CN111131103B - Multimode signal interference elimination method and system - Google Patents
Multimode signal interference elimination method and system Download PDFInfo
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Abstract
The invention relates to a multimode signal interference elimination method and a multimode signal interference elimination system, wherein the method comprises the following steps: identifying a signal system of a multimode signal in a current period and carrying out corresponding gain processing on the multimode signal according to the signal system; if the signal systems of the multimode signals are narrow-band modulation systems, the gain processing is to attenuate the gain of the multimode signals by a first attenuation value; if the signal system of the multimode signal comprises a narrowband modulation system and a broadband modulation system, the gain processing is to attenuate the gain of the multimode signal by a second attenuation value; if the signal system of the multimode signal is a broadband modulation system, the gain processing is not to adjust the gain of the multimode signal; and carrying out self-adaptive filtering processing on the gain-processed multimode signal to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period. The invention can support the self-excitation signal interference elimination of multi-system signals.
Description
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a method and a system for eliminating interference of multimode signals.
Background
The self-excitation phenomenon is that the gain of the wireless repeater is large, and the distance between the receiving antenna and the transmitting antenna is short, so that the transmitting signal is coupled, received and amplified again, the wireless repeater cannot work normally, and the power amplifier can be burnt down in serious conditions. The interference elimination function is to generate an anti-phase signal of the self-excitation interference signal by using an interference elimination algorithm, so as to eliminate the self-excitation interference signal to ensure that the equipment does not generate self-excitation. At present, repeaters supporting the self-excitation cancellation function are more and more popular in the market, due to the limitation of the spatial position when repeater equipment is installed, the distance between two antennas is not far enough, the isolation is not enough, and self-excitation is easily caused, but no equipment capable of supporting the self-excitation cancellation function of mixed-mode signals exists in the market.
The prior art can reduce the gain of the equipment when the isolation is less than or equal to the system gain so as to avoid the self-excitation phenomenon.
Patent with application number cn201310159621.x discloses an LTE-ICS interference self-cancellation system and method, but the scheme is only for a single LTE signal, and only discloses one system, and does not relate to a multi-mode system. In practical use, the base station generally transmits multi-mode mixed signals simultaneously, including GSM, WCDMA, LTE, NB-IoT and the like, so that a technical scheme supporting a multimode signal self-excitation cancellation function is required.
Disclosure of Invention
The present invention is directed to overcoming at least one of the above-mentioned drawbacks of the prior art, and providing a method and a system for multi-mode signal interference cancellation, which can support free-running signal interference cancellation of multi-mode signals.
The technical scheme adopted by the invention is as follows:
a multimode signal interference elimination method can be applied to a signal transmission system, identifies the signal system of the multimode signal in the current period and carries out corresponding gain processing on the multimode signal according to the signal system;
if the signal systems of the multimode signals are narrow-band modulation systems, the gain processing is to attenuate the gain of the multimode signals by a first attenuation value;
if the signal system of the multimode signal comprises a narrowband modulation system and a broadband modulation system, the gain processing is to attenuate the gain of the multimode signal by a second attenuation value;
if the signal system of the multimode signal is a broadband modulation system, the gain processing is not to adjust the gain of the multimode signal;
and carrying out self-adaptive filtering processing on the gain-processed multimode signal to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period.
When the signal systems of the multimode signals are all broadband modulation systems, before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, the interference cancellation of the broadband signals can be realized without processing the gain of the multimode signals. When the signal systems of the multimode signals are both narrow-band modulation systems or both narrow-band modulation systems and broadband modulation systems, the gain of the multimode signals is attenuated before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, so that the problem of signal overflow of the interference signals in the interference cancellation process caused by output overshoot of the narrow-band signals can be solved, and interference cancellation of the narrow-band signals is realized. According to different signal systems of the multimode signals, different gain processing is carried out before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, so that the interference cancellation method can support the signals of the multimode systems.
Further, before performing corresponding gain processing on the multimode signal, frequency offset processing and/or phase offset processing is performed on the multimode signal.
After the multimode signal entering the signal transmission system is superposed with the interference cancellation signal, an interference signal which cannot be completely cancelled and is caused by a self-excitation phenomenon possibly exists, before the multimode signal is subjected to corresponding gain processing, the multimode signal is subjected to frequency offset processing and/or phase offset processing, so that the multimode signal and the interference signal can be decoupled, the correlation between the multimode signal and the interference signal is weakened, the accuracy of adaptive filtering processing can be improved, and the interference cancellation capability is improved.
