Patent ID: 7680214

Claim:
A method on a communication receiver having a soft bit generator and a turbo decoder, the method for computing a threshold Sth i used in demodulating a quadrature amplitude modulated (QAM) signal received by the communication receiver to generate a plurality of soft bits per received symbol for input to the turbo decoder, the method including the steps of: the soft bit generator: computing a mean amplitude A of the received symbols; multiplying the mean amplitude A by a constant C i for a square QAM constellation with 4 m points, such that Sth i =A×C i where m is a positive integer and I is a positive integer from 1 to (√{square root over (4 m-1 )})−1; computing one or more of the soft bits from the threshold Sth i ; and outputting the computed soft bits to the turbo decoder.