WO2009082084A1 - Method and apparatus for removing intermodulation generated at passive devices - Google Patents

Method and apparatus for removing intermodulation generated at passive devices Download PDF

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Publication number
WO2009082084A1
WO2009082084A1 PCT/KR2008/005713 KR2008005713W WO2009082084A1 WO 2009082084 A1 WO2009082084 A1 WO 2009082084A1 KR 2008005713 W KR2008005713 W KR 2008005713W WO 2009082084 A1 WO2009082084 A1 WO 2009082084A1
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WIPO (PCT)
Prior art keywords
signal
intermodulation
estimated
intermodulation signal
nonlinear
Prior art date
Application number
PCT/KR2008/005713
Other languages
French (fr)
Inventor
Yong Sik Shin
Se Hyun Oh
Jong Tae Ihm
Jong Guk Ahn
Byung Suk Lee
Kyoung Joon Kim
Sung Hoon Jeon
Hyun Mo Ko
Jin Yul Kim
Peter Choi
Sun Ik Lee
Original Assignee
Sk Telecom Co., Ltd.
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.)
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Publication date
Priority claimed from KR1020070137639A external-priority patent/KR101421541B1/en
Priority claimed from KR1020070138656A external-priority patent/KR101172293B1/en
Application filed by Sk Telecom Co., Ltd. filed Critical Sk Telecom Co., Ltd.
Publication of WO2009082084A1 publication Critical patent/WO2009082084A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/12—Neutralising, balancing, or compensation arrangements
    • H04B1/123—Neutralising, balancing, or compensation arrangements using adaptive balancing or compensation means

Definitions

  • the present invention relates, in general, to a method and apparatus for removing an intermodulation signal generated in at least one passive device, and, more particularly, to a method and apparatus for removing an intermodulation signal generated in at least one passive device, which effectively removes a complex nonlinear intermodulation signal, which is generated in at least one passive device within a communication apparatus using various frequencies and which distorts one or more signals, and removes effect attributable to the intermodulation signal, prevents the distortion of the signals, and improves signal detection performance, thereby improving communication service quality.
  • Mobile communication services have been continuously varied, and the number of subscribers has increased. According to this trend, mobile communication service providers have obtained multiband frequencies for providing their services. That is, various frequencies have been used in order to provide service by obtaining a plurality of frequency bands in the same mobile communication method, or in order to provide service based on each of mobile communication methods by constituting a communication network such that the plurality of mobile communication methods are mixed.
  • an object of the present invention is to effectively remove an intermodulation signal generated in at least one passive device within a communication apparatus using various frequencies, to prevent the distortion of signals, and to improve signal detection performance, thereby improving communication service quality.
  • Another object of the present invention is to remove effect attributable to an intermodulation signal generated in at least one passive device provided in a communication apparatus, thereby improving service quality.
  • a further object of the present invention is to adjust an (estimated) intermodulation signal, which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, through control for input/output characteristics and nonlinear characteristics, so that the estimated intermodulation signal, having high correlation with the intermodulation signal to be removed, is generated, thereby improving intermodulation signal removal performance.
  • the present invention provides a device for removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the device including M virtual intermodulation signal generation units each for receiving a first signal and a second signal, and generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit for receiving the virtual intermodulation signals, generating K nonlinear signals for each of the virtual intermodulation signals, generating an estimated intermodulation signal by combining the generated nonlinear signals, and, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
  • the present invention provides a method of removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the method including a virtual intermodulation signal generation step (a) of receiving a first signal and a second signal, and generating M virtual intermodulation signals; a nonlinear signal generation step (b) of generating K nonlinear signals for each of the virtual intermodulation signals; an intermodulation signal estimation step (c) of generating an estimated intermodulation signal by combining the nonlinear signals using a preset filter coefficient; and an intermodulation signal cancellation step (d) of, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
  • the present invention provides a device for removing an intermodulation signal in order to remove an intermodulation signal generated in at least one passive device, the device including an estimated intermodulation signal generation unit for receiving a first signal containing a first frequency component and a second signal containing a second frequency component, generating an estimated intermodulation signal containing a third frequency component, controlling nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and a correlation filter unit for receiving a signal (A) including an intermodulation signal and the output estimated intermodulation signal, extracting correlation between the signal (A) and the estimated intermodulation signal, and then removing the intermodulation signal included in the signal (A).
  • an estimated intermodulation signal generation unit for receiving a first signal containing a first frequency component and a second signal containing a second frequency component, generating an estimated intermodulation signal containing a third frequency component, controlling nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated inter
  • the present invention provides a method of removing an intermodulation signal generated in at least one passive device, the method including an input signal reception step (a) of receiving a first signal containing a first frequency component and a second signal containing a second frequency component; an estimated intermodulation signal generation step (b) of generating an estimated intermodulation signal containing a third frequency component based on the received first signal and the second signal, controlling nonlinear characteristics of the generated estimated intermodulation signal, and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and an intermodulation signal cancellation step (c) of receiving a signal (A), which includes an intermodulation signal, and the estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, extracting correlation between the signal (A) and the estimated intermodulation signal, and removing the intermodulation signal included in the signal (A).
  • an intermodulation signal generated in at least one passive device within a communication apparatus using various frequencies is effectively removed, the distortion of signals is prevented, and signal detection performance is improved, so that there is an advantage of improving communication service quality.
  • effect attributable to an intermodulation signal generated in at least one passive device provided in a communication apparatus is removed, so that there is an advantage of improving service quality.
  • an (estimated) intermodulation signal which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that the estimated intermodulation signal, having high correlation with the intermodulation signal to be removed, can be generated, so that there is an advantage of improving intermodulation signal removal performance.
  • FIG. 1 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention
  • FIG. 2 is a detailed view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention
  • FIG. 3 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention
  • FIG. 4 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention. [19] FIG.
  • FIG. 5 is a view showing an estimated intermodulation signal generation unit for generating an estimated intermodulation signal by controlling input characteristics, nonlinear characteristics, and output characteristics;
  • FIG. 6 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
  • FIG. 7 is a detailed flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
  • FIG. 1 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention.
  • the above-mentioned "intermodulation signal generated in at least one passive device” means an intermodulation signal which is generated in at least one passive device provided in a communication apparatus, and corresponds to a signal which causes noise to be generated in an adjacent frequency band and reduces a signal-to-noise ratio, that is, a signal desired to be removed in the present invention.
  • the "intermodulation signal generated in at least one passive device” is simply referred to as an "intermodulation signal”.
  • a device 100 for removing an intermodulation signal generated in at least one passive device according to the present invention in order to remove an intermodulation signal generated in at least one passive device provided in a communication apparatus includes M virtual intermodulation signal generation units 110 each for receiving a first signal 10 and a second signal 20, and then generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit 120 for receiving the virtual intermodulation signals, generating K nonlinear signals for each of the virtual intermodulation signals, combining the generated nonlinear signals and then generating an estimated intermodulation signal, and removing an intermodulation signal from a fourth signal 30 using the generated estimated intermodulation signal when the fourth signal, including a third signal and the intermodulation signal, is input.
