REPEATING SYSTEM AND METHOD FOR CANCELLATION OF FEEDBACK INTERFERENCE SIGNAL WITH PRE-DISTORTION FUNCTION

• US 20100109771A1
• Filed: 10/31/2007
• Published: 05/06/2010
• Est. Priority Date: 02/23/2007
• Status: Active Grant

• Current Assignee: Fujitsu Network Solutions Limited (Fujitsu Limited)
• Original Assignee: Hynix Semiconductor Incorporated (SK Hynix Inc.)
• Inventors: Baik, Sung-Jun, Choi, Joong-Han
• Granted Patent: US 8,344,800 B2
• Time in Patent Office: Days
• US Class Current: 330/149
• CPC Class Codes: H04B 7/15585 by interference cancellation

Abstract

There is provided a repeating system for cancellation of a feedback interference signal, including: a PA (Power Amplifier) for power-amplifying an output signal; a feedback ICS (Interference Cancellation System) for canceling a feedback interference signal and detecting a residual error; a pre-distorter for compensating for an error of the PA by applying pre-distortion and compensating for the residual error by using information on the residual error detected by the feedback ICS to linearize the characteristic of the PA; and a control unit for controlling the feedback ICS and the pre-distorter.

Claims

1. A repeating system for cancellation of a feedback interference signal, comprising:

a PA (Power Amplifier) for power-amplifying an output signal;

a feedback ICS (Interference Cancellation System) for canceling a feedback interference signal and detecting a residual error;

a pre-distorter for compensating for an error of the PA by applying pre-distortion and compensating for the residual error by using information on the residual error detected by the feedback ICS to linearize the characteristic of the PA; and

a control unit for controlling the feedback ICS and the pre-distorter.

2. The repeating system of claim 1, wherein the pre-distorter primarily compensates for a non-linear characteristic of the PA by applying pre-distortion through an internal closed loop and secondarily compensates for the residual error which is not compensated by the primary pre-distortion by using the information on the residual error detected by the feedback ICS to linearize the characteristic of the PA.

3. The repeating system of claim 2, wherein the feedback ICS processes a feedback interference signal for cancellation thereof and detects a residual error that remains after primary compensation by the pre-distorter through an open loop, and provides residual error information to the pre-distorter through the control unit as control information.

4. The repeating system of claim 1, wherein the control unit is implemented with one controller which communicates control information (control data and control signals) between the feedback ICS and the pre-distorter, and controls the two devices.

5. The repeating system of claim 1, wherein the pre-distorter includes:

an RF converter for converting a signal from a combiner into an RF signal to provide a converted signal to the PA;

a coupling means for branching off and feedbacking part of the output signal of the PA;

an attenuator for attenuating a feedback signal which is branched off and feedbacked by the coupling means;

a first baseband converter for converting the RF signal attenuated by the attenuator into a baseband signal;

a training unit for calculating pre-distortion coefficients by using an output signal of the first baseband converter and an output signal of the combiner, and calculating residual error coefficients based on the residual error information provided from the feedback ICS through the control unit;

a storing means for storing the pre-distortion coefficients and the residual error coefficients calculated by the training unit; and

the combiner for combining the pre-distortion coefficients or the residual error coefficients stored in the storing means and an output signal from an AGC (Automatic Gain Control) unit of the feedback ICS.

6. The repeating system of claim 5, wherein the training unit primarily calculates the pre-distortion coefficients by using a signal passing through the internal closed loop upon receipt of a training signal (which is a signal for initialization), and stores the same in the storing means through the control unit;

and

secondarily calculates the residual error coefficients so that the residual error is minimized by reception of the residual error information detected by the feedback ICS through the control unit, and stores the same in the storing means through the control unit.

7. The repeating system of claim 5, wherein the combiner multiplies, in a first combiner, the coefficients searched from the storing means depending on the magnitude of the output signal from the AGC unit by the output signal from the AGC unit, and adds the multiplication result for pre-distortion in a second combiner.

8. The repeating system of claim 5, wherein the feedback ICS includes:

a second baseband converter for converting a received signal (having a relay signal or feedback interference signal) into a baseband signal;

the AGC unit for automatically adjusting the magnitude of an output signal of a relay signal to be relayed;

a channel estimator for detecting (or estimating) feedback interference signal information by using the baseband signal from the second baseband converter and the feedback signal from the AGC unit, and detects the residual error that remains after primary compensation by the pre-distorter and delivers residual error information to the control unit;

an interference cancellation signal generator for generating an interference cancellation signal based on the feedback interference signal information detected by the channel estimator and the feedback signal from the AGC unit; and

a feedback interference signal cancellator for canceling the feedback interference signal existing in the baseband signal from the baseband converter by using the interference cancellation signal from the interference cancellation signal generator, and delivers it to the AGC unit.

9. The repeating system of claim 1, wherein an analog circuit unit is disposed on at least one first printed board,

a digital circuit unit is disposed on at least one second printed board, and

a housing is divided into a plurality of acceptors by using a conductive accepting surface for radiating heat generated from the digital circuit unit and the analog circuit unit,

the digital circuit unit and the analog circuit unit being accepted in one of the acceptors for easy heat radiation in the conductive accepting surface.

10. The repeating system of claim 9, wherein each of the acceptors is configured in a polyhedron made of a conductive metal material and the inner part of polyhedral acceptor is separately divided into more than two spaces by a conductive metal plate, one of the divided spaces accepting the analog circuit unit and the other one space accepting the digital circuit unit, and heat is radiated by the conductive metal plate.

11. The repeating system of claim 10, wherein each of the acceptors is disposed in the housing formed of polyhedron of a conductive member having a high conductivity, and one surface of the lower end, one or more surface or the cover of the housing is implemented with a conductive substrate with good thermal conduction for easy heat radiation, and at least one conductive accepting surface of each of the acceptors is in contact with the conductive substrate of the housing for heat radiation.

