[MPKZ01]. They de- during daytime on rare occasions it was higher than -10 termined the coherence time at 1.7 GHz, bandwidth dB, Figure 4.7-44. The authors recommend to use p as an 30 MHz, in Duisburg, with BS positions above rooftop indicator for non-static measurement situations in for and the Tstationary in the street, but with path lengths instance MIMO measurements [MeBH04]. Two differ- ranging from 20 to 320 m. Coherence was taken to be ent causes of channel dynamics were identified, distur- lost for correlation coefficients under 0.9, between fre- bances with low Doppler shifts and those with high quency spectra of snapshots averaged over all available Doppler shifts, with the first most likely related to people measurement-point pairs with the same time offset. The standing or sitting close to the antennas, at either side, and authors found median coherence period lengths between the second by people walking by. Medbo, Berg, and 4.3 and 6 S, depending on the location. Harrysson modelled the variations as the effect of moving persons, consisting of a cylindric scattering and a shad- owing component simplified as knife-edge diffraction. Characterisation of special outdoor Qualitatively good correspondence between measure- environments ments and model was reported [MeBH04]. Richly scattering environments in an industrial setting Skentos et al. examined static rooftop-to-street were investigated by Kemp and Bryant, with Bluetooth scenarios for a wide, busy avenue in Athens under LoS applications in the 2.4 GHz Industrial, Scientific and propagation conditions [SKPC04]. The receiver was Medical (ISM) band in mind [KeBr05]. Path lengths placed on top of a building at 10 height, the transmitter were therefore relatively short, about 20 m on a petro- at four positions at street level, 1.9 m above ground, be- chemical plant, 80 m on a car park lined with multistorey tween 115 to 236 m away from the transmitter. The buildings, and up to 250 m on an electricity distribution carrier frequency was 5.2 GHz, the bandwid