WO2021124463A1 - Wireless reception device, control circuit, storage medium, and wireless communication method - Google Patents

Abstract

A wireless reception device (100) for receiving a signal that includes an intermodulation product which is a distortion component generated between carriers when a transmission device amplifies a signal that includes a plurality of carriers by a single amplifier, is characterized by having a reference signal generation unit (104) for generating a reference signal with which the respective signal components of the plurality of carriers are estimated, intermodulation product estimation units (105, 115) for estimating an intermodulation product included in the received signal on the basis of the plurality of reference signals, and intermodulation product cancelation units (107, 117) for subtracting the estimated intermodulation product from the received signal.

Description

Wireless receivers, control circuits, storage media and wireless communication methods

The present invention relates to a wireless receiver, a control circuit, a storage medium, and a wireless communication method for communicating using signals including a plurality of carriers.

In wireless communication systems, technology that compensates for the effects of signal distortion is required in order to transmit information accurately. Factors that cause distortion in the signal include intersymbol interference in the transmission line and an amplifier that amplifies the signal with power including a non-linear region on the transmitting side. Non-linear distortion occurs when the signal is amplified with power that includes the non-linear region of the amplifier to improve power efficiency.

Patent Document 1 discloses a receiving device capable of simultaneously compensating for non-linear distortion and linear distortion in single carrier transmission. According to the technique disclosed in Patent Document 1, in a receiving device that receives a signal obtained by amplifying a single carrier with a single amplifier, it is possible to compensate for non-linear distortion with an equalizer as well as linear distortion.

Further, in a multi-carrier system such as OFDM (Orthogonal Frequency Division Multiplexing), it is known that when a signal containing a plurality of carriers is amplified by a single amplifier, non-linear distortion called intermodulation distortion occurs between the carriers. ing. Non-Patent Document 1 discloses a technique for suppressing nonlinear distortion on the transmitting side in a multi-carrier type wireless communication system.

International Publication No. 2019/171551

Yuki Abe, Yasushi Yamao "Broadband Nonlinear Compensation Method by Spectral Decomposition Parallel Signal Processing" Shingaku Giho RCS2018-195 November 2018

However, according to the technique described in Patent Document 1, it is possible to compensate for the non-linear distortion and the linear distortion that occur in the carriers, but it is not possible to remove the intermodulation distortion that occurs between the carriers. Further, according to the technique described in Non-Patent Document 1, in order to remove the intermodulation distortion, a circuit for feeding back the transmission signal is required in the transmission device, which causes a problem that the circuit scale of the signal processing circuit is increased. was there. For example, when there is a restriction on the circuit scale of the transmitting device such as a downlink in a satellite communication system in which the transmitting device is a satellite, it is difficult to apply the technique described in Non-Patent Document 1.

The present invention has been made in view of the above, and an object of the present invention is to obtain a wireless receiving device capable of compensating for intermodulation distortion while suppressing an increase in circuit scale in a transmitting device.

In order to solve the above-mentioned problems and achieve the object, the wireless receiving device according to the present invention is a distortion component generated between carriers when a transmitting device amplifies a signal containing a plurality of carriers with a single amplifier. A reference signal generator that receives a signal containing an intermodulation component and generates a reference signal that estimates the signal components of each of a plurality of carriers, and an intermodulation component included in the received signal is estimated based on the plurality of reference signals. It is characterized by having an intermodulation component estimation unit for estimating the intermodulation component, and an intermodulation component canceling unit for subtracting the estimated intermodulation component from the received signal.

The wireless receiving device according to the present invention has an effect that it is possible to compensate for intermodulation distortion while suppressing an increase in the circuit scale in the transmitting device.

The figure which shows the functional structure of the wireless receiver device which concerns on Embodiment 1 of this invention. The figure which shows the format example of the signal received by the wireless receiver shown in FIG. The figure which shows the carrier frequency arrangement of each of the plurality of carrier components included in the received signal of the wireless receiver shown in FIG. The figure which shows the functional structure example of the intermodulation component estimation part shown in FIG. A flowchart for explaining the operation of the wireless receiver shown in FIG. The figure which shows the functional structure of the wireless receiver device which concerns on Embodiment 2 of this invention. A flowchart for explaining the operation of the wireless receiver shown in FIG. The figure which shows the configuration example when the wireless receiver device which concerns on Embodiments 1 and 2 of this invention is realized by hardware The figure which shows the configuration example in the case where a part of the function of the wireless receiver device which concerns on Embodiment 1 and 2 of this invention is realized by software

Hereinafter, the wireless receiving device, the control circuit, the storage medium, and the wireless communication method according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing a functional configuration of the wireless receiver 100 according to the first embodiment of the present invention. The wireless receiver 100 includes antennas 101 and 111, RF (Radio Frequency) circuit units 102 and 112, nonlinear equalization units 103 and 113, a reference signal generation unit 104, and intermodulation component estimation units 105 and 115. It has a rigid determination unit 106, 116, an intermodulation component canceling unit 107, 117, and an FEC (Forward Error Correction) unit 108, 118.

