CN102843318A - Repeater echo cancellation device and method based on additional signals - Google Patents

Abstract

The invention discloses a repeater echo cancellation device and a repeater echo cancellation method based on additional signals. The repeater echo cancellation device comprises a receiving module, a digital down-conversion module, an additional signal module, an echo channel parameter matrix estimation module, a signal subtraction module, a signal addition module, a digital up-conversion module, a power amplifier module and a transmitting module. The repeater echo cancellation method includes a step A that a repeater is initialized; a step B that additional signals are generated; and a step C that the additional signals are added with signals received by the repeater after echo in the signals received by the repeater is cancelled, then digital up-conversion and power amplification are carried out to new signals obtained by adding the additional signals with the signals received by the repeater, and then the new signals are input to the transmitting module to be output. According to the repeater echo cancellation device and the repeater echo cancellation method based on the additional signals, the additional signals do not cause signal interference, relative error of main path attenuation coefficient is low, echo interference is effectively eliminated, data length is short in the operation process, hardware is easy to implement, and gradually convergence process of the signals does not exist after the echo cancellation is carried out to the signals. The repeater echo cancellation device and the repeater echo cancellation method based on the additional signals can be widely applied to the technical field of communication.

Description

A kind of device and method of offsetting based on the repeater echo of additional signal

Technical field

The present invention relates to the communications field, especially a kind of device and method of offsetting based on the repeater echo of additional signal.

Background technology

Existing digital high-frequency amplification station adopts following know-why to carry out echo mostly and eliminates: through signal that sends and the mixed signal that contains echo noise that receives are carried out certain processing; Estimate the characteristic parameter of echo path; The inner echo-signal that produces a simulation in the repeater deducts this signal and eliminates to realize echo from the mixed signal that receives.Since echo path normally unknown with the time change, so generally adopt sef-adapting filter to come estimated echo path.Wherein based on the sef-adapting filter of least mean-square error (Least Mean Square, be called for short LMS) principle use the most extensive.

Following brief account is technological based on the Echo Cancellation of sef-adapting filter principle:

Echo Cancellation know-why block diagram based on the sef-adapting filter principle is shown in Fig. 1.The X that transmits is fed back to inner self adaptation estimator and inner filter W simultaneously, and the error signal E that the self adaptation estimator obtains after utilizing this signal and Echo Cancellation to handle estimates outside echo channel, composes results estimated to filter W.When filter W and outside echo channel equivalence; Then transmit and be coupled to the echo-signal X' that reception antenna forms through outside echo channel and equate with the estimate echo signal Y that filter W exports; Through the additive operation link; The two is cancelled out each other, thereby makes and only comprise donor signal S (not considering the influence of interchannel noise) among the E.When the self adaptation estimator adopts the LMS algorithm, need to guarantee that E is uncorrelated with X, be provided with time delay process for this reason, can reduce or eliminate the correlation of E and X through the adjustment time-delay.

Obviously, the effect of the Echo Cancellation of above-mentioned principle depends primarily on the estimated accuracy of self adaptation estimator to outside echo channel.For the self adaptation estimator based on the LMS principle, its condition of convergence can be derived as follows.

Suppose: the outer channel impulse response is H=[h ₁h ₂H _n] ^T, the impulse response W=[w of filter W ₁w ₂... w _n] ^T, L is the exponent number of filter; Donor signal S={s (n) } _N=1,2..., echo-signal X'={x' (n) } _N=1,2..., estimated echo signal Y={y (n) } _N=1,2..., error signal E={e (n) } _N=1,2...W ⁿExpression n W value constantly, X ⁿTransmit the constantly value of X of expression n, X ⁿ=[x (n), x (n-1) ... x (n-L+1)]; Donor signal during moment n is s (n), and echo-signal is x' (n), and error signal is e (n), and X obtains estimated echo signal through filter W: y (n)=X ⁿW ⁿ

The weight coefficient renewal equation of known LMS adaptive algorithm is:

W ⁿ⁺¹=W ⁿ+2ue(n)X ⁿ （1.1）

E (n)=s (n)+x' (n)-y (n) wherein, u is the step factor of LMS adaptive algorithm

Then can obtain:

