Fast/Slow Fading How are doppler shift and coherence time related?

1. What is the relation between coherence time and Doppler spread?
2. What way coherence time is related with maximum Doppler shift?
3. What are the causes of fast and slow fading distinguish between them?
4. How fading is affected by Doppler spread and multipath time delay spread?

What is the relation between coherence time and Doppler spread?

The coherence time T_c is fundamentally interpreted as the order-of-magnitude duration of a fade at a given frequency. The Doppler shift and Doppler spread are both linear functions of the signal frequency. The variation of Doppler spread with frequency is important when the operating frequency bands are different.

What way coherence time is related with maximum Doppler shift?

The Doppler spread and coherence time are inversely proportional to one another. That is, Coherence time is actually a statistical measure of the time duration over which the channel impulse response is essentially invariant, and quantifies the similarity of the channel response at different times.

What are the causes of fast and slow fading distinguish between them?

Fast fading and slow fading are considered as small-scale fading. Frequency dispersion due to Doppler spreading causes the transmitted signal to undergo either fast fading or slow fading, where the high Doppler spread gives rise to fast fading and the low Doppler spread brings about slow fading.

How fading is affected by Doppler spread and multipath time delay spread?

The channel Impulse response changes rapidly within the symbol duration. That is, the coherence time of the channel is smaller than the symbol period of the transmitted signal. This causes frequency dispersion, also called time-selective fading, due to Doppler spreading.