| In the numerous applications of wireless sensor network, users are often interested in the sensory data in a target area. For example, a user wants to get a group of relevant data, like temperature or humidity, of a planting area. Presently, the query algorithm of relevant wireless sensor network (WSN) area can be divided into two main kinds:the tree-based algorithm and the algorithm based on route, and the former one is vulnerable to changes of the network topology. In this paper, researches are done on the basis of route-based query algorithm to collect sensory data in a target area, and the position of each node in the area can be gained by the GPS technology. Details are presented as follows:1. The existing window query algorithm (IWQE) is improved. In the member nodes of the present IWQE algorithm, there exist problems such as unnecessary data transmission or non-best cluster head selection, and the IWQE algorithm will be suspended when the network is empty, because the next query node cannot be found. Therefore, this paper puts forward an improved IWQE algorithm, namely IWQE-Ⅱ. IWQE-Ⅱ algorithm uses double cluster heads in the data transmission process, that is, chooses a cluster head (query node) which is close to the current node to transmit data, in this way, the transmission energy consumption can be reduced and the data collecting can speeded up. Meanwhile, IWQE-Ⅱ algorithm can provide two different kinds of solutions according to different empty problems.Simulation experiments show that IWQE-Ⅱ algorithm has better performance than IWQE algorithm in such aspects as query quality and energy consumption reduction, and it will not be interrupted as frequent as IWQE algorithm when the network has sparse nodes.2. A new regional GQE query algorithm is proposed. The application environment is:target area with dense sensor nodes; sensory data in target area are collected actively. In each query, the proposed algorithm considers the data are the same which are collected from the sensor nodes in the same virtual gird, so there is no need to collect data from all sensory nodes in the target area. Therefore, only one node needs to be remained as the active one, while the other nodes can transfer into other states. And the active node is selected according to such related factors as the remaining energy of nodes. The concept of’block’is proposed in the GQE algorithm, a block is composed of several virtual grids, and to the external sensor nodes, a block is just like a closed structure, after the external nodes transmit the query information into the block, collected data will then be transmitted outside; Internally, when the query information is passed into the block, merged results of internal sensory data will be passed to the external nodes. Finally, the transmission lines between blocks are analyzed and designed within the target areaSimulation results indicate that the GOE algorithm has certain advantages to IWQE and IWQE-Ⅱin total energy consumption, because it does not need to collect sensory data of all the nodes. What’s more, repeated experiments show that the energy consumption distribution of each node is balanced in the network, which is beneficial to prolong the survival period of the network. |
