Radio system and a method for relaying radio signals

• US 8,243,851 B2
• Filed: 04/01/2009
• Issued: 08/14/2012
• Est. Priority Date: 04/01/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: UBIDYNE, INC
• Inventors: Kenington, Peter
• Primary Examiner(s): Lee, Siu
• Application Number:
  US12/416,596
• Publication Number:
  US 20100254441A1
• Time in Patent Office: 1,231 Days
• Field of Search: 375/260, 375/267, 375/295, 375/299, 375/296, 375/285
• US Class Current: 375/296
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal
• CPC Class Codes: H03F 2200/204 A hybrid coupler being used at the output of an amplifier circuit
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602
• CPC Class Codes: H04B 7/061 using feedback from receiving side

Abstract

The present invention provides a radio system and a method for relaying radio signals. The radio system comprises at least one transmit path, a digital predistortion unit, a calibration unit and a feedback path. The feedback path is commonly used by the digital predistortion unit and the calibration unit with the present invention. The calibration signal is adapted to update at least one of phase and amplitude changes and the digital predistortion. The present invention further relates to a method for relaying radio signals. The method comprises updating the digital predistortion as well as an updating of the phase and amplitude changes. The updating of the digital predistortion and the updating of the phase and amplitude changes is implemented using a feedback signal. The present invention further relates to a computer program product for the manufacture of the radio system according to the invention. The present invention further relates to a computer program product for the execution of the method according to the present invention.

Claims

1. A radio system for relaying radio signals, the radio system comprising:

at least one transmit path adapted to forward a payload signal as a transmit signal,

at least one amplifier adapted to amplify the transmit signal,

at least one duplex filter adapted to separate the transmit signal as a relayed transmit signal from a receive signal,

a digital predistortion unit adapted to apply a digital predistortion to the payload signal for linearising a transfer characteristic of the radio system,

a calibration unit adapted to apply phase and amplitude changes to the at least one transmit path,

at least one coupler to extract coupled transmit signals extracted from the transmit signal,

a feedback path commonly used by the digital predistortion unit and the calibration unit for feeding back a selected one of the coupled transmit signals as a feedback signal,

at least one switch located in close proximity to an output of the at least one amplifier, the at least one switch being configured to switch between the coupled transmit signals and the relayed transmit signal relayed by the at least one duplex filter, thereby forwarding a selected one of the coupled transmit signals and the relayed transmit signal,

a multi-way switch located at a distance from the at least one transmit path, the multi-way switch being adapted to select said selected one of the coupled transmit signals and the relayed transmit signal as a feedback signal, wherein at least one of;

the phase and amplitude changes and the digital predistortion is adaptable using the feedback signal.

2. The radio system according to claim 1, wherein at least one of the phase and amplitude changes and the digital predistortions is adaptable using correlations of the payload signal and the feedback signal.

3. The radio system according to claim 1, wherein the feedback signal is concurrently used to update the phase and amplitude changes and to update the digital predistortions.

4. The radio system according to claim 1, further comprising a calibration update module for updating the phase and amplitude changes.

5. The radio system according to claim 1, further comprising a digital predistortion update module for updating the digital predistortion.

6. The radio system according to claim 1, wherein the at least one transmit path is terminated by an antenna element.

7. The radio system according to claim 1, wherein the at least one transmit path further comprises a digital to analogue converter.

8. The radio system according to claim 7, wherein the digital to analogue converter comprises a sigma delta digital to analogue converter.

9. The radio system according to claim 1, wherein the at least one transmit path further comprises an amplifier for amplifying the transmit signal.

10. The radio system according to claim 1, wherein the at least one transmit path further comprises a filter filtering the transmit signal.

11. The radio system according to claim 10, wherein the filter comprises a duplex filter.

12. The radio system according to claim 1, wherein the at least one transmit path further comprises a coupler for extracting the coupled transmit signals out of the transmit signal.

13. The radio system according to claim 1, further comprising a switch for forwarding the selected one of the coupled transmit signals as the feedback signal.

14. The radio system according to claim 1, wherein the feedback path further comprises an attenuator.

15. The radio system according to claim 1, wherein the feedback path further comprises an analogue to digital converter.

16. The radio system according to claim 15, wherein the analogue to digital converter comprises a sigma delta converter.

17. The radio system according to claim 1, wherein the transmit path further comprises an up-converter unit for up-converting the transmit signal.

18. The radio system according to claim 17, the up-converting unit further comprising a filtering element for filtering the transmit signal.

19. The radio system according to claim 1, wherein the feedback path further comprises a down-converter unit for down-converting the selected one of the coupled transmit signals.

20. The radio system according to claim 1, further comprising a splitter adapted to extract a portion from the coupled transmit signals.

21. The radio system according to claim 1, further comprising a power detector.

22. The radio system according to claim 21, wherein at least one of the following elements is implemented on a chip:

the calibration unit, the predistortion unit, a calibration update module, a digital predistortion update module, a digital to analogue converter, an analogue to digital converter and the power detector.

23. The radio system according to claim 22, wherein the chip comprises a digital signal processor (DSP).

31. Computer program product embodied on a non-transitory computer-readable medium and the computer-readable medium comprising executable instructions for the manufacture of the radio system according to claim 1.

24. A method for relaying radio signals, the method comprising:

providing a payload signal,

applying a digital predistortion to the payload signal,

applying phase and amplitude changes to at least one transmit path,

forwarding the payload signal as a transmit signal along the at least one transmit path,

extracting coupled transmit signals extracted from the transmit signal,

separating the transmit signal as a relayed transmit signal from a receive signal,

switching between the coupled transmit signals and the relayed transmit signal, thereby forwarding a selected one of the coupled transmit signals and the relayed transmit signal,

a multi-way switch located at a distance from the at least one transmit path, the multi-way switch being adapted to select said selected one of the coupled transmit signals and the relayed transmit signal as a feedback signal,

feeding back said selected one of coupled transmit signals as a feedback signal,

updating the digital predistortion in response to the feedback signal, and

updating the phase and amplitude changes in response to the feedback signal.

25. The method according to claim 24, wherein at least one of the updating of the digital predistortions and the updating the phase and amplitude changes comprises using correlation methods.

26. The method according to claim 24, wherein the forwarding of the payload signal as a transmit signal along the at least one transmit path further comprises:

digital to analogue converting the transmit signal,

amplifying the transmit signal,

filtering the transmit signal,

extracting a coupled transmit signal from the at least one transmit path.

27. The method according to claim 24, wherein the feeding back of the selected one of the coupled transmit signals as the feedback signal comprises:

attenuating at least one of the coupled transmit signals and the feedback signal,

analogue to digital converting the feedback signal yielding a base band feedback signal.

28. The method according to claim 24, wherein the feeding back of the selected one of the coupled transmit signals as the feedback signal comprises:

filtering the feedback signal.

29. The method according to claim 24, wherein the updating of the digital predistortion comprises:

comparing the payload signal and the base band feedback signal,

extracting differences between the payload signal and the base band feedback signal,

checking if the differences are below a threshold, and

updating the digital predistortion responsive to the checking.

30. The method according to claim 24, wherein the updating of the phase and amplitude changes comprises:

correlating the payload and the base band feedback signal,

extracting transmit deviations,

checking whether the transmit deviations are above a threshold, and

updating the phase and amplitude changes responsive to the checking.

32. Computer program product embodied on a non-transitory computer-readable medium and the computer-readable medium comprising executable instructions for the execution of the method for relaying radio signals according to claim 24.