Frequency-time domain transmit power adaptation for OFDM systems in multiuser environment

The optimal transmit power adaptation method to maximise the channel capacity of an OFDM system in a multiuser environment is developed, and is found to be water-filling in the frequency-time domain over the best subcarriers among those of multiple users at each time. The results show that the frequency-time domain power adaptation yields greater capacity than the power adaptation in the frequency domain only.