SOME INVESTIGATIONS ON AN INDOOR RADIO CHANNEL AT 900MHs

Abstract

In recent years, indoor radio propagation has been studied extensively due to its applications in wireless local area networks (WLAN) and personal communication services (PCS). These studies can be performed either in time domain or in frequency domain. Wideband and narrowband measurements were been performed in frequency domain for the characterization of an indoor radio channel in the triple-storied building of Department of Electronics and Computer at IIT, Roorkee. From the wideband measurements, channel impulse response has been obtained by taking inverse Fourier transformof the channel_ frequency response. Power delay profile, RMS delay spread and Coherence bandwidth have been - obtained for this channel. Narrow band measurements have been performed in different environments and pathloss law has been obtained for each case. The propagation E_ .environments considered include line of sight (LOS) as well as obstructed line of sight (OLOS) cases.) Since it is not always feasible to make measurements for all possible propagation scenarios, a theoretical model becomes necessary. For the propagation environment considered for the measurement, a theoretical model has been developed using the ray tracing technique. The model takes into account the direct rays, the reflected rays, the transmitted rays, and the diffracted rays. Thcçis ~— computationally efficient in that it considers only the rays which can possibly iii reach the receiver. Simulation results have been compared with the measurement results to check the validity of the model. It is found that the results of simulation closely match with the results obtained from measurement, thus establishing the usefulness of the theoretical model as an efficient tool for prediction of the propagation characterization.