CN101651463A - Method and device for suppressing narrowband interference of baseband signals - Google Patents

Abstract

The invention discloses a method and a device for suppressing narrowband interference of baseband signals. The method comprises the following steps: acquiring the baseband signals of received signalsafter passing through a pulse shaping filter; carrying out fast Fourier transform for the baseband signals to acquire frequency domain signals of the received signals; filtering frequency point signals in a pass band, a transition band and a stop band of the pulse shaping filter in the frequency domain signals according to the frequency response chrematistics of the pulse shaping filter respectively; and carrying out inverse fast Fourier transform for the filtered frequency domain signals to acquire the baseband signals of the received signals. Compared with the narrowband interference suppression algorithm which adopts an identical threshold and an identical processing method in the prior art, the method and the device after implementation can improve the narrowband interference suppression capacity of a communication system.

Description

A kind of inhibition method and device of baseband signal narrow band interference

Technical field

The present invention relates to Communication Jamming inhibition technology, particularly a kind of inhibition method and device of baseband signal narrow band interference.

Background technology

DSSS (Direct Sequence Spread Spectrum, direct sequence spread spectrum) system is one of spread spectrum principal mode in actual applications.Strong anti-interference performance not only, communication security is good, and Project Realization is simple relatively, therefore is widely used in military field, satellite communication and digital mobile communication system etc.Along with the electronic technology develop rapidly, frequency spectrum resource is deficient day by day, and aerial electromagnetic environment also constantly worsens, and the interference free performance of DSSS system is had higher requirement.Especially in following military struggle field, the strong narrow band interference of enemy's malice tends to the jamming margin of the system that breaks through, and causes systematic function decline even malfunctioning.Therefore be necessary before the signal despreading, to adopt the corresponding signal process technology, suppress to disturb, improve systematic function.

In recent years, very active always around the research of spread spectrum communication interference mitigation technology, number of research projects is paid close attention to effectively exploitation, utilization and the development of Suppression of narrow band interference technology in the spread spectrum system always.The implementation method of interference mitigation technology is a lot, specifically comprises time-domain adaptive filtering interference mitigation technology and transform domain interference mitigation technology.Wherein time-domain adaptive filtering comprise prediction estimation filter and decision feedback filter device, all be to utilize the inhibition that realizes a little less than the correlation of the strong and spread-spectrum signal of the correlation of narrow band interference narrow band interference.For adaptive-filtering.The Nonlinear Processing technology is more effective than linear technique.Nonlinear function is introduced into filter and constitutes the nonlinear filtering system, and evolution algorithm and neural network algorithm also are introduced into the stability that is used to improve the nonlinear filter system.The adaptive-filtering of time domain is handled has Suppression of narrow band interference ability completely, but convergence rate is unhappy, relatively is suitable for handling the narrow band interference that becomes slowly.The transform domain interference mitigation technology is used to offset single-frequency, multifrequency and narrow band interference: can be divided into DFT (Discrete Fourier Transform, discrete Fourier transform (DFT)), DCT (Discrete Cosine Transform, discrete cosine transform), ST (SubBand Transform, sub-band transforms), WPT (wavelet packet transform, wavelet package transforms) etc.Along with FFT (Fast Fourier Transform, fast fourier transform) appearance of algorithm and developing rapidly of large-scale circuit, make many conversion be able to real-time implementation, so the transform domain treatment technology become the research focus that disturbs the inhibition field.

In most spread spectrum communication systems, have only the strong especially narrow band interference of minority to have a strong impact on systematic function.And in spread spectrum communication, the ratio of the strong shared whole broadband of narrow band interference frequency range is very low.If with the target signal filter of these frequency ranges, then strong narrow band interference will obtain good restraining, and the spread-spectrum signal power loss is very little.Transform domain Suppression of narrow band interference filter just is based on spread-spectrum signal and this characteristics design of narrow band interference on frequency domain.

Fig. 1 is a transform domain Suppression of narrow band interference filter basic structure schematic diagram, and as shown in Figure 1, received signal x (k) transforms to frequency domain through FFT.Each frequency and interference suppression filter corresponding points multiply each other, and are multiplied by frequency domain filter coefficient { W respectively _i, disturb inhibition through the output of IFFT (Inverse Fast Fourier Transform, invert fast fourier transformation) back, thereby realize the inhibition of narrow band interference.

In order to suppress narrow band interference to greatest extent, make the performance loss minimum of communication system simultaneously, Filter Design is very crucial.In common algorithm, be mostly a frequency-region signal and a thresholding are compared, be lower than the reservation of thresholding, surpass the Filtering Processing of carrying out of thresholding.Generally speaking, whole frequency signals of received signal have been considered in the selection of thresholding, and adopt same thresholding to carry out filtering for all frequency signals, just the processing method of making no exception of all frequency signals to received signal.

