Throughput optimization of cooperative UAVs using adaptive channel assignment

The wireless link represents the bottleneck in the communication of a group of cooperative unmanned airborne vehicles (UAVs). Due to the high speed of the UAVs, the nature of the environments where they are usually deployed and the possible intentional jamming that might exist, the effect of phenomena such as multipath propagation and Doppler spread is more pronounced. In this paper, we propose an adaptive channel assignment (ACA) strategy for allocating the available bandwidth, which is divided into a number of sub-channels, over a number of communications links in a network of UAVs. The proposed ACA algorithm has two main advantages over the static channel assignment (SCA) approach. First, it maximizes the overall throughput of the UAVs network and second, it significantly reduces the probability of outage in the system defined as the percentage of time the links are incapable of supporting a minimum required transmission rate that is determined by the application. The ACA approach is formulated in terms of a binary optimization problem that is solved using the branch-and-bound method. We assume that the links in the network are Rayleigh faded and we use a finite state Markov chain (FSMC) for their modeling. Using Monte Carlo simulations, we show that the proposed channel assignment approach provides a significant gain in the overall throughput and reduction in the outage probability compared to the SCA