WO2008102943A1 - Système et procédé de répétition pour l'annulation de signal d'interférence de réaction à fonction de distorsion préalable - Google Patents

Système et procédé de répétition pour l'annulation de signal d'interférence de réaction à fonction de distorsion préalable Download PDF

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Publication number
WO2008102943A1
WO2008102943A1 PCT/KR2007/005439 KR2007005439W WO2008102943A1 WO 2008102943 A1 WO2008102943 A1 WO 2008102943A1 KR 2007005439 W KR2007005439 W KR 2007005439W WO 2008102943 A1 WO2008102943 A1 WO 2008102943A1
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WIPO (PCT)
Prior art keywords
feedback
signal
residual error
coefficients
distorter
Prior art date
Application number
PCT/KR2007/005439
Other languages
English (en)
Inventor
Sung-Jun Baik
Joong-Han Choi
Original Assignee
Airpoint
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020070063887A external-priority patent/KR100879335B1/ko
Application filed by Airpoint filed Critical Airpoint
Priority to JP2009547159A priority Critical patent/JP4762348B2/ja
Priority to US12/523,457 priority patent/US8344800B2/en
Publication of WO2008102943A1 publication Critical patent/WO2008102943A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H04B7/15564—Relay station antennae loop interference reduction
    • H04B7/15585—Relay station antennae loop interference reduction by interference cancellation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/36—Modulator circuits; Transmitter circuits
    • H04L27/366—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator
    • H04L27/367—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion
    • H04L27/368—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion adaptive predistortion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference

Definitions

  • the present invention relates to a radio repeating system; and more particularly, to a radio repeating system and method with a pre-distortion function, which cancel a feedback interference signal by using an ICS (Interference Cancellation System) technique and linearize the characteristic of a PA (Power Amplifier) by using a pre- distortion technique, and a computer-readable recording medium that records a software program for realizing the method.
  • ICS Interference Cancellation System
  • PA Power Amplifier
  • a radio communication system employs a repeating system if normal services are not provided to terminals because a radio signal transmitted from a base station is weak due to a far distance from the base station, or obstacles such as topographical effects or construction structures, etc., or for service coverage expansion of the base station.
  • the repeating system typically includes a repeating apparatus having two antennas (a donor antenna and a service antenna) and a PA, wherein the donor antenna communicates signals with a base station and the service antenna communicates signals with terminals.
  • the repeating system is classified into an optical repeater, an RF repeater, a frequency changing repeater, a microwave repeater and the like depending on how to transmit a signal from a base station to a repeating apparatus.
  • the RF repeater is a most cost effective and simple method, it causes oscillations due to a phenomenon, in which a relay signal transmitted through the service antenna is feedbacked and applied to the donor antenna, and thus cannot be normally used.
  • FIG. 1 is a block diagram illustrating a bidirectional structure of a conventional RF repeating system.
  • a signal received through a donor antenna 100 is inputted to a filter and signal processor 120 or 160 contained in an RF repeating apparatus 130. Then, the filter and signal processor 120 or 160 removes undesired band components and the signal is amplified by a LNA (Low Noise Amplifier) 140 or 150 prepared at a next stage. The low noise amplified signal is then applied to a duplexer 170 or 110 which is an output amplifier, wherein the output amplifier again amplifies the signal and radiates it in the air through the service antenna 180 or donor antenna 100.
  • LNA Low Noise Amplifier
  • 10-2001-0050193 discloses a method for canceling a feedback interference signal by applying a signal processing technique to a received RF signal. Further, Korean Patent Application Nos. 10-2003-0034160 and 10-2005-0127580 improve both flexibility of signal processing and environment adaptation by processing a feedback interference signal using a digital signal processing technique for cancellation thereof in a manner that an RF signal is converted into a baseband signal to remove a feedback interference signal and back into an RF signal for its transmission.
  • an amplifier that amplifies a signal (relay signal) to be transmitted is provided with an LNA and a PA.
  • the main purpose of the LNA is to remove noises.
  • the PA largely amplifies an input signal to provide a high output, rather than removing noises, for high efficiency, but generates much heat.
  • the gain of the PA is defined as a ratio of the amplitude of an input signal to that of an output signal, and is not linearly varied with the amplitude of the input signal but becomes small when the output signal is near to a saturation region.
  • the difference between the input signal and the output signal of the PA is referred to as distortion.
  • distortion when different frequency signals are inputted as input signals, inter modulation occurs between the frequencies, thereby generating, in the output signal, mixed other frequency components that do not exist in the input signal. This is referred to as nonlinear distortion.
