Cluster-based semi-asynchronous power-saving protocols for multi-hop ad hoc networks

Existing power saving (PS) protocols for mobile ad-hoc networks (MANETs) can be categorized into synchronous and asynchronous ones. The synchronous PS protocol can not be applied to a multi-hop MANET, because it will cause three problems, namely clock synchronization, neighbor discovery, and network partitioning. Although asynchronous solutions are attractive, yet, the cost is high as opposed to synchronous protocols. Hosts in asynchronous protocols need to keep awake for longer time, so as to discover asynchronous PS neighbors. Besides, a broadcast message has to be sent multiple times if a sending host's neighbors wake up asynchronously. To conquer the deficiency of asynchronous PS protocols, we propose several cluster-based semi-asynchronous PS protocols for multi-hop MANETs. The basic idea is to cluster neighboring hosts such that synchronous PS protocols can be adopted within individual clusters, and conserving a lot of energy. Two asynchronous schemes are provided in the inter-cluster level, including SNR-probability-based and location-based schemes. Simulation results show that, the proposed semi-asynchronous approaches outperform the asynchronous PS protocols when applied to a multi-hop MANET.