A novel encounter-based metric for mobile ad-hoc networks routing

Abstract

So far the hop-count has been considered as a good metric for routing in wired and wireless networks thanks to its simplicity and effectiveness. In spite of that, the hop-count still manifests itself to be low adaptable to the environment in which nodes may be densely distributed and move at high speeds as in mobile ad-hoc networks (MANETs). Several metrics have been proposed as the replacements for the hop-count in routing of MANET such as the Expected Transmission Count (ETX) and the Expected Transmission Time (ETT). However, they only showed their outperformance in static scenarios. To deal with the mobility, some routing models employed a metric named Mobility Factor (MF) based on detecting the change of neighbour sets in a period of HELLO messages to examine the link stability before sending a packet. Nonetheless, to calculate MF values, each node needs to keep historical information of its neighbours which causes more resource usage and more computational complexity when MANETs scale up. In an attempt to find a suitable and effective metric for MANET’s routing, this paper introduces the Path Encounter Rate (PER) metric based on the concept of “encounter”. The proposed metric reflects the environment’s changes and therefore boosting the performance of routing protocols in MANETs. The throughput achieved by using the proposed metric is 30% higher than those obtained by the hop-count metric when 100 nodes move at a maximum speed of 20m/s in the area of 300×1500m2. This is a remarkable improvement compared to other metrics in mobility scenarios. Additionally, the proposed metric is much simple and has less computation compared to MF metric in terms of implementation. Though, the proposed metric and routing model in this paper is demonstrated on the Ad-hoc On-demand Distance Vector (AODV) protocol, it is generic and can be applied for various kinds of routing protocols in MANETs.