Using geographical coordinates to attain efficient route signaling in ad hoc networks

Flooding of route requests or link states is a necessity in many routing protocols for mobile ad hoc networks (MANET), and several mechanisms have been devised to make flooding more efficient; however, all flooding approaches to date are such that the number of neighbors each node must use to relay a flooded packet grows as the node density increases. A new method, called ORCA (On-demand Routing with Coordinates Awareness) is introduced for the dissemination of route requests in MANETs. The selection of relaying nodes at each node in ORCA is done by computing the shortest Euclidean Distance from all neighbors of the node to four polar points located in the transmission range of the node. We prove that ORCA guarantees the coverage of all nodes in a connected MANET, and that the number of relays for each node is at most six. ORCA is compared with representative routing protocols, namely AODV, OLSR, LAR, and THP. The simulation results in networks of 200 and 250 nodes show that ORCA incurs the smallest routing load while attaining average delays and packet delivery ratios that are comparable to or better than those obtained with the other four routing protocols.