Hexagonal constellations and decoding same in digital communication systems
AssigneeTexas Instruments Incorporated
InventorsMohamed Farouk Mansour, Lars Jorgensen
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Abstract
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.
Claims24
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.
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 wherein unused constellation points are flagged and wherein a plurality of entries of the tables are the codewords of the actual constellation points;
- computing the modified Euclidean distance to the immediate neighbors resulting in the immediate upper and lower integers for ū and v;
- selecting the upper or lower integer that corresponds to the smallest distance, if it is used in the constellation;
- and
A device comprising:
- a receiver;
- a processor, coupled to the receiver;
- a computer-readable medium including computer-readable instructions stored therein that, upon execution by the processor, perform operations comprising:
- receiving 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.
A device comprising:
- a receiver;
- a processor, coupled to the receiver;
- a computer-readable medium including computer-readable instructions stored therein that, upon execution by the processor, perform operations comprising:
- receiving a constellation which has unused constellation points;
- using a plurality of lookup tables for indicating whether a particular constellation point is used wherein unused constellation points are flagged and wherein a plurality of entries of the tables are the codewords of the actual constellation points;
- computing the Euclidean distance to the immediate neighbors resulting in the immediate upper and lower integers for ū and v;
- selecting the upper or lower integer that corresponds to the smallest distance, if it is used in the constellation;
- and
A computer program product of computer-readable instructions, tangibly embodied on a non-transitory computer-readable medium and executable by a digital data processor to perform actions directed toward transmitting a signal, the computer-readable instructions configured to cause a device to:
- receiving 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 the Euclidean distance to an immediate neighbors resulting in the immediate upper and lower integers for ū and v;
- selecting the upper or lower integer that corresponds to the smalling distance, if it is used in the constellation;
- and
A computer program product of computer-readable instructions, tangibly embodied on a non-transitory computer-readable medium and executable by a digital data processor to perform actions directed toward transmitting a signal, the computer-readable instructions configured to cause a device to:
- a receiver;
- a processor, coupled to the receiver;
- a computer-readable medium including computer-readable instructions stored therein that, upon execution by the processor, perform operations comprising:
- receiving a constellation which has unused constellation points;
- using a plurality of lookup tables for indicating whether a particular constellation point is used wherein unused constellation points are flagged and wherein a plurality of entries of the tables are the codewords of the actual constellation points;
- computing a euclidean distance to the immediate neighbors resulting from the immediate upper and lower integers for u and v:
- ū and v;
- selecting the upper or lower integer that corresponds to the smalling distance, if it is used in the constellation;
- and
Dependencies are inferred from the claim text.