Abstract: An apparatus and a method for demodulation using detection of channel adaptive modulation scheme are disclosed. The apparatus includes: a receiving unit for receiving a signal modulated based on the channel adaptive modulation scheme from an external; a demodulating unit for demodulating the modulated signal according to modulation scheme information; a modulation scheme detecting unit for determining modulation scheme information by detecting mapping information from the demodulated signal and outputting the modulation scheme information to the demodulating unit; and a decoding unit for performing an error correction on the demodulated signal and decoding the demodulated signal by using the determined modulation scheme information.

Abstract: Disclosed is a soft decision decoder, and a log likelihood ratio calculator for soft decision decoding and a method thereof, for realizing a generalized log likelihood ratio algorithm in consideration of channel estimation errors for performing soft decision decoding on QAM signals, which comprises multipliers for multiplying reference signals and channel estimation signals, subtractors for subtracting a receive signal of a receiver from output signals of the multipliers, first and second square calculators for squaring the subtractors' output signals and reference signals, dividers for dividing output signals of the first and second square calculators by addition values, and a comparator for comparing output signals of the dividers.

Abstract: An apparatus for resolution of phase ambiguity is disclosed. The apparatus receives modulated signal and resolves a phase ambiguity of the modulated signal while recovering the modulated signal to original data, wherein the apparatus includes a phase ambiguity detector for receiving demodulated data and frame synchronization information, and detecting a phase ambiguity value from the demodulated data based on a frame synchronization information; a phase ambiguity eliminator for receiving the phase ambiguity value and the demodulated data, and generating a phase ambiguity eliminated data by inverting the phase ambiguity value and multiplying the inverted phase ambiguity value and the demodulated data. The present invention can resolve a phase ambiguity occurred in various modulation modes including a burst mode communication with same algorithm so it can effectively implemented to an adaptive MODEM.