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. Many existing geographic routing protocols fail to consider asymmetric links during neighbor discovery and thus discount a significant number of potentially stable routes with good one-way reliability. This chapter provides a detailed overview of a number of location-aware routing protocols that explicitly use asymmetric links in routing to obtain efficient and shorter (low latency) routes. An asymmetric link routing protocol, called Asymmetric Geographic Forwarding (A-GF) is discussed in detail. A-GF discovers asymmetric links in the network, evaluates them for stability (e.g., based on mobility), and uses them to improve the routing efficiency.