  • distortion caused by the amplitude of the signal is referred to as linear distortion.
  • the distortion generated by the PA is classified into an amplitude distortion where amplitude is distorted by the amplitude of the input signal and a phase distortion where phase is distorted by the phase thereof.
  • the nonlinear distortion is greatly generated at a saturation region point where the gain of the PA is maximized.
  • the simplest method for avoiding this is a method that makes the amplitude of the input signal small so that the PA operates enough below the saturation region.
  • the non-memory effect is that the output signal of the PA is determined depending on a current input signal only, while the memory (storage) effect refers to characteristic that causes distortion of the PA by nonlinear characteristic thereof by the amplitudes of a signal previously stored in a circuit and a current input signal.
  • the memory effect may be ignored in narrowband where the bandwidth of the input signal is smaller than that of the PA (output amplifier), but becomes very large by frequency differences of input signals in wideband like OFDM (Orthogonal Frequency Division Modulation).
  • the recent radio communication technology requires the efficient utility of spectrum in order to accommodate many subscribers and support a high communication speed, and thus uses wideband and multi-carrier and a combination of phase and amplitude modulations.
  • OFDM Orthogonal frequency division multiple access
  • bandwidth is wideband and it exhibits high PAPR (Peak to peak Average Power Ratio) characteristics. Due to this, there are large distortions of the PA by the memory effect and by wideband.
  • the distortion of the PA is varied with environments around the repeater, such as deterioration with the lapse of time, temperature, power, and frequency variations by temperature, which causes a large nonlinear phenomenon due to the distortion of the PA.
  • the PA needs to operate adaptively to various environments.
  • the compensation by such temperature employs a narrow thermal noise compensation technique that reflects temperature around the PA or ambient temperature by the level of input signal, not the narrow PA itself, and thus has the limitations in widespread thermal noise compensation, including ambient radio wave environments, processing gain, system limit, etc.
  • the PA is faithfully designed to have linear characteristic, it has the limitations that do not reflect processing limits such as quantization noise caused by the finite of LUT (Look-Up Table), modeling limit, and residual error caused by compromise between the hardware processing speed limit and complexity of implementation, or any error in variations of ambient environments.
  • ICS Interference Cancellation System
  • PA Power Amplifier
  • 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.
  • a PA Power Amplifier
  • a feedback ICS Interference Cancellation System
  • an operation method of a repeating system for cancellation of a feedback interference signal including 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.
  • a repeating system for cancellation of a feedback interference signal including: 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 non- linearity 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.
  • 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.
  • the present invention can cancel a feedback interference signal by using a feedback ICS technique and linearize the characteristics of a PA by using a pre-distortion technique.
  • the present invention primarily takes a pre-distortion through a closed loop consisting of an internal feedback circuit of a pre-distorter in order to linearize the PA, and then secondarily compensates for a widespread thermal noise that is not compensated for in the primary pre-distortion by extracting a residual error that remains in a feedback ICS by using a feedback interference signal received through an open loop consisting of a PA, a service antenna and a donor antenna, and transferring residual error information to the pre-distorter for secondary compensation, thereby removing a distortion caused by a comprehensive residual error that occurs in the PA.
  • the present invention cancels a feedback interference signal that is radiated through the service antenna of the repeating system and feedbacked to the donor antenna, and absorbs and processes a residual distortion that is not absorbed and processed in the pre-distorter.
  • the present invention enables the cancellation of the feedback interference signal adaptively to variations of radio wave environments around the repeating system, comprehensively reflects compensation for nonlinearity of the PA, thereby increasing the efficiency of the PA and also improving the flexibility of maintenance of the repeating system.
  • the conventional PA linearization modeling technique including a pre- distorter and a PA has the limitation that inevitably contains some degree of errors due to processing time, complexity of hardware or implementation, and the like, while the present invention collectively detects a widespread residual error occurred, which is not processed by the pre-distorter, at the feedback ICS, and provides residual error information to the control unit and the pre-distorter to update an LUT.
  • the present invention cancels the feedback interference and at the same time comprehensively compensates for the nonlinearity distortion of the PA, thereby preventing oscillations by feedback of the repeating system and increasing the efficiency of the PA to decrease heat generated by the PA.
  • the present invention can provide an economical repeating system, and improve maintenance and reliability thereof.
  • the present invention presents the acceptor unit in order to minimize the influence between functions and addition and combination of circuit components, and reflects in the repeating system a variety of factors such as the configuration of housing for radiation of heat having a large effect on the operation of the repeating system to outside, and a connection manner between the housing and the acceptors and their arrangement, the flexibility of maintenance of the repeating system, and arrangement to minimize electric effect between the acceptors, thereby making the maintenance of the repeating system easier, minimizing the electric effect between the acceptors, and efficiently radiating heat.
