A comparison of RMS delay spread and coherence bandwidth for characterisation of wideband channels

This paper analyses the suitability of RMS delay spread and coherence bandwidth when characterising system quality-of-service of QPSK operating in a variety of wideband mobile channels. The most common technique for characterising the wideband channel is to calculate the RMS delay spread. Analytical development and simulation studies indicate that the presence of relatively low power signals with large excess delay has a much greater effect on the RMS delay spread than is reflected by a negligible change in system performance. Simulation models and analysis indicate that coherence bandwidth is not unduly influenced by the presence of negligible rays at a large excess delay. For the channel models under test, employing coherence bandwidth as a performance prediction parameter is more successful than the use of RMS delay spread.