Further, before the gain-processed multimode signal is subjected to adaptive filtering processing, delay adjustment processing is performed on the gain-processed multimode signal.
Before the multi-mode signal after the gain processing is subjected to the adaptive filtering processing, the multi-mode signal after the gain processing is subjected to the delay adjustment processing, so that the correlation between an interference elimination signal generated by the adaptive filter and an interference signal can be ensured.
Further, after performing corresponding gain processing on the multimode signal, if the gain processing performed on the multimode signal is to attenuate the gain of the multimode signal, the gain of the signal transmission system is adjusted according to the gain processing, so that the gain of the signal transmission system is kept unchanged.
After the gain attenuation is performed on the multimode signal, the output gain of the signal transmission system needs to be increased according to the attenuation processing performed on the gain, so that the sum of the gain attenuation and the gain increase is 0, and the output gain of the signal transmission system is kept unchanged.
Further, before the frequency offset processing is carried out on the multimode signal, the out-of-band interference signal in the multimode signal is filtered.
The out-of-band (baseband) interference signal comprises an out-of-band signal of a multi-mode signal and/or an out-of-band spurious signal generated by adaptive filtering processing, the out-of-band interference signal is suppressed, and the influence of other interference signals on a signal transmission system and the self-excitation interference elimination capability can be reduced.
A multimode signal interference elimination system is applied to a signal transmission system and comprises a gain processing module and an adaptive filtering module, wherein the gain processing module is used for identifying the signal system of a multimode signal in the current period and carrying out corresponding gain processing on the multimode signal according to the signal system, when the signal systems are all narrow-band modulation systems, the gain of the multimode signal is attenuated by a first attenuation value, when the signal systems of the multimode signal comprise both the narrow-band modulation systems and the broadband modulation systems, the gain of the multimode signal is attenuated by a second attenuation value, and when the signal systems of the multimode signal are all the broadband modulation systems, the gain processing is not to adjust the gain of the multimode signal;
the adaptive filtering module is used for performing adaptive filtering processing on the multimode signal subjected to gain processing by the gain processing module to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period.
When the signal systems of the multimode signals are all broadband modulation systems, the gain processing module can realize the interference elimination of the broadband signals without processing the gain of the multimode signals before the adaptive filtering module performs adaptive filtering processing on the multimode signals to generate interference cancellation signals. When the signal systems of the multimode signals are both narrow-band modulation systems or both narrow-band modulation systems and broadband modulation systems, the gain processing module attenuates the gain of the multimode signals before the adaptive filtering module performs adaptive filtering processing on the multimode signals to generate interference cancellation signals, so that the problem of signal overflow of the interference signals in the interference cancellation process due to output overshoot of the narrow-band signals can be avoided, and interference cancellation of the narrow-band signals is realized. According to different signal systems of the multimode signals, the gain processing module performs different gain processing before the adaptive filtering module performs adaptive filtering processing on the multimode signals to generate interference cancellation signals, so that the interference cancellation method can support the signals of the multimode systems.
Further, the multi-mode signal interference cancellation system further includes a signal offset module, where the signal offset module is configured to perform frequency offset processing and/or phase offset processing on the multi-mode signal before the gain processing module performs gain processing on the multi-mode signal.
After the multimode signal entering the signal transmission system is superposed with the interference cancellation signal, an interference signal which cannot be completely cancelled and is caused by a self-excitation phenomenon possibly exists, before the gain processing module carries out corresponding gain processing on the multimode signal, the frequency offset processing and/or the phase offset processing are carried out on the multimode signal through the signal offset module, so that the multimode signal and the interference signal can be decoupled, the correlation between the multimode signal and the interference signal is weakened, the accuracy of the adaptive filtering processing carried out by the adaptive filtering module can be improved, and the interference cancellation capability is improved.
Furthermore, the multi-mode signal interference cancellation system further includes a delay processing module, where the delay processing module is configured to perform delay adjustment processing on a delay existing in the multi-mode signal after the gain processing module performs gain processing on the multi-mode signal.
Before the adaptive filtering module performs adaptive filtering processing on the gain-processed multimode signal, the delay processing module performs delay adjustment processing on the gain-processed multimode signal, so that the correlation between an interference elimination signal generated by the adaptive filter and an interference signal can be ensured.