W ⁿ⁺¹=W ⁿ+2us(n)X ⁿ+2u[x'(n)-y(n)]X ⁿ （1.2）

W ⁿ⁺²=W ⁿ⁺¹+2us(n+1)X ⁿ⁺¹+2u[x'(n+1)-y(n+1)]X ⁿ⁺¹ （1.3）

W ^n+m+1=W ^n+m+2us(n+m)X ^n+m+2u[x'(n+m)-y(n+m)]X ^n+m （1.4）

1.1 ~ 1.4 formulas of conclusion can obtain:

$W^{n+m+1}=W^n+2u\underset{m=0}{\mathrm{\Σ}}s(n+m)X^{n+m}+2u\underset{m=0}{\mathrm{\Σ}}[x^{\′}(n+m)-y(n+m)]X^{n+m}---\left(1.5\right)$

Can find out, weight coefficient W is no longer upgraded, promptly algorithmic statement need make the back binomial of following formula go to zero.Wherein,

is the related operation of S and X; Can reduce or eliminate the correlation of S and X through the time delay process of adjustment among Fig. 1, thereby this is tending towards or equals zero.And all can go to zero under two kinds of situation.First kind of situation, signal X' equates that with signal Y the echo of promptly estimating equates with actual echo; Second kind of situation, signal X', signal Y are uncorrelated with signal X respectively.When the correlation that satisfies S and X requires, equate it is the sufficient and necessary condition of sef-adapting filter convergence for guaranteeing estimated echo signal with actual echo-signal, need avoid the appearance of second kind of situation.For avoiding second kind of situation to occur, should guarantee that signal X', signal Y are relevant with signal X respectively, and correlation is the bigger the better.

Can learn that from top discussion this algorithmic statement need satisfy following two requirements:

One, needs to guarantee that donor signal S is uncorrelated with the signal X that sends into the self adaptation estimator;

Two, need to guarantee that actual echo-signal X', estimated echo signal Y and the signal X that sends into the self adaptation estimator have certain correlation, and correlation is the bigger the better.

Realize the characteristic that echo cancellation system is progressively approached outer channel owing to its inner filter based on sef-adapting filter, for time varying channel, the speed speed that approaches depends on the step-length of adaptive algorithm; Step-length is long more, approaches soon more, but error is big more; Otherwise step-length is short more, and precision is high more, but velocity of approch is slower; For time variation channel faster, adaptive step and error are a pair of insurmountable contradiction.

Common adaptive algorithm has least-mean-square error algorithm (LMS), piece least-mean-square error algorithm (BLMS), normalization mean square error algorithm (NLMS) etc.These algorithms have study and follow-up control; Can satisfy the needs of optimum filtering; But it is the process of successive iteration that its weight coefficient upgrades, and its convergence rate and steady-state error are higher to the statistical property degree of dependence of input signal, the big and dynamic tracking limited ability of amount of calculation.

Through the condition of convergence based on the sef-adapting filter of LMS principle is analyzed discovery, the existing adaptive filter algorithm that utilizes the time-delay decorrelation exists from principle and can not guarantee to make multipath signal to satisfy the limitation of the condition of convergence simultaneously.For single footpath channel or when only considering the main footpath echo channel of multipath channel, the adaptive filter algorithm of existing time-delay decorrelation can come through the time-delay among adjustment Fig. 1 with good conditionsily to satisfy first requirement, but can't guarantee second requirement at outer channel.To satisfy two requirements simultaneously, need the adaptive filter algorithm of existing time-delay decorrelation be made certain improvements.When outer channel is multipath channel, send into the signal X of self adaptation estimator and which footpath echo-signal of multipath signal and satisfy second requirement, then can guarantee counteracting to this footpath echo-signal.So; Echo Cancellation technology based on this principle; Even when having only main footpath echo or main footpath echo proportion very big in the echo-signal, can obtain more satisfactory effect; When echo channel becomes when being made up of the roughly the same path of a plurality of attenuation coefficients, the Echo Cancellation effect maybe rapid deterioration.This conclusion can be explained has near the observed in actual use repeater repeater under the situation such as vehicle passes through that the phenomenon of self-excitation takes place.

Summary of the invention

In order to solve above-mentioned technical problem, the purpose of this invention is to provide high accuracy, low error and be applicable to that outer channel is a kind of device of offsetting based on the repeater echo of additional signal of multipath channel.

Another object of the present invention provide a kind ofly estimate that echo channel impulse response relative error is less, the data length during computing is little, complexity is low, real-time good, hardware is realized simply the repeater echo counteracting method based on additional signal.