The deficiencies in the prior art are: when the processing method of making no exception by prior art all frequency signals to received signal, promptly adopt same thresholding to come the method for filtering narrow band interference can not make the Suppression of narrow band interference ability of system reach best.

Summary of the invention

The technical problem that the present invention solves has been to provide a kind of inhibition method and device of baseband signal narrow band interference, in order to improve the inhibition ability to the baseband signal narrow band interference.

The present invention provides a kind of inhibition method of baseband signal narrow band interference in an embodiment, comprises the steps:

Obtain the baseband signal of received signal after passing through the pulse-shaping filter;

Baseband signal is obtained the frequency-region signal of received signal after the FFT conversion;

According to the pulse-shaping filter response frequency signal in the pulse-shaping filter passband in the described frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band are carried out filtering respectively;

Filtered frequency-region signal is obtained the baseband signal of received signal after the IFFT conversion.

Preferably, determine frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband in the frequency-region signal, be specially:

Determine the impulse Response Function of pulse-shaping filter according to the sampling period of received signal;

Determine the transfer function of the impulse Response Function of pulse-shaping filter;

The Frequency Response of determining according to described transfer function determines that the frequency-region signal of received signal is frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband.

Preferably, described pulse-shaping filter is a root raised cosine filter;

Frequency signal in the pulse-shaping filter passband in described definite frequency-region signal, the frequency signal in the transition band and the frequency signal in the stopband are specially:

Satisfy $0\≤\left|f\right|\≤\frac{1-\mathrm{\α}}{{2T}_s}$ The frequency signal be frequency signal in the passband;

Satisfy $\frac{1-\mathrm{\α}}{{2T}_s}\≤\left|f\right|\≤\frac{1+\mathrm{\α}}{{2T}_s}$ The frequency signal be frequency signal in the transition band;

Satisfy $\frac{1+\mathrm{\&alpha;}}{{2T}_s}<\left|f\right|\&le;B$ The frequency signal be frequency signal in the stopband;

Wherein: f is a frequency, and α is a rolloff-factor, T _sBe the sampling period of received signal, B is the bandwidth of received signal.

Preferably, described frequency signal in the passband is carried out filtering, is specially:

The setting filter threshold is: Th _p=μ * M _Av, wherein:

M _AvBe the amplitude equalizing value of all the frequency signals in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _Av

The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time.

Amplitude is surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

Preferably, described frequency signal in the transition band is carried out filtering, is specially:

The setting thresholding is: Th _p=μ * M _Av, or, setting thresholding TH according to the attenuation characteristic segmentation that receives formed filter _t=β * TH _p, wherein:

M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter;

The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time; TH _pBe the filter threshold in the passband, β is the decay factor of determining according to the ratio of the frequency domain amplitude in the passband of the frequency domain amplitude of the reception formed filter of the frequency signal correspondence of carrying out filtering and reception formed filter;

The amplitude that amplitude is surpassed the frequency signal of thresholding is changed to 0, or is changed to predefined amplitude; The reservation amplitude is lower than the amplitude of the frequency signal of thresholding.

Preferably, described frequency signal in the stopband is carried out filtering.Be specially:

The amplitude of the frequency signal in the stopband is changed to 0, perhaps is changed to value near 0.

The present invention also provides a kind of restraining device of baseband signal narrow band interference in an embodiment, comprising:

Acquisition module is used to obtain the baseband signal of received signal after passing through the pulse-shaping filter;

Conversion module is used for baseband signal is obtained the frequency-region signal of received signal after the FFT conversion;

Filtration module is used for according to the pulse-shaping filter response frequency signal in the pulse-shaping filter passband of frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band being carried out filtering respectively;

Inverse transform module is used for filtered frequency-region signal is obtained the baseband signal of received signal after the IFFT conversion.

Preferably, described filtration module is further used for determining according to the sampling period of received signal the impulse Response Function of pulse-shaping filter; Determine the transfer function of pulse-shaping filter impulse Response Function; Determine that according to the Frequency Response of determining in the described transfer function frequency-region signal of received signal is frequency signal, frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband.

Preferably, described pulse-shaping filter is a root raised cosine filter;

Described filtration module be further used for

Satisfy $0\&le;\left|f\right|\&le;\frac{1-\mathrm{\&alpha;}}{{2T}_s}$ The frequency signal be defined as frequency signal in the passband;

Satisfy $\frac{1-\mathrm{\&alpha;}}{{2T}_s}\&le;\left|f\right|\&le;\frac{1+\mathrm{\&alpha;}}{{2T}_s}$ The frequency signal be defined as frequency signal in the transition band;

Satisfy $\frac{1+\mathrm{\&alpha;}}{{2T}_s}<\left|f\right|\&le;B$ The frequency signal be defined as frequency signal in the stopband;

Wherein: f is a frequency, and α is a rolloff-factor, T _sBe the sampling period of received signal, B is the bandwidth of received signal.

