JP2017017667A - Communication apparatus and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reduction in reception quality caused by an intermodulation signal, even when a transmission signal including signals having a plurality of frequencies is transmitted.SOLUTION: A communication apparatus includes: a transmission unit for transmitting a plurality of signals wirelessly transmitted using different frequencies; an acquisition unit for acquiring a reception signal to which an intermodulation signal caused by intermodulation between the plurality of signals has been added; and a processor that is connected to the transmission unit and the acquisition unit. The processor executes processing of generating a cancel signal corresponding to the intermodulation signal on the basis of the plurality of signals having been transmitted by the transmission unit, and superposing the generated cancel signal on the reception signal having been acquired by the acquisition unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication device and a receiving method.

  Conventionally, a duplexer may be provided in a wireless communication apparatus that shares an antenna for transmission and reception. That is, when the frequencies of the transmission signal and the reception signal are different, the transmission path and the reception path in the wireless communication apparatus are electrically separated by connecting the duplexer to the antenna. For this reason, the transmission signal does not interfere with the reception signal, and a decrease in reception quality can be suppressed.

  However, the duplexer is mainly configured using a filter, and it is difficult to completely prevent the transmission signal from leaking to the reception path. For this reason, the leaked transmission signal and the received interference signal may be intermodulated in the reception path, and reception quality may be reduced by the generated intermodulation signal. That is, when the frequency of the transmission signal is different from the frequency of the interference signal, an intermodulation signal is generated at a predetermined frequency by intermodulation of these signals. When the frequency of the intermodulation signal is included in the frequency band of the reception signal, the demodulation and decoding of the reception signal is hindered by the intermodulation signal. As a result, the accuracy of received data obtained from the received signal is reduced. In view of this, it has been studied to approximately reproduce an intermodulation signal from a transmission signal and an interference signal, and to cancel the intermodulation signal by the reproduced signal.

Special table 2009-526442

3GPP TR37.808 v12.0.0 “Passive Intermodulation (PIM) handling for Base Stations (BS) (Release 12)”

  Incidentally, in recent years, multicarrier transmission in which signals are transmitted using a plurality of carriers having different frequencies has been put into practical use. In multicarrier transmission, since a transmission signal includes signals having a plurality of frequencies, an intermodulation signal may be generated by intermodulation of signals having different frequencies. Then, the intermodulation signal generated from the transmission signal leaks to the reception path and degrades the reception quality. In particular, when the frequency of the intermodulation signal generated from the transmission signal is included in the frequency band of the reception signal, there is a problem that accurate demodulation and decoding of the reception signal becomes difficult.

  In addition, the duplexer and the antenna, and the cable connecting the duplexer and the antenna are passive elements, and the degree of contribution to the occurrence of nonlinear distortion is smaller than that of an active element such as an amplifier. However, due to a minute impedance change or non-linear characteristic in these passive elements, an intermodulation signal generated from the transmission signal may leak to the reception path and reduce the reception quality. In addition, an intermodulation signal generated from the transmission signal may be reflected to the reception path by metal or the like outside the wireless communication device, which may deteriorate the reception quality.

  Furthermore, an intermodulation signal generated from a transmission signal including signals of a plurality of frequencies may have characteristics such as power different from a theoretical value, unlike intermodulation distortion in an amplifier, for example. Therefore, simply by approximating the intermodulation signal with the conventional model, a reproduction signal that sufficiently approximates the intermodulation signal cannot be obtained, and it is difficult to cancel the intermodulation signal leaking into the reception path with the reproduction signal. is there.

  The disclosed technology has been made in view of the above points, and a communication device capable of suppressing a decrease in reception quality due to an intermodulation signal even when a transmission signal including signals of a plurality of frequencies is transmitted. An object is to provide a receiving method.

  In one aspect, a communication device disclosed in the present application includes a transmission unit that transmits a plurality of signals wirelessly transmitted at different frequencies, and a reception signal to which an intermodulation signal generated by intermodulation of the plurality of signals is added. An acquisition unit to acquire; and a processor connected to the transmission unit and the acquisition unit, the processor canceling signal corresponding to the intermodulation signal based on a plurality of signals transmitted by the transmission unit And a process of synthesizing the generated cancellation signal with the reception signal acquired by the acquisition unit.

  According to one aspect of the communication device and the reception method disclosed in the present application, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to an intermodulation signal. Play.

FIG. 1 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 1. FIG. 2 is a block diagram illustrating functions of the processor according to the first embodiment. FIG. 3 is a flowchart showing a reception process according to the first embodiment. FIG. 4 is a diagram illustrating a specific example of the cancel signal according to the first embodiment. FIG. 5 is a diagram illustrating a specific example of the effect according to the first embodiment. FIG. 6 is a flowchart showing a reception process according to the second embodiment. FIG. 7 is a diagram illustrating a specific example of the cancel signal according to the second embodiment. FIG. 8 is a diagram illustrating a specific example of the effect according to the second embodiment. FIG. 9 is a flowchart showing a reception process according to the third embodiment. FIG. 10 is a diagram illustrating a specific example of the cancel signal according to the third embodiment. FIG. 11 is a diagram illustrating a specific example of the cancel signal according to the third embodiment. FIG. 12 is a diagram illustrating a specific example of the cancel signal according to the third embodiment. FIG. 13 is a flowchart showing a reception process according to the fourth embodiment. FIG. 14 is a diagram illustrating a specific example of the cancel signal according to the fourth embodiment. FIG. 15 is a block diagram illustrating functions of the processor according to the fifth embodiment. FIG. 16 is a block diagram illustrating functions of the processor according to the sixth embodiment. FIG. 17 is a block diagram showing a configuration of a wireless communication apparatus according to the seventh embodiment. FIG. 18 is a block diagram showing a configuration of a wireless communication system according to the eighth embodiment. FIG. 19 is a block diagram illustrating a modification of the wireless communication system according to the eighth embodiment. FIG. 20 is a block diagram illustrating functions of a processor according to the eighth embodiment. FIG. 21 is a block diagram showing another modification example of the wireless communication system according to the eighth embodiment. FIG. 22 is a block diagram showing a configuration of a wireless communication system according to the ninth embodiment.

  Hereinafter, embodiments of a communication device and a reception method disclosed in the present application will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In the following description, it is assumed that the transmission signal and the reception signal have different frequencies, and the transmission signal includes a plurality of signals having different frequencies.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of radio communication apparatus 100 according to Embodiment 1. 1 includes a processor 110, a DA (Digital Analogue) converter 120, an upconverter 130, an amplifier 140, a duplexer 150, a downconverter 160, an AD (Analogue Digital) converter 170, and a memory 180.

  The processor 110 includes, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or a digital signal processor (DSP), and generates a transmission signal including a plurality of signals transmitted at different frequencies from transmission data. Further, the processor 110 obtains received data from the received signal. Furthermore, the processor 110 generates a cancel signal for canceling the intermodulation signal included in the reception signal based on the transmission signal, and cancels the intermodulation signal included in the reception signal using the cancel signal. The function of the processor 110 will be described in detail later.

  The DA converter 120 DA converts the transmission signal output from the processor 110 and outputs the obtained analog transmission signal to the up-converter 130. This transmission signal includes a plurality of signals transmitted at different frequencies.

  Upconverter 130 upconverts the transmission signal output from DA converter 120 to a radio frequency, and generates a radio transmission signal in which a plurality of signals included in the transmission signal are arranged on carriers of different frequencies. That is, up-converter 130 generates a radio transmission signal including a plurality of signals having different frequencies. Then, up-converter 130 outputs the generated wireless transmission signal to amplifier 140.

  The amplifier 140 amplifies the radio transmission signal output from the up converter 130.

  The duplexer 150 transmits a wireless transmission signal output from the amplifier 140 via a connector, a cable, and an antenna. Further, the duplexer 150 outputs a radio reception signal received by the antenna and via the cable and the connector to the down converter 160. Since the radio transmission signal and the radio reception signal have different frequencies, the duplexer 150 electrically separates the transmission path and the reception path so that the radio transmission signal does not leak into the reception path. The path between the duplexer 150 and the antenna includes passive elements such as connectors, cables, and antennas. A plurality of signals included in the radio transmission signal are intermodulated due to impedance discontinuities in these passive elements and minute nonlinear distortion generated in the passive elements, thereby generating an intermodulation signal. In addition, since the path between the duplexer 150 and the antenna is a passage path for both the radio transmission signal and the radio reception signal, an intermodulation signal generated from the radio transmission signal is added to the radio reception signal in this passage path. .

  If the path separation by the duplexer 150 is not perfect, an intermodulation signal generated by intermodulation of a plurality of signals included in the wireless transmission signal leaks to the reception path. Further, a plurality of signals included in the radio transmission signal transmitted from the antenna may be intermodulated by metal or the like outside the radio communication apparatus 100, and an intermodulation signal may be generated. The generated intermodulation signal is received by the antenna of radio communication apparatus 100 and leaks to the reception path. In particular, a third-order distortion component generated by intermodulation of two signals included in the wireless transmission signal interferes with the wireless reception signal. That is, in the present embodiment, since the frequency of the third-order distortion component is included in the frequency band of the radio reception signal, the third-order distortion component is added to the radio reception signal in the signal passing path from the duplexer 150 to the antenna. The

  The down converter 160 down-converts the radio reception signal output from the duplexer 150 to the baseband frequency, and outputs the obtained baseband frequency reception signal to the AD converter 170. A third-order distortion component generated by intermodulation of the transmission signal is added to this reception signal.

