Asymmetric Geographic Forwarding

Geographic Forwarding (GF) algorithms typically employ a neighbor discovery method to maintain a neighborhood table that works well only if all wireless links are symmetric. Recent experimental research has revealed that the link conditions in realistic wireless networks vary significantly from the ideal disk model and a substantial percentage of links are asymmetric. Existing GF algorithms fail to consider asymmetric links in neighbor discovery and thus discount a significant number of potentially stable routes with good one-way reliability. This paper introduces Asymmetric Geographic Forwarding (A-GF), which discovers asymmetric links in the network, evaluates them for stability (e.g., based on mobility), and uses them to obtain more efficient and shorter routes. A-GF also successfully identifies transient asymmetric links and ignores them to further improve the routing efficiency. Comparisons of A-GF to the original GF algorithm and another related symmetric routing algorithm indicate a decrease in hop count (and therefore latency) and an increase in successful route establishments, with only a small increase in overhead.