Further, the multi-mode signal interference cancellation system further includes a gain balancing module, where the gain balancing module is configured to, after performing corresponding gain processing on the multi-mode signal, adjust the gain of the signal transmission system according to the gain processing if the gain processing performed on the multi-mode signal is to attenuate the gain of the multi-mode signal, so as to keep the gain of the signal transmission system unchanged.
After the gain processing module performs gain attenuation on the multimode signal, the gain balancing module is required to increase the output gain of the signal transmission system according to the attenuation processing performed on the gain, so that the sum of the gain attenuation and the gain increase is 0, and the output gain of the signal transmission system is kept unchanged.
Further, the multi-mode signal interference cancellation system further includes a filter, where the filter is configured to filter an out-of-band interference signal in the multi-mode signal before performing frequency offset processing on the multi-mode signal.
The out-of-band (baseband) interference signal comprises an out-of-band signal of a multi-mode signal and/or an out-of-band spurious signal generated by adaptive filtering processing, and the out-of-band interference signal is suppressed through a filter, so that the influence of other interference signals on a signal transmission system and self-excitation interference elimination capability can be reduced.
Compared with the prior art, the invention has the beneficial effects that: the invention not only can enable the self-excitation interference elimination to support signals of various systems, but also improves the self-excitation interference elimination capability.
Drawings
Fig. 1 is a schematic diagram of a multimode interference signal cancellation method according to an embodiment of the invention.
FIG. 2 is a diagram of a digital repeater to which the multimode interference signal cancellation method is applied according to an embodiment of the present invention.
FIG. 3 is a diagram of a digital processing module of a digital repeater according to an embodiment of the present invention.
Fig. 4 is a diagram illustrating a multi-mode interference signal cancellation system according to an embodiment of the invention.
Detailed Description
The drawings are only for purposes of illustration and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The embodiment provides a multimode signal interference elimination method, which can be applied to a signal transmission system, and is used for identifying the signal system of a multimode signal in the current period and carrying out corresponding gain processing on the multimode signal according to the signal system;
if the signal systems of the multimode signals are narrow-band modulation systems, gain processing is to attenuate the gain of the multimode signals by a first attenuation value;
if the signal system of the multimode signal comprises both a narrowband modulation system and a broadband modulation system, gain processing is to attenuate the gain of the multimode signal by a second attenuation value;
if the signal systems of the multimode signals are all broadband modulation systems, the gain processing is to adjust the gain of the multimode signals;
and performing adaptive filtering processing on the gain-processed multimode signal to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period.
Specifically, fig. 1 is a schematic diagram illustrating a multimode signal interference cancellation method. In the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are mixed together and enter a signal transmission system, at the moment, the mixed signal P1(i) + P2(i) is superposed with the interference cancellation signal-P2 ' (i-1) obtained in the ith-1 period, the superposed multimode signal is output as P1(i) + P2(i) -P2 ' (i-1), self-excitation interference cancellation in the ith period can be realized to a certain extent, wherein the interference cancellation capability of the multimode signal P2(i) -P2 ' (i-1) is reflected.
Under the same total power, the peak value of the narrow-band signal is higher than that of the wide-band signal, so that the interference elimination algorithm is not converged in the self-adaptive filtering process, and the interference elimination signal overflows, so that the signal peak value can be reduced through gain attenuation. According to the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1), the multimode signal P1(i) + P2(i) -P2' (i-1) is subjected to corresponding gain processing: if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all narrow-band modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is attenuated by a first attenuation value; if the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1) comprises a narrow-band modulation system and a wide-band modulation system, attenuating the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) by a second attenuation value; if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all broadband modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is not adjusted.
After the multimode signal P1(i) + P2(i) -P2 '(i-1) is subjected to the corresponding gain processing, adaptive filtering processing is carried out to obtain an interference cancellation signal-P2' (i). The interference cancellation signal-P2' (i) is superimposed to the mixed signal P1(i +1) + P2(i +1) mixed by the multimode signal P1(i +1) and the interference signal P2(i +1) entering the signal transmission system in the i +1 th cycle, and the cancellation of the free-running interference signal in the i +1 th cycle is continuously realized.
