Spectrum Management for MmWave Enabled UAV Swarm Networks: Challenges and Opportunities

In wireless communications, as the spatio-temporal distribution of the traffic is dynamic, the performance degradation of cellular networks becomes inevitable. Especially in catastrophic scenarios or hot-spot areas, terrestrial base stations may be poorly functioning and/or congested; thus, deploying ASCs that were carried by a UAV swarm is reasonable and cost-effective. Moreover, services such as disaster evaluation and live broadcasting require high-definition video streams, which undoubtedly need broad-band wireless transmission. To achieve this goal, the mmWave approach is introduced in the UAV swarm. However, wireless backhaul links, the mobility of UAVs and system coexistence hamper performance. In this article, we propose a novel spectrum management (SM) architecture for UAV-assisted cellular networks. Considering the special feature of mmWave, we also study SM techniques for opportunistic utilization of low-altitude UAV swarm using multi-mode radio access technologies (RATs). Both motivations and challenges of the proposed SM architecture for the UAV swarm are analyzed. To evaluate the performances of the proposed mmWave based wireless backhaul in UAV-assisted cellular networks, different SM schemes have been discussed and verified with numerical results in five typical scenarios.