CN107026673A - The analog domain interference cancellation method and device of a kind of digital assistant - Google Patents
The analog domain interference cancellation method and device of a kind of digital assistant Download PDFInfo
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Abstract
The invention discloses the analog domain interference cancellation method and device of a kind of digital assistant, this method includes signal transmitting, signal feedback, signal reconstruction and signal and receives four steps, using non-linear extraction unit estimation nonlinear parameter vector in signal feedback step, reconstructing digital transmission signal is calculated using non-linear reconstruction unit in signal reconstruction step；The device includes signal launching circuit, signal feedback loop, signal reconstruction loop and signal receiving circuit.This method can effectively suppress to launch the Nonlinear perturbations that radio-frequency channel is introduced, non-linear estimations and parameter adjustment can be easily carried out in numeric field, it can easily estimate to launch the multipath channel between radio-frequency channel and receiving RF channel in numeric field, and adjusting parameter, it is more conducive to expand to other application scene, robustness is stronger.
Description
Technical Field
The present invention relates to the field of radio, and more particularly, to a method and apparatus for digitally assisted cancellation of interference in the analog domain.
Background
The current wireless communication system adopts a time division duplex or frequency division duplex method to carry out bidirectional communication. The time division duplex system uses the same frequency but different time slots to transmit data, thereby isolating the interference between an uplink and a downlink. Frequency division duplex systems use the same time slot but different frequencies to transmit data, thereby isolating interference between the uplink and downlink. The two duplex methods respectively sacrifice time resources and frequency resources in the process of isolating uplink and downlink, so that the frequency spectrum utilization rate is low.
The demand of the modern society for wireless data service is increasing day by day, and the degree of crowding of the spatial wireless channel is more and more prominent, which compels people to continuously seek new methods to improve the utilization rate of frequency spectrum resources and the anti-interference performance of equipment. If the wireless communication device uses the same time, same frequency full duplex technology to transmit and receive wireless signals, it will undoubtedly double the spectral efficiency of the wireless communication link.
However, simultaneous co-frequency full duplex operates by simultaneously transmitting and receiving rf signals at the same carrier frequency. Therefore, the transmitted signal will also propagate to the receiving end, thereby forming a strong self-interference signal, blocking the receiver analog-to-digital converter, resulting in that the receiver cannot receive the useful signal, the self-interference strength is much stronger than the strength of the signal received by the receiving end from the far-end wireless communication device, thereby seriously affecting the receiving of the signal transmitted by the far-end wireless device by the receiving end. In general, this will reduce the sensitivity of the receiving end, increase the error rate, and cause the communication performance to be reduced; in severe cases, the receiving channel of the receiving end is blocked, which results in complete loss of receiving function and even burning of the front end of the receiver.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method and a device for canceling digital-assisted analog domain interference, the method can effectively inhibit nonlinear interference introduced by a transmitting radio frequency channel, can conveniently perform nonlinear estimation and parameter adjustment in a digital domain, can conveniently estimate a multipath channel between the transmitting radio frequency channel and a receiving radio frequency channel in the digital domain, adjust parameters, is more beneficial to expanding to other application scenes, and has stronger robustness.