When the signal systems of the multimode signals are all broadband modulation systems, before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, the interference cancellation of the broadband signals can be realized without processing the gain of the multimode signals. When the signal systems of the multimode signals are both narrow-band modulation systems or both narrow-band modulation systems and broadband modulation systems, the gain of the multimode signals is attenuated before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, so that the problem of signal overflow of the interference signals in the interference cancellation process caused by output overshoot of the narrow-band signals can be solved, and interference cancellation of the narrow-band signals is realized. According to different signal systems of the multimode signals, different gain processing is carried out before the multimode signals are subjected to adaptive filtering processing to generate interference cancellation signals, so that the interference cancellation method can support the signals of the multimode systems.
Preferably, the first attenuation value may be 5dB to 7dB, and the second attenuation value may be 2dB to 4 dB.
In one embodiment, the multi-mode signal is frequency offset processed and/or phase offset processed before being subjected to corresponding gain processing.
After the multimode signal entering the signal transmission system is superposed with the interference cancellation signal, an interference signal which cannot be completely cancelled and is caused by a self-excitation phenomenon possibly exists, before the multimode signal is subjected to corresponding gain processing, the multimode signal is subjected to frequency offset processing and/or phase offset processing, so that the multimode signal and the interference signal can be decoupled, the correlation between the multimode signal and the interference signal is weakened, the accuracy of adaptive filtering processing can be improved, and the interference cancellation capability is improved.
When frequency offset processing is carried out on the multimode signal, the frequency offset can be set to be about 5Hz, and the frequency offset setting can meet the decoupling of the multimode signal and an interference signal and the requirement of frequency error of the multimode signal in the standard (the highest requirement is that the frequency error is lower than 0.01 ppm).
Moreover, in the process of gain processing, when the signal system of the multimode signal includes both the narrowband modulation system and the wideband modulation system, the peak value of the narrowband signal is reduced, and the peak value of the wideband signal is also reduced, so that the interference elimination capability of the wideband signal is weakened, and the defect of reducing the interference elimination capability of the wideband signal can be compensated to a certain extent through frequency offset processing.
In one embodiment, the delay adjustment process is performed on the gain-processed multimode signal before the adaptive filtering process is performed on the gain-processed multimode signal.
Before the multi-mode signal after the gain processing is subjected to the adaptive filtering processing, the multi-mode signal after the gain processing is subjected to the delay adjustment processing, so that the correlation between an interference elimination signal generated by the adaptive filter and an interference signal can be ensured. The delay adjustment value may be the sum of the adaptive filter delay and the gain processing delay, and the value is taken as the optimal median value of the cancellation window.
In one embodiment, after performing the corresponding gain processing on the multimode signal, if the gain processing on the multimode signal is to attenuate the gain of the multimode signal, the gain of the signal transmission system is adjusted according to the gain processing, so that the gain of the signal transmission system is kept unchanged.
After the gain attenuation is performed on the multimode signal, the output gain of the signal transmission system needs to be increased according to the attenuation processing performed on the gain, so that the sum of the gain attenuation and the gain increase is 0, and the output gain of the signal transmission system is kept unchanged.
In one embodiment, out-of-band interference signals in the multi-mode signal are filtered before frequency shifting the multi-mode signal.
The out-of-band (baseband) interference signal comprises an out-of-band signal of a multi-mode signal and/or an out-of-band spurious signal generated by adaptive filtering processing, the out-of-band interference signal is suppressed, and the influence of other interference signals on a signal transmission system and the self-excitation interference elimination capability can be reduced.
The multimode signal interference elimination method can be applied to a digital wireless repeater. FIG. 2 shows a digital wireless repeater, which includes a receiving antenna T1, a duplexer T2, downlink amplifiers T31 and T32, uplink amplifiers T41 and T42, a digital processing module T5, a duplexer T6, and a user antenna T7. One end of the duplexer T2 is connected with the receiving antenna T1, and the other end is respectively connected with the downlink amplifier T31 and the uplink amplifier T42; one end of the digital processing module T5 is respectively connected with the downlink amplifier T31 and the uplink amplifier T42, and the other end is respectively connected with the downlink amplifier T32 and the uplink amplifier T41; one end of the duplexer T6 is connected to the downlink amplifier T32 and the uplink amplifier T41, respectively, and the other end is connected to the user antenna T7.
In the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are superimposed into a downlink signal P1(i) + P2(i), the downlink signal P3526 (i) is input to the duplexer T2 from the receiving antenna T1, separated from the uplink signal by the duplexer T2, enters the downlink amplifier T31 for first amplification, then enters the digital processing module T5, enters the downlink amplifier T32 for second amplification after digital processing, and finally the uplink and downlink signal are recombined and sent to the user antenna T7 through the duplexer T6.
