Adaptive frame selection algorithm for DVB-T

Orthogonal frequency division multiplexing (OFDM) systems transmit a guard-interval, inserted in front of the effective symbol period, using signals copied from some of the last parts of the effective symbol period. This guard-interval is used to reduce distortions due to multipath conditions. However, conventional OFDM systems produce inter-symbol interference (ISI) under severe multipath or pre-ghost channel conditions even though they accurately estimate the effective symbol period. Accordingly, the paper proposes a frame selection algorithm for a fast Fourier transform (FFT) operation in an OFDM receiver to remove the ISI produced in conventional OFDM systems under multipath conditions. The proposed algorithm replaces some of the rear parts of the effective symbol period with some of the guard-interval as an FFT input frame. The replaced period in the FFT input frame is changed according to the multipath environment. Four estimation methods for determining the replaced period are also described.