Constellation selection in a communication system

• US 20030179768A1
• Filed: 10/18/2002
• Published: 09/25/2003
• Est. Priority Date: 02/28/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bitran, Yigal, Shalvi, Ofir, Sommer, Naftali, Reznic, Zvi, Lusky, Itay, Yagil, Ariel, Wajcer, Daniel, Haim, Eli, Bendel, Yosef
• Granted Patent: US 7,274,735 B2
• Time in Patent Office: Days
• US Class Current: 370/437
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0017 where the mode-switching is based on Quality of Service requirement
• CPC Class Codes: H04L 1/0019 in which mode-switching is based on a statistical approach
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A method is provided to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of: receiving an input signal from the channel; passing the input signal to a slicer having an output signal; determining signal noise by taking the difference between the input signal and output signal; identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold; identifying an end of a noise event when the signal noise is less than a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Claims

1. A method to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of:

a. receiving an input signal from the channel;

b. passing the input signal to a slicer having an output signal;

c. determining signal noise by taking the difference between the input signal and output signal;

d. identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold;

e. identifying an end of a noise event when the signal noise is less than a predefined second threshold; and

f. providing for output the beginning of the noise event and the end of the noise event.

2. The method of claim 1 wherein transmission is occurring on the channel at the current constellation.

3. The method of claim 1 wherein the predefined first threshold and the predefined second threshold are different values.

4. The method of claim 1 wherein a beginning of the noise event is not identified until the signal noise is greater than the predefined first threshold for a first predetermined number of samples of the input signal.

5. The method of claim 1 wherein an end of the noise event is not identified until the signal noise is less than the predefined first threshold for a second predetermined number of samples of the input signal.

6. The method of claim 1 further comprising the step of outputting a vector with the value 1 between the beginning of the noise event and the end of the noise event.

7. The method of claim 1 further comprising the steps of:

a. determining a total number of noise events that occurred in the signal; and

b. providing for output the total number of noise events.

8. The method of claim 1 wherein the steps of the method are performed while transmission of a preamble is occurring on the channel.

17. The system of claim 1 wherein transmission of a preamble is occurring on the channel.

9. A system to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising:

a. a receiver for receiving signals from the channel comprising a slicer for determining signal noise in the signal; and

b. an identification module coupled to the slicer for identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold and for identifying an end of a noise event when the signal noise is less than a predefined second threshold.

10. The system of claim 9 wherein transmission is occurring on the channel at the current constellation.

11. The system of claim 9 wherein the predefined first threshold and the predefined second threshold are different values.

12. The system of claim 9 wherein a beginning of the noise event is not identified until the signal noise is greater than the predefined first threshold for a first predetermined number of samples of the signal.

13. The system of claim 9 wherein an end of the noise event is not identified until the signal noise is less than the predefined first threshold for a second predetermined number of samples of the signal.

14. The system of claim 9 wherein the identification module outputs a vector with the value 1 between the beginning of the noise event and the end of the noise event.

15. The system of claim 9 further comprising:

a. a symbol translation module for translating the vector into Reed-Solomon symbols; and

b. a histogram generator unit coupled to the symbol translation module for processing the Reed-Solomon symbols and generating statistical data on the Reed-Solomon symbols that are erred.

16. The system of claim 15 further comprising a plurality of accumulators coupled to the symbol translation module for use in simulating a deinterleaver.