The wireless receiving device 100 receives a signal including a plurality of carriers from a transmitting device (not shown). The transmitter amplifies a signal containing a plurality of carriers with a single amplifier. At this time, the transmitter of the transmitter amplifies the signal with the power including the non-linear region of the amplifier in order to improve the power efficiency. In this case, the amplified signal contains a non-linear distortion component. The non-linear distortion component generated at the time of amplification includes, for example, a non-linear distortion component within a carrier, which is a distortion generated when signals in one single carrier-modulated band interfere with each other by non-linear amplification. Further, when a signal containing a plurality of carriers is amplified by a single amplifier, in a modulation method having a large peak power as compared with other modulation methods such as OFDM, the signals interfere with each other and distortion occurs. May occur. The non-linear distortion component generated between carriers is called an intermodulation component.

FIG. 2 is a diagram showing a format example of a signal received by the wireless receiving device 100 shown in FIG. The received signal of the wireless receiver 100 includes a header 11, a payload 12, and a pilot 13. The pilot 13 is a signal having a predetermined pattern between transmission and reception, and indicates a pattern defined by a standard used in satellite communication such as the DVB-S (Digital Video Broadcasting-Satellite) standard.

Conventionally, in satellite communication, multi-carrier transmission using a modulation method such as OFDM, which has a higher peak power than other modulation methods, has not been used. However, if the signal bandwidth per carrier is expanded, a modem can be used. Since parallelization becomes difficult and the influence of frequency characteristics becomes large, it is necessary to consider a transmitter that can transmit multiple carriers at adjacent frequencies by frequency multiplexing and amplify them with a single amplifier. It has become to.

Each of the antennas 101 and 111 receives signals of carriers different from each other. The antenna 101 is connected to the RF circuit unit 102 and outputs a received signal to the RF circuit unit 102. The antenna 111 is connected to the RF circuit unit 112 and outputs a received signal to the RF circuit unit 112.

Each of the RF circuit units 102 and 112 converts the received signal into a baseband signal tuned to each carrier. The RF circuit unit 102 is connected to each of the non-linear equalization unit 103 and the intermodulation component estimation unit 105, and outputs a baseband signal to each of the non-linear equalization unit 103 and the intermodulation component estimation unit 105. The RF circuit unit 112 is connected to each of the non-linear equalization unit 113 and the intermodulation component estimation unit 115, and outputs a baseband signal to each of the non-linear equalization unit 113 and the intermodulation component estimation unit 115. Each of the RF circuit units 102 and 112 may be an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit.

Each of the non-linear equalizing units 103 and 113 performs a process of removing the distortion component of the own carrier included in the baseband signal. Here, the distortion component of the own carrier is a distortion component generated in the carrier, and is a non-linear distortion component in the carrier caused by amplifying the signal with the power including the non-linear region of the amplifier on the transmitter side. Further, the distortion component of the own carrier may include a distortion component due to intersymbol interference.

The non-linear equalization units 103 and 113 can use the non-linear equalization method shown in International Publication No. 2019/171551 (Patent Document 1). Each of the non-linear equalizers 103 and 113 has a linear filter and a non-linear filter, performs propagation path estimation using known signals, and controls the filter coefficients of the linear filter and the non-linear filter based on the estimation result. Therefore, it is possible to compensate for the linear distortion and the non-linear distortion of the own carrier. Specifically, the nonlinear equalization units 103 and 113 perform the first equalization processing using a fixed filter coefficient and a linear filter without using the nonlinear filter, and receive the received signal after the first equalization processing. When the synchronous processing is performed using and the predetermined conditions are satisfied, the second equalization processing using both the linear filter and the non-linear filter may be started. The second equalization process is an adaptive equalization process that controls the filter coefficient using an adaptive equalization algorithm such as LMS (Least Mean Square). The condition for starting the second equalization process is a condition for determining that the synchronization accuracy is equal to or higher than the standard. For example, the time from the start of the synchronization process, the number of processing samples, and the condition after the equalization process are performed. It can be based on at least one of the signal qualities. The non-linear equalization unit 103 outputs the baseband signal after performing the non-linear equalization processing to remove the distortion component of its own carrier to the intermodulation component estimation unit 105 and the intermodulation component canceling unit 107. The non-linear equalization unit 113 outputs the baseband signal after performing the non-linear equalization processing to remove the distortion component of its own carrier to the intermodulation component estimation unit 115 and the intermodulation component canceling unit 117.