In order to solve the problems of the technologies described above, a kind of technical scheme that the present invention adopted is:

A kind of device of offsetting based on the repeater echo of additional signal; Said device includes receiver module, additional signal module and echo channel parameter matrix estimation module; The output of said receiver module is connected with Digital Down Converter Module, signal subtraction module, signal plus module, Digital Up Convert module, power amplifier module and transmitter module in turn; The output of said additional signal module connects the input of signal plus module and the input of echo channel parameter matrix estimation module respectively; The output of said Digital Down Converter Module also is connected to the input of echo channel parameter matrix estimation module; The output of said signal plus module also is connected to the input of echo channel parameter matrix estimation module respectively, and the output of said echo channel parameter matrix estimation module is connected to the input of signal subtraction module.

Further, said echo channel parameter matrix estimation module includes the first cross-correlation submodule, the second cross-correlation submodule, deconvolution submodule, correcting process submodule and estimates the echo channel submodule; The output of the said first cross-correlation submodule and the second cross-correlation submodule all is connected to the input of deconvolution submodule, and the deconvolution submodule connects the correcting process submodule successively, estimates the echo channel submodule; The output of the output of said Digital Down Converter Module and additional signal module is connected to the input of the first cross-correlation submodule; The output of the output of said signal plus module and additional signal module is connected to the input of the second cross-correlation submodule, and the output of said estimation echo channel submodule is connected to the input of signal subtraction module.

Further, the additional signal that said additional signal module produces is stored in the additional signal module, and said additional signal is approximately 0 with the useful base station signal cross correlation that receiver module after Digital Down Convert receives.

The another kind of technical scheme that the present invention adopted is:

A kind of method of offsetting based on the repeater echo of additional signal said method comprising the steps of:

A, repeater initialization;

B, generation additional signal;

After the signal plus that C, additional signal and the repeater behind Echo Cancellation receive, handle through Digital Up Convert and power amplification successively, be input to the output of transmitter module radio frequency.

Further, said step B comprises following substep:

B1, wait for Δ τ second, open the enable switch SHIFT of add-on module;

B2, open opening entry additional signal z (n) constantly, be stored among the register REG0 from the enable switch SHIFT of add-on module;

B3, when the data number of storing among the REG0 reaches N, close enable switch SHIFT, wherein N is the sampling number of additional signal.

Further, the Echo Cancellation process among the said step C comprises following substep:

C1, additional signal z (n) adopt the data block processing mode based on the discrete digital signal with the signal y (n) that the repeater receives, and calculate the cross-correlation function R of these two signals _Zy(m), be stored among the register REG1;

C2, additional signal z (n) adopt the data block processing mode based on the discrete digital signal with the signal x (n) of repeater emission, calculate the cross-correlation function R of these two signals _Zx(m), be stored among the register REG2;

C3, the output signal of above two the cross-correlation submodules input signal

as the deconvolution submodule is stored among the register REG3;

C4, correction operations;

C5, read the repeater echo channel parameter matrix that the value

of storing among the register REG3 is estimated for this method;

C6, the estimating received signal that calculates according to echo channel parameter matrix

, the signal y (n) that estimating received signal and actual repeater are received subtract each other does the Echo Cancellation operation.

Further, the frequency of said additional signal is the frequency that is in useful base station signal frequency spectrum hole, repeater.

Further, the power ratio repeater of said additional signal receives more than the little 20dB of power of useful base station signal.

Further, the sequence length of handling in the said cross-correlation submodule is got L=22.

The invention has the beneficial effects as follows: the device that the present invention is based on the repeater echo counteracting of additional signal is that the frequency spectrum hole less single frequency sinusoidal signal of place's interpolation amplitude that is utilized in the base station useful signal is assisted the completion channel estimating, adds signal and can not cause signal to disturb the cellphone subscriber of overlay area, repeater.

Another one beneficial effect of the present invention is: the repeater echo counteracting method that the present invention is based on additional signal is under the frequency selective fading channels model of COST 207 standards, and the relative error of main footpath attenuation coefficient is 1.7417 * 10 ^-5The estimation echo can be followed the tracks of actual ghosts preferably; Thereby reach the purpose that effective elimination echo disturbs; And estimate that echo channel impulse response relative error is less, the data length during computing is little, complexity is low, real-time is good, hardware is realized simply, offsets the back signal and does not have the process of convergence gradually.

