Anchor selection by geometric dilution of precision for an indoor positioning system using ultra-wide band technology

In wireless localization systems, the performance enhancement of location estimation is an important goal. In recent years, different positioning systems using an ultra-wide band (UWB) technology have been created, and always an evaluation metric to test such systems is needed for ensuring a suitable system for a specified application. Also, a non-line-of-sight (NLOS) identification and mitigation method is needed usually when utilizing the UWB technology. The mean-square-error (MSE) and geometric dilution of precision (GDOP) evaluation metrics are widely implemented as standard for choosing a perfect system. In a harsh environment, a novel algorithm of indoor positioning (IP) system is presented using the UWB technology without implementing any NLOS identification and mitigation technique and the localization accuracy is evaluated online. The UWB is used to communicate a mobile station (M) with n anchor nodes distributed randomly and clustered by utilizing a combination method to create different groups, and then a conventional linearized least square (LLS) method is utilized by each group for locating M. A weighted GDOP metric is implemented online to assess the positioning accuracy of each group. Then, the group having the lowest positioning error among other groups is selected to relocate M using a proposed LLS, named modified LLS, for the selected group to enhance the positioning accuracy. The created system outperforms different IP systems in the market for the last decade in terms of time, complexity, and accuracy. The created IP system has a positioning error around 25 cm² of MSE in a hard environment, which is less than those of different IP systems created recently in the market.