Device and method for downlink gain compensation as well as radio unit comprising the device

Patent metadata

Field	Value
Publication number	US-11296658-B2
Application number	US-201816636858-A
Country	US
Kind code	B2
Filing date	Aug 13, 2018
Priority date	Aug 15, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

Device and method are disclosed for downlink gain compensation at a radio unit. According to an embodiment, the device comprises a pre-distortion circuit, a digital gain adjuster, a gain determiner and a first gain controller. The pre-distortion circuit is configured to generate and apply a pre-distortion to an input signal. The digital gain adjuster is configured to apply an adjustable gain to an output signal from the pre-distortion circuit. The gain determiner is configured to determine a gain difference between a target downlink gain and current downlink gain. The first gain controller is configured to control the digital gain adjuster based on the gain difference. A radio unit comprising the device is also disclosed.

First claim

What is claimed is:

1. A device
for use in a radio unit, RU, the device comprising:
a pre-distortion circuit configured to generate and apply a pre-distortion to an input signal;
a digital gain adjuster, GA, configured to apply an adjustable gain to an output signal from the pre-distortion circuit;
a gain determiner configured to determine a gain difference between a target downlink gain and current downlink gain; and
a first gain controller configured to control the digital GA based on the gain difference,
wherein the RU comprises:
an analog GA configured to apply an adjustable gain to an output from the digital GA; and
a second gain controller configured to perform a preliminary gain adjustment via the analog GA and then trigger the gain determiner to determine the gain difference.

2. The device according to claim 1 , wherein the first gain controller is further configured to control the analog GA via the second gain controller based on the gain difference.

3. The device according to claim 1 wherein the RU comprises:
a power amplifier, PA, configured to amplify an output from the analog GA; and
an observation receiver configured to process an output from the PA to feed back an observation signal to the pre-distortion circuit; and
wherein the gain difference is determined from:
a compensation gain corresponding to current working frequency and temperature;
a power difference between the observation signal and the input signal received by the pre-distortion circuit; and
residual gain and phase errors obtained from the pre-distortion circuit.

4. The device according to claim 2 , wherein the first gain controller is configured to control the digital GA by:
determining a first adjustment amount of the digital GA based on the gain difference;
determining a next gain of the digital GA based on the first adjustment amount and current applied gain of the digital GA; and
configuring the next gain to the digital GA.

5. The device according to claim 4 , wherein the first gain controller is configured to determine the first adjustment amount by:
comparing the gain difference with a preset first adjustment step of the digital GA;
when the gain difference is smaller than the first adjustment step, setting the first adjustment amount as the gain difference; and
when the gain difference is greater than or equals to the first adjustment step, setting the first adjustment amount as the first adjustment step.

6. The device according to claim 4 , wherein the first gain controller is configured to determine the next gain by:
comparing a first sum of the first adjustment amount and the current applied gain with an adjustment range of the digital GA;
when the first sum is greater than an upper limit of the adjustment range, setting the next gain as a difference between the first adjustment amount and a second adjustment step of the analog GA;
when the first sum is within the adjustment range, setting the next gain as the first sum; and
when the first sum is smaller than a lower limit of the adjustment range, setting the next gain as a second sum of the first adjustment amount and the second adjustment step.

7. The device according to claim 6 , wherein the first gain controller is configured to control the analog GA via the second gain controller by:
when the first sum is greater than the upper limit of the adjustment range, setting a second adjustment amount of the analog GA as the second adjustment step;
when the first sum is smaller than the lower limit of the adjustment range, setting the second adjustment amount as an opposite value of the second adjustment step; and
configuring the second adjustment amount to the analog GA via the second gain controller.

8. A method implemented at a device for use in a radio unit, RU, wherein the device comprises a pre-distortion circuit configured to generate and apply a pre-distortion to an input signal, and a digital gain adjuster, GA, configured to apply an adjustable gain to an output signal from the pre-distortion circuit, the method comprising:
determining a gain difference between a target downlink gain and current downlink gain; and
controlling the digital GA based on the gain difference,
wherein the RU comprises:
an analog GA configured to apply an adjustable gain to an output from the digital GA; and
a second gain controller configured to perform a preliminary gain adjustment via the analog GA, wherein the gain difference is determined in response to a trigger signal from the second gain controller.

9. The method according to claim 8 , further comprising:
controlling the analog GA via the second gain controller based on the gain difference.

10. The method according to claim 8 , wherein the RU comprises:
a power amplifier, PA, configured to amplify an output from the analog GA; and
an observation receiver configured to process an output from the PA to feed back an observation signal to the pre-distortion circuit; and
wherein the gain difference is determined from:
a compensation gain corresponding to current working frequency and temperature;
a power difference between the observation signal and the input signal received by the pre-distortion circuit; and
residual gain and phase errors obtained from the pre-distortion circuit.

11. The method according to claim 9 , wherein controlling the digital GA comprises:
determining a first adjustment amount of the digital GA based on the gain difference;
determining a next gain of the digital GA based on the first adjustment amount and current applied gain of the digital GA; and
configuring the next gain to the digital GA.

12. The method according to claim 11 , wherein determining the first adjustment amount comprises:
comparing the gain difference with a preset first adjustment step of the digital GA;
when the gain difference is smaller than the first adjustment step, setting the first adjustment amount as the gain difference; and
when the gain difference is greater than or equals to the first adjustment step, setting the first adjustment amount as the first adjustment step.

13. The method according to claim 11 , wherein determining the next gain comprises:
comparing a first sum of the first adjustment amount and the current applied gain with an adjustment range of the digital GA;
when the first sum is greater than an upper limit of the adjustment range, setting the next gain as a difference between the first adjustment amount and a second adjustment step of the analog GA;
when the first sum is within the adjustment range, setting the next gain as the first sum; and
when the first sum is smaller than a lower limit of the adjustment range, setting the next gain as a second sum of the first adjustment amount and the second adjustment step.

14. The method according to claim 13 , wherein controlling the analog GA via the second gain controller comprises:
when the first sum is greater than the upper limit of the adjustment range, setting a second adjustment amount of the analog GA as the second adjustment step;
when the first sum is smaller than the lower limit of the adjustment range, setting the second adjustment amount as an opposite value of the second adjustment step; and
configuring the second adjustment amount to the analog GA via the second gain controller.

15. A device for use in a radio unit, RU, the device comprising:
a pre-distortion circuit configured to generate and apply a pre-distortion to an input signal;
a digital gain adjuster, GA, configured to apply an adjustable gain to an output signal from the pre-distortion circuit;
a device controller com

Assignees

• Ericsson Telefon Ab L M

Inventors

• Liu Peng
• Liu Yahui
• Jie Junfeng
• Wen Gan
• Liu Guangfeng

Classifications

• H03F1/3247 Primary

  using feedback acting on predistortion circuits (H03F1/3264 takes precedence) · CPC title

• H03F1/30

  Modifications of amplifiers to reduce influence of variations of temperature or supply voltage {or other physical parameters (in differential amplifiers H03F3/45479)} · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03G2201/103

  being an amplifying element · CPC title

• H03F2200/129

  there being a feedback over the complete amplifier · CPC title