HEXAGONAL CONSTELLATIONS AND DECODING SAME IN DIGITAL COMMUNICATION SYSTEMS

摘要

Embodiments of the invention provide a method of decoding of hexagonal constellations. The decoding methods exploit the inherent structure of the hexagonal grid to eliminate/minimize the requirements for distance computations. A constellation which has unused constellation points is received. A plurality of lookup tables is used for indicating whether a particular constellation point is used. The lookup tables are indexed using the two integers u and v. An initial estimate ū and v is found. The euclidean distance to the immediate neighbors resulting in the immediate upper and lower integers for ū and v is computed. From the distance to the nearest neighbor, the log-likelihood ratio value is computed.

主权项

1. A method of processing communications signals, comprising:
receiving, at a receiver, a constellation which has unused constellation points; using a plurality of lookup tables for indicating whether a particular constellation point is used and the corresponding codeword for the used constellation points; indexing the lookup tables using the two integers u and v; finding the initial estimate of u and v: ū and v; computing a modified Euclidean distance to the immediate constellation point neighbors that correspond to the upper and lower integers of ū and v; and from the distance to the nearest neighbor, computing the log-likelihood ratio value.