Doppler compensation for chunk-based OFDMA systems

Doppler distortions caused by mobile users destroy the orthogonality of the signals used in OFDMA systems, causing severe interferences which may limit the system performance. We propose a scheme to estimate and compensate the Doppler distortions in OFDMA systems, where users are assigned subbands of contiguous subcarriers, so called chunks. The scheme is based on exclusively designed pilot symbols used to estimate the channel and Doppler distortions and relies on frequency and time domain interpolation techniques. Application of the scheme is shown to yield significant improvements of the signal to interference conditions.