Average power control of wireless transmission having a variable duty cycle
View Patent ↗A method an apparatus for controlling a transmission signal power level of a transmitter is disclosed. The method includes receiving a root-mean-squared target power level. A duty cycle of a transmission signal is determined that indicates power on and power off periods over a predetermined sensing interval. A transmission signal power level is sensed. The transmission signal power level is adjusted to be approximately equal to the target power level divided by the duty cycle.
1. A method of controlling a transmission signal power level of a transmitter, comprising:
receiving a target power level;
determining duty cycle of a transmission signal that indicates power on and power off periods over a predetermined sensing interval;
sensing a transmission signal power level;
adjusting the transmission signal power level to be approximately equal to the target power level divided by the duty cycle:
receiving a transmission indicator that is active during transmission of signals;
at least sensing the transmission signal power level while the transmission indicator is active.
2. The method of claim 1 , wherein the target power level is a root-mean-squared target power level of −41.3 dBm/MHz over a 1 mS period.
3. The method of claim 1 , wherein the predetermined sensing interval is 1 mS.
4. The method of claim 1 , wherein the transmission signal power level is adjusted by an adjustable gain amplifier of a transmitter chain of the transmitter.
5. The method of claim 1 , wherein the transmission signal power level is adjusted after the predetermined sensing interval.
6. The method of claim 1 , wherein the transmission signal power level is adjusted while the transmission indicator is inactive.
7. The method of claim 1 , wherein sensing a transmission signal power level of the transmission signal comprises:
taking M measurements of a power level of a transmission packet;
computing a first instantaneous power level by averaging the M measurements.
8. The method of claim 7 , further comprising computing a second instantaneous power level of the transmission signal, comprising:
sensing the first instantaneous power level of N transmission packets; and
computing the second instantaneous power level by detecting the maximum of the first instantaneous power levels of the N transmission packets.
9. The method of claim 7 , further comprising computing a second instantaneous power level of the transmission signal, comprising:
sensing the first instantaneous power level of N transmission packets; and
computing the second instantaneous power level by averaging the first instantaneous power levels of the N transmission packets.
10. The method of claim 1 , wherein the duty cycle of the transmission signal is computed based on the power on-time divided by the sum of the power on-time and the power off-time.
11. The method of claim 1 , wherein the duty cycle of the transmission signal is provided by a transmission scheduler.
12. The method of claim 4 , wherein the adjustable gain amplifier comprises course gain adjustment settings and a fine gain adjustment.
13. The method of claim 12 , wherein the course adjustment settings are controlled by a scheduler, and the fine gain adjustment is controlled to maintain the transmission signal power level.
14. A UWB transmitter comprising:
a power detector for detecting an instantaneous power level of a transmission signal of the transmitter;
an adjustable gain amplifier for adjusting the instantaneous power level of the transmission signal;
a controller for receiving a target power level, and setting the adjustable gain amplifier, wherein the instantaneous power level is made substantially equal to the target power level divided by a duty cycle of the transmission signal;
taking M measurements of a power level of a transmission packet;
computing a first instantaneous power level by averaging the M measurements;
sensing the first instantaneous power level of N transmission packets; and
computing the instantaneous power level by detecting the maximum first instantaneous power level of the N transmission packets.
15. A UWB transmitter comprising:
a power detector for detecting an instantaneous power level of a transmission signal of the transmitter;
an adjustable gain amplifier for adjusting the instantaneous power level of the transmission signal;
a controller for receiving a target power level, and setting the adjustable gain amplifier, wherein the instantaneous power level is made substantially equal to the target power level divided by a duty cycle of the transmission signal;
taking M measurements of a power level of a transmission packet;
computing a first instantaneous power level by averaging the M measurements;
wherein sensing the instantaneous power level of the transmission signal, comprises:
sensing the first instantaneous power level of N transmission packets; and
computing the instantaneous power level averaging the first instantaneous power level of the N transmission packets.
16. The transmitter of claim 14 , wherein the duty cycle of the transmission signal is computed based on the power on-time divided by the sum of the power on-time and the power off-time.
17. The transmitter of claim 16 , wherein the duty cycle of the transmission signal is provided by a transmission scheduler.
18. The transmitter of claim 14 , wherein the target power level is a root-mean-squared target power level of −41.3 dBm/MHz over a 1 mS period.