As shown in fig. 3, the digital processing module T5 includes an analog/digital converter S101, a digital down-conversion module S102, a baseband processing module S103, a digital up-conversion module S104, and a digital/analog converter S105, which are connected in sequence.
The specific steps of entering the digital processing module for digital processing of the downlink signal P1(i) + P2(i) are as follows: in the ith period, the downlink signal P1(i) + P2(i) enters the analog/digital converter S101 to be sampled into a digital signal, the digital signal enters the digital down-conversion module S102 to be down-converted to form a baseband signal, the baseband signal enters the baseband processing module S103 to be baseband processed, the baseband signal is processed by the baseband and then enters the digital up-conversion module S104 to be a radio frequency signal, and the radio frequency signal is converted into an analog signal by the digital/analog converter S105.
As shown in fig. 1, the above multimode interference cancellation method is adopted in the baseband processing module S103 to perform interference cancellation on the baseband signal entering the baseband processing module S103, specifically: in the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are mixed and enter the baseband processing module, at this time, the mixed signal P1(i) + P2(i) is superposed with the interference cancellation signal-P2 ' (i-1) obtained in the ith-1 period, the superposed multimode signal is output as P1(i) + P2(i) -P2 ' (i-1), self-excitation interference cancellation in the ith period can be realized to a certain extent, wherein the interference cancellation capability of the multimode signal P2(i) -P2 ' (i-1) is reflected.
And filtering out-of-band interference signals by the superposed multimode signals P1(i) + P2(i) -P2' (i-1).
After the out-of-band interference signal filtering is carried out, frequency offset processing and/or phase offset processing are carried out on the multimode signal P1(i) + P2(i) -P2 '(i-1), and the correlation between the multimode signal P1(i) + P2(i) -P2' (i-1) and the residual interference signal is weakened.
After the frequency offset processing and/or the phase offset processing are/is carried out, according to the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1), the multimode signal P1(i) + P2(i) -P2' (i-1) after the offset processing is carried out with corresponding gain processing: if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all narrow-band modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is attenuated by a first attenuation value; if the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1) comprises a narrow-band modulation system and a wide-band modulation system, attenuating the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) by a second attenuation value; if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all broadband modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is not adjusted.
After the corresponding gain processing is carried out, the delay adjustment processing is carried out on the gain-processed multimode signal P1(i) + P2(i) -P2' (i-1).
After the delay adjustment processing is carried out, the multimode signal P1(i) + P2(i) -P2 '(i-1) is subjected to adaptive filtering processing to obtain an interference cancellation signal-P2' (i). The interference cancellation signal-P2' (i) is superimposed to the mixed signal P1(i +1) + P2(i +1) mixed by the multimode signal P1(i +1) and the interference signal P2(i +1) entering the signal transmission system in the i +1 th cycle, and the cancellation of the free-running interference signal in the i +1 th cycle is continuously realized.
Based on the same inventive concept as the above multimode signal interference cancellation method, in one embodiment, a multimode signal interference cancellation system is further provided, which is applied to a signal transmission system and includes a gain processing module R101 and an adaptive filtering module R102, where the gain processing module R101 is configured to identify a signal format of a multimode signal in a current period and perform corresponding gain processing on the multimode signal according to the signal format, attenuate a gain of the multimode signal by a first attenuation value when the signal formats are all narrowband modulation formats, attenuate the gain of the multimode signal by a second attenuation value when the signal formats of the multimode signal include both a narrowband modulation format and a wideband modulation format, and process the gain to not adjust the gain of the multimode signal when the signal formats of the multimode signal are all wideband modulation formats;
the adaptive filtering module R102 is configured to perform adaptive filtering on the multimode signal subjected to gain processing by the gain processing module R101 to obtain an interference cancellation signal of the multimode signal, and superimpose the interference cancellation signal on the multimode signal in the next period.
Specifically, fig. 4 is a schematic diagram of a multimode signal interference cancellation system. In the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are mixed together and enter the signal transmission system, at this time, the mixed signal P1(i) + P2(i) is superposed with the interference cancellation signal-P2 ' (i-1) obtained by the adaptive filtering module R102 in the ith-1 period, the superposed multimode signal is output as P1(i) + P2(i) -P2 ' (i-1), and the self-excitation interference signal cancellation in the ith period can be realized to a certain extent, wherein the interference cancellation capability of the signal is reflected by P2(i) -P2 ' (i-1).