  The AD converter 170 AD converts the reception signal output from the down converter 160 and outputs the obtained digital reception signal to the processor 110.

  The memory 180 includes, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores information used by the processor 110 to execute processing. That is, the memory 180 stores, for example, parameters used when the processor 110 generates a cancel signal.

  FIG. 2 is a block diagram illustrating functions of the processor 110 according to the first embodiment. The processor 110 illustrated in FIG. 2 includes an encoding unit 111, an orthogonal modulation unit 112, a cancel signal generation unit 113, an orthogonal demodulation unit 114, a synthesis unit 115, and a decoding unit 116. Each of these processing units may be configured by hardware or software.

  Encoding section 111 encodes transmission data and outputs the obtained encoded signal to quadrature modulation section 112 and cancel signal generation section 113.

  The orthogonal modulation unit 112 performs orthogonal modulation on the encoded signal and generates a transmission signal including a plurality of signals transmitted at different frequencies. Then, quadrature modulation section 112 outputs the generated transmission signal to DA converter 120.

  The cancel signal generation unit 113 generates a cancel signal for canceling the intermodulation signal added to the reception signal in the reception path from the plurality of signals included in the transmission signal. Specifically, the cancel signal generation unit 113 acquires two baseband signals corresponding to a signal that generates a third-order distortion component of a frequency included in the frequency band of the wireless reception signal from the transmission signal, and these basebands A cancel signal is generated using a model representing a third-order distortion component by the product of the power of the signal. At this time, the cancel signal generation unit 113 reads out the power order of each baseband signal from the memory 180, and calculates a third-order distortion component based on the read order model. Then, the cancel signal generation unit 113 outputs the calculated third-order distortion component to the synthesis unit 115 as a cancel signal.

Here, the order read from the memory 180 by the cancel signal generation unit 113 is not necessarily an integer. Usually, a third-order distortion component IM (t) generated by intermodulation of two signals A (t) and B (t) having different frequencies is represented by the following equation (1).
IM (t) = A (t) ² × B (t) ^* (1)

However, in the equation (1), B (t) ^* indicates a complex conjugate of the signal B (t). As described above, in the model for calculating the normal third-order distortion component, the order related to the signal A (t) is 2, and the order related to the signal B (t) is 1, but in the present embodiment, these orders are The order is not necessarily an integer. The order is determined in advance by measuring an intermodulation signal generated by the transmission signal, for example, when the wireless communication apparatus 100 is designed or manufactured, and is stored in the memory 180.

  Specifically, the power of the third-order distortion component IM (t) when the power of one signal B (t) is fixed and the power of the other signal A (t) is changed is measured. Based on this, the order for the signal A (t) is determined in advance. Similarly, the power of the third-order distortion component IM (t) when the power of the signal A (t) is fixed and the power of the signal B (t) is changed is measured, and the signal B (t ) Is determined in advance. In determining the order, for example, the measurement result when each power is displayed in logarithm is plotted, and the slope of a straight line approximating the plot of a plurality of measurement results may be set as the order. Thus, since the order of the model corresponding to the characteristics of the wireless communication apparatus 100 is stored in the memory 180 in advance, the cancel signal generation unit 113 generates a cancel signal corresponding to the intermodulation signal generated from the transmission signal. be able to.

  The orthogonal demodulation unit 114 performs orthogonal demodulation on the received signal and outputs the obtained demodulated signal to the synthesis unit 115.

  The synthesizer 115 synthesizes the demodulated signal with the third-order distortion component output from the quadrature demodulator 114 and the cancel signal generated by the cancel signal generator 113. That is, combining section 115 cancels out the third-order distortion component added to the received signal by combining the cancel signal with the received signal.

  Decoding section 116 decodes the demodulated signal from which the third-order distortion component has been canceled by combining section 115 to obtain received data.

  Next, reception processing in the wireless communication apparatus 100 configured as described above will be described with reference to the flowchart shown in FIG.

  In wireless communication apparatus 100, transmission data is encoded by encoding section 111 (step S101), and orthogonally modulated by orthogonal modulation section 112, thereby generating a transmission signal including a plurality of signals transmitted at different frequencies. Is done. An intermodulation signal generated by intermodulation of a plurality of signals included in the transmission signal is added to the reception signal.

  Therefore, since the correspondence between the encoded baseband signal and a plurality of signals having different frequencies is known, the encoded baseband signal is added to the received signal by being input to the cancel signal generation unit 113. A cancel signal for canceling the intermodulation signal is generated. Specifically, the order of the model for obtaining the intermodulation signal is read from the memory 180 by the cancel signal generation unit 113 (step S102). Then, the cancel signal generation unit 113 uses the read order model to generate a cancel signal corresponding to the intermodulation signal added to the received signal (step S103).

More specifically, for example, the cancel signal is generated as shown in FIG. That is, the complex signal A (t) having the frequency f1 and the complex signal B (t) having the frequency f2 are included in the transmission signal, and the third-order distortion component generated by these complex signals leaks to the reception path and becomes the reception signal. Consider the case of being added. In this case, as shown in FIG. 4, the cancel signal generator 113 calculates the complex conjugate B (t) ^{* of} the complex signal B (t), and the cancel signal C (t) is obtained by the model. Here, it is assumed that the order of the complex signal A (t) is 1.8 and the order of the complex signal B (t) is 0.8 as a result of reading the model order from the memory 180. Accordingly, the cancel signal C (t) is obtained by the following equation (2).
C (t) = A (t) ^1.8 × B (t) ^{* 0.8} (2)

  The order 1.8 for the complex signal A (t) and the order 0.8 for the complex signal B (t) are determined as orders that approximate the result of measuring the power of the intermodulation signal when the wireless communication apparatus 100 is manufactured. It accurately reflects the actually generated intermodulation signal. For this reason, the cancel signal C (t) approximates the intermodulation signal generated from the transmission signal with high accuracy.

  The cancel signal generated in this way is output from the cancel signal generation unit 113 to the synthesis unit 115. On the other hand, the received signal is orthogonally demodulated by the orthogonal demodulator 114 and output to the synthesizer 115. Then, the combining unit 115 combines the reception signal to which the third-order distortion component generated from the transmission signal is added with the cancel signal (step S104), thereby removing the third-order distortion component from the reception signal. The reception signal from which the third-order distortion component has been removed is decoded by the decoding unit 116 (step S105), whereby reception data is obtained.

  In this way, a cancellation signal is generated using a model of a predetermined order based on the measurement result of the intermodulation signal, and the intermodulation signal added to the reception signal is synthesized by combining the cancellation signal with the reception signal. cancel. For this reason, the intermodulation signal generated by the intermodulation of a plurality of signals included in the transmission signal and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved. In other words, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to the intermodulation signal.

  FIG. 5 is a diagram illustrating a specific example of the effect according to the first embodiment. The received signal shown in the left diagram of FIG. 5 includes a third-order distortion component, and the power difference of the average power from the predetermined power is 122.292 dB. When the cancel signal shown in the center diagram of FIG. 5 is combined with this received signal to cancel the third-order distortion component, the receive signal shown in the right diagram of FIG. 5 is obtained. Here, the cancel signal shown in the center diagram of FIG. 5 is generated using a model of an order determined in advance based on the measurement result of the intermodulation signal, as described above. The power difference from the predetermined power of the received signal shown in the right diagram of FIG. 5 is 108.6475 dB, which is smaller than the power difference from the predetermined power of the received signal shown in the left diagram of FIG. 5 by 13.5817 dB. In other words, the 13.5817 dB intermodulation signal is canceled, and the received signal shown in the right diagram of FIG. 5 has a good spectrum close to a rectangle.

  As described above, according to the present embodiment, a cancel signal is generated using a model of an order determined in advance based on a measurement result of an intermodulation signal generated by intermodulation of a plurality of signals included in a transmission signal. Then, the cancel signal is combined with the received signal. For this reason, the intermodulation signal leaked to the reception path and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved. In other words, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to the intermodulation signal.

(Embodiment 2)
A feature of the second embodiment is that a cancel signal is generated by correcting a theoretical intermodulation signal with a correction coefficient based on a sum of amplitudes of a plurality of signals included in a transmission signal.

  The configuration of the wireless communication apparatus according to the second embodiment and the function of the processor are the same as those in the first embodiment (FIGS. 1 and 2), and thus the description thereof is omitted. In the second embodiment, the cancel signal generation method by the cancel signal generation unit 113 is different from the first embodiment. Therefore, hereinafter, a reception process for generating a cancel signal according to the second embodiment will be described.

  FIG. 6 is a flowchart showing a reception process according to the second embodiment. In FIG. 6, the same parts as those in FIG.

  In radio communication apparatus 100 according to Embodiment 2, transmission data is encoded by encoding section 111 (step S101), and is orthogonally modulated by orthogonal modulation section 112, thereby transmitting a plurality of signals transmitted at different frequencies. Is generated. An intermodulation signal generated by intermodulation of a plurality of signals included in the transmission signal is added to the reception signal.

  Therefore, since the correspondence between the encoded baseband signal and a plurality of signals having different frequencies is known, the encoded baseband signal is added to the received signal by being input to the cancel signal generation unit 113. A cancel signal for canceling the intermodulation signal is generated. Specifically, the cancel signal generation unit 113 calculates the sum of amplitudes of a plurality of signals included in the transmission signal (step S201), and calculates a correction coefficient using a function having the amplitude sum as a variable (step S202). The function used here may be a linearly changing function such as a linear function, or may be another curvedly changing function.

