A study of CW spatial fading of the indoor radio propagation channel

Results of the analysis of 160 segments of 1.5 meter CW envelope fading data are reported. The data were obtained by complex addition of the multipath components of the channel's impulse responses. Measurements were performed at two dissimilar office buildings, using four antenna separations of 5, 10, 20, and 30 meters per building, and 20 locations (1.5 meters in extent) for each antenna separation. Statistical analysis of the data indicates that: (i) the CW fading characteristics depend on the local environment of the portable (low) antenna, and are very similar at both buildings and for all antenna separations; (ii) there is higher degree of fluctuations for non-line-of-sight topographies; (iii) the average dynamic range of fluctuations is around 25 dB for both buildings and all antenna separations; deep fades of 30 dB to 40 dB below mean values have been observed; (iv) the signal envelope becomes essentially uncorrelated after a separation of 10 cm; and (v) the level crossing rates are on average 4.2, 2.2, 0.8, and 0.4 per 150 cm for threshold levels of 5 dB, 10 dB, 15 dB, and 20 dB below the mean value, respectively. The percentages of data below the threshold (i.e., duration of fades) are on the average 2.6% and 1.8% for threshold levels of 5 dB and 10 dB below the mean value, respectively.