The gain processing module R101 performs corresponding gain processing on the multimode signal P1(i) + P2(i) -P2 '(i-1) according to the signal system of the multimode signal P1(i) + P2(i) -P2' (i-1): if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all narrow-band modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is attenuated by a first attenuation value; if the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1) comprises a narrow-band modulation system and a wide-band modulation system, attenuating the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) by a second attenuation value; if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all broadband modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is not adjusted.
After the gain processing module R101 performs the corresponding gain processing on the multimode signal P1(i) + P2(i) -P2 '(i-1), the adaptive filtering module R102 performs adaptive filtering processing to obtain an interference cancellation signal-P2' (i). The interference cancellation signal-P2' (i) is superimposed to the mixed signal P1(i +1) + P2(i +1) mixed by the multimode signal P1(i +1) and the interference signal P2(i +1) entering the signal transmission system in the i +1 th cycle, and the cancellation of the free-running interference signal in the i +1 th cycle is continuously realized.
When the signal systems of the multimode signals are all the broadband modulation systems, the gain processing module R101 may not need to process the gain of the multimode signals before the adaptive filtering module R102 performs the adaptive filtering processing on the multimode signals to generate the interference cancellation signal, so as to achieve the interference cancellation of the broadband signals. When the signal systems of the multimode signals are both narrowband modulation systems or include both narrowband modulation systems and broadband modulation systems, the gain processing module R101 may avoid the signal overflow problem of the interference signal in the interference cancellation process due to output overshoot of the narrowband signal by attenuating the gain of the multimode signal before the adaptive filtering module R102 performs adaptive filtering processing on the multimode signal to generate the interference cancellation signal, thereby realizing interference cancellation of the narrowband signal. According to different signal systems of the multimode signals, before the adaptive filtering module R102 performs adaptive filtering processing on the multimode signals to generate interference cancellation signals, the gain processing module R101 performs different gain processing, so that the interference cancellation method can support the multimode signals.
Preferably, the first attenuation value may be 5dB to 7dB, and the second attenuation value may be 2dB to 4 dB.
In one embodiment, the multimode signal interference cancellation system further includes a signal offset module R103, where the signal offset module R103 is configured to perform frequency offset processing and/or phase offset processing on the multimode signal before the gain processing module R101 performs gain processing on the multimode signal.
After the multi-mode signal entering the signal transmission system is superposed with the interference cancellation signal, there may be an interference signal caused by a self-excitation phenomenon that cannot be completely cancelled, and before the gain processing module R101 performs corresponding gain processing on the multi-mode signal, the frequency offset processing and/or the phase offset processing are performed on the multi-mode signal by the signal offset module R103, so that the multi-mode signal and the interference signal can be decoupled, the correlation between the multi-mode signal and the interference signal is weakened, the accuracy of the adaptive filtering processing performed by the adaptive filtering module R102 can be improved, and the interference cancellation capability is improved.
When the frequency offset processing is performed on the multimode signal through the signal offset module R103, the frequency offset may be set to about 5Hz, and the frequency offset setting may not only satisfy the decoupling of the multimode signal and the interference signal, but also satisfy the requirement for the frequency error of the multimode signal in the standard (the highest requirement is that the frequency error is lower than 0.01 ppm).
In an embodiment, the multimode signal interference cancellation system further includes a delay processing module R104, where the delay processing module R104 is configured to perform delay adjustment processing on a delay existing in the multimode signal after the gain processing module R101 performs gain processing on the multimode signal.
Before the adaptive filtering module R102 performs adaptive filtering on the gain-processed multimode signal, the delay processing module R104 performs delay adjustment on the gain-processed multimode signal, so as to ensure the correlation between the interference cancellation signal generated by the adaptive filter R106 and the interference signal. The delay adjustment value may be the sum of the delay of the adaptive filter R106 and the delay of the gain processing, which is taken as the median of the cancellation window to be optimal.
In one embodiment, the multimode signal interference cancellation system further includes a gain balancing module R105, where the gain balancing module R105 is configured to, after performing corresponding gain processing on the multimode signal, adjust the gain of the signal transmission system according to the gain processing if the gain processing performed on the multimode signal is to attenuate the gain of the multimode signal, so that the gain of the signal transmission system remains unchanged.