The purpose of the invention is realized by the following technical scheme: a digital auxiliary analog domain interference cancellation method comprises four steps of signal transmission, signal feedback, signal reconstruction and signal reception;
the signal transmitting step comprises the following substeps:
s11: the signal to be transmitted is processed by a transmitting baseband unit to obtain a digital signal x [ n ], wherein n represents discrete time;
s12: the digital signal x [ n ] is sent to a first digital-to-analog converter, a nonlinear extraction unit and a nonlinear reconstruction unit respectively;
s13: the digital signal x [ n ] sent to the first digital-to-analog converter is converted into a radio frequency signal x (t) through a transmitting radio frequency channel, wherein t represents continuous time; the radio frequency signals x (t) are respectively sent to the antenna unit and the feedback radio frequency channel;
s14: the radio frequency signal x (t) sent into the antenna unit is transmitted out through the antenna unit;
the signal feedback step comprises the following substeps:
s21: the feedback RF channel receives the RF signal x (t) from the transmit RF channel for down-conversionAfter filtering, the signal is sent to a first analog-to-digital converter to be converted into a digital feedback signal xfb[n]；
S22, sending the digital feedback signal y n into the nonlinear extraction unit, and carrying out time synchronization and power normalization operation with the output digital emission signal x n of the emission baseband unit to obtain the digital feedback signal y n which is synchronous with x n in time and equal (or very similar) to x n in power;
s23, modeling the nonlinear characteristics of the transmitting radio frequency channel by using a memory polynomial model containing even-order terms, wherein the memory polynomial model containing the even-order terms can be expressed as:
where K represents the maximum nonlinear order of the memory polynomial model, Q represents the maximum memory depth of the memory polynomial model, wkqRepresenting the nonlinear parameter of the memory polynomial model at the qth memory depth of the k order;
s24, when two sides of the equation of the formula (1) are simultaneously selected from N groups of data for arrangement, the matrix expression of the formula (1) can be obtained:
Y＝XW (2)
whereinRepresenting a digital feedback signal y n]N is a column vector consisting of 0,1, …, N-1, and symbol T represents a transposition operation; x represents a digital reflection signal X n]A matrix of dimensions N × KQ is composed, defined as:
X＝[X0,X1,…,XN-1]T
wherein
W represents a parameter vector composed of nonlinear parameters, defined as:
W＝[w00,…,wkq,…,w(K-1)(Q-1)]T
s25, solving the equation (2) and calculating the estimation result of the nonlinear parameter vector W
S26 the nonlinear extraction unit estimates the nonlinear parameter vector WSending the data into a nonlinear reconstruction unit;
the signal reconstruction step comprises the following substeps:
s31: the nonlinear reconstruction unit receives the digital signal x [ n ] output by the transmitting baseband unit]And the estimation result output by the nonlinear extraction unit, and the signal x [ n ] is subjected to equation (3)]Processing to obtain a reconstructed digital transmission signal xtx[n]Expressed as:
reconstruction of a digital transmission signal xtx[n]Sending the data to a channel reconstruction unit;
s32: channel reconstruction unit acquiring signal xtx[n]And the output digital received signal r [ n ] of the second analog-to-digital converter]Estimating a multipath channel response h (t) between a transmitting radio frequency channel and a receiving radio frequency channel; discrete estimation result h [ n ] of multipath channel response h (t)]Convolution operation is carried out with the reconstructed digital transmitting signal to obtain a digital reconstructed signal xtc[n]As an output signal of the channel reconstruction unit;
s33: digital reconstructed signal xtc[n]Sending the signal to a second digital-to-analog converter for conversion into an analog reconstruction signal xtc(t)；
S34: analog reconstruction signal xtc(t) sending the interference suppression unit;
the signal receiving step comprises the following substeps:
s41: the receiving signal s (t) from the far end enters the interference suppression unit through the antenna unit;
s42: the interference suppression unit receives the receiving signal s (t), and then subtracts the receiving signal s (t) from the radio frequency reconstruction signal z (t) to eliminate the self-interference signal and obtain a low-frequency-band analog receiving signal;
s44: the analog receiving signal is sent to a second analog-to-digital conversion module to obtain a receiving digital signal sn; the received digital signal s [ n ] is processed by a receiving baseband unit to obtain a desired received signal.
Calculating an estimation result of a non-linear parameter vector WThe method of (1) includes a least squares method and an iterative algorithm.
