Electronics and Telecommunications Research Institute

Dong-Weon Yoon

Dae-Ig Chang

Deock-Gil Oh

Nae-Soo Kim

Sang-Kyu Park

Kwang-Min Hyun

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.

Apparatus and method for generating soft bit metric and M-ary QAM receiving system using the same

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.

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Seoul, South Korea

Dong-Weon Yoon