1. A method of performing coherent detection for differentially encoded orthogonal-frequency-division-multiplexing (OFDM) systems, said method comprising: providing a series of consecutive OFDM data symbols in a digital multimedia broadcasting (DMB) frame of a signal transmitted to a wireless receiver; storing a channel phase value of a first OFDM data symbol in said series of consecutive OFDM data symbols; calculating a primary estimate of said channel phase difference by hard thresholding said first OFDM data symbol; combining said channel phase value of said first OFDM data symbol with said primary estimate of said channel phase difference; generating a secondary estimate of a said channel phase difference of a second OFDM data symbol based on the combined channel phase value of said first OFDM data symbol and said primary estimate of said channel phase difference, wherein the first and second OFDM data symbols are consecutive OFDM data symbols in said DMB frame; correcting decisions of which OFDM data symbols to encode based on said secondary estimate of said channel phase difference; and sending the corrected decisions to a Viterbi decoder in said wireless receiver for decoding of said OFDM data symbols.