The impact of imperfect one bit per subcarrier channel state information feedback on adaptive OFDM wireless communication systems

Abstract

If the channel state information (CSI) is available at the transmitter, adaptive techniques can be applied to mitigate deep fading in OFDM wireless communications. The performance of adaptive OFDM systems with average one bit per subcarrier CSI feedback transmitted through perfect feedback channel has been studied in (Y. Rong et al, Globecom, 2004). However, in practical situations, the assumption of a perfect feedback channel may be unrealistic. In this paper, we study the impact of an imperfect feedback channel on the performance of adaptive power allocation (APA) and adaptive modulation selection (AMS) techniques considered in the previously mentioned paper. We determine that the one bit feedback-based APA technique is relatively robust to erroneous feedback as compared to the one bit feedback-based AMS approach, while the latter is relatively robust against feedback delays as compared to the former. It is also shown that by exploiting the knowledge of the feedback channel the performance of these two adaptive techniques can be improved.