12. The repeating system of claim 11, wherein the acceptors are separately disposed on the board of the housing depending on the size, scale, and radiant heat efficiency of the repeating system for cancellation of a feedback interference signal.

13. The repeating system of claim 11, wherein the housing accepts a duplexer consisting of a plurality of analog devices to sharpen frequency cut-off characteristics in a separate acceptor from other components to isolate it from electric effect of the inside of the system, and accepts the amplifier in another separate acceptor to effectively radiate heat from the amplifier generating much heat.

14. The repeating system of claim 10, wherein if a sufficient space is not secured, each of the acceptors laminately disposes components that are not sensitive to heat on the top of any acceptor that accepts other components.

15. An operation method of a repeating system for cancellation of a feedback interference signal, comprising the steps of:

a) stopping the operation of a pre-distorter, initializing a feedback ICS, and operating the feedback ICS in normal mode to continuously update feedback interference cancellation coefficients;

b) initializing a closed loop of the pre-distorter and primarily calculating pre-distortion coefficients, and initializing an open loop while applying pre-distortion by using the calculated pre-distortion coefficients to acquire residual error information; and

c) converting the pre-distorter into normal mode to update the pre-distortion coefficients and the residual error coefficients.

16. The operation method of a repeating system of claim 15, further comprising the step of:

d) continuously updating the feedback interference cancellation coefficients, pre-distortion coefficients, and residual error coefficients adaptively to environments while the feedback ICS and the pre-distorter operate in normal operation.

17. The repeating method of claim 15, wherein the step a) includes the steps of:

a1) stopping the functions of the pre-distorter;

a2) calculating the feedback interference cancellation coefficients required for cancellation of the feedback interference signal and performing the initialization of the feedback ICS; and

a3) canceling the feedback interference signal while normally operating the feedback ICS by using the calculated feedback interference cancellation coefficients, and normally operating the feedback ICS while continuously updating the interference cancellation coefficients.

18. The repeating method of claim 15, wherein the step b) includes the steps of:

b1) initializing the pre-distorter;

b2) primarily calculating the pre-distortion coefficients through the closed loop by using training vector data of the pre-distorter and storing the calculated pre-distortion coefficients in an LUP (Look-Up Table);

b3) operating the pre-distorter by using the pre-distortion coefficients stored in the LUS and continuously updating the pre-distortion coefficients in the LUS while compensating for nonlinearity by applying pre-distortion; and

b4) outputting a signal pre-distorted by the primarily calculated and updated pre-distortion coefficients through a PA, and initiating the open loop and detecting the residual error from the feedback ICS to derive the residual error information.

19. The repeating method of claim 18, wherein the step c) includes the steps of:

c1) secondarily calculating residual error coefficients by using the derived residual error information and storing them in the LUT; and

c2) converting the pre-distorter into normal operation mode and continuously calculating pre-distortion coefficients and residual error coefficients along with execution of pre-distortion function, to continuously update the values of the LUT.

20. A repeating system for cancellation of a feedback interference signal, comprising:

a PA for power-amplifying an output signal;

a feedback ICS for canceling a feedback interference signal existing in a relay signal;

a pre-distorter for compensating for nonlinearity of the PA by using pre-distortion to linearize the characteristic of the PA; and

a control unit for controlling the feedback ICS and the pre-distorter.

21. The repeating system of claim 20, wherein the control unit is implemented with one digital signal processor for controlling the feedback ICS and the pre-distorter.

22. A housing for accepting circuits with which an analog circuit unit and a digital circuit unit are linked,

wherein the analog circuit unit is disposed on at least one first printed board,

the digital circuit unit is disposed on at least one second printed board, and

the housing is divided into a plurality of acceptors by using a conductive accepting surface for radiating heat generated from the digital circuit unit and the analog circuit unit,

the digital circuit unit and the analog circuit unit being accepted in one of the acceptors for easy heat radiation in the conductive accepting surface.

23. The housing of claim 22, wherein each of the acceptors is configured in a polyhedron made of a conductive metal material and the inner part of polyhedral acceptor is separately divided into more than two spaces by a conductive metal plate, one of the divided spaces accepting the analog circuit unit and the other one space accepting the digital circuit unit, and heat is radiated by the conductive metal plate.

24. The housing of claim 22, wherein each of the acceptors is disposed in the housing formed of polyhedron of a conductive member having a high conductivity, and one surface of the lower end, one or more surface or the cover of the housing is implemented with a conductive substrate with good thermal conduction for easy heat radiation, and at least one conductive accepting surface of each of the acceptors is in contact with the conductive substrate of the housing for heat radiation.

25. The housing of claim 24, wherein if a sufficient space is not secured, each of the acceptors laminately disposes components that are not sensitive to heat in the top of any acceptor that accepts other components.

26. A computer-readable recording medium that records a software program of implementing an operation method of a repeating system having a processor for cancellation of a feedback interference signal, comprising the functions of:

stopping the operation of a pre-distorter, initializing a feedback ICS, and operating the feedback ICS in normal mode to continuously update feedback interference cancellation coefficients;

initializing a closed loop of the pre-distorter and primarily calculating pre-distortion coefficients, and initializing an open loop while applying the pre-distortion by using the calculated pre-distortion coefficients to acquire residual error information; and

converting the pre-distorter into normal mode and updating the pre-distortion coefficients and residual error coefficients.

27. The computer-readable storage medium of claim 26, further comprising the function of:

continuously updating the feedback interference cancellation coefficients, pre-distortion coefficients, and residual error coefficients adaptively to environments while the feedback ICS and the pre-distorter operate in the normal operation.