In this paper, we present an adaptive modulation technique for orthogonal frequency division multiplexing (OFDM) and enhance the performance of adaptive OFDM using a novel channel prediction. Adaptive modulation technique has been shown to achieve reliable high-rate data transmission over frequency-selective fading channel when OFDM is employed. This scheme requires the accurate channel information between two stations for a better performance. In an outdoor high mobility environment, most of adaptive OFDM systems have to be given the channel information transmitted from the receiver. Even if it is possible, there is some delay. Moreover, the channel impulse response between two stations is very rapidly varied. If the channel information is obsolete at the time of transmission, then poor system performance is the result. In order to solve this problem, we propose adaptive OFDM with channel predictor over frequency-selective and rapid fading channel for broadband wireless communications. Our proposal mitigates the effect of channel delay. Robust approach is less sensitive to outdated channel information. Performance results show that the proposed scheme can achieve considerable performance enhancement.
['Tae Jin Hwang', 'Ho Seon Hwang', 'Heung Ki Balik']
Adaptive OFDM with channel predictor over frequency-selective and rapid fading channel