A metric for routing in delay-sensitive wireless sensor networks

We present a new scheme to reduce the end-to-end routing delay in the mission-critical applications of the wireless sensor networks (WSNs) under the duty cycle model. While greedy routing in the synchronized MAC model has been studied extensively, efficient routing in an asynchronous MAC model is considerably different because the wake-up time and availability of a node along the pre-decided path are not synchronized and can be changed by many dynamic factors. The challenge is to catch this dynamic change in time and furthermore, to minimize its impact on routing decisions. We propose a normalized evaluation value ∈ at each node under the proactive model for all different paths passing through, saving the cost and delay of the reactive information model. Its measurement interprets the existence of the fastest path to the edge of the networks in a certain direction, directing any local advance greedy in the same direction. We provide a new strategy for greedy routing. First, it waits for the appearance of the expected forwarding successor; if this fails, then it will select the backup by the “first-wake-up, first use” policy to avoid a dead wait. We focus on an “everyone” model, in which each node will apply the same generic process in a fully distributed manner in order to achieve a reliable solution. By applying our approach in the networks with a uniform wake-up schedule, we illustrate the substantial improvement of our approach in both analytical and experimental results compared with the best known results.