A digital auxiliary analog domain interference cancellation device comprises a signal transmitting loop, a signal feedback loop, a signal reconstruction loop and a signal receiving loop;
the signal transmitting loop comprises a transmitting baseband unit, a first digital-to-analog converter, a transmitting radio frequency channel and an antenna unit, the transmitting baseband unit processes digital signals of signals to be transmitted and transmits the signals to the first digital-to-analog converter, the nonlinear extraction unit and the nonlinear reconstruction unit, and the digital signals entering the first digital-to-analog converter are converted into radio frequency signals through the transmitting radio frequency channel and transmitted out through the antenna unit;
the signal feedback loop comprises feedbackThe feedback radio frequency channel receives a radio frequency signal output by the transmitting radio frequency channel, the radio frequency signal is transmitted to the first analog-to-digital converter after down conversion and filtering and is converted into a digital feedback signal which is transmitted to the nonlinear extraction unit, the nonlinear extraction unit processes the digital feedback signal and a digital signal output by the transmitting baseband unit to obtain an estimation result of a nonlinear parameter vector WAnd sent to a nonlinear reconstruction unit;
the signal reconstruction loop comprises a nonlinear reconstruction unit, a channel reconstruction unit, a second digital-to-analog converter and a reconstruction radio frequency channel, the nonlinear reconstruction unit receives the digital signal output by the transmitting baseband unit and the estimation result output by the nonlinear extraction unit to calculate and reconstruct a digital transmitting signal and sends the digital transmitting signal to the channel reconstruction unit, the channel reconstruction unit obtains the reconstructed digital transmitting signal and the digital receiving signal output by the second analog-to-digital converter to calculate a digital reconstruction signal and inputs the digital reconstruction signal into the second digital-to-analog converter, and the second digital-to-analog converter converts the digital reconstruction signal into an analog reconstruction signal and transmits the analog reconstruction signal to the interference suppression unit;
the signal receiving loop comprises an antenna unit, an interference suppression unit, a second analog-to-digital converter and a receiving baseband unit, wherein a receiving signal received by the antenna unit is transmitted to the interference suppression unit, the interference suppression unit sends an obtained low-frequency-band analog receiving signal to a second analog-to-digital conversion module after interference suppression is completed, the second analog-to-digital conversion module converts the obtained receiving digital signal and transmits the obtained receiving digital signal to the receiving baseband unit, and the receiving baseband unit processes the obtained receiving digital signal to obtain an expected receiving signal.
The antenna unit comprises a circulator and a receiving and transmitting antenna, and a radio frequency signal output by the transmitting radio frequency channel is sent to the port 1 of the circulator, then is transmitted to the port 2 of the circulator for output, and is sent to the receiving and transmitting antenna for transmitting; the receiving signal received by the transmitting-receiving antenna enters the port No. 2 of the circulator and then is output to the interference suppression unit from the port No. 3.
The antenna unit comprises a transmitting antenna and a receiving antenna which are mutually independent, and a radio-frequency signal output by a transmitting radio-frequency channel is transmitted to the transmitting antenna for transmitting; the reception signal received by the reception antenna is output to the interference suppression unit.
The interference suppression unit comprises a reconstructed radio frequency signal, a radio frequency combiner and a received radio frequency channel, the second digital-to-analog converter outputs an analog reconstructed signal to be transmitted to the reconstructed radio frequency channel, the reconstructed radio frequency channel is processed to obtain a radio frequency reconstructed signal and input the radio frequency reconstructed signal to the radio frequency combiner, the received signal received by the antenna unit is transmitted to the radio frequency combiner, the radio frequency combiner subtracts the received signal from the radio frequency reconstructed signal to eliminate a self-interference signal and outputs the self-interference signal, and the low-frequency-band analog received signal is obtained after the received radio frequency channel is received and is transmitted to the second analog-to-.
The interference suppression unit comprises a combiner and a receiving radio frequency channel, wherein the receiving signals received by the antenna unit are transmitted to the receiving radio frequency channel, the receiving radio frequency channel is processed to obtain low-frequency-band analog receiving signals and then transmits the low-frequency-band analog receiving signals to the combiner, and the combiner subtracts the analog receiving signals from analog reconstruction signals output by the second digital-to-analog converter to eliminate self-interference signals and then outputs the self-interference signals to the second analog-to-digital conversion module.
The invention has the beneficial effects that: the invention provides a digital-assisted radio frequency interference cancellation method and a digital-assisted radio frequency interference cancellation device, which can effectively inhibit nonlinear interference introduced by a transmitting radio frequency channel, can conveniently perform nonlinear estimation and parameter adjustment in a digital domain, can conveniently estimate a multipath channel between the transmitting radio frequency channel and a receiving radio frequency channel in the digital domain, adjust parameters, are more beneficial to expanding to other application scenes, and have stronger robustness.
Drawings
FIG. 1 is a block diagram of a digitally assisted analog domain self-interference cancellation apparatus;
FIG. 2 is a first embodiment of a digitally assisted analog domain self-interference cancellation apparatus;
FIG. 3 is a second embodiment of a digitally assisted analog domain self-interference cancellation apparatus;
FIG. 4 is a third embodiment of a digitally assisted analog domain self-interference cancellation apparatus;
fig. 5 is a fourth embodiment of a digitally assisted analog domain self-interference cancellation apparatus.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.
