Automatic gain setting in a cellular communications system

• US 20020061763A1
• Filed: 09/14/2001
• Published: 05/23/2002
• Est. Priority Date: 11/21/2000
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Weissman, Haim
• Granted Patent: US 6,819,936 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A method for adjusting a power level in a communications network which includes a first plurality of signal-transmission-elements adapted to receive signals coupled to a second plurality of signal-transmission-elements adapted to transmit the signals, the method including de-activating at least some of the first plurality so that the signals are not received in the first plurality and de-activating at least some of the second plurality so that the signals are not transmitted from the second plurality. The method includes injecting a reference signal having a predetermined injected power level at the first plurality, receiving the reference signal at the second plurality, measuring a received power level of the reference signal at the second plurality, comparing the injected and received power levels, and, responsive to the comparison, setting a gain of at least one of the signal-transmission-elements comprised in the first and second pluralities.

Claims

1. A method for adjusting a radio-frequency (RF) power level in a cellular communications network, the network including a first plurality of signal-transmission-elements adapted to receive communication signals as a first variable-gain repeater coupled to a second plurality of signal-transmission-elements adapted to transmit the communication signals as a second variable-gain repeater, the method comprising:

de-activating at least some of the first plurality of signal-transmission-elements so that the communication signals are not received in the first plurality;

de-activating at least some of the second plurality of signal-transmission-elements so that the communication signals are not transmitted from the second plurality;

injecting a reference signal having a predetermined injected power level at the first plurality of signal-transmission-elements;

receiving the reference signal at the second plurality of signal-transmission-elements;

measuring a received power level of the reference signal at the second plurality of signal-transmission-elements;

comparing the injected and received power levels; and

responsive to the comparison, setting a gain of at least one of the signal-transmission-elements comprised in the first and second pluralities.

2. A method according to claim 1, and comprising:

activating the at least some of the first plurality of signal-transmission-elements;

receiving at the first plurality of signal-transmission-elements the communication signals from a first region;

activating the at least some of the second plurality of signal-transmission-elements; and

transmitting the communication signals to a second region from the second plurality of signal-transmission-elements.

3. A method according to claim 2, wherein the first region and the second region do not overlap.

4. A method according to claim 2, wherein injecting the reference signal comprises measuring the predetermined injected power level with a first detector, wherein measuring the received power level comprises measuring the received power level with a second detector, and wherein activating the at least some of the second plurality of signal-transmission-elements comprises activating a power amplifier and setting a power level output of the power amplifier responsive to a power-amplifier output measured by a third detector and the predetermined injected power level measured by the first detector and the received power level measured by the second detector.

5. A method according to claim 4, and comprising setting an alarm responsive to the power-amplifier level and the received power level.

6. A method according to claim 2, and comprising:

receiving the communication signals at a frequency outside a predetermined forward-intermediate-frequency (FWD-IF) band at the first plurality of signal-transmission-elements;

mixing the communication signals with a local oscillator (LO) signal so as to generate a forward IF signal within the FWD-IF band;

conveying the forward IF signal to the second plurality of signal-transmission-elements; and

mixing the forward IF signal with the LO signal so as to recover information in the communication signals at the second plurality of signal-transmission-elements.

7. A method according to claim 6, wherein injecting the reference signal comprises generating the reference signal at a reference frequency within the FWD-IF band.

8. A method according to claim 7, and comprising:

receiving the communication signals at a frequency outside a predetermined reverse-intermediate-frequency (REV-IF) band, different from the FWD-IF band, at the second plurality of signal-transmission-elements;

mixing the communication signals with the LO signal so as to generate a reverse IF signal within the REV-IF band;

conveying the reverse IF signal to the first plurality of signal-transmission-elements; and

mixing the reverse IF signal with the LO signal so as to recover information in the communication signals at the first plurality of signal-transmission-elements;

and wherein setting the gain of the one of the first plurality of signal-transmission-elements and the gain of the one of the second plurality of signal-transmission-elements comprises;

determining gain values at the reference frequency; and

extrapolating the gain values to the REV-IF band responsive to parameters of the first and second pluralities of signal-transmission-elements and of a cable coupling the pluralities.

9. A method according to claim 1, wherein the first plurality of signal-transmission-elements and the second plurality of signal-transmission-elements are coupled by a cable, and comprising determining an effective length and an effective loss of the cable responsive to the comparison.

10. A method according to claim 9, wherein the effective loss of the cable comprises a forward effective loss responsive to a forward-intermediate-frequency and a reverse effective loss responsive to a reverse-intermediate-frequency different from the forward-intermediate-frequency.

11. A method according to claim 1, and comprising:

broadcasting an expected-output-level value from the first plurality of signal-transmission-elements;

receiving the expected-output-level value at the second plurality of signal-transmission-elements; and

setting the gain of the at least one of the signal-transmission-elements comprised in the second plurality responsive to the expected-output-level value.

12. A method according to claim 1, wherein setting the gain comprises setting a forward-gain for the communication signals in a forward path comprised in the first and second pluralities, and setting a reverse-gain for the communication signals in a reverse path comprised in the first and second pluralities.

