A Spiral Curve Based Chord Enabling Resource Sharing for Wireless Mesh Networks: A Location Awareness and Cross-Layering Approach

Abstract

The contradictions created by the differences in mass P2P data and transfer capability of wireless networks, and mismatch of overlay network topology and physical network topology are the main barriers hindering the implementation of P2P resource sharing in wireless multi-hop networks. This paper investigates the problem of enabling P2P resource sharing in WMNs with two-tier architecture. SpiralChord, the DHT approach implemented through routers in the upper tier, is proposed to address the major problems of wireless resource sharing — how to efficiently find resources currently available and reduce redundant messages as much as possible. SpiralChord uses an ID assignment technique to integrate location awareness with cross-layering. Location awareness aims at alleviating mismatch in physical network topology and overlay network topology, and it is designed to map neighboring routers to close-by IDs in the logical ring. Cross-layering aims at speeding up resource lookup operations in the application layer by exploiting the information that is available at the MAC layer, and it tends to be more effective when physically neighboring routers have faraway IDs in the logical ring. An ID assignment strategy based on spiral curve is proposed to meet the contradictory requirements of location awareness and cross-layering, mapping a peer's neighbors in the overlay network to peers which are its physical neighbors and distributing the remaining physical neighbors as widely as possible in the overlay network. In addition, a mobility management mechanism is proposed to address the adverse effect of the movements of clients in lower tier on resource sharing. A client is assigned a managing router to take the responsibility for the location of the client. Simulations show SpiralChord is more effective in reducing message overhead and increasing lookup performance than Chord, and mobility management for mobile clients performs well at reducing message overhead caused by mobile clients in SpiralChord.