A coded frequency-domain link adaptation scheme for OFDM transmission in TDD mode

The link adaptation scheme in the current orthogonal frequency division multiplexing (OFDM) systems such as IEEE802.11a only consider the channel variation in the time-domain, and assume all the data subcarriers use the same modulation mode and transmit power once the data rate is determined. However, in the frequency-selective fading environments, the error probability performance of OFDM is severely degraded by the subcarriers where the deep fading occurs. In order to deal with this issue, we propose a coded frequency-domain link adaptation scheme for OFDM packet transmission in the time division duplex (TDD) mode. This scheme is based on the concatenation of the channel coding and the adaptive bit and power loading. The simulation results show the proposed scheme can significantly improve the packet error rate (PER) performance compared with other schemes. Further investigations also show that it can contribute to large performance gain even in the challenging high-speed environments.