High Data Rate OFDM System with Simplified DAPSK Demodulation

In this paper, a simplified differential amplitude demodulation scheme for high-level Differential Amplitude and Phase Shift Keying (DAPSK) techniqus is proposed, which requires fewer thresholds for demodulation and thus has lower complexity. The performance of the Orthogonal Frequency Division Multiplexing (OFDM) system combined with the simplified DAPSK scheme is investigated over frequency-selective fading channels, then. Compared with coherent QAM-OFDM system, DAPSK-OFDM system has much lower complexity since channel estimation and equalization are unnecessary. Further more, under the condition of the same data rate, DAPSK-OFDM can achieve the performance close to or even better than that of QAM-OFDM system which adopts pilot symbols for channel estimation, by employing the concatenated code and utilizing the additional redundancy for outer coding at high Signal-to-Noise Ratios (SNRs).