Continuous Beam Alignment for Mobile MIMO

TL;DR

This paper introduces a continuous beam alignment method for mobile MIMO systems that predicts and adjusts beam directions in real-time, significantly reducing pilot overhead and improving signal quality without extra pilot signals.

Contribution

It proposes a novel continuous beam tracking model that updates beam directions in real-time using rate variation prediction, reducing overhead and enhancing performance.

Findings

Reduces pilot overhead by up to 87%.

Improves SNR and reduces MSE of beam directions.

Achieves similar tracking duration as existing methods.

Abstract

Millimeter-wave transceivers use large antenna arrays to form narrow high-directional beams and overcome severe attenuation. Narrow beams require large signaling overhead to be aligned if no prior information about beam directions is available. Moreover, beams drift with time due to user mobility and may need to be realigned. Beam tracking is commonly used to keep the beams tightly coupled and eliminate the overhead associated with realignment. Hence, with periodic measurements, beams are adjusted before they lose alignment. We propose a model where the receiver adjusts beam direction "continuously" over each physical-layer sample according to a carefully calculated estimate of the continuous variation of the beams. In our approach, the change of direction is updated using the rate variation prediction of beam angles via three different solutions. Our approach incurs no additional overhead in pilots, yet, the performance of beam tracking is improved significantly. Numerical results reveal an SNR enhancement associated with reducing the MSE of the beam directions. In addition, our approach reduces the pilot overhead by 60% and up to 87% while achieving a similar total tracking duration as the state-of-the-art.