Research On Coverage Algorithm In Wireless Multimedia Sensor Networks

With high-speed development of wireless communications, electronic chip and sensor technology, wireless sensor network s(WSNs) technology has been rapid development. Wireless sensor networks has developed from traditional omni-directional sensor to directional sensor development, while the object of WSNs collect, transmit and process extended from simple environment data(e.g temperature, humidity, light intensity, etc) to sound, image and video streaming, which is wireless multimedia sensor networks. The initial deployment way of wireless multimedia sensor networks mainly is large-scale and random, so it’s easy to cause node uneven distribution. The research of wireless multimedia sensor coverage control is under the condition of ensure network’s QoS(Quality of Service) to attain the purpose of coverage range’s optimal by use coverage enhancement strategy. Coverage control algorithm make an important significance in information acquisition, environment sensing and improve network’s QoS.To improve PFCEA(Potential Field based Coverage-Enhancing Algorithm), this thesis proposed a kind of OPFCEA(Optimization of the Potential Field based Coverage-Enhancing Algorithm for wireless multimedia sensor networks) on the basis of the existing directional sensing model. Firstly, in PFCEA, the node which at the target area boundary is only affected by the repulsion of the nodes inside the region and their sensing range will deflection outside the target area under the guidance of repulsion. The kind of virtual node introduced by OPFCEA which proposed by this thesis is used to provide boundary nodes with virtual repulsion and lead it to change the sensing direction to cover the target area as much as possible, and this kind of node is deployed outside the monitoring area and close to boundary. Secondly, a kind of adaptive rotation angle iteration formula given by OPFCEA:the value of the coverage ratio becomes one of the fectors that affect the angle of rotation, so the rotation angle could be large in early stage of the algorithm while coverage ratio increased fester and be small in last stage of the algorithm while coverage ratio increased slower; OPFCEA also gives a solution aim at the problem of nodes’ frequently rotate back and forth in PFCEA’s late stage:when the area coverage ratio increases to a certain value and the growth rate is less than the threshold, only calculate the resultant force but don’t rotate for these nodes to reduce the frequent rotation. Finally, this thesis uses MATLAB to simulat and analyze, the simulation results are carried to show the feasibility and effectiveness of OPFCEA.Although OPFCEA increased some algorithm complexity, but it improved the coverage ratio of the monitoring area and reduced the energy consumption of the nodes during the process of cover enhancement relative to PFCEA, and it also helps to improve the QoS.