CN105827274A - Interference suppression method and system of wireless signal - Google Patents

Abstract

The invention provides an interference suppression method and system of a wireless signal, wherein the method and system are applied to an SC-FDMA wireless spread spectrum communication system. The method comprises: a local frequency-domain pilot frequency sequence is generated; according to the local frequency-domain pilot frequency sequence, LS frequency-domain channel estimation is carried out on a frequency domain response corresponding to a channel discrete time-domain response of an SC-FDMA wireless spread spectrum communication system to obtain a first channel frequency domain response; time-domain noise reduction processing based on channel-PDP-based decision criterion is carried out on the first channel frequency domain response, thereby obtaining a second channel frequency domain response; soft-threshold-based interference detection is carried out on the first channel frequency domain response to obtain a sub channel interference position identifier; mask interference suppression is carried out on the second channel frequency domain response according to the sub channel interference position identifier, thereby obtaining a third channel frequency domain response; and then frequency-domain channel equalization is carried out on the third channel frequency domain response. According to the invention, the influence on the communication system by noises is reduced; the power spectral component of the interference is suppressed effectively; and the influence on the communication system by the interference is eliminated.

Description

The disturbance restraining method of a kind of wireless signal and system

Technical field

The present invention relates to a kind of communication technology, particularly relate to a kind of SC-FDMA (Single-carrier Frequency-Division Multiple Access, single-carrier frequency division multiple access) wireless communication in spread spectrum radio communications system Number disturbance restraining method and system.

Background technology

Since 21 century, aviation aircraft, unmanned air vehicle technique quickly grow, aviation radio spread spectrum communication electromagnetic interference environment More complicated, the requirement in terms of anti-interference index is more and more higher, and related communication field has for the research of this respect the most very much It is worth.

Traditional channel estimation and equalization technology can compensate the Complex Channel impact on system to a certain extent.Mesh Before, apply more channel estimation and equalization technology to include: channel estimation in frequency domain algorithm based on pilot frequency sequence and based on conversion The channel estimation method in territory.Wherein, channel estimation in frequency domain algorithm based on pilot frequency sequence includes least square (Least Square, LS) channel estimation method, the channel of least mean-square error (Minimum Mean Square Error, MMSE) estimates Calculating method and the channel of linear MMSE criterion (Linear Minimum Mean Square Error, LMMSE) Algorithm for estimating；Channel estimation method based on transform domain includes discrete Fourier transform (Discrete Fourier Transform, DFT) channel estimation method and single-carrier frequency division multiple access (Single Carrier Frequency-Division Multiple Access, SC-FDMA) channel estimation method.

Although, channel estimation and equalization technology can compensate the Complex Channel interference to signal to a certain extent, but passes The single-carrier frequency-domain estimation of system and the balancing technique performance under the complicated electromagnetic interference environment such as single-frequency, arrowband interference is relatively Difference.Further, it is wider that special space flight spread spectrum radio communications system takies frequency range, and radio environment often exists the electronic countermeasure of complexity Interference, as high-power single-frequency or arrowband disturb, cannot by traditional channel estimation and equalization technology for simple The electromagnetic interference that antagonism is complicated.

Summary of the invention

The shortcoming of prior art in view of the above, it is an object of the invention to provide the AF panel of a kind of wireless signal Method and system, for solving channel estimation and equalization skill traditional in SC-FDMA spread spectrum radio communications system in prior art Art cannot effectively solve the complicated electromagnetic interference problem on the impact of system.

