| Summary: | 碩士 === 國立交通大學 === 網路工程研究所 === 97 === Constrained by the physical environments, the long-thin (LT) topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, an LT topology is composed of long branches of sensor nodes, where each sensor node has only one potential parent node toward the sink. Although data aggregation may alleviate excessive packet contention, constraints imposed by the maximum payload size of a packet severely limit the amount of sensor readings that may be aggregated along a long branch of sensor nodes. This paper argues that multiple aggregation nodes, termed lock gates, need to be designated along a branch to aggregate sensor readings sent from their respective upstream sensor nodes (up to the other upstream lock gate(s) and/or the end of the branch). The paper further describes an adaptive lock gate designation scheme for LT WSNs, which balances the responsiveness and the congestion of data collection, and mitigates the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time-varying sensor reading generation rates of different sensor nodes. Experimental results demonstrate the effectiveness of the scheme.
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