Information is transmitted over selected, Orthogonal Frequency Division
Multiplexed (OFDM) sub-channels to avoid frequencies with unacceptable
congestion, noise or interference levels. Using frequency hopping,
selected non-contiguous OFDM sub-channels used for transmission may vary
with time. Once a group of OFDM sub-channels is selected, a power level
and modulation technique may also be selected based on channel quality.