Subsequently, the received signal of the wireless receiving device 100 will be described. As for the received signal of the wireless receiving device 100, the signal including a plurality of carriers is amplified by a single amplifier in the transmitting device. When the input signal s, 1 coefficients of order distortion a _1, 3 coefficient a ₃ of order distortion to the amplifier, the output signal y from the amplifier is represented by the following equation (1).

Components of the two carriers in this embodiment was the S _L, S _H respectively, when the frequency offset component of the carrier and omega, the input signal s is expressed by the following equation (2).

Here, S _L, S _H is, PSK (Phase Shift Keying), APSK (Amplitude Phase Shift Keying), QAM (Quadrature Amplitude Modulation) is a complex signal, such as.

Figure 3 is a diagram showing the respective carrier frequency arrangement of a plurality of carrier components S _L, S _H included in the received signal of the wireless reception device 100 shown in FIG. Here, the frequency offset component of the carrier is ω. The output signal y from the amplifier when the signal represented by the formula (2) is passed through the amplifier is represented by the following formula (3).

From the mathematical formula (3), it can be seen that the received signal of the wireless receiving device 100 includes a plurality of components shown in the following mathematical formula (4).

When the receiving unit composed of the antenna 101 and the RF circuit unit 102 of FIG. 1 tunes to the carrier of the exp (−jωt) component, the component included in the received signal is represented by the following mathematical formula (5).

The reference signal generation unit 104 uses the hardness determination results of the hardness determination units 106 and 116 that perform the hardness determination process based on the signals input to the FEC units 108 and 118, and the two carrier components S included in the received signal. _L, and calculates the S _H, to generate a carrier component S _L, the reference signal and the estimation of S _H # 1 and the reference signal # 2. The reference signal generation unit 104 outputs the generated reference signal # 1 and reference signal # 2 to the intermodulation component estimation units 105 and 115. For example, if the intermodulation component estimator 105 performs the processing of carrier components S _L, the reference signal generating unit 104 outputs the reference signal # 1 of carrier components S _L intermodulation component estimator 105. If the intermodulation component estimator 115 performs processing of the carrier components S _H, the reference signal generating unit 104 outputs the reference signal # 2 of carrier components S _H intermodulation component estimator 115.

The reference signal generation unit 104 may generate a reference signal by using a hard determination result for operating in a determination-oriented type or a known sequence such as a pilot 13. For example, as shown in FIG. 2, since whether or not a known sequence is included changes depending on the reception time, the reference signal generation unit 104 uses the known sequence to generate a reference signal at the reception time including the known sequence. A reference signal may be generated using the rigid determination result at a reception time that is generated and does not include a known sequence. Alternatively, the reference signal generation unit 104 may generate a reference signal from the tentative determination signal corresponding to the payload 12. The tentative determination signal is generated by, for example, the rigid determination processing unit 106. The hard determination processing unit 106 can generate a determination result by performing determination processing not only in a hard limit operation but also in a soft limit operation, and can generate a provisional determination signal indicating the determination result. Specifically, the rigid determination processing unit 106 approximates the output of the sigmoid function that approximates the sign function to the determination function that receives the received signal as an input. By adjusting the parameters of the sigmoid function, it is possible to realize a hard judgment operation and a soft judgment operation, respectively. By selecting a parameter close to the soft judgment operation, the effect of reducing the error propagation at the time of judgment error due to interference can be expected at the cost of reducing the noise removal effect.

FIG. 4 is a diagram showing a functional configuration example of the intermodulation component estimation units 105 and 115 shown in FIG. Each of the intermodulation component estimation units 105 and 115 has a known signal holding unit 201, an intermodulation basic component generation unit 202, a received signal storage unit 203, a linear combination coefficient generation unit 204, and a replica generation unit 205. ..

The known signal holding unit 201 holds known signals such as a pilot in a signal defined by a standard such as DVB-S2 and DVB-S2X, a SOF (Start Of Frame) included in a header, and a synchronization data string in a super frame. ..

The intermodulation basic component generation unit 202 generates an intermodulation basic component based on the known signal held by the known signal holding unit 201 and the reference signal # 1 and the reference signal # 2 obtained from the reference signal generation unit 104. To do. The intermodulation basic component is each component shown in the above formula (5). The intermodulation basic component generation unit 202 outputs the generated intermodulation basic component to each of the linear combination coefficient generation unit 204 and the replica generation unit 205.

The received signal storage unit 203 stores the received signals from the RF circuit units 102 and 112. Specifically, the received signal storage unit 203 of the intermodulation component estimation unit 105 stores the received signal from the RF circuit unit 102, and the received signal storage unit 203 of the intermodulation component estimation unit 115 is from the RF circuit unit 112. The received signal of is accumulated. The reception signal storage unit 203 supplies the linear combination coefficient generation unit 204 with a signal sequence at a time corresponding to the value of the intermodulation basic component generated by the intermodulation basic component generation unit 202.

