An airborne communication relay scheme for IEEE 802.11 WLAN based network

A terrestrial based communication system cannot guarantee line-of-sight for node mobility and dynamic terrestrial constraints. To solve problems, airborne communication relay, the use of unmanned aerial vehicle (UAV) as a relay node (RN) has been studied. The RN provides communication relay between disconnected networks. However, to the best of our knowledge, suitable MAC for airborne communication relay has not been studied. In airborne communication relay, two transmission phases are needed: 1) a transmitter node to the RN and 2) the RN to a receiver node. When adapting current 802.11 WLAN to airborne communication relay, contention based CSMA/CA MAC increases latency for two transmission phase. Because of increase of latency, the RN cannot relay the packet frame quick enough and continuous transmission failure occurs buffer overflow in the RN. In this paper, we studies problems when adapting 802.11 WLAN to airborne communication relay and proposes suitable MAC protocol for airborne communication relay, called a frame relay CSMA/CA (FR-CSMA/CA). The FR-CSMA/CA skips contention in relay phase to reduce latency and to solve buffer overflow in the RN. Moreover, the FR-CSMA/CA only changes parameters of the RN, so which improves performance of the current CSAM/CA scheme keeping compatibility with current communication system.