Patent ID: 8503552

Claim:
A method for receiving digital data using QAM symbols, each received symbol (y) corresponding to a number Q of bits determined by an order of QAM modulation used and the QAM symbols being defined in a constellation C x , the method comprising the steps of: estimating from the received digital data a noise power (N 0 ) and a channel coefficient (h), de-mapping the received symbol (y) to provide soft-information for decoding the received digital data, the de-mapping comprising: pre-equalizing the received symbol (y) by the channel coefficient (h) for obtaining a pre-equalized signal (z) determined by a real part (z′) and an imaginary part (z″); calculating a distance from the pre-equalized signal (z) to a certain point of the constellation C x using the real part (z′) and the imaginary part (z″) of the pre-equalized signal (z), the calculating the distance including calculating a real coordinate of the distance (d′) and an imaginary coordinate of the distance (d″) according to the expressions: d′=|2└z′/2┘+1−z′|, d″=|2└z″/2┘+1−z″|; calculating for at least one bit of the received symbol (y) an L-value (D q ) using the pre-equalized signal (z) and the calculated distance.