Patent ID: 9059881
Filing Date: 2015-06-16
Classification: H04L

Abstract:
1. A method of processing communications signals, comprising: receiving, at a receiver, a constellation which has a plurality of unused constellation points; using a plurality of lookup tables for indicating whether a particular constellation point is used and a corresponding codeword for the used constellation point; indexing the lookup tables using an integer u and an integer v; computing an initial estimate of the integer u and the integer v giving an integer ū and an integer a normalized received symbol is where (x,y) are the coordinates of the received symbol r and where (x0,y0) is a fixed perturbation for symbol r0 that could be used to minimize the maximum energy Eg; computing a modified Euclidean distance to an immediate constellation point neighbor that corresponds to the upper and lower integer of ū and ū; and from the distance to the immediate constellation point neighbor, computing a log-likelihood ratio value.