Definition and Evaluation of Local Path Recovery Mechanisms in Wireless Sensor and Actuator Networks

In wireless sensor and actuator networks nodes can fail and the link quality can fluctuate rapidly over time. With the start of the pervasive revolution, issues like scalability and mobility must be tackled in these low-power and lossy networks. We propose and evaluate two mechanisms, path resumption and cost based multipath routing, which can help existing or new local path recovery techniques to achieve a higher success rate. With path resumption we turn the network into several virtual mountain landscapes.This will help the search for new paths if necessary. Cost based multipath routing enables the nodes to balance the load over a configured number of paths. The main objective is keeping suboptimal paths alive while keeping the maintenance overhead low. This way local recovery will achieve a higher success rate. The protocols are implemented in and simulated with ns-2 and evaluated by using WiNVis, a new wireless network visualisator. We have defined a new set of failure and mobility scenarios and we have compared the performance of both the protocols. Path resumption has a lower complexity and is less suitable for mobile scenarios whereas Cost Based Multipath Routing offers more adjustable parameters and a better mobility support.