Preferably, described filtration module carries out filtering after being further used for setting thresholding in passband, sets described thresholding:

Th _p=μ * M _Av, wherein:

M _AvBe the amplitude equalizing value of all the frequency signals in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _Av

The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time;

After setting described thresholding, amplitude is surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

Preferably, described filtration module carries out filtering after being further used for setting thresholding in transition band, sets thresholding and is:

Th _p=μ * M _Av, or, setting thresholding TH according to the attenuation characteristic segmentation that receives formed filter _t=β * TH _p, wherein:

M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter;

The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time;

TH _pBe the filter threshold in the passband, β is the decay factor of determining according to the ratio of the frequency domain amplitude in the passband of the frequency domain amplitude of the reception formed filter of the frequency signal correspondence of carrying out filtering and reception formed filter;

After setting described thresholding, the amplitude that amplitude is surpassed the frequency signal of thresholding is changed to 0, or is changed to predefined amplitude; The reservation amplitude is lower than the amplitude of the frequency signal of thresholding.

Preferably, described filtration module is further used for the amplitude of the frequency signal in the stopband is changed to 0, perhaps is changed to the value near 0.

Embodiment of the invention beneficial effect is as follows:

Taken into full account the spectral characteristic of signal in the invention process by the received pulse formed filter, promptly, during the frequency-region signal that after the FFT conversion, obtains in baseband signal, according to the pulse-shaping filter response frequency-region signal of received signal is divided into frequency signal in the pulse-shaping filter passband, frequency signal in the transition band and the frequency signal in the stopband, and adopt different thresholdings to suppress narrow band interference with different treating methods to the frequency range of signal, that is the frequency signal in the paired pulses formed filter passband,, frequency signal in the transition band and the frequency signal in the stopband are set thresholding respectively and are carried out filtering; Compare with the Suppression of narrow band interference algorithm of same thresholding of available technology adopting and same treating method, can improve the Suppression of narrow band interference ability of communication system after the invention process.

Description of drawings

Fig. 1 is the filter of transform domain Suppression of narrow band interference described in a prior art basic structure schematic diagram;

Fig. 2 is the inhibition method implementing procedure schematic diagram of baseband signal narrow band interference described in the embodiment of the invention;

Fig. 3 is that input described in the embodiment of the invention is implemented schematic diagram;

Fig. 4 is the restraining device structural representation of baseband signal narrow band interference described in the embodiment of the invention.

Embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described.

Because mobile telecommunication channel is typical bandwidth efficient channel, in order to suppress intersymbol interference, mobile communication system has all adopted the pulse-shaping filter in the sending and receiving end.Received signal by the pulse-shaping filter that receives after, the frequency signal of received signal just can be divided into frequency signal in the pulse-shaping filter passband, frequency signal in the transition band and the frequency signal in the stopband according to the pulse-shaping filter response.And the intensity that is in the frequency signal in the different sections has very big difference, based on this, has proposed to be applicable to the Suppression of narrow band interference scheme of base band in the invention process.In solution, it is contemplated that: according to the characteristics of received pulse formed filter, the spectrum region of received signal is divided into passband, transition band and stopband, and to the different thresholdings and different treating methods of the employing of the frequency signal in these 3 different frequency bands, thereby overcome the deficiency that only exists single thresholding to carry out filtering in the prior art, make that the effect that suppresses narrow band interference is better.

Fig. 2 is the inhibition method implementing procedure schematic diagram of baseband signal narrow band interference, as shown in the figure, can comprise the steps: when interference is suppressed

Step 201, obtain received signal by the baseband signal behind the pulse-shaping filter;

Step 202, baseband signal obtained the frequency-region signal of received signal after the FFT conversion;

Step 203, the frequency signal in the pulse-shaping filter passband in the frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band are carried out filtering respectively according to the pulse-shaping filter response;

Step 204, filtered frequency-region signal obtained the baseband signal of received signal after the IFFT conversion.

Concrete enforcement to each step describes below.

If the signal s (t) of DSSS system has sneaked into additive white Gaussian noise and narrow band interference in the Channel Transmission process, then received signal x (t) can be expressed as:

$x\left(t\right)=s\left(t\right)+\underset{l=1}{\overset{q}{\mathrm{\&Sigma;}}}{i}_l\left(t\right)+n\left(t\right)---\left(1\right)$

Wherein, i _l(t) be narrow band interference, uncorrelated each other between each narrow band interference; N (t) is a white Gaussian noise, and is all uncorrelated with signal and narrow band interference.