13. A method according to claim 12, wherein the forward-gain and the reverse-gain differ by a pre-determined value.

14. A method according to claim 1, wherein the first plurality of signal-transmission-elements receive the communication signals at a signal-reception-level, and wherein injecting the reference signal comprises injecting the reference signal at an injection-level substantially the same as the signal-reception-level.

16. Apparatus according to claim 15, wherein the switching circuitry is adapted to activate the at least some of the first plurality of signal-transmission-elements and the at least some of the second plurality of signal-transmission-elements so that the first plurality of signal-transmission-elements receives the communication signals from a first region and the second plurality of signal-transmission-elements transmits the communication signals to a second region.

17. Apparatus according to claim 16, wherein the first region and the second region do not overlap.

18. Apparatus according to claim 16, wherein the second plurality of signal-transmission-elements comprises a power amplifier, and comprising:

a first detector which is adapted to measure the predetermined injected power level;

a second detector which is adapted to measure the received power level; and

a third detector which is adapted to measure a power-amplifier-level output of the power amplifier, so that a power-amplifier level is set responsive to the power-amplifier-level output and the predetermined injected power level and the received power level.

19. Apparatus according to claim 18, and comprising an alarm which is activated responsive to the power-amplifier level and the received power level.

20. Apparatus according to claim 16, wherein:

the first plurality of signal-transmission-elements are adapted to receive the communication signals at a frequency outside a predetermined forward-intermediate-frequency (FWD-IF) band and to mix the communication signals with a local oscillator (LO) signal so as to generate a forward IF signal within the FWD-IF band; and

the second plurality of signal-transmission-elements are adapted to receive the forward IF signal and to mix the forward IF signal with the LO signal so as to recover information in the communication signals.

21. Apparatus according to claim 20, wherein the reference oscillator is adapted to generate the reference signal at a reference frequency within the FWD-IF band.

22. Apparatus according to claim 21, wherein:

the second plurality of signal-transmission-elements is adapted to receive the communication signals at a frequency outside a predetermined reverse-intermediate-frequency (REV-IF) band, different from the FWD-IF band, and to mix the communication signals with the LO signal so as to generate a reverse IF signal within the REV-IF band;

the first plurality of signal-transmission-elements is adapted to mix the reverse IF signal with the LO signal so as to recover information in the communication signals; and

the control circuitry is adapted to determine gain values at the reference frequency and to extrapolate the gain values to the REV-IF band responsive to parameters of the first and second pluralities of signal-transmission-elements and of a cable coupling the pluralities.

23. Apparatus according to claim 15, wherein the coupling comprises a cable, and wherein the control circuitry is adapted to determine an effective length and an effective loss of the cable responsive to the injected power level and the received power level.

24. Apparatus according to claim 23, wherein the effective loss of the cable comprises a forward effective loss responsive to a forward-intermediate-frequency and a reverse effective loss responsive to a reverse-intermediate-frequency different from the forward-intermediate-frequency.

25. Apparatus according to claim 15, wherein:

the first plurality of signal-transmission-elements are adapted to broadcast an expected-output-level value therefrom;

the second plurality of signal-transmission-elements are adapted to receive the expected-output-level value; and

the control circuitry is adapted to set the gain of the at least one of the signal-transmission-elements comprised in the second plurality responsive to the expected-output-level value.

26. Apparatus according to claim 15, wherein the first and second pluralities comprise:

forward-path-elements for the communication signals following a forward path from the first to the second plurality; and

reverse-path-elements for the communication signals following a reverse path from the second to the first plurality;

and wherein the control circuitry is adapted to set a forward-gain for the forward-path-elements and a reverse-gain for the reverse-path-elements.

27. Apparatus according to claim 26, wherein the forward-gain and the reverse-gain differ by a pre-determined value.

28. Apparatus according to claim 15, wherein the first plurality of signal-transmission-elements receive the communication signals at a signal-reception-level, and wherein the reference oscillator is adapted to inject the reference signal at an injection-level substantially the same as the signal-reception-level.

15. Apparatus for adjusting a radio-frequency (RF) power level in a cellular communications network, comprising:

a first plurality of signal-transmission-elements coupled as a first variable-gain repeater;

a second plurality of signal-transmission-elements coupled as a second variable-gain repeater;

a coupling connecting the first and second pluralities of signal-transmission-elements, which is adapted to convey communication signals therebetween;

a reference oscillator, which is adapted to inject a reference signal having a predetermined injected power level at the first plurality of signal-transmission-elements;

a receiver, which is adapted to measure a received power level of the reference signal at the second plurality of signal-transmission-elements;

switching circuitry, which is adapted to de-activate at least some of the first and second pluralities of signal-transmission-elements so that the reference signal is not radiated from the coupling and the first and second pluralities of signal-transmission-elements; and

control circuitry which is adapted, responsive to the injected power level and the received power level, to set a gain of one of the signal-transmission-elements comprised in the first and second pluralities.