  • Fig. 1 is a block diagram illustrating a bidirectional structure of a conventional RF repeating system.
  • Fig. 2 is an overall block diagram illustrating a repeating system for cancellation of a feedback interference signal to which the present invention is applied.
  • Fig. 3 is a configuration diagram of a repeating system for cancellation of a feedback interference signal using a digital signal processing technique.
  • Fig. 4 is a diagram for explaining the configuration of a PA having a pre-distortion function in accordance with the present invention.
  • Fig. 5 is a block diagram illustrating the configuration of a repeating system for cancellation of a feedback interference signal having a pre-distortion function in accordance with the present invention.
  • Fig. 6 is a flowchart describing an operation method of a repeating system for cancellation of a feedback interference signal with a pre-distortion function in accordance with another embodiment of the present invention.
  • Fig. 7 is a detailed circuit diagram of the digital filter used in the present invention.
  • Fig. 8 is a block diagram showing an example of an algorithm of minimizing an error.
  • Fig. 9 is a diagram showing an analog circuit unit and a digital circuit unit of an acceptor.
  • Fig. 10 is a view showing one example of an acceptor arrangement state arranged on the board of housing in accordance with the invention.
  • FIG. 11 is a view showing the structure of disposing an amplifier acceptor on a housing cover to effectively radiate heat in accordance with the present invention. Best Mode for Carrying Out the Invention
  • a repeating system is divided into forward and backward depending on the direction of signal transfer.
  • the forward indicates the direction from a base station to a terminal, wherein a signal from the base station to the terminal is received by a donor antenna and transmitted to the terminal through a repeating procedure of the repeating system via a service antenna.
  • the backward indicates the direction from a terminal to a based station, wherein a signal from the terminal to the base station is received by a service antenna and transmitted to the base station through a repeating procedure of the repeating system via a donor antenna. Since the forward and backward as set forth above are the same in repeating procedure except for the signal transmission direction, the following operation principle will be described with respect to the forward only.
  • the present invention largely includes a feedback ICS for canceling a feedback interference signal and detecting a residual error, a pre-distorter for pre-distorting an input signal, and a control unit for controlling and interfacing the feedback ICS and the pre-distorter.
  • the pre-distorter primarily derives pre-distortion coefficients required for pre-distortion through an internal closed loop consisting of a coupler, a PA, an attenuator, a baseband converter, a training unit, a control unit, and an LUT, and stores them in the LUT.
  • An output of the PA resulting from the pre-distortion with the primarily derived pre-distortion coefficients does not have precise linearity due to quantization noise, modeling limit, implementation limit, and limitations such as ambient environments, to thus generate a residual error and transmit it to the service antenna.
  • the residual error so generated is feedbacked to an open loop consisting of the service antenna, the donor antenna, and the repeating system and inputted to the feedback ICS together with the feedback interference signal.
  • the feedback ICS detects the residual error that is not processed by the pre-distorter as well as canceling the feedback interference signal, and provides the corresponding information to the control unit.
  • the control unit controls the pre- distorter.
  • the pre-distorter secondarily calculates residual error coefficients on the basis of the residual error information and stores them in the LUT. By pre- distorting the input signal using this information, widespread thermal noises including quantization noise, adjacent channel interference, etc. can be removed.
  • the present invention primarily performs pre-distortion in a closed loop consisting of an internal feedback circuit of the pre-distorter to linearize the PA, detects a residual error in the feedback ICS by using a feedback interference signal received through an open loop consisting the PA, the service antenna, and the donor antenna through which widespread thermal noises that are not compensated in the primary pre-distortion is transmitted, and delivers the residual error information to the pre-distorter for secondary fine compensation. By dosing so, the distortion by a comprehensive residual error generated by the PA can be resolved.
  • Fig. 2 is an overall block diagram illustrating a repeating system for cancellation of a feedback interference signal to which the present invention is applied.
  • the repeating system of the invention further includes feedback ICSs 212 and 242 of a digital type for removing a feedback interference signal in the RF repeating system of Fig. 1.
  • a signal received through a donor antenna 200 is converted into a digital baseband signal by a baseband converter 210.
  • the baseband converter 210 is provided with a BPF (Band Pass Filter) 204 for passing only a signal of desired band, a down converter for down-converting the frequency of signal filtered by the BPF 204 into an intermediate frequency, and an ADC (Analog to Digital Converter) 208 for converting an analog signal down-converted into the intermediate frequency by the down converter 206 into a digital signal of baseband.