Then x (t) is sampled, during signal sampling, with variable be worth continuous analog signal all and successively be converted on discrete signal discrete on the variable and value also discrete digital signal (quantification), the discrete form of acquisition received signal is:

$x\left(m\right)=s\left(m\right)+\underset{l=1}{\overset{q}{\mathrm{\&Sigma;}}}{i}_l\left(m\right)+n\left(m\right)---\left(2\right)$

Jamproof purpose just is as far as possible to disturbing i _l(m) suppress, so that correct recovering information sequence s (m).

Fig. 3 implements schematic diagram for input, as shown in the figure, in the signal detection process of the DSSS mobile communication system that has added base band Suppression of narrow band interference device, suppress to handle through carrying out the base band arrowband behind the pulse-shaping filter more earlier, after received signal was by the pulse-shaping filter that receives, the frequency signal of received signal just can be divided into frequency signal in the pulse-shaping filter passband, frequency signal in the transition band and the frequency signal in the stopband according to the pulse-shaping filter response.

In the enforcement, at first in step 201, obtain the baseband signal of received signal after passing through the pulse-shaping filter; In step 202, baseband signal is obtained the frequency-region signal of received signal then after the FFT conversion, after obtaining frequency-region signal, just can execution in step 203, below step 202,203 concrete enforcement are described.

Pulse-shaping filter in the mobile communication system generally adopts root raised cosine filter, and the example that is embodied as with root raised cosine filter describes below.Adopting root raised cosine filter among the embodiment mainly is that what to consider that the standard of existing 3G all adopts is root raised cosine filter, therefore be that example describes with the root raised cosine filter, but those skilled in the art easily know, in the pulse-shaping filter, except root raised cosine filter, can be used for implementing so long as can suppress the pulse-shaping filter of intersymbol interference.

For root raised cosine filter, its impulse response RC ₀(t) be:

${\mathrm{RC}}_0\left(t\right)\frac{2\mathrm{\&alpha;}}{\mathrm{\&pi;}\sqrt{T_s}}\frac{\frac{\sin \left((1-\mathrm{\&alpha;})\mathrm{\&pi;}\frac{t}{T_s}\right)}{4\mathrm{\&alpha;}\frac{t}{T_s}}+\cos \left((1+\mathrm{\&alpha;})\mathrm{\&pi;}\frac{t}{T_s}\right)}{(1-{\left(4\mathrm{\&alpha;}\frac{t}{T_s}\right)}^2)}---\left(3\right)$

Wherein, rolloff-factor α=0.22, T _sBe the sampling period of received signal.

If $Z\left(f\right)=\begin{array}{c}\left\{\begin{array}{cc}{T}_s& 0\&le;\left|f\right|\&le;\frac{1-\mathrm{\&alpha;}}{{2T}_s}\\ \frac{T_s}{2}\{1+\cos [\frac{\mathrm{\&pi;}{T}_s}{\mathrm{\&alpha;}}\left(\right|f|-\frac{1-\mathrm{\&alpha;}}{{2T}_s})\left]\right\}& \frac{1-\mathrm{\&alpha;}}{{2T}_s}\&le;\left|f\right|\&le;\frac{1+\mathrm{\&alpha;}}{{2T}_s}\\ 0& \left|f\right|>\frac{1+\mathrm{\&alpha;}}{{2T}_s}\end{array}---\left(4\right)\right.\end{array}$

In the following formula, being that the Z transfer function of time frequency signal t is expressed, is variable with frequency f in the Z transfer function.So, the transfer function RC of root raised cosine filter ₀(f) be:

RC ₀(f)＝|Z(f) ^1/2| (5)

Root raised cosine filter is the filter that satisfies the Nquist criterion, and it can overcome intersymbol interference fully, but because impulse response RC ₀(t) be non-causal,, exist like this so it must brachymemma $\left|f\right|>\frac{1+\mathrm{\&alpha;}}{{2T}_s}$ Those frequency spectrum points just no longer be zero.

The bandwidth of supposing received signal is that B is (common $B>\frac{1+\mathrm{\&alpha;}}{{2T}_s}$ ), according to the transfer function RC of root raised cosine filter ₀(f) characteristics can be the frequency signal distinguishing of received signal following 3 sections:

1), satisfies $0\&le;\left|f\right|\&le;\frac{1-\mathrm{\&alpha;}}{{2T}_s}$ Those frequency signals be made as passband B _pInterior point;

2), satisfy $\frac{1-\mathrm{\&alpha;}}{{2T}_s}\&le;\left|f\right|\&le;\frac{1+\mathrm{\&alpha;}}{{2T}_s}$ Those frequency signals be made as transition band B _tInterior point;

3), satisfy $\frac{1+\mathrm{\&alpha;}}{{2T}_s}<\left|f\right|\&le;B$ Those frequency signals be made as stopband B _sInterior point;

That is, in step 203, determine that according to the sampling period of received signal the pulse-shaping filter is the impulse Response Function of variable with time; The impulse Response Function of determining the pulse-shaping filter then is the transfer function of variable with the frequency; According to the Frequency Response of determining in the transfer function frequency-region signal of received signal is divided into frequency signal in the pulse-shaping filter passband, frequency signal in the transition band and the frequency signal in the stopband again, in concrete the enforcement, when carrying out segmentation, can determine according to frequency signal, sampling period according to Frequency Response.