  Further, the cancel signal generation unit 113 obtains a theoretical intermodulation signal generated from a plurality of signals included in the transmission signal by the above equation (1) (step S203). Then, the calculated theoretical intermodulation signal is multiplied by a correction coefficient (step S204), thereby generating a cancel signal corresponding to the intermodulation signal added to the received signal.

More specifically, for example, the cancel signal is generated as shown in FIG. That is, the complex signal A (t) having the frequency f1 and the complex signal B (t) having the frequency f2 are included in the transmission signal, and the third-order distortion component generated by these complex signals leaks to the reception path and becomes the reception signal. Consider the case of being added. In this case, as shown in FIG. 7, the complex conjugate B (t) ^{* of} the complex signal B (t) is calculated by the cancel signal generation unit 113, and the theoretical third-order distortion component IM ( t) is determined. Further, the cancel signal generation unit 113 calculates the amplitude sum x of the complex signal A (t) and the complex signal B (t) by the following equation (3).
x = | A (t) | + | B (t) | (3)

  In equation (3), | α | is a symbol representing the amplitude of α. Further, the correction coefficient y is calculated by a linear function y = ax + b (a and b are predetermined coefficients) having the amplitude sum x as a variable. Then, the cancellation signal C (t) is obtained by multiplying the theoretical third-order distortion component IM (t) by the correction coefficient y.

  In the second embodiment, after obtaining a theoretical intermodulation signal IM (t), the intermodulation signal IM (t) is corrected with a correction coefficient y corresponding to the sum of amplitudes x, thereby canceling the signal C (t). Is generated. For this reason, the order of the power calculation for obtaining the intermodulation signal IM (t) is an integer, and the processing load and circuit scale related to the calculation do not increase. Further, since the theoretical intermodulation signal IM (t) is corrected based on the amplitude sum x of the signals that generate the actual intermodulation signal to generate the cancel signal C (t), the cancel signal C (t) Approximates the intermodulation signal generated from the transmission signal with high accuracy.

  The cancel signal generated in this way is output from the cancel signal generation unit 113 to the synthesis unit 115. On the other hand, the received signal is orthogonally demodulated by the orthogonal demodulator 114 and output to the synthesizer 115. Then, the combining unit 115 combines the reception signal to which the third-order distortion component generated from the transmission signal is added with the cancel signal (step S104), thereby removing the third-order distortion component from the reception signal. The reception signal from which the third-order distortion component has been removed is decoded by the decoding unit 116 (step S105), whereby reception data is obtained.

  In this way, the theoretical intermodulation signal is corrected with a correction coefficient based on the sum of the amplitudes of the actual signals to generate a cancellation signal, and the cancellation signal is combined with the reception signal, thereby intermodulation added to the reception signal. Cancel the signal. For this reason, the intermodulation signal generated by the intermodulation of a plurality of signals included in the transmission signal and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved. In other words, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to the intermodulation signal.

  FIG. 8 is a diagram illustrating a specific example of the effect according to the second embodiment. The received signal shown in the left diagram of FIG. 8 includes a third-order distortion component, and the power difference of the average power from the predetermined power is 122.292 dB as in the first embodiment (the left diagram of FIG. 5). When the cancel signal shown in the center diagram of FIG. 8 is combined with this received signal to cancel the third-order distortion component, the receive signal shown in the right diagram of FIG. 8 is obtained. Here, as described above, the cancel signal shown in the center diagram of FIG. 8 is generated by multiplying a theoretical intermodulation signal by a correction coefficient based on the sum of amplitudes of the respective signals. The power difference from the predetermined power of the reception signal shown in the right diagram of FIG. 8 is 105.4408 dB, which is 16.7884 dB smaller than the power difference from the predetermined power of the reception signal shown in the left diagram of FIG. That is, the 16.7884 dB intermodulation signal is canceled, and the received signal shown in the right diagram of FIG. 8 has a good spectrum close to a rectangle.

  As described above, according to this embodiment, a theoretical intermodulation signal is corrected with a correction coefficient based on the sum of amplitudes of actual signals to generate a cancel signal, and the cancel signal is combined with the received signal. For this reason, the intermodulation signal leaked to the reception path and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved. In other words, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to the intermodulation signal. Further, the order of the power calculation for obtaining the intermodulation signal is an integer, and the processing load and circuit scale related to the calculation do not increase.

  In the second embodiment, the correction coefficient is calculated using a function having the amplitude sum as a variable. However, the function is not necessarily used. That is, for example, a table that stores in advance a correction coefficient corresponding to the amplitude of each signal is stored in the memory 180, and the cancel signal generation unit 113 refers to the table to determine a correction coefficient corresponding to the amplitude of each signal. You may get it.

(Embodiment 3)
A feature of the third embodiment is that a cancel signal is generated by correcting a theoretical intermodulation signal with a correction coefficient based on the amplitudes of a plurality of signals included in a transmission signal. In the second embodiment, the correction coefficient is calculated based on the sum of amplitudes of a plurality of signals included in the transmission signal. However, the correction coefficient need not necessarily be calculated based on the sum of amplitudes. Therefore, in the third embodiment, an example in which a cancel signal is generated using another correction coefficient will be described.

  The configuration of the wireless communication apparatus according to the third embodiment and the function of the processor are the same as those in the first embodiment (FIGS. 1 and 2), and thus the description thereof is omitted. In the third embodiment, the cancel signal generation method by the cancel signal generation unit 113 is different from the first and second embodiments. Therefore, hereinafter, a reception process for generating a cancel signal according to the third embodiment will be described.

  FIG. 9 is a flowchart showing a reception process according to the third embodiment. In FIG. 9, the same parts as those in FIGS.

  In radio communication apparatus 100 according to Embodiment 3, transmission data is encoded by encoding section 111 (step S101), and is orthogonally modulated by orthogonal modulation section 112, whereby a plurality of signals transmitted at different frequencies are transmitted. Is generated. An intermodulation signal generated by intermodulation of a plurality of signals included in the transmission signal is added to the reception signal.

  Therefore, since the correspondence between the encoded baseband signal and a plurality of signals having different frequencies is known, the encoded baseband signal is added to the received signal by being input to the cancel signal generation unit 113. A cancel signal for canceling the intermodulation signal is generated. Specifically, the cancel signal generation unit 113 calculates the amplitude of a plurality of signals included in the transmission signal, and calculates a correction coefficient by a function using the amplitude as a variable (step S210). The function used here may be, for example, a linearly changing function such as a linear function, or may be a quadratic or higher order function.

  Further, the cancel signal generation unit 113 obtains a theoretical intermodulation signal generated from a plurality of signals included in the transmission signal by the above equation (1) (step S203). Then, the calculated theoretical intermodulation signal is multiplied by a correction coefficient (step S204), thereby generating a cancel signal corresponding to the intermodulation signal added to the received signal.

  Here, three specific examples of the cancel signal according to the third embodiment will be described with reference to FIGS.

[Specific Example 1]
First, as shown in FIG. 10, a complex signal A (t) having a frequency f1 and a complex signal B (t) having a frequency f2 are included in the transmission signal, and a third-order distortion component generated by these complex signals is received in the reception path. Let us consider a case where the signal is leaked and added to the received signal. In this case, the complex conjugate B (t) ^{* of} the complex signal B (t) is calculated by the cancel signal generation unit 113, and the theoretical third-order distortion component IM (t) is obtained by the above equation (1). Also, the correction signal y is calculated by the cancel signal generation unit 113 using the function f (| A (t) |, | B (t) |) having the amplitudes of the complex signal A (t) and the complex signal B (t) as variables. Is calculated. The correction coefficient y is multiplied by the theoretical third-order distortion component IM (t) to obtain a cancel signal C (t).

The function for calculating the correction coefficient y differs depending on the relationship between the characteristic z of the source of the intermodulation signal and the sum w of the transmission signals corresponding to the two complex signals A (t) and B (t). That is, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (4), the correction coefficient y is expressed by the following equation (5).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ (4)
y = (a ₅ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² ) + a ₃ ) (5)

_{However, a 1, a 3, a} 5, p 1, p 2 are predetermined coefficients, respectively. Similarly, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (6), the correction coefficient y is expressed by the following equation (7).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ + a ₇ w ⁷ (6)
y = (a ₇ · (q ₁ · | A (t) | ⁴ + q ₂ · | A (t) | ² · | B (t) | ² + q ₃ · | B (t) | ⁴ ) + a ₅ · ( p ₁ · | A (t) | ² + p ₂ · | B (t) | ² ) + a ₃ )) (7)

However, a ₇ , q ₁ , q ₂ , and q ₃ are also predetermined coefficients. Further, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (8), the correction coefficient y is expressed by the following equation (9).
_{z = a 1 w + a 3} w 3 + a 5 w 5 + a 7 w 7 + a 9 w 9 ... (8)
y = (a ₉ · (r ₁ · | A (t) | ⁶ + r ₂ · | A (t) | ⁴ · | B (t) | ² + r ₃ · | A (t) | ² · | B (t ) | ⁴ + r ₄ · | B (t) | ⁶ ) + a ₇ · (q ₁ · | A (t) | ⁴ + q ₂ · | A (t) | ² · | B (t) | ² + q ₃ · | B (t) | ⁴ ) + a ₅ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² ) + a ₃ )) (9)

However, a ₉ , r ₁ , r ₂ , r ₃ , r ₄ are also predetermined coefficients. It is also possible to approximate each amplitude power term with the amplitude itself. That is, for example, the correction coefficient y may be obtained by the following equation (10) instead of the above equation (9).
y = (a ₉ · (r ₁ · | A (t) | ⁶ + r ₂ · | A (t) | ⁴ · | B (t) | ² + r ₃ · | A (t) | ² · | B (t ) | ⁴ + r ₄ · | B (t) | ⁶ ) + a ₇ · (q ₁ · | A (t) | ⁴ + q ₂ · | A (t) | ² · | B (t) | ² + q ₃ · | B (t) | ⁴ ) + a ₅ · (p ₁ · | A (t) | + p ₂ · | B (t) |) + a ₃ )) (10)

In the above equation (10), the term a ₅ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² ) + a ₃ ) in the above equation (9) is the term a ₅ · (p ₁ It is approximated by | A (t) | + p ₂ · | B (t) |) + a ₃ ).

