Research On Coverage Control Algorthms In Wireless Sensor Network

As a new multi-knowledge technology, wireless sensor network has gained comprehensive attention for its extensive application prospect. In order to monitor and sense the environment and objects efficiently, covering the monitoring and sensing area fully is the first important problem. Many researchers have explored the coverage capacity, connectivity, power efficiency, accuracy of coverage problems of WSN. However, the effectiveness of the existing schemes degrades greatly in actual environment for the characters of WSN and the changeful environment. With the consideration of requirements of actual environment, this dissertation focuses on the coverage control problem in WSN, and designs more efficient coverage control algorithms from physical coverage and information coverage aspects.Based on analyzing current power-saving coverage scheme, and combining the multi-factor optimized power saving scheme and multi-level coverage power saving scheme, an efficient power multi-level coverage algorithm is presented. By measuring energy and coverage degree, it puts redundant sensor nodes to sleep mode to save energy while maintain the sensing field sufficient coverage degree with precondition of coverage and connective of WSN. Detailed simulation results and compared to existing schemes indicate that the proposed EPCA algorithm not only guarantees the network coverage degree, but also prolongs the network lifetime.Then the connectivity problem of physical irregular area coverage is analyzed. It gives the mathematical description of critical area coverage and proposes the critical area coverage heuristic optimization algorithm. By assigning different weight for critical grid points and common grid points to create the graph of sensing filed and terminal set, it establishes node-weighted Steiner tree to form critical areas coverage grids set with minimal number. Theoretic analysis proves that the proposed algorithms can fully cover all critical grids and form a WSN. Detailed simulation results and comparison with an existing algorithm indicate that the proposed algorithms obviously deploy fewer sensors with varying the number of critical grid points, sensing range, transmission range and the selection distribution probability of critical grid points.In order to deal with physical coverage and broadcasting data information forwarding problem in WSN with different transmission radius, a minimum unit disks set information coverage algorithm is proposed, which can calculate skyline set efficiently with the time complexity O ( nlogn). The proposed algorithm covers each node with minimum unit disk cover set, and the minimum unit disk cover set of a node is equivalent to its skyline set. Detailed simulation results and comparisons with existing algorithms indicate that the proposed algorithm not only covers all nodes with minimum nodes, but also prolongs the network lifetime.Finally, the description of information coverage is presented, and we prove that the information covering problem is a NP-complete problem. This paper proposes a coverage-aware data query algorithm, which maintains not only the physical coverage of WSN, but also logical data information coverage. It is executed by each sensor node to locally select the minimum number of k-neighboring nodes in order to achieve information coverage. Detailed experimental study and comparisons with existing algorithms indicate that the energy consumption of EHDQ is less, and the performance of EHDQ is much better in terms of query cost and network lifetime.