Because after the transfer function of pulse-shaping filter had been determined, just filtering characteristic was just definite for its frequency response characteristic so, by behind the pulse-shaping filter, the signal that is in different Frequency points just has different decay in received signal.Each filter all has passband, transition band and stopband, the signal that is in the different frequency bands is passed through filter, the amplitude of signal just has very big difference after the filtering through coming out after the Filtering Processing, also based on this, utilize filter response with the received signal segmentation in force, and carried out segmentation filtering.

From as can be known above-mentioned, because the transfer function RC of root raised cosine filter ₀(f) characteristics, the amplitude that is in the frequency signal in passband, transition band and the stopband has very big difference, based on this, when the base band Suppression of narrow band interference is implemented, at first be, the baseband signal x (m) that passes through behind the pulse-shaping filter that will receive in step 201 does the FFT conversion in step 202, obtain the frequency domain signal X (k) of received signal then.

After this in step 203 X (k) is divided into three sections, that part of X (k) in the pulse-shaping filter passband is made as X _p(k), $0\&le;k\&le;\frac{1-\mathrm{\&alpha;}}{{2T}_s};$ The part that is in accordingly in the transition band is made as X _t(k), $\frac{1-\mathrm{\&alpha;}}{{2T}_s}\&le;k\&le;\frac{1+\mathrm{\&alpha;}}{{2T}_s};$ Part in the stopband is X _s(k), $\frac{1+\mathrm{\&alpha;}}{{2T}_s}<k\&le;B.$

Threshold value when again three sections frequency-region signals being carried out Filtering Processing in step 203 is respectively below chosen and is carried out corresponding filtering and describes.

One, to X _p(k) carry out Filtering Processing, that is, the frequency signal in the paired pulses formed filter passband is handled.

In the enforcement, the frequency signal sets thresholding in passband is: Th _p=μ * M _Av, wherein:

M _AvAmplitude equalizing value for all the frequency signals in the passband, specifically can be with the intermediate value of this amplitude equalizing value as frequency signal in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _Av

μ during according to proper communication the spectrum value of signal distribute and choose.μ is a discrepancy factor, and just the amplitude of frequency will be carried out filtering above amplitude intermediate value μ those frequencies doubly.Can being chosen in the enforcement means no harm when disturbing proper communication, can not influence minimum value in those values of the original operate as normal of system by the definite filtering algorithm of setting of μ value as μ.

Concrete, determine 1 for thresholding in passband), can use X _p(k) average of the amplitude of Nei all frequency signals is as the intermediate value M of frequency signal in the passband _Av2), also can be X _p(k) Nei frequency signal is divided into several portions, calculates the average of amplitude of the frequency signal of each part respectively, gets minimum average then as M _Av

Threshold value can be expressed as Th _p=μ * M _Av, then the distribution of choosing generally the spectrum value of signal can be according to proper communication time of μ is got, and generally can get 3～5.

When utilizing thresholding to carry out filtering, for the point in the passband, if amplitude surpasses thresholding Th _p, or be changed to 0, or be changed to a pre-set amplitude, phase place be changed to 0 or keep the phase place of this point and amplitude be changed to predefined value all can, be lower than thresholding Th for amplitude _pGive keep.

Two, to X _t(k) carry out Filtering Processing, that is, the frequency signal in the paired pulses formed filter transition band is handled.

In the enforcement, the frequency signal sets thresholding in transition band is: Th _p=μ * M _Av, wherein:

M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter;

μ during according to proper communication the spectrum value of signal distribute and choose.μ is a discrepancy factor, and just the amplitude of frequency will be carried out filtering above amplitude intermediate value μ those frequencies doubly.Can being chosen in the enforcement means no harm when disturbing proper communication, can not influence minimum value in those values of the original operate as normal of system by the definite filtering algorithm of setting of μ value as μ.

