Abstract: An apparatus and method for estimation of channel state information in OFDM receivers. According to the invention, a noise power estimator is provided to evaluate an average noise power estimate on a sub-carrier of an OFDM symbol. Furthermore, a channel power calculator is provided to calculate a channel power on the sub-carrier from a channel response estimate. By calculating a ratio of the channel power to the average noise power estimate of the sub-carrier, a CNR calculator can estimate a carrier-to-noise ratio on the sub-carrier. Based on the carrier-to-noise ratio of the sub-carrier and a predetermined threshold, a CSI generator thus determines a CSI estimate for the sub-carrier. If the carrier-to-noise ratio of the sub-carrier is less than the predetermined threshold, the CSI estimate for the sub-carrier is set to the carrier-to-noise ratio of the sub-carrier divided by the predetermined threshold; otherwise, it is set to one.

Abstract: A method of mode detection for OFDM signals. The method comprises the steps of delaying the OFDM signal for a first and second number of samples, multiplying the two delayed signals by coefficient signals, and deriving a sum of the two products, deriving an error signal by subtracting the sum of the two products from the OFDM signal, extracting amplitudes of the coefficient signals, and accordingly deriving step size signals, updating the coefficient signals according to the error signal and step size signals, detecting edges of the amplitudes of the coefficient signals, and determining the guard interval length and transmission mode according to the detected edges.

Abstract: An equalization method and device for equalizing the received vestigial sideband (VSB) signal, utilizes segment-sync symbols, Sato directions, erasure slicers, and variable step-sizes. In addition to stop-and-go (SAG) mode, the directions of Sato errors can also be used for speed up the convergence of tap weights of the equalizer. Erasure slicers can mitigate the effect of decision errors as they are passed through the feedback filter. In time-variant environments, variable step-sizes help the equalizer tracking the variations of the channels; in time-invariant environments, variable step-sizes help ease the fluctuations of the steady-state equalizer tap weights, and therefore yield smaller mean-squared-error and better symbol error rate (SER).