Slicing algorithm for multi-level modulation equalizing schemes

• US 20050220220A1
• Filed: 03/03/2003
• Published: 10/06/2005
• Est. Priority Date: 03/19/2002
• Status: Active Grant

• Current Assignee: Magnolia Licensing LLC (IP Edge LLC)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Belotserkovsky, Maxim B
• Granted Patent: US 7,894,513 B2
• Time in Patent Office: Days
• US Class Current: 375/316
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H04L 2025/0342 QAM
• CPC Class Codes: H04L 2025/0363 Feature restoration, e.g. constant modulus
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/3809 Amplitude regulation arrangements

Abstract

A method for slicing a received signal includes the steps of receiving a signal representing one of a constellation of ideal data points in a planar signal space, the received signal being at a point in the signal space, and assigning to the received signal a decision point having a predetermined magnitude and an angle representing a corresponding ideal signal point. A slicer includes a source for receiving a signal representing one of a constellation of ideal data points in a planar signal space, the received signal being at a point in the signal space, and circuitry, coupled to the signal source, for generating a signal representing a decision point having a predetermined magnitude and an angle representing an ideal signal point corresponding to the signal point.

Claims

1. A method for slicing a received signal, comprising the steps of:

receiving a signal representing one of a constellation of ideal signal points in a planar signal space, the received signal being at a point in the signal space; and

assigning to the received signal a decision point having a predetermined magnitude and an angle representing a corresponding ideal signal point.

2. The method of claim 1 wherein the predetermined magnitude is equal to the magnitude of the average power of the constellation of ideal points.

3. The method of claim 1 wherein the angle representing the corresponding ideal signal point is equal to the angle of the corresponding ideal signal point.

4. The method of claim 1 wherein the assigning step comprises the steps of:

defining decision regions comprising respective neighborhoods around associated decision points;

determining the decision region in which the received signal point lies;

assigning the decision point associated with the determined decision region to the received data point.

5. The method of claim 4 wherein the step of defining decision regions comprises the steps of:

defining neighborhoods around corresponding ideal signal points as respective decision regions; and

associating a decision point with each decision region.

6. The method of claim 5 wherein the step of defining neighborhoods comprises the step of defining rectangular regions around the corresponding ideal signal point.

7. The method of claim 5 wherein the step of defining neighborhoods comprises the step of defining circular sectors containing the corresponding ideal signal point.

8. The method of claim 5 wherein the step of associating a decision point with each decision region comprises the step of associating a decision region with a decision point having the predetermined magnitude and the angle of the ideal signal point corresponding to the decision region.

9. The method of claim 4 wherein the step of defining decision regions comprises the steps of:

determining angles representing respective points in the constellation of ideal signal points specifying angles of boundaries between the angles representing the respective points in the constellation of ideal signal points;

defining decision regions as respective regions between adjacent boundary angles each containing one or more ideal signal points and one associated decision point.

10. The method of claim 7 wherein the specifying step comprises the step of specifying the boundary angles to be bisectors between adjacent angles representing respective points in the constellation of ideal signal points as boundary angles.

11. The method of claim 7 wherein the step of determining the decision region in which the received signal point lies comprises the steps of:

determining the angle of the received signal point; and

determining the decision region containing the angle of the received signal point.

12. The method of claim 11 wherein the angle of the received signal point is calculated as Arctan wherein S_I is the component of the received signal point on the in-phase axis and S_Q is the component of the received signal point on the quadrature axis.

13. A slicer, comprising:

a source for receiving a signal representing one of a constellation of ideal signal points in a planar signal space, the received signal being at a point in the signal space; and

circuitry, coupled to the signal source, for generating a signal representing a decision point having a predetermined magnitude and an angle representing an ideal signal point corresponding to the signal point.

14. The slicer of claim 13 wherein the generating circuitry comprises circuitry for generating a decision point representative signal having a magnitude equal to the magnitude of the average energy of the constellation of ideal data points.

15. The slicer of claim 13 wherein the generating circuitry comprises circuitry for generating a decision point representative signal having an angle equal to the angle of the corresponding ideal signal point.

16. The slicer of claim 13 wherein the generating circuitry comprises a look-up table having an input responsive to the received signal and an output the decision point representative signal.

17. The slicer of claim 16 wherein the look-up table is partitioned such that input signals representing points in a decision region produce a decision point representative output signal having the value of the decision point corresponding to the received signal point.

18. The slicer of claim 17 wherein decision regions are neighborhoods around respective ideal signal points in the constellation.

19. The slicer of claim 18 wherein decision regions are circular sectors containing respective ideal signal points in the constellation.

20. The slicer of claim 18 wherein decision regions are rectangular regions around respective ideal signal points in the constellation.

21. The slicer of claim 13 wherein the generating circuitry comprises:

circuitry for generating respective signals representing the locations of boundaries of decision regions being neighborhoods around associated decision points;

circuitry for generating a signal representing the location of the received signal point;

circuitry for comparing the signal representing the location of the received signal point to the signals representing the locations of decision region boundaries; and

circuitry for generating a signal representing the decision point associated with the decision region containing the received signal point.

22. The slicer of claim 21 wherein:

the circuitry for generating boundary representative signals generates respective signals representing angles of boundaries;

the circuitry for generating the received signal location representative signal comprises circuitry for generating a signal representing the angle of the received signal; and

the comparing circuitry compares the signal representing the angle of the received signal to the respective signals representing the angles of the boundaries.

23. The slicer of claim 22 wherein:

the received signal source generates a signal S_I representing the in-phase component of the received signal and a signal S_Q representing the quadrature component of the received signal; and

the circuitry for generating the received signal location angle representative signal generates a signal equal to Arctan.

24. The slicer of claim 22 wherein the circuitry for generating boundary representative signals generates signals representing angles between respective angles of the constellation of ideal data points.

25. The slicer of claim 24 wherein the circuitry for generating boundary representative signals generates signals representing bisectors of the respective angles of the constellation of ideal data points.