Types of small scale fading, based on Doppler spread area.Fast fadingb.Frequency selective fadingc.Flat fadingd.Frequency non selective fading

Small scale fading can be categorized based on the Doppler spread and delay spread. Here are the types:

1. Fast Fading: This type of fading occurs when the coherence time of the channel is smaller than the delay constraint of the channel. It is caused by rapid changes in the phase and amplitude of the signal caused by changes in the multipath environment.

2. Frequency Selective Fading: This type of fading occurs when the bandwidth of the signal is greater than the coherence bandwidth of the channel. Different frequency components of the signal experience different amounts of fading.

3. Flat Fading: This type of fading occurs when the bandwidth of the signal is less than the coherence bandwidth of the channel. All frequency components of the signal experience the same amount of fading.

4. Frequency Non-Selective Fading: This type of fading occurs when the bandwidth of the signal is smaller than the coherence bandwidth of the channel. In this case, all frequency components of the signal experience similar fading.

These types of fading are based on the Doppler spread (which is related to the movement of the user) and the delay spread (which is related to the multipath environment).