Line-of-Sight Communications with Antenna Misalignments

Line-of-sight (LOS) communications are becoming one of the promising use cases in the near future's wireless communications thanks to the potential use of very high carrier frequency, for example tera-hertz band. However, most traditional communication techniques have been developed assuming abundant reflected multipaths, and there is relatively not enough in-depth study regarding LOS communications. Therefore, this paper considers LOS communications from the aspect of antenna misalignments assuming multiple-in multiple-out (MIMO) is available. We propose a communication system that utilizes antenna subarrays for estimating the antenna misalignments and other necessary parameters to achieve the best performance in LOS channels. This information is fed back to the transmitter for deriving the optimal precoder. We exploit multiple techniques for enhancing the estimation performance for stable system performance. The results indicate that the performance with ideal information can be closely achieved with the proposed techniques. The proposed techniques are also shown to be flexibly applicable to any shape of Tx antenna arrays.