This letter studies the ergodic mutual information (EMI) of keyhole multiple-input multiple-output channels having finite-alphabet input signals. The EMI is first investigated for single-stream transmission considering both cases with and without the channel state information at the transmitter. Then, the derived results are extended to the case of multi-stream transmission. Asymptotic analyses are performed in the regime of high signal-to-noise ratio (SNR). The high-SNR EMI is shown to converge to a constant with its rate of convergence determined by the diversity order. On this basis, the influence of the keyhole effect on the EMI is discussed. The analytical results are validated by numerical simulations.

翻译：本信研究了带有有限阿尔法贝输入信号的关键孔多输入多输出输出信道的相互信息(EMI),首先对EMI进行单流传输调查,同时考虑发报机的频道状态信息,然后将结果扩大到多流传输,在高信号对噪音比率(SNR)制度下进行抗药性分析,高信号对噪音的ENR EMI显示与多样性命令决定的趋同率相一致,在此基础上,讨论了关键孔效应对EMI的影响,通过数字模拟验证分析结果。