Coherence bandwidth and coherence time in an OFDM system While studying an OFDM system, I have encountered statements like coherence bandwidth is the reciprocal of delay spread and coherence time is the reciprocal of the Doppler spectrum.

Can somebody help me to understand this mathematically?

How is coherence bandwidth related to delay spread, and how is coherence time related to Doppler spread?
This diagram (from Molisch) shows the various Fourier relationships between measurements in wireless systems.