Multipath scattering model for LMDS

A model for multipath interference that more accurately depicts scattering mechanisms at frequencies allotted for local multipoint distribution service (LMDS) is proposed. The LMDS system addressed in this paper uses orthogonal frequency division multiplexing (OFDM). The proposed model is not statistical as is normally the case in most LMDS studies but relies on the geometrical theory of diffraction (G´I´D) that uses ray tracing techniques to model multipath scattering behavior in the low-to-mid GHz frequency range. Our study shows that the GTD multipath scattering model provides significant insight into the performance of LMDS systems operating in the GHz range. It is shown that OFDM performance may degrade significantly depending on the number and geometric features of the sources of multipath scattering. This work provides some insight into where it is appropriate to house or locate LMDS systems.