In this paper, we study the secure degrees-of-freedom (SDoF) characterization for the multiple-input multiple-output (MIMO) X channel with confidential messages and delayed CSIT. In particular, we propose a transmission scheme, which can be regarded as a generalization of the state-of-the-art scheme without security and with delayed CSIT. The key of this generalization is performing the security analysis, by which we derive the optimal duration of the artificial noise transmission phase. As a result, we derive the sum-SDoF lower bound. Furthermore, we reveal that if the number of receive antennas, denoted by N, is fixed, the minimum number of transmit antennas achieving the maximum of the lower bound is $\frac{7+\sqrt{33}}{8}N$.
翻译:在本文中,我们研究了安全自由度(SDoF)对多投入多输出(MIMO)X频道的定性,该频道载有保密信息,并延迟了CSIT,我们特别提议了一个传输计划,可被视为是无安全和延迟的CSIT最先进计划的概括。这种概括的关键是进行安全分析,从而得出人工噪音传输阶段的最佳持续时间。结果,我们得出了总和-SDoF的下限。此外,我们透露,如果N表示的接收天线数量固定不变,达到下限最大天线的传输天线最低数量是$frac{7 ⁇ sqrt{338}N美元。