CN109245815B - Method and system for determining transmitting signal of repeater - Google Patents

Method and system for determining transmitting signal of repeater Download PDF

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CN109245815B
CN109245815B CN201810870848.8A CN201810870848A CN109245815B CN 109245815 B CN109245815 B CN 109245815B CN 201810870848 A CN201810870848 A CN 201810870848A CN 109245815 B CN109245815 B CN 109245815B
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repeater
current sampling
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echo
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CN109245815A (en
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王雅楠
潘云
夏明华
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Sun Yat Sen University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H04B7/15564—Relay station antennae loop interference reduction
    • H04B7/15585—Relay station antennae loop interference reduction by interference cancellation

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Abstract

The invention relates to a method and a system for determining a transmitting signal of a repeater, computer equipment and a computer storage medium. The method for determining the transmitting signal of the repeater comprises the following steps: determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater; filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal; subtracting the predicted echo signal from the input signal of the repeater at the current sampling moment, and determining the transmitting signal of the repeater at the current sampling moment according to the obtained signal. The invention eliminates the coupling echo signal in the transmitting signal of the repeater, reduces the noise in the transmitting signal and effectively controls the development difficulty and the construction cost of the corresponding repeater.

Description

Method and system for determining transmitting signal of repeater
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a method and a system for determining a transmission signal of a repeater, a computer device, and a computer storage medium.
Background
In a wireless communication network, a repeater is a preferred device for providing effective coverage to weak or blind areas of a base station signal. The wireless digital co-frequency repeater is widely applied due to the flexibility of erecting stations and the low installation cost. However, the co-frequency repeater has the condition that the receiving antenna is interfered by the signal fed back by the transmitting antenna (referred to as coupling echo signal interference for short). Because the receiving and transmitting antennas work at the same frequency, the coupling echo signal can not be filtered by a common filter, and when the isolation between the transmitting antenna and the receiving antenna is insufficient, the coupling echo signal enters the repeater and can generate a self-excitation effect after being amplified for many times. If the Error Vector Magnitude (EVM) is too high, the performance of the interference cancellation algorithm is unstable, so that the convergence rate is low, channel estimation cannot be performed quickly and accurately, a self-excitation effect is caused, and finally the quality of output signals of the repeater is reduced seriously.
The traditional scheme needs to solve the problem of coupling echo signal interference by improving the isolation between the receiving and transmitting antennas, for example, the physical distance between the receiving and transmitting antennas can be increased, the radiation direction of the antennas can be controlled, a physical barrier is artificially introduced between the receiving and transmitting antennas, and the like; the scheme easily causes great development difficulty and high construction cost of the repeater.
Disclosure of Invention
Based on this, it is necessary to provide a method and a system for determining a transmission signal of a repeater, a computer device, and a computer storage medium, aiming at the technical problems that the conventional scheme easily causes the repeater to have high development difficulty and high construction cost.
A method for determining a transmission signal of a repeater comprises the following steps:
determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater;
filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal;
subtracting the predicted echo signal from the input signal of the repeater at the current sampling moment, and determining the transmitting signal of the repeater at the current sampling moment according to the obtained signal.
The method for determining the transmitted signal of the repeater can determine the reference signal of the current sampling moment according to the output signal of the repeater at the set time before the current sampling moment, and filter the reference signal through the channel estimation parameter of the external echo channel of the repeater at the current sampling moment to obtain the predicted echo signal, so that the predicted echo signal is subtracted from the input signal of the repeater at the current sampling moment to eliminate the echo signal, the transmitted signal of the repeater at the current sampling moment is determined, the coupled echo signal in the determined transmitted signal is eliminated, the noise in the transmitted signal is reduced, and the development difficulty and the construction cost of the corresponding repeater are effectively controlled.
In one embodiment, the process of determining the reference signal at the current sampling moment according to the output signal of the repeater at the set time before the current sampling moment comprises the following steps:
and performing digital processing on an output signal of the repeater at a set time before the current sampling moment, and determining a signal obtained through the digital processing as a reference signal.
The embodiment digitalizes the output signal of the repeater at the set time before the current sampling moment so as to determine the reference signal, thereby improving the convenience in the subsequent signal processing process.
In one embodiment, the process of determining the transmission signal of the repeater at the current sampling time according to the obtained signal comprises:
performing digital-to-analog conversion on the obtained signal to obtain an analog signal;
and performing up-conversion operation on the analog signal to obtain a high-frequency signal, and performing linear amplification on the high-frequency signal to determine the current transmitting signal of the repeater.
In one embodiment, after the process of obtaining the predicted echo signal by filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling time, the method further includes:
determining and updating estimation parameters according to the reference signal and the conjugate transpose of the channel estimation parameters of the echo channel outside the repeater at the current sampling moment;
and determining the channel estimation parameter of the next sampling moment of the current sampling moment according to the conjugate transpose of the updated estimation parameter.