A digital auxiliary analog domain interference cancellation method comprises four steps of signal transmission, signal feedback, signal reconstruction and signal reception;
the signal transmitting step comprises the following substeps:
s11: the signal to be transmitted is processed by a transmitting baseband unit to obtain a digital signal x [ n ], wherein n represents discrete time;
s12: the digital signal x [ n ] is sent to a first digital-to-analog converter, a nonlinear extraction unit and a nonlinear reconstruction unit respectively;
s13: the digital signal x [ n ] sent to the first digital-to-analog converter is converted into a radio frequency signal x (t) through a transmitting radio frequency channel, wherein t represents continuous time; the radio frequency signals x (t) are respectively sent to the antenna unit and the feedback radio frequency channel;
s14: the radio frequency signal x (t) sent into the antenna unit is transmitted out through the antenna unit;
the signal feedback step comprises the following substeps:
s21: the feedback radio frequency channel receives a radio frequency signal x (t) from the transmitting radio frequency channel, performs down conversion and filtering, and then sends the radio frequency signal x (t) to the first analog-to-digital converter to be converted into a digital inverseFeed signal xfb[n]；
S22, sending the digital feedback signal y n into the nonlinear extraction unit, and carrying out time synchronization and power normalization operation with the output digital emission signal x n of the emission baseband unit to obtain the digital feedback signal y n which is synchronous with x n in time and equal (or very similar) to x n in power;
s23, modeling the nonlinear characteristics of the transmitting radio frequency channel by using a memory polynomial model containing even-order terms, wherein the memory polynomial model containing the even-order terms can be expressed as:
where K represents the maximum nonlinear order of the memory polynomial model, Q represents the maximum memory depth of the memory polynomial model, wkqRepresenting the nonlinear parameter of the memory polynomial model at the qth memory depth of the k order;
s24, when two sides of the equation of the formula (1) are simultaneously selected from N groups of data for arrangement, the matrix expression of the formula (1) can be obtained:
Y＝XW (4)
whereinRepresenting a digital feedback signal y n]N is a column vector consisting of 0,1, …, N-1, and symbol T represents a transposition operation; x represents a digital reflection signal X n]A matrix of dimensions N × KQ is composed, defined as:
X＝[X0,X1,…,XN-1]T
wherein
W represents a parameter vector composed of nonlinear parameters, defined as:
W＝[w00,…,wkq,…,w(K-1)(Q-1)]T
s25, solving the equation (2) and calculating the estimation result of the nonlinear parameter vector WThe calculation method comprises a least square method and an iterative algorithm, and the least square solution of the parameter vector W can be obtained by adopting the least square method as follows:
wherein
Calculating the estimation result of the nonlinear parameter vector W by adopting an iterative algorithmThe method comprises
Wherein k (n) is the gain vector at the current time, and the expression is
Xi (n) is the prior estimation error of the current moment and is expressed as
In the formula (6), the reaction mixture is,
T(n)＝P(n-1)Xn(8)
wherein,
lambda is a forgetting factor of the iterative least square RLS algorithm, the value of lambda is a numerical value of 0-1, different values influence the convergence speed of the algorithm, and the lambda is selected according to actual needs.