The linear combination coefficient generation unit 204 uses the intermodulation basic component generated by the intermodulation basic component generation unit 202 to perform a coefficient estimation process for expressing the received signal obtained by the reception signal storage unit 203 as a linear combination. Specifically, the linear combination coefficient generator 204 may obtain the coefficient by correlating the received signal with each of the plurality of intermodulation basic components, or may obtain the coefficient by using the modeling of the least squares method. It may be calculated. When correlation is used, the linear combination coefficient generator 204 may use reference signals at a plurality of times with respect to the received signal to perform sliding correlation between the signals. This makes it possible to obtain an estimation result that reflects distortion such as a memory effect in which an input signal at a plurality of times affects an output signal at a certain sample time. Further, when modeling by the least squares method, the linear combination coefficient generator 204 adds the values of the intermodulation basic components at a plurality of times to the explanatory variables and solves the least squares method to obtain distortion such as a memory effect. Can be accommodated.

By increasing the estimation variable, it becomes possible to obtain an estimation result that reflects distortion such as the memory effect, but it becomes more susceptible to estimation errors. Therefore, especially in an environment where the SNR (Signal to Noise Ratio) is low and it is easily affected by noise, the linear combination coefficient generator 204 removes terms with a small contribution from the explanatory variables or fixes the coefficient value to "0". By doing so, the influence of the estimation error can be reduced. For example, among the intermodulation basic components shown in the equation (5), the exp (j4ωt) described at the end is a component that is modulated to the position of 4ω outside the own band, and is a filter in the wireless receiver 100. Often removed by. Therefore, the linear combination coefficient generation unit 204 may exclude exp (j4ωt) from the explanatory variables when generating the coefficient.

The linear combination coefficient generation unit 204 may perform the estimation process from the received signal from which the desired wave component has been removed prior to the estimation process. That is, in the present embodiment, since the reception level and the phase of the outputs of the nonlinear equalization units 103 and 113 are corrected, the linear combination coefficient generation unit 204 of the intermodulation component estimation units 105 and 115 is based on the reference signal. Te, after subtracting the reference signal # 1 components from the received signal (corresponding to S _L), may be performed estimation process described above. In addition, the coefficient of linear combination is assumed to fluctuate slowly over time in satellite communications. Therefore, the linear combination coefficient generator 204 may use the result of time averaging using the results estimated in a plurality of frames, or may use a least squares-based sequential algorithm such as LMS or RLS (Recursive Least Squares). It may be used, or the result obtained by averaging the estimation result with an IIR (Infinite Impulse Response) filter may be used. This makes it possible to reduce the influence of noise. The linear combination coefficient generation unit 204 outputs the generated coefficient to the replica generation unit 205.

The replica generation unit 205 generates a replica of the intermodulation component included in the received signal by using the coefficient generated by the linear combination coefficient generation unit 204 and the intermodulation basic component generated by the intermodulation basic component generation unit 202. .. The replica generation unit 205 generates a replica of the intermodulation component by linearly combining the values obtained by multiplying each of the plurality of intermodulation basic components by the estimated coefficient. In the present embodiment, the coefficient is estimated for the received signal, and the signal is canceled for the output results of the nonlinear equalization units 103 and 113. Therefore, the replica generation unit 205 performs the same correction as the nonlinear equalization units 103 and 113 with respect to the result of the linear combination by using the equalization filter coefficient output by the nonlinear equalization units 103 and 113. To generate the final intermodulation component estimate. In the present embodiment, since a high-order distortion component is generated by performing the non-linear equalization processing, the coefficient is estimated using the received signal before the non-linear equalization.

Return to the explanation in Fig. 1. The intermodulation component canceling units 107 and 117 subtract the intermodulation component estimated value from the output signals of the nonlinear equalization units 103 and 113 based on the intermodulation component estimated value, and obtain the equalization result when there is no intermodulation. Generate the corresponding received signal. The intermodulation component canceling unit 107 outputs the generated received signal to each of the FEC unit 108, the rigid determination unit 106, and the non-linear equalization unit 103. The intermodulation component canceling unit 117 outputs the generated received signal to each of the FEC unit 118, the rigid determination unit 116, and the non-linear equalization unit 113.

The FEC units 108 and 118 are error correction / decoding units that generate a soft judgment value or a hard judgment value from a received signal and perform an error correction / decoding process.

