A method for differentially coherent detection of OFDM signals on Doppler-distorted channels

Doppler distortion causes inter-carrier interference which prevents the use of differentially coherent detection in OFDM systems. To recover this efficient detection method, we propose to use several FFT demodulators operating in parallel over non-overlapping time segments, and to combine their outputs prior to detection. This technique aims for efficient implementation of front-end matched filtering, followed by differential MMSE combining. A low complexity algorithm is proposed for recursive computation of combiner weights, and its gain over the conventional detector is quantified through numerical examples of an underwater acoustic channel with severe Doppler distortion.