Setting in the initialization phase of the recursive algorithmAnd P (0) ═ I, setting a priori estimated error threshold value in the iterative process of the algorithm to be compared with ξ (n), and completing the parameter when the error ξ (n) is less than the threshold valueAnd (4) calculating. In this way, the power amplifier fitting model achieves different accuracies;
s26 the nonlinear extraction unit estimates the nonlinear parameter vector WSending the data into a nonlinear reconstruction unit;
the signal reconstruction step comprises the following substeps:
s31: the nonlinear reconstruction unit receives the digital signal x [ n ] output by the transmitting baseband unit]And the estimation result output by the nonlinear extraction unit, and the signal x [ n ] is subjected to equation (3)]Processing to obtain a reconstructed digital transmission signal xtx[n]Expressed as:
reconstruction of a digital transmission signal xtx[n]Sending the data to a channel reconstruction unit;
s32: channel reconstruction unit acquiring signal xtx[n]And the output digital received signal r [ n ] of the second analog-to-digital converter]Estimating a multipath channel response h (t) between a transmitting radio frequency channel and a receiving radio frequency channel; discrete estimation result h [ n ] of multipath channel response h (t)]Convolution operation is carried out with the reconstructed digital transmitting signal to obtain a digital reconstructed signal xtc[n]As an output signal of the channel reconstruction unit;
s33: digital reconstructed signal xtc[n]Sending the signal to a second digital-to-analog converter for conversion into an analog reconstruction signal xtc(t)；
S34: analog reconstruction signal xtc(t) sending the interference suppression unit;
the signal receiving step comprises the following substeps:
s41: the receiving signal s (t) from the far end enters the interference suppression unit through the antenna unit;
s42: the interference suppression unit receives the receiving signal s (t), and then subtracts the receiving signal s (t) from the radio frequency reconstruction signal z (t) to eliminate the self-interference signal and obtain a low-frequency-band analog receiving signal;
s44: the analog receiving signal is sent to a second analog-to-digital conversion module to obtain a receiving digital signal sn; the received digital signal s [ n ] is processed by a receiving baseband unit to obtain a desired received signal.
When the antenna unit is a circulator and a receiving and transmitting antenna, the radio-frequency signal x (t) is sent into the port 1 of the circulator, then is transmitted to the port 2 of the circulator for output, and is sent to the receiving and transmitting antenna for transmission; the received signal r (t) from the far end enters the No. 2 port of the circulator through the transceiving antenna and then is output from the No. 3 port to the interference suppressionAnd (5) manufacturing a unit. Due to the limited isolation of the circulator, the radio frequency signal x (t) leaks to the port No. 3 and enters the receiving radio frequency channel to form a self-interference signal. At this time, the second digital-to-analog converter outputs an analog reconstruction signal xtc(t) sending the radio frequency reconstruction channel to obtain a radio frequency reconstruction signal z (t), sending the radio frequency reconstruction signal z (t) into a radio frequency combiner, subtracting the radio frequency reconstruction signal z (t) after the radio frequency combiner receives the receiving signal r (t) to eliminate a self-interference signal, and sending the output of the radio frequency combiner to a second analog-to-digital conversion module after the radio frequency combiner receives the radio frequency channel to obtain a low-frequency-band analog receiving signal.
When the output signal power of the antenna unit is within the bearing range of the power sensitive device in the receiving radio frequency channel and the receiving radio frequency channel can not introduce interference (such as nonlinear distortion of a low noise amplifier) to the signal additionally, the interference suppression unit only comprises a combiner and the receiving radio frequency channel, the receiving signal received by the antenna unit is transmitted to the receiving radio frequency channel, the receiving radio frequency channel is processed to obtain a low-frequency-band analog receiving signal, the low-frequency-band analog receiving signal is sent to the combiner, and the combiner subtracts the analog receiving signal from the analog reconstruction signal output by the second digital-to-analog converter to eliminate the self-interference signal and outputs the self-interference signal to the second analog-to-digital conversion module.
