ABSTRACT
The effectiveness of adaptive modulation depends on the number and possible values of the parameters to be tuned. The time-frequency structure of orthogonal frequency division multiple access (OFDMA) signals lends itself very well to adaptation because modulation, coding, and power for each user may not only be changed at the orthogonal frequency division multiplexing (OFDM) symbol level but also at the subcarrier level, that is, independently for each subcarrier or group of subcarriers, provided that proper channel information is made available [3].