[Specific Example 2]
The transmission signal may include three or more signals, and an intermodulation signal generated by intermodulation of these three signals can be canceled. Therefore, in the second specific example, the complex signal A (t) having the frequency f1, the complex signal B (t) having the frequency f2, and the complex signal D (t) having the frequency f3 are included in the transmission signal and are generated by these complex signals. Consider a case where an intermodulation signal to be leaked to the reception path and added to the reception signal. From such three complex signals, an intermodulation signal having a frequency of the sum and difference of multiples of the frequencies of the respective complex signals is generated. Here, for example, a cancel signal that cancels an intermodulation signal generated at a frequency (f1 + f2-f3) will be described.

In this case, as shown in FIG. 11, the complex conjugate D (t) ^{* of} the complex signal D (t) is calculated by the cancel signal generation unit 113, and the theoretical intermodulation signal IM ( t) is determined.
IM (t) = A (t) × B (t) × D (t) ^* (11)

  Further, the cancel signal generation unit 113 functions f (| A (t) |, | B (t) |, | D with the amplitudes of the complex signals A (t), B (t), and D (t) as variables. The correction coefficient y is calculated by (t) |). The correction coefficient y is multiplied by the theoretical intermodulation signal IM (t) to obtain a cancel signal C (t).

The function for calculating the correction coefficient y is the relationship between the characteristic z of the source of the intermodulation signal and the sum w of the transmission signals corresponding to the three complex signals A (t), B (t), and D (t). Depending on. That is, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (12), the correction coefficient y is expressed by the following equation (13).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ (12)
y = (a ₅ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² + p ₃ · | D (t) | ² ) + a ₃ ) (13)

_{However, a 1, a 3, a} 5, p 1, p 2, p 3 are predetermined coefficients, respectively. Similarly, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (14), the correction coefficient y is expressed by the following equation (15).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ + a ₇ w ⁷ (14)
y = (a ₇ · (q ₁ · | A (t) | ⁴ + q ₂ · | B (t) | ⁴ + q ₃ · | D (t) | ⁴ + q ₄ · | A (t) | ² · | B (t) | ² + q ₅ · | B (t) | ² · | D (t) | ² + q ₆ · | D (t) | ² · | A (t) | ² ) + a ₅ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² + p ₃ · | D (t) | ² ) + a ₃ )) (15)

However, a ₇ , q ₁ , q ₂ , q ₃ , q ₄ , q ₅ , q ₆ are also predetermined coefficients.

[Specific Example 3]
The intermodulation signal is not always generated only from the third-order distortion components of a plurality of signals included in the transmission signal. That is, an intermodulation signal can be generated from distortion components of an arbitrary order of the second order or higher of a plurality of signals. Therefore, in the third specific example, the complex signal A (t) having the frequency f1 and the complex signal B (t) having the frequency f2 are included in the transmission signal, and the fifth-order distortion component generated by these complex signals leaks to the reception path. Then, consider the case where it is added to the received signal. From such two complex signals, a fifth-order distortion component having the sum and difference frequencies of the frequency of each complex signal is generated. Here, for example, a cancel signal for canceling a fifth-order distortion component generated at the frequency (3f1-2f2) will be described.

In this case, as shown in FIG. 12, the complex conjugate B (t) ^{* of} the complex signal B (t) is calculated by the cancel signal generation unit 113, and the theoretical fifth-order distortion component IM is calculated by the following equation (16). (T) is determined.
IM (t) = A (t) ³ × (B (t) ^* ) ² (16)

  Further, the correction signal y is calculated by the cancel signal generation unit 113 by the function f (| A (t) |, | B (t) |) having the amplitudes of the complex signals A (t) and B (t) as variables. Is done. The correction coefficient y is multiplied by a theoretical fifth-order distortion component IM (t) to obtain a cancel signal C (t).

The function for calculating the correction coefficient y differs depending on the relationship between the characteristic z of the source of the intermodulation signal and the sum w of the transmission signals corresponding to the two complex signals A (t) and B (t). That is, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (17), the correction coefficient y is expressed by the following equation (18).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ (17)
y = a ₅ (18)

_{However, a 1, a 3, a} 5 are predetermined coefficients, respectively. Similarly, for example, when the transmission signal sum w and the characteristic z of the intermodulation signal generation source can be expressed by the following equation (19), the correction coefficient y is expressed by the following equation (20).
z = a ₁ w + a ₃ w ³ + a ₅ w ⁵ + a ₇ w ⁷ (19)
y = (a ₇ · (p ₁ · | A (t) | ² + p ₂ · | B (t) | ² ) + a ₅ ) (20)

However, a ₇ , p ₁ , and p ₂ are also predetermined coefficients.

  As in the specific examples 1 to 3 described above, the intermodulation signal added to the reception signal is canceled by correcting the theoretical intermodulation signal by the correction coefficient based on the amplitudes of a plurality of signals included in the transmission signal. A cancel signal can be generated. At this time, a cancel signal corresponding to an intermodulation distortion component having an arbitrary second order or higher order, which is an intermodulation distortion component generated by the intermodulation of an arbitrary number of two or more signals included in the transmission signal, is generated. It is possible.

  Returning to FIG. 9, the cancel signal generated as described above is output from the cancel signal generation unit 113 to the synthesis unit 115. On the other hand, the received signal is orthogonally demodulated by the orthogonal demodulator 114 and output to the synthesizer 115. Then, the combining unit 115 combines the reception signal to which the intermodulation signal generated from the transmission signal is added and the cancel signal (step S104), thereby removing the intermodulation signal from the reception signal. The reception signal from which the intermodulation signal has been removed is decoded by the decoding unit 116 (step S105), whereby reception data is obtained.

  As described above, according to this embodiment, a theoretical intermodulation signal is corrected by a correction coefficient based on the actual signal amplitude to generate a cancel signal, and the cancel signal is combined with the received signal. For this reason, the intermodulation signal leaked to the reception path and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved.

(Embodiment 4)
The feature of the fourth embodiment is that the cancel signal is calculated from the phase of each of the plurality of signals by calculating the amplitude of the cancel signal using a function that approximates the relationship between the amplitude of each of the plurality of signals included in the transmission signal and the amplitude of the intermodulation signal. In other words, the cancel signal is generated by calculating the phase of.

  The configuration of the wireless communication apparatus according to the fourth embodiment and the function of the processor are the same as those in the first embodiment (FIGS. 1 and 2), and thus the description thereof is omitted. In the fourth embodiment, the cancel signal generation method by the cancel signal generation unit 113 is different from the first embodiment. Therefore, hereinafter, a reception process for generating a cancel signal according to the fourth embodiment will be described.

  FIG. 13 is a flowchart showing a reception process according to the fourth embodiment. In FIG. 13, the same parts as those in FIG.

  In radio communication apparatus 100 according to Embodiment 4, transmission data is encoded by encoding section 111 (step S101), and is orthogonally modulated by orthogonal modulation section 112, thereby transmitting a plurality of signals transmitted at different frequencies. Is generated. An intermodulation signal generated by intermodulation of a plurality of signals included in the transmission signal is added to the reception signal.

  Therefore, since the correspondence between the encoded baseband signal and a plurality of signals having different frequencies is known, the encoded baseband signal is added to the received signal by being input to the cancel signal generation unit 113. A cancel signal for canceling the intermodulation signal is generated. Specifically, the cancel signal generation unit 113 calculates the amplitude of the cancel signal by using an approximate function for the amplitude of each of the plurality of signals included in the transmission signal (step S301). The approximate function used here is a function that approximates the relationship between the amplitude of each signal and the amplitude of the generated intermodulation signal. In general, as the amplitude of each signal increases, the amplitude of the intermodulation signal also increases. However, as the amplitude of each signal increases, the slope at which the amplitude of the intermodulation signal increases decreases. Therefore, for example, a hyperbolic function can be used as the approximate function.

  Further, the cancel signal generation unit 113 calculates the phase of the cancel signal from the phases of the plurality of signals included in the transmission signal (step S302). That is, the phase of the intermodulation signal generated from a plurality of signals included in the transmission signal is calculated. A complex signal having the calculated amplitude and phase of the cancel signal is derived (step S303), thereby generating a cancel signal corresponding to the intermodulation signal added to the received signal.

