中文摘要：

针对MANET环境中带宽有限、能量有限、存储有限和链路频繁的断接性等特点，提出了基于缓存的移动数据查询问题，证明该问题是NP完全问题，并给出一个多项式时间的近似算法，即最大节点新覆盖数据算法MD．该算法采用贪心策略，查询新覆盖数据量最大的节点，减少了查询次数，并最大限度地减少了网络中的传输时延．然后在MD算法的基础上，同时考虑了节点新覆盖数据量和链路服务质量问题，提出了一种改进的高效的启发式算法，即基于最大节点DD值的算法MDD，有效地减少了能量消耗，最小化数据传输时延，提高了网络的吞吐量．理论分析及实验结果表明提出的数据查询算法能够充分利用缓存节点的数据信息，较好地完成数据查询工作，有效地减少数据收集时延，提高查询效率．

英文摘要：

commumca frequent di Aiming at the nature of mobile Ad-Hoe networks, such as self-organization, limited tion bandwidth, multi-hop communication, limited energy, limited storage and the sconnection of the links, etc, a problem of mobile data query based on caching is formulated and proved to be a NP-complete problem. Then a polynomial approximate algorithm which is called MD is given to solve the problem. The MD algorithm uses greedy strategy to query cache nodes which store the largest amount of new data packets, so as to reduce the number of query and minimize the network transmission delay. According to the approximate algorithm for mobile data query, another algorithm is proposed based on the max ratio of new data packets and unit communicate delay of cache nodes, called MDD. It not only takes the number of new data packets into account, but also considers the quality-of-service of the links. This algorithm can improve the efficiency of query, minimize network data transmission delay, reduce energy consumption and improve network throughput. Theoretical analysis and experimental results indicate that the proposed algorithms can make full use of the data of cache nodes, complete data query better, reduce data transmission delay, as well as improve the efficiency of query efficiently.