Research And Implementation Of Localizationalgorithms Based On Wireless Signals

With the rapid development of the wireless communication technology and sensor technology, location-based service becomes one of the most potential mobile Internet businesses, and the location information acquisition attracts more and more research interests. People urge to get the accurate position of the mobile terminal instantly. As the connection, integration and interdependence between communication and location are even closer, localization becomes easy with the help of the wireless communication technology and parameters measurement. Wireless localization is to calculate the position of the unknown nodes by accessing the network parameters of the signals between the unknown nodes and the anchor nodes in the wireless network. Wireless localization technology can enhance the positioning performance when combining the short-ranged communication technology with the localization algorithms. Generally, the existing localization algorithms can be divided into two categories:range-based algorithms and range-free ones. The range-based algorithms first measure the distance between nodes based on the radio signals, then calculate the location of the unknown nodes, while the range-free algorithms mainly depends on the information such as network connectivity.In this paper, the prons and cons of classic localization algorithms are first analyzed and compared via simulations. Based on the performance analysis, suitable algorithms are employed in our wireless localization system testbed. Then two improved schemes with the geometrical constraints are proposed, which include the boundary constraint-based one and equivalence constraint-based one. The boundary constraint means the difference of the two measured distances is under constraint, while the equivalence constraint refers to the equivalence among the four measured distances.Finally, a wireless localization testbed is desgined and its performance is verified, which is based on the short-ranged communication technology and the localization algorithms including trilateration, LSE, MLE, fingerprint localization algorithms. The essential modules of the testbed include the data acquisition module, data upload and download module, data storing module and calculation module. The testbed not only valuates the location algorithms to output the data used for the next stage and guides the research direction, but also verifies the enhanced performance of the two proposed schemes.