Measuring, modeling, and characterizing of indoor radio channel at 5.8 GHz

Wide-band indoor radio channel characterization for broadband radio access networks and unlicensed national information infrastructure has been performed at 5.8 GHz, and results are given in this paper. Delay spreads of 8.8 and 17.2 ns and coherence bandwidths of 9.6 and 4 MHz have been found for line-of-sight (LoS) and obstructed line-of-sight (OLoS) situations, respectively. Results have been compared with predictions made using a ray-tracing tool. To get accurate predictions, a good description of the electromagnetic properties of the obstacles present in the environment is needed. Several experiments were made in order to characterize the electromagnetic parameters of six typical building materials. Transmission and reflection coefficients were measured using the free-space technique. A multiple successive internal reflection model was used to estimate the permittivity and conductivity by comparing the measured and predicted values of the coefficients. Several samples of each material were measured, and the results vary from sample to sample. This variation has been characterized by the calculation of confidence bands for the parameters. The influence of both the dielectric parameters and the order of reflections considered in the ray-tracing tool has been analyzed. The effect is reduced on narrow-band predictions but is more important on wide-band parameters as the delay spread. It is shown that the measured delay spread cumulative distribution function falls within the band predicted using the measured maximum and minimum values of permittivity.