RMS Delay Spread in Indoor LOS environments at 5.2 GHz

Measurements and modelling of rms delay spread (RDS) in indoor line-of-sight (LOS) conditions at HIPERLAN/U-NII frequencies (5.2GHz) with omni-directional antennas show that the maximum RDS in a room is dependent on the dimensions of the room and the reflection coefficient of the walls. Furthermore, in a given room RDS increases with distance from the transmitter up to a maximum value and plateaus at this maximum over a large part of the room. Introduction: Intersymbol interference brought about by propagation through a dispersive channel is a major problem in the design of high-speed wireless networks. The rms delay spread (RDS) [1] is a commonly used practical measure of the extent of time dispersion introduced by multipath channels. In turn, it has been found [2] that RDS is directly related to the minimum symbol length that can be used in order to avoid excessive intersymbol interference. The objective of this research was to investigate RDS and its relationship to the dimensions and material properties of the indoor LOS environment. A model for RDS in a bounded room was derived and this was tested against measurements conducted at 5.2 GHz in various residential properties and business premises. The results from modelling and measurements are in good agreement. Several new and important conclusions are presented from this study.