中文摘要：

针对Multi—Radio Multi—Channel传感器网络中链路服务质量和信道冲突等问题，提出并证明了基于缓存和信道切换的数据查询问题是一个NP完全问题．根据数据流守恒和链路一信道等约束条件，建立线性规划方程，得到该问题的最优解模型，并提出了一个多项式时间的近似算法——贪心新覆盖数据算法．该算法采用动态规划策略最小化缓存节点将单位数据包传输到查询节点所需要的路径时延，再贪心选择其具有最小路径时延的缓存节点，收集其新覆盖数据．理论分析和实验结果表明，提出的方案能有效地减少数据收集时延，提高数据查询效率．

英文摘要：

Due to the nature of multi-radio multi-channel wireless sensor networks, such as the quality of service of the links, channel conflict etc. , we investigated the problem of data query based on data cache and channel switch, and proved it to be an NP-complete problem. Firstly, we constructed a LP equation based on the data flow conservation and link-channel constraint etc. to formulate the problem, then designed a polynomial approximate algorithm. The algorithm used dynamic programming strategy to minimize the delay of unit data packet transmission from cache nodes to the query node, greedily chose a cache node with the smallest delay of unit data packet transmission, and collected the new covered data packets. Theoretical analysis and experimental results indicate that the proposed algorithm can reduce the communicate delay and improve the efficiency of query effectively.