Underestimation of the RMS Delay Spread When using Uniform Tapped Delay Lines In Wireless Communications

Abstract

Tapped delay lines are widely used to model impulse responses of radio channels. This letter analytically proves that uniform tapped delay lines under-estimate the RMS delay spread (RMS-DS) corresponding to the channel being modeled by the line. However, the mean delay is exactly the same. Data from other publications is used in order to assess this result. Microcells measurements are used to build 3, 6 and 9 tap models so that both the mean and the variance of the relative error are calculated. In this way, it is observed the fact that the more taps are considered, the lower such error is.