ULA-Based Analog Beamforming and Mode Design for LAP-Assisted Multicasting Communication

Focusing on low-altitude platform (LAP)-assisted Internet of Things (IoT) networks, in this work, we study an analog beamforming design for promoting the multicasting communication performance from LAP to massive ground users. In particular, we adopt a uniform linear array (ULA) based antenna structure for realizing analog beamforming at LAP and investigate the beamforming scheme with multiple modes. Each beamforming mode contains a designed elevation angle for the power concentration in analog beamforming and a designated transmit power level. Accordingly, we formulate a problem maximizing LAP-assisted multicasting throughput, where the beamforming modes are jointly optimized with the resource allocation among multiple modes. To solve the complicated nonconvex problem, we introduce a variable substitution for facilitating the analysis and then built a tight convex approximation for the reformed problem, with which we are enabled to propose an iterative algorithm for efficiently addressing the joint optimization to a suboptimal solution. Finally, via numerical results, we validate our proposed algorithm and reveal the significant benefits of analog beamforming in aiding LAP-assisted multicasting communications.