For achieving the above object and other relevant purposes, the present invention provides the disturbance restraining method of a kind of wireless signal, should For SC-FDMA spread spectrum radio communications system, the disturbance restraining method of described wireless signal includes: generate local pilot tone sequence Row；According to the described local frequency-domain pilot sequence channel dispersion time domain response pair to described SC-FDMA spread spectrum radio communications system The frequency domain response answered carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；Described first channel frequency domain response is entered The time domain noise reduction of row decision rule based on channel PDP processes, it is thus achieved that second channel frequency domain response；And to described first channel frequency Domain response carries out Interference Detection based on soft-threshold, it is thus achieved that subchannel interference position identifies；To described second channel frequency domain response Carry out mask AF panel according to described subchannel interference position mark, obtain the 3rd channel frequency domain response；To described 3rd letter Road frequency domain response carries out frequency domain channel equalization.

In one embodiment of the invention, described local frequency-domain pilot sequence is by being expanded by orthogonal variable by frequency pilot sign Frequently factor spread spectrum, and carry out scrambling by GOLD sequence and generate.

In one embodiment of the invention, described Orthogonal Variable Spreading Factor OVSF uses the Walsh sequence of a length of 1024.

In one embodiment of the invention, described second channel frequency domain response is first by described first channel frequency domain response warp Cross IDFT conversion, be converted to the first channel time domain response of time domain；Decision rule based on channel PDP is carried out at time domain noise reduction again Reason obtains second channel time domain response, eventually passes through DFT transform and generates to frequency domain；Wherein, judgement based on channel PDP is accurate It is thenIn formula, h_optRepresent described second channel time domain response；Represent described first Channel time domain responds；P_LSAlong composing when representing the time-domain power of LS channel estimation in frequency domain, ρ represents power spectrum threshold value.

In one embodiment of the invention, described power spectrum threshold value ρ is by the average merit of described local frequency-domain pilot sequence Rate and noise power determine.

In one embodiment of the invention, described subchannel interference position mark is to calculate detection statistic, and according to estimating Meter signal noise ratio level, chooses the detection threshold of correspondence；Described detection statistic is compared with described detection threshold and generates 's；Wherein, described subchannel interference position is designated0≤k≤N-1；U represents described Detection statistic, and0≤k≤N-1, H₁Represent described first channel frequency domain response；V represents described Detection threshold.

In one embodiment of the invention, described 3rd channel frequency domain response is by described second channel frequency domain response foundation Described subchannel interference position mark carries out mask AF panel and obtains: 0≤k≤N-1；Wherein, H_cRepresent described 3rd channel frequency domain response；H₂Represent described second channel frequency domain response.

In one embodiment of the invention, the described step that described 3rd channel frequency domain response is carried out frequency domain channel equalization It is to use frequency domain channel equalization algorithm based on MMSE criterion to realize.

The invention also discloses the Interference Suppression System of a kind of wireless signal, be applied to SC-FDMA radio spread spectrum communication system System, the suppression system of described wireless signal includes: pilot frequency sequence generation module, is used for generating local frequency-domain pilot sequence；Channel Estimation module, for according to the described local frequency-domain pilot sequence shock response to described SC-FDMA spread spectrum radio communications system Corresponding frequency response function carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；Time domain noise reduction and interference detection module, For described first channel frequency domain response being carried out time domain noise reduction process and Interference Detection, and obtain second channel frequency domain response and Subchannel interference position identifies；AF panel module, for disturbing according to described subchannel described second channel frequency domain response Station location marker carries out mask AF panel, obtains the 3rd channel frequency domain response；Channel equalization module, for described 3rd channel Frequency domain response carries out frequency domain channel equalization.

In one embodiment of the invention, described time domain noise reduction and interference detection module include: time domain noise reduction submodule is used Process in the time domain noise reduction that described first channel frequency domain response is carried out decision rule based on channel PDP, obtain described second Channel frequency domain response；Interference Detection submodule, for carrying out interference based on soft-threshold inspection to described first channel frequency domain response Survey, generate described subchannel interference position mark.

In one embodiment of the invention, decision rule based on channel PDP is In formula, h_optRepresent second channel time domain response；Represent the first channel time domain sound that described first channel frequency domain response is corresponding Should；P_LSAlong composing when representing the time-domain power of LS channel estimation in frequency domain, ρ represents power spectrum threshold value；And described power spectrum threshold value ρ Mean power and noise power by described local frequency-domain pilot sequence determine.