Perhaps, pointwise or set thresholding TH according to the attenuation characteristic segmentation that receives formed filter _t=β * TH _p, TH wherein _pIt is the filter threshold in the passband of setting previously.β is a decay factor, if the situation of thresholding is set in pointwise, β then is the ratio that carries out the frequency domain amplitude in frequency domain amplitude and the passband that receives formed filter of reception formed filter of frequency correspondence of filtering herein; If set the situation of thresholding according to the attenuation characteristic segmentation that receives formed filter, β then is the ratio of the frequency domain amplitude in maximum frequency domain amplitude of carrying out the reception formed filter of frequency correspondence in the section of filtering herein and the passband that receives formed filter.

For X _p(k) the equal application by analogy of but filter processing method is in X _t(k).Because the point in the transition band is the decay that will be subjected to the transition band of pulse-shaping filter, therefore can also be according to the attenuation characteristic segmentation of the transition band of pulse-shaping filter or intermediate value M that the frequency signal is set in pointwise _AvDetermine corresponding thresholding.

Three, to X _s(k) carry out Filtering Processing, that is, the frequency signal in the paired pulses formed filter stopband is handled.

During processing, can directly be changed to 0 or be changed to a value and all can to the amplitude of these frequency signals near 0.

After the filtering, just can execution in step 204, the X after the Filtering Processing (k) is done the IFFT conversion, obtain through baseband signal x (m) after the anti-interference process, suppress to handle thereby finish the base band arrowband.

Based on same inventive concept, the present invention also provides a kind of restraining device of baseband signal narrow band interference, describes below in conjunction with the embodiment of accompanying drawing to this device.

Fig. 4 is the restraining device structural representation of baseband signal narrow band interference, as shown in the figure, can comprise in the restraining device:

Acquisition module 401 is used to obtain the baseband signal of received signal after passing through the pulse-shaping filter;

Conversion module 402 is used for baseband signal is obtained the frequency-region signal of received signal after the FFT conversion;

Filtration module 403 is used for according to the pulse-shaping filter response frequency signal in the pulse-shaping filter passband of frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band being carried out filtering respectively;

Inverse transform module 404 is used for filtered frequency-region signal is obtained the baseband signal of received signal after the IFFT conversion.

In the enforcement, when according to the pulse-shaping filter response frequency-region signal of received signal being carried out segmentation, filtration module can also be further used for determining according to the sampling period of received signal the impulse Response Function of pulse-shaping filter; Determine the transfer function of pulse-shaping filter impulse Response Function; The Frequency Response of determining according to described transfer function is determined frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband in the frequency-region signal of received signal, specifically can determine the scope of segmentation by frequency signal in the transfer function and sampling period.

In the enforcement, the pulse-shaping filter can be selected root raised cosine filter commonly used for use;

Under this scheme, filtration module can also be further used for

Satisfy $0\&le;\left|f\right|\&le;\frac{1-\mathrm{\&alpha;}}{{2T}_s}$ The frequency signal be defined as frequency signal in the passband;

Satisfy $\frac{1-\mathrm{\&alpha;}}{{2T}_s}\&le;\left|f\right|\&le;\frac{1+\mathrm{\&alpha;}}{{2T}_s}$ The frequency signal be defined as frequency signal in the transition band;

Satisfy $\frac{1+\mathrm{\&alpha;}}{{2T}_s}<\left|f\right|\&le;B$ The frequency signal be defined as frequency signal in the stopband;

Wherein: f is a frequency, and α is a rolloff-factor, T _sBe the sampling period of received signal, B is the bandwidth of received signal.

In the enforcement, filtration module carries out filtering after can also being further used for setting thresholding in passband, sets described thresholding and is:

Th _p=μ * M _Av, wherein:

M _AvBe the amplitude equalizing value of all the frequency signals in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _Av

μ during according to proper communication the spectrum value of signal distribute and choose.

After setting thresholding in a manner described, filtration module can be further used for amplitude is surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

In the enforcement, filtration module carries out filtering after can also being further used for setting thresholding in transition band, sets thresholding and is:

Th _p=μ * M _Av, wherein:

M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter;

μ during according to proper communication the spectrum value of signal distribute and choose.

After setting thresholding, amplitude can be surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

In the enforcement, filtration module can also be further used for the amplitude of the frequency signal in the stopband is changed to 0, perhaps is changed to the value near 0.

Owing to be based on same inventive concept with the inhibition method of baseband signal narrow band interference, therefore, the principle and the used technological means of dealing with problems described in can reference method in the implementation process of device.

From the foregoing description as can be seen, the present invention is when being applied to the Suppression of narrow band interference of base band, characteristics according to the received pulse formed filter, the frequency band of received signal is divided into passband, transition band and stopband, and adopt different thresholdings to suppress narrow band interference with different treating methods to the frequency signal in these 3 different frequency bands, thereby overcome the frequency signal of not considering in the prior art in the pulse-shaping filter passband, the frequency signal in the transition band and the intensity of the frequency signal in the stopband are the deficiencies that very big difference is arranged, thereby have improved the Suppression of narrow band interference ability of communication system.