The embodiment can correspondingly update the channel estimation parameters, and ensures the timeliness of the channel estimation parameters adopted by filtering.
As an embodiment, the determining an updated estimation parameter according to the reference signal and the conjugate transpose of the channel estimation parameter of the echo channel outside the repeater at the current sampling time includes:
substituting the reference signal and the conjugate complex number of the channel estimation parameter of the echo channel outside the repeater at the current sampling moment into an updating formula to calculate and update the estimation parameter; wherein the update formula is:
Figure BDA0001752096900000031
in the formula, ω (n) represents a complex conjugate of a channel estimation parameter of an external echo channel of the repeater at the current sampling time, ω (n +1) represents an updated estimation parameter, μ represents a step factor, s (n) represents a reference signal, e (n) represents an error signal, superscript H represents a conjugate transpose, and superscript x represents conjugate calculation.
The embodiment can accurately update the channel estimation parameters, so that the echo channel outside the repeater enters the adaptive filter to track the channel state, and the adaptive channel estimation based on the NLMS (normalized least mean square) algorithm can be realized.
In one embodiment, before the process of obtaining the predicted echo signal by filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling time, the method further includes:
determining an initial conjugate parameter of an external echo channel of the repeater according to a preset ZC sequence and an output signal of the repeater at a set time before the current sampling time, and determining an initial channel estimation parameter according to the conjugate transpose of the initial conjugate parameter.
As an embodiment, the ZC sequence is:
Figure BDA0001752096900000041
in the formula, zλ(r) denotes the r-th sequence element, N denotes the sequence length, and λ denotes the subscript of the alternative sequence;
the initial conjugation parameters are: omega0＝[ω00，…,ω0l…,ω0L]，
Wherein the content of the first and second substances,
Figure BDA0001752096900000042
l denotes the filter length, xdAnd (n-r) represents the input signal of the nth-r sampling time of the repeater, the superscript H represents the conjugate transpose, and the superscript x represents the conjugate.
In the embodiment, initial channel estimation parameters can be set according to the ZC sequence at the channel estimation initialization stage, so as to ensure smooth operation of corresponding filtering, and specifically, initial conjugate parameters of an external echo channel of a repeater can be set according to the ZC sequence at set time points or at set time intervals, so as to determine corresponding initial channel estimation parameters, thereby ensuring accuracy of channel estimation parameters used for filtering.
A transmission signal determination system of a repeater, comprising:
the first determining module is used for determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater;
the filtering module is used for filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal;
and the second determination module is used for subtracting the predicted echo signal from the input signal of the repeater at the current sampling moment, and determining the transmitting signal of the repeater at the current sampling moment according to the obtained signal.
The system for determining the transmitting signal of the repeater can determine the reference signal of the current sampling moment according to the output signal of the repeater at the set time before the current sampling moment, and filter the reference signal through the channel estimation parameter of the external echo channel of the repeater at the current sampling moment to obtain the predicted echo signal, so that the predicted echo signal is subtracted from the input signal of the repeater at the current sampling moment to eliminate the echo signal, the transmitting signal of the repeater at the current sampling moment is determined, the coupling echo signal in the determined transmitting signal is eliminated, the noise in the transmitting signal is reduced, and the development difficulty and the construction cost of the corresponding repeater are effectively controlled.
A computer device includes a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method for determining the transmission signal of a repeater provided in any of the above embodiments when executing the computer program.
A computer storage medium having a computer program stored thereon, wherein the program is executed by a processor to implement the method for determining a transmission signal of a repeater provided in any of the above embodiments.
According to the method for determining the transmitting signal of the repeater, the invention also provides computer equipment and a computer storage medium, which are used for realizing the method for determining the transmitting signal of the repeater through a program. The computer device and the computer storage medium can eliminate the coupling echo signal in the transmitting signal and reduce the noise in the transmitting signal.
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FIG. 1 is a flow chart of a method for determining a transmitted signal of a repeater according to an embodiment;
FIG. 2 is a schematic diagram of an operating principle of an on-channel repeater according to an embodiment;
FIG. 3 is a schematic diagram of a system for determining a transmission signal of a repeater according to an embodiment;
FIG. 4 is a block diagram of a computer system, according to one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
It should be noted that the terms "first \ second \ third" related to the embodiments of the present invention only distinguish similar objects, and do not represent a specific ordering for the objects, and it should be understood that "first \ second \ third" may exchange a specific order or sequence when allowed. It should be understood that the terms first, second, and third, as used herein, are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in other sequences than those illustrated or otherwise described herein.