More specifically, for example, the cancel signal is generated as shown in FIG. That is, the complex signal A (t) having the frequency f1 and the complex signal B (t) having the frequency f2 are included in the transmission signal, and the third-order distortion component generated by these complex signals leaks to the reception path and becomes the reception signal. Consider the case of being added. In this case, as shown in FIG. 14, the cancel signal generator 113 uses the hyperbolic function tanh for the amplitude of each complex signal, so that the amplitude component C _A in the intermodulation signal corresponding to each complex signal. , C _B are calculated. That is, the amplitude components C _A and C _B corresponding to the complex signals A (t) and B (t) are calculated by the following equation (21).
C _A = tanh (p · | A (t) |)
C _B = tanh (q · | B (t) |) (21)

However, in Formula (21), p and q are predetermined parameters. Further, the amplitude | C (t) | of the cancel signal corresponding to the third-order distortion component is calculated by the following equation (22).
| C (t) | = C _A ² × C _B (22)

On the other hand, assuming that the phases of the complex signals A (t) and B (t) are θ _A and θ _B , the phase θ _C of the cancel signal corresponding to the third-order distortion component is calculated by the following equation (23). .
θ _C = 2 × θ _A −θ _B (23)

Then, the complex signal having the amplitude | C (t) | and the phase θ _C calculated by the above equations (22) and (23) is the cancel signal.

  In Embodiment 4, the amplitude of the cancellation signal is calculated using an approximation function that approximates the relationship between the amplitude of the plurality of signals included in the transmission signal and the amplitude of the intermodulation signal, and the plurality of signals included in the transmission signal are calculated. The phase of the cancel signal is calculated from the phase. For this reason, it is possible to generate a cancel signal that accurately approximates the intermodulation signal generated from the transmission signal by appropriately selecting the approximate function.

  The cancel signal generated in this way is output from the cancel signal generation unit 113 to the synthesis unit 115. On the other hand, the received signal is orthogonally demodulated by the orthogonal demodulator 114 and output to the synthesizer 115. Then, the combining unit 115 combines the reception signal to which the third-order distortion component generated from the transmission signal is added with the cancel signal (step S104), thereby removing the third-order distortion component from the reception signal. The reception signal from which the third-order distortion component has been removed is decoded by the decoding unit 116 (step S105), whereby reception data is obtained.

  As described above, according to the present embodiment, the amplitude of the cancel signal is calculated using the approximation function that approximates the relationship between the amplitude of the plurality of signals included in the transmission signal and the amplitude of the intermodulation signal, and the transmission signal The phase of the cancel signal is calculated from the phases of the plurality of signals included in the signal, and the cancel signal is combined with the received signal. For this reason, the intermodulation signal leaked to the reception path and added to the reception signal can be canceled with high accuracy, and the decoding accuracy of the reception signal can be improved. In other words, even when a transmission signal including signals of a plurality of frequencies is transmitted, it is possible to suppress a decrease in reception quality due to the intermodulation signal. Further, by appropriately selecting the approximate function, a cancel signal that accurately approximates the intermodulation signal generated from the transmission signal can be generated.

  In the fourth embodiment, the amplitude of the cancel signal is calculated using the approximate function. However, the approximate function is not necessarily used. That is, for example, a table that stores in advance the amplitude of the cancel signal corresponding to the amplitude of each signal is stored in the memory 180, and the cancel signal generation unit 113 acquires the amplitude of the cancel signal by referring to the table. Also good.

(Embodiment 5)
A feature of the fifth embodiment is that an intermodulation signal is generated from a transmission signal in a passive element and a cancel signal is delayed and a phase difference is adjusted in consideration of a delay until returning to a digital circuit.

  Since the configuration of the wireless communication apparatus according to Embodiment 5 is the same as that of Embodiment 1 (FIG. 1), description thereof is omitted. In the fifth embodiment, the function of the processor 110 is different from that of the first embodiment. FIG. 15 is a block diagram illustrating functions of the processor 110 according to the fifth embodiment. 15, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In the processor 110 illustrated in FIG. 15, a delay adjustment unit 201 and a phase difference adjustment unit 202 are added to the processor 110 illustrated in FIG. 2.

  The delay adjustment unit 201 generates an intermodulation signal in a passage path between the duplexer 150 and the antenna or an external intermodulation generation source due to the transmission signal used by the cancel signal generation unit 113 to generate the cancel signal. A delay until the intermodulation signal returns to the processor 110 is detected. Specifically, the delay adjustment unit 201 calculates a correlation value between the cancellation signal generated by the cancellation signal generation unit 113 and the reception signal to which the intermodulation signal is added, and the intermodulation signal corresponding to the cancellation signal is calculated by the processor. The timing input to 110 is detected. That is, if the intermodulation signal corresponding to the cancellation signal is added to the reception signal, the correlation value between the cancellation signal and the reception signal becomes large. Therefore, the delay adjustment unit 201 has a maximum correlation value between the cancellation signal and the reception signal, for example. The delay timing of the intermodulation signal is detected by detecting the timing at which. Then, the delay adjustment unit 201 outputs a cancel signal to the phase difference adjustment unit 202 at the detected delay timing.

  The phase difference adjustment unit 202 detects the phase difference between the cancellation signal generated by the cancellation signal generation unit 113 and the intermodulation signal added to the reception signal, and adjusts the phase of the cancellation signal. Specifically, the phase difference adjustment unit 202 calculates a phase difference from the complex value of the maximum correlation value as a result of the correlation calculation in the delay adjustment unit 201, and adjusts the phase of the cancel signal by this phase difference. Then, the phase difference adjustment unit 202 outputs the cancel signal after adjusting the phase to the synthesis unit 115.

  In the fifth embodiment, an intermodulation signal generated in a passive element provided in a passing path between the duplexer 150 and the antenna or in an external intermodulation generation source is sent to the processor 110 via the down converter 160 and the AD converter 170. The delay adjustment unit 201 delays the cancel signal in consideration of the delay until the input. Further, the phase difference adjustment unit 202 adjusts the phase difference due to delay, and then inputs a cancel signal to the synthesis unit 115. For this reason, the intermodulation signal added to the received signal and the cancel signal corresponding to the intermodulation signal are input to the synthesizing unit 115 at the same timing and in the same phase, and the intermodulation signal can be reliably canceled by the cancel signal. it can.

  Note that the cancel signal generated by the cancel signal generation unit 113 may be generated by any method of the first to fourth embodiments. In addition, the location where the intermodulation signal is generated may be outside the wireless communication device, such as a cable and a connector provided in the passing path from the duplexer 150 to the antenna, and as long as it is on the path through which the transmission signal is transmitted. Good anywhere.

  As described above, according to the present embodiment, the cancel signal is delayed and the phase is adjusted in consideration of the delay and phase difference until the intermodulation signal is input to the processor. For this reason, the cancel signal corresponding to the intermodulation signal can be combined with the reception signal, and the intermodulation signal can be reliably removed from the reception signal.

(Embodiment 6)
The feature of the sixth embodiment is that the cancel signal is generated while changing the parameters for generating the cancel signal so that the cancel signal component remaining in the received signal after canceling the intermodulation signal is minimized. is there.

  The configuration of the wireless communication apparatus according to the sixth embodiment is the same as that of the first embodiment (FIG. 1), and thus the description thereof is omitted. In the sixth embodiment, the function of the processor 110 is different from that of the first embodiment. FIG. 16 is a block diagram illustrating functions of the processor 110 according to the sixth embodiment. In FIG. 16, the same parts as those in FIG. In the processor 110 illustrated in FIG. 16, a correlation value detection unit 301, a minimum power detection unit 302, and a parameter change unit 303 are added to the processor 110 illustrated in FIG.

  The correlation value detection unit 301 detects a correlation value between the cancellation signal generated by the cancellation signal generation unit 113 and the reception signal output from the synthesis unit 115. That is, correlation value detection section 301 detects the cancel signal component remaining in the received signal after the cancel signal is combined by combining section 115 and the intermodulation signal is removed. Here, when the cancellation signal generated by the cancellation signal generation unit 113 has high accuracy, the cancellation signal and the intermodulation signal added to the reception signal match, and the synthesis unit 115 cancels the cancellation signal and the intermodulation signal. Are offset. As a result, the cancel signal component remaining in the reception signal output from the synthesis unit 115 becomes small. Therefore, when the correlation value detected by the correlation value detection unit 301 is small, it can be said that the accuracy of the cancellation signal generated by the cancellation signal generation unit 113 is good.

  The minimum power detection unit 302 detects the minimum correlation value detected by the correlation value detection unit 301 (hereinafter referred to as “minimum power”) when the parameters are sequentially changed by the parameter change unit 303. That is, the minimum power detection unit 302 instructs the parameter change unit 303 to sequentially change parameters until the minimum power is detected. Then, when the minimum power is detected, the minimum power detection unit 302 instructs the parameter change unit 303 to set a parameter corresponding to the minimum power.

  The parameter changing unit 303 sequentially changes parameters when the cancel signal is generated by the cancel signal generating unit 113 in accordance with an instruction from the minimum power detecting unit 302. Specifically, for example, when the cancel signal according to Embodiment 1 is generated, the parameter changing unit 303 sequentially changes the order of the model used when the cancel signal is generated. For example, when the cancel signal according to the second embodiment is generated, the parameter changing unit 303 sequentially changes the coefficient of the function for calculating the correction coefficient from the amplitude sum. When the parameter changing unit 303 is instructed by the minimum power detecting unit 302 to set the parameter corresponding to the minimum power, the parameter when the minimum power is detected among the sequentially changed parameters is the cancel signal generating unit. Set to 113.

  In the sixth embodiment, parameters for minimizing the cancel signal component remaining in the reception signal after the cancel signals are combined are determined while sequentially changing the parameters for generating the cancel signals. That is, a parameter for generating a cancel signal that cancels the intermodulation signal added to the received signal with the highest accuracy is determined, and the cancel signal is generated based on the determined parameter. For this reason, it is possible to adaptively determine the optimum parameter based on the correlation value between the cancel signal and the received signal after combining the cancel signal, and generate a cancel signal with high accuracy.