Further, determine the signal intermediate value according to the attenuation characteristic segmentation or the pointwise of the transition band that receives formed filter, and then the filter threshold of definite transition band, thereby better filter effect can in transition band, be obtained.

Further, the amplitude of the frequency signal in the stopband is directly put 0 or be made as one very near 0 value, thereby can in stopband, obtain better filter effect.

Taken into full account the spectral characteristic of signal in the invention process by the received pulse formed filter, frequency range to signal adopts different thresholdings to suppress narrow band interference with different treating methods, compare with the Suppression of narrow band interference algorithm that adopts same thresholding and same treating method, can improve the Suppression of narrow band interference ability of communication system after the invention process.

Simultaneously,, therefore can use DSP (Data Signal Processor, data signal processor) to realize very easily, make and realize that cost is very low because the embodiment of the invention is the inhibition of base band to be disturbed handle.Particularly, can realize Suppression of narrow band interference by upgrading DSP, not need to carry out the modification of hardware in base band for the mobile communication system of not considering in the past Anti-interference Design.

Those skilled in the art should understand that embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt complete hardware embodiment, complete software implementation example or in conjunction with the form of the embodiment of software and hardware aspect.And the present invention can adopt the form that goes up the computer program of implementing in one or more computer-usable storage medium (including but not limited to magnetic disc store, CD-ROM, optical memory etc.) that wherein include computer usable program code.

The present invention is that reference is described according to the flow chart and/or the block diagram of method, equipment (system) and the computer program of the embodiment of the invention.Should understand can be by the flow process in each flow process in computer program instructions realization flow figure and/or the block diagram and/or square frame and flow chart and/or the block diagram and/or the combination of square frame.Can provide these computer program instructions to the processor of all-purpose computer, special-purpose computer, Embedded Processor or other programmable data processing device to produce a machine, make the instruction of carrying out by the processor of computer or other programmable data processing device produce to be used for the device of the function that is implemented in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame appointments.

These computer program instructions also can be stored in energy vectoring computer or the computer-readable memory of other programmable data processing device with ad hoc fashion work, make the instruction that is stored in this computer-readable memory produce the manufacture that comprises command device, this command device is implemented in the function of appointment in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame.

These computer program instructions also can be loaded on computer or other programmable data processing device, make on computer or other programmable devices and to carry out the sequence of operations step producing computer implemented processing, thereby the instruction of carrying out on computer or other programmable devices is provided for being implemented in the step of the function of appointment in flow process of flow chart or a plurality of flow process and/or square frame of block diagram or a plurality of square frame.

Although described the preferred embodiments of the present invention, in a single day those skilled in the art get the basic creative notion of cicada, then can make other change and modification to these embodiment.So claims are intended to all changes and the modification that are interpreted as comprising preferred embodiment and fall into the scope of the invention.

Claims (12)

1, a kind of inhibition method of baseband signal narrow band interference is characterized in that, comprises the steps:

Obtain the baseband signal of received signal after passing through the pulse-shaping filter;

Baseband signal is obtained the frequency-region signal of received signal after fast fourier transform;

According to the pulse-shaping filter response frequency signal in the pulse-shaping filter passband in the described frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band are carried out filtering respectively;

Filtered frequency-region signal is obtained the baseband signal of received signal behind invert fast fourier transformation.

2, the method for claim 1 is characterized in that, determines frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband in the frequency-region signal, is specially:

Determine the impulse Response Function of pulse-shaping filter according to the sampling period of received signal;

Determine the transfer function of the impulse Response Function of pulse-shaping filter;

The Frequency Response of determining according to described transfer function determines that the frequency-region signal of received signal is frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband.

3, method as claimed in claim 2 is characterized in that, described pulse-shaping filter is a root raised cosine filter;

Frequency signal in the pulse-shaping filter passband in described definite frequency-region signal, the frequency signal in the transition band and the frequency signal in the stopband are specially:

Satisfy $0\&le;\left|f\right|\&le;\frac{1-a}{2T_s}$ The frequency signal be frequency signal in the passband;

Satisfy $\frac{1-a}{2T_s}\&le;\left|f\right|\&le;\frac{1+a}{2T_s}$ The frequency signal be frequency signal in the transition band;

Satisfy $\frac{1+a}{2T_s}<\left|f\right|\&le;B$ The frequency signal be frequency signal in the stopband;

Wherein: f is a frequency, and α is a rolloff-factor, T _sBe the sampling period of received signal, B is the bandwidth of received signal.