  • BPF Band Pass Filter
  • ADC Analog to Digital Converter
  • the digital baseband signal outputted from the baseband converter 210 is processed by the feedback ICS 212 to remove a feedback interference signal and then inputted to an RF converter 218.
  • the RF converter 218 converts the digital baseband signal, which the feedback interference signal is cancelled, into an RF signal and transmits it through a service antenna 230.
  • the RF converter 218 serves to perform the reverse function of the baseband converter 210, and is provided with a DAC (Digital to Analog Converter) 214 for converting the digital baseband signal from the feedback ICS 212 into an analog signal and an up converter 216 for up-converting the analog signal from the DAC 214 into an RF signal.
  • DAC Digital to Analog Converter
  • the RF signal from the up converter 216 is sufficiently power- amplified by a
  • PA 220 and sent to the service antenna 230 through a duplexer 232.
  • Fig. 3 illustrates a configuration diagram of a repeating system for cancellation of a feedback interference signal using a digital signal processing technique, wherein a baseband converter and an RF converter are identical to those shown in Fig. 2.
  • Sw is a signal which is received from a base station, amplified by a repeater, and is to be provided to a service antenna 310, i.e., a signal to be repeated
  • Si is a signal which is a feedback interference signal that is received again by a donor antenna 300 through a feedback channel after radiating through the service antenna 310, and has to be cancelled.
  • Sr is a signal which is received through the donor antenna 300, and having a desired relay signal and a undesired feedback interference signal exist at the same time.
  • the feedback interference signal Si is predicted by feedbacking a part of the signal amplified by the PA 308 through a coupler 312 at an output end where the signal is outputted to the service antenna 310, and applying it to a feedback signal processor 316 through a filter and baseband converter 314.
  • the feedback signal processor 316 generates a feedback interference prediction signal
  • FIG. 4 is a diagram for explaining the configuration of a PA with a pre-distortion function in accordance with the present invention.
  • the magnitude of a signal passing through the a baseband converter 400 is calculated by a magnitude calculator 402, pre-distorted by referring to an LUT 420, and then applied to an adder 404. Then, the adder 404 cancels the feedback interference signal by using the signal from the baseband converter 400 and the signal pre-distorted by referring to the LUT 420. Thereafter, a signal passing through the adder 404 is converted back into an RF signal by the RF converter 410 and outputted through the PA 430.
  • FIG. 5 is a block diagram illustrating the configuration of a repeating system for cancellation of a feedback interference signal having a pre-distortion function in accordance with the present invention, wherein a pre-distorter is incorporated in the repeating system.
  • the repeating system for cancellation of a feedback interference signal having a pre-distortion function in accordance with the invention includes a PA 524 for power- amplifying an output signal, a feedback ICS 530 for processing a feedback interference signal for cancellation thereof and detecting a residual error that remains after primary compensation in a pre-distorter 540 through an open loop to provide residual error information, the pre-distorter 540 for compensating for an error (e.g., narrow thermal noise) of the PA 524 by primary pre-distortion through an internal closed loop and secondarily fine-compensating for the residual error (which is widespread thermal noise that is not compensated in the primary pre-distortion) by using the information on residual error detected by the feedback ICS 530 to linearize the characteristic of the PA 524, and one control unit 516 for communicating control information (control data and control signals) between the feedback ICS 530 and the pre-distorter 540 and controlling the components.
  • an error e.g., narrow thermal noise
  • the residual error
  • control unit 516 organically controls the feedback ICS 530 and the pre-distorter
  • control unit 516 is implemented with one digital signal processing device for controlling the feedback ICS 530 and the pre-distorter 540.
  • the feedback ICS 530 detects a residual error generated by the technical limitations of operation environment or implementation of pre-distortion function through an open loop and provides corresponding residual error information to the pre- distorter 540 through the control unit 516, so that the pre-distorter 540 removes the residual error (which is the widespread thermal noise that is not compensated in the primary pre-distortion) by secondary fine compensation.
  • the feedback ICS 530 is provided with a baseband converter 500 for converting a received signal (including a relay signal and a feedback interference signal) into a baseband signal, an AGC (Automatic Gain Control) unit 508 for automatically adjusting the amplitude of an output signal of the relay signal to be relayed to control the entire gain of the repeating system, a channel estimator 506 for detecting (or estimating) feedback interference signal information (amplitude, phase, delay time, etc.) by using the baseband signal from the baseband converter 500 and the feedback signal from the AGC unit 508, and detects the residual error that remains after primary compensation by the pre-distorter 540 and delivers the residual error information to the control unit 516, an interference cancellation signal generator 504 for generating an interference cancellation signal to be used to cancel the feedback interference signal based on the feedback interference signal information detected by the channel estimator 506 and the feedback signal from the AGC unit 508, and an adder (feedback ICS) 502 for removing the feedback interference signal existing in the baseband signal
  • the control unit 516 controls related components so that they generate a reference signal when necessary or at regular intervals in order to compensate for the residual error or remove the feedback interference signal.
