Estimating 28 GHz LMDS channel dispersion in urban areas using a ray-tracing propagation model

Broadband wireless systems such as LMDS operating in the millimeter wave band offer the potential for a highly flexible, high-speed, two-way information distribution network to serve local and metropolitan areas. To date, relatively little research has been done to characterize such wireless channels in order to determine the degree of sophistication required in the transmission hardware. This paper uses a ray-tracing propagation model to investigate the dispersive nature of the transmission channel in a typical urban environment. The results of this work show that highly directional antennas can effectively reduce channel dispersion so that high-speed digital transmission should be possible without requiring equalizers in the receivers. This research also suggests that intelligent use of stable reflection paths could provide an effective means of providing LMDS service to non line-of-sight locations.