generation mobile communication systems. However, interference is one of the critical challenges in MIMO–OFDM systems that degrades the overall performance. In this study, a novel interference alignment (IA) design-based diagonal-block channel charter to mitigate the interference for MIMO–OFDM systems is proposed. The proposed IA scheme can be used in physical layer security, e.g. anti-location. Based on the diagonal-block charter of the channel matrix, the optimal degree of freedom, i.e. the maximum number of multiple data streams concurrently transmitted interference-free can be achieved by IA. Correspondingly, the authors present the closed-form IA design scheme for some special scenarios, and two iterative IA ones for general scenarios in detail. Furthermore, the performance analysis of IA systems with diagonal-block channel error is provided, where the imperfect channel state information case is considered. The simulation results show that the IA design based on the diagonal-block channel can improve the sum-rate performance effectively, by sufficiently exploiting the spatial and frequency resources.

中文翻译：

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CSI不完善的MIMO–OFDM系统的最佳IA设计和性能分析

多输入多输出（MIMO）和正交频分复用（OFDM）都是第五代移动通信系统的关键技术。但是，干扰是MIMO–OFDM系统中会降低整体性能的关键挑战之一。在这项研究中，提出了一种新颖的基于干扰对准（IA）设计的对角块信道章程，以减轻MIMO-OFDM系统的干扰。提议的IA方案可用于物理层安全性，例如防定位。基于信道矩阵的对角块宪章，IA可以实现最佳的自由度，即同时传输的无干扰的多个数据流的最大数量。相应地，作者针对某些特殊情况提出了封闭形式的IA设计方案，以及针对一般情况的两个迭代IA。此外，提供了具有对角块信道误差的IA系统的性能分析，其中考虑了信道状态信息不完善的情况。仿真结果表明，通过充分利用空间和频率资源，基于对角块信道的IA设计可以有效地提高和速率性能。