Research On Environment Adaptive Wireless Location Algorithm Based On Virtual Reference Node

The wireless location technology is to determine the position of the object by measuring the parameters of the radio waves, based on specific algorithms. It includes infrared, ultrasonic wave, Bluetooth, radio frequency identification, ultra-broadband, Wi-Fi, ZigBee, etc., initially is needed for voyage navigation. It has been used in mobile phone users, mine personnel positioning disaster site, search and rescue personnel, and the container transportation tracking, vehicle navigation extensively. It draw much attention in recent years due to the growing business needs of wireless location, and the development of robot applications, special merchandise management. Currently, according to whether need to measure distance between nodes, location algorithm can be divided range-based and range-free two classes. Rang-based algorithms mainly include TOA (Time of Arrival), AOA (Angle of Arrival), TDOA (Time Difference of Arrival), and RSSI based, etc. These methods are mainly by measuring the inter-node distance or angle information, and calculate the unknown node position by triangulation or maximum likelihood estimation. Range-based algorithm requires special hardware, so that the disadvantage of increasing the cost and volume of sensor nodes, thereby limiting its availability. Range-free algorithms only rely on network connectivity information, without additional hardware. So they have certain advantages in terms of cost and power consumption than range-based algorithms. Usually range-free algorithms include centroid algorithm, APIT algorithm, DV-hop algorithm and DV-distance algorithm.Traditional location algorithms based on RSSI, whether range-based or range-free will it will be influenced by changes of the environment. Changes of environment will result in decrease of positioning precision. Whenever there are serious changes of environment, it will inevitably get significant loss of positioning accuracy, even crash. To reduce the influence cased by environment changes, either using the real-time reference measurement point, or the introduction of more measuring stations. This will increase system cost and complexity. Moreover, a large number of real-time reference point can also cause a signal interference between each other. As a result, such a positioning solution is not possible in the case of the weather or the environment is constantly changing. To get rid of this situation, our proposal puts out Virtual Reference point based Environment-adaptive Wireless Localization Algorithm, VREALA.Our proposal is based on the virtual reference point, range-free algorithm. We learned centroid localization algorithm, and give out an improved weight value selection approach, to improve the positioning accuracy of the system. We focus on getting environmental adaptive without any additional equipment. We judge the accuracy of the positioning, so we get the credibility for position result. After that the history positioning data could become a virtual reference point. The virtual reference point can be updated when the environment takes changes, so system will achieve the effects of the environment adaptive, to ensure the positioning accuracy in the long time. It’s an environment-adaptive positioning system without increasing system overhead.VREALA has many innovations:1. The way to create and update the virtual reference points in the system.2. Improved weight calculation method to optimize the positioning accuracy.3. Estimate localization error range, given a single localization credibility.4. Achieve environment-adaptive without increase any additional equipment.