Method and apparatus for reverse link loading estimation

• US 6,442,398 B1
• Filed: 09/30/1999
• Issued: 08/27/2002
• Est. Priority Date: 12/03/1998
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Padovani, Roberto, Judson, Bruce A.
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): CHOW, CHARLES CHIANG
• Application Number:
  US09/409,943
• Time in Patent Office: 1,062 Days
• Field of Search: 455/453, 455/522, 455/67.1, 455/423, 455/115, 370/252, 370/249, 370/342, 370/229
• US Class Current: 455/522
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/221 using past power control commands
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets

Abstract

In one embodiment of method and appartus for determining loading in a communication system, the communication system accumulates a power control commands series and corresponding transmit gain adjustments series between a base station and a designated remote station, under regular operating conditions. After transmissions form the remaining remote stations are interrupted, the communication system repeats the accumulation, and determines the loading according to the accumulated series. Alternatively, the communication system measures power of a test signal injected into base station receiver, under regular operating conditions. After transmissions form the remote stations are interrupted, the communication system repeats the measurement, and determines the loading according to the two measurements. Alternatively, the communication system measures gain of an AGC at the base station'"'"'s receiver, under regular operating conditions. After transmissions form the remote stations are interrupted, the communication system repeats the measurement, and determines the loading according to the two measurements.

Claims

1. A method of estimating loading in a wireless communication system, comprising the steps of:

entering a period of silence during which a designated remote unit continues to transmit;

performing closed loop power control on a reverse link signal received from said designated remote unit;

accumulating a first series of power control commands to produce a first transmit gain adjustment value;

resuming normal operation in which active remote units resume transmission of reverse link signals;

performing closed loop power control on said reverse link signal received from said designated remote unit;

accumulating a second series of power control commands to produce a second transmit gain adjustment value; and

determining a level of loading based upon said first and second transmit gain adjustment values.

2. The method of claim 1, wherein said period of silence occurs simultaneously among a group of base stations.

3. The method of claim 1, wherein said period of silence follows a silence command transmitted by a base station.

4. The method of claim 1, wherein said period of silence occurs periodically.

5. The method of claim 1, wherein said steps of performing closed loop power control comprise the step of transmitting said first and second series of power control commands to said designated remote unit.

6. The method of claim 1, wherein said steps of performing closed loop power control comprise the step of adjusting a transmission power of said reverse link signal by said designated remote unit.

7. The method of claim 1, wherein said steps of performing closed loop power control comprise the step of transmitting said first and second series of power control commands to said designated remote units.

8. The method of claim 1, further comprising the step of using said level of loading in an admission method which admits or denies access to said system.

9. The method of claim 1, further comprising the step of using said level of loading in a data rate determination method which controls a data rate at which remote units access said system.

10. The method of claim 1, wherein said level of loading is proportional to $\frac{\mathrm{TGA}}{}$

 



(t)-TGA

 



(0)TGA

 



(t)

wherein TGA(0) is equal to said first transmit gain adjustment value and wherein TGA(t) is equal to said second transmit gain adjustment value.

11. The method of claim 1, wherein said steps of accumulating are performed by a base station.

12. The method of claim 1, wherein said steps of accumulating are performed by said designated remote unit.

13. An apparatus for load estimation in a wireless communication system, comprising:

means for performing closed loop power control on a reverse link signal received from a designated remote unit;

means for entering a period of silence during which said designated remote unit continues to transmit;

means for accumulating a first series of power control commands to produce a first transmit gain adjustment value;

means for resuming normal operation in which active remote units resume transmission of reverse link signals;

means for accumulating a second series of power control commands to produce a second transmit gain adjustment value; and

means for determining a level of loading based upon said first and second transmit gain adjustment values.

14. The apparatus of claim 13, wherein said period of silence occurs simultaneously among a group of base stations.

15. The apparatus of claim 13, wherein said means for performing closed loop power control comprises means for remotely adjusting a transmission power of said reverse link signal.

