Measurements and analysis of the indoor wideband millimeter wave wireless radio channel and frequency diversity characterization

The paper presents results of frequency domain measurements conducted to evaluate the effectiveness of frequency diversity in mitigating the effects of multipath fading in indoor microcellular channels employing an omnidirectional receive antenna in the band 63.4-65.4 GHz. The performance of frequency diversity for 155 MHz and other channel bandwidths to accommodate modulated signals with data rates up to 155 Mb/s is presented. Results are obtained using maximum selection combining and presented as functions of frequency separation between the diversity branch signals. Improvements in the level crossing rate and average fade duration are given together with improvement in the k-Rician factor. The root mean square (rms) delay spread (τ_rms) and coherence bandwidth (β_c) of the channel are also presented as functions of distance between terminals. Values of β_c for correlation levels of 0.9, 0.7, and 0.5 are given together with the cumulative distribution functions of τ_rms. The levels below which the coherence bandwidth stays for 90% of receiver positions are estimated. Measurements were repeated under identical test conditions but with the receive omnidirectional antenna replaced by a directional horn in order to characterize the effect of the receive antenna radiation pattern on the indoor radio channel characteristics.