Beam design for beam switching based millimeter wave vehicle-to-infrastructure communications

Beam alignment is a source of overhead in mobile millimeter wave communication systems due to the need for frequent repointing. Beam switching architectures can reduce the amount of repointing required by leveraging position prediction. This paper presents an optimization of beam design in terms of rate. We consider a non-congested two-lane highway scenario where road side units are installed on lighting poles. Under this scenario, line-of-sight to the road side unit is very likely and vehicle speed does not vary much. We formulate and solve numerically using a gradient descent method for an optimal beam design to maximize the data rate for non-overlap beams. The result shows close performance to the equal coverage beam design. We study the effect of the overlap on the average rate and outage and compare the equal coverage with the equal beamwidth design. Numerical examples show that the equal coverage design can achieve up to 1.5× the rate of the equal beamwidth design confirming the importance of the choice of beam design.