  • Each of the virtual intermodulation signal generation units 110 receives the first signal 10 containing a first frequency component f 1 and the second signal 20 containing a second frequency component f2, and then generates a virtual inter- modulation signal containing frequency components in which sums of and subtractions between harmonic frequencies of the first and second signals are combined together.
  • the virtual intermodulation signals may include signals containing frequency components 2f l-f2 and 2f2-f 1.
  • the virtual intermodulation signal generation unit 110 may include one or more active devices and/or passive devices.
  • the passive intermodulation cancellation management unit 120 may include a signal order changing unit for generating predetermined order nonlinear signals based on each of the virtual intermodulation signals which are output and received from the virtual intermodulation signal generation unit 110. If, K nonlinear signals are generated with respect to a single virtual intermodulation signal received from the single virtual intermodulation signal generation unit 110, the signal order changing unit generates nonlinear signals from a first order nonlinear signal to a K-th order nonlinear signal.
  • 'K' is a positive integer. Therefore, the K nonlinear signals, generated by the passive intermodulation cancellation management unit 120, include signals ranging from the first order nonlinear signal to the K-th order nonlinear signal.
  • the passive intermodulation cancellation management unit 120 controls (adjusts) and sets a filter coefficient, and combines M x K nonlinear signals and then generates an estimated intermodulation signal which is similar to an intermodulation signal desired to be removed.
  • the passive intermodulation cancellation management unit 120 includes a combination unit for performing the function. A method of the combination unit of the passive intermodulation cancellation management unit 120 setting a filter coefficient in order to generate a similar estimated intermodulation signal can be performed using various algorithms.
  • the passive intermodulation cancellation management unit 120 includes a cancellation unit for receiving the estimated intermodulation signal and the fourth signal 30, and then removing the intermodulation signal included in the fourth signal 30.
  • the cancellation unit for performing an intermodulation signal removal function removes the intermodulation signal by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal, from the fourth signal 30, including the third signal desired to be received and the intermodulation signal which distorts the third signal and then reduces a detection performance.
  • the 'M' indicating the number of the above-described virtual intermodulation signal generation units 110 and the 'K' indicating the order of nonlinear signals are adjusted and set based on the result of the detection performance of the third signal.
  • a device for removing an intermodulation signal generated in at least one passive device, having a different configuration can be implemented.
  • Each of the above-described virtual intermodulation signal generation units 110 may include various devices, such as passive devices and/or active devices, which can generate virtual intermodulation signals.
  • the device 100 for removing an intermodulation signal generated in at least one passive device includes a plurality of virtual intermodulation signal generation units 110 and a passive intermodulation cancellation management unit 120 for performing a function of changing the orders of signals and combining the signals with each other. Therefore, the device 100 for removing an intermodulation signal generated in at least one passive device generates a plurality of (M) virtual intermodulation signals, changes each of the virtual intermodulation signals into various orders nonlinear signals and then combines them with each other, and generates an estimated intermodulation signal, which is similar to an intermodulation signal desired to be removed. Therefore, the device 100 for removing an intermodulation signal can remove an intermodulation signal having nonlinear characteristics which may occur in complicated and various manners. Accordingly, signal detection performance is improved for a communication apparatus, such as a repeater or a base station, including a device for removing an intermodulation signal, thereby providing communication service to users with great satisfaction.
  • a communication apparatus such as a repeater or a base station
  • FIG. 2 is a detailed view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention.
  • a device 100 for removing an intermodulation signal generated in at least one passive device includes M virtual intermodulation signal generation units each for receiving a first signal and a second signal and then generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit 120 for generating an estimated intermodulation signal, and removing an intermodulation signal using the generated estimated intermodulation signal.
  • the passive intermodulation cancellation management unit 120 includes a signal order changing unit 121 for receiving virtual intermodulation signals xl, x2, ..., xM from the M virtual intermodulation signal generation units, changing each of the received virtual intermodulation signals into predetermined order nonlinear signals and generating the predetermined order nonlinear signals; a combination unit 122 for receiving the nonlinear signals from the signal order changing unit 121 and combining them with each other, and then generating an estimated intermodulation signal y' which is similar to an intermodulation signal desired to be removed; and a cancellation unit 123 for removing the intermodulation signal included in a fourth signal y using the generated estimated intermodulation signal y'.
  • the signal order changing unit 121 can generate predetermined order nonlinear signals for each of the received virtual intermediation signals, that is, can change a single virtual intermediation signal into first to K-th order nonlinear signals.
  • a first order nonlinear signal xl 1, a second order nonlinear signal xl2, ..., and a K-th order nonlinear signal xlK can be generated based on a virtual inter- modulation signal xl received from the first virtual intermodulation signal generation unit, and a first order nonlinear signal x21, a second order nonlinear signal x22, ..., and a K-th order nonlinear signal x2K can be generated based on a virtual intermodulation signal x2 received from the second virtual intermodulation signal generation unit.
  • all the received virtual intermodulation signals xl, x2, ..., xM are changed, so that M x K nonlinear signals can be generated.
  • the 'M' and 'K' are
  • the combination unit 122 controls (adjusts) and sets a filter coefficient, receives M x
  • a method of setting the filter coefficient in order to generate the similar estimated intermodulation signal can be performed using various algorithms.
  • the cancellation unit 123 receives the estimated intermodulation signal from the combination unit 122, and then removes an intermodulation signal included in a received fourth signal.
  • the cancellation unit 123 can remove the intermodulation signal by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal desired to be removed, from the fourth signal which includes the third signal desired to be actually received and the intermodulation signal desired to be removed.
  • the 'M' indicating the number of above-described virtual intermodulation signal generation units 110 and the 'K' indicating the order of nonlinear signals are adjusted and set based on the results of the detection performance of the third signal.
  • a device for removing an intermodulation signal generated in at least one passive device, having a different configuration can be implemented.
  • FIG. 3 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
  • the method of removing an intermodulation signal generated in at least one passive device includes a virtual intermodulation signal generation step of receiving a first signal and a second signal, and generating M virtual intermodulation signals at step S300, a nonlinear signal generation step of generating K nonlinear signals for each of the virtual intermodul ation signals at step S302, an intermodulation signal estimation step of combining nonlinear signals and generating an estimated intermodulation signal using a set filter coefficient at step S304, and an intermodulation signal cancellation step of, when a fourth signal including a third signal and an intermodulation signal are input, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal at step S306.
  • the first and second signals input at the virtual intermodulation signal generation step S300 are signals that respectively contain a first frequency component f 1 and a second frequency component f2.
  • Each of the virtual intermodulation signals generated at the virtual intermodulation signal generation step S300 is a signal containing frequency components in which sums of and subtractions between harmonic frequencies of the first and second signals are combined together.
  • the virtual intermodulation signal may include a signal containing frequency components 2fl-f2 and 2f2-fl.
  • the nonlinear signal generation step S302 is the step of generating specific order nonlinear signals based on each of the virtual intermodulation signals generated and received at the virtual intermodulation signal generation step S300.
  • K nonlinear signals can be generated with respect to a single virtual intermodulation signal, and the nonlinear signals include nonlinear signals from a first order nonlinear signal to a K-th order nonlinear signal.