As shown in fig. 1, a digitally-assisted analog domain interference cancellation apparatus includes a signal transmitting loop, a signal feedback loop, a signal reconstruction loop, and a signal receiving loop;
the signal transmitting loop comprises a transmitting baseband unit, a first digital-to-analog converter, a transmitting radio frequency channel and an antenna unit, the transmitting baseband unit processes digital signals of signals to be transmitted and transmits the signals to the first digital-to-analog converter, the nonlinear extraction unit and the nonlinear reconstruction unit, and the digital signals entering the first digital-to-analog converter are converted into radio frequency signals through the transmitting radio frequency channel and transmitted out through the antenna unit;
the signal feedback loop comprises a feedback radio frequency channel, a first analog-to-digital converter and a nonlinear extraction unit, wherein the feedback radio frequency channel receives the radio frequency signal output by the transmitting radio frequency channel, and the radio frequency signal is transmitted to a second analog-to-digital converter after down-conversion and filteringAn analog-to-digital converter converts the digital feedback signal into a nonlinear extraction unit, the nonlinear extraction unit processes the digital feedback signal and the digital signal output by the transmitting baseband unit to obtain an estimation result of a nonlinear parameter vector WAnd sent to a nonlinear reconstruction unit;
the signal reconstruction loop comprises a nonlinear reconstruction unit, a channel reconstruction unit, a second digital-to-analog converter and a reconstruction radio frequency channel, the nonlinear reconstruction unit receives the digital signal output by the transmitting baseband unit and the estimation result output by the nonlinear extraction unit to calculate and reconstruct a digital transmitting signal and sends the digital transmitting signal to the channel reconstruction unit, the channel reconstruction unit obtains the reconstructed digital transmitting signal and the digital receiving signal output by the second analog-to-digital converter to calculate a digital reconstruction signal and inputs the digital reconstruction signal into the second digital-to-analog converter, and the second digital-to-analog converter converts the digital reconstruction signal into an analog reconstruction signal and transmits the analog reconstruction signal to the interference suppression unit;
the signal receiving loop comprises an antenna unit, an interference suppression unit, a second analog-to-digital converter and a receiving baseband unit, wherein a receiving signal received by the antenna unit is transmitted to the interference suppression unit, the interference suppression unit sends an obtained low-frequency-band analog receiving signal to a second analog-to-digital conversion module after interference suppression is completed, the second analog-to-digital conversion module converts the obtained receiving digital signal and transmits the obtained receiving digital signal to the receiving baseband unit, and the receiving baseband unit processes the obtained receiving digital signal to obtain an expected receiving signal.
As shown in fig. 2, in an embodiment of the present invention, the antenna unit includes a circulator and a transceiver antenna, and the radio frequency signal output by the transmitting radio frequency channel is sent to port No. 1 of the circulator, then is transmitted to port No. 2 of the circulator for output, and is sent to the transceiver antenna for transmission; the receiving signal received by the transmitting-receiving antenna enters the port No. 2 of the circulator and then is output to the interference suppression unit from the port No. 3.
As shown in fig. 3, in another embodiment of the present invention, the antenna unit includes a transmitting antenna and a receiving antenna that are independent from each other, and the rf signal output by the transmitting rf channel is transmitted to the transmitting antenna for transmission; the reception signal received by the reception antenna is output to the interference suppression unit.
As shown in fig. 4, in the third embodiment of the present invention, the interference suppression unit includes a reconstructed rf signal, a rf combiner, and a received rf channel, the second digital-to-analog converter outputs an analog reconstructed signal to the reconstructed rf channel, the reconstructed rf channel is processed to obtain a rf reconstructed signal and inputs the rf reconstructed signal to the rf combiner, the antenna unit receives a received signal and transmits the received signal to the rf combiner, the rf combiner subtracts the received signal from the rf reconstructed signal to eliminate a self-interference signal and outputs the self-interference signal, and the received rf channel receives a low-frequency analog received signal and transmits the low-frequency analog received signal to the second analog-to-digital conversion module.
As shown in fig. 5, in the fourth embodiment of the present invention, the interference suppression unit includes a combiner and a receiving radio frequency channel, the receiving signal received by the antenna unit is transmitted to the receiving radio frequency channel, the receiving radio frequency channel processes the received signal to obtain a low-frequency analog receiving signal, and the low-frequency analog receiving signal is transmitted to the combiner, and the combiner subtracts the analog receiving signal from the analog reconstruction signal output by the second digital-to-analog converter to eliminate the self-interference signal, and outputs the self-interference signal to the second analog-to-digital conversion module.
