Method and apparatus for automatic gain control of a wireless receiver

• US 20050031058A1
• Filed: 07/09/2004
• Published: 02/10/2005
• Est. Priority Date: 07/14/2003
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Soong, Anthony C.K., Purdy, David, Flowers, Larry
• Granted Patent: US 7,349,501 B2
• Time in Patent Office: Days
• US Class Current: 375/345
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence

Abstract

A method and apparatus for automatic gain control of a receiver provides compensation of gain control operations for received signal disruptions. In one embodiment, an automatic gain control circuit remembers control state information from a time just before a given disruption, and uses it to reset the automatic gain control circuit at the end of the disruption, or to maintain the automatic gain control circuit during the disruption. The remembering function may be triggered, such by detecting an impending disruption, or done periodically at a high enough update rate that the remembered information is always current with respect to any given disruption. Thus, an exemplary automatic gain control circuit may generate a receiver gain control signal by filtering received signal power measurements, and compensate the generation of that gain control signal by capturing filter state information just prior to signal disruptions. Compensation may comprise resetting or freezing the filter.

Claims

1. A method of automatic gain control at a wireless communication receiver comprising:

varying receiver gain via an automatic gain control circuit that is responsive to a received signal; and

compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal.

2. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises resetting the automatic gain control circuit at the end of the disruption using control state information stored prior to the disruption.

3. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises freezing the automatic gain control circuit during the disruption using control state information stored prior to the disruption.

4. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises, for a silence period disruption, resetting the automatic gain control circuit at the end of the silence period using prior control state information stored before the silence period disruption began.

5. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises, for a silence period disruption, freezing the automatic gain control circuit over the silence period disruption using prior control state information stored before the silence period disruption began.

6. The method of claim 1, further comprising maintaining a running buffer of control state information for the automatic gain control circuit for use as the remembered control state information.

7. The method of claim 1, further comprising saving current control state information for the automatic gain control circuit at successive sample times, and using saved control state information from one or more sample times prior to a beginning of the disruption as the remembered control state information used to compensate the automatic gain control circuit.

8. The method of claim 7, further comprising detecting a start of the disruption, and using saved control information from the closest sample time before the detected start of the disruption as the remembered control state information used to compensate the automatic gain control circuit.

9. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises compensating the automatic gain control circuit for a silence period disruption in the received signal.

10. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises compensating the automatic gain control circuit for a jamming disruption in the received signal.

11. The method of claim 1, further comprising detecting if there is a disruption in the received signal and triggering said compensation of the automatic gain control circuit responsive thereto, said detection comprising at least one of detecting silence period disruptions and detecting jamming interruptions.

12. The method of claim 1, wherein varying receiver gain via an automatic gain control circuit that is responsive to a received signal comprises increasing or decreasing one or more receiver gains as needed to maintain signal samples derived from the received signal within a desired range.

13. The method of claim 12, wherein increasing or decreasing one or more receiver gains as needed to maintain signal samples derived from the received signal within a desired range comprises varying the receiver gain based on filtered power measurements obtained from the signal samples.

14. The method of claim 13, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises, at an end of the disruption, resetting a filter circuit used to obtain the filtered power measurements using remembered filter state information.

15. The method of claim 1, wherein compensating the automatic gain control circuit using remembered control state information if there is a disruption in the received signal comprises, at the end of the disruption, resetting filter state information for the automatic gain control circuit using stored filter state information from a time prior to the beginning of the disruption.

16. An automatic gain control circuit to provide automatic gain control for a wireless communication receiver, said automatic gain control circuit comprising one or more processing circuits configured to:

vary receiver gain responsive to a received signal; and

compensate for a disruption in the received signal using remembered control state information.

17. The automatic gain control circuit of claim 16, wherein the one or more processing circuits comprise a calculation circuit configured to generate signal measurements for the received signal, and a control circuit configured to vary the receiver gain as a function of the signal measurements.

18. The automatic gain control circuit of claim 17, wherein the control circuit includes a filter configured to generate one or more gain control signals operative to vary the receiver gain based on filtering the signal measurements, and further includes a compensation circuit configured to compensate for a disruption in the received signal using remembered control state information by resetting the filter circuit using one or more stored filter state values corresponding to a time prior to the disruption.

