Method and apparatus to compensate quantization error of channel quality report

• US 20050170782A1
• Filed: 02/04/2004
• Published: 08/04/2005
• Est. Priority Date: 02/04/2004
• Status: Abandoned Application

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Ma, Lin, Rong, Zhigang
• Application Number:
  US10/771,938
• Publication Number:
  US 20050170782A1
• Time in Patent Office: Days
• US Class Current: 455/67.110
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0033 arrangements specific to the transmitter
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports

Abstract

In one aspect this invention provides a wireless communication system (5) that includes a mobile station (20) having circuitry (22, 24, 26) and a computer program controlling operation of the circuitry to make a measurement from a forward channel to obtain a measurement result value, to quantize the measurement result value in accordance with an N level quantization to obtain a code, and to report the code on a reverse channel. The wireless communication system further includes a base station (10) having circuitry (12, 14, 16) and a computer program controlling operation of the circuitry to convert the code to a number, to compare the number to a threshold and, if the comparison indicates that the number may not accurately reflect the measurement result value, to adjust the number using an adjustment factor. In these embodiments the adjustment factor, also referred to as Delta, may be a constant, or it may be a variable. In one embodiment Delta is computed by the mobile station, and is reported to the base station.

Claims

1. A method to determine a channel quality metric in a wireless communication system, comprising:

making a measurement from a forward channel to obtain a measurement result value, quantizing the measurement result value in accordance with an N level quantization to obtain a code, and reporting the code on a reverse channel;

converting the reported code to a number;

comparing the number to a threshold; and

if the comparison indicates that the number may not accurately reflect the measurement result value, adjusting the number using an adjustment factor.

2. A method as in claim 1, where the adjustment factor is a constant.

3. A method as in claim 1, where the wireless communications system comprises a base station and a mobile station, and where the adjustment factor has a value that is a function of a distance between the base station and the mobile station.

4. A method as in claim 1, where the wireless communications system comprises a base station and a mobile station, and where the adjustment factor has a value that is determined by the mobile station and reported to the base station.

5. A method as in claim 4, where the adjustment factor is computed by the mobile station by:

during a period of time when the obtained codes do not accurately reflect the actual measurement result values, determining a difference between individual ones of actual measurement result values and a threshold measurement result value;

averaging the difference values; and

reporting the average of the difference values as the adjustment factor to the base station.

6. A method as in claim 1, where N is equal to 16.

7. A method as in claim 1, where the threshold is equal to −

16.25 dB.

8. A method as in claim 5, where the threshold measurement result value is equal to −

15.5 dB.

9. A method as in claim 1, where making a measurement from the forward channel measures a pilot channel.

10. A method as in claim 9, where making a measurement determines a value for (Ec/Nt)_Pilot.

11. A method as in claim 4, where reporting the value of the adjustment factor to the base station occurs at intervals that are longer than intervals between the mobile station making a full channel quality indicator (CQI) report to the base station.

12. A method as in claim 5, where reporting the average of the difference values as the adjustment factor to the base station occurs at intervals that are longer than intervals between the mobile station making a full channel quality indicator (CQI) report to the base station.

13. A method as in claim 4, where reporting the value of the adjustment factor to the base station occurs at intervals that are specified to the mobile station in signaling received from the base station.

14. A wireless communication system, comprising:

a mobile station comprising circuitry and a computer program controlling operation of the circuitry to make a measurement from a forward channel to obtain a measurement result value, to quantize the measurement result value in accordance with an N level quantization to obtain a code, and to report the code on a reverse channel; and

a base station comprising circuitry and a computer program controlling operation of the circuitry to convert the code to a number, to compare the number to a threshold and, if the comparison indicates that the number may not accurately reflect the measurement result value, to adjust the number using an adjustment factor.

15. A wireless communication system as in claim 14, where the adjustment factor is a constant.

16. A wireless communication system as in claim 14, where the adjustment factor has a value that is a function of a distance between the base station and the mobile station.

17. A wireless communication system as in claim 14, where the adjustment factor has a value that is determined by the mobile station and reported to the base station.

18. A wireless communication system as in claim 17, where the circuitry and the computer program controlling operation of the circuitry of the mobile station determines the value of the adjustment factor by being responsive to a period of time when the obtained codes do not accurately reflect the actual measurement result values to determine a difference between individual ones of actual measurement result values and a threshold measurement result value;

to average the difference values; and

to report the average of the difference values as the adjustment factor to the base station.

