Distributed topology control of multiple ISAC-UAVs for mobile search teams in unknown 3-D terrains

In emergency communication scenarios, the deployment of multiple unmanned aerial vehicles (UAVs) can rapidly provide communication coverage and restore network connectivity. Though existing research has paid attention to the issue of maintaining connectivity in multi-UAV networks, there are still some problems that have not been fully addressed. This paper investigates the scenario of deploying multiple UAVs with integrated sensing and communications (ISAC) abilities to provide data collection and communication coverage services for ground mobile users in a search mission. The aim is to maximize the sum of data collected from all users and minimize the adjustment cost of the UAV network while ensuring Backbone network connectivity during the search. By modeling the effect of 3-D terrains, the simulation environment presented in this paper is more realistic. Moreover, this paper assumes that the terrain within the search area is unknown, thus the search trajectory of the mobile user is also unknown. As a consequence, centralized methods are infeasible. Accordingly, this paper proposes a distributed dynamic adjustment scheme, named QoS-Connectivity-Guaranteed Distributed Adjustment (QCDA), to ensure both quality of service and network connectivity. The efficiency of the proposed scheme is validated through simulations, and its performance in terms of data collection, communication satisfaction ratio, the number of active UAVs as well as the adjustment cost of the UAV network is better than the baselines.