Age Matters: Efficient Route Discovery in Mobile Ad Hoc Networks Using Encounter Ages

We propose FResher Encounter SearcH (FRESH), a simple algorithm for efficient route discovery in mobile ad hoc networks. Nodes keep a record of their most recent encounter times with all other nodes. Instead of searching for the destination, the source node searches for any intermediate node that encountered the destination {\em more recently than did the source node itself}. The intermediate node then searches for a node that encountered the destination yet more recently, and the procedure iterates until the destination is reached. Therefore, FRESH replaces the single network-wide search of current proposals with a succession of smaller searches, resulting in a cheaper route discovery. The performance of such a scheme will depend on the mobility process assumed. Under standard mobility processes our simulations show that route discovery cost can be decreased by an order of magnitude with FRESH, a significant gain given that route discovery is a major source of routing overhead in ad hoc networks.