SNR Scaling Laws for Radio Sensing with Extremely Large-Scale MIMO

Abstract

Mobile communication networks were designed to mainly support ubiquitous wireless communications, yet they are expected to also achieve radio sensing capabilities in the near future. Most prior studies on radar sensing focus on distant targets, which usually rely on far-field assumption with uniform plane wave (UPW) models. However, with ever-increasing antenna size, together with the growing need to also sense nearby targets, the far-field assumption may become invalid. This paper studies radar sensing with extremely large-scale (XL) antenna arrays, where a generic model that takes into account both spherical wavefront and amplitude variations across array elements is developed. Furthermore, new closed-form expressions of the sensing signal-to-noise ratios (SNRs) are derived for both XL-MIMO radar and XL-phased-array radar modes. Our results reveal that different from the conventional UPW model where the SNR scales linearly and unboundedly with N for MIMO radar and with M N for phased-array radar, with M and N being the transmit and receive antenna numbers, respectively, more practical SNR scaling laws are obtained. For XL-phased-array radar with optimal power allocation, the SNR increases with M and N with diminishing returns, governed by new parameters called the transmit and receive angular spans. On the other hand, for XL-MIMO radar, while the same SNR scaling as XL-phasedarray radar is obeyed for N , the SNR first increases and then decreases with M .

Waveform Design and Performance Analysis for Full-Duplex Integrated Sensing and Communication

“…Wireless communication and radar sensing, as two most successful applications of electromagnetic radiation, were mainly developed separately in the past century, with quite different performance metrics and distinct frequency bands [2], [3]. With the continuous expansion of communication spectrum and the growing interest to bridge the cyber and physical worlds by ubiquitous sensing, there have been growing research interest in integrated sensing and communication (ISAC) [4]- [12], which aims to efficiently utilize the precious radio resources and hardware for both sensing and communication purposes.…”