Cooperative relaying for ad-hoc ground networks using swarm UAVs

Low cost UAVs have proved valuable in their use as sensor data collection systems in tactical situations. In this paper we examine their use as communication relays to improve range and reliability of ad hoc ground based network. MIMO based wireless communications are well known to improve capacity and reliability of point-to-point communication links. Recently, cooperation between distributed wireless nodes has been studied to exploit multi user macro diversity in an adhoc network. Application of MIMO techniques using distributed wireless nodes are also envisioned, where the cooperating nodes become the virtual antennas of a MIMO transceiver. Inspired by the recent advances in multi-UAV formation flights, we study the application of such distributed MIMO based relay schemes on a cluster of multiple UAVs. Specifically we look at the performance of distributed transmit beamforming and distributed OSTBC schemes under ideal and non ideal conditions of UAV flight. Simulation parameters are chosen based on literature study of air-to-ground propagation models. The results from our simulations show tremendous improvements in range and reliability when compared to direct ground based communication links.