Unmanned aerial vehicle (UAV) base stations (BSs) can be a promising solution to provide connectivity and qualityof-service guarantees during temporary events and after disasters. In this paper, we consider a scenario where UAV-BSs are serving a large number of mobile users in a hot spot area (e.g., in a stadium). We introduce non-orthogonal multiple-access (NOMA) transmission at UAV-BSs to serve more users simultaneously considering user distances as the available feedback for a user ordering during NOMA formulation. With millimeterwave transmission and multi-antenna techniques, we assume that UAV-BS generates directional beams and multiple users are served simultaneously within the same beam. However, due to the limitations of physical vertical beamwidth of the UAV-BS beam, it may not be possible to cover the entire user region at UAV altitudes of practical relevance. During such situations, a beam scanning approach is proposed to maximize the achievable sum rates. We develop a comprehensive framework over which outage probabilities and respective sum rates are derived rigorously and we investigate the optimal operational altitude of UAV-BS to maximize the sum rates using our analytical framework. Our analysis shows that NOMA with distance feedback can provide better outage sum rates than orthogonal multiple access. Index Terms-5G, drone, HPPP, mmWave, non-orthogonal multiple access (NOMA), stadium, UAV.
Reference REF introduces the NOMA transmission at an unmanned aerial vehicle BS for serving more users simultaneously.
Non-Orthogonal Multiple Access for mmWave Drone Networks With Limited Feedback
IEEE Transactions on Communications
IEEE Transactions on Communications
Computer Science Mathematics