科研成果详情

Top-k queries aim to find the top k network data, e.g., monitoring data with the highest (or lowest) rank under certain rules. It is important to many wireless sensor networks applications. This paper proposes an energy-efficient Top-k querying approach called DDT-Q. The basic idea is to use a cross-layered optimization strategy. It builds a minimal spanning tree rooted at the sink. In the tree, every node maintains a DDT (Data Distribute Table) for its subtree. DDT is used to direct Top-k queries to the appropriate nodes with influential data in the network, thus achieving optimization of query routes and selection of returned data. Every node makes use of DDT and query parameter k to decide how much bandwidth (communication slots) to allocate in an ' on demand ' fashion based on the returned data volume to its children nodes. The information in DDT is utilized here to guide optimization of the MAC layer. The results show that DDT-Q substantially outperforms the existing TAG-based approach in terms of both energy consumption and query latency under various network configurations.