This paper investigates the performance of iterative interference alignment (IA) with spatial hole sensing in K-user multi-input multi-output (MIMO) cognitive radio (CR) networks. In the considered network, there are some unused degrees of freedom (DoF) or equivalently spatial holes in the primary network (PN) where the secondary network (SN) users communicate without causing harmful interference to the PN receivers. First, the generalized likelihood ratio test method is utilized to determine the availability of the unused DoFs; then, it is decided whether individual primary streams are present in the PN. With the aid of precoding and suppression matrices generated by an iterative IA approach, the interferences in the PN that are caused by the SN are aligned, and due to the secondary transmission, interference leakage on the k^th primary receiver decreases below 10^− 6. The effects of the detection threshold values and the number of transmitter and receiver antennas are investigated in terms of detection and false alarm probability. Finally, the amplify-and-forward (AF) relaying scheme in the SN is evaluated and the impact of the relaying architecture on the system performance is analyzed.

本文研究了迭代干涉对齐 (IA) 与K 中空间空洞感测的性能- 用户多输入多输出 (MIMO) 认知无线电 (CR) 网络。在所考虑的网络中，在主网络 (PN) 中存在一些未使用的自由度 (DoF) 或等效的空间空洞，其中次级网络 (SN) 用户在不会对 PN 接收器造成有害干扰的情况下进行通信。首先，利用广义似然比测试方法来确定未使用的自由度的可用性；然后，决定单个主流是否存在于 PN 中。借助迭代 IA 方法生成的预编码和抑制矩阵，SN 引起的 PN 中的干扰对齐，并且由于二次传输，第k^个主接收机上的干扰泄漏降低到 10 ^{− 6 以下}. 在检测和虚警概率方面研究了检测阈值和发射机和接收机天线数量的影响。最后，对SN中的放大转发（AF）中继方案进行了评估，并分析了中继架构对系统性能的影响。