The terms "comprises" and "comprising," and any variations thereof, of embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or modules is not limited to the listed steps or modules but may alternatively include other steps or modules not listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
Reference herein to "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
Referring to fig. 1, fig. 1 is a flowchart of a method for determining a transmission signal of a repeater according to an embodiment, including:
s10, determining the reference signal of the current sampling time according to the output signal of the repeater at the set time before the current sampling time; wherein, the set time is the external echo delay of the repeater;
in a repeater, especially in a co-frequency repeater, the distance between a transmitting antenna and a receiving antenna is short, the receiving antenna is easily interfered by an echo signal fed back by the transmitting antenna, if the transmitting and receiving antenna works at the same frequency, the co-frequency signal fed back cannot be filtered by a common filter, and at this time, an input signal (namely, a received signal of the repeater) and the echo signal are superposed together and enter the repeater to interfere the communication of the repeater. And setting a feedback channel, and acquiring an output signal of a set time before the current sampling moment through the feedback channel to determine a reference signal for eliminating an echo signal in the input signal.
S20, filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling moment to obtain a predicted echo signal;
the channel estimation parameters may be preset, for example, preset according to a specific signal sequence, or determined by performing corresponding update according to the channel estimation parameters at the previous sampling time. If the channel estimation parameters are preset, a specific signal sequence can be input into the filter, the channel estimation parameters of the current sampling moment are determined according to the specific signal sequence, and then the corresponding reference signals are filtered through the determined channel estimation parameters. The filter may further include an update formula, and after filtering the reference signal at the current sampling time, the channel estimation parameter may be updated according to the current channel estimation parameter and the update formula.
S30, subtracting the predicted echo signal from the input signal of the repeater at the current sampling time, and determining the transmitting signal of the repeater at the current sampling time according to the obtained signal.
The initial receiving signal received by the repeater is usually an analog signal, and the initial receiving signal may be sampled at a set frequency (e.g., a sampling frequency of 30.72 MHz) to obtain a corresponding sampling signal, so as to determine an input signal at a current sampling time of the repeater.
The step may specifically subtract the predicted echo signal from the input signal at the current sampling time, so as to eliminate the echo signal in the input signal, that is:
Figure BDA0001752096900000081
in the formula, yd(n) represents the transmitted signal of the repeater at sampling time n (the current sampling time), xd(n) represents the repeater's input signal at sampling time n, s (n) represents the reference signal at sampling time n,
Figure BDA0001752096900000082
representing the channel estimation parameters at the sampling instant n, and the symbol indicates the convolution.
The method for determining the transmitted signal of the repeater can determine the reference signal of the current sampling moment according to the output signal of the repeater at the set time before the current sampling moment, and filter the reference signal through the channel estimation parameter of the external echo channel of the repeater at the current sampling moment to obtain the predicted echo signal, so that the predicted echo signal is subtracted from the input signal of the repeater at the current sampling moment to eliminate the echo signal, the transmitted signal of the repeater at the current sampling moment is determined, the coupled echo signal in the determined transmitted signal is eliminated, the noise in the transmitted signal is reduced, and the development difficulty and the construction cost of the corresponding repeater are effectively controlled.
In one embodiment, the process of determining the reference signal at the current sampling moment according to the output signal of the repeater at the set time before the current sampling moment comprises the following steps:
and performing digital processing on an output signal of the repeater at a set time before the current sampling moment, and determining a signal obtained through the digital processing as a reference signal.
The setting time is the external echo delay of the repeater, namely, the reference signal is determined according to the signal output by the external echo delay of the repeater (namely, the delay of an external echo channel of the repeater) before the current sampling time. The initial output signal (transmitting signal) of the repeater is an analog signal, and the output signal of the repeater at the set time before the current sampling moment is subjected to digital processing so as to determine the reference signal, so that the convenience in the subsequent signal processing process can be improved.
In one embodiment, the process of determining the transmission signal of the repeater at the current sampling moment according to the obtained signal comprises the following steps:
performing digital-to-analog conversion on the obtained signal to obtain an analog signal;
and performing up-conversion operation on the analog signal to obtain a high-frequency signal, and performing linear amplification on the high-frequency signal to determine the current transmitting signal of the repeater.
In an embodiment, after the process of obtaining the predicted echo signal by filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling time, the method further includes:
determining and updating estimation parameters according to the reference signal and the conjugate transpose of the channel estimation parameters of the echo channel outside the repeater at the current sampling moment;
and determining the channel estimation parameter of the next sampling moment of the current sampling moment according to the conjugate complex number of the updated estimation parameter.
The embodiment can correspondingly update the channel estimation parameters, and ensures the timeliness of the channel estimation parameters adopted by filtering.