Claims (7)
1. A digital-assisted analog domain interference cancellation method is characterized in that: the method comprises four steps of signal transmission, signal feedback, signal reconstruction and signal reception;
the signal transmitting step comprises the following substeps:
s11: the signal to be transmitted is processed by a transmitting baseband unit to obtain a digital signal x [ n ], wherein n represents discrete time;
s12: the digital signal x [ n ] is sent to a first digital-to-analog converter, a nonlinear extraction unit and a nonlinear reconstruction unit respectively;
s13: the digital signal x [ n ] sent to the first digital-to-analog converter is converted into a radio frequency signal x (t) through a transmitting radio frequency channel, wherein t represents continuous time; the radio frequency signals x (t) are respectively sent to the antenna unit and the feedback radio frequency channel;
s14: the radio frequency signal x (t) sent into the antenna unit is transmitted out through the antenna unit;
the signal feedback step comprises the following substeps:
s21: the feedback RF channel receives the RF signal x (t) from the transmitting RF channel, down-converts, filters, and converts the RF signal x into a digital feedback signal xfb[n]；
S22, sending the digital feedback signal y n into the nonlinear extraction unit, and carrying out time synchronization and power normalization operation with the output digital emission signal x n of the emission baseband unit to obtain the digital feedback signal y n which is synchronous with x n in time and equal (or very similar) to x n in power;
s23, modeling the nonlinear characteristics of the transmitting radio frequency channel by using a memory polynomial model containing even-order terms, wherein the memory polynomial model containing the even-order terms can be expressed as:
where K represents the maximum nonlinear order of the memory polynomial model, Q represents the maximum memory depth of the memory polynomial model, wkqRepresenting the nonlinear parameter of the memory polynomial model at the qth memory depth of the k order;
s24, when two sides of the equation of the formula (1) are simultaneously selected from N groups of data for arrangement, the matrix expression of the formula (1) can be obtained:
Y＝XW (2)
whereinRepresenting a digital feedback signal y n]N is a column vector consisting of 0,1, …, N-1, and symbol T represents a transposition operation; x represents a digital reflection signal X n]A matrix of dimensions N × KQ is composed, defined as:
X＝[X0,X1,…,XN-1]T
wherein
W represents a parameter vector composed of nonlinear parameters, defined as:
W＝[w00,…,wkq,…,w(K-1)(Q-1)]T
s25, solving the equation (2) and calculating the estimation result of the nonlinear parameter vector W
S26 the nonlinear extraction unit estimates the nonlinear parameter vector WSending the data into a nonlinear reconstruction unit;
the signal reconstruction step comprises the following substeps:
s31: the nonlinear reconstruction unit receives the digital signal x [ n ] output by the transmitting baseband unit]And the estimation result output by the nonlinear extraction unit, and the signal x [ n ] is subjected to equation (3)]Processing to obtain a reconstructed digital transmission signal xtx[n]Expressed as:
reconstruction of a digital transmission signal xtx[n]Sending the data to a channel reconstruction unit;
s32: channel reconstruction unit acquiring signal xtx[n]And the output digital received signal r [ n ] of the second analog-to-digital converter]Estimating a multipath channel response h (t) between a transmitting radio frequency channel and a receiving radio frequency channel; departure of multipath channel response h (t)The variance estimation result h [ n ]]Convolution operation is carried out with the reconstructed digital transmitting signal to obtain a digital reconstructed signal xtc[n]As an output signal of the channel reconstruction unit;
s33: digital reconstructed signal xtc[n]Sending the signal to a second digital-to-analog converter for conversion into an analog reconstruction signal xtc(t)；
S34: analog reconstruction signal xtc(t) sending the interference suppression unit;
the signal receiving step comprises the following substeps:
s41: the receiving signal s (t) from the far end enters the interference suppression unit through the antenna unit;
s42: the interference suppression unit receives the receiving signal s (t), and then subtracts the receiving signal s (t) from the radio frequency reconstruction signal z (t) to eliminate the self-interference signal and obtain a low-frequency-band analog receiving signal;
s44: the analog receiving signal is sent to a second analog-to-digital conversion module to obtain a receiving digital signal sn; the received digital signal s [ n ] is processed by a receiving baseband unit to obtain a desired received signal.
2. The method of claim 1, wherein the method further comprises: calculating an estimation result of a non-linear parameter vector WThe method of (1) includes a least squares method and an iterative algorithm.
