Fast Angle Estimation in MIMO System With Direction-Dependent Mutual Coupling

Ideal sensor response is always desirable in multiple-input multiple-output (MIMO) system. In practical application, however, sensors may be susceptible to unknown mutual coupling (MC), which seriously decreases the angle estimation accuracy. This letter addresses the scenario where MIMO sensors are corrupted by the direction-dependent MC effect. Taking the banded symmetric and Toeplitz characteristics of the MC matrices into consideration, a closed-form algorithm is introduced for angle estimation. The core of the proposed algorithm is to release the MC effect via selection matrices, and then obtain the angle by exploiting rotational invariance techniques. The proposed algorithm is capable of automatically paired angle estimation in MIMO system with direction-dependent MC, and it is much more efficient than current spectrum search approach. The numerical results show the validity and superiority of the proposed method.