Hybrid Beamforming for Wideband Millimeter Wave MIMO Integrated Sensing and Communications

In this letter, we propose a true-time-delayer network assisted hybrid beamforming scheme for wideband millimeter wave multiple-input multiple-output integrated sensing and communications. By jointly optimizing the digital beamformer, the true-time-delayer network and the phase shifter network, we aim at making the sum of beam patterns across all subcarriers approach a predefined sensing beam pattern, subject to the constraints of the signal-to-interference-plus-noise ratio requirements of communication users and the maximum transmit power of the base station. To improve the design flexibility, the sensing beam pattern is distributed among different subcarriers for optimization, with phase vectors introduced to transform the modulus summation into a linear summation. Additionally, by decoupling the multi-variable constraint, we employ the alternating direction method of multipliers to decompose the original problem into manageable subproblems, which are iteratively optimized. Simulation results demonstrate that the proposed scheme outperforms existing hybrid beamforming schemes in terms of beam pattern and sensing performance.