  Note that the cancel signal generated by the cancel signal generation unit 113 may be generated by any method of the first to fourth embodiments. Then, the parameter changing unit 303 sequentially sets all or a part of the parameters used in the respective methods, and finally sets the optimum parameter corresponding to the minimum power in the cancel signal generating unit 113. Further, the location where the intermodulation signal is generated may be a cable, a connector, or the like provided in a passing path from the duplexer 150 to the antenna, and may be anywhere on the path through which the transmission signal is transmitted.

  As described above, according to the present embodiment, the correlation value between the cancel signal and the received signal after combining the cancel signal is detected while sequentially changing the parameters used when generating the cancel signal, and the correlation is detected. Determine the parameter that minimizes the value. Then, a cancel signal is generated using the determined parameter. For this reason, it is possible to adaptively determine optimal parameters, generate a cancellation signal with high accuracy, and further improve the decoding accuracy of the received signal.

(Embodiment 7)
A feature of the seventh embodiment is that, in a wireless communication apparatus in which a signal transmission path and a reception path are separated, an intermodulation signal generated outside the apparatus is canceled.

  FIG. 17 is a block diagram showing a configuration of radio communication apparatus 200 according to Embodiment 7. In FIG. In FIG. 17, the same parts as those in FIG. The radio communication apparatus 200 illustrated in FIG. 17 employs a configuration in which the duplexer 150 of the radio communication apparatus 100 illustrated in FIG. 1 is deleted and the signal transmission path and the reception path are separated. In such a configuration, even when a transmission signal including a plurality of signals transmitted at different frequencies is transmitted through a transmission path, an intermodulation signal generated by intermodulation of the plurality of signals is It does not leak into the reception path internally.

  However, when the intermodulation source S such as metal is disposed in the vicinity of the radio communication apparatus 200, a plurality of signals having different frequencies included in the radio transmission signal transmitted from the transmission antenna are generated. Intermodulate at. As a result, an intermodulation signal is generated, and the generated intermodulation signal enters the reception antenna together with the reception signal. Therefore, even if the transmission path and the reception path are separated, an intermodulation signal may be added to the reception signal.

  Therefore, processor 110 of radio communication apparatus 200 according to Embodiment 7 receives a cancel signal from a plurality of signals included in the transmission signal, similarly to processor 110 of radio communication apparatus 100 according to Embodiments 1 to 6 described above. And cancel signal is combined with the received signal. As a result, the intermodulation signal generated outside the radio communication apparatus 200 and added to the reception signal can be canceled, and deterioration of reception quality due to the intermodulation signal can be suppressed.

  As described above, according to the present embodiment, a cancel signal is generated from a plurality of signals included in a transmission signal, and an intermodulation signal generated in an external intermodulation generation source and added to a reception signal is generated by the cancel signal. cancel. For this reason, even when the transmission path and the reception path in the wireless communication apparatus are separated, the intermodulation signal added to the reception signal can be canceled with high accuracy, and the deterioration of the reception quality due to the intermodulation signal is suppressed. be able to.

(Embodiment 8)
A feature of the eighth embodiment is that an intermodulation signal is canceled in a radio communication system in which a baseband unit and a radio unit are provided separately.

  FIG. 18 is a block diagram showing a configuration of a wireless communication system according to the eighth embodiment. The wireless communication system illustrated in FIG. 18 includes a baseband unit (BBU) 300 and remote radio heads (RRHs) 400-1 and 400-2. In FIG. 18, two RRHs 400-1 and 400-2 are illustrated, but one or three or more RRHs may be connected to the BBU 300. Further, since the RRH 400-2 has the same internal configuration as the RRH 400-1, the internal configuration of the RRH 400-2 is omitted in FIG.

  The BBU 300 performs baseband processing and transmits a baseband signal including transmission data to the RRHs 400-1 and 400-2. Also, the BBU 300 receives baseband signals including received data from the RRHs 400-1 and 400-2, and performs baseband processing on the baseband signals. Specifically, the BBU 300 includes a processor 310, a memory 320, and an interface 330.

  The processor 310 includes, for example, a CPU, FPGA, or DSP, and generates a baseband signal including a plurality of signals transmitted at different frequencies from transmission data. Further, the processor 310 obtains received data from the baseband signals received from the RRHs 400-1 and 400-2. At this time, the processor 310 generates a cancel signal for canceling the intermodulation signal included in the received baseband signal based on the transmitted baseband signal, and cancels the intermodulation signal using the cancel signal.

  The memory 320 includes, for example, a RAM or a ROM, and stores information used by the processor 310 to execute processing. That is, the memory 320 stores parameters used when the processor 310 generates a cancel signal, for example.

  The interface 330 is connected to the RRHs 400-1 and 400-2 via optical fibers, for example, and transmits and receives baseband signals to and from the RRHs 400-1 and 400-2. The baseband signal transmitted by the interface 330 includes a plurality of signals transmitted at different frequencies. A plurality of signals transmitted at different frequencies may be transmitted together to either one of RRH 400-1 or 400-2, or may be transmitted separately to both RRH 400-1 or 400-2.

  RRH 400-1 and 400-2 up-convert the baseband signal received from BBU 300 to a radio frequency, and transmit the obtained radio transmission signal via an antenna. Also, RRHs 400-1 and 400-2 down-convert radio reception signals received via the antennas to baseband frequencies, and transmit the obtained baseband signals to BBU 300. Specifically, the RRHs 400-1 and 400-2 include an interface 410, a processor 415, a DA converter 420, an up converter 430, an amplifier 440, a duplexer 450, a down converter 460, and an AD converter 470.

  The interface 410 is connected to the BBU 300 through, for example, an optical fiber, and transmits / receives a baseband signal to / from the BBU 300.

  The processor 415 performs quadrature modulation on the baseband signal received by the interface 410 and outputs the result to the DA converter 420. The processor 415 may include a distortion compensation circuit that performs predistortion processing on the baseband signal because nonlinear distortion may occur due to amplification by the amplifier 440. Further, the processor 415 performs quadrature demodulation on the baseband signal output from the AD converter 470 and outputs it to the interface 410. An intermodulation signal generated by intermodulation of the transmission signal is added to the baseband signal output to the interface 410.

  The DA converter 420 DA-converts the baseband signal output from the processor 415 and outputs the obtained analog baseband signal to the upconverter 430.

  The up-converter 430 up-converts the baseband signal output from the DA converter 420 to a radio frequency and generates a radio transmission signal. Then, up-converter 430 outputs the generated wireless transmission signal to amplifier 440.

  The amplifier 440 amplifies the radio transmission signal output from the up-converter 430.

  The duplexer 450 transmits a wireless transmission signal output from the amplifier 440 via a connector, a cable, and an antenna. Further, the duplexer 450 outputs a radio reception signal received by the antenna and via the cable and the connector to the down converter 460. Since the frequencies of the radio transmission signal and the radio reception signal are different, the duplexer 450 electrically separates the transmission path and the reception path so that the radio transmission signal does not leak into the reception path.

  The path between the duplexer 450 and the antenna includes passive elements such as connectors, cables, and antennas. When a plurality of signals having different frequencies are included in the wireless transmission signal, the plurality of signals are intermodulated due to impedance discontinuities in the passive elements and minute nonlinear distortion generated in the passive elements, thereby generating an intermodulation signal. That is, since the path between the duplexer 450 and the antenna and the propagation path outside each device serve as a passage path for both the radio transmission signal and the radio reception signal, the intermodulation signals generated in these passage paths are the radio reception signals. To be added.

  On the other hand, even when a plurality of signals having different frequencies are not included in the wireless transmission signal, the frequencies of the wireless transmission signals transmitted from the RRHs 400-1 and 400-2 are different, and are mutually outside the RRHs 400-1 and 400-2. If there is a modulation source, an intermodulation signal is generated. The intermodulation signal generated outside is received by the antenna and added to the radio reception signal.

  The down-converter 460 down-converts the radio reception signal output from the duplexer 450 to a baseband frequency, and outputs the obtained baseband signal to the AD converter 470.

  The AD converter 470 AD-converts the baseband signal output from the down converter 460 and outputs the obtained digital baseband signal to the processor 415.

  In the present embodiment, an intermodulation signal generated inside or outside RRH 400-1 or 400-2 is added to a reception signal received by RRH 400-1 or 400-2. Then, the reception signal to which the intermodulation signal is added is transmitted to BBU 300. The processor 310 of the BBU 300 generates transmission signals transmitted from all the RRHs 400-1 and 400-2, and can generate a cancel signal corresponding to the intermodulation signals generated by intermodulation of these transmission signals. . Therefore, the processor 310 generates a cancel signal based on a plurality of signals transmitted from the RRHs 400-1 and 400-2, similarly to the processor 110 of the wireless communication apparatus 100 according to Embodiments 1 to 6 described above. The cancel signal is combined with the received signal. Thereby, the intermodulation signal generated inside or outside RRH 400-1 and 400-2 and added to the reception signal can be canceled, and the deterioration of the reception quality due to the intermodulation signal can be suppressed.

  As described above, according to the present embodiment, in a BBU connected to a plurality of RRHs, a cancel signal is generated based on a plurality of signals transmitted from the plurality of RRHs, and received signals received by the respective RRHs. The intermodulation signal added to is canceled by the cancel signal. For this reason, in a wireless communication system in which a baseband unit and a radio unit are provided separately, an intermodulation signal added to a received signal can be canceled with high accuracy, and a decrease in reception quality due to the intermodulation signal is suppressed. be able to.

