Experimental Analysis of Multipath Effects on GNSS Positioning in Urban Canyon

Global navigation satellite system (GNSS) can provide us with three-dimensional coordinates information of any place on the earth. However, the multipath effects always cause a decrease in GNSS positioning accuracy. In this paper, we analyze and model the root mean square (RMS) delay spread (DS) in multipath channels and the GNSS pseudo-range error (PRE) based on channel measurements in an urban canyon scenario at both 1.575 GHz and 1.207 GHz. By constructing the probability density function (PDF) of RMS DS, it is found that the PDF can be well fitted by a lognormal distribution. In addition, compared with the International Telecommunication Union (ITU) standard, the mean value and standard deviation of RMS DS in the urban canyon are much smaller than those in the traditional urban micro-cellular scenario. Then, by modeling PRE as a function of the transmitter-receiver (Tx-Rx) elevation angle and RMS DS separately, the effect of the Tx-Rx elevation angle on PRE and the dependence of PRE on RMS DS are studied. It is found that the PRE increases linearly with the increases of the cotangent value of Tx-Rx elevation angle, and the fluctuation of PRE at 1.207 GHz is much larger than that at 1.575 GHz. Besides, there is a linear dependence of PRE on RMS DS, that is when RMS DS increases by 1 ns, PRE increases by 0.50 meters at 1.207 GHz and 0.53 meters at 1.575 GHz. These results are helpful for the research on multipath effects in urban canyon scenarios and the improvement of positioning accuracy for the GNSS.