MAC Protocols for UAV-Aided Relaying Optical Ground-to-HAP Networks

Air-ground integrated network (AGIN) incorporating high-altitude platforms (HAP), unmanned aerial vehicles (UAV), and ground base stations (BS) has been recently rec-ognized as a promising architecture for 6G wireless networks. In addition, free-space optical (FSO) technology has shown its potential for delivering exceptionally high-speed data connections over a long distance. While previous works on FSO-based AGIN mainly focused on point-to-point connectivity, this study instead addresses the context of multiple users. This, in turn, raises concerns about the effective multiple access control (MAC) protocol design. In this study, we analyze the performance of MAC protocols, which jointly employ the rate adaptation and bandwidth allocation, in FSO-based AGIN. Particularly, we exploit the performance of different rate adaptation/bandwidth allocation-based MAC protocols for UAV-aided relaying between multiple BSs and HAP via FSO links. Performance metrics are analytically obtained based on Markov models, including frame loss probability, system throughput and average delay. Numerical results offer insights for properly choosing MAC protocols for FSO-based AGIN towards 6G wireless networks.