Target Sensing in Wideband Massive MIMO-ISAC Systems in the Presence of Beam Squint

Integrated sensing and communication (ISAC) combined with massive multiple-input multiple-output (MIMO) can simultaneously improve the spectral efficiency and the sensing capability. However, the use of wide bandwidth and a large number of antennas introduces severe beam squint effects, significantly degrading the target sensing performance. In this paper, we propose a novel approach to estimate the target parameters for wideband massive MIMO-ISAC systems in the presence of beam squint. We first investigate the echo signal model for target sensing when employing both the large signal bandwidth and the antenna array. Then, we formulate the received echo signals as a third-order tensor that admits a canonical polyadic decomposition model. Based on the model, we analyze the associated uniqueness condition and propose a tensor-based estimator to extract the target parameters including the direction of angles, ranges, and velocities. The numerical results demonstrate that the proposed estimator achieves superior target sensing performance over existing methods.