Digital compass for multi-user beam access in mmWave cellular networks

Abstract

Beamforming in stand-alone Millimeter-Wave (mmWave) communications results in prolonged access times and latencies due to the increased number of measurements required to determine the optimal beam directions at the Mobile Station (MS) and Base Station (BS), returning the highest received signal level. Therefore, dynamic and fast access schemes that meet the Third-Generation Partnership Project (3GPP) specifications are required here. Therefore, in this paper, a novel initial access scheme is proposed for multiple MS users by leveraging for the first time a digital compass in the access procedure. Namely, when a new MS joins the footprint of a BS, it probes the channel for beacon signaling about the BS direction, i.e., broadcasted by a neighboring MS that completed beam association at previous time steps. Then, a digital compass is utilized to adjust the coordinates of the BS according to the location of the new MS. The proposed scheme is applied for a single and multi-user settings at various broadcasting approaches. This includes a single associated MS user that broadcasts information to a single incoming MS user, a single user that broadcasts signals to multiple incoming users, or all multiple associated users broadcast to multiple incoming users. Overall, the proposed schemes yield in notable efficiency in terms of the computational complexity, access times, power and energy consumption as compared to existing access schemes. Further, high success rates are achieved at the detriment of relatively higher cost.