The non-linear equalization units 103 and 113 may repeat the non-linear equalization process again using the received signal after canceling the intermodulation component. In this case, the intermodulation component canceling units 107 and 117 do not cancel the intermodulation component for the result of the second nonlinear equalization, and output the nonlinear equalization result as it is to the FEC units 108 and 118. ..

The wireless receiver 100 improves reception performance even in a communication system in which each carrier has a bandwidth of 100 MHz class or more, includes linear distortion and non-linear distortion within each carrier, and includes intermodulation distortion between carriers. It is possible. The technique described in the present embodiment utilizes the fact that the time variation of the propagation path is gradual and the compensation coefficient can be estimated with high accuracy in an environment where a large SNR can be obtained. It is a reception technology suitable for the system. In the present embodiment, the reception performance can be improved without performing complicated processing on the transmitting side. By using the above technology, the transmitting side only performs processing with a relatively small amount of calculation, such as band limiting of the transmitted signal and simple DPD (Digital Pre-Distortion) for the purpose of signal clipping, and the receiving side. It can be configured to remove distortion.

The intermodulation component estimation units 105 and 115 can hold and use the estimated coefficients while the same transmission device drives the amplifier at the same drive point and receives the generated transmission signal. However, the drive points of the amplifier may fluctuate. For example, when changing the modulation method used by the transmitting device, the transmitting device is equipped with a plurality of amplifiers, and when the amplifiers used are switched in a time-multiplexed manner, the transmitting device which is the communication partner of the wireless receiving device 100 is switched. For example. In such a case, the transmitting device inserts the driving point identification information for identifying the driving point of the amplifier in use into the transmission signal and transmits the driving point identification information to the wireless receiving device 100. The wireless receiver 100 changes the coefficient used to estimate the intermodulation component based on the drive point identification information included in the received signal. Here, changing the coefficient to be used means switching the coefficient to be used from a set of a plurality of previously estimated coefficients, re-estimating the coefficient, and changing the coefficient to be used to the estimated coefficient. Including that.

For example, in an actual satellite communication system, the application of modulation methods such as VCM (Variable Coding Modulation) and ACM (Adaptive Coding and Modulation) is being considered. Since the backoff value that can make the best use of the line varies depending on the modulation method used, it is required to drive the amplifier at a different drive point, that is, a different drive point for each modulation method. When driving at different driving points, it is necessary to replace the coefficient to be compensated. Therefore, the coefficients held by the intermodulation component estimation units 105 and 115 can be replaced for each drive point. In this case, the drive point identification information may be an identifier of the modulation method added to the communication frame. The wireless receiving device 100 can improve the receiving performance at various drive points by adopting a configuration in which the coefficients are replaced or re-estimated based on the identifier of the modulation method.

In addition, in satellite communication systems, the application of TDMA (Time Division Multiplexing Access) by beam hopping is also being considered. In the satellite communication downlink, it is conceivable that the ground station communicates with various satellites depending on the satellite constellation configuration. It is also conceivable that the satellite is equipped with a plurality of amplifiers. In this case, the drive point identification information may be backoff information, an amplifier unique identifier, or the like. This allows the ground station to control the coefficient re-estimation and replacement timing. By configuring the system so that the scramble pattern is changed for each satellite or each amplifier for transmission, the wireless receiver 100 can identify the fluctuation of the amplifier and control the signal processing parameter estimation.

FIG. 5 is a flowchart for explaining the operation of the wireless receiving device 100 shown in FIG. In the following description, a system composed of an antenna 101, an RF circuit unit 102, a non-linear equalization unit 103, an intermodulation component estimation unit 105, a rigid determination unit 106, an intermodulation component canceling unit 107, and an FEC unit 108. The processing of is described. Although omitted below, the system is composed of an antenna 111, an RF circuit unit 112, a non-linear equalization unit 113, an intermodulation component estimation unit 115, a rigid determination unit 116, an intermodulation component canceling unit 117, and an FEC unit 118. The same applies to the processing. The process of replacing the code for the functional part with the same name is executed in parallel with the process described below.

When the antenna 101 of the wireless receiving device 100 receives the signal from the transmitting device, the RF circuit unit 102 converts the received signal into a baseband signal tuned to the carrier (step S101).

The non-linear equalization unit 103 performs a non-linear equalization process to remove the distortion component of its own carrier from the baseband signal acquired from the RF circuit unit 102 (step S102).

The intermodulation component estimation unit 105 determines whether or not the cancellation process of the intermodulation component has been executed (step S103).

When the cancellation process of the intermodulation component has not been executed (step S103: No), the reference signal generation unit 104 generates a reference signal for each carrier (step S104). The intermodulation component estimation unit 105 estimates the intermodulation component based on the reference signal (step S105). The intermodulation component canceling unit 107 cancels the intermodulation component by subtracting the estimated value of the intermodulation component from the received signal output by the nonlinear equalization unit 103 (step S106).