Description of drawings

Fig. 1 is based on the Echo Cancellation know-why block diagram of sef-adapting filter principle;

Fig. 2 is based on the theory diagram of the device and method that the repeater echo of additional signal offsets;

Fig. 3 is based on the structured flowchart of the device that the repeater echo of additional signal offsets.

Fig. 4 is based on the flow chart of steps of repeater echo counteracting method one embodiment of additional signal;

Fig. 5 is based on the flow chart of steps of another embodiment of repeater echo counteracting method of additional signal.

Embodiment

Be described further below in conjunction with the accompanying drawing specific embodiments of the invention:

As shown in Figure 3; A kind of device of offsetting based on the repeater echo of additional signal; This device includes receiver module, additional signal module and echo channel parameter matrix estimation module; The output of said receiver module is connected with Digital Down Converter Module, signal subtraction module, signal plus module, Digital Up Convert module, power amplifier module and transmitter module in turn; The output of said additional signal module connects the input of signal plus module and two inputs of echo channel parameter matrix estimation module respectively; The output of said Digital Down Converter Module also is connected to the input of echo channel parameter matrix estimation module; The output of said signal plus module also is connected to two inputs of echo channel parameter matrix estimation module respectively, and the output of said echo channel parameter matrix estimation module is connected to the input of signal subtraction module.

Further as preferred embodiment, said echo channel parameter matrix estimation module includes the first cross-correlation submodule, the second cross-correlation submodule, deconvolution submodule, correcting process submodule and estimates the echo channel submodule; The output of the said first cross-correlation submodule and the second cross-correlation submodule all is connected to the input of deconvolution submodule, and the deconvolution submodule connects the correcting process submodule successively, estimates the echo channel submodule; The output of the output of said Digital Down Converter Module and additional signal module is connected to the input of the first cross-correlation submodule; The output of the output of said signal plus module and additional signal module is connected to the input of the second cross-correlation submodule, and the output of said estimation echo channel submodule is connected to the input of signal subtraction module.

Further as preferred embodiment, the additional signal that said additional signal module produces is stored in the additional signal module, and said additional signal is approximately 0 with the useful base station signal cross correlation that receiver module after Digital Down Convert receives.

A kind of method of offsetting based on the repeater echo of additional signal as shown in Figure 4, that a specific embodiment provides, this method may further comprise the steps:

A, repeater initialization;

B, generation additional signal;

After the signal plus that C, additional signal and the repeater behind Echo Cancellation receive, handle through Digital Up Convert and power amplification successively, be input to the output of transmitter module radio frequency.

A kind of method of offsetting based on the repeater echo of additional signal as shown in Figure 5, that another specific embodiment provides, this method may further comprise the steps:

A, repeater initialization;

B1, wait for Δ τ second, open the enable switch SHIFT of add-on module, if can switch open be t constantly ₀, wherein Δ τ is that receiver module receives signal from the repeater, and exports the time delay of process through Digital Down Converter Module;

B2, from t ₀Opening entry additional signal z (n) is stored among the register REG0 constantly;

B3, when the data number of storing among the REG0 reaches N, close enable switch SHIFT, wherein N is the sampling number of additional signal;

C1, add-on module additional signal z (n) that produces and the signal y (n) that the repeater receiver module receives all are input to the cross-correlation submodule; Employing is based on the data block processing mode of discrete digital signal; The data block length that will carry out the echo channel estimation is designated as N, calculates the cross-correlation function R of these two signals _Zy(m), wherein m ∈ [(N-1), (N-1)] is stored among the register REG1;

C2, the radiofrequency signal x (n) that the additional signal z (n) and the repeater transmitter module of add-on module generation are launched all are input to the cross-correlation submodule, and the data block length of z (n) and x (n) is designated as N, calculates the cross-correlation function R of these two signals _Zx(m), wherein m ∈ [(N-1), (N-1)] is stored among the register REG2;

C3, with the output of above two cross-correlation submodules input signal as the deconvolution submodule; Deconvolution submodule output

is for estimating the parameter matrix of echo channel; Be stored among the register REG3, the maximum of getting REG3 is MAX1;

C4, correction operations:

If

REG3 will register the corresponding

value is set to 0;

If

is retained in the corresponding register REG3

value;

C5, read the repeater echo channel parameter matrix that the value

of storing among the register REG3 is estimated for this method.

