Research On Indoor Positioning Technology Based On TRM

In the information time, with the further development of wireless networks and communication technology, indoor positioning become a research hotspot. However, the accuracy of existing indoor positioning systems cannot meet the growing positioning demand. Therefore, improving the accuracy of indoor positioning will continue to be primary, challenging work.Numerous studies show that indoor positioning accuracy is low mainly due to signal fading caused by serious multipath in indoor complex environment. We know that time reversal mirror(TRM) can take advantage of multipath indoor to precisely locate objectives, but the premise of high precision positioning is the need for known propagation channel model, if we can find a way to predict the indoor environmental information ahead, indoor positioning accuracy will be greatly improved. Therefore, this paper presents a method based on TRM indoor positioning method—FMM-TRM. The method combine fast matching method with the TRM, first by improving the FMM algorithm to predict the indoor environment model, and then use TRM indoor positioning technology to locate the wireless target terminal. The main work includes:(1) This paper improves three different FMM algorithms, through theory and simulation research, we analyze three different forecasting methods indoor channel model, by contrasting to select the best one to apply in indoor positioning. In electromagnetism, the parameter indoor channel model is mainly composed of the dielectric constant ? and the conductivity ? of the object. ? mainly impacts of the signal propagation time, and ? mainly affects the signal intensity values. As the FMM algorithm estimate the model by the difference between the actual TOF and the simulate TOF, which uses a time variable, so, this article will be to predict the indoor environment model through computing the distribution of?.(2) This paper combines the FMM algorithm with TRM technology to form FMM-TRM indoor positioning method. The 7.2m×7.2m whole space is divided into many uniform meshes; the span dx of each one is 0.003 m, and relative time step dt is 2.5E-12 second. Total 200 antenna surround the two dimension indoor area, 4 transmitter antenna are used to stimulate a Gauss pulses signal, these signals are used to update the indoor model iteratively, them positions are(3.60 m,3.60m),(3.60 m,5.10m),(2.28 m,2.82m),(4.86 m,2.82m) respectively. Based on this status, the positioning results of the simulation studies and comparative analysis between the FMM-TRM and TRM method under unknown environment are presented. Simulation results show that the general method of locating accuracy of about TRM is 72.19 cm, and positioning accuracy FMM-TRM method is about 2.20 cm, than conventional TRM method accuracy is improved by 30 times, greatly enhance the wireless indoor positioning performance and further validates the indoor positioning FMM-TRM method is effective and superiority.(3) This paper makes simulation analysis of the indoor positioning performance by FMM-TRM method, including stability, feasibility and positioning efficiency.FMM-TRM indoor positioning method through combining the indoor channel model prediction algorithm FMM and time reversal mirror positioning technology, play to their superiority, it not only provide the closest to the actual indoor environment channel model, but also realize accurate target positioning based on precise indoor model. So it will have high research value and reality when this method is applied to the actual positioning area.