  In the eighth embodiment, the processor 310 of the BBU 300 generates a cancel signal from the transmission signal and combines it with the reception signal. However, an apparatus having a function of canceling the intermodulation signal is provided independently. Is also possible. FIG. 19 is a block diagram illustrating a configuration of a wireless communication system including a cancel device 500 that cancels an intermodulation signal. In FIG. 19, the same parts as those in FIG. The radio communication system shown in FIG. 19 includes a cancel device 500 in addition to the BBU 300, RRH 400-1, and 400-2.

  Cancel device 500 is connected between BBU 300 and RRHs 400-1 and 400-2, and relays a baseband signal transmitted and received between BBU 300 and RRHs 400-1 and 400-2. Cancel device 500 generates a cancel signal corresponding to the intermodulation signal based on the baseband signal transmitted from BBU 300 to RRH 400-1 and 400-2, and transmits the signal from RRH 400-1 and 400-2 to BBU 300. The cancel signal is synthesized with the baseband signal to be processed. Specifically, the cancel device 500 includes interfaces 510 and 540, a processor 520, and a memory 530.

  Interface 510 is connected to BBU 300 and transmits / receives baseband signals to / from BBU 300. That is, the interface 510 receives the transmission signal generated by the processor 310 from the interface 330 of the BBU 300, and transmits the reception signal received by the RRHs 400-1 and 400-2 to the interface 330 of the BBU 300. The transmission signal received by the interface 510 from the BBU 300 includes a plurality of signals transmitted at different frequencies. A plurality of signals transmitted at different frequencies may be transmitted together to either one of RRH 400-1 or 400-2, or may be transmitted separately to both RRH 400-1 or 400-2.

  The processor 520 includes a CPU, FPGA, DSP, or the like, for example, and generates a cancel signal for canceling the intermodulation signal based on a plurality of signals received by the interface 510. Further, the processor 520 synthesizes a cancel signal with the signal received by the interface 540, and cancels the intermodulation signal added to the received signal.

  The memory 530 includes, for example, a RAM or a ROM, and stores information used by the processor 520 to execute processing. That is, the memory 530 stores, for example, parameters used when the processor 520 generates a cancel signal.

  The interface 540 is connected to the RRHs 400-1 and 400-2 via optical fibers, for example, and transmits and receives baseband signals to and from the RRHs 400-1 and 400-2. That is, the interface 540 transmits the transmission signal received from the BBU 300 to the RRHs 400-1 and 400-2, while receiving the reception signal received by the RRHs 400-1 and 400-2 from the RRHs 400-1 and 400-2. . The transmission signal transmitted from the interface 540 to the RRHs 400-1 and 400-2 includes a plurality of signals transmitted at different frequencies. A plurality of signals transmitted at different frequencies may be transmitted together to either one of RRH 400-1 or 400-2, or may be transmitted separately to both RRH 400-1 or 400-2. In addition, an intermodulation signal generated inside or outside the RRH 400-1 or 400-2 is added to the reception signal received by the interface 540 from the RRH 400-1 or 400-2.

  FIG. 20 is a block diagram illustrating functions of the processor 520. A processor 520 illustrated in FIG. 20 includes a transmission signal acquisition unit 521, a transmission signal transmission unit 522, a cancel signal generation unit 523, a reception signal acquisition unit 524, a synthesis unit 525, and a reception signal transmission unit 526. Each of these processing units may be configured by hardware or software.

  The transmission signal acquisition unit 521 acquires the transmission signal generated and transmitted in the BBU 300 from the interface 510. At this time, the transmission signal acquisition unit 521 acquires a transmission signal including a plurality of signals transmitted from the RRHs 400-1 and 400-2 at different frequencies.

  The transmission signal transmission unit 522 transmits the transmission signal acquired by the transmission signal acquisition unit 521 to the interface 540, and transmits the transmission signal to the RRHs 400-1 and 400-2.

  Cancel signal generation section 523 generates a cancel signal for canceling the intermodulation signal from a plurality of signals included in the transmission signal. Specifically, the cancel signal generation unit 523 acquires two baseband signals corresponding to intermodulation signals having frequencies included in the reception bands of the RRHs 400-1 and 400-2 from the transmission signal, and these basebands. A cancel signal is generated based on the signal. At this time, as described in the first to sixth embodiments, the cancel signal generation unit 523 cancels the signal corresponding to the intermodulation signal based on the product or amplitude of the power of a plurality of signals included in the transmission signal. Is calculated.

  The reception signal acquisition unit 524 acquires the reception signal received and down-converted by the RRHs 400-1 and 400-2 from the interface 540. At this time, reception signal acquisition section 524 acquires a reception signal to which an intermodulation signal generated due to signals transmitted from RRHs 400-1 and 400-2 at different frequencies is added.

  The combining unit 525 combines the reception signal acquired by the reception signal acquisition unit 524 with the intermodulation signal added thereto and the cancel signal generated by the cancel signal generation unit 523. That is, combining section 525 cancels the intermodulation signal added to the received signal by combining the cancel signal with the received signal.

  The reception signal transmission unit 526 transmits the reception signal whose intermodulation signal has been canceled by the synthesis unit 525 to the interface 510 and transmits it to the BBU 300.

  Thus, cancellation apparatus 500 is provided independently of BBU 300 and RRHs 400-1 and 400-2, and generates a cancellation signal based on a plurality of signals that are generated in BBU 300 and transmitted at different frequencies. Then, cancel device 500 cancels the intermodulation signal added to the reception signal received by each RRH 400-1 and 400-2 with the cancel signal.

  Furthermore, it is also possible to integrate the cancel device 500 and one RRH, and connect this RRH and another RRH to each other. That is, as shown in FIG. 21, one RRH 500a is connected to the BBU 300, and the other RRH 400-1 is connected to the RRH 500a. The RRH 500a has a function equivalent to that of the cancel device 500 described above, and executes transmission / reception of a radio signal via an antenna in the same manner as the other RRH 400-1. Since the RRH 500a has a function equivalent to that of the cancel device 500, a transmission signal wirelessly transmitted from another RRH 400-1 is transmitted to the RRH 400-1 via the RRH 500a. In other words, since transmission signals wirelessly transmitted from all RRHs pass through the RRH 500a, the RRH 500a can generate a cancel signal that cancels an intermodulation signal generated from these transmission signals. Further, since reception signals that are wirelessly received by all RRHs pass through the RRH 500a, the RRH 500a synthesizes a cancel signal with the reception signal in each RRH, and cancels the intermodulation signal added to the reception signal.

  As described above, in the wireless communication system in which one RRH 500a is connected to the BBU 300 and the other RRH 400-1 is connected to the BBU 300 via the RRH 500a, the RRH 500a can cancel the intermodulation signal.

(Embodiment 9)
A feature of the ninth embodiment is that an intermodulation signal generated when a signal having the same frequency as any one of signals is transmitted simultaneously with a plurality of signals having different frequencies is canceled.

  FIG. 22 is a block diagram showing a configuration of a wireless communication system according to the ninth embodiment. In FIG. 22, the same parts as those in FIG. 18 are denoted by the same reference numerals, and the description thereof is omitted. The radio communication system shown in FIG. 22 employs a configuration in which RRHs 400-3 and 400-4 are added to the radio communication system shown in FIG.

  In this wireless communication system, RRHs 400-1 and 400-2 transmit different signals at frequency f1, and RRHs 400-3 and 400-4 transmit different signals at frequency f3. In such a case, if there is an intermodulation generation source outside RRH 400-1 to 400-4, an intermodulation signal is generated by intermodulation of a plurality of signals including signals of the same frequency. For this reason, the processor 310 of the BBU 300 generates a cancel signal based on a plurality of signals transmitted from the RRHs 400-1 to 400-4, and adds the mutual signals added to the reception signals received by the RRHs 400-1 to 400-4. Cancel the modulation signal.

Specifically, the processor 310 generates a cancel signal by correcting the theoretical intermodulation signal with a correction coefficient based on the amplitude of a plurality of signals, as in the second and third embodiments. Here, the signals transmitted from the RRHs 400-1 and 400-2 at the frequency f1 are I ₁ and I ₂ , respectively, and the signals transmitted from the RRHs 400-3 and 400-4 at the frequency f3 are I ₃ and I ₄ , respectively. To do. With these signals, a cancel signal C (t) for canceling a third-order distortion component generated at, for example, the frequency (2f1-f3) can be expressed by the following equation (24).

