| Indoor positioning system plays more important role in today’s society. Ultra-wideband (UWB)technology in solving the problem of non-line-of multipath propagation has the unique advantages,at the same time it also has considerable advantages in device deployment cost, power consumptionand so on. Therefore ultra wideband (UWB) has a very high value as a major indoor positioningsystem technology. In this thesis, UWB technology is used as the primary means of indoorpositioning system technology.UWB indoor positioning system is mainly divided into two parts: ranging part and precisepositioning part.The main work of the thesis is as follows:There are generally four methods in ranging part, which are based on the received signalstrength indication(RSSI), based on the time of arrival(TOA), based on the angle of arrival(AOA)and based on the time difference of arrival. By analysis and comparison of four above methods ofcharacteristics, this thesis selects mixture of RSSI and TOA two methods to complete the rangingdistance. By setting rules for discriminating signal propagation mode between a mobile station (MS)and receiving station (BS): if LOS mode is identified the system will use TOA method for ranging;if NLOS mode is identified the system will use RSSI method for ranging.Centroid method is widely used in the estimation of MS location in positioning part. This thesispresents the improved weighted centroid algorithm. According to the ranging part, this thesis usesthe improved weighted centroid method to estimate the location of the MS. Meanwhile according tothe role of each of the BS in the positioning process, system would set different weighting factor fordifferent BS.Simulation results show that the RSSI and TOA-based UWB hybrid positioning of the proposedalgorithm can reduce ambient noise and indoor multipath propagation effects on indoor positioningaccuracy. Simulation results show that the proposed positioning algorithm achieved betterpositioning performance. |
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