Research On Key Technologies Of Indoor Localization

With the rapid development of mobile internet in the 21 st century,the location service information has entered the human life as an emerging industry.And with the continuous development of social modernization and the increasing number of large-scale buildings,the demand for indoor location services by humans is constantly increasing.Especially in the special application scenarios such as fire rescue and emergency rescue,it is particularly important to grasp personal location information.Wireless local area networks(WLAN)are the mainstream indoor broadband access networks.Therefore,indoor positioning technology based on WLAN-based wireless signal is an attractive research area.Based on the difficulties and challenges in the application of indoor positioning technology,this thesis uses the indoor Wi-Fi signal for positioning system,and according to the existing indoor wireless signal propagation model — the log-normal shadow fading model.Indoor positioning is achieved without knowing the signal transmission power.The main innovations in this article can be summarized as the following five points:1?We proposed a localization algorithm based on single transmitter and single receiver scenario with the Expectation Maximum(EM)algorithm.We proposed the positioning algorithm based on the signal strength received by the signal receiver where the receiver does not know the signal transmission power.Simulation results show that the algorithm has certain advantages in positioning performance compared to the maximum likelihood algorithm.2?We derived the theoretical—Cramer-Rao lower bound(CRLB)of the estimation error for RSSI based positioning for known signal transmission power and the unknown signal transmission power case.3?We proposed two localization algorithms based on single transmitter and multiple receivers scenario.The algorithms are respectively the semi-definite programming algorithm based on Received Signal Strength Indicator(RSSI)and the semi-definite programming algorithm based on Received Signal Strength Difference(RSSD).The simulation results show that the algorithms have complete advantages over the traditional least squares positioning in performance.4?We proposed a localization algorithms based on the RSSD value combined with the path loss value.This algorithm is applied to the case where the indoor path loss changes.It does not need to measure the environmental path loss value in advance.Simulation and measurement show that the path loss value will converge it to the true value very fast,and combine with the RSSD value,the algorithm is able to achieve indoor positioning.5?We collected the wireless signal reception intensity values in the existing indoor environment to verify the performance of the proposed algorithm.