  • the 'K' is a positive integer number.
  • M x K nonlinear signals are combined with each other, and then an estimated intermodulation signal which is similar to an intermodulation signal desired to be removed is generated.
  • the intermodulation signal cancellation step S306 is a step of receiving the estimated intermodulation signal and the fourth signal, and then removing the intermodulation signal included in the fourth signal.
  • the intermodulation signal is removed by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal, from the fourth signal including the third signal which is desired to be received and the intermodulation signal which distorts the third signal and reduces detection performance.
  • a plurality of (M) virtual intermodulation signals is generated, each of the generated M virtual intermodulation signals is changed into various orders nonlinear signals and then the nonlinear signals are combined, and an estimated intermodulation signal similar to an intermodulation signal desired to be removed is generated. Therefore, the intermodulation signal having nonlinear characteristics which may occur in complicated and various manners can be removed. Accordingly, signal detection performance is improved in a communication apparatus, such as a repeater or a base station, including a device for removing an intermodulation signal, thereby providing communication service to users with great satisfaction.
  • FIG. 4 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention.
  • a device for removing an intermodulation signal generated in at least one passive device includes an estimated intermodulation signal generation unit 300 for receiving a first signal 210 containing a first frequency component and a second signal 220 containing a second frequency component, generating an estimated intermodulation signal 230 containing a third frequency component, controlling the nonlinear characteristics of the generated estimated intermodulation signal, and then outputting the estimated intermodulation signal, the nonlinear characteristics of which has been controlled; and a correlation filter unit 400 for receiving a signal A 240 including an intermodulation signal generated in the passive device and the estimated intermodulation signal 230 output from the estimated intermodulation signal generation unit 300, extracting correlation between the signal A 240 and the estimated intermodulation signal 230, and then removing the intermodulation signal included in the signal A 240.
  • PIMC Passive Intermodulation Cancellator
  • the device for removing an intermodulation signal generated in at least one passive device may further include an Analog/Digital (AfD) conversion unit for converting an analog signal into a digital signal, a D/A conversion unit for converting a digital signal into an analog signal, and a coupling unit for detecting signal characteristics.
  • AfD Analog/Digital
  • Passive Intermodulation (PIM) signal which has been mentioned in the present invention is a signal which is generated in at least one passive device, such as an antenna, a feeder wire, or a distributor, within a communication apparatus because the communication apparatus uses a plurality of frequencies, causes noise to be generated at the frequencies of adjacent bands, reduces the signal-to-noise ratio of a reception frequency band, and deteriorates service quality.
  • the intermodulation signal generated in at least one passive device is referred to as an "intermodulation signal”.
  • a signal which is controlled and generated in such a way as to have high correlation with an intermodulation signal in order to remove the intermodulation signal is defined as an "estimated intermodulation signal", and the estimated inter- modulation signal can be generated in at least one active device and/or passive device.
  • the "estimated intermodulation signal" containing a third frequency component is a signal containing frequency components in which sums of and subtractions between harmonic frequencies of a first signal containing a first frequency component and a second signal containing a second frequency component are combined together. For example, if it is assumed that the first frequency is f 1 and the second frequency is f2, the estimated intermodulation signal is a signal containing third frequency components 2fl-f2 and 2f2-fl.
  • the intermodulation signal removal performance in the device for removing an intermodulation signal generated in at least one passive device differs depending on how the estimated intermodulation signal generation unit 300 generates the estimated intermodulation signal. Therefore, the present invention controls nonlinear characteristics, input characteristics, and output characteristics for the estimated intermodulation signal generation unit 300 included in the device for removing an intermodulation signal generated in at least one passive device, so that the estimated intermodulation signal, having further higher correlation with an intermodulation signal, can be generated. This will be described in detail with reference to FIG. 5.
  • FIG. 5 is a view showing an estimated intermodulation signal generation unit 300 for controlling input characteristics, nonlinear characteristics and output characteristics, and generating an estimated intermodulation signal.
  • the estimated intermodulation signal generation unit 300 for generating an estimated intermodulation signal by controlling input characteristics, nonlinear characteristics and output characteristics includes an input signal control unit 310 for controlling the input characteristics, a nonlinearity control unit 320 for controll ing the nonlinear characteristics, an output signal control unit 340 for controlling an output signal, and a filter unit 330.
  • the input signal control unit 310 controls the input characteristics by adjusting signal strength or signal waveform for input signals, that is, a first signal 210 containing a first frequency component and a second signal 220 containing a second frequency component, and then outputs a first signal 211 the input characteristics of which are controlled, and a second signal 221 the input characteristics of which are controlled.
  • the input signal control unit 310 adjusts the signal strength or signal waveform for the first signal 210 and a second signal 220 based on an input control signal received from an input signal adjustment unit 311.
  • the nonlinearity control unit 320 for controlling the nonlinear characteristics may be configured to include a nonlinear semiconductor device
  • the nonlinearity of the nonlinearity control unit 320 may vary depending on supplied power, so that the non- linearity of the estimated intermodulation signal, generated by the nonlinearity control unit 320 and then output from the nonlinearity control unit 320, can vary.
  • the estimated intermodulation signal can be adjusted to have characteristics similar to those of the intermodulation signal generated in at least one passive device.
  • the nonlinearity control unit 320 controls the nonlinear characteristics of the generated estimated intermodulation signal, and then outputs the estimated intermodulation signal, the nonlinear characteristics of which are controlled, depending on the power supplied from the power generation unit 322.
  • signals 211 and 221 which respectively contain the first and second frequency components can be included as well as the estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled.
  • the power generation unit 322 generates (produces) relevant power and then supplies the power to the nonlinearity control unit 320 in response to a power control signal received from a power adjustment unit 321.
  • a signal 231 output from the nonlinearity control unit 320 may include the signals
  • the estimated intermodulation signal generation unit 300 may include a filter unit 330 for passing through only an estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled, from among the signal 231 including the estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled, and the signals 211 and 221 which respectively contain the first and second frequency components, and for outputting a passed signal 232.
  • the output signal control unit 340 controls signal strength or signal waveform for the estimated intermodulation signal 232 from which only signals containing the third frequency component are filtered out from among the signal 231, the nonlinear characteristics of which are controlled and then output from the nonlinearity control unit. The control is performed based on an output control signal received from an output signal adjustment unit 341.
  • a signal 230, the output characteristics of which are controlled and then output by an output signal control unit 340, is the estimated intermodulation signal used to remove the intermodulation signal.
  • an (estimated) intermodulation signal which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that an estimated in- termodulation signal, which has high correlation with an intermodulation signal to be removed, can be generated, so that there is an advantage of improving cancellation performance for the intermodulation signal. Therefore, effect attributable to an intermodulation signal generated in at least one passive device can be further effectively removed, thereby providing improved service quality.
