Intelligent urban positioning, shadow matching and non-line-of-sight signal detection

High sensitivity receivers and multiple satellite constellations have vastly improved GNSS signal availability in dense urban areas. However, accuracy remains a problem due to the blockage and reflection of many of the signals by buildings and other obstacles. Reliable metres-level positioning in dense urban areas is difficult to achieve cost-effectively using a single technology. The way forward is to combine multiple positioning techniques. Intelligent urban positioning (IUP) aims to achieve this level of performance by combining positioning algorithms augmented with three-dimensional mapping; techniques for distinguishing between NLOS and LOS signals; and multi-constellation GNSS, using signals from all visible satellites. This paper reviews non-line-of-sight (NLOS) signal detection and presents results of a new C/N₀-weighted consistency checking method. It describes and presents results of shadow matching, a new method using a 3D city model to improve cross-street GNSS positioning accuracy. Finally, a method for combining the different components of IUP is presented together with the results of a preliminary demonstration of the IUP concept using GPS and GLONASS data collected in London.