Heterogenous Quorum-Based Wake-Up Scheduling in Wireless Sensor Networks

Shouwen Lai, Binoy Ravindran, Hyeonjoong Cho
2010 IEEE transactions on computers  
In duty-cycled wireless sensor networks, time is organized into consecutive small time slots. A node is either wholly awake in select slots (defined as slotted listening mode) or fractionally awake in every slot (defined as low power listening mode). In duty-cycled sensor networks which are not clock-synchronized, it is a non-trival problem to guarantee that two neighbor nodes discover each other within bounded latency. In this dissertation proposal, we first present quorum-based asynchronous
more » ... keup scheduling schemes for duty-cycled wireless sensor networks with slotted listening mode. The schemes organize time slots as quorum systems, and the slots in which a node will be awake are referred to as quorums. The goal is to ensure that two neighboring nodes that adopt such quorums as their wakeup schedules can hear each other at least once in bounded time slots. We propose two designs: cyclic quorum system pair (or cqs-pair) and grid quorum system pair (or gqs-pair). The cqs-pair contains two cyclic quorum systems from which any two quorums will have a nonempty intersection. The cqs-pair design provides an optimal solution in terms of energy saving ratio for asynchronous wakeup scheduling. To quickly assemble a cqs-pair, we present a fast construction scheme which is based on the multiplier theorem and the (N, k, M, l)-difference pair defined by us. Regarding the gqs-pair, we prove that any two grid quorum systems will automatically form a gqs-pair. We analyze the performance of both designs, in terms of average discovery delay, quorum ratio, and energy saving ratio. We show that our designs achieve better trade-off between the average discovery delay and quorum ratio (and thus energy consumption) for different cycle lengths. We also present rendezvous mechanisms for duty-cycled sensor networks with low power listening (LPL) mode. Our protocol is called Q-MAC, which combines quorum-based wakeup scheduling with low-power listening, to provide an asynchronous neighbor discovery, run-time configurable, and an ultra low duty cycle (i.e., 1%) solution for wireless sensor networks. Q-MAC provides configuration flexibility in duty cycle by selecting different pairwise quorums as preamble sampling schedules, which is different from the conventional approach of periodic preamble sampling as in B-MAC [1] and X-MAC [2] protocols. We show that Q-MAC can guarantee asynchronous neighbor discovery within bounded latency. Q-MAC's quorum-based wakeup scheduling is based on cqs-pair. We implemented the proposed designs in a wireless sensor network platform consisting of Telosb motes. Our implementation-based measurements further validate the analytically-established performance trade-off of cqs-pair, gps-pair, and Q-MAC. Based on these results, we propose several research directions for post-preliminary exam study. We propose to further improve the energy efficiency of quorum-based asynchronous wakeup scheduling mechanisms/protocols by asymmetric design. Another major direction is to develop cross-layer optimizations including that of routing, with such scheduling mechanisms/protocols. In addition, we also propose to develop capacity maximization solutions and support for efficient multicast and broadcast with asynchronous wakeup. iii
doi:10.1109/tc.2010.20 fatcat:2l6ec2hna5hxjgmh6qixzxapwa