Constellation selection in a communication system

• US 7,274,735 B2
• Filed: 10/18/2002
• Issued: 09/25/2007
• Est. Priority Date: 02/28/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bitran, Yigal, Sommer, Naftali, Reznic, Zvi, Lusky, Itay, Haim, Eli, Bendel, Yosef, Shalvi, Ofir, Wajcer, Daniel, Yagil, Ariel
• Primary Examiner(s): Ghayour; Mohammed
• Assistant Examiner(s): MALEK, LEILA
• Application Number:
  US10/273,558
• Publication Number:
  US 20030179768A1
• Time in Patent Office: 1,803 Days
• Field of Search: 455/213, 455/296, 375/227, 375/340, 708/322, 381/94.1
• US Class Current: 375/227
• 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 for automatically estimating performance of a channel in a communication system if a different order constellation is used comprising:

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 the 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;

providing for output the beginning of the noise event and the end of the noise event;

wherein the 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; and

estimating channel performance based on 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 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.

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

6. The method of claim 1 further comprising:

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

providing for output the total number of noise events; and

estimating channel performance based on the total number of the noise events.

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

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

8. A system for identifying a duration of noise events to automatically estimate channel performance in a communication system if a different order constellation is used comprising:

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

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 the noise event when the signal noise is less than a predefined second threshold;

wherein the 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; and

an estimator for estimating channel performance based on the identification of the noise events.

9. The system of claim 8 wherein transmission is occurring on the channel at the current constellation.

10. The system of claim 8 wherein the predefined first threshold and the predefined second threshold are different values.

11. The system of claim 8 wherein the 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.

12. The system of claim 8 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.

13. The system of claim 8 further comprising:

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

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.

14. The system of claim 13 further comprising a plurality of accumulators coupled to the symbol translation module for use in simulating a deinterleaver.

16. A method for automatically estimating performance of a channel in a communication system comprising:

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

identifying an end of the noise event in the received signal when the noise in the received signal is less than a predefined second threshold, wherein transmission of signals is occurring on the channel at a first order constellation; and

estimating the performance of the channel when a second order constellation is used, wherein the beginning of the noise event is not identified until the noise is greater than the predefined first threshold for a first predetermined number of samples of the received signal.

17. A method according to claim 16, wherein the 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.

18. A method according to claim 16, wherein the predefined first threshold and the predefined second threshold are different values.

19. A method according to claim 16, wherein the received signal is processed through a slicer having an output signal, and the noise is determined by taking a difference between received signal and the output signal.

20. A method according to claim 16, further comprising:

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

providing the total number of noise events.

21. A method according to claim 16, the performance of the channel is estimated while transmission of a preamble is occurring on the channel.