4, as the arbitrary described method of claim 1 to 3, it is characterized in that, described frequency signal in the passband carried out filtering, be specially:

The setting filter threshold is: Th _p=μ * M _Av, wherein: M _AvBe the amplitude equalizing value of all the frequency signals in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _AvThe μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time;

Amplitude is surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

5, as the arbitrary described method of claim 1 to 3, it is characterized in that, described frequency signal in the transition band carried out filtering, be specially:

The setting thresholding is: Th _p=μ * M _Av, or, setting thresholding TH according to the attenuation characteristic segmentation that receives formed filter _t=β * TH _p, wherein: M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter; The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time; TH _pBe the filter threshold in the passband, β is the decay factor of determining according to the ratio of the frequency domain amplitude in the passband of the frequency domain amplitude of the reception formed filter of the frequency signal correspondence of carrying out filtering and reception formed filter;

The amplitude that amplitude is surpassed the frequency signal of thresholding is changed to 0, or is changed to predefined amplitude; The reservation amplitude is lower than the amplitude of the frequency signal of thresholding.

6, as the arbitrary described method of claim 1 to 3, it is characterized in that, described frequency signal in the stopband carried out filtering, be specially:

The amplitude of the frequency signal in the stopband is changed to 0, perhaps is changed to value near 0.

7, a kind of restraining device of baseband signal narrow band interference is characterized in that, comprising:

Acquisition module is used to obtain the baseband signal of received signal after passing through the pulse-shaping filter;

Conversion module is used for baseband signal is obtained the frequency-region signal of received signal after fast fourier transform;

Filtration module is used for according to the pulse-shaping filter response frequency signal in the pulse-shaping filter passband of frequency-region signal, frequency signal and the frequency signal in the stopband in the transition band being carried out filtering respectively;

Inverse transform module is used for filtered frequency-region signal is obtained the baseband signal of received signal behind invert fast fourier transformation.

8, device as claimed in claim 7 is characterized in that, described filtration module is further used for determining according to the sampling period of received signal the impulse Response Function of pulse-shaping filter; Determine the transfer function of pulse-shaping filter impulse Response Function; The Frequency Response of determining according to described transfer function is determined frequency signal, the frequency signal in the transition band and the frequency signal in the stopband in the pulse-shaping filter passband in the frequency-region signal.

9, device as claimed in claim 8 is characterized in that, described pulse-shaping filter is a root raised cosine filter;

Described filtration module be further used for

Satisfy $0\&le;\left|f\right|\&le;\frac{1-a}{2T_s}$ The frequency signal be defined as frequency signal in the passband;

Satisfy $\frac{1-a}{2T_s}\&le;\left|f\right|\&le;\frac{1+a}{2T_s}$ The frequency signal be defined as frequency signal in the transition band;

Satisfy $\frac{1+a}{2T_s}<\left|f\right|\&le;B$ The frequency signal be defined as frequency signal in the stopband;

Wherein, F is a frequency, and α is a rolloff-factor, T _sBe the sampling period of received signal, B is the bandwidth of received signal.

As the arbitrary described device of claim 7 to 9, it is characterized in that 10, described filtration module carries out filtering after being further used for setting thresholding in passband, set described thresholding and be: Th _p=μ * M _Av, wherein:

M _AvBe the amplitude equalizing value of all the frequency signals in the passband, or, the frequency signal in the passband is divided into several portions, calculate the average of amplitude of the frequency signal of each part respectively, get minimum average then as M _AvThe μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time;

After setting described thresholding, amplitude is surpassed thresholding Th _pThe amplitude of frequency signal be changed to 0, or be changed to predefined amplitude; The reservation amplitude is lower than thresholding Th _pThe amplitude of frequency signal.

As the arbitrary described device of claim 7 to 9, it is characterized in that 11, described filtration module carries out filtering after being further used for setting thresholding in transition band, set thresholding and be: Th _p=μ * M _Av,, or, setting thresholding TH according to the attenuation characteristic segmentation that receives formed filter _t=β * TH _p, wherein: M _AvBe the intermediate value of setting according to the attenuation characteristic segmentation or the pointwise of the transition band of filter; The μ discrepancy factor that the spectrum value of signal distributes and chooses for according to proper communication the time; TH _pBe the filter threshold in the passband, β is the decay factor of determining according to the ratio of the frequency domain amplitude in the passband of the frequency domain amplitude of the reception formed filter of the frequency signal correspondence of carrying out filtering and reception formed filter;

After setting described thresholding, the amplitude that amplitude is surpassed the frequency signal of thresholding is changed to 0, or is changed to predefined amplitude; The reservation amplitude is lower than the amplitude of the frequency signal of thresholding.

As the arbitrary described device of claim 7 to 9, it is characterized in that 12, described filtration module is further used for the amplitude of the frequency signal in the stopband is changed to 0, perhaps is changed to the value near 0.

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