A Dynamic TDMA Scheme for UAV Based Relay in Combat Net Radio Networks

Ground tactical networks are often limited in their operations when the line of sight (LOS) is not guaranteed. To overcome this limitation, airborne relay communications using unmanned aerial vehicles (UAVs) are a possible solution. In airborne relay communication, it is important to reduce relaying delay because the airborne relay communication is extended to two-hop communication unlike the conventional communication environment. In this paper, we proposed a dynamic time-division multiple access (DTDMA) scheme based on time mirroring to reduce relaying delay in airborne relay communication and allow multiple nodes to access the network effectively. The proposed scheme also performs efficient resource allocation and supports seamless voice communication in order to accommodate the military communication environment where nodes join and leave frequently. Proposed scheme applies the time mirroring scheme to DTDMA. Time-mirroring is a scheme in which a relay node that receives a packet from a source node relays a packet to a destination node without any additional processing. The proposed scheme designates two-timeslots as one mirroring slot to minimize the delay caused in the slot assignment process of the relay node. Slot assignment is accomplished by dividing the idle mirroring slot into a number of mini-slots and allowing the node to randomly access the mini-slot. The simulation shows that the proposed scheme can significantly reduce relaying delay and support seamless voice communication.