Location-based Initial Access and Beam Adaptation for Millimeter Wave Systems

This paper proposes optimal beam adaptation (BA) and initial access (IA) algorithms for millimeter wave (mmWave) uplink systems, which make use of the estimated location of user equipment (UE) by access points (APs) rather than using exhausting full beam sweep for the beam direction toward UEs. Based on the location estimation, the optimal beamwidth guaranteeing the highest connection probability is derived for the optimal BA method. The proposed IA procedure selects the best AP not only based on the channel gain but also based on the location estimation, which leads to reduce the outage probability of cell-edge users. Numerical evaluation shows that both BA and IA outperform the conventional procedure in terms of of average achievable rate for the cell edge users, when separately applied. Numerical results are also provided with better performance than conventional systems without BA and IA suggested, for the case when both BA and IA are applied.