C6, the estimating received signal that calculates according to echo channel parameter matrix

, the signal y (n) that estimating received signal and actual repeater are received subtract each other does the Echo Cancellation operation;

After C7, the signal plus, get into the Digital Up Convert module,, be input to transmitter module through power amplifier module with the additional signal of add-on module generation and the repeater receiver module reception behind Echo Cancellation.

Further as preferred embodiment, the repeater echo bucking-out system specifically is provided with as follows:

S1, said additional signal module position are arranged on before the repeater Digital Up Convert module position;

S2, said additional signal frequency should be and be in the frequency that the repeater receives useful base station signal frequency spectrum hole;

S3, said additional signal power should receive more than the little 20dB of power of useful base station signal than the repeater;

S4, said additional signal launch time should be in the repeater initialization finish and when in running order;

S5, said additional signal sample frequency should be consistent with the sampling rate in the digital signal processing of repeater;

List entries length in S6, the said cross-correlation submodule should be relevant with the actual ghosts channel of repeater true environment of living in, for estimating the echo channel parameter matrix in real time, gets L=22.

The present invention proposes a kind of small-signal that in forward signal, adds, the algorithm that utilizes this signal that echo channel is estimated, thus realize the Echo Cancellation of repeater.This algorithm can be realized the real-time estimation to echo channel, owing to the data block length that carries out channel estimating is less, even under the fast-changing in time situation of echo channel characteristic, still have stronger follow-up control.

With reference to Fig. 2, the present invention estimates the actual ghosts channel parameter matrix of repeater environment of living in, realizes the system principle diagram of Echo Cancellation.Omitted the processing procedure of radiofrequency signal to baseband signal among the figure, the signal flow of down link is to relation when only having illustrated that the repeater works in base band.

The donor signal that s (n) receives for the repeater donor antenna; Z (n) is an additional signal; X (n) is the forward signal at retransmitting antenna place, repeater; X' (n) is the echo-signal that the repeater forward signal produces through the actual ghosts channel, and y (n) is the signal that donor antenna receives, and is made up of s (n) and x ＇ (n) two parts.The effect of echo channel estimation module is to be calculated the model parameter of echo channel with z (n), and given the estimation echo channel by x (n), y (n).X (n) is input to and estimates that echo channel obtains estimating that the difference signal after echo

subtracts each other y (n) and

is designated as e (n); If estimate that echo channel is of equal value with actual echo channel; Then

equates with x' (n); E (n) is exactly pure donor signal s (n), thereby has realized the echo elimination.

It is pointed out that to have comprised additional signal z (n) in the forward signal, so must guarantee that this signal does not influence the normal reception of donor signal.In this article, z (n) is a single frequency sinusoidal signal, because donor signal is the known mobile communication signal of spectrum allocation may rule, therefore, an edge that only needs z (n) to be loaded into the donor signal frequency band get final product, and the energy of controlling z (n) is less than e (n) more than the 20dB.For more general situation, cognitive radio technology capable of using is found out the frequency spectrum hole near donor signal, and then realizes the loading of additional signal.

When can being modeled as, echo channel becomes multidiameter fading channel.But in a fully short time period, the time variation of echo channel can be ignored.In the less signal processing of this data length, echo channel can be modeled as the FIR filter of tapped delay line form.The amplitude fading coefficient of each tap line of filter is arranged the parameter matrix that just can obtain the actual ghosts channel according to the order of sequence:

H=[h(1),h(2),…,h(n),…,h(M)] （3.1）

Wherein, M is the number of element in the actual ghosts channel parameter matrix, i.e. the exponent number of FIR filter.The concrete value of M is confirmed by the maximum delay amount and the sample frequency of echo.To the estimation of actual ghosts channel, by x (n), y (n) and z (n) H is estimated exactly.

Algorithm Analysis: this paper algorithm use is based on the data block processing mode of discrete digital signal, and the data block length that will carry out the echo channel estimation is designated as N, and then additional signal z (n) and repeater receive the cross-correlation function R of signal y (n) _Zy(m) be:

$R_{\mathrm{zy}}\left(m\right)=E\left[z\left(n\right)y(n+m)\right]$

$=E\left\{z\left(n\right)\right[s(n+m)+h\left(n\right)\⊗x(n+m)\left]\right\}$

$=E\left\{z\left(n\right)\right[s(n+m)+\underset{k=-\∞}{\overset{+\∞}{\mathrm{\Σ}}}h\left(k\right)x(n+m-k)\left]\right\}$

