Signal strength based link sensing for mobile ad-hoc networks

Mobility causes frequent link failures in ad-hoc networks. This results in a severe degradation of performance specially in case of high mobility of nodes. This is because the routing protocols for ad-hoc networks are not equipped to handle high mobility. In this paper, we have presented a new link management algorithm to locally manage links. This new mechanism is based on signal strength measurements. Researchers over the years have presented approaches which use signal strength measurements but their focus has been on re-active protocols while our algorithm is aimed at pro-active protocols. Pro-active protocols are used since they provide greater flexibility to take advantage of the mesh configuration. We develop the hysteresis mechanism provided by OLSR, based on hello packets, to include signal strength measurements. The mechanism in OLSR uses Hello packets received/lost to decide to establish link or not. The problem with this approach arises when there is high mobility in which case the time to break the link and use a new path becomes significant. To overcome this, we propose to use signal strength to determine if the link-quality is improving or deteriorating. This combination of the two mechanisms, makes the link management more robust and also helps in anticipating link breakages thereby greatly improving performance.