Statistical Analysis of Urban GPS Multipaths and Pseudo-Range Measurement Errors

In urban environments one of the causes of pseudo-range measurement error in Global Positioning System (GPS) is short-delay multipaths due to the scatterers around the receiver. Therefore knowledge of the temporal distribution of GPS multipaths based on a statistical scatterer distribution in an urban environment is essential to estimating the positioning performance and to developing an efficient multipath mitigation technique for urban GPS applications. The work presented here introduces a scatterer distribution model for the urban environment, derives analytical expressions of the consequent time-of-arrival (TOA) probability density function (pdf) with respect to satellite elevation angles, and analyzes the effect of short-delay multipaths on the pseudo-range measurement errors. The expressions derived provide insights into the statistical properties of GPS multipaths and pseudo-range measurement errors in GPS code phase measurement functions due to the short-delay multipaths.