YOLO: An Efficient Terahertz Band Integrated Sensing and Communications Scheme With Beam Squint

Using communications signals for dynamic target sensing is an important component of integrated sensing and communications (ISAC). In this paper, we propose to utilize the beam squint effect to realize fast non-cooperative dynamic target sensing in massive multiple input and multiple output (MIMO) Terahertz band communications systems. Specifically, we construct a wideband channel model of the echo signals, and design a beamforming strategy that controls the range of beam squint by adjusting the values of phase shifters and true time delay lines. With this design, beams at different subcarriers can be aligned along different directions in a planned way. Then the received echo signals at different subcarriers will carry target information in different directions, based on which the targets’ angles can be estimated through sophisticatedly designed algorithm. Moreover, we propose a supporting method based on extended array signal estimation, which utilizes the phase changes of different frequency subcarriers within different orthogonal frequency division multiplexing (OFDM) symbols to estimate the distances and velocities of dynamic targets. Interestingly, the proposed sensing scheme only needs to transmit and receive the signals once, which can be termed as You Only Listen Once (YOLO). Compared with the traditional ISAC methods that require time consuming beam sweeping, the proposed one greatly reduces the sensing overhead. Simulation results are provided to demonstrate the effectiveness of the proposed schemes.

I. Introduction

Integrated sensing and communications (ISAC) is anticipated to be a key technology of sixth generation (6G) mobile communications [1], [2], [3]. Its basic idea is to use communication signals to sense various aspects of the real physical world, such as target’s position, architectural composition, human activity, etc. Once the ISAC system obtains such information, it can not only enhance the data transmission performance [4], but also support a variety of intelligent applications, such as connected vehicles and smart factory [5], [6].