Joint DOA and TOA Estimation for Moving MIMO Radar Based on OFDM-ISAC Signals

Integrated sensing and communication (ISAC) has emerged as a critical enabling technology for future communication networks because of its higher spectrum efficiency and lower hardware cost. Considering arrays will possibly be mounted on moving platforms in mobile ISAC scenarios, in this paper, array motion is introduced into monostatic multiple input multiple output (MIMO) radar based on orthogonal frequency division multiplexing ISAC (OFDM-ISAC) waveforms to improve the array aperture. Specifically, a time-frequency dual expansion (TFDE) framework, which exploits the channel state information (CSI) containing the entirety of the motion samplings and subcarrier information, is designed to construct a synthetic virtual array with an expanded aperture. With this TFDE framework, two array configurations are proposed and then analyzed, which can generate more virtual elements than the stationary MlMO array. Subsequently, taking into account the issues of parameter coupling, a reduced-complexity multiple signal classification with two-step decoupling (TSD-RC MUSIC) algorithm is pertinently designed to estimate the direction of arrival (DOA) and time of arrival (TOA) of targets while ensuring high estimation accuracy and low complexity. Numerical simulation verifies the effectiveness and superiority of the proposed TFDE framework and TSD-RC MUSIC algorithm under the proposed array configurations.