After the gain processing module R101 performs gain attenuation on the multimode signal, the gain balancing module R105 is required to increase the output gain of the signal transmission system according to the attenuation processing performed on the gain, so that the sum of the gain attenuation and the gain increase is 0, and the output gain of the signal transmission system is kept unchanged.
In one embodiment, the multi-mode signal interference cancellation system further includes a filter R106, where the filter R106 is configured to filter out-of-band interference signals in the multi-mode signal before performing frequency offset processing on the multi-mode signal.
The out-of-band (baseband) interference signal includes an out-of-band signal of a multi-mode signal and/or an out-of-band spurious signal generated by adaptive filtering processing, and the out-of-band interference signal is suppressed through the filter R106, so that the influence of other interference signals on a signal transmission system and self-excitation interference elimination capability can be reduced.
The multimode signal interference elimination method can be applied to a digital wireless repeater. FIG. 2 shows a digital wireless repeater, which includes a receiving antenna T1, a duplexer T2, downlink amplifiers T31 and T32, uplink amplifiers T41 and T42, a digital processing module T5, a duplexer T6, and a user antenna T7. One end of the duplexer T2 is connected with the receiving antenna T1, and the other end is respectively connected with the downlink amplifier T31 and the uplink amplifier T42; one end of the digital processing module T5 is respectively connected with the downlink amplifier T31 and the uplink amplifier T42, and the other end is respectively connected with the downlink amplifier T32 and the uplink amplifier T41; one end of the duplexer T6 is connected to the downlink amplifier T32 and the uplink amplifier T41, respectively, and the other end is connected to the user antenna T7.
In the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are superimposed into a downlink signal P1(i) + P2(i), the downlink signal P3526 (i) is input to the duplexer T2 from the receiving antenna T1, separated from the uplink signal by the duplexer T2, enters the downlink amplifier T31 for first amplification, then enters the digital processing module T5, enters the downlink amplifier T32 for second amplification after digital processing, and finally the uplink and downlink signal are recombined and sent to the user antenna T7 through the duplexer T6.
As shown in fig. 3, the digital processing module T5 includes an analog/digital converter S101, a digital down-conversion module S102, a baseband processing module S103, a digital up-conversion module S104, and a digital/analog converter S105, which are connected in sequence.
The specific steps of entering the digital processing module for digital processing of the downlink signal P1(i) + P2(i) are as follows: in the ith period, the downlink signal P1(i) + P2(i) enters the analog/digital converter S101 to be sampled into a digital signal, the digital signal enters the digital down-conversion module S102 to be down-converted to form a baseband signal, the baseband signal enters the baseband processing module S103 to be baseband processed, the baseband signal is processed by the baseband and then enters the digital up-conversion module S104 to be a radio frequency signal, and the radio frequency signal is converted into an analog signal by the digital/analog converter S105.
As shown in fig. 4, the above multimode interference cancellation system is adopted in the baseband processing module S103 to perform interference cancellation on the baseband signal entering the baseband processing module S103, specifically: in the ith period, the multimode signal P1(i) and the interference signal P2(i) caused by the self-excitation phenomenon are mixed and enter the baseband processing module, at this time, the mixed signal P1(i) + P2(i) is superposed with the interference cancellation signal-P2 ' (i-1) obtained by the adaptive filtering module R102 in the ith-1 period, the superposed multimode signal is output to be P1(i) + P2(i) -P2 ' (i-1), the self-excitation interference signal cancellation in the ith period can be realized to a certain extent, wherein the interference cancellation capability of the self-excitation interference signal cancellation is reflected by P2(i) -P2 ' (i-1).
The superposed multimode signal P1(i) + P2(i) -P2' (i-1) is filtered by a filter R106 to obtain an out-of-band interference signal.
After the out-of-band interference signal is filtered by the filter R106, the signal offset module R103 performs frequency offset processing and/or phase offset processing on the multimode signal P1(i) + P2(i) -P2 '(i-1), so as to weaken the correlation between the multimode signal P1(i) + P2(i) -P2' (i-1) and the remaining interference signal.
After the frequency shift processing and/or the phase shift processing are/is performed by the signal shift module R103, the gain processing module R101 performs corresponding gain processing on the multimode signal P1(i) + P2(i) -P2 '(i-1) according to the signal format of the multimode signal P1(i) + P2(i) -P2' (i-1): if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all narrow-band modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is attenuated by a first attenuation value; if the signal system of the multimode signal P1(i) + P2(i) -P2 '(i-1) comprises a narrow-band modulation system and a wide-band modulation system, attenuating the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) by a second attenuation value; if the signal systems of the multimode signal P1(i) + P2(i) -P2 '(i-1) are all broadband modulation systems, the gain of the multimode signal P1(i) + P2(i) -P2' (i-1) is not adjusted.
