In this paper, we are interested in optimizing the delay of event-driven wireless sensor
networks, for which events does not occur frequently. In such systems, most of the energy is consumed when the radios are on, waiting for an arrival to occur. Sleep-wake scheduling is an effective mechanism to prolong the lifetime of this energy constrained wireless sensor networks by optimization of the delay in the network but this scheme could result in substantial delays because a transmitting node needs to wait for its next-hop relay node to wake up. An attempt has been made to reduce these delays by developing new method of packet forwarding schemes, where each nod opportunistically forwards a packet to the its neighboring node that wakes up among multiple candidate nodes. In this paper, the focus is to study how to optimize the packet forwarding schemes by optimization of the expected packet-delivery delays from the sensor nodes to the sink. Based on optimized delay scheme result, we then provide a solution to the central system about how to optimally control the system parameters of the sleep-wake scheduling protocol and the packet forwarding protocol to maximize the network lifetime, subject to a constraint on the expected end-to-end packet delivery delay. Our numerical results indicate that the proposed solution can outperform prior heuristic solutions in the literature, especially under the
practical scenarios where there are obstructions, e.g., a lake or a mountain, in the area of wireless sensor networks.
Energy-Efficient Packet Forwarding Scheme Based on Fuzzy Decision-Making in Underwater Sensor Networks