Zigzag: Local-Information-Based Self-Optimizing Routing in Virtual Grid Networks

In this paper, we present a local-information-based self-optimizing routing protocol Zigzag in virtual grid networks. A virtual grid network is obtained by virtually dividing a wireless network into a grid of geographical square regions called cells, and is used in MANETs and sensor networks to reduce energy consumption. A single node is selected as a router at each cell and inter-cell communication is realized by using the routers. Other nodes in the cell have no responsibility for inter-cell communication and can become inactive to save energy consumption. We consider maintenance of an inter-cell communication path to a destination node from its source node. When the destination node moves to a cell next to the current one, the path can be simply updated by extending it to the next cell. But, if the destination node moves around the network, the path becomes redundantly long and needs to be shortened. In this paper, we propose a self-optimizing routing protocol Zigzag in virtual grid networks, which can transform any given inter-cell path to a shortest (or minimum-hop) one by repeatedly applying local updates on the path. The routers locally and asynchronously update the path based only on local information and require no global information of the path such as the locations of the destination and the source nodes. We also show that the convergence time to a shortest path from any given path P is O(|P|) in the synchronous execution where |P| is the length (or the number of hops) of P.