After the gain processing module R101 performs the corresponding gain processing, the delay processing module R104 performs delay adjustment processing on the gain-processed multimode signal P1(i) + P2(i) -P2' (i-1).
After the delay adjustment processing is performed by the delay processing module R104, the adaptive filtering module R102 performs adaptive filtering processing on the multimode signal P1(i) + P2(i) -P2 '(i-1) to obtain an interference cancellation signal-P2' (i). The interference cancellation signal-P2' (i) is superimposed to the mixed signal P1(i +1) + P2(i +1) mixed by the multimode signal P1(i +1) and the interference signal P2(i +1) entering the signal transmission system in the i +1 th cycle, and the cancellation of the free-running interference signal in the i +1 th cycle is continuously realized.
[1] It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention claims should be included in the protection scope of the present invention claims.
Claims (10)
1. A multimode signal interference elimination method can be applied to a signal transmission system, and is characterized in that a signal system of a multimode signal in the current period is identified, and corresponding gain processing is carried out on the multimode signal according to the signal system;
if the signal systems of the multimode signals are narrow-band modulation systems, the gain processing is to attenuate the gain of the multimode signals by a first attenuation value;
if the signal system of the multimode signal comprises a narrowband modulation system and a broadband modulation system, the gain processing is to attenuate the gain of the multimode signal by a second attenuation value;
if the signal system of the multimode signal is a broadband modulation system, the gain processing is not to adjust the gain of the multimode signal;
and carrying out self-adaptive filtering processing on the gain-processed multimode signal to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period.
2. The method according to claim 1, wherein the multi-mode signal is subjected to a frequency offset process and/or a phase offset process before being subjected to a corresponding gain process.
3. The method of claim 1, wherein the delay adjustment processing is performed on the gain-processed multi-mode signal before the adaptive filtering processing is performed on the gain-processed multi-mode signal.
4. The method according to claim 1, wherein after performing the corresponding gain processing on the multi-mode signal, if the gain processing on the multi-mode signal is to attenuate the gain of the multi-mode signal, the gain of the signal transmission system is adjusted according to the gain processing, so that the gain of the signal transmission system is kept unchanged.
5. The method of claim 2, wherein out-of-band interference signals in the multi-mode signal are filtered before frequency shifting the multi-mode signal.
6. A multimode signal interference elimination system is applied to a signal transmission system and is characterized by comprising a gain processing module and an adaptive filtering module, wherein the gain processing module is used for identifying the signal system of a multimode signal in the current period and carrying out corresponding gain processing on the multimode signal according to the signal system, when the signal systems are all narrow-band modulation systems, the gain of the multimode signal is attenuated by a first attenuation value, when the signal systems of the multimode signal comprise both the narrow-band modulation systems and the broadband modulation systems, the gain of the multimode signal is attenuated by a second attenuation value, and when the signal systems of the multimode signal are all the broadband modulation systems, the gain processing is not to adjust the gain of the multimode signal;
the adaptive filtering module is used for performing adaptive filtering processing on the multimode signal subjected to gain processing by the gain processing module to obtain an interference cancellation signal of the multimode signal, and superposing the interference cancellation signal to the multimode signal of the next period.
7. The multi-mode signal interference cancellation system according to claim 6, further comprising a signal offset module configured to perform frequency offset processing and/or phase offset processing on the multi-mode signal before the gain processing module performs gain processing on the multi-mode signal.
8. The multi-mode signal interference cancellation system according to claim 6, further comprising a delay processing module, configured to perform a delay adjustment process on a delay existing in the multi-mode signal after the gain processing module performs the gain processing on the multi-mode signal.
9. The system according to claim 6, further comprising a gain balancing module, configured to, after performing corresponding gain processing on the multi-mode signal, adjust the gain of the signal transmission system according to the gain processing if the gain processing performed on the multi-mode signal is to attenuate the gain of the multi-mode signal, so as to keep the gain of the signal transmission system unchanged.
10. The multi-mode signal interference cancellation system of claim 7, further comprising a filter for filtering out-of-band interference signals in the multi-mode signal prior to frequency shifting the multi-mode signal.
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