16. The apparatus of claim 13, wherein said means for performing closed loop power control comprises means for transmitting said first and second series of power control commands to said designated remote units.

17. The apparatus of claim 13, further comprising means responsive to said level of loading for admitting or denying access to said system.

18. The apparatus of claim 13, further comprising means responsive to said level of loading for controlling a data rate at which remote units access said system.

19. The apparatus of claim 13, wherein said level of loading is proportional to $\frac{\mathrm{TGA}}{}$

 



(t)-TGA

 



(0)TGA

 



(t)

wherein TGA(0) is equal to said first transmit gain adjustment value and wherein TGA(t) is equal to said second transmit gain adjustment value.

20. The apparatus of claim 13, wherein said means for accumulating are incorporated in a base station.

21. The apparatus of claim 13, wherein said means for accumulating are incorporated in said designated remote unit.

22. A base station, comprising:

a demodulator receiving a remote test unit signal and producing a demodulated signal;

a signal quality determination block receiving said demodulated signal and producing an indication of quality thereof; and

a digital signal processor receiving said indication of quality and determining a power control command for said remote test unit, wherein said digital signal processor accumulates a first series of power control commands corresponding to said remote test unit during a period of silence, accumulates a second series of said power control commands corresponding to said remote test unit during a period of normal operation and determines a level of loading based upon said first and second series of power control commands.

23. A method of estimating loading in a wireless communication system, comprising the steps of:

(a) injecting, at a base station, a test signal prior to an automatic gain control;

(b) entering a period of silence during which all remote units cease transmission;

(c) accumulating, at said base station after said automatic gain control, said test signal to produce a first power value;

(d) resuming normal operation in which active remote units resume transmission;

(e) accumulating, at a base station after said automatic gain control, said test signal to produce a second power value; and

(f) determining a level of loading based upon said first and second power values.

24. The method of claim 23, wherein said period of silence follows a silence command transmitted by a base station.

25. The method of claim 23, wherein said period of silence occurs periodically.

26. The method of claim 23 further comprising a step of:

(a) repeating said steps (e) and (f) several times before resuming said step (b).

27. The method of claim 23, wherein said level of loading is proportional to $\frac{P_a-P_n}{P_a}$

wherein P_n is equal to said first power value and wherein P_a is equal to said second power value.

28. The method of claim 23, further comprising a step of:

(a) using said level of loading in an admission method which admits or denies access to said system.

29. The method of claim 23, further comprising a step of using said level of loading in a data rate determination method which controls a data rate at which remote units access said system.

43. The method of claim 23, wherein said level of loading is proportional $\frac{G_a-G_n}{G_a}$

wherein G_n is equal to said first gain setting and wherein G_a is equal to said second gain setting.

30. An apparatus for load estimation in a wireless communication system, comprising:

(a) means for injecting, at a base station, a test signal prior to an automatic gain control;

(b) means for entering a period of silence during which all remote units cease transmission;

(c) means for accumulating, at said base station after said automatic gain control, said test signal to produce a first power value;

(d) means for resuming normal operation in which active remote units resume transmission;

(e) means for accumulating, at said base station after said automatic gain control, said test signal to produce a second power value; and

(f) means for determining a level of loading based upon said first and second power values.

31. The apparatus of claim 30, wherein said means for entering period of silence act in a response to a silence command transmitted by a base station.

32. The apparatus of claim 30, wherein said means for entering period of silence act periodically.

33. The apparatus of claim 30 further comprising:

(a) means for invoking repeated use of said means (e) and (f) several times before invoking said means (b).

34. The apparatus of claim 30, wherein said level of loading is proportional to $\frac{P_a-P_n}{P_a}$

wherein P_n is equal to said first power value and wherein P_a is equal to said second power value.

35. The apparatus of claim 30, further comprising:

(a) means for using said level of loading in an admission method which admits or denies access to said system.

36. The apparatus of claim 30, further comprising:

(a) means for using said level of loading in a data rate determination method which controls a data rate at which remote units access said system.

