Abstract: A Sampling Algorithm for Median Query (SAMQ) based on Wireless Sensor Network (WSN) was proposed. In SAMQ, each node in WSN created a fresh sample summarizing its own observed values and the received values from children nodes, and then broadcasted its subsequence to the parents. Finally, these samples were combined to a single sample in the root node whose data structure was far smaller than the size of the whole data set. The approximate value for median query could be obtained from the sample quickly. A shared channel was used to reduce packet loss. Analytical and experimental results show that the proposed algorithm has the advantages of low power consumption, small error range, and is able to significantly prolong network lifetime.

Key words: Wireless Sensor Network (WSN), median query, sampling algorithm, aggregate algorithm

摘要： 提出一种基于无线传感器网络的中位数查询抽样算法SAMQ。在SAMQ中，网络中各节点将分布式产生各自的样本集，然后将样本集聚集传递后汇集到根节点形成全网的样本集，最后使用这个远小于全网数据集规模的、可用于代表全网数据集结构的样本集，迅速获得中位数查询的近似结果，从而无需将各传感器节点的所有数据都传输至根节点，同时采用了共享无线通道的方式进行通信，减少了网络数据丢包。理论分析和实验结果显示该算法功耗低、误差较小，能有效地延长网络的生命周期。

关键词: 无线传感器网络, 中位数查询, 抽样算法, 聚集算法