Automatic gain control for beamformed signals

1. A method of selecting an RF gain of an automatic gain control amplifier, the method comprising:

measuring a strength of a received signal, the received signal at least at times having reliable and consistent power characteristics;

measuring an interference level of the received signal; and

based on a ratio of the measured signal strength to the measured interference level, determining one of:

a target output power level; and

a target output interference power level; and

determining a gain that, when applied to an incoming signal, will produce a corresponding one of:

the determined target output power level; and

the determined target output interference power level.

2. The method according to claim 1 , wherein the target output power level determining step comprises:

setting the target output power level to a first value when the measured signal strength divided by the measured interference level falls below a first threshold value; and

setting the target output power level to a second value when the measured signal strength divided by the measured interference level exceeds a second threshold value, wherein the first value is less than the second value.

3. The method according to claim 2 , further comprising:

determining a continuous transition between the first value and the second value.

4. The method according to claim 3 , which further comprises:

determining the transition by the formula (S High -S Low )/((C/I) High - (C/I) Low ), where S High is the target output power level when the ratio of the measured signal strength to the measured interference level exceeds the second threshold value, S Low is the target output power level when the ratio of the measured signal strength to the measured interference level is less than the first threshold value, (C/I) High being the second threshold value, and (C/I) Low being the first threshold value.

5. The method according to claim 1 , wherein the target interference output power level determining step comprises:

setting the target interference output power level to a first value when the measured signal strength divided by the measured interference level falls below a first threshold value; and

setting the target interference output power level to a second value when the measured signal strength divided by the measured interference level exceeds a second threshold value, wherein the first value is less than the second value.

6. The method according to claim 5 , further comprising:

determining a continuous transition between the first value and the second value.

7. The method according to claim 6 , which further comprises:

determining the transition slope by the formula (I High -I Low )/((C/I) High -(C/I) Low ), where I High is the target interference power output level when the ratio of the measured signal strength to the measured interference level exceeds the second threshold value, I Low is the target interference power output level when the ratio of the measured signal strength to the measured interference level is less than the first threshold value, (C/I) High being the second threshold value, and (C/I) Low being the first threshold value.

8. The method according to claim 1 , which further comprises:

providing the automatic gain control amplifier with:

an RF receiver;

an analog-to-digital converter communicatively coupled with and disposed downstream from the RF receiver; and

a digital receiver communicatively coupled with and disposed downstream from the analog-to-digital converter;

measuring the signal strength at an output of the analog-to-digital converter; and

measuring the interference level at the output of the analog-to-digital converter.

9. A communication device including an automatic gain control system comprising:

an RF receiver;

an analog-to-digital converter communicatively coupled with and disposed downstream from the RF receiver;

a digital receiver communicatively coupled with and disposed downstream from the analog-to-digital converter;

a first meter operable to measure a strength of a received signal, the signal having reliable and consistent power characteristics;

a second meter located downstream from the analog-to-digital converter and operable to measure an interference level of the received signal; and

a processor operable to:

based on a ratio of the measured signal strength of the signal to the measured interference level, determine one of:

a target output power level; and

a target output interference power level; and

determine a gain that, when applied to an incoming signal, will produce a corresponding one of:

the determined target output power level; and

the determined target output interference power level.

10. The communication device according to claim 9 , wherein the processor is further operable to:

set the target output power level to a first value when the measured signal strength divided by the measured interference level falls below a first threshold value; and

set the target output power level to a second value when the measured signal strength divided by the measured interference level exceeds a second threshold value, wherein the first value is less than the second value.

11. The communication device according to claim 10 , wherein the processor is further operable to:

determine a continuous transition between the first value and the second value.

12. The communication device according to claim 11 , wherein the processor is further operable to:

determine the transition slope by the formula (S High -S Low )/((C/I) High -(C/I) Low ), where S High is the target output power level when the ratio of the measured signal strength to the measured interference level exceeds the first threshold value, S Low is the target output power level when the ratio of the measured signal strength to the measured interference level is less than the second threshold value, (C/I) High is the first threshold value, and (C/I) Low is the second threshold value.

13. The communication device according to claim 9 , wherein the processor is further operable to:

set the target interference output power level to a first value when the measured signal strength divided by the measured interference level falls below a first threshold value; and

set the target interference output power level to a second value when the measured signal strength divided by the measured interference level exceeds a second threshold value, wherein the first value is greater than the second value.

14. The communication device according to claim 9 , wherein the processor is further operable to:

determine a continuous transition between the first value and the second value.

15. The communication device according to claim 9 , wherein the processor is further operable to:

determine the transition slope by the formula (I High -I Low )/((C/I) High -(C/I) Low ), where I High is the target interference power output level when the ratio of the measured signal strength to the measured interference level exceeds the second threshold value, I Low is the target interference power output level when the ratio of the measured signal strength to the measured interference level is less than the first threshold value, (C/I) High being the second threshold value, and (C/I) Low being the first threshold value.

16. The communication device according to claim 9 , wherein:

the interference level is measured at an output of the analog to digital converter.

17. A method of selecting an RF gain of an automatic gain control amplifier, the method comprising:

measuring a signal strength of a received preamble;

measuring an interference level of the received preamble; and

selecting an automatic gain control amplifier gain based on a ratio of the measured signal strength to the measured interference level;

wherein the gain selecting step comprises:

determining a target output power level based on the ratio of the measured signal strength to the measured interference level, and

determining a gain that, when applied to an incoming signal, will produce the target output power level; and

wherein the target determining step comprises:

setting a target to a first target value when the measured signal strength divided by the measured interference level falls below a first threshold value; and

setting the target to a second target value when the measured signal strength divided by the measured interference level exceeds a second threshold value, wherein the first target value is less than the second target value.

18. The method according to claim 17 , further comprising:

determining a continuous transition between the first target value and the second target value.