$=R_{\mathrm{zs}}\left(m\right)+E\left\{z\left(n\right)\right[\underset{k=-\∞}{\overset{+\∞}{\mathrm{\Σ}}}h\left(k\right)x(n+m-k)\left]\right\}---\left(3.2\right)$

$=R_{\mathrm{zs}}\left(m\right)+\underset{k=-\∞}{\overset{+\∞}{\mathrm{\Σ}}}h\left(k\right)E\left[z\left(n\right)x(n+m-k)\right]$

$=R_{\mathrm{zs}}\left(m\right)+\underset{k=-\∞}{\overset{+\∞}{\mathrm{\Σ}}}h\left(k\right)R_{\mathrm{zx}}(m-k)$

$=R_{\mathrm{zs}}\left(m\right)+h\left(m\right)\⊗R_{\mathrm{zx}}\left(m\right)$

Wherein,

The expression linear convolution; R _Zs(m) be cross-correlation function between additional signal z (n) and the donor signal s (n); R _Zx(m) be cross-correlation function between additional signal z (n) and the forward signal x (n); H (m) is an element among the actual ghosts channel parameter matrix H;

m∈[-(N-1)，(N-1)]。

If R _Zs(m) satisfy (3.3) formula:

R _zs(m)≈0 (3.3)

Be that cross correlation between additional signal z (n) and the donor signal s (n) is less, R _Zs(m) be approximately 0.Then (3.2) but the formula abbreviation be:

$R_{\mathrm{zy}}\left(m\right)=h\left(m\right)\⊗R_{\mathrm{zx}}\left(m\right)---\left(3.4\right)$

Can know that by following formula each element value of actual ghosts channel parameter matrix H can be by R _Zy(m) deconvolution R _Zx(m) obtain.

Order

n=m+N

And substitution (3.4) formula, can get:

$R_{\mathrm{zy}}(n-N)=h(n-N)\⊗R_{\mathrm{zx}}(n-N)$ （3.5）

If R _Zx(-N+1) ≠ 0, (3.5) formula can be written as time domain iterative solution convolution form:

$\hat{h}\left(n\right)\≈\left\{\begin{array}{cc}{R}_{\mathrm{zy}}(-N+1)/R_{\mathrm{zx}}(-N+1)& n=1\\ [R_{\mathrm{zy}}(n-N)-\underset{k=-N+1}{\overset{n-N-1}{\mathrm{\Σ}}}h(n-N-k)R_{\mathrm{zx}}(k+1)]/R_{\mathrm{zx}}(-N+1)& 2\≤n\≤2N-1\end{array}\right.$

（3.6）

Order $\hat{H}=[\hat{h}\left(1\right),\hat{h}\left(2\right),...,\hat{h}\left(n\right),...,\hat{h}(2N-1)],$ For estimating the echo channel parameter matrix.

Angle analysis from mathematics; Comprehensively (3.1) formula and (3.4) Shi Kede are as long as carry out the integer value that the data block length of channel estimating is got

.But angle analysis from physical significance; The number M of element in the actual ghosts channel parameter matrix; Show that any echo effect of current time can have influence on a follow-up M sampled point, in other words before constantly the echo effect of M sampled point can have influence on current time certain a bit.Therefore, the data block length N that carries out channel estimating should get the integer value more than or equal to M.

In the echo channel estimation procedure; Because the number M of element is a unknown quantity in the actual ghosts channel parameter matrix; For guaranteeing that

that estimate has certain remaining simultaneously from the consideration of estimated accuracy, should suitably strengthen the value of N.

can appear like this and with H in the inconsistent problem of element number, need carry out correcting process this moment to

.(3.6) formula of analysis can be known R _Zx(n-N) item fully little in can cause current solution

Increase, iterative process can be aggravated the trend that follow-up element progressively increases, and finally exists In ghost peak will appear, easily it is judged to main footpath echo, have a strong impact on the performance of algorithm.Therefore, according to R _Zx(n-N) mean value of initial several elements is provided with appropriate thresholds in, with R _Zx(n-N) be designated as i less than the position that equals threshold value in, then the scope of (3.6) formula iterative can be modified to 2≤n≤i-1.

Performance when selecting for use the relative error δ that leads footpath echo amplitude attenuation coefficient that this paper algorithm is used for Echo Cancellation is assessed; The size of δ can reflect the quality of this paper algorithm estimation echo channel overall performance; Relative error is more little; Explain and estimate that the echo channel impulse response approaches actual echo channel impulse response more, the echo that estimates approaches actual ghosts more, and the effect of Echo Cancellation is just good more; Otherwise then the effect of Echo Cancellation is poor more.