  • FIG. 6 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
  • the method of removing an intermodulation signal generated in at least one passive device includes an input signal reception step of receiving a first signal containing a first frequency component and a second signal containing a second frequency component at step S600, an estimated intermodulation signal generation step based on the control of nonlinear characteristics of generating an estimated intermodulation signal containing a third frequency component based on the received first signal and second signal, controlling the nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled, at step S604; and an intermodulation signal cancellation step of receiving a signal A, which includes an intermodulation signal generated in at least one passive device, and the estimated intermodulation signal, the nonlinear characteristics of which have been controlled, and then output, extracting correlation between the signal A and the estimated intermodulation signal, and then removing the intermodulation signal included in the signal A at step S610.
  • the estimated intermodulation signal generation step S604 based on the control of nonlinear characteristics includes receiving power generated in response to a power control signal, and then controlling the nonlinear characteristics of the estimated intermodulation signal generated based on the received power.
  • an estimated intermodulation signal can be generated by controlling input characteristics for the input signals, that is, the first signal containing the first frequency component and the second signal containing the second frequency component, or a final estimated intermodulation signal can be output by controlling the output characteristics of the generated estimated intermodulation signal.
  • the input signal control step S602 of controlling the signal strength or signal waveform for the input signals, that is, the first signal and the second signal, based on the received input control signal can be performed.
  • a filtering step S606 of passing through only the estimated intermodulation signal in which the nonlinear characteristics is controlled can be performed.
  • an output signal control step S608 of controlling signal strength or signal waveform for an estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, based on a received output control signal may be included.
  • the output signal control step S608 may be performed after the filtering step S606 is performed, as shown in FIG. 6.
  • an (estimated) intermodulation signal which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that an estimated intermodulation signal, which has high correlation with the intermodulation signal to be removed, can be generated, so that there is an advantage of improving cancellation performance for an intermodulation signal. Therefore, effect attributable to an intermodulation signal generated in at least one passive device can be further effectively removed, thereby providing improved service quality.
  • the present invention is applied to a technique for removing an intermodulation signal generated in at least one passive device within a communication apparatus, with the result that an intermodulation signal, generated in at least one passive device provided in the communication apparatus using various frequencies, and effect attributable to the intermodulation signal are effectively removed, signal distortion is prevented, and signal detection performance is improved, so that present invention is very useful invention which has an advantage of improving communication service quality.

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Abstract

A device for removing an intermodulation signal generated in at least one passive device provided in a communication apparatus is disclosed. Each of M virtual intermodulation signal generation units receives a first signal and a second signal, and generates and outputs a virtual intermodulation signal. A passive intermodulation cancellation management unit receives the virtual intermodulation signals, generates K nonlinear signals for each of the virtual intermodulation signals, and generates an estimated intermodulation signal by combining the generated nonlinear signals. When a fourth signal, including a third signal and an intermodulation signal, is received, the passive intermodulation cancellation management unit removes the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.

Description

Description
METHOD AND APPARATUS FOR REMOVING INTER- MODULATION GENERATED AT PASSIVE DEVICES
Technical Field
[1] The present invention relates, in general, to a method and apparatus for removing an intermodulation signal generated in at least one passive device, and, more particularly, to a method and apparatus for removing an intermodulation signal generated in at least one passive device, which effectively removes a complex nonlinear intermodulation signal, which is generated in at least one passive device within a communication apparatus using various frequencies and which distorts one or more signals, and removes effect attributable to the intermodulation signal, prevents the distortion of the signals, and improves signal detection performance, thereby improving communication service quality. Background Art
[2] Mobile communication services have been continuously varied, and the number of subscribers has increased. According to this trend, mobile communication service providers have obtained multiband frequencies for providing their services. That is, various frequencies have been used in order to provide service by obtaining a plurality of frequency bands in the same mobile communication method, or in order to provide service based on each of mobile communication methods by constituting a communication network such that the plurality of mobile communication methods are mixed.
[3] When service is provided using various frequencies, mobile communication service providers may have opportunities for finding a new market but should bear a burden of expense for constructing a network. Therefore, it is required to reduce costs by maximally utilizing a previously constructed communication network, and research concerning this has been progressing.
[4] However, because of the nonlinear characteristics of communication apparatuses, such as a base station and a repeater, included in a communication network, there are serious problems when various frequencies are used. In a process of processing signals, each containing frequency components which are different from each other, an intermodulation (or referred to as "cross modulation") signal which distorts a desired signal and has nonlinear characteristics is generated. In particular, because of an intermodulation signal generated in at least one passive device, such as an antenna, a feeder wire, or a distributor, provided in a communication apparatus, noise is generated in the adjacent frequency band, and a signal-to-noise ratio decreases, so that there is a problem in that the quality of service is deteriorated. Disclosure of Invention
Technical Problem
[5] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to effectively remove an intermodulation signal generated in at least one passive device within a communication apparatus using various frequencies, to prevent the distortion of signals, and to improve signal detection performance, thereby improving communication service quality.
[6] Another object of the present invention is to remove effect attributable to an intermodulation signal generated in at least one passive device provided in a communication apparatus, thereby improving service quality.
[7] A further object of the present invention is to adjust an (estimated) intermodulation signal, which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, through control for input/output characteristics and nonlinear characteristics, so that the estimated intermodulation signal, having high correlation with the intermodulation signal to be removed, is generated, thereby improving intermodulation signal removal performance. Technical Solution
[8] According to an aspect of the present invention in order to accomplish the above objects, the present invention provides a device for removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the device including M virtual intermodulation signal generation units each for receiving a first signal and a second signal, and generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit for receiving the virtual intermodulation signals, generating K nonlinear signals for each of the virtual intermodulation signals, generating an estimated intermodulation signal by combining the generated nonlinear signals, and, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
[9] According to another aspect of the present invention in order to accomplish the above objects, the present invention provides a method of removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the method including a virtual intermodulation signal generation step (a) of receiving a first signal and a second signal, and generating M virtual intermodulation signals; a nonlinear signal generation step (b) of generating K nonlinear signals for each of the virtual intermodulation signals; an intermodulation signal estimation step (c) of generating an estimated intermodulation signal by combining the nonlinear signals using a preset filter coefficient; and an intermodulation signal cancellation step (d) of, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
[10] According to further another aspect of the present invention in order to accomplish the above objects, the present invention provides a device for removing an intermodulation signal in order to remove an intermodulation signal generated in at least one passive device, the device including an estimated intermodulation signal generation unit for receiving a first signal containing a first frequency component and a second signal containing a second frequency component, generating an estimated intermodulation signal containing a third frequency component, controlling nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and a correlation filter unit for receiving a signal (A) including an intermodulation signal and the output estimated intermodulation signal, extracting correlation between the signal (A) and the estimated intermodulation signal, and then removing the intermodulation signal included in the signal (A).
[11] According to an aspect of the present invention in order to accomplish the above objects, the present invention provides a method of removing an intermodulation signal generated in at least one passive device, the method including an input signal reception step (a) of receiving a first signal containing a first frequency component and a second signal containing a second frequency component; an estimated intermodulation signal generation step (b) of generating an estimated intermodulation signal containing a third frequency component based on the received first signal and the second signal, controlling nonlinear characteristics of the generated estimated intermodulation signal, and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and an intermodulation signal cancellation step (c) of receiving a signal (A), which includes an intermodulation signal, and the estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, extracting correlation between the signal (A) and the estimated intermodulation signal, and removing the intermodulation signal included in the signal (A).