The hardness determination unit 106 executes the hardness determination process based on the signal output by the intermodulation component canceling unit 107 (step S107). After the execution of step S107, the signal output by the intermodulation component canceling unit 107 is fed back to the nonlinear equalization unit 103, and the process is repeated from step S102.

When the cancellation processing of the intermodulation component has been executed (step S103: Yes), the processing of steps S104 to S107 is omitted, and the rigid determination unit 106 is based on the signal output by the intermodulation component canceling unit 107. The hardness determination process is executed (step S108). When the signal output by the intermodulation component canceling unit 107 is fed back to the non-linear equalization unit 103, the non-linear equalization unit 103 performs the same non-linear equalization processing as the previous time by using the fed back signal, and self. Removes carrier distortion components. At this time, the intermodulation component canceling unit 107 outputs the signal output by the non-linear equalizing unit 103 as it is without canceling the intermodulation component.

The FEC unit 108 performs error correction / decoding processing (step S109). The processes of steps S101 to S109 are executed when the antenna 101 receives a signal.

As described above, according to the wireless receiving device 100 according to the first embodiment of the present invention, it is a distortion component generated between carriers when the transmitting device amplifies a signal including a plurality of carriers with a single amplifier. The intermodulation component can be estimated and the estimated intermodulation component can be canceled from the received signal. Therefore, it is possible to compensate for the intermodulation distortion while suppressing an increase in the circuit scale in the transmission device. Therefore, the reception quality can be improved. Further, when applied to satellite communication, the degree of freedom in designing a common amplification system is improved.

In the DPD that suppresses intermodulation distortion in the transmission device, a circuit that feeds back the transmission signal is required, which not only increases the circuit scale of the signal processing circuit, but also meets the two requirements of removing spurious and reducing distortion of the transmission spectrum. On the other hand, it is necessary to perform appropriate signal processing. However, spurious removal and strain reduction are often difficult to achieve at the same time. In addition, it is difficult to realize it because a tracking mechanism is required for fluctuations such as deterioration over time. According to the wireless receiving device 100, it is possible to compensate for the intermodulation distortion on the receiving side, so that the above-mentioned problems can be solved. Even when DPD is performed, distortion may occur on the receiving side, the transmission line, and the like, so that the signal processing on the receiving side is not always lightened.

In FIG. 1, different RF circuit units 102 and 112 are provided for each carrier, but this embodiment is not limited to such an example. For example, if the wireless receiver 100 has a configuration in which a baseband signal tuned to two carriers can be obtained, the same RF circuit is provided using a common antenna to convert the signal into an intermediate frequency band, and then two signals are obtained. A DDC (Digital to Digital Converter) that converts signals with different frequencies may be provided to obtain two baseband signals.

Embodiment 2.
FIG. 6 is a diagram showing a functional configuration of the wireless receiver 100A according to the second embodiment of the present invention. The wireless receiver 100A includes antennas 101 and 111, RF circuit units 102 and 112, pre-filters 303 and 313, reference signal generation units 304, intermodulation component estimation units 305 and 315, and intermodulation component canceling units. It has 307,317 and FEC units 308,318.

The wireless receiving device 100A has pre-filters 303 and 313 instead of the non-linear equalizing units 103 and 113 of the wireless receiving device 100. The prefix filters 303 and 313 sample the signal by interpolation processing of the received signal. The prefix filters 303 and 313 use a known timing synchronization method to control the filter coefficient based on the delay amount obtained from the timing detection result. The prefix filters 303 and 313 may be provided with a term in which a coefficient is given to the product of the absolute value squared of the received signal for nonlinear equalization and the received signal, and the nonlinear compensation may be performed. The pre-filters 303 and 313 output the sampled signal to the intermodulation component estimation units 305 and 315 and the intermodulation component canceling units 307 and 317, respectively.

As shown in FIG. 4, reference signal # 1, reference signal # 2, received signal, and equalization filter coefficient are input to the intermodulation component estimation units 105 and 115. On the other hand, the outputs of the pre-filters 303 and 313 are input to the intermodulation component estimation units 305 and 315 instead of the received signals, and the equalization filter coefficient is not input. The intermodulation component estimation units 305 and 315 use the outputs of the pre-filters 303 and 313 instead of the received signals to perform intermodulation component estimation processing in the same procedure as the intermodulation component estimation units 105 and 115. However, the intermodulation component estimation units 305 and 315 perform the same correction as the nonlinear equalization units 103 and 113 for the result of the linear combination described in the intermodulation component estimation units 105 and 115. Is omitted and the result of the linear combination is output as the final intermodulation component estimate.

