| 摘要 |
<p>Disclosed is a 16-ary QAM (Quadrature Amplitude Modulation) demodulation apparatus for receiving an input signal R k (X k , Y k ) comprised of a k th quadrature-phase component Y k and a k th in-phase component X k , and generating soft values ›(s k,0 ), ›(s k,1 ), ›(s k,2 ) and ›(s k,3 ) for the input signal R k (X k , Y k ) by a soft decision means. A first calculator decides a soft value ›(s k,2 ) of a third demodulated symbol among 4 demodulated symbols by subtracting a distance 2a between two demodulated symbols on the same axis of a mapping table from a level |Y k | of the quadrature-phase component Y k . A second calculator decides a soft value ›(s k,3 ) of a fourth demodulated symbol by calculating Y k +±*Z k using a first variable ± determined by the soft value of the third demodulated symbol and a sign bit of the quadrature-phase component Y k . A third calculator decides a soft value ›(s k,0 ) of a first demodulated symbol by subtracting the distance 2a from a level |X k | of the in-phase component X k . A fourth calculator decides a soft value ›(s k,1 ) of a second demodulated symbol by calculating X k +²*Z' k using a second variable ² determined by the soft value of the first demodulated symbol and a sign bit of the in-phase component X k .</p> |
