Multipath propagation and LOS interference studies for LMDS architecture

Broadband radio access systems operating at millimeter waves, used for the local multipoint distribution service (LMDS), have a large bandwidth of up to 2 GHz but a very limited coverage to a few kilometers only. This is mainly because they require clear line of sight (LOS) between the base station and the subscriber antennas as well as because millimeter waves suffer from large propagation losses, particularly free-space propagation losses and attenuation caused by rain. However, in urban areas, the LOS requirements and the capacity needed for interactive services are more likely to limit the maximum cell size than the basic radio propagation characteristics. To enhance coverage to customers where LOS is not possible, passive and active repeaters may be used. In this paper we present results of reflection measurements, multipath studies and LOS interference calculations for LMDS.