This paper investigates the measurement uncertainty introduced by measurement instruments in frequency domain channel measurement systems. The uncertainty is a quantitative indication of the quality of the measurement results, so it provides a quantitative reference to chose appropriate instruments and measurement methods. The uncertainty analysis is based on Monte Carlo method. To account for the correlations between S-parameter measurements for different frequencies, covariance-matrix-based analysis is performed. The experiments in this paper show that the correlations have a strong influence on the uncertainties of channel parameter measurements. This paper illustrates the method for uncertainty analysis and provides the typical uncertainties of path loss and rms delay spread for the ultra wideband (UWB) channel measurements. For frequency domain channel measurement, the measurement instrument, Vector Network Analyzer (VNA), need to be calibrated. The different calibration methods lead to different measurement uncertainties. This paper presents the uncertainties for different calibration methods. Based on the uncertainty analysis, the response calibration method is suggested for channel measurements. It is the first time to provide the suggestion based on quantitative analysis.
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