What is frequency-selective fading channel?

A frequency-selective fading channel is a type of wireless communication channel where different frequency components of a signal experience varying levels of attenuation and delay due to multipath propagation. This results in some frequencies being more affected by fading than others, leading to distortion of the transmitted signal. Such channels can cause inter-symbol interference (ISI), making it challenging for the receiver to accurately decode the transmitted information. Techniques like equalization and diversity are often employed to mitigate the effects of frequency-selective fading.