For wireless ad hoc or sensor networks, nonflooding, guaranteed delivery routing protocols are preferred because of limited energy. In this paper we introduce TCGR, a tree cover based geographic routing protocol for wireless networks. We assign to each node a set of short labels such that nodes are embedded in a metric space induced by one or multiple trees. Based on the embedding, we use only greedy routing to deliver packets, i.e., packets are always forwarded to the neighbor closest to the destination. Unlike many previous geographic routing protocols, we guarantee a full success ratio in finding a route to the destination, if such a route exists in the network. Moreover, each node only needs to maintain a small amount of information, which is almost surely bounded by (log ) 2 O n bits, and the label size and packet header size are also bounded by (log ) 2 O n bits. Simulations show TCGR can achieve remarkable performance in both path stretch and node load.

Abstract-The wide availability of WiFi hot-spots provides mobile users with convenient access to the Internet. However, hot-spots cover only small areas and are often operated by a local authority. A user that roams between hot-spots effectively traverses different operators and access networks. Due to deployment complexity, IP mobility is usually not supported by the mobile node or the network.In this paper we propose an approach that enables access routers to provide seamless mobility support without any changes to the mobile node or other network entities. Our approach provides a simple, flexible, and deployable framework for mobility support and scales well with the number of involved access routers. By simulation and mathematical analysis, we show that even with lower deployment requirements and less support from the network, our approach performs well in terms of routing stretch, handover latency, and signaling overhead.