QoE Maximization for Multi-Antenna UAV-Enabled Video Streaming

Unmanned aerial vehicle (UAV) is a promising solution to flexibly provide video service for scenarios with temporary traffic. Compared with single-antenna UAV, multi-antenna UAV improves the spectrum efficiency for video transmission. In this paper, we investigate a multi-antenna UAV-enabled streaming system for providing video service to multiple ground users (GUs) simultaneously. To fully utilize the spatial multiplexing gain brought by multiple antennas, we aim to maximize the minimum quality of experience (QoE) for GUs through joint optimization of video playback rate and transmission scheduling as well as UAV trajectory, where the tradeoff between video quality and video playback fluctuation are also taken into account. The optimization problem is formulated as a challenging mixed-integer nonlinear optimization problem. A double-loop iterative algorithm is proposed to obtain a suboptimal solution by employing penalty block coordinate descent (P-BCD) technique. To reduce the influence induced by violation of equality constraint, we update the penalty parameter in the outer loop. In the inner loop, we solve the penalized problem with given penalty parameter through BCD and ConCave-Convex procedure (CCCP) as well as successive convex approximation (SCA) techniques. Simulation results illustrate remarkable performance gains of our proposed scheme compared to benchmarks, which also reveals the tradeoff between quality and playback fluctuation of video.