Hello Protocols for Ad-Hoc Networks: Overhead and Accuracy Tradeoffs

The hello protocol (Moy, J., 1994) is a fundamental protocol for wired and wireless networks. In mobile ad-hoc networks, a hello protocol helps nodes to establish a neighbor table for link detection. If nodes exchange position information in hello packets, then it also helps them in packet forwarding decisions. In ad-hoc networks, due to node mobility, neighbor relationships change frequently. To cope with mobility, and to have an up-to-date neighbor table, nodes advertise hello packets periodically. These hello packets create congestion, which may cause control and data packets to be dropped in the network. We study the impact of hello protocols on ad-hoc networks. We present three new hello protocols which reduce network congestion. The main idea behind all three protocols is to beacon as little as possible without compromising the accuracy of the neighbor table. To evaluate the performance of our protocols and their impact on ad-hoc networks, we simulated them in GloMoSim 2.03. Our results show that the proposed hello protocols incur much lower overhead and increase the network performance compared to a periodic hello protocol, while maintaining identical neighbor table accuracy.