Adaptive multicarrier modulation for wireless systems

We propose an adaptive multicarrier modulation technique, where transmit rate and power are adapted in both time and frequency. We derive the optimal adaptation strategy and determine its performance. We also compare this performance with that of multicarrier systems that adapt only in the temporal or spectral domains. Our results indicate that as long as these domains have enough degrees of freedom, adaptive modulation across one domain performs almost the same as the more complex two dimensional adaptive policy. If, however, rate or power is restricted to be constant over the time and/or frequency domains, two dimensional adaption policy shows significantly better performances than adaptive modulation across one domain.