Multiple Access MmWave Design for UAV-Aided 5G Communications

Unmanned aerial vehicles (UAVs) have tremendous potential to improve wireless network capacity, but are challenging to operate in ultra-dense networks, mainly due to the strong interference received from the dominated lineof- sight channels of the UAVs. By forming multiple highly directional beams, millimeter-wave (mmWave) communication technology allows concurrent user transmissions via beam-division multiple access (BDMA), and thus has emerged as a promising solution to mitigate interference for the fifth generation (5G) UAV communication. However, due to the limited number of beams generated in practical mmWave communication systems, conventional BDMA cannot meet the ever increasing capacity requirement. A new multiple access technique is intensely desired. In this article, we integrate mmWave communication with UAV-aided 5G ultra-dense networks, and design a novel link-adaptive constellation- division multiple access (CoDMA) technique. We discuss key challenges in efficient multiple access technique design, and then investigate design principles on new multiplexing methods and beamwidth optimization for interference management in UAV-aided dynamic networks. We further apply flexible constellation division in rateless codes, and put forward the system-level design of CoMDA with beamwidth adaptation to unleash the multiplexing gain. Finally, we show that our design can successfully enable multiple-user access within a single beam without causing any intra-beam interference while efficiently mitigating interference from adjacent beams. We also demonstrate that the proposed design is adaptive to the UAV network dynamics, and can greatly improve the system throughput.