19. The automatic gain control circuit of claim 17, wherein the control circuit includes a filter configured to generate one or more gain control signals operative to vary the receiver gain based on filtering the signal measurements, and further includes a compensation circuit configured to compensate for a disruption in the received signal using remembered control state information by freezing the filter circuit using one or more stored filter state values corresponding to a time prior to the disruption.

20. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by resetting automatic gain control at the end of the disruption based on control state information stored prior to the disruption.

21. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by freezing automatic gain control during the disruption based on control state information stored prior to the disruption.

22. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by, for a silence period disruption, resetting automatic gain control at the end of the silence period using prior control state information stored before the silence period disruption began.

23. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by, for a silence period disruption, freezing automatic gain control over the silence period disruption using prior control state information stored before the silence period disruption began.

24. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to maintain a running buffer of control state information for the automatic gain control circuit for use as the remembered control state information.

25. The automatic gain control circuit of claim. 16, wherein the automatic gain control circuit is configured to save current control state information for the automatic gain control circuit at successive sample times, and use saved control state information from one or more sample times before a beginning of the disruption as the remembered control state information used to compensate for the disruption.

26. The automatic gain control circuit of claim 25, wherein the automatic gain control circuit is configured to detect a start of the disruption, and use saved control information from the closest sample time before the detected start of the disruption as the remembered control state information used to compensate for the disruption.

27. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by compensating automatic gain control for a silence period disruption in the received signal.

28. The automatic gain control circuit of claim. 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by compensating the automatic gain control circuit for a jamming disruption in the received signal.

29. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to detect the disruption and trigger said compensation responsive thereto, said detection comprising at least one of detecting silence period disruptions and detecting jamming interruptions.

30. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to vary receiver gain responsive to a received signal by increasing or decreasing one or more receiver gains as needed to maintain signal samples derived from the received signal within a desired range.

31. The automatic gain control circuit of claim 30, wherein the automatic gain control circuit is configured to vary the receiver gain based on filtered power measurements obtained from the signal samples.

32. The automatic gain control circuit of claim 31, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by, at an end of the disruption, resetting a filter circuit used to obtain the filtered power measurements using remembered filter state information.

33. The automatic gain control circuit of claim 16, wherein the automatic gain control circuit is configured to compensate for a disruption in the received signal using remembered control state information by, at the end of the disruption, resetting filter state information for the automatic gain control circuit using filter state information stored before a beginning of the disruption.

34. A method of automatic gain control at a wireless communication receiver comprising:

capturing an automatic gain control setting before a disruption in a received signal that is the subject of automatic gain control; and

temporarily using the captured automatic gain control setting to compensate automatic gain control for the disruption.

35. The method of claim 34, wherein capturing an automatic gain control setting before a disruption in a received signal that is the subject of automatic gain control comprises capturing filter state information for an automatic gain control circuit before a beginning of the disruption.

36. The method of claim 35, wherein capturing filter state information for an automatic gain control circuit before a beginning of the disruption comprises capturing filter state information at one or more times in advance of the disruption responsive to an indication that the disruption is impending.

37. The method of claim 35, wherein capturing filter state information for an automatic gain control circuit before a beginning of the disruption comprises capturing filter state information periodically, so that updated filter state information is available from one or more capture times that are in advance of the disruption.

38. A radio base station for use in a wireless communication network, the radio base station comprising:

one or more receivers configured to receive a reverse link signal as a received signal;

an automatic gain control circuit operatively associated with the one or more receivers and configured to;

vary a receiver gain responsive to the received signal; and

compensate automatic gain control of the one or more receivers for a disruption in the received signal using remembered control state saved for the automatic gain control circuit before a beginning of the disruption.

39. The radio base station of claim 38, wherein the automatic gain control circuit is configured to save control state information responsive to an indication that the disruption is impending.

40. The radio base station of claim 39, further comprising one or more base station processing circuits configured to generate the indication that the disruption is impending.

41. The radio base station of claim 38, wherein the automatic gain control circuit is configured to periodically save control state information at a desired update rate, so that remembered control state information is available from one or more update periods before the disruption.

42. The radio base station of claim 41, wherein the base station processing circuits are configured to measure reverse link loading during timed reverse link silence periods, and wherein the processing circuits generate the indication of impending received signal disruption in advance of each timed silence period, so that the automatic gain control circuit is compensated for silence period disruptions of the received signal.