Patent ID: 7583744

Claim:
A device for estimating log-likelihood ratio (LLR) decoder metrics from a soft decision having an in-phase component and a quadrature component, the soft decision having been demodulated in accordance with an eight-ary phase shift keyed (8PSK) modulation scheme, the device comprising: a first multiplier configured to multiply the in-phase component by a first constant value to generate a first LLR metric; a second multiplier configured to multiply the quadrature component by the first constant value to generate a second LLR metric; and a module configured to (1) subtract an absolute value of the quadrature component from an absolute value of the in-phase component to produce a difference value, (2) add the absolute value of the in-phase component to the absolute value of the quadrature component to produce a sum value, (3) divide a second constant value by a square root of a sum of a square of the in-phase component and a square of the quadrature component to produce a quotient value, and (4) multiply the difference value, the sum value, and the quotient value to generate a third LLR metric.