Route update and repair in wireless sensor networks

In wireless sensor networks, the multihop routes between sensors and sinks (data collectors) suffer breakage or damage because of the movement of targets and sinks, or the power exhaustion of some sensors. An efficient route maintenance and update protocol should give attention to both route rediscovery overhead and route optimization. In most flooding based routing protocols, route discovery/rediscovery packets are broadcast omni-directionally, which causes significant communication overhead as well as wireless channel contention. Query localization (QL) protocol (Castenada, R. et al., ACM/Kluwer Wireless Networks Journal, vol.8, no.2, p.137-51, 2002) limits the broadcast of route rediscovery packets within the local region of the old routes. However, as new routes formed under QL have to share most parts with old routes, route optimization is penalized. We propose to update the route by using the information of the old route, but at the same time, select a new route not necessarily overlapping the old one. This virtue is especially important to route-wide update cases, such as continuous movement of targets and sinks, and renovation of worn-out routes. Simulations show that, our new protocol always builds a fresher and better route with a very low control overhead.