As an embodiment, the determining an updated estimation parameter according to the reference signal and the conjugate transpose of the channel estimation parameter of the echo channel outside the repeater at the current sampling time includes:
substituting the reference signal and the conjugate complex number of the channel estimation parameter of the echo channel outside the repeater at the current sampling moment into an updating formula to calculate and update the estimation parameter; wherein the update formula is:
Figure BDA0001752096900000091
wherein, ω (n) represents the conjugate complex number of the channel estimation parameter of the echo channel outside the repeater at the current sampling time, ω (n +1) represents the updating estimation parameter, μ represents the step factor, s (n) represents the reference signal, e (n) represents the error signal,
Figure BDA0001752096900000092
Figure BDA0001752096900000093
the prediction echo signal is represented, the superscript H represents the conjugate transpose, and the superscript x represents the conjugate.
The embodiment can accurately update the channel estimation parameters, so that the echo channel outside the repeater enters the adaptive filter to track the channel state, and the adaptive channel estimation based on the NLMS (normalized least mean square) algorithm can be realized.
In an embodiment, before the process of obtaining the predicted echo signal by filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling time, the method further includes:
determining an initial conjugate parameter of an external echo channel of the repeater according to a preset ZC sequence, and determining an initial channel estimation parameter according to a conjugate transpose of the initial conjugate parameter.
As an embodiment, the ZC sequence is:
Figure BDA0001752096900000101
in the formula, zλ(r) denotes the r-th sequence element, r-0, 1, …, N-1, N denotes the sequence length, and λ denotes the subscript of the alternative sequence;
the initial conjugation parameters are: omega0＝[ω00，…,ω0l…,ω0L]，
Wherein the content of the first and second substances,
Figure BDA0001752096900000102
l denotes the filter length, xd(n-r) represents the input signal of the nth-r sampling time of the repeater, the superscript H represents the conjugate transpose, and the superscript x represents the conjugate; the subscript λ of the selectable sequence may be a number greater than a sequence length N, which may be greater than a filter length L.
In the embodiment, initial channel estimation parameters can be set according to the ZC sequence at the channel estimation initialization stage, so as to ensure smooth operation of corresponding filtering, and specifically, initial conjugate parameters of an external echo channel of a repeater can be set according to the ZC sequence at set time points or at set time intervals, so as to determine corresponding initial channel estimation parameters, thereby ensuring accuracy of channel estimation parameters used for filtering.
As an embodiment, the input vector corresponding to the input signal of the repeater can be represented as:
xd(n)＝[xd(n),xd(n-1),…,xd(n-L+1)]，
the reference vector corresponding to the reference signal can be expressed as:
s(n)＝[s(n),s(n-1),…,s(n-L+1)]，
the conjugate transpose of the channel estimation parameters (channel conjugate parameters) can be expressed as:
ω(n)＝[ω0(n),…,ωl(n)…,ωL(n)]，
wherein the initial conjugation parameter ω (0) ═ ω0，
The predicted echo signal may then be:
Figure BDA0001752096900000111
the channel conjugate parameter can be updated by using the NLMS algorithm, that is, the channel estimation parameter is updated:
Figure BDA0001752096900000112
in the embodiment, the ZC-NLMS algorithm can quickly realize filter coefficient convergence and adaptively track the channel state for interference elimination. Under the TDD working mode of the co-frequency repeater, the initial conjugate parameters of an external echo channel of the repeater can be set by sending a ZC sequence to a filter at intervals, and then the corresponding initial channel estimation parameters are determined.
In an embodiment, the working schematic diagram of the co-frequency repeater can refer to fig. 2, and the method for determining the transmission signal of the repeater can be run on a Field-Programmable Gate Array (FPGA). The input signal x (t) transmits a large useful signal for the on-frequency repeater, but receives the echo signal yf(t) into the receiving antenna of the repeater station, and becomes the antenna receiving signal xr(t) of (d). Signal x entering repeaterr(t) amplifying the signal by a linear amplifier with a signal amplification factor Gr. Amplifying the signal and then carrying out down-conversion to obtain a signal xr'(t). Wherein phase noise is introduced due to the influence of the local oscillator
Figure BDA0001752096900000113
Signal xr' (t) generating a digital signal x by ADC conversiond(n) entering the FPGA. The input signal to the FPGA can be expressed as:
Figure BDA0001752096900000121
where n is the sampling index corresponding to the time parameter t, and z (n) is the base noise of the input signal. y isf(n) the transmission signal of the repeater is obtained through an external feedback channel h (n), and the feedback signal can be expressed as:
yf(n)＝yf(n-kf)*h(n) (2)
wherein the symbol denotes a convolution operation, kfRepresenting the external echo signal delay. On the other hand, the radio frequency signal of the repeater is input into the auxiliary receiving link as a reference signal after being delayed by tau. Also through GrAnd carrying out down-conversion after the magnification. The reference signal is input into the FPGA after being converted by the ADC, and the reference signal input into the FPGA at the moment is as follows:
Figure BDA0001752096900000122
wherein, k represents the time delay of the inner loop, because the time delay of the outer echo signal is not consistent with the time delay of the inner feedback loop, the time delay of the inner loop is slightly less than the time delay of the outer echo signal, and k ═ k-fK represents the delay difference of the two loops. In FPGA, it is necessary to receive signal xd(n) eliminating echo signal yf(n) obtaining a useful signal x (n). The self-adaptive channel estimation algorithm can be utilized to eliminate interference and obtain an FPGA transmitting signal (a transmitting signal of a repeater) yd(n) is:
Figure BDA0001752096900000123
wherein the content of the first and second substances,
Figure BDA0001752096900000124
which represents the channel estimation coefficients, is,
Figure BDA0001752096900000125
digital signal yd(n) through DAC (Digital to Analog Conversion), up-Conversion and linear amplifier, the transmission signal y (t) can be obtained as:
Figure BDA0001752096900000126
wherein G istIs the linear amplification factor of the transmitting end,
Figure BDA0001752096900000127
the transmitting end, the receiving end and the auxiliary receiving link share a local oscillator for transmitting end phase noise.
