Channel characterization for indoor wireless communications at 21.6 GHz and 37.2 GHz

This paper presents results of narrowband and wideband measurements of the indoor wireless channel at 21.6 GHz and 37.2 GHz. Narrowband measurements with antenna diversity were carried out using a modified Spectrum Analyzer operating as a two channel receiver. With this arrangement, two different environments were considered and in each between 10 and 20 measurements were taken. Average cumulative distribution functions are computed and distance-power law exponents are estimated. Wideband characterization involved a Vector Network Analyzer which collects frequency-domain measurements of the channel transfer function H(f) at 21.5 GHz. The duration of each of these measurements was 100 msec during which there was no motion or movement of people in the environment. This ensures that the channel remains static. The impulse response of the channel is then calculated using Inverse Fourier Transformation. From the above measurements, average and worst case statistics can be derived and used to evaluate radio coverage for various systems configurations. Such configurations include line-of-sight and obstructed measurements within environments such as rooms and hallways. Values for the delay spread are also calculated which will permit evaluation of maximum transmitted symbol rates for intersymbol interference-free indoor radio communication.