Improving Data Transmission with Helping Nodes for Geographical Ad Hoc Routing

摘要

Ad hoc networks have been extensively deployed in recent years. In such networks, obtaining a high efficiency is difficult to achieve due to mobility. Many routing approaches have been proposed to improve the performance of ad hoc networks, including table-driven and demand-driven routing protocols. Table-driven algorithms, maintain routing paths even when they are not currently in use. Hence, such algorithms typically waste large amounts of memory in storing possibly redundant data routes. By contrast, demand-driven approaches maintain routes only for so long as they are required. In an alternative approach known as geographic routing, a source only needs to know the location of the destination node and its one-hop neighbors to make a forwarding decision. Consequently, the need to establish and maintain routes between nodes is avoided. Geographic routing provides a suitable solution for large-scale and dynamic networks, and reduces link failure problems during packet routing. In wireless networks, nodes movement may cause a network partition, which hinders both data transmission and information availability within the network. Several schemes have been proposed for resolving the partition problem in wireless ad hoc networks [1, 2]. In general, the previous solutions either relied on the use of mobile devices with known trajectories or introduced additional specific mobile nodes. By contrast, this paper proposes a scheme for overcoming the problem of network partitions using only the available devices in the environment. With the scheme, the source node searches for another mobile node, designated as the helping node, which is able to meet the destination. The selected mobile node then carries the packet toward the destination. If the helping node changes its trajectory before it forwards the packet to the destination node, a handoff scheme is activated and the data packet is transferred to another mobile node for onward transmission.