Research On Refinement Algorithm Of Ranging-based Localization In Wireless Sensor Networks

Wireless sensor networks (WSNs), which integrate technologies of computer, micro-electro-mechanism, communication and sensor, is a potential research field. The wireless sensor networks consist of a large number of sensor nodes. When the sensor nodes sense the environment around, they need to know their own position to make the sensing signal useful. To locate the sensor nodes is called localization technology, which is one of the key technologies in wireless sensor networks.The paper researched on the localization technology ranging-based in wireless sensor networks and presented new refinement algorithm. There are four kinds of common ranging technology. After comprehensive consideration of cubage, power-consumption and cost of the sensor nodes, RSSI (Receive Signal Strength Indication) technology is used to measure distance between nodes. The distance-RSSI model is set up through experiments.Two new refinement algorithms are presented in the paper. Both of them are based on the ranging technology and need to locate their anchor nodes. The estimated position of the anchor nodes is used to compensate and refine the position of the unknown nodes. One is called hybrid localization-refined algorithm. To locate the unknown nodes using MAX-MIN algorithm first, then to locate them the second time using Maximum Likelihood Estimation algorithm (MLE) after distance compensation. The strategy improves the localization precision. Another one is called position-corrected refinement algorithm. After locating the unknown nodes, to compensate the position is done to increase the localization precision. The simulation and outdoor experiments show that the two refinement algorithms improve the localization precision without additional equipments.Finally, the effect of the anchor node density, the communication radius and the area of network for the localization algorithm is discussed through simulation experiments. To control these parameters in some scope, if the more the anchor node density and the communication radius are and the smaller the area of network is, then the higher the localization precision of the sensor nodes is.