Fast Beam Tracking Discontinuous Reception for D2D-Based UAV MmWave Communication

The device-to-device (D2D) communication integrated with the millimeter-wave (mmWave) air interface will play a significant role in the future mobile communication in terms of high transmission rate and deployment flexibility. Meanwhile, unmanned aerial vehicles (UAVs) are promoted as D2D nodes to support D2D-enabled networks for broad coverage. In this paper, we provide a new D2D-based UAV mmWave communication framework, in which the UAVs are mobile nodes and have stringent energy constraints. Therefore, the energy-efficient technology which can turn on the UAVs' radio only when necessary and overcome the resulting easily-occurred beam misalignments due to the radio OFF periods and the aircrafts' agile mobility is required urgently. To tackle this issue, we propose a novel fast beam tracking discontinuous reception (FBT-DRX) mechanism. A new Semi-Markov model is designed to analytically investigate the statistical property of the proposed scheme. Different from many published works on DRX with beamforming, we take the impact of UAV movements into account when deriving the exact closed-form expressions of sleep ratio and average packet delay. Finally, the numerical results are supplied to evaluate the effects of different key parameters on the system performance, and demonstrate that the FBT-DRX mechanism can perform well both in power saving and packet delay in the considered framework.