Table of Contents
International Journal of Navigation and Observation
Volume 2015, Article ID 983124, 16 pages
Research Article

A Ray-Tracing Technique to Characterize GPS Multipath in the Frequency Domain

1Position, Location and Navigation (PLAN) Group, University of Calgary, Calgary, AB, Canada T2N 1N4
2European Commission, Joint Research Center, 21027 Ispra, Italy

Received 22 May 2015; Revised 24 August 2015; Accepted 6 September 2015

Academic Editor: David Akopian

Copyright © 2015 Naveen S. Gowdayyanadoddi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Multipath propagation is one of the major sources of error in GPS measurements. In this research, a ray-tracing technique is proposed to study the frequency domain characteristics of multipath propagation. The Doppler frequency difference, also known as multipath phase rate and fading frequency, between direct (line-of-sight, LOS) and reflected (non-line-of-sight, NLOS) signals is studied as a function of satellite elevation and azimuth, as well as distance between the reflector and the static receiver. The accuracy of the method is verified with measured Doppler differences from real data collected in a downtown environment. The use of ray-tracing derived predicted Doppler differences in a receiver, as a means of alleviating the multipath induced errors in the measurement, is presented and discussed.