19. A wireless communication system as in claim 14, where N is equal to 16.

20. A wireless communication system as in claim 14, where the threshold is equal to −

16.25 dB.

21. A wireless communication system as in claim 18, where the threshold measurement result value is equal to −

15.5 dB.

22. A wireless communication system as in claim 14, where the mobile station circuitry and computer program controlling operation of the circuitry makes a measurement from a pilot channel.

23. A wireless communication system as in claim 14, where the mobile station circuitry and computer program controlling operation of the circuitry determines a value for (Ec/Nt)_Pilot.

24. A wireless communication system as in claim 17, where the mobile station reports the value of the adjustment factor to the base station at intervals that are longer than intervals between the mobile station making a full channel quality indicator (CQI) report to the base station.

25. A wireless communication system as in claim 17, where the mobile station reports the average of the difference values as the adjustment factor to the base station at intervals that are longer than intervals between the mobile station making a full channel quality indicator (CQI) report to the base station.

26. A wireless communication system as in claim 17, where the mobile station reports the value of the adjustment factor to the base station at intervals that are specified to the mobile station in signaling received from the base station.

27. A network infrastructure component of a wireless communication system, comprising circuitry and a computer program controlling operation of the circuitry to receive a code from a mobile station, the code being indicative of a quantized result of a measurement result value obtained from a forward channel, to convert the code to a number, to compare the number to a threshold and, if the comparison indicates that the number may not accurately reflect the measurement result value, to adjust the number using an adjustment factor.

28. A network infrastructure component as in claim 27, where the adjustment factor is a constant.

29. A network infrastructure component as in claim 27, where the adjustment factor has a value that is a function of a distance between a base station and the mobile station.

30. A network infrastructure component as in claim 27, where the adjustment factor has a value that is determined by the mobile station and reported to a base station.

37. Wireless network apparatus as in claim 27, where the adjustment factor has a value that is one of a constant;

a function of a distance between a base station and the mobile station; and

determined by the mobile station and reported to a base station.

31. A mobile station component of a wireless communication system, comprising circuitry and a computer program controlling operation of the circuitry to make a measurement from a forward channel to obtain a measurement result value, to quantize the measurement result value in accordance with an N level quantization to obtain a code, to report the code on a reverse channel to a wireless communication system infrastructure component, and to determine a value of an adjustment factor for use by the infrastructure component when processing the code by being responsive to a period of time when the obtained codes do not accurately reflect actual measurement result values to determine a difference between individual ones of actual measurement result values and a threshold measurement result value, to average the difference values and to report the average of the difference values as the adjustment factor to the infrastructure component.

32. A mobile station component as in claim 31, where N is equal to 16 and where the threshold measurement result value is equal to −

15.5 dB.

33. A mobile station component as in claim 31, where the measurement is made from a pilot channel to determine a value for (Ec/Nt)_Pilot.

34. A mobile station component as in claim 31, where the mobile station component reports the value of the adjustment factor at intervals that are longer than intervals between the mobile station making a full channel quality indicator (CQI) report.

35. A mobile station as in claim 31, where the mobile station component reports the value of the adjustment factor at intervals that are specified to the mobile station component in signaling received from a base station.

36. Wireless network apparatus comprising means for receiving a code from a mobile station, the code being indicative of a quantized result of a measurement result value obtained from a forward channel, and for converting the code to a number, comparing the number to a threshold and, if the comparison indicates that the number may not accurately reflect the measurement result value, for adjusting the number using an adjustment factor.

38. Wireless network apparatus comprising means for making a measurement from a received channel to obtain a measurement result value;

means for quantizing the measurement result value in accordance with an N level quantization to obtain a code; and

means for reporting the code to a wireless communication system infrastructure component, further comprising means for determining a value of an adjustment factor for use by the infrastructure component when processing the code, said value determining means being responsive to an occurrence of a period of time when an obtained code does not accurately reflect actual measurement result values for determining a difference between individual ones of actual measurement result values and a threshold measurement result value, for averaging the difference values and for reporting the average of the difference values as the adjustment factor to the infrastructure component.

39. Wireless network apparatus as in claim 38, where the measurement is made from a pilot channel for determining a value for (Ec/Nt)_Pilot.

40. Wireless network apparatus as in claim 38, where said value determining means reports the value of the adjustment factor at intervals that are at least one of:

longer than intervals between making a full channel quality indicator (CQI) report; and

specified to the mobile station component in signaling received from a base station.