Patent ID: 7313750

Claim:
A receiver system for receiving signals comprising: a demapper device being responsive to an equalizer output for processing the equalizer output to generate a demapper output, said demapper output for including one or more bit metrics, said receiver system being responsive to a received signal for processing the received signal to generate said equalizer output, said demapper device for using a distance measure to calculate said bit metrics, said receiver system for using said demapper output to generate a processed output; and a convolutional decoder being responsive to said processed output for processing the processed output to generate a decoded bit sequence, said convolutional decoder for using said processed output to generate one or more path metrics, said convolutional decoder for using said bit metrics and said path metrics to generate said decoded bit sequence, said receiver system for using said distance measure to reduce the size of said bit metrics and the size of said path metrics to improve the performance of said convolutional decoder; wherein said received signal being modulated using a modulation scheme, said received signal for including a bit sequence comprising an in-phase bit b I,k and a quadrature bit b Q,k , said modulation scheme for including a constellation for being partitioned into two sets of in-phase symbols S I,k (0) and S I,k (1) , said constellation for being partitioned into two sets of quadrature symbols S Q,k (0) and S Q,k (1) ; and wherein said distance measure is a simplified Manhattan distance having an in-phase part d I,k c and a quadrature part d Q,k c , said equalizer output for including an i th subcarrier, each of said bit metrics for including an in-phase bit metric m(b I,k ) c and a quadrature bit metric m(b Q,k ) c , said demapper device for using a channel frequency response H(i) for said i th subcarrier and a minimum function (min) to calculate said in-phase bit metric according to m ⁡ ( b I , k ) c =  H ⁡ ( i )  2 · min α ∈ S I , k ( c ) ⁢  y I ⁡ [ i ] - α I  =  H ⁡ ( i )  2 · d I , k c , c = 0 , 1.