Advantageous Effects
[12] According to the present invention, an intermodulation signal generated in at least one passive device within a communication apparatus using various frequencies is effectively removed, the distortion of signals is prevented, and signal detection performance is improved, so that there is an advantage of improving communication service quality. [13] Further, according to the present invention, effect attributable to an intermodulation signal generated in at least one passive device provided in a communication apparatus is removed, so that there is an advantage of improving service quality. [14] Furthermore, according to the present invention, an (estimated) intermodulation signal, which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that the estimated intermodulation signal, having high correlation with the intermodulation signal to be removed, can be generated, so that there is an advantage of improving intermodulation signal removal performance.
Brief Description of Drawings [15] FIG. 1 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention; [16] FIG. 2 is a detailed view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention; [17] FIG. 3 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention; [18] FIG. 4 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention; [19] FIG. 5 is a view showing an estimated intermodulation signal generation unit for generating an estimated intermodulation signal by controlling input characteristics, nonlinear characteristics, and output characteristics; [20] FIG. 6 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention; and [21] FIG. 7 is a detailed flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention. [22] <Description of reference numerals of principal elements in the drawings>
[23] 100: device for removing intermodulation signal generated in at least one passive device
[24] 110: virtual intermodulation signal generation unit
[25] 120: passive intermodulation cancellation management unit
[26] 121 : signal order changing unit
[27] 122: combination unit 123: cancellation unit
[28] 300: estimated intermodulation signal generation unit
[29] 310: input signal control unit
[30] 311: input signal adjustment unit [31] 320: nonlinearity control unit
[32] 321 : input power adjustment unit
[33] 322: input power generation unit
[34] 330: filter unit 340: output signal control unit
[35] 341: output signal adjustment unit
Mode for the Invention
[36] The embodiments of the present invention will be described in detail with reference to the attached drawings below. First, when reference numerals are assigned to components of drawings, it should be noted that the same reference numerals are used throughout the different drawings to designate the same components. Further, in the following description, when it is determined that the detailed descriptions of well- known configurations or functions related to the present invention would be apparent to those skilled in the art or would obscure the gist of the present invention, they are omitted.
[37] FIG. 1 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention. First, the above-mentioned "intermodulation signal generated in at least one passive device" means an intermodulation signal which is generated in at least one passive device provided in a communication apparatus, and corresponds to a signal which causes noise to be generated in an adjacent frequency band and reduces a signal-to-noise ratio, that is, a signal desired to be removed in the present invention. Hereinafter, the "intermodulation signal generated in at least one passive device" is simply referred to as an "intermodulation signal".
[38] As shown in FIG. 1, a device 100 for removing an intermodulation signal generated in at least one passive device according to the present invention in order to remove an intermodulation signal generated in at least one passive device provided in a communication apparatus, includes M virtual intermodulation signal generation units 110 each for receiving a first signal 10 and a second signal 20, and then generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit 120 for receiving the virtual intermodulation signals, generating K nonlinear signals for each of the virtual intermodulation signals, combining the generated nonlinear signals and then generating an estimated intermodulation signal, and removing an intermodulation signal from a fourth signal 30 using the generated estimated intermodulation signal when the fourth signal, including a third signal and the intermodulation signal, is input.
[39] Each of the virtual intermodulation signal generation units 110 receives the first signal 10 containing a first frequency component f 1 and the second signal 20 containing a second frequency component f2, and then generates a virtual inter- modulation signal containing frequency components in which sums of and subtractions between harmonic frequencies of the first and second signals are combined together. The virtual intermodulation signals may include signals containing frequency components 2f l-f2 and 2f2-f 1. The virtual intermodulation signal generation unit 110 may include one or more active devices and/or passive devices.
[40] The passive intermodulation cancellation management unit 120 may include a signal order changing unit for generating predetermined order nonlinear signals based on each of the virtual intermodulation signals which are output and received from the virtual intermodulation signal generation unit 110. If, K nonlinear signals are generated with respect to a single virtual intermodulation signal received from the single virtual intermodulation signal generation unit 110, the signal order changing unit generates nonlinear signals from a first order nonlinear signal to a K-th order nonlinear signal. Here, 'K' is a positive integer. Therefore, the K nonlinear signals, generated by the passive intermodulation cancellation management unit 120, include signals ranging from the first order nonlinear signal to the K-th order nonlinear signal.
[41] The passive intermodulation cancellation management unit 120 controls (adjusts) and sets a filter coefficient, and combines M x K nonlinear signals and then generates an estimated intermodulation signal which is similar to an intermodulation signal desired to be removed. The passive intermodulation cancellation management unit 120 includes a combination unit for performing the function. A method of the combination unit of the passive intermodulation cancellation management unit 120 setting a filter coefficient in order to generate a similar estimated intermodulation signal can be performed using various algorithms.
[42] The passive intermodulation cancellation management unit 120 includes a cancellation unit for receiving the estimated intermodulation signal and the fourth signal 30, and then removing the intermodulation signal included in the fourth signal 30.
[43] The cancellation unit for performing an intermodulation signal removal function removes the intermodulation signal by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal, from the fourth signal 30, including the third signal desired to be received and the intermodulation signal which distorts the third signal and then reduces a detection performance.
[44] The 'M' indicating the number of the above-described virtual intermodulation signal generation units 110 and the 'K' indicating the order of nonlinear signals are adjusted and set based on the result of the detection performance of the third signal. When the 'M' and 'K' are differently set, a device for removing an intermodulation signal generated in at least one passive device, having a different configuration, can be implemented. [45] Each of the above-described virtual intermodulation signal generation units 110 may include various devices, such as passive devices and/or active devices, which can generate virtual intermodulation signals.
[46] The device 100 for removing an intermodulation signal generated in at least one passive device according to the present invention includes a plurality of virtual intermodulation signal generation units 110 and a passive intermodulation cancellation management unit 120 for performing a function of changing the orders of signals and combining the signals with each other. Therefore, the device 100 for removing an intermodulation signal generated in at least one passive device generates a plurality of (M) virtual intermodulation signals, changes each of the virtual intermodulation signals into various orders nonlinear signals and then combines them with each other, and generates an estimated intermodulation signal, which is similar to an intermodulation signal desired to be removed. Therefore, the device 100 for removing an intermodulation signal can remove an intermodulation signal having nonlinear characteristics which may occur in complicated and various manners. Accordingly, signal detection performance is improved for a communication apparatus, such as a repeater or a base station, including a device for removing an intermodulation signal, thereby providing communication service to users with great satisfaction.
[47] FIG. 2 is a detailed view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention.
[48] As shown in FIG. 2, a device 100 for removing an intermodulation signal generated in at least one passive device according to the present invention includes M virtual intermodulation signal generation units each for receiving a first signal and a second signal and then generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit 120 for generating an estimated intermodulation signal, and removing an intermodulation signal using the generated estimated intermodulation signal.