  • the reference signal to be generated is radiated through the PA 524 via the service antenna 310, wherein its phase and amplitude A are varied by passing through the channel and any delay ⁇ occurs therein.
  • the signal so varied and delayed is feedbacked and received by the donor antenna 300.
  • a received signal (including the feedback interference signal) passing through the donor antenna 300 is converted into a digital baseband signal through the baseband converter 500 and then fed to the channel estimator 506 and the adder 502. Then, at the channel estimator 506, an output signal (or a signal received from a first closed loop consisting of the coupler 526, the attenuator 528, and the baseband converter 500) for the AGC unit 508 and the baseband signal (including the feedback interference signal) from the baseband converter 500 are compared to measure an amplitude, a phase and a delay time. Then, feedback interference signal information is delivered to the interference cancellation signal generator 504, and a residual error that remains after primary compensation in the pre-distorter 540 is calculated to deliver the residual error information to the control unit 516.
  • the interference cancellation signal generator 504 generates an interference cancellation signal (inverse feedback interference signal) whose amplitude is equal to that of the feedback interference signal but phase is different from it by 180 degree by employing the feedback interference signal information such as amplitude, phase and delay time, and the feedback signal from the AGC unit 508.
  • the interference cancellation signal thus generated is then applied to the adder 502.
  • the adder 502 adds the baseband signal from the baseband converter 500 and the interference cancellation signal from the interference cancellation signal generator 504 to cancel the feedback interference signal that exists within the baseband signal from the baseband converter 500 and output a signal excluding the feedback interference signal to the AGC unit 508.
  • the signal received through the donor antenna 300 is inputted to the adder 502 through the baseband converter 500, the signal should be delayed by the time that is taken for the signal processing at the channel estimator 506 and the interference cancellation signal generator 504 at the front end of the adder 502, and then inputted to the adder 502.
  • the present invention directly feedbacks the signal at the output end of the AGC unit 508 and thus omits the process of converting the baseband signal into the RF signal and converting this back into the baseband signal, thereby reducing processing delay time and processing error.
  • the pre-distorter 540 of the invention is composed of a second closed loop including a look-up table (LUT) 514, combiners 510 and 512, an RF converter 520, a PA 524, a coupler 526, an attenuator 528, a baseband converter 522, a training unit 518, and a control unit 516.
  • LUT look-up table
  • the components excepting the PA 524 organically operate as below and perform the pre-distortion function of primarily compensating for an error (narrow thermal noise) of the PA 524.
  • the pre-distorter 540 includes the combiners 510 and 512 for combining pre-distortion coefficients or residual error coefficients stored in the LUT 514 and an output signal from the AGC unit 508, the RF converter 520 for converting a digital baseband signal from the combiners 510 and 512 into an RF signal to provide a converted signal to the PA 524, the coupler 526 for branching off and feedbacking part of the output signal of the PA 524, the attenuator 529 for attenuating a feedback signal branched off and feedbacked by the coupler 526, the baseband converter 522 for converting the RF signal attenuated by the attenuator 529 into a digital baseband signal, the training unit 518 for calculating pre-distortion coefficients by using an output signal of the baseband converter 522 and an output signal of the combiners 510 and 512, and calculating residual error coefficients based on the residual error information provided from the feedback interference signal canceller 530 through the
  • the training unit 518 primarily calculates pre-distortion coefficients by using a signal applied to the second closed loop in response to a training signal (e.g., a signal for initialization), and stores them in the LUT 514.
  • a training signal e.g., a signal for initialization
  • the control unit 516 stores them in the LUT 514.
  • a residual error occurs due to convergence limit of algorithm, LUT quantization noise and limit of processing means, ambient thermal noise of the PA, etc.
  • the residual error thus occurred is applied to an open loop consisting of the service antenna 310, the donor antenna 300, and the feedback ICS 530, so that the channel estimator 506 of the feedback ICS 530 detects the residual error and transfers residual error information to the control unit 516. Then, the control unit 516 instructs the training unit 518 to calculate residual error coefficients based on the residual error information, and thus can receive calculated residual error coefficients and store them in the LUT 514 or in a separate table (not shown).
