Abstract: Disclosed is a method and apparatus for composing a received symbol signal modulated with a bit reflected Gray code into bit information. According to an embodiment of the present invention, a positive integer of the received symbol signal having bits is assigned according to the Gray mapping rule, and a sign is determined. A value that is indicative of an arrangement of the bits constituting the received symbol signal is calculated. A boundary value in at least one bit group consisting of the bits constituting the received symbol signal is acquired, and a difference from an absolute value of the received symbol signal is calculated. The received symbol signal is converted into information per bit using a value of the received symbol signal based on the positive integer and the determined sign, the value that is indicative of the bit arrangement, and the difference from the absolute value.

Abstract: Provided are an apparatus and method for generating a soft bit metric and a multi-level (M-ary) Quadrature Amplitude Modulation (QAM) receiving system using the same. The apparatus includes an analog to digital converter for converting an analog symbol signal of a demodulated I (Inphase) or Q (Quadrature) channel into a digital signal, a scaler for scaling the converted digital signal based on a reference value used for determining a space between symbols, a positive integer converter for calculating a positive integer of the scaled digital I or Q channel symbol signal, a sign determinator for determining a sign of the scaled digital I or Q channel symbol signal, and a bit information converter for converting the scaled digital I or Q channel symbol signal into soft bit metric information per bit on the basis of the calculated positive integer and the determined sign value.

Abstract: Disclosed is a method and apparatus for composing a received symbol signal modulated with a bit reflected Gray code into bit information. According to an embodiment of the present invention, a positive integer of the received symbol signal having bits is assigned according to the Gray mapping rule, and a sign is determined. A value that is indicative of an arrangement of the bits constituting the received symbol signal is calculated. A boundary value in at least one bit group consisting of the bits constituting the received symbol signal is acquired, and a difference from an absolute value of the received symbol signal is calculated. The received symbol signal is converted into information per bit using a value of the received symbol signal based on the positive integer and the determined sign, the value that is indicative of the bit arrangement, and the difference from the absolute value.

Abstract: Provided are an apparatus and method for generating a soft bit metric and a multi-level (M-ary) Quadrature Amplitude Modulation (QAM) receiving system using the same. The apparatus includes an analog to digital converter for converting an analog symbol signal of a demodulated I (Inphase) or Q (Quadrature) channel into a digital signal, a sealer for scaling the converted digital signal based on a reference value used for determining a space between symbols, a positive integer converter for calculating a positive integer of the scaled digital I or Q channel symbol signal, a sign determinator for determining a sign of the scaled digital I or Q channel symbol signal, and a bit information converter for converting the scaled digital I or Q channel symbol signal into soft bit metric information per bit on the basis of the calculated positive integer and the determined sign value.

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 continuous phase quadrature amplitude modulation and demodulation to continuously process phases and amplitudes at symbol change points in an M-ary quadrature amplitude modulation method.

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.