Systems, methods, and computer program products for controlling the error rate in a communication device by adjusting the distance between signal constellation points

• US 6,662,322 B1
• Filed: 10/29/1999
• Issued: 12/09/2003
• Est. Priority Date: 10/29/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ye, Hua, Ware, Malcolm Scott, Neeser, Fredy D., Dholakia, Ajay, Davis, Gordon Taylor, Hwang, Dongming, Abdelilah, Youssef
• Primary Examiner(s): Tu, Christine T.
• Assistant Examiner(s): Torres, Joseph D.
• Application Number:
  US09/430,700
• Time in Patent Office: 1,502 Days
• Field of Search: 714/704, 714/799, 714/811, 714/708, 375/222, 375/240.02
• US Class Current: 714/708
• CPC Class Codes: H04L 25/4917 using multilevel codes
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power

Abstract

Error rate control systems, methods, and computer program products request a data rate slow-down based on the status of the error rate. A linear penalty is generated if a data rate slow-down is requested, which is then used to determine a minimum distance between constellation points in a signaling constellation or alphabet. Because the minimum distance between constellation points may be directly related to the error probability, the error rate may be controlled through the linear penalty.

Claims

1. A system for controlling an error rate in a communication device, comprising:

means for requesting a data rate slow-down based on the error rate;

means for generating a linear penalty if the data rate slow-down is requested; and

means for determining a minimum distance between constellation points based on the linear penalty if the data rate slow-down is requested, the means for determining the minimum distance comprising;

means for setting the minimum distance to one of a lower bound and a current minimum distance between constellation points; and

means for multiplying the minimum distance by the linear penalty.

2. A system as recited in claim 1, further comprising:

means for monitoring data-link level errors to determine the error rate.

3. A system as recited in claim 2, wherein the means for monitoring comprises:

means for filtering the data-link level errors; and

means for comparing the filtered data-link level errors with a threshold; and

wherein the means for requesting comprises;

means for requesting the data rate slow-down if the filtered data-link level errors exceed the threshold.

4. A system as recited in claim 1, further comprising:

means for monitoring the mean squared error (MSE) to determine the error rate.

5. A system as recited in claim 4, wherein the means for monitoring comprises:

means for comparing the MSE with a threshold; and

wherein the means for requesting comprises;

means for requesting the data rate slow-down if the MSE exceeds the threshold.

6. A system as recited in claim 5, further comprising:

means for computing a sum of a penalty parameter plus an offset; and

wherein the means for generating the linear penalty comprises;

means for generating the linear penalty based on the sum of the penalty parameter plus the offset.

7. A system as recited in claim 1, wherein the means for requesting comprises:

means for requesting the data rate slow-down if the error rate exceeds a threshold; and

wherein the means for generating comprises;

means for incrementing a penalty parameter by a penalty step if the data rate slow-down is requested; and

means for generating the linear penalty based on the penalty parameter.

8. A system as recited in claim 1, wherein the means for generating comprises:

means for generating the linear penalty based on a penalty step parameter.

9. A system as recited in claim 8, wherein the penalty step parameter is about 0.5 dB.

10. A system as recited in claim 1, wherein the constellation points comprise pulse amplitude modulated (PAM) signaling levels.

11. A method of controlling an error rate in a communication device, comprising the steps of:

requesting a data rate slow-down based on the error rate;

generating a linear penalty if the data rate slow-down is requested; and

determining a minimum distance between constellation points based on the linear penalty if the data rate slow-down is requested, wherein determining the minimum distance comprises;

setting the minimum distance to one of a lower bound and a current minimum distance between constellation points; and

multiplying the minimum distance by the linear penalty.

12. A method as recited in claim 11, further comprising the step of:

monitoring data-link level errors to determine the error rate.

13. A method as recited in claim 12, wherein the steps of monitoring data-link level errors and requesting the data rate slow-down comprise the steps of:

filtering the data-link level errors;

comparing the filtered data-link level errors with a threshold; and

requesting the data rate slow-down if the filtered data-link level errors exceed the threshold.