37. A base station, comprising:

(a) a receiver, configured to receive signals from remote units;

(b) a transmitter, configured to transmit signals to said remote units;

(c) a test signal generator, communicatively coupled to a coupler for injecting a test signal to said receiver prior to an automatic gain control;

(d) a power level determination device, communicatively coupled to said automatic gain control; and

(e) a processor, communicatively coupled to said power level determination device and said transmitter, said processor having been configured to;

(i) provide a signal to said transmitter, said signal indicating a period of silence, and a period of normal operation;

(ii) accept from said power level determination device a first power level determined during said period of silence;

(iii) accept from said power level determination device a second power level determined during said period of normal operation; and

(iv) determine a level of loading loading based upon said first and second power values.

38. A remote station, comprising

(a) a receiver, configured to receive signals from base stations;

(b) a transmitter, configured to transmit signals to said base stations;

(c) a processor communicatively coupled to said receiver and said transmitter, said processor having been configured to;

(i) determine whether a signal provided by said receiver contain a command to enter a period of silence;

(ii) instruct said transmitter to cease transmission for said period of silence upon detection of said command; and

(iii) instruct said transmitter to resume transmission upon expiration of said period of silence.

39. A method of estimating loading in a wireless communication system, comprising the steps of:

(a) entering a period of silence during which all remote units cease transmission;

(b) evaluating, at a base station, a first gain setting of an automatic gain control;

(c) resuming normal operation in which active remote units resume transmission;

(d) evaluating, at said base station, a second gain setting of said automatic gain control; and

(e) determining a level of loading based upon said first and second gain settings.

40. The method of claim 39, wherein said period of silence follows a silence command transmitted by said base station.

41. The method of claim 39, wherein said period of silence occurs periodically.

42. The method of claim 39 further comprising a step of:

(b) repeating said steps (d) and (e) several times before resuming said step (a).

44. The method of claim 39, further comprising a step of:

(b) using said level of loading in an admission method which admits or denies access to said system.

45. The method of claim 39, further comprising a step of using said level of loading in a data rate determination method which controls a data rate at which remote units access said system.

46. An apparatus for load estimation in a wireless communication system, comprising:

(a) means for entering a period of silence during which all remote units cease transmission;

(b) means for evaluating, at a base station, a first gain setting of an automatic gain control;

(c) means for resuming normal operation in which active remote units resume transmission;

(d) means for evaluating, at said base station, a first gain setting of said automatic gain control; and

(e) means for determining a level of loading based upon said first and second gain settings.

47. The apparatus of claim 46, wherein said means for entering period of silence act in a response to a silence command transmitted by a base station.

48. The apparatus of claim 46, wherein said means for entering period of silence act periodically.

49. The apparatus of claim 46 further comprising:

(b) means for invoking repeated use of said means (d) and (f) several times before invoking said means (a).

50. The apparatus of claim 46, wherein said level of loading is proportional to $\frac{G_a-G_n}{G_a}$

wherein G_n is equal to said first gain setting and wherein G_a is equal to said second gain setting.

51. The apparatus of claim 46, further comprising:

(b) means for using said level of loading in an admission method which admits or denies access to said system.

52. The apparatus of claim 46, further comprising:

(b) means for using said level of loading in a data rate determination method which controls a data rate at which remote units access said system.

53. A base station, comprising:

(a) a receiver, configured to receive signals from remote units;

(b) a transmitter, configured to transmit signals to said remote units;

(c) an automatic gain control acting on a signal provided by said receiver; and

(d) a processor, communicatively coupled to said automatic gain control and said transmitter, said processor having been configured to;

(i) provide signals to said transmitter, said signals indicating a period of silence, and a period of normal operation;

(ii) evaluate during said period of silence, a first gain setting of said automatic gain control;

(iii) evaluate during said period of normal operation, a second gain setting of said automatic gain control; and

(iv) determine a level of loading based upon said first and second gain settings.