# Frequency-selective channel: Basic in theory

In a lecture, it was covered a topic "frequency selective and flat fading channel models".

For case, the frequency selective channel we have a channel impulse response H for each frequency, is varying in frequency.

Last week I have a lab task where I have implemented the different precoding algorithms. Now I am thinking about how you calculate a precoding matrix for the frequency selective channel. You have more than one channel response, so you have to calculate for each of them. A calculation takes long. Of course, Matlab can do that very fast but you can have more than thousands response and it takes a long for Matlab too. How do you calculate in that case a precoding matrix? Do you take an average?

Best regards

Noel