Interference-Limited Zero-Crossing Modulation MIMO System for Energy-Efficient Tbps Links

Abstract

Sub-THz wireless links targeting Tbps throughput face a fundamental tension between bandwidth and energy efficiency. Zero-Crossing Modulation (ZXM) is a promising approach to reduce receiver power consumption by combining 1-bit quantization with temporal oversampling. However, the resulting 1-bit receive chain introduces a strong nonlinearity, which limits the applicability of conventional linear multipleinput multiple-output (MIMO) spatial equalization techniques and makes the impact of coupling and crosstalk a primary system design constraint. This motivates the use of ZXM in combination with 1-bit quantization for a quasi-optical (QO) MIMO system, where the spatial inter-stream interference is very small. Hence, we present a system-level link-budget analysis for an 8×8 QO MIMO architecture at sub-THz, based on a signal-to-interference-plus-noise ratio (SINR) analysis that treats interstream interference as additional noise after 1-bit quantization. The end-to-end coupling matrix is modeled as the cascade of antenna coupling and RF front-end crosstalk contributions. Using this framework, we quantify when the link transitions from noise-limited to interference-limited operation, show SINR saturation with increasing transmit power, and derive feasible operating regimes over distance and spectral-efficiency targets for wideband 50 GHz operation. The results substantiate the feasibility of energy-efficient Tbps-class wireless connectivity.