Applying Message Forwarding and Replication to Multi-UAV Message Ferry Networks

This paper presents a sparse ad hoc network where multiple mobility controlled message ferries cooperate to deliver messages for stationary and disconnected wireless nodes. Unmanned Aerial Vehicles (UAVs) are utilized as message ferries with an on-the-fly mobility decision making. The multi-hop delivery of messages is enabled by efficient message forwarding and replication among UAVs to accelerate the delivery of messages. Due to lack of global knowledge in UAVs, decisions in a UAV are made based on local observations. To this end, a signaling among UAVs occurs when they visit each other on-the-air. Through signaling, a UAV updates its view from the network and applies this information to its decision makers. Trajectory aware and priority based message replication schemes are proposed in this paper to limit the number of message replications and to decrease the delay of message delivery. The results show that the multi-hop delivery of messages in a message ferry network by message forwarding and replication among UAVs accelerates the delivery of messages comparing with a pure message ferrying scheme without any message forwarding. The proposed trajectory aware message replication scheme performs as good as the unlimited message replication scheme while decreasing the buffer length in UAVs. Moreover, the priority based message replication scheme in UAVs speeds up the delivery of high priority messages without any adverse impact on low priority messages.