Statistical CSI Assisted Beamforming for Co-Existence of MIMO Radar and MIMO Communication System

When the radar system and communication system share the same frequency band, it will inevitably cause relatively serious interference. In this paper, a multiple-input multiple-output (MIMO) radar and MIMO communication co-existence system is considered, which comprises a communication base station (BS), a user, a radar BS, and a radar target. The objective is to improve the communication performance with statistical channel state information by jointly designing the communication beamforming matrix and radar beampattern matrix, where the waveform similarity constraint is considered to ensure the detection performance of radar beampattern. We first derive the asymptotic approximation of the achievable ergodic rate by utilizing large random matrix theory. Based on this result, we obtain the closed-form expressions for the communication beamforming matrix and radar beampattern matrix by employing the water-filling algorithm and removing the rank-one constraint, respectively. Then, the solution for optimizing radar beampattern matrix that satisfies rank-one constraint can be recovered through the Gaussian randomization algorithm. Finally, the simulation results verify the accuracy of the asymptotic approximation and demonstrate the existence of trade-off between communication quality and radar performance.