The reference signal generation unit 304 generates a reference signal using the FEC output results obtained by the FEC units 308 and 318. In the FEC output, error detection is possible depending on the error correction detection code used, and the FEC units 308 and 318 output the determination result to the reference signal generation unit 304 only when no error is detected. You may. By adopting such a configuration, it is possible to suppress the occurrence of an error in the estimation result when an error occurs. Reference signal generating unit 304 re-modulates the signal from the FEC results, based on the result, as in the first embodiment, the two carrier components S _L, the reference signal to estimate the respective S _H # 1 and Generate reference signal # 2.

The intermodulation component canceling units 307 and 317 output to the FEC units 308 and 318 the values obtained by subtracting the estimation results of the intermodulation components output by the intermodulation component estimation units 305 and 315 from the outputs of the forward filters 303 and 313. To do.

FIG. 7 is a flowchart for explaining the operation of the wireless receiving device 100A shown in FIG. In the following description, processing of a system including an antenna 101, an RF circuit unit 102, a forward filter 303, an intermodulation component estimation unit 305, an intermodulation component canceling unit 307, and an FEC unit 308 will be described. Although omitted below, the same applies to the processing of the system composed of the antenna 111, the RF circuit unit 112, the forward filter 313, the intermodulation component estimation unit 315, the intermodulation component canceling unit 317, and the FEC unit 318. .. The process of replacing the code for the functional part with the same name is executed in parallel with the process described below.

When the antenna 101 of the wireless receiving device 100A receives the signal from the transmitting device, the RF circuit unit 102 converts the received signal into a baseband signal tuned to the carrier (step S201).

The pre-filter 303 performs interpolation processing and samples the received signal (step S202).

The reference signal generation unit 304 generates a reference signal for each carrier (step S203). The intermodulation component estimation unit 305 estimates the intermodulation component based on the reference signal (step S204). The intermodulation component canceling unit 307 cancels the intermodulation component by subtracting the estimated value of the intermodulation component from the received signal output by the pre-filter 303 (step S205).

The FEC unit 308 performs error correction / decoding processing (step S206). The processes of steps S201 to S206 are executed when the antenna 101 receives a signal.

As described above, according to the wireless receiving device 100A according to the second embodiment of the present invention, even in the wireless receiving device 100A which does not have the nonlinear distortion compensation function by appropriate equalization, transmission is performed as in the first embodiment. When the device amplifies a signal containing a plurality of carriers with a single amplifier, the intermodulation component which is a distortion component generated between the carriers can be estimated, and the estimated intermodulation component can be canceled from the received signal. Therefore, it is possible to compensate for the intermodulation distortion while suppressing an increase in the circuit scale in the transmission device.

FIG. 8 is a diagram showing a configuration example when the wireless receivers 100 and 100A according to the first and second embodiments of the present invention are realized by hardware. The functions of the wireless reception devices 100 and 100A can be realized by using the reception data generation circuit 401, the processing circuit 402, and the reception result storage device 403.

The received data generation circuit 401 can execute the processing of the antennas 101 and 111 and the RF circuit units 102 and 112.

The processing circuit 402 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), an LSI (Large Scale Integration), or a combination thereof. It is a thing. The processing circuit 402 includes a non-linear equalization unit 103, 113, a reference signal generation unit 104, 304, an intermodulation component estimation unit 105, 115, 305, 315, a rigid determination unit 106, 116, an intermodulation component canceling unit 107, 117, The processes of 307, 317, FEC units 108, 118, 308, 318 and the pre-filters 303, 313 can be executed. The reception result storage device 403 is a storage device that stores the demodulation result.

Although an example is shown above, the division of functions of the received data generation circuit 401 and the processing circuit 402 may be changed as necessary.

FIG. 9 is a diagram showing a configuration example in which a part of the functions of the wireless receivers 100 and 100A according to the first and second embodiments of the present invention is realized by software. The functions of the wireless receivers 100 and 100A can be realized by using the reception data generation circuit 401, the processor 404, the memory 405, and the display 406.

The processor 404 is a CPU (Central Processing Unit), and is also called a control circuit, a processing device, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.

The memory 405 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EPROM (registered trademark) (Electrically EPROM). Magnetic discs, flexible discs, optical discs, compact discs, mini discs, DVDs (Digital Versatile Disks), etc.

The processor 404 reads and executes a distortion compensation program stored in the memory 405 corresponding to the processing of each component, and executes the nonlinear equalization units 103 and 113, the reference signal generation units 104 and 304, and the intermodulation component estimation unit 105. , 115, 305, 315, rigid determination unit 106, 116, intermodulation component canceling unit 107, 117, 307, 317, FEC unit 108, 118, 308, 318 and pre-filter 303, 313. Can be done. The memory 405 is also used as a temporary memory in each process executed by the processor 404. Although an example is shown above, the division of functions of the received data generation circuit 401 and the processor 404 may be changed as necessary. The distortion compensation program may be provided via a communication path or may be provided in a state of being stored in a storage medium.

