1. An orthogonal frequency-division multiplexing (OFDM) system, comprising: a hardware processor configured to: quantify a frequency selectivity in a channel by calculating a difference in a magnitude of a channel and angle between adjacent sub-carriers of a plurality of sub-carriers in a frequency domain; determine the peaks (maxima) and the valleys (minima) in at least one of the channel magnitude and angle across a plurality of sub-carriers and count a number of zero-crossings; comparing the number of zero-crossings to at least one threshold to classify the channel; and a transmitter for transmitting an amount of information to a beamformer based on the channel classification.