Method of and Equalizer for Equalizing a Radio Frequency Filter

• US 20120201176A1
• Filed: 10/19/2009
• Published: 08/09/2012
• Est. Priority Date: 10/19/2009
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Su, Youping, Miao, Qingyu, Zhang, Chunhui
• Application Number:
  US13/501,288
• Publication Number:
  US 20120201176A1
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04L 2025/0377 during the reception of training signals
• CPC Class Codes: H04L 25/03012 operating in the time domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

A method (300) of and an equalizer (104-1, 104-2) for equalizing an RF filter (106-1, 106-2) supporting a frequency band by utilizing an antenna calibration path having the RF filter (106-1, 106-2) in a Node B (100) in a TDD system are provided. The method (300) comprises the steps of obtaining (302) an amplitude and phase response of a calibration signal having a frequency in the frequency band, stepwise changing (304) the frequency of the calibration signal, determining (306) a transfer function of the RF filter (106-1, 106-2), and equalizing (308) the RF filter (106-1, 106-2) based on the determined transfer function of the RF filter (106-1, 106-2).

Claims

1-18. -18. (canceled)

19. A method of equalizing a Radio Frequency (RF) filter in a Node B in a Time Division Duplex (TDD) system, the RF filter supporting a frequency band and forming a portion of an antenna calibration path, the method comprising an equalization procedure comprising:

obtaining an amplitude and phase response of a calibration signal having a frequency in the frequency band by transmitting the calibration signal through the calibration path;

stepwise changing the frequency of the calibration signal by sweeping a Local Oscillator frequency on the calibration path by a predefined step until the amplitude and phase response of the calibration signal in the whole frequency band is obtained;

determining a transfer function of the RF filter based on the amplitude and phase response of the calibration signal in the whole frequency band;

equalizing the RF filter based on the determined transfer function of the RF filter.

20. The method of claim 19 wherein equalizing the RF filter based on the determined transfer function of the RF filter comprises:

determining a Finite Impulse Response (FIR) filter based on the determined transfer function of the RF filter;

using the FIR filter to equalize the RF filter.

21. The method of claim 20 wherein the FIR filter is located in one of:

a Remote Radio Unit (RRU) comprising the RF filter;

or

a Main Unit coupled to the RRU.

22. The method of claim 19 wherein the calibration path is a transmitting calibration path or a receiving calibration path.

23. The method of claim 19 further comprising executing the equalization procedure during a Guard Period between a Downlink Pilot Time Slot and an Uplink Pilot Time Slot in a frame after cell setup.

24. The method of claim 19 further comprising executing the equalization procedure during a cell setup procedure.

25. The method of claim 19 further comprising triggering the equalization procedure in response to a variation in temperature exceeding a predefined threshold in one of:

the RF filter;

or

a Remote Radio Unit comprising the RF filter.

26. The method of claim 19 wherein the TDD system is a Time Division-Synchronous Code Division Multiple Access system or a Time Division-Long Term Evolution system.

27. An equalizer for equalizing a Radio Frequency (RF) filter in a Node B in a Time Division Duplex (TDD) system, the RF filter supporting a frequency band and forming a portion of an antenna calibration path, the equalizer configured to perform an equalization procedure that comprises:

obtaining an amplitude and phase response of a calibration signal having a frequency in the frequency band by transmitting the calibration signal through the calibration path;

stepwise changing the frequency of the calibration signal by sweeping a Local Oscillator frequency on the calibration path by a predefined step until the amplitude and phase response of the calibration signal in the whole frequency band is obtained;

determining a transfer function of the RF filter based on the amplitude and phase response of the calibration signal in the whole frequency band;

equalizing the RF filter based on the determined transfer function of the RF filter.

28. The equalizer of claim 27:

wherein the equalization procedure comprises determining a Finite Impulse Response (FIR) filter based on the determined transfer function of the RF filter;

wherein the equalizing the RF filter comprises equalizing the RF filter based on the FIR filter.

29. The equalizer of claim 28 wherein the FIR filter is located in a Remote Radio Unit comprising the RF filter or a Main Unit coupled to the RRU.

30. The equalizer of claim 27 wherein the calibration path is a transmitting calibration path or a receiving calibration path.

31. The equalizer of claim 27 wherein the equalizer is configured to perform the equalization procedure during a Guard Period between a Downlink Pilot Time Slot and an Uplink Pilot Time Slot in a frame after cell setup.

32. The equalizer of claim 27 wherein the TDD system is a Time Division-Synchronous Code Division Multiple Access system or a Time Division-Long Term Evolution system.

33. A Node B in a Time Division Duplex system, the Node B comprising:

a Radio Frequency (RF) filter supporting a frequency band;

an antenna calibration path that includes the RF filter;

an equalizer;

the equalizer configured to perform an equalization procedure comprising;

obtaining an amplitude and phase response of a calibration signal having a frequency in the frequency band by transmitting the calibration signal through the calibration path;

stepwise changing the frequency of the calibration signal by sweeping a Local Oscillator frequency on the calibration path by a predefined step until the amplitude and phase response of the calibration signal in the whole frequency band is obtained;

determining a transfer function of the RF filter based on the amplitude and phase response of the calibration signal in the whole frequency band;

equalizing the RF filter based on the determined transfer function of the RF filter.