  • FIG. 8 there is provided a block diagram representing an example of an algorithm of minimizing an error. That is, Fig. 8 shows an example of an algorithm of finding a value for minimizing e(n) indicative of an error of
  • the pre-distortion coefficients are primarily calculated in the second closed loop and the residual error coefficients are secondarily calculated by the open loop, to thus store each of them in the LUT 514 or the residual error coefficients in a separate table.
  • the repeating system operates in an adaptive mode, and derives the magnitude of the digital baseband signal (I, Q) outputted from the AGC unit 508 and searches its corresponding pre-distortion coefficients from the LUT 514.
  • the pre-distortion coefficients so searched and the output signal of the AGC unit 508 are multiplied by the first combiner 510 and added by the second combiner 512 for pre-distortion.
  • the result is sent to the service antenna 310 through the RF converter 520 and the PA 524.
  • the signal converted by the baseband converter 522 is trained by the training unit 518 to calculate a most optimal pre-distortion coefficient value, and the values stored in the LUT 514 are updated and the operation is continued in the adaptive mode.
  • the present invention is implemented by using the feedback
  • ICS 530 a correlator in the pre-distorter 540, and a digital filter shown in Fig. 7 in order to precisely detect (or estimate or calculate) the feedback interference signal and the residual error, thereby calculating precise feedback interference cancellation coefficients (e.g., feedback interference signal information such as amplitude, phase, delay time, etc.), pre-distortion coefficients and residual error coefficients, and applying them for updating.
  • precise feedback interference cancellation coefficients e.g., feedback interference signal information such as amplitude, phase, delay time, etc.
  • the conventional PA linearization modeling technique including the pre- distorter and the PA has the limitation that has some degree of errors due to processing time, complexity of hardware or implementation, and the like.
  • the feedback ICS 530 detects at a time a widespread residual error occurred, which is not processed by the pre-distorter 540, and provides residual error information to the control unit 516 and the pre-distorter 540 to update the LUT 514.
  • the feedback interference is cancelled and non-linear distortion of the PA is compensated for, which prevent oscillations by feedback of the RF repeater and improve the efficiency of the PA to reduce heat generated by the PA.
  • FIG. 6 is a flowchart illustrating an operation method of a repeating system for cancellation of a feedback interference signal with a pre-distortion function in accordance with another embodiment of the present invention.
  • the process of the invention stops the operation of the pre-distorter 540 and initializes the feedback ICS 530, and then operates the feedback ICS 530 in normal mode to continuously update feedback interference cancellation coefficients in steps S601 and S603.
  • the process stops the function of the pre-distorter 540 and performs initialization of the feedback ICS 530 in step S601. More concretely, the process stops the function of the pre-distorter 540, and calculates feedback interference cancellation coefficients required for cancellation of feedback interference for its initialization.
  • step S601 If the initialization has been finished in step S601, the process cancels the feedback interference signal while normally operating the feedback ICS 530 by using the calculated feedback interference cancellation coefficients, and normally operates the feedback ICS 530 while continuously updating the feedback interference cancellation coefficients in step S 603.
  • the process initializes the closed loop of the pre-distorter 540 to primarily derive pre-distortion coefficients and initializes the open loop while applying the pre- distortion based on the primary pre-distortion coefficients to obtain residual error information in steps S605 and S607.
  • the process initializes the pre-distorter 540, primarily calculates the pre-distortion coefficients through the closed loop by using training vector data of the pre-distorter 540, and stores them in the LUT 514. And then, the process operates the pre-distorter 540 by using the pre-distortion coefficients stored in the LUT 514 and applies the pre- distortion thereto to continuously update the pre-distortion coefficients stored in the LUT 514 while compensating for narrow thermal noise in step S605.
  • the process outputs the signal pre-distorted by the primarily calculated and updated pre-distortion coefficients through the PA 524 and initializes the open loop, so that the feedback ICS 530 can detect the residual error, and then the control unit 516 accepts the detected residual error in step S607.
  • the process converts the pre-distorter 540 into normal mode and updates the pre-distortion coefficients and the residual error in step 609.
  • the process secondarily calculates residual error coefficients by using the accepted residual error information and stores them in the LUT 514. Then, it converts the pre-distorter 540 into normal mode, performs the pre-distortion function, at the same time continues to calculate the pre-distortion coefficients and the residual error, and continues to update the values of the LUT 514 in step S609.
  • the feedback ICS 530 and the pre-distorter 540 operate in normal mode, thereby continuously updating the feedback interference cancellation coefficients, the pre-distortion coefficients, and the residual error coefficients adaptively to operation environments in step 611.
