Fundamental Limits for Jammer-Resilient Communication in Finite-Resolution MIMO

TL;DR

This paper establishes fundamental limits on the effectiveness of MIMO systems with finite-resolution ADCs in resisting jamming, showing that high jammer power inevitably degrades mutual information regardless of ADC strategy.

Contribution

It provides a fundamental bound on mutual information for finite-resolution MIMO systems under jamming, revealing the limitations imposed by ADC quantization.

Findings

Mutual information tends to zero as jammer power increases, regardless of ADC quantization.

Increasing ADC resolution by 1 bit can counteract a 6.02 dB increase in jamming power.

Finite-resolution ADCs fundamentally limit jammer mitigation in MIMO systems.

Abstract

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, regardless of the quantization strategy. 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.