I. Introduction
Routing protocol is one of the most fundamental components in wireless networks. Greedy geographic routing, as an early proposed routing principle, has attracted considerable attentions [1]–[6], and is considered to be very applicable in practical systems due to its simplicity, which is a crucial property in resource-constrained wireless networks [7], [8]. In greedy geographic routing, it is assumed that every node knows its own location, and the source of the packet knows the location of the destination. Each node simply forwards the packet to a neighbor that has the smallest distance to the destination. In a dense and uniformly deployed network without holes, greedy geographic routing often works very well and produces paths close to optimal routing.