Internal Node and Shortcut Based Routing with Guaranteed Delivery in Wireless Networks

  • Authors:

  • Susanta Datta;Ivan Stojmenovic;Jie Wu

  • Affiliations:

  • SITE, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada;SITE, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada;Computer Science & Engineering, Florida Atlantic University, Boca Raton, FL 33431-0991, USA

  • Venue:
  • Cluster Computing
  • Year:
  • 2002

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Abstract

Several localized position based routing algorithms for wireless networks were described recently. In greedy routing algorithm (that has close performance to the shortest path algorithm, if successful), sender or node iS currently holding the message im forwards im to one of its neighbors that is the closest to destination. The algorithm fails if iS does not have any neighbor that is closer to destination than iS. iFACE algorithm guarantees the delivery of im if the network, modeled by unit graph, is connected. iGFG algorithm combines greedy and iFACE algorithms. Greedy algorithm is applied as long as possible, until delivery or a failure. In case of failure, the algorithm switches to iFACE algorithm until a node closer to destination than last failure node is found, at which point greedy algorithm is applied again. Past traffic does not need to be memorized at nodes. In this paper we further improve the performance of iGFG algorithm, by reducing its average hop count. First we improve the iFACE algorithm by adding a sooner-back procedure for earlier escape from iFACE mode. Then we perform a ishortcut procedure at each forwarding node iS. Node iS uses the local information available to calculate as many hops as possible and forwards the packet to the last known hop directly instead of forwarding it to the next hop. The second improvement is based on the concept of dominating sets. Each node in the network is classified as internal or not, based on geographic position of its neighboring nodes. The network of internal nodes defines a connected dominating set, i.e., and each node must be either internal or directly connected to an internal node. In addition, internal nodes are connected. We apply several existing definitions of internal nodes, namely the concepts of intermediate, inter-gateway and gateway nodes. We propose to run iGFG routing, enhanced by shortcut procedure, on the dominating set, except possibly the first and last hops. The performance of proposed algorithms is measured by comparing its average hop count with hop count of the basic iGFG algorithm and the benchmark shortest path algorithm, and very significant improvements were obtained for low degree graphs. More precisely, we obtained localized routing algorithm that guarantees delivery and has very low excess in terms of hop count compared to the shortest path algorithm. The experimental data show that the length of additional path (in excess of shortest path length) can be reduced to about half of that of existing iGFG algorithm.