The performance of the transmitting signal determined by the interference elimination algorithm of the traditional co-frequency repeater is compared with the performance of the transmitting signal determined by the method for determining the transmitting signal of the repeater, and for the convenience of analysis, the signal can be normalized firstly, namely the gain G of the linear amplifier is ignoredr Gt：
In the interference elimination algorithm of the traditional co-frequency repeater, the reference signal directly selects the signal y transmitted befored(n-kf) The obtained interference-cancelled signal is:
Figure BDA0001752096900000131
to facilitate the analysis of the model, the channel estimate is assumed to be accurate, i.e.
Figure BDA0001752096900000132
And the self-adaptive filter is difficult to advance due to the fact that the phase noise is changed at a high speedAnd (4) line estimation, namely setting the adaptive filter to not estimate the phase noise. Substituting equations (1), (2) and (5) into (6), if the phase noise is small enough, using a first order Taylor expansion
Figure BDA0001752096900000133
For the feedback self-interference cancellation model (the method for determining the transmit signal of the repeater provided by the invention), the interference-cancelled signal obtained by substituting the equations (1), (2), (3) and (5) into the equation (4) is:
Figure BDA0001752096900000134
because the receiving end, the transmitting end and the auxiliary receiving link are in resonance, and the phase noise correlation of adjacent sampling points is strong, the phase noise correlation of the adjacent sampling points is strong
Figure BDA0001752096900000135
It can be seen that the feedback type phase noise self-suppression system adopted in the method for determining the transmitting signal of the repeater of the invention has a suppression effect on the influence of the phase noise.
As an embodiment, as shown in fig. 2, an adaptive filter may be set in a co-frequency repeater, and an initial conjugate parameter of an echo channel outside the repeater is set to the ZC sequence of the adaptive filter at intervals, so as to determine a corresponding initial channel estimation parameter, and then the channel estimation parameter at a subsequent sampling time is updated according to the initial channel estimation parameter and an update formula, so as to achieve fast convergence of a filter coefficient and eliminate an echo signal in an input signal.
In the FPGA, downsampling can be performed in a digital domain to select a proper signal digital domain processing frequency. When the system performs channel estimation for interference cancellation, a higher sampling frequency may cause an increase in channel estimation error. Therefore, on the premise of ensuring normal communication, the sampling frequency can be reduced as much as possible, and the lowest sampling frequencies required by different communication systems are different. A sampling frequency of 30.72MHz may be employed for LTE systems; meanwhile, in the process of carrying out digital domain down-sampling in the FPGA, the fraction delay is reduced by selecting the optimal sampling point through relevant operation.
The embodiment provides a scheme capable of effectively reducing EVM (error vector magnitude), rapidly eliminating interference and reducing channel coefficient estimation errors aiming at the problems of low convergence rate, large influence of local oscillator phase noise and large channel estimation coefficient errors of a common co-frequency repeater channel estimation algorithm. Simulation results show that the EVM specified by 3GPP is not more than 4.5 percent under the indoor channel model of single path or multipath. Therefore, the design scheme of the same-frequency repeater applicable to the TDD working mode has stronger engineering implementation significance.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a system for determining a transmission signal of a repeater according to an embodiment, including:
the first determining module is used for determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater;
the filtering module is used for filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal;
and the second determination module is used for subtracting the predicted echo signal from the input signal of the repeater at the current sampling moment, and determining the transmitting signal of the repeater at the current sampling moment according to the obtained signal.
In one embodiment, the first determination module is further configured to:
and performing digital processing on an output signal of the repeater at a set time before the current sampling moment, and determining a signal obtained through the digital processing as a reference signal.
