Geometry-Assisted Initial Access and Link Maintenance in mmWave 5G Communication Networks

Beamforming using highly directional antennas is inevitable to compensate the propagation losses and enable communication in the millimeter wave (mmWave) band. However, this directivity makes mmWave links fragile and sensitive to environment dynamics and blockage. Consequently, initial access and management of the mmWave links in dynamic environments turns to be a big challenging issue, especially in dense network scenarios. In particular, a massive amount of beamforming training (BT) overhead with high delay is needed to establish the mmWave link between a user device (UD) and the deployed small cells (SCs). The consequences are become more severe in case of mobility, since frequent handovers (HOs) between different beams/SCs is needed to preserve the connection with moving UDs. Inspired by the fact that directionality makes the mmWave communications to be geometry and location driven, this paper proposes a geometry-based schemes for the initial access and management of mmWave links. In the proposed schemes, geometric information of the target area including the UDs locations, SCs coordinates and the target area maps are exploited to alleviate the complexity of the exhaustive-based BT. The high impact of the proposed mmWave link initial access and management schemes over the conventional ones in different terms such as BT complexity and total energy consumption rates is proved via simulation analysis.