An Energy-efficient ISAC Beam Management Scheme in UAV Communications

With the advantages of high flexibility and rapid deployment, unmanned aerial vehicles (UAVs) are considered as promising wireless access points for efficient emergency communication. However, UAV base stations (UAV-BSs) are characterized by their susceptibility to environmental interference, leading to jitter and prone to beam misalignment. Additionally, the operational time of a UAV-BS is constrained by the power source. To overcome these obstacles, this paper proposes an energy-efficient beam alignment and tracking scheme based on integrated sensing and communication (ISAC) technology. Specifically, beam alignment is performed based on the predicted angles obtained from the extended Kalman filtering (EKF) algorithm. Then, the beamwidth control is realized by changing the number of activated antennas based on the prediction error derived from EKF. To determine the optimal number of activated antennas for maximizing energy efficiency, a block coordinate descent based fractional programming algorithm is designed. Simulation results verify the superiority of the proposed scheme in terms of communication energy efficiency.