Wireless sensor networks have been used in many mobile applications such as wildlife tracking and participatory urban sensing. Because of the combination of high mobility and low-duty-cycle operations, it is a challenging issue to reduce discovery delay among mobile nodes, so that mobile nodes can establish connection quickly once they are within each other's vicinity. Existing discovery designs are essentially pairwise based, in which discovery is passively achieved when two nodes are prescheduled to wake up at the same time. In contrast, this work reduces discovery delay significantly by proactively referring wake-up schedules among a group of nodes. Since proactive references incur additional overhead, we introduce a novel selective reference mechanism based on spatiotemporal properties of neighborhood and the mobility of nodes. Our quantitative analysis indicates that the discovery delay of our group-based mechanism is significantly smaller than that of the pairwise one. Our testbed experiments using 40 sensor nodes and extensive simulations confirm the theoretical analysis, showing one order of magnitude reduction in discovery delay compared with legacy pairwise methods in dense, uniformly distributed sensor networks with at most 8.8 percent increase in energy consumption.
Bibliographical noteFunding Information:
This research was supported in part by the US National Science Foundation (NSF) grants CNS-0845994, CNS-0917097, NSFC grants 61228302, 61373091, 61273361, 111 Program under grant B07031, grant SUTD SRG ISTD 2010 002 and SUTD-ZJU/RES/03/2011. A preliminary version of this paper was presented in 2012 IEEE SECON in Seoul, South Korea, and appears in the conference proceedings. Jiming Chen is the corresponding author.
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- Wireless sensor networks
- group-based mechanism
- proactive discovery