“Direction” Assisted Geographic Routing for Mobile Ad Hoc networks

— In Geographic Routing protocols (e.g. GPSR), a node makes packet forwarding decisions based on the coordinates of its neighbors and the packet’s destination. Geo-routing uses greedy forwarding as a default; if this fails (e.g. the packet is trapped in a dead end caused by holes and/or obstacles), a recovery scheme based on perimeter routing is invoked. This however often leads to degraded performance. In this paper, we present a hybrid routing scheme called Geographic Direction Forwarding Routing (Geo-DFR), which features efficient recovery from dead ends. Geo-DFR integrates on demand, table driven routing with geo-routing. During the data transfer, periodic routing advertisements from the destination help to track node motion and to update/maintain a feasible direction to the destination. Direction Forwarding in Geo-DFR is designed to complement and even replace perimeter routing in dead end recovery. With the help of a local coordinate system (e.g., GPS or virtual coordinate system), a node derives the direction of the arrival of the advertisements. A packet is first forwarded to the neighbor which yields the most progress towards the destination, i.e., greedy forwarding. If greedy forwarding fails, the packet is “directionally” forwarded to the “most promising” node along the advertised direction, i.e., direction forwarding. Moreover, the direction can be used proactively for “early dead end detection” to decide which forwarding scheme should be used to avoid getting stuck, which is opposed to GPSR in which perimeter routing is applied only after greedy forwarding fails. Through simulation experiments we show that Geo-DFR substantially improves the performance in large, mobile network scenarios.