Robust Ad Hoc Routing for Lossy Wireless Environment

Random loss in wireless ad hoc networks derives from two main causes: lossy wireless links and node mobility. Packet loss and link breakage can dramatically degrade the performance of any network protocol thus making routing in mobile ad hoc networks extremely challenging. In this study we focus on applications that exhibit mobility and random packet loss. Possible scenarios include search and rescue, urban homeland defense, small unit battlefield operations, and car to car network gaming. We explore the robustness of the routing solutions in regards to speed (up to vehicular ranges), random packet loss, and traffic load. Traditional routing protocol candidates are proactive, reactive and location-assisted (i.e., geographic) such as OLSR, AODV and GPSR. However, the performances of each protocol varies significantly with mobility and random loss shown in the paper. In our approach we seek to a hybrid solution AODV-DFR (AODV with Directional Forward Routing) that combines the positive aspects of previously proposed schemes. AODV-DFR utilizes the positive features of both proactive and reactive routing schemes, in addition, it borrows the greedy forwarding concept found in geo-routing. This allows for AODV-DFR to automatically find good candidates for packet forwarding in case of route breakage. Greedy forwarding here takes the form of "directional forwarding". Each node keeps a gradient direction toward the destination. This direction is dynamically refreshed based on periodic, proactive updates issued by the destination. Simulation studies show that AODV-DFR outperforms conventional protocols and previous hybrid routing solutions across a wide range of network characteristics.