In one embodiment, the second determination module is further configured to:
performing digital-to-analog conversion on the obtained signal to obtain an analog signal;
and performing up-conversion operation on the analog signal to obtain a high-frequency signal, and performing linear amplification on the high-frequency signal to determine the current transmitting signal of the repeater.
In one embodiment, the system for determining the transmission signal of the repeater further comprises:
a third determining module, configured to determine an updated estimation parameter according to the reference signal and a conjugate transpose of a channel estimation parameter of an external echo channel of the repeater at a current sampling time;
and a fourth determining module, configured to determine, according to the conjugate transpose of the updated estimation parameter, a channel estimation parameter at a next sampling time of the current sampling time.
As an embodiment, the fourth determining module is further configured to:
substituting the reference signal and the conjugate complex number of the channel estimation parameter of the echo channel outside the repeater at the current sampling moment into an updating formula to calculate and update the estimation parameter; wherein the update formula is:
Figure BDA0001752096900000151
in the formula, ω (n) represents a complex conjugate of a channel estimation parameter of an external echo channel of the repeater at the current sampling time, ω (n +1) represents an updated estimation parameter, μ represents a step factor, s (n) represents a reference signal, e (n) represents an error signal, superscript H represents a conjugate transpose, and superscript x represents conjugate calculation.
In one embodiment, the system for determining the transmission signal of the repeater further comprises:
and the fifth determining module is used for determining the initial conjugate parameters of the external echo channel of the repeater according to the preset ZC sequence and determining the initial channel estimation parameters according to the conjugate transpose of the initial conjugate parameters.
As an embodiment, the ZC sequence is:
Figure BDA0001752096900000152
in the formula, zλ(r) denotes the r-th sequence element, N denotes the sequence length, and λ denotes the subscript of the alternative sequence;
the initial conjugation parameters are: omega0＝[ω00，…,ω0l…,ω0L]，
Wherein the content of the first and second substances,
Figure BDA0001752096900000161
l denotes the filter length, xdAnd (n-r) represents the input signal of the nth-r sampling time of the repeater, the superscript H represents the conjugate transpose, and the superscript x represents the conjugate.
FIG. 4 is a block diagram of a computer system 1000 upon which embodiments of the present invention may be implemented. The computer system 1000 is only one example of a suitable computing environment for the invention and is not intended to suggest any limitation as to the scope of use of the invention. Neither should the computer system 1000 be interpreted as having a dependency or requirement relating to a combination of one or more components of the exemplary computer system 1000 illustrated.
The computer system 1000 shown in FIG. 4 is one example of a computer system suitable for use with the present invention. Other architectures with different subsystem configurations may also be used. Such as desktop computers, notebooks, and the like, as are well known to those of ordinary skill, may be suitable for use with some embodiments of the present invention. But are not limited to, the devices listed above.
As shown in fig. 4, the computer system 1000 includes a processor 1010, a memory 1020, and a system bus 1022. Various system components including the memory 1020 and the processor 1010 are connected to the system bus 1022. The processor 1010 is hardware for executing computer program instructions through basic arithmetic and logical operations in a computer system. Memory 1020 is a physical device used for temporarily or permanently storing computing programs or data (e.g., program state information). The system bus 1020 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus. The processor 1010 and the memory 1020 may be in data communication via a system bus 1022. Wherein memory 1020 includes Read Only Memory (ROM) or flash memory (neither shown), and Random Access Memory (RAM), which typically refers to main memory loaded with an operating system and application programs.
The computer system 1000 also includes a display interface 1030 (e.g., a graphics processing unit), a display device 1040 (e.g., a liquid crystal display), an audio interface 1050 (e.g., a sound card), and an audio device 1060 (e.g., speakers).
Computer system 1000 typically includes a storage device 1070. Storage device 1070 may be selected from a variety of computer readable media, which refers to any available media that may be accessed by computer system 1000, including both removable and non-removable media. For example, computer-readable media includes, but is not limited to, flash memory (micro SD cards), CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by computer system 1000.
Computer system 1000 also includes input device 1080 and input interface 1090 (e.g., an IO controller). A user may enter commands and information into computer system 1000 through input device 1080, such as a keyboard, a mouse, a touch-panel device on display device 1040. Input device 1080 is typically connected to system bus 1022 through an input interface 1090, but may be connected by other interface and bus structures, such as a Universal Serial Bus (USB).
Computer system 1000 may logically connect with one or more network devices in a network environment. The network device may be a personal computer, a server, a router, a tablet, or other common network node. The computer system 1000 is connected to a network device through a Local Area Network (LAN) interface 1100 or a mobile communication unit 1110. A Local Area Network (LAN) refers to a computer network formed by interconnecting within a limited area, such as a home, a school, a computer lab, or an office building using a network medium. WiFi and twisted pair wiring ethernet are the two most commonly used technologies to build local area networks. WiFi is a technology that enables computer systems 1000 to exchange data between themselves or to connect to a wireless network via radio waves. The mobile communication unit 1110 is capable of making and receiving calls over a radio communication link while moving throughout a wide geographic area. In addition to telephony, the mobile communication unit 1110 also supports internet access in a 2G, 3G or 4G cellular communication system providing mobile data services.
