In layman terms, why doppler spectral power density has U shape?
Does this mean that frequency components with maximum doppler shift have maximum power?
I am confused with the interpretation of the doppler spectral power density U-shaped graph, for example the one at https://blog.taitradio.com/2015/09/23/9-channel-concepts-every-system-designer-needs-to-understand/.
Additionally, I found this source: https://www.sharetechnote.com/html/Handbook_LTE_Fading.html. Does this mean that the U-shaped graph actually depicts probability density of frequency shifts and has nothing to do with the power/amplitude?