## 3 \(l\)-\(k\)-Nearest-Neighbors Query Processing
### Algorithm for Query Dissemination
(**a**) Query latency when \(l\) is 10 m; (**b**) Query latency when \(l\) is 20 m; (**c**) Query latency when \(l\) is 30 m.

\(l\)-\(k\)NN when \(l\) is larger than \(r\). These results occur for similar reasons as for the query latency results. When \(l\) is larger than \(r\), DIKNN disseminates the query messages to more sensor nodes than \(l\)-\(k\)NN does, and _vice versa_. ## 5 Conclusions

In this paper, we proposed a solution, the \(l\)- \(k\)NN, for the novel spatial query problem in mobile sensor networks. The query result implies well scattered objects nearest to the area of interest. The \(l\)- \(k\)NN approach can be used in most \(k\)NN applications if we want to get well distributed or wide coverage of the \(k\)NN result. \(l\)- \(k\)NN divides the search space into several track-sectors in which all sides are equal to or larger than the distance constraint \(l\). By selecting Q-nodes in alternating track-sectors, we have guaranteed \(l\) distances between any two Q-nodes. To maintain the \(l\) distance tightly, we adjusted the central angles and radii of the track-sectors. We also adopted parallel computing for query dissemination to reduce query latency. Through comprehensive experiments, we showed that the proposed algorithm exhibits superior performance compared with a post-processing based method using the \(k\)NN query in terms of energy efficiency, query latency, and accuracy. ## Acknowledgments

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2012R1A2A2A01047478). ## Author Contributions

[PERSON], [PERSON], and [PERSON] conceived the idea for this work. [PERSON] and [PERSON] designed and performed the experiments. [PERSON] and [PERSON] wrote the paper. All authors read and approved the final version of the paper. ## Conflicts of Interest

The authors declare no conflict of interest. Figure 10: Comparisons of energy consumption with various values of \(l\) and \(k\). (**a**) Energy consumption when \(l\) is 10 m; (**b**) Energy consumption when \(l\) is 20 m; (**c**) Energy consumption when \(l\) is 30 m.

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