[49] The passive intermodulation cancellation management unit 120 will be described in detail with reference to FIG. 2. The passive intermodulation cancellation management unit 120 includes a signal order changing unit 121 for receiving virtual intermodulation signals xl, x2, ..., xM from the M virtual intermodulation signal generation units, changing each of the received virtual intermodulation signals into predetermined order nonlinear signals and generating the predetermined order nonlinear signals; a combination unit 122 for receiving the nonlinear signals from the signal order changing unit 121 and combining them with each other, and then generating an estimated intermodulation signal y' which is similar to an intermodulation signal desired to be removed; and a cancellation unit 123 for removing the intermodulation signal included in a fourth signal y using the generated estimated intermodulation signal y'.
[50] The signal order changing unit 121 can generate predetermined order nonlinear signals for each of the received virtual intermediation signals, that is, can change a single virtual intermediation signal into first to K-th order nonlinear signals. For example, a first order nonlinear signal xl 1, a second order nonlinear signal xl2, ..., and a K-th order nonlinear signal xlK can be generated based on a virtual inter- modulation signal xl received from the first virtual intermodulation signal generation unit, and a first order nonlinear signal x21, a second order nonlinear signal x22, ..., and a K-th order nonlinear signal x2K can be generated based on a virtual intermodulation signal x2 received from the second virtual intermodulation signal generation unit. In this way, all the received virtual intermodulation signals xl, x2, ..., xM are changed, so that M x K nonlinear signals can be generated. Here, the 'M' and 'K' are positive integral numbers.
[51] The combination unit 122 controls (adjusts) and sets a filter coefficient, receives M x
K nonlinear signals from the signal order changing unit 121 and combines them with each other, and generates an estimated intermodulation signal which is similar to an intermodulation signal desired to be removed. A method of setting the filter coefficient in order to generate the similar estimated intermodulation signal can be performed using various algorithms.
[52] The cancellation unit 123 receives the estimated intermodulation signal from the combination unit 122, and then removes an intermodulation signal included in a received fourth signal. The cancellation unit 123 can remove the intermodulation signal by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal desired to be removed, from the fourth signal which includes the third signal desired to be actually received and the intermodulation signal desired to be removed.
[53] The 'M' indicating the number of above-described virtual intermodulation signal generation units 110 and the 'K' indicating the order of nonlinear signals are adjusted and set based on the results of the detection performance of the third signal. When the 'M' and 'K' are differently set, a device for removing an intermodulation signal generated in at least one passive device, having a different configuration, can be implemented.
[54] FIG. 3 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
[55] As shown in FIG. 3, the method of removing an intermodulation signal generated in at least one passive device according to the present invention includes a virtual intermodulation signal generation step of receiving a first signal and a second signal, and generating M virtual intermodulation signals at step S300, a nonlinear signal generation step of generating K nonlinear signals for each of the virtual intermodul ation signals at step S302, an intermodulation signal estimation step of combining nonlinear signals and generating an estimated intermodulation signal using a set filter coefficient at step S304, and an intermodulation signal cancellation step of, when a fourth signal including a third signal and an intermodulation signal are input, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal at step S306.
[56] The first and second signals input at the virtual intermodulation signal generation step S300 are signals that respectively contain a first frequency component f 1 and a second frequency component f2.
[57] Each of the virtual intermodulation signals generated at the virtual intermodulation signal generation step S300 is a signal containing frequency components in which sums of and subtractions between harmonic frequencies of the first and second signals are combined together. The virtual intermodulation signal may include a signal containing frequency components 2fl-f2 and 2f2-fl.
[58] The nonlinear signal generation step S302 is the step of generating specific order nonlinear signals based on each of the virtual intermodulation signals generated and received at the virtual intermodulation signal generation step S300. K nonlinear signals can be generated with respect to a single virtual intermodulation signal, and the nonlinear signals include nonlinear signals from a first order nonlinear signal to a K-th order nonlinear signal. Here, the 'K' is a positive integer number.
[59] At the intermodulation signal estimation step S304, a filter coefficient is controlled
(adjusted) and set, M x K nonlinear signals are combined with each other, and then an estimated intermodulation signal which is similar to an intermodulation signal desired to be removed is generated.
[60] The intermodulation signal cancellation step S306 is a step of receiving the estimated intermodulation signal and the fourth signal, and then removing the intermodulation signal included in the fourth signal. Here, the intermodulation signal is removed by subtracting the estimated intermodulation signal, which is estimated to be similar to the intermodulation signal, from the fourth signal including the third signal which is desired to be received and the intermodulation signal which distorts the third signal and reduces detection performance.
[61] When the 'M' indicating the number of the above-described virtual intermodulation signal generation units 110 and the 'K' indicating the order of nonlinear signals are adjusted, a device for removing an intermodulation signal generated in at least one passive device having a different configuration can be implemented, and a detection performance for the third signal can be adjusted.
[62] According to the method of removing an intermodulation signal according to the present invention, a plurality of (M) virtual intermodulation signals is generated, each of the generated M virtual intermodulation signals is changed into various orders nonlinear signals and then the nonlinear signals are combined, and an estimated intermodulation signal similar to an intermodulation signal desired to be removed is generated. Therefore, the intermodulation signal having nonlinear characteristics which may occur in complicated and various manners can be removed. Accordingly, signal detection performance is improved in a communication apparatus, such as a repeater or a base station, including a device for removing an intermodulation signal, thereby providing communication service to users with great satisfaction.
[63] FIG. 4 is a schematic view showing a device for removing an intermodulation signal generated in at least one passive device according to the present invention.
[64] As shown in FIG. 4, a device for removing an intermodulation signal generated in at least one passive device (also called "Passive Intermodulation Cancellator (PIMC)") includes an estimated intermodulation signal generation unit 300 for receiving a first signal 210 containing a first frequency component and a second signal 220 containing a second frequency component, generating an estimated intermodulation signal 230 containing a third frequency component, controlling the nonlinear characteristics of the generated estimated intermodulation signal, and then outputting the estimated intermodulation signal, the nonlinear characteristics of which has been controlled; and a correlation filter unit 400 for receiving a signal A 240 including an intermodulation signal generated in the passive device and the estimated intermodulation signal 230 output from the estimated intermodulation signal generation unit 300, extracting correlation between the signal A 240 and the estimated intermodulation signal 230, and then removing the intermodulation signal included in the signal A 240. Further, the device for removing an intermodulation signal generated in at least one passive device may further include an Analog/Digital (AfD) conversion unit for converting an analog signal into a digital signal, a D/A conversion unit for converting a digital signal into an analog signal, and a coupling unit for detecting signal characteristics.
[65] The "intermodulation signal generated in at least one passive device (also called
"Passive Intermodulation (PIM) signal")" which has been mentioned in the present invention is a signal which is generated in at least one passive device, such as an antenna, a feeder wire, or a distributor, within a communication apparatus because the communication apparatus uses a plurality of frequencies, causes noise to be generated at the frequencies of adjacent bands, reduces the signal-to-noise ratio of a reception frequency band, and deteriorates service quality. Hereinafter, the intermodulation signal generated in at least one passive device is referred to as an "intermodulation signal". Further, a signal which is controlled and generated in such a way as to have high correlation with an intermodulation signal in order to remove the intermodulation signal is defined as an "estimated intermodulation signal", and the estimated inter- modulation signal can be generated in at least one active device and/or passive device. The "estimated intermodulation signal" containing a third frequency component is a signal containing frequency components in which sums of and subtractions between harmonic frequencies of a first signal containing a first frequency component and a second signal containing a second frequency component are combined together. For example, if it is assumed that the first frequency is f 1 and the second frequency is f2, the estimated intermodulation signal is a signal containing third frequency components 2fl-f2 and 2f2-fl.