  • Fig. 9 is a diagram showing an analog circuit unit and a digital circuit unit of an acceptor.
  • the analog circuit unit including at least two of a duplexer, a
  • BPF an LNA, a down converter, an ADC, an AGC unit, a DAC, an up converter, a PA, and an attenuator is arranged in at least one first printed board; and the digital circuit unit including at least one of a feedback ICS, a pre-distorter, and a control unit is arranged in at least one second printed board.
  • a housing is divided into a plurality of acceptors by using a conductive accepting surface (that performs a radiant heat plate function) for radiating heat generated from the digital circuit unit and the analog circuit unit, and the digital circuit unit and the analog circuit unit are accepted in one acceptor for easy heat radiation from the conductive accepting surface.
  • the acceptor is configured in a polyhedron made of a conductive metal material and the inner part of the polyhedron is separately divided into more than two spaces by the conductive metal plate, one of the divided spaces accepting the analog circuit unit and the other one space freely accepting the digital circuit.
  • heat is radiated through at least one contact surface between the divided spaces.
  • the acceptors are separately arranged 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.
  • the acceptors are disposed on the housing formed of the polyhedron made of a conductive member having a high conductivity, and one surface of the lower end, one or more surfaces or the cover of the housing is implemented with a conductive substrate with good thermal conduction for easy heat radiation, and the conductive accepting surface (that performs a radiant heat plate function) is attached to the rear surface of the conductive substrate, namely, at least one conductive accepting surface of the acceptor is in contact with the conductive substrate of the housing for heat radiation.
  • a first analog circuit unit including at least two components of a duplexer, a BPF, an LNA, a down converter, an ADC, an AGC unit, a DAC, an up converter, a PA, and an attenuator is arranged in at least one first printed board; and a first digital circuit unit including at least one of a feedback ICS, a pre-distorter, and a control unit is arranged in at least one second printed board.
  • a second analog circuit unit and a second digital circuit unit are also provided in the same configuration except that the signal direction is reverse.
  • the forward/backward acceptors are composed of the analog circuit unit and the digital circuit unit.
  • the digital circuit unit is connected by many lines because it is composed in the form of bus between the devices therein. Therefore, it is preferable to shorten the wiring and at the same time arrange the digital circuit unit separately from the analog circuit unit in order to minimize the effect of infinite harmonic signal generated by transiting from 1 to 0, and vice versa.
  • the analog circuit unit is connected by one line and gets much electric effect by its peripheral circuit devices or by connection lines, it is preferably implemented on a separate substrate from the digital circuit unit. Further, it is preferable that each substrate is accepted freely in one acceptor but separated therefrom.
  • the forward/backward acceptors make a polyhedron (e.g., hexahedron) with a conductive metal material, and the inner part of the polyhedron is separately divided into two space layers where the analog circuit unit and the digital circuit unit are accepted in each layer, the layers being separated by a conductive metal plate serving as a radiant heat plate.
  • a polyhedron e.g., hexahedron
  • the inner part of the polyhedron is separately divided into two space layers where the analog circuit unit and the digital circuit unit are accepted in each layer, the layers being separated by a conductive metal plate serving as a radiant heat plate.
  • the duplexer is composed of a plurality of analog devices in order to sharpen frequency cut-off characteristics, and is therefore preferable to be accepted in a separate acceptor from other components in order to isolate from an internal electric effect of the system. Since the amplifier generates much heat, it is also preferable to be accepted in a separate acceptor in order to effectively radiate heat.
  • Fig. 10 is a view showing one example of an acceptor arrangement state disposed on the board of housing in accordance with the invention.
  • the duplexer acceptor that is insensitive to heat is disposed at the upper end of the amplifier acceptor.
  • a remote controller acceptor is disposed at the upper end of a power supplier acceptor. That is, at least some of the acceptors may be laminately disposed.
  • At least two of a forward function unit acceptor, a backward function unit acceptor, a power supplier acceptor, a duplexer acceptor, an amplifier acceptor, and a remoter controller acceptor may be laminately disposed.
  • FIG. 11 is a view showing the structure of disposing an amplifier acceptor in a housing cover to effectively radiate heat in accordance with the present invention, especially an example where an amplifier acceptor is disposed in a housing cover to effectively radiate heat in order to secure a wide space of the housing main body and for a housing board and a wide space of each acceptor to be in contact with the housing.
  • At least one surface of the inside of the housing or housing cover of the repeating system is implemented with a conductive substrate with thermal conduction, a radiant heat plate is attached to the rear surface of the conductive substrate, and part of the polyhedral acceptor is in contact with the board of the housing for heat radiation.