3. An apparatus for use in a digitally-assisted analog domain interference cancellation method according to any one of claims 1-2, wherein: the system comprises a signal transmitting loop, a signal feedback loop, a signal reconstruction loop and a signal receiving loop;
the signal transmitting loop comprises a transmitting baseband unit, a first digital-to-analog converter, a transmitting radio frequency channel and an antenna unit, the transmitting baseband unit processes digital signals of signals to be transmitted and transmits the signals to the first digital-to-analog converter, the nonlinear extraction unit and the nonlinear reconstruction unit, and the digital signals entering the first digital-to-analog converter are converted into radio frequency signals through the transmitting radio frequency channel and transmitted out through the antenna unit;
the signal feedback loop comprises a feedback radio frequency channel, a first analog-to-digital converter and a nonlinear extraction unit, the feedback radio frequency channel receives a radio frequency signal output by a transmitting radio frequency channel, the radio frequency signal is transmitted to the first analog-to-digital converter after down-conversion and filtering and then is converted into a digital feedback signal, the digital feedback signal is transmitted to the nonlinear extraction unit, the nonlinear extraction unit processes the digital feedback signal and a digital signal output by the transmitting baseband unit, and an estimation result of a nonlinear parameter vector W is obtainedAnd sent to a nonlinear reconstruction unit;
the signal reconstruction loop comprises a nonlinear reconstruction unit, a channel reconstruction unit, a second digital-to-analog converter and a reconstruction radio frequency channel, the nonlinear reconstruction unit receives the digital signal output by the transmitting baseband unit and the estimation result output by the nonlinear extraction unit to calculate and reconstruct a digital transmitting signal and sends the digital transmitting signal to the channel reconstruction unit, the channel reconstruction unit obtains the reconstructed digital transmitting signal and the digital receiving signal output by the second analog-to-digital converter to calculate a digital reconstruction signal and inputs the digital reconstruction signal into the second digital-to-analog converter, and the second digital-to-analog converter converts the digital reconstruction signal into an analog reconstruction signal and transmits the analog reconstruction signal to the interference suppression unit;
the signal receiving loop comprises an antenna unit, an interference suppression unit, a second analog-to-digital converter and a receiving baseband unit, wherein a receiving signal received by the antenna unit is transmitted to the interference suppression unit, the interference suppression unit sends an obtained low-frequency-band analog receiving signal to a second analog-to-digital conversion module after interference suppression is completed, the second analog-to-digital conversion module converts the obtained receiving digital signal and transmits the obtained receiving digital signal to the receiving baseband unit, and the receiving baseband unit processes the obtained receiving digital signal to obtain an expected receiving signal.
4. A digitally-assisted analog domain interference cancellation arrangement according to claim 3, wherein: the antenna unit comprises a circulator and a receiving and transmitting antenna, and a radio frequency signal output by the transmitting radio frequency channel is sent to the port 1 of the circulator, then is transmitted to the port 2 of the circulator for output, and is sent to the receiving and transmitting antenna for transmitting; the receiving signal received by the transmitting-receiving antenna enters the port No. 2 of the circulator and then is output to the interference suppression unit from the port No. 3.
5. A digitally-assisted analog domain interference cancellation arrangement according to claim 3, wherein: the antenna unit comprises a transmitting antenna and a receiving antenna which are mutually independent, and a radio-frequency signal output by a transmitting radio-frequency channel is transmitted to the transmitting antenna for transmitting; the reception signal received by the reception antenna is output to the interference suppression unit.
6. A digitally-assisted analog domain interference cancellation arrangement according to claim 3, wherein: the interference suppression unit comprises a reconstructed radio frequency signal, a radio frequency combiner and a received radio frequency channel, the second digital-to-analog converter outputs an analog reconstructed signal to be transmitted to the reconstructed radio frequency channel, the reconstructed radio frequency channel is processed to obtain a radio frequency reconstructed signal and input the radio frequency reconstructed signal to the radio frequency combiner, the received signal received by the antenna unit is transmitted to the radio frequency combiner, the radio frequency combiner subtracts the received signal from the radio frequency reconstructed signal to eliminate a self-interference signal and outputs the self-interference signal, and the low-frequency-band analog received signal is obtained after the received radio frequency channel is received and is transmitted to the second analog-to-.
7. A digitally-assisted analog domain interference cancellation arrangement according to claim 3, wherein: the interference suppression unit comprises a combiner and a receiving radio frequency channel, wherein the receiving signals received by the antenna unit are transmitted to the receiving radio frequency channel, the receiving radio frequency channel is processed to obtain low-frequency-band analog receiving signals and then transmits the low-frequency-band analog receiving signals to the combiner, and the combiner subtracts the analog receiving signals from analog reconstruction signals output by the second digital-to-analog converter to eliminate self-interference signals and then outputs the self-interference signals to the second analog-to-digital conversion module.
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