Measuring GNSS Multipath Distributions in Urban Canyon Environments

In general, standalone global navigation satellite systems (GNSS) receiver architectures cannot provide a position accuracy suitable for use in vehicular applications in urban canyon scenarios. Specifically, GNSS signals are affected by the surrounding objects, such as high buildings, trees, and so on, which introduces multipath errors. Multipath arises from the reception of reflected or diffracted signals, possibly in addition to the line-of-sight signal, and is one of the most detrimental error sources in GNSS positioning applications. Multipath distributions in the urban canyon area are measured and characterized in this paper. In particular, the Doppler and code phase delay under different conditions are assessed as a function of vehicle speed and signal power, which are different from previous calibration metrics. Specifically, multipath directional-dependence phenomenon (i.e., the variation resulting from the direction of travel of the user) is observed during this process, and the multipath maximum Doppler offset and minimum Doppler offset are derived and verified by the real data. The multipath distribution will eventually affect the search strategy (i.e., search space size, coherent integration time) utilized in the high sensitivity receiver.