A frequency offset compensation scheme for the received signal under the influence of Rician fading channels with a direct component shifted by Doppler effect

A scheme that estimates and compensates for the frequency offset from the phase rotation of pilot symbols is proposed as a carrier frequency offset compensation scheme that periodically inserts pilot symbols in the transmitted signal. Since the frequency offset is estimated and compensated for at a frequency close to the direct path wave when a conventional scheme is applied in a Rician fading environment where the direct path wave is Doppler shifted, the Doppler spread appears to widen further, the estimation error of the fading distortion increases, and the error rate performance degrades. In this paper, we propose a frequency offset compensation scheme that estimates the center frequency of the Doppler spread and reduces the effects of the Doppler-shifted direct path wave by (1) calculating the signal power in the frequency domain by taking the discrete Fourier transform (DFT) of the pilot symbols and (2) smoothing the signal power in a frequency window. Computer simulations demonstrate the superior error rate performance of the proposed scheme compared to the conventional scheme and clearly show its effectiveness. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(12): 65–75, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10006