Patent ID: 7684522

Claim:
A method of a receiver determining a Log-Likelihood Ratio (LLR) corresponding to each bit of a symbol, the symbol comprising a predefined number of bits based on a predetermined constellation, the method comprising: a. the receiver expanding the predetermined constellation, the predetermined constellation comprising a plurality of constellation-points, each constellation-point having a unique X co-ordinate and Y co-ordinate, wherein the expanded predetermined constellation further comprises points corresponding to each combination of the X co-ordinate and the Y co-ordinate of the constellation-points; and b. the receiver calculating the LLR corresponding to each bit of the symbol based on the expanded predetermined constellation; wherein the X co-ordinate and the Y co-ordinate of a pair of constellation-points are interleaved, wherein interleaving the X co-ordinate and the Y co-ordinate of the pair of constellation-points comprises forming a new interleaved first symbol, x 0 , from a real component of a first complex symbol, s 0 , and an imaginary component of a second complex symbol, s 1 , and forming a new interleaved second symbol, x 1 , from a real component of the second complex symbol, s 1 , and an imaginary component of the first complex symbol, s 0 ; wherein the predetermined constellation is a pre-coded Quadrature Amplitude Modulation (QAM) constellation, wherein the constellation-points on the constellation of the pre-coded QAM constellation satisfy at least one predefined condition; and wherein the at least one predefined condition comprises the X co-ordinate of a symbol point selected from a first set and the Y co-ordinate of the symbol point selected from a second set wherein the second set is a complement of the first set.