14. A method as recited in claim 11, further comprising the step of:

monitoring a mean squared error (MSE) to determine the error rate.

15. A method as recited in claim 14, wherein the steps of monitoring the MSE and requesting the data rate slow-down comprise the steps of:

comparing the MSE with a threshold; and

requesting the data rate slow-down if the MSE exceeds the threshold.

16. A method as recited in claim 15, further comprising the step of:

computing a sum of a penalty parameter plus an offset; and

wherein the step of generating the linear penalty comprises the step of;

generating the linear penalty based on the sum of the penalty parameter plus the offset.

17. A method as recited in claim 11, wherein the step of requesting the data rate slow-down comprises the step of:

requesting the data rate slow-down if the error rate exceeds a threshold; and

wherein the step of generating the linear penalty comprises the steps of;

incrementing a penalty parameter by a penalty step if the data rate slow-down is requested; and

generating the linear penalty based on the penalty parameter.

18. A method as recited in claim 11, wherein the step of generating the linear penalty comprises the step of:

generating the linear penalty based on a penalty step parameter.

19. A method as recited in claim 18, wherein the penalty step parameter is about 0.5 dB.

20. A method as recited in claim 11, wherein the constellation points comprise pulse amplitude modulated (PAM) signaling levels.

21. A computer program product for controlling an error rate in a communication device, comprising:

a computer readable storage medium having computer readable program code embodied therein, the computer readable program code comprising;

computer readable program code for requesting a data rate slow-down based on the error rate;

computer readable program code for generating a linear penalty if the data rate slow-down is requested; and

computer readable program code for determining a minimum distance between constellation points based on the linear penalty if the data rate slow-down is requested, the computer readable program code for determining the minimum distance comprising;

computer readable program code for setting the minimum distance to one of a lower bound and a current minimum distance between constellation points; and

computer readable program code for multiplying the minimum distance by the linear penalty.

22. A computer program product as recited in claim 21, further comprising:

computer readable program code for monitoring data-link level errors to determine the error rate.

23. A computer program product as recited in claim 22, wherein the computer readable program code for monitoring comprises:

computer readable program code for filtering the data-link level errors;

computer readable program code for comparing the filtered data-link level errors with a threshold; and

wherein the computer readable program code for requesting comprises;

computer readable program code for requesting the data rate slow-down if the filtered data-link level errors exceed the threshold.

24. A computer program product as recited in claim 21, further comprising:

computer readable program code for monitoring the mean squared error (MSE) to determine the error rate.

25. A computer program product as recited in claim 24, wherein the computer readable program code for monitoring comprises:

computer readable program code for comparing the MSE with a threshold; and

wherein the computer readable program code for requesting comprises;

computer readable program code for requesting the data rate slow-down if the MSE exceeds the threshold.

26. A computer program product as recited in claim 25, further comprising:

computer readable program code for computing a sum of a penalty parameter plus an offset; and

wherein the computer readable program code for generating the linear penalty comprises;

computer readable program code for generating the linear penalty based on the sum of the penalty parameter plus the offset.

27. A computer program product as recited in claim 21, wherein the computer readable program code for requesting comprises:

computer readable program code for requesting the data rate slow-down if the error rate exceeds a threshold; and

wherein the computer readable program code for generating comprises;

computer readable program code for incrementing a penalty parameter by a penalty step if the data rate slow-down is requested; and

computer readable program code for generating the linear penalty based on the penalty parameter.

28. A computer program product as recited in claim 21, wherein the computer readable program code for generating comprises:

computer readable program code for generating the linear penalty based on a penalty step parameter.

29. A computer program product as recited in claim 28, wherein the penalty step parameter is about 0.5 dB.

30. A computer program product as recited in claim 21, wherein the constellation points comprise pulse amplitude modulated (PAM) signaling levels.