Rendezvous Enhancement in Arbitrary-Duty-Cycled Wireless Sensor Networks

Power saving is always a critical issue in wireless sensor networks (WSNs). To reduce power consumption, utilizing duty cycling, i.e., sensor nodes switching to sleeping mode for most of the time, is commonly used in WSNs. However, sensor nodes may not be able to stay awake simultaneously to communicate with each other if their active periods are not properly scheduled. That is, a sensor node may not have a rendezvous with another node. To solve this problem, we propose a new scheduling mechanism, the Staggered Scheduling protocol (SS), in this paper. By adjusting each node´s instantaneous duty cycle in a staggered way, the proposed SS scheme can i) ensure each pair of nodes to rendezvous with each other in a limited time span, ii) produce a lower rendezvous variance when compared with existing mechanisms, and iii) allow sensor nodes to choose their target duty cycles independently. Theoretical analysis and extensive simulations have verified the superiority and feasibility of the proposed SS scheme.