[66] The intermodulation signal removal performance in the device for removing an intermodulation signal generated in at least one passive device differs depending on how the estimated intermodulation signal generation unit 300 generates the estimated intermodulation signal. Therefore, the present invention controls nonlinear characteristics, input characteristics, and output characteristics for the estimated intermodulation signal generation unit 300 included in the device for removing an intermodulation signal generated in at least one passive device, so that the estimated intermodulation signal, having further higher correlation with an intermodulation signal, can be generated. This will be described in detail with reference to FIG. 5.
[67] FIG. 5 is a view showing an estimated intermodulation signal generation unit 300 for controlling input characteristics, nonlinear characteristics and output characteristics, and generating an estimated intermodulation signal.
[68] Referring to FIG. 5, the estimated intermodulation signal generation unit 300 for generating an estimated intermodulation signal by controlling input characteristics, nonlinear characteristics and output characteristics includes an input signal control unit 310 for controlling the input characteristics, a nonlinearity control unit 320 for controll ing the nonlinear characteristics, an output signal control unit 340 for controlling an output signal, and a filter unit 330.
[69] The input signal control unit 310 controls the input characteristics by adjusting signal strength or signal waveform for input signals, that is, a first signal 210 containing a first frequency component and a second signal 220 containing a second frequency component, and then outputs a first signal 211 the input characteristics of which are controlled, and a second signal 221 the input characteristics of which are controlled. The input signal control unit 310 adjusts the signal strength or signal waveform for the first signal 210 and a second signal 220 based on an input control signal received from an input signal adjustment unit 311.
[70] Since the nonlinearity control unit 320 for controlling the nonlinear characteristics may be configured to include a nonlinear semiconductor device, the nonlinearity of the nonlinearity control unit 320 may vary depending on supplied power, so that the non- linearity of the estimated intermodulation signal, generated by the nonlinearity control unit 320 and then output from the nonlinearity control unit 320, can vary. This means that the estimated intermodulation signal can be adjusted to have characteristics similar to those of the intermodulation signal generated in at least one passive device.
[71] The nonlinearity control unit 320 controls the nonlinear characteristics of the generated estimated intermodulation signal, and then outputs the estimated intermodulation signal, the nonlinear characteristics of which are controlled, depending on the power supplied from the power generation unit 322. When the estimated intermodulation signal is output, signals 211 and 221 which respectively contain the first and second frequency components can be included as well as the estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled. The power generation unit 322 generates (produces) relevant power and then supplies the power to the nonlinearity control unit 320 in response to a power control signal received from a power adjustment unit 321.
[72] A signal 231 output from the nonlinearity control unit 320 may include the signals
211 and 221 which respectively contain the first and second frequency components as well as the estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled. Therefore, the estimated intermodulation signal generation unit 300 may include a filter unit 330 for passing through only an estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled, from among the signal 231 including the estimated intermodulation signal which contains the third frequency component, the nonlinear characteristics of which are controlled, and the signals 211 and 221 which respectively contain the first and second frequency components, and for outputting a passed signal 232.
[73] The output signal control unit 340 controls signal strength or signal waveform for the estimated intermodulation signal 232 from which only signals containing the third frequency component are filtered out from among the signal 231, the nonlinear characteristics of which are controlled and then output from the nonlinearity control unit. The control is performed based on an output control signal received from an output signal adjustment unit 341. A signal 230, the output characteristics of which are controlled and then output by an output signal control unit 340, is the estimated intermodulation signal used to remove the intermodulation signal.
[74] According to the device for removing an intermodulation signal generated in at least one passive device according to the present invention, an (estimated) intermodulation signal, which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that an estimated in- termodulation signal, which has high correlation with an intermodulation signal to be removed, can be generated, so that there is an advantage of improving cancellation performance for the intermodulation signal. Therefore, effect attributable to an intermodulation signal generated in at least one passive device can be further effectively removed, thereby providing improved service quality.
[75] FIG. 6 is a flowchart showing a method of removing an intermodulation signal generated in at least one passive device according to the present invention.
[76] As shown in FIG. 6, the method of removing an intermodulation signal generated in at least one passive device includes an input signal reception step of receiving a first signal containing a first frequency component and a second signal containing a second frequency component at step S600, an estimated intermodulation signal generation step based on the control of nonlinear characteristics of generating an estimated intermodulation signal containing a third frequency component based on the received first signal and second signal, controlling the nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled, at step S604; and an intermodulation signal cancellation step of receiving a signal A, which includes an intermodulation signal generated in at least one passive device, and the estimated intermodulation signal, the nonlinear characteristics of which have been controlled, and then output, extracting correlation between the signal A and the estimated intermodulation signal, and then removing the intermodulation signal included in the signal A at step S610.
[77] The estimated intermodulation signal generation step S604 based on the control of nonlinear characteristics includes receiving power generated in response to a power control signal, and then controlling the nonlinear characteristics of the estimated intermodulation signal generated based on the received power.
[78] In the method of removing an intermodulation signal generated in at least one passive device according to the present invention, nonlinear characteristics are controlled and then the estimated intermodulation signal is generated at step S604. Further, an estimated intermodulation signal can be generated by controlling input characteristics for the input signals, that is, the first signal containing the first frequency component and the second signal containing the second frequency component, or a final estimated intermodulation signal can be output by controlling the output characteristics of the generated estimated intermodulation signal.
[79] The method of generating an estimated intermodulation signal by controlling not only the nonlinear characteristics but also input characteristics and output characteristics will be described in detail with reference to FIG. 7.
[80] After the input signal reception step S600 is performed, the input signal control step S602 of controlling the signal strength or signal waveform for the input signals, that is, the first signal and the second signal, based on the received input control signal can be performed.
[81] After the estimated intermodulation signal generation step S604 based on the control of nonlinear characteristics is performed, a filtering step S606 of passing through only the estimated intermodulation signal in which the nonlinear characteristics is controlled can be performed.
[82] After the estimated intermodulation signal generation step S604 based on the control of nonlinear characteristics is performed, an output signal control step S608 of controlling signal strength or signal waveform for an estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, based on a received output control signal may be included. The output signal control step S608 may be performed after the filtering step S606 is performed, as shown in FIG. 6.
[83] According to the method of removing an intermodulation signal generated in at least one passive device according to the present invention, an (estimated) intermodulation signal, which is arbitrarily generated in order to remove an intermodulation signal generated in at least one passive device, can be adjusted through control for input/ output characteristics and nonlinear characteristics, with the result that an estimated intermodulation signal, which has high correlation with the intermodulation signal to be removed, can be generated, so that there is an advantage of improving cancellation performance for an intermodulation signal. Therefore, effect attributable to an intermodulation signal generated in at least one passive device can be further effectively removed, thereby providing improved service quality.