_{C (t) = {p 11} | I 1 | 2 + p 21 | I 2 | 2 + p 31 | I 3 | 2 + p 41 | I 4 | 2
_{+ P 51 (I 1 · I} 2 *) + p 61 (I 1 * · I 2) + p 71 (I 3 · I 4 *) + p 81 (I 3 * · I 4)
+ P ₉₁ } ・ I ₁・ I ₁・ I ₃ ^*
_{+ {P 12 | I 1 |} 2 + p 22 | I 2 | 2 + p 32 | I 3 | 2 + p 42 | I 4 | 2
_{+ P 52 (I 1 · I} 2 *) + p 62 (I 1 * · I 2) + p 72 (I 3 · I 4 *) + p 82 (I 3 * · I 4)
+ P ₉₂ } ・ I ₁・ I ₂・ I ₃ ^*
+ {P ₁₃ | I ₁ | ² + p ₂₃ | I ₂ | ² + p ₃₃ | I ₃ | ² + p ₄₃ | I ₄ | ²
_{+ P 53 (I 1 · I} 2 *) + p 63 (I 1 * · I 2) + p 73 (I 3 · I 4 *) + p 83 (I 3 * · I 4)
+ P ₉₃ }, I ₂ , I ₂ , I ₃ ^*
_{+ {P 14 | I 1 |} 2 + p 24 | I 2 | 2 + p 34 | I 3 | 2 + p 44 | I 4 | 2
+ P ₅₄ (I ₁ ^* I ₂ ^* ) + p ₆₄ (I ₁ ^** I ₂ ) + p ₇₄ (I ₃ ^* I ₄ ^* ) + p ₈₄ (I ₃ ^** I ₄ )
+ P ₉₄ } ・ I ₁・ I ₁・ I ₄ ^*
+ {P ₁₅ | I ₁ | ² + p ₂₅ | I ₂ | ² + p ₃₅ | I ₃ | ² + p ₄₅ | I ₄ | ²
_{+ P 55 (I 1 · I} 2 *) + p 65 (I 1 * · I 2) + p 75 (I 3 · I 4 *) + p 85 (I 3 * · I 4)
+ P ₉₅ } ・ I ₁・ I ₂・ I ₄ ^*
_{+ {P 16 | I 1 |} 2 + p 26 | I 2 | 2 + p 36 | I 3 | 2 + p 46 | I 4 | 2
+ P ₅₆ (I ₁ ^* I ₂ ^* ) + p ₆₆ (I ₁ ^** I ₂ ) + p ₇₆ (I ₃ ^* I ₄ ^* ) + p ₈₆ (I ₃ ^** I ₄ )
+ P ₉₆ } · I ₂ · I ₂ · I ₄ ^* (24)
However, in the above equation (24), p _{11 to} p ₉₆ are predetermined coefficients.

In the present embodiment, since two signals of the same frequency are transmitted simultaneously, a theoretical third-order distortion component is obtained for each combination of signals. That is, the above equation (24) is divided into six parts of three rows, and each part corresponds to a signal selected as a signal of frequencies f1 and f3. For example, the first three rows of the above equation (24) multiply the square of the signal I ₁ and the complex conjugate of the signal I ₃ in order to calculate a third-order distortion component equivalent to the above equation (1). This is a part for multiplying the third-order distortion component corresponding to the combination of signals by a correction coefficient. Similarly, the next three rows of the above equation (24) calculate the product of the signals I ₁ and I ₂ and the complex conjugate of the signal I ₃ in order to calculate a third-order distortion component equivalent to the above equation (1). This is a part that multiplies and multiplies the third-order distortion component corresponding to the combination of signals by a correction coefficient.

  In this way, even when an intermodulation signal is generated by intermodulation of a plurality of signals including not only signals having different frequencies but also signals of the same frequency, the processor 310 cancels the intermodulation signal added to the received signal. A cancel signal can be generated. For this reason, the frequency of the signal transmitted from RRH 400-1 to 400-4 is not limited, and the radio communication system can be designed flexibly. In addition, for example, when a single wireless communication apparatus includes a plurality of antennas and performs MIMO (Multi Input Multi Output) communication or the like, the intermodulation signal can be canceled.

  As described above, according to the present embodiment, a cancel signal is generated based on a plurality of signals transmitted at different frequencies and the same frequency, and the intermodulation signal added to the received signal is canceled by the cancel signal. For this reason, the radio communication system can be designed flexibly, and the intermodulation signal can be canceled even in a radio communication system employing MIMO communication or the like.

  Note that the above embodiments can be implemented in combination as appropriate. Specifically, for example, the intermodulation signal is added after adjusting the delay amount and phase of the cancellation signal generated using the model of the order stored in advance by combining the first and fifth embodiments. The received signal may be combined. Further, the sixth embodiment may be combined to determine an optimal order while sequentially changing the order of the initial value, and a cancel signal may be generated using a model of the determined order. It is also possible to carry out by replacing some functions. For example, in the first embodiment, the parameter for generating the cancel signal is assumed to be a parameter with high cancellation accuracy in advance. However, by replacing the process related to the parameter setting according to the first embodiment with the process according to the sixth embodiment, even if the initial parameter value has a low cancellation accuracy, it is changed to a parameter with a high cancellation accuracy along with the operation. The

  It is also possible to describe the intermodulation signal cancellation processing described in each of the above embodiments as a program executable by a computer. In this case, this program can be stored in a computer-readable recording medium and introduced into the computer. Examples of the computer-readable recording medium include a portable recording medium such as a CD-ROM, a DVD disk, and a USB memory, and a semiconductor memory such as a flash memory.

110, 310, 415, 520 Processor 111 Encoding unit 112 Orthogonal modulation unit 113, 523 Cancel signal generation unit 114 Orthogonal demodulation unit 115, 525 Synthesis unit 116 Decoding unit 120, 420 DA converter 130, 430 Up converter 140, 440 Amplifier 150 , 450 Duplexer 160, 460 Down converter 170, 470 AD converter 180, 320, 530 Memory 201 Delay adjustment unit 202 Phase difference adjustment unit 301 Correlation value detection unit 302 Minimum power detection unit 303 Parameter change unit 330, 410, 510, 540 interface 521 Transmission signal acquisition unit 522 Transmission signal transmission unit 524 Reception signal acquisition unit 526 Reception signal transmission unit

Claims (14)

A transmitter that transmits a plurality of signals wirelessly transmitted at different frequencies;
An acquisition unit for acquiring a reception signal to which an intermodulation signal generated by intermodulation of the plurality of signals is added;
A processor connected to the transmitter and the acquisition unit;
The processor is
Based on a plurality of signals transmitted by the transmission unit, to generate a cancel signal corresponding to the intermodulation signal,
A communication apparatus that performs a process of combining the generated cancellation signal with the reception signal acquired by the acquisition unit. A transmission path including a transmission signal including a plurality of signals having different frequencies and a reception signal in a frequency band including the frequency of the intermodulation signal;
The process of combining is
The communication apparatus according to claim 1, wherein the generated cancellation signal is combined with a reception signal that passes through the passage path and is input to the processor. The process to generate is
The communication apparatus according to claim 1, wherein the cancel signal is generated using an arithmetic expression that approximates a measurement result obtained by previously measuring an intermodulation signal generated by intermodulation of the plurality of signals. The process to generate is
Calculating a correction coefficient corresponding to the amplitude of the plurality of signals;
A predetermined arithmetic expression is used to generate an intermodulation signal generated by intermodulation of the plurality of signals,
The communication apparatus according to claim 1, further comprising a process of generating a cancel signal by correcting the generated intermodulation signal with a correction coefficient. The calculation process is as follows:
The communication apparatus according to claim 4, wherein the correction coefficient is calculated using a linear function having the sum of amplitudes of the plurality of signals as a variable. The calculation process is as follows:
The communication apparatus according to claim 4, wherein the correction coefficient is calculated using a function whose variable is an even power of the amplitude of the plurality of signals. The calculation process is as follows:
The communication apparatus according to claim 4, wherein the correction coefficient is calculated using a function having variables of the magnitude of the amplitude of the plurality of signals and the magnitude of the amplitude. The process of generating the intermodulation signal includes:
5. The communication apparatus according to claim 4, wherein each of the plurality of signals is represented by a complex signal, and the intermodulation signal is obtained in the form of a complex signal or a product of complex powers of complex conjugates. The process to generate is
Calculate the amplitude of the cancellation signal using an approximation function that approximates the relationship between the amplitude of each of the plurality of signals and the amplitude of the intermodulation signal,
Calculating the phase of the cancellation signal based on the phase of each of the plurality of signals;
The communication apparatus according to claim 1, further comprising a process of generating a cancel signal having the calculated amplitude and phase. The processor is
Detecting an amount of delay until the intermodulation signal is input to the processor;
Delay the cancellation signal by the detected delay amount,
The communication apparatus according to claim 1, further comprising a process of adjusting a phase of the cancel signal by a phase difference corresponding to the detected delay amount. The process to generate is
A cancel signal is generated by performing an operation using a parameter for the plurality of signals,
The processor is
Change the parameters used in the calculation to generate the cancel signal sequentially,
Each time the parameter is changed, the correlation value between the generated cancellation signal and the received signal after combining the cancellation signal is detected,
The communication apparatus according to claim 1, further comprising: determining a parameter that minimizes the detected correlation value as a parameter for generating a cancel signal. The transmitter is
Transmitting a signal transmitted in the same frequency band as any one of the plurality of signals,
The acquisition unit
Obtaining a reception signal to which an intermodulation signal generated by intermodulation between the plurality of signals and the signal of the same frequency band is added;
The process to generate is
Calculating a correction coefficient corresponding to the amplitude of each signal for each combination of the plurality of signals and the signal of the same frequency band;
For each signal combination, a predetermined arithmetic expression is used to generate an intermodulation signal generated by intermodulation between the plurality of signals and the signal in the same frequency band,
The communication apparatus according to claim 1, further comprising: a process of generating a cancel signal by correcting the generated intermodulation signal with a correction coefficient for each combination of signals. The process to generate is
The communication apparatus according to claim 12, wherein a cancel signal is generated for some combinations of signals. Send multiple signals wirelessly transmitted at different frequencies,
Obtaining a reception signal to which an intermodulation signal generated by intermodulation of the plurality of signals is added;
Generating a cancel signal corresponding to the intermodulation signal based on a plurality of transmitted signals;
A receiving method comprising: a process of combining a generated cancellation signal with an acquired reception signal.

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