  • At least one surface of the lower end of the inside of the repeating system housing or the inside of the housing switch (cover) is implemented with a conductive substrate having a good thermal conduction, a radiant heat plate is attached to the rear surface of the conductive substrate, and at least two polyhedral acceptors of the forward function unit acceptor, the backward function acceptor, the power supplier acceptor, the duplexer acceptor, the amplifier acceptor, and the remote controller acceptor are in contact with the conductive substrate for heat radiation.
  • the method of the present invention as mentioned above may be implemented by a software program that is stored in a computer-readable storage medium such as CD- ROM, RAM, ROM, floppy disk, hard disk, optical magnetic disk, or the like. This procedure may be readily carried out by those skilled in the art; and therefore, details of thereof are omitted here.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)

Abstract

La présente invention concerne un système de répétition pour l'annulation de signal d'interférence, comportant : un amplificateur de puissance permettant l'amplification de la puissance d'un signal de sortie; un système d'annulation d'interférence de réaction pour annuler un signal d'interférence de réaction et détecter une erreur résiduelle; un générateur de distorsion préalable pour compenser une erreur de l'amplificateur de puissance par l'application de distorsion préalable et pour compenser l'erreur résiduelle au moyen d'une information concernant l'erreur résiduelle détectée par le système d'annulation d'interférence de réaction pour linéariser la caractéristique de l'amplificateur de puissance; et une unité de commande pour commander le système d'annulation d'interférence de réaction et le générateur de distorsion préalable.
PCT/KR2007/005439 2007-02-23 2007-10-31 Système et procédé de répétition pour l'annulation de signal d'interférence de réaction à fonction de distorsion préalable WO2008102943A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2009547159A JP4762348B2 (ja) 2007-02-23 2007-10-31 前置歪曲機能を備えた帰還干渉信号除去中継システムおよびその方法
US12/523,457 US8344800B2 (en) 2007-02-23 2007-10-31 Repeating system and method for cancellation of feedback interference signal with pre-distortion function

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2007-0018530 2007-02-23
KR20070018530 2007-02-23
KR10-2007-0063887 2007-06-27
KR1020070063887A KR100879335B1 (ko) 2007-02-23 2007-06-27 전치 왜곡 기능을 구비한 귀환간섭신호 제거 중계 시스템및 그 방법

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WO2008102943A1 true WO2008102943A1 (fr) 2008-08-28

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WO2011097844A1 (fr) * 2010-02-09 2011-08-18 中兴通讯股份有限公司 Procédé et appareil de réduction de la surcompensation de distorsion de liaison d'un système de prédistorsion numérique
EP3145144A4 (fr) * 2014-08-01 2017-06-21 Huawei Technologies Co. Ltd. Émetteur et procédé d'élimination de brouillage

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KR20010090039A (ko) * 2001-08-21 2001-10-18 박상열 궤환기법을 응용한 실시간 자력적/적응성 간섭잡음제거장치 및 그 방법
US20040017257A1 (en) * 2002-07-20 2004-01-29 Lg Electronics Inc. Apparatus and method for compensating pre-distortion of a power amplifier
US20040179629A1 (en) * 2002-12-24 2004-09-16 Yoo-Seung Song Digital predistorter for a wideband power amplifier and adaptation method
KR20060072077A (ko) * 2004-12-22 2006-06-27 에스케이 텔레콤주식회사 이동통신 시스템을 위한 무선중계 장치 및 중계 방법

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US20040017257A1 (en) * 2002-07-20 2004-01-29 Lg Electronics Inc. Apparatus and method for compensating pre-distortion of a power amplifier
US20040179629A1 (en) * 2002-12-24 2004-09-16 Yoo-Seung Song Digital predistorter for a wideband power amplifier and adaptation method
KR20060072077A (ko) * 2004-12-22 2006-06-27 에스케이 텔레콤주식회사 이동통신 시스템을 위한 무선중계 장치 및 중계 방법

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Publication number Priority date Publication date Assignee Title
WO2011097844A1 (fr) * 2010-02-09 2011-08-18 中兴通讯股份有限公司 Procédé et appareil de réduction de la surcompensation de distorsion de liaison d'un système de prédistorsion numérique
EP3145144A4 (fr) * 2014-08-01 2017-06-21 Huawei Technologies Co. Ltd. Émetteur et procédé d'élimination de brouillage
US9794090B2 (en) 2014-08-01 2017-10-17 Huawei Technologies Co., Ltd. Transmitter and interference cancellation method

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