An interesting parameter deserving special attention is the carrier frequency. The frequencies
considered in these results were: 450 MHz, 850 MHz, 1.3 GHz, 1.7 GHz, 4 GHz, and 98
GHz, to name a few. For some measurements conducted, no significant statistical difference in
delay spread was found at these frequencies. What this indicates is that RMS may not, by itself,
limit the choice of a higher carrier frequency operating within a large building. We have chosen
to show an example where the measured delay spread statistics for a particular environment
showed relatively no difference for a few carrier frequencies chosen (specifically 850 MHz and
1.7 GHz). This is shown in Fig. 3.23 [22].
The above results correspond to an office building in New York City (NYC) that measured
approximately 61 m by 61 m in size.
However, there were also other published measurements that concluded RMS to decrease significantly
as the carrier frequency increased. Below we reproduce results supporting such statements in
Figs. 3.24 and 3.25 [23].
The above-measured propagation results were taken in a university in Canada. The legend used
above shows I 37.2 GHz and J 893 MHz. The higher carrier frequency had the smaller delay
spread statistics in the channel.
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