It should be noted that other computer systems, including more or less subsystems than computer system 1000, can also be suitable for use with the invention. As described in detail above, the computer system 1000 suitable for use with the present invention can perform the specified operations of the transmission signal determination method of a repeater. The computer system 1000 performs these operations in the form of software instructions executed by the processor 1010 in a computer-readable medium. These software instructions may be read into memory 1020 from storage device 1070 or from another device via local network interface 1100. The software instructions stored in memory 1020 cause processor 1010 to perform the method for repeater transmit signal determination described above. Furthermore, the present invention can be implemented by hardware circuits or by a combination of hardware circuits and software instructions. Thus, implementations of the invention are not limited to any specific combination of hardware circuitry and software.
The repeater transmitting signal determining system and the repeater transmitting signal determining method are in one-to-one correspondence, and the technical characteristics and the beneficial effects described in the embodiment of the repeater transmitting signal determining method are all applicable to the embodiment of the repeater transmitting signal determining system.
Based on the examples described above, there is also provided in one embodiment a computer device including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the method for determining a transmission signal of a repeater as in any one of the above embodiments.
According to the computer equipment, the echo signal in the input signal of the repeater is eliminated through the computer program running on the processor, and the development difficulty and the construction cost of the corresponding repeater are effectively controlled.
It will be understood by those skilled in the art that all or part of the processes in the method for implementing the above embodiments may be implemented by a computer program to instruct related hardware, where the program may be stored in a non-volatile computer readable storage medium, and as in the embodiments of the present invention, the program may be stored in a storage medium of a computer system and executed by at least one processor in the computer system, so as to implement the processes of the embodiments including the method for determining a transmission signal of a repeater as described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
Accordingly, in an embodiment, a computer storage medium is further provided, on which a computer program is stored, wherein the program is executed by a processor to implement the method for determining the transmission signal of the repeater in any one of the embodiments.
The computer storage medium can eliminate the coupling echo signal in the input signal of the repeater through the stored computer program, and has simple elimination process and low cost.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A method for determining a transmitting signal of a repeater is characterized in that the method is applied to an FPGA, and an input port of the FPGA comprises a receiving end and an auxiliary receiving link; the output port of the FPGA comprises a transmitting end, and the method comprises the following steps:
setting a feedback channel, and acquiring an output signal of a set time before the current sampling moment according to the feedback channel;
determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater;
filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal; the channel estimation parameters are parameters of the determined feedback channel which are preset according to a specific signal sequence or are correspondingly updated according to the channel estimation parameters at the last sampling moment;
subtracting the predicted echo signal from the input signal of the repeater at the current sampling moment, and determining the transmitting signal of the repeater at the current sampling moment according to the obtained signal, wherein the obtained transmitting signal after the interference elimination is as follows:
Figure FDA0003078016000000011
wherein the digital signal yd(n) obtaining a transmitting signal y (t) through DAC (Digital to Analog Conversion), up-Conversion and a linear amplifier;
Figure FDA0003078016000000012
wherein G istIs the linear amplification factor of the transmitting end,
Figure FDA0003078016000000013
is the phase noise at the transmitting end, x (n) the desired signal, z (n) the background noise of the input signal,
Figure FDA0003078016000000014
receiving end phase noise, kfExternal echo signal delay, y (n-k)f) Is a signal that was previously transmitted by the FPGA,
Figure FDA0003078016000000015
phase noise at the transmitting end, delay difference between the external echo signal of k' and the signal of the auxiliary receiving link,
Figure FDA0003078016000000016
the phase noise of the front transmitting end is,
Figure FDA0003078016000000017
an estimated channel;
the transmitting end is used for outputting an output signal of a set time before the current sampling moment, the receiving end is used for acquiring an input signal of the current sampling moment, and the auxiliary receiving link is used for receiving the reference signal; the transmitting end, the receiving end and the auxiliary receiving link share a local oscillator.
2. The method as claimed in claim 1, wherein the step of determining the reference signal at the current sampling time according to the output signal of the repeater set time before the current sampling time comprises:
and performing digital processing on an output signal of the repeater at a set time before the current sampling moment, and determining a signal obtained through the digital processing as a reference signal.
3. The method for determining the transmission signal of the repeater according to claim 1, wherein the process of determining the transmission signal of the repeater at the current sampling time according to the obtained signal comprises:
performing digital-to-analog conversion on the obtained signal to obtain an analog signal;
and performing up-conversion operation on the analog signal to obtain a high-frequency signal, and performing linear amplification on the high-frequency signal to determine the current transmitting signal of the repeater.