More than be that preferable enforcement of the present invention is specified; But the invention is not limited to said embodiment; Those of ordinary skill in the art can also make all equivalent variations or replacement under the prerequisite of spirit of the present invention, distortion that these are equal to or replacement all are included in the application's claim institute restricted portion.

Claims (9)

1. device of offsetting based on the repeater echo of additional signal; It is characterized in that: include receiver module, additional signal module and echo channel parameter matrix estimation module; The output of said receiver module is connected with Digital Down Converter Module, signal subtraction module, signal plus module, Digital Up Convert module, power amplifier module and transmitter module in turn; The output of said additional signal module connects the input of signal plus module and the input of echo channel parameter matrix estimation module respectively; The output of said Digital Down Converter Module also is connected to the input of echo channel parameter matrix estimation module; The output of said signal plus module also is connected to the input of echo channel parameter matrix estimation module respectively, and the output of said echo channel parameter matrix estimation module is connected to the input of signal subtraction module.

2. device of offsetting based on the repeater echo of additional signal according to claim 1 is characterized in that: said echo channel parameter matrix estimation module includes the first cross-correlation submodule, the second cross-correlation submodule, deconvolution submodule, correcting process submodule and estimates the echo channel submodule; The output of the said first cross-correlation submodule and the second cross-correlation submodule all is connected to the input of deconvolution submodule, and the output of deconvolution submodule is connected through the correcting process submodule and then with the input of estimating the echo channel submodule; The output of the output of said Digital Down Converter Module and additional signal module all is connected to the input of the first cross-correlation submodule; The output of the output of said signal plus module and additional signal module all is connected to the input of the second cross-correlation submodule, and the output of said estimation echo channel submodule is connected to the input of signal subtraction module.

3. device of offsetting according to claim 1 and 2 based on the repeater echo of additional signal; It is characterized in that: the additional signal that said additional signal module produces is stored in the additional signal module, and said additional signal is approximately 0 with the useful base station signal cross correlation that receiver module after Digital Down Convert receives.

4. repeater echo counteracting method based on additional signal is characterized in that: said method comprising the steps of:

A, repeater initialization;

B, generation additional signal;

After the signal plus that C, additional signal and the repeater behind Echo Cancellation receive, handle through Digital Up Convert and power amplification successively, be input to the output of transmitter module radio frequency.

5. according to the repeater echo counteracting method based on additional signal described in the claim 4, it is characterized in that: said step B comprises following substep:

B1, wait

second, open the enable switch SHIFT of add-on module;

B2, open opening entry additional signal

constantly, be stored among the register REG0 from the enable switch SHIFT of add-on module;

B3, when the data number of storing among the REG0 reaches ; Close enable switch SHIFT, wherein

is the sampling number of additional signal.

6. according to the repeater echo counteracting method based on additional signal described in the claim 4, it is characterized in that: the Echo Cancellation process among the said step C comprises following substep:

C1, additional signal

adopt the data block processing mode based on the discrete digital signal with the signal

that the repeater receives; Calculate the cross-correlation function

of these two signals, be stored among the register REG1;

C2, additional signal

adopt the data block processing mode based on the discrete digital signal with the signal of repeater emission; Calculate the cross-correlation function

of these two signals, be stored among the register REG2;

C3, with the output signal of above-mentioned two cross-correlation submodules input signal

as the deconvolution submodule, be stored among the register REG3;

C4, correction operations;

C5, read the value

of storing among the register REG3,

be the repeater echo channel parameter matrix that this method is estimated;

C6, the estimating received signal that calculates according to echo channel parameter matrix

, the signal that estimating received signal and actual repeater are received subtracts each other does the Echo Cancellation operation.

7. according to claim 4, the repeater echo counteracting method based on additional signal described in 5 or 6, it is characterized in that: the frequency of said additional signal is the frequency that is in useful base station signal frequency spectrum hole, repeater.

8. according to claim 4, the repeater echo counteracting method based on additional signal described in 5 or 6, it is characterized in that: the power ratio repeater of said additional signal receives more than the little 20dB of power of useful base station signal.

9. according to claim 4, the repeater echo counteracting method based on additional signal described in 5 or 6, it is characterized in that: the sequence length of handling in the said cross-correlation submodule is got L=22.

Images