Localization bound based beamforming optimization for multicarrier mmWave MIMO

In this paper we study optimal beamforming policy to minimize the Cramer Rao Lower Bound (CRLB) of joint angle of arrival (AoA) and time delay estimation for a multicarrier millimeter wave (mmWave) system. Considering one single base station (BS) with rough a priori knowledge of channel coefficients and location information of the mobile station (MS), we show that it is possible to improve the accuracy of AoA and time delay estimation, and hence of mobile station (MS) positioning, by means of optimized beamforming. Mathematical formulation of the CRLB is first introduced and the related optimization problem is solved for a each single subcarrier independently. Then we propose a solution optimizing the beamformer jointly for the multicarrier system. A few examples are provided to illustrate the benefits from bound-based beamforming optimization.