The Research On Node Localization Algorithms For WSN Based On Signal Strength Ratio

Wireless sensor network is self-organizing network which is composed with perception, calculation ability and communication ability of sensor nodes, it is associated the logical information of world with reality in the physical world, and it has a wide range of applications in many civil and military fields. In wireless sensor network application, the sensor node location information is vital throughout the whole network life. Designing high efficiency, high precision, low energy consumption localization algorithm of the node, has always been a hotspot in research of the wireless sensor network. Nodes position technology in wireless sensor network, mainly including range measurement positioning method and the distance measurement method, the distance measurement method has the advantage of technology with lower cost in practical application. It is related that localization algorithm based on centroid localization algorithm in the location accuracy and the shortage of energy based on the distance measurement in the position technology, put forward the node localization algorithm based on region partition and node localization algorithm based on signal strength geometric lines respectively.In view of the problem with low position accuracy about the centroid localization algorithm and the improved centroid localization algorithm(ICLA), this paper proposes a kind of improved region segmentation localization algorithm. Under the precondition of building the mathematical model of region segmentation, the algorithm utilizes the ratio which the unknown node received signal strength from the beacon nodes comparing with the signal strength scale factor of the region segmentation line to make sure the sub region of the unknown node. The algorithm calculates the centroid coordinate of this sub region and takes the centroid coordinate as the location coordinate of the unknown node. The simulation results show that the average localization accuracy has been improved compared with centroid localization algorithm and improved centroid localization algorithm. Under the same simulation environment, when the node communication radius is less than 20 m, the number of beacon nodes within the communication radiu of the unknown node is less, then the average position error of the three kinds of algorithms are large. The beacon node percentage is 25% ~ 35% and communication radius is greater than 25 m. The average position error of the algorithm is much smaller than the other two algorithms.In view of the problems with great average position error and high dependence of beacon node about centroid localization algorithm and APIT localization algorithm, this paper proposes a kind of signal strength geometric line localization algorithm. The algorithm through the unknown node receives the strong signal beacon nodes to calculate the signal intensity scaling factor, and according to the theory of signal strength geometric line model to calculate the eligible for positioning the signal intensity of geometric line, verify the signal intensity in different geometric line meets the requirements in the intersection point coordinate, the calculation point coordinates mean that accords with a requirement to estimate the unknown nodes location. The simulation results show that the proposed algorithm compared with centroid localization algorithm and APIT localization algorithm can effectively reduce the average node positioning error. When the measuring error signal strength is gradually increasing from 0.05 to 0.05, the average position error of the algorithm is becoming in the range of 0.05 ~ 0.1. In the same simulation conditions, the dependence of beacon nodes about the algorithm is the lowest. Due to the computational complexity of the algorithm lower, the algorithm of node energy consumption is smaller relatively.