Display 406 displays the processing result. The display 406 is an LCD (Liquid Crystal Display) or the like. Although it is assumed here that the wireless receiving devices 100 and 100A have the display 406, the first and second embodiments are not limited to such an example. For example, the display 406 may be provided in a device other than the wireless receivers 100 and 100A that operate by acquiring the demodulation result.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

11 header, 12 payload, 13 pilot, 100, 100A wireless receiver, 101, 111 antenna, 102, 112 RF circuit section, 103, 113 non-linear equalization section, 104, 304 reference signal generation section, 105, 115, 305, 315 Intermodulation component estimation unit, 106,116 Hard judgment unit, 107,117,307,317 Intermodulation component cancellation unit, 108,118,308,318 FEC unit, 201 Known signal holding unit, 202 Intermodulation basic component generation unit , 203 Received signal storage unit, 204 Linear coupling coefficient generator, 205 Replica generator, 303,313 Prefix filter, 401 Received data generation circuit, 402 Processing circuit, 403 Reception result storage device, 404 processor, 405 memory, 406 display ..

Claims (10)

A wireless receiver that receives a signal containing an intermodulation component, which is a distortion component generated between the carriers when the transmitting device amplifies a signal containing a plurality of carriers with a single amplifier.
A reference signal generator that generates a reference signal that estimates the signal components of each of the plurality of carriers,
An intermodulation component estimation unit that estimates the intermodulation component included in the received signal based on the plurality of reference signals, and an intermodulation component estimation unit.
An intermodulation component canceling unit that subtracts the estimated intermodulation component from the received signal,
A wireless receiver characterized by having. The first aspect of the present invention is that the intermodulation component canceling unit subtracts the estimated intermodulation component from the received signal after suppressing the distortion component generated in the carrier by performing a non-linear equalization process. The wireless receiver described. The reference signal generation unit is a plurality of carriers based on a known sequence, a tentative determination signal generated in a receiver that receives each carrier, a rigid determination result of the received signal, or an output of an error correction decoder. The wireless receiver according to claim 1 or 2, wherein the reference signal of the above is generated. The claim is characterized in that the intermodulation component estimation unit represents an estimation result of the intermodulation component by a linear combination using a plurality of intermodulation basic components and respective coefficients of the plurality of intermodulation basic components. The wireless receiving device according to any one of 1 to 3. The intermodulation component estimation unit performs a correlation calculation between each of the plurality of intermodulation basic components and the received signal, and a minimum between the received signal using each of the plurality of intermodulation basic components as an explanatory variable. The wireless receiver according to claim 4, wherein the coefficient is determined by using a sequential algorithm based on the square method or the least squares method. The received signal includes drive point identification information for identifying the drive point of the amplifier.
The radio reception according to claim 4 or 5, wherein the intermodulation component estimation unit changes the coefficient used for estimating the intermodulation component based on the received drive point identification information. apparatus. The claim is characterized in that the intermodulation component estimation unit changes the coefficient to be used by switching the coefficient to be used from the pre-estimated coefficients or by performing re-estimation processing of the coefficient. 6. The wireless receiving device according to 6. A control circuit that controls a wireless receiving device that receives a signal containing an intermodulation component, which is a distortion component generated between carriers when a transmitting device amplifies a signal containing a plurality of carriers with a single amplifier.
A step of generating a reference signal for each of the plurality of carriers, and
A step of estimating the intermodulation component included in the received signal based on the plurality of the reference signals, and
A step of subtracting the estimated intermodulation component from the received signal,
A control circuit characterized by having a wireless receiver carry out the above. In a storage medium that stores a program that controls a wireless receiver that receives a signal containing an intermodulation component, which is a distortion component generated between the carriers when the transmitting device amplifies a signal containing a plurality of carriers with a single amplifier. , The program
A step of generating a reference signal in which the signal components of each of the plurality of carriers are estimated, and
A step of estimating the intermodulation component included in the received signal based on the plurality of the reference signals, and
A step of subtracting the estimated intermodulation component from the received signal,
A storage medium, characterized in that a wireless receiving device is used to perform the above. A wireless communication method executed by a wireless receiving device that receives a signal containing an intermodulation component, which is a distortion component generated between the carriers when the transmitting device amplifies a signal containing a plurality of carriers with a single amplifier.
A step of generating a reference signal in which the signal components of each of the plurality of carriers are estimated, and
A step of estimating the intermodulation component included in the received signal based on the plurality of the reference signals, and
A step of subtracting the estimated intermodulation component from the received signal,
A wireless communication method comprising.

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