4. The method for determining the transmission signal of the repeater according to any one of claims 1 to 3, wherein after the process of filtering the reference signal by the channel estimation parameter of the echo channel outside the repeater at the current sampling time to obtain the predicted echo signal, the method further comprises:
determining and updating estimation parameters according to the reference signal and the conjugate transpose of the channel estimation parameters of the echo channel outside the repeater at the current sampling moment;
and determining the channel estimation parameter of the next sampling moment of the current sampling moment according to the conjugate transpose of the updated estimation parameter.
5. The method as claimed in claim 4, wherein the step of determining the updated estimation parameters according to the reference signal and the conjugate transpose of the channel estimation parameters of the echo channel outside the repeater at the current sampling time comprises:
substituting the reference signal and the conjugate complex number of the channel estimation parameter of the echo channel outside the repeater at the current sampling moment into an updating formula to calculate and update the estimation parameter; wherein the update formula is:
Figure FDA0003078016000000021
in the formula, ω (n) represents a complex conjugate of a channel estimation parameter of an external echo channel of the repeater at the current sampling time, ω (n +1) represents an updated estimation parameter, μ represents a step factor, s (n) represents a reference signal, e (n) represents an error signal, superscript H represents a conjugate transpose, and superscript x represents conjugate calculation.
6. The method for determining the transmission signal of the repeater according to any one of claims 1 to 3, wherein before the process of obtaining the predicted echo signal by filtering the reference signal through the channel estimation parameter of the echo channel outside the repeater at the current sampling time, the method further comprises:
determining an initial conjugate parameter of an external echo channel of the repeater according to a preset ZC sequence, and determining an initial channel estimation parameter according to a conjugate transpose of the initial conjugate parameter.
7. The method for determining the transmitted signal of a repeater according to claim 6, wherein the ZC sequence is:
Figure FDA0003078016000000031
in the formula, zλ(r) denotes the r-th sequence element, N denotes the sequence length, and λ denotes the subscript of the alternative sequence;
the initial conjugation parameters are: omega0＝[ω00，…,ω0l…,ω0L]，
Wherein the content of the first and second substances,
Figure FDA0003078016000000032
n + L-1, L denotes the filter length, xdAnd (n-r) represents the input signal of the nth-r sampling time of the repeater, the superscript H represents the conjugate transpose, and the superscript x represents the conjugate.
8. A system for determining a transmitting signal of a repeater is characterized in that the system is applied to an FPGA, and an input port of the FPGA comprises a receiving end and an auxiliary receiving link; the output port of the FPGA comprises a transmitting end, and the system comprises:
the first determining module is used for setting a feedback channel and acquiring an output signal of a set time before the current sampling moment according to the feedback channel; determining a reference signal of the current sampling moment according to an output signal of the repeater at a set time before the current sampling moment; wherein, the set time is the external echo delay of the repeater;
the filtering module is used for filtering the reference signal through a channel estimation parameter of an external echo channel of the repeater at the current sampling moment to obtain a predicted echo signal; the channel estimation parameters are parameters of the determined feedback channel which are preset according to a specific signal sequence or are correspondingly updated according to the channel estimation parameters at the last sampling moment;
a second determining module, configured to subtract the predicted echo signal from an input signal at a current sampling time of the repeater, and determine a transmitting signal of the repeater at the current sampling time according to the obtained signal, where the obtained transmitting signal after interference cancellation is:
Figure FDA0003078016000000041
wherein the digital signal yd(n) obtaining a transmitting signal y (t) through DAC (Digital to Analog Conversion), up-Conversion and a linear amplifier;
Figure FDA0003078016000000042
wherein G istIs the linear amplification factor of the transmitting end,
Figure FDA0003078016000000043
is the phase noise at the transmitting end, x (n) the desired signal, z (n) the background noise of the input signal,
Figure FDA0003078016000000044
receiving end phase noise, kfExternal echo signal delay, y (n-k)f) Is a signal that was previously transmitted by the FPGA,
Figure FDA0003078016000000045
phase noise at the transmitting end, delay difference between the external echo signal of k' and the signal of the auxiliary receiving link,
Figure FDA0003078016000000046
the phase noise of the front transmitting end is,
Figure FDA0003078016000000047
an estimated channel;
the transmitting end is used for outputting an output signal of a set time before the current sampling moment, the receiving end is used for acquiring an input signal of the current sampling moment, and the auxiliary receiving link is used for receiving the reference signal; the transmitting end, the receiving end and the auxiliary receiving link share a local oscillator.
9. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the method for determining a transmission signal of a repeater according to any one of claims 1 to 7 when executing the computer program.
10. A computer storage medium having a computer program stored thereon, wherein the program when executed by a processor implements the method for determining a transmit signal of a repeater according to any one of claims 1 to 7.
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