[84] In the above description, the technical spirit of the present invention has been illustrated, and those skilled in the art can perform various modifications and substitutions, without departing from the gist of the invention. Therefore, the preferred embodiments disclosed in the present invention have been illustrated not in order to limit but in order to describe the technical spirit of the present invention, and the present invention is not limited to the above-described specific embodiments. The scope of the present invention should be interpreted as disclosed in the accompanying claims, and all the technical spirit within the equivalent scopes of the claims should be interpreted that they are included in the patent rights of the present invention. Industrial Applicability
[85] As described above, the present invention is applied to a technique for removing an intermodulation signal generated in at least one passive device within a communication apparatus, with the result that an intermodulation signal, generated in at least one passive device provided in the communication apparatus using various frequencies, and effect attributable to the intermodulation signal are effectively removed, signal distortion is prevented, and signal detection performance is improved, so that present invention is very useful invention which has an advantage of improving communication service quality.

Claims

Claims
[1] A device for removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the device comprising: M virtual intermodulation signal generation units each for receiving a first signal and a second signal, and generating and outputting a virtual intermodulation signal; and a passive intermodulation cancellation management unit for receiving the virtual intermodulation signals, generating K nonlinear signals for each of the virtual intermodulation signals, generating an estimated intermodulation signal by combining the generated nonlinear signals, and, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
[2] The device according to claim 1, wherein each of the virtual intermodulation signal generation units receives the first signal containing a first frequency component (fl) and the second signal containing a second frequency component (f2), and then generates the virtual intermodulation signal containing frequency components in which sums of and subtractions between harmonic frequencies of the first and second signals are combined together.
[3] The device according to claim 1, wherein the passive intermodulation cancellation management unit comprises a signal order changing unit for generating predetermined order nonlinear signals based on each of the virtual intermodulation signals.
[4] The device according to claim 1, wherein the generated K nonlinear signals comprise signals ranging from a first order nonlinear signal to a K-th order nonlinear signal.
[5] The device according to claim 1, wherein the passive intermodulation cancellation management unit comprises a combination unit for combining M x K nonlinear signals through control of a filter coefficient, and then generating the estimated intermodulation signal similar to the intermodulation signal.
[6] The device according to claim 1, wherein the passive intermodulation cancellation management unit comprises a cancellation unit for receiving the estimated intermodulation signal and the fourth signal, and then subtracting the estimated intermodulation signal from the fourth signal, thereby removing the intermodulation signal.
[7] The device according to claim 1, wherein the 'M', which is a number of the virtual intermodulation signal generation units, and the 'K', which is an order of the nonlinear signals, are positive integers, and are adjusted depending on a result of detection performance of the third signal.
[8] The device according to claim 1, wherein a function of removing the inter- modulation signal in the passive intermodulation cancellation management unit is performed by a nonlinear filter.
[9] A method of removing an intermodulation signal generated in at least one passive device provided in a communication apparatus, the method comprising: a virtual intermodulation signal generation step (a) of receiving a first signal and a second signal, and generating M virtual intermodulation signals; a nonlinear signal generation step (b) of generating K nonlinear signals for each of the virtual intermodulation signals; an intermodulation signal estimation step (c) of generating an estimated intermodulation signal by combining the nonlinear signals using a preset filter coefficient; and an intermodulation signal cancellation step (d) of, when a fourth signal, including a third signal and an intermodulation signal, is received, removing the intermodulation signal from the fourth signal using the generated estimated intermodulation signal.
[10] The method according to claim 9, wherein the nonlinear signals, generated at the step (b), comprise signals ranging from a first order nonlinear signal to a K- th order nonlinear signal.
[11] A device for removing an intermodulation signal in order to remove an intermodulation signal generated in at least one passive device, the device comprising: an estimated intermodulation signal generation unit for receiving a first signal containing a first frequency component and a second signal containing a second frequency component, generating an estimated intermodulation signal containing a third frequency component, controlling nonlinear characteristics of the generated estimated intermodulation signal and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and a correlation filter unit for receiving a signal (A), including an intermodulation signal, and the output estimated intermodulation signal, extracting correlation between the signal (A) and the estimated intermodulation signal, and then removing the intermodulation signal included in the signal (A).
[12] The device according to claim 11, wherein the estimated intermodulation signal generation unit comprises a nonlinearity control unit for controlling the nonlinear characteristics of the generated estimated intermodulation signal, and the non- linearity control unit controls the nonlinear characteristics of the generated estimated intermodulation signal based on power supplied from a power generation unit.
[13] The device according to claim 12, wherein the power generation unit generates the power in response to a power control signal received from a power adjustment unit, and then supplies it to the nonlinearity control unit.
[14] The device according to claim 11, wherein the estimated intermodulation signal generation unit comprises an input signal control unit for controlling signal strength or signal waveform for each of the first signal and the second signal.
[15] The device according to claim 14, wherein the input signal control unit adjusts the signal strength or signal waveform based on an input control signal received from an input signal adjustment unit.
[16] The device according to claim 11, wherein the estimated intermodulation signal generation unit comprises an output signal control unit for controlling signal strength or signal waveform for the estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output.
[17] The device according to claim 16, wherein the output signal control unit controls the signal strength or signal waveform based on an output control signal received from an output signal adjustment unit.
[18] The device according to claim 11, wherein the estimated intermodulation signal generation unit comprises a filter unit for passing through only the estimated intermodulation signal, the nonlinear characteristics of which have been controlled.
[19] A method of removing an intermodulation signal generated in at least one passive device, the method comprising: an input signal reception step (a) of receiving a first signal containing a first frequency component and a second signal containing a second frequency component; an estimated intermodulation signal generation step (b) of generating an estimated intermodulation signal containing a third frequency component based on the received first signal and the second signal, controlling nonlinear characteristics of the generated estimated intermodulation signal, and then outputting the estimated intermodulation signal, the nonlinear characteristics of which have been controlled; and an intermodulation signal cancellation step (c) of receiving a signal (A), which includes an intermodulation signal, and the estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, extracting correlation between the signal (A) and the estimated intermodulation signal, and removing the intermodulation signal included in the signal (A).
[20] The device according to claim 19, wherein the step (b) comprises receiving power generated in response to a power control signal, and controlling the nonlinear characteristics of the generated estimated intermodulation signal based on the received power.
[21] The device according to claim 19, after the step (a), further comprising input signal control step of controlling signal strength or signal waveform for the first signal and the second signal based on a received input control signal.
[22] The device according to claim 19, after the step (b), further comprising a filtering step of passing through only the estimated intermodulation signal, the nonlinear characteristics of which have been controlled.
[23] The device according to claim 19, after the step (b), further comprising an output signal control step of controlling signal strength or signal waveform for the estimated intermodulation signal, the nonlinear characteristics of which have been controlled and then output, based on a received output control signal.
PCT/KR2008/005713 2007-12-26 2008-09-26 Method and apparatus for removing intermodulation generated at passive devices WO2009082084A1 (en)

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