Research Of Minimum Delay Routing In Duty-cycled Wireless Sensor Networks

A wireless sensor network consists of a large number of cheap and tiny sensor nodes which form a multi-hop network by wireless communication and carry out surveillance for target area.Routing is one fundamental but important function in wireless sensor networks. It con-nects the sensor nodes into a whole network and provides a transmission path between the source and the destination. Generally, sensors are battery-powered devices and their battery cannot be replaced. Therefore, sensor nodes often use duty-cycling mode to save their energy, i.e., they switch between active mode and sleep mode, and only work (sending or receiving data) for a fraction of time. The duty-cycling mode saves nodes’ energy but bring other issues such as sleeping (or waiting) latency and time-dependent routing, which makes routing design more challenging.In this paper, we study routing in duty-cycled wireless sensor networks. We first pro-pose a distributed routing algorithm to find the minimum-delay routes at any time from all nodes to the sink. In this algorithm, each node updates its routing table according to the routing information of its neighbors, and the routing table eventually converges to the optimal values including the minimum delay and corresponding next hop at any tame.We further propose a distributed routing algorithm which aims to minimize the ex-pected latency of routes and takes the link quality and contention degree into account. Compared with our former algorithm, this algorithm improves in two aspects. First, it introduces the link quality into routing design as the link quality may vary from time to time, and the delivery ratio is used to measure the link quality. Second, it introduces contention degree into routing design as burst traffic may cause severe contention, and the mechanism of balancing contention is used.Finally, we carry out extensive simulations and compare the performance the two pro-posed algorithms in terms of the completion time of routing convergence, the comple-tion time of convergecast, and packet delivery ratio.