Spatial filtering based on multiple-input multiple-output (MIMO) processing is a powerful method for jammer mitigation. In principle, a MIMO receiver can null the interference of a single-antenna jammer at the cost of only one degree of freedom - if the number of receive antennas is large, communication performance is barely affected. In this paper, we show that the potential for MIMO jammer mitigation based on the digital outputs of finite-resolution analog-to-digital converters (ADCs) is fundamentally worse: Strong jammers will either cause the ADCs to saturate (when the ADCs' quantization range is small) or drown legitimate communication signals in quantization noise (when the ADCs' quantization range is large). We provide a fundamental bound on the mutual information between the quantized receive signal and the legitimate transmit signal. Our bound shows that, for any fixed ADC resolution, the mutual information tends to zero as the jammer power tends to infinity. Our bound also confirms the intuition that for every 6.02 dB increase in jamming power, the ADC resolution must be increased by 1 bit in order to prevent the mutual information from vanishing.

翻译：基于多输入多输出（MIMO）处理的空间滤波是抑制干扰的一种有力方法。原则上，MIMO接收机可以仅以牺牲一个自由度为代价来抵消单天线干扰机的干扰——如果接收天线数量足够大，通信性能几乎不受影响。本文表明，基于有限分辨率模数转换器（ADC）数字输出的MIMO干扰抑制潜力从根本上来说更差：强干扰要么会导致ADC饱和（当ADC量化范围较小时），要么会使合法通信信号淹没在量化噪声中（当ADC量化范围较大时）。我们给出了量化接收信号与合法发射信号之间互信息的基本界限。该界限表明，对于任何固定ADC分辨率，当干扰功率趋于无穷大时，互信息趋于零。我们的界限还证实了直觉：每增加6.02 dB的干扰功率，ADC分辨率必须提高1比特，以防止互信息消失。