In one embodiment of the invention, described Interference Detection submodule is by calculating detection statistic, and by described Detection statistic and detection threshold compare and generate described subchannel interference position mark, and wherein, described subchannel is done Disturbing station location marker is0≤k≤N-1；In formula, U represents described detection statistic, and0≤k≤N-1, in formula, H₁Represent described first channel frequency domain response；V_d-highRepresent described detection Thresholding.

In one embodiment of the invention, described channel equalization module uses frequency domain channel equalization based on MMSE criterion to calculate Method carries out frequency domain channel equalization to described 3rd channel frequency domain response.

As it has been described above, the disturbance restraining method of a kind of wireless signal of the present invention and system, it is applied to the wireless expansion of SC-FDMA Frequently communication system.The present invention has combined closely channel estimation in frequency domain technology and frequency domain channel equalization communication technology, i.e. to channel from Scattered time domain response adds time domain noise reduction based on PDP decision rule and processes and the step of Interference Detection based on soft-threshold.Phase Than traditional based on maximum delay L_maxTime domain suppression Noise Method, based on PDP judgement time domain noise reduction process can be further Reduce the noise impact on system；Being simultaneous for specific single-frequency, the environment of arrowband electromagnetic interference, strong jamming based on soft threshold values is examined Survey processes can be with Auto-Sensing certain interference frequency range, and the soft threshold values detection grounds of judgment of improvement estimates that signal to noise ratio chooses door Limit, suppresses the power spectrum component of interference effectively, eliminates the interference impact on system.

Accompanying drawing explanation

Fig. 1 is shown as the schematic flow sheet of the disturbance restraining method of a kind of wireless signal disclosed in the embodiment of the present invention.

Fig. 2 is shown as the local pilot tone in the disturbance restraining method of a kind of wireless signal disclosed in the embodiment of the present invention The generation of sequence and multiplexing structure schematic diagram.

Fig. 3 is shown as the antijam communication in the disturbance restraining method of a kind of wireless signal disclosed in the embodiment of the present invention Module diagram.

Fig. 4 is shown as the based on channel PDP of the disturbance restraining method of a kind of wireless signal disclosed in the embodiment of the present invention The performance curve schematic diagram of the time domain noise reduction of decision rule.

Fig. 5 is shown as the jamproof property of the single-frequency of the disturbance restraining method of a kind of wireless signal disclosed in the embodiment of the present invention Can curve synoptic diagram.

Fig. 6 is shown as the structural representation of the Interference Suppression System of a kind of wireless signal disclosed in basic inventive embodiments.

Element numbers explanation

S10～S50 step

610 pilot frequency sequence generation modules

620 channel estimation modules

630 time domain noise reductions and interference detection module

631 time domain noise reduction submodules

632 Interference Detection submodules

640 AF panel modules

650 channel equalization module

Detailed description of the invention

Below by way of specific instantiation, embodiments of the present invention being described, those skilled in the art can be by this specification Disclosed content understands other advantages and effect of the present invention easily.The present invention can also be by the most different concrete realities The mode of executing is carried out or applies, the every details in this specification can also based on different viewpoints and application, without departing from Various modification or change is carried out under the spirit of the present invention.It should be noted that, in the case of not conflicting, following example and enforcement Feature in example can be mutually combined.

Refer to accompanying drawing.It should be noted that the diagram provided in following example illustrates this most in a schematic way Bright basic conception, the most graphic in component count time only display with relevant assembly in the present invention rather than is implemented according to reality, Shape and size are drawn, and during its actual enforcement, the kenel of each assembly, quantity and ratio can be a kind of random change, and its assembly Layout kenel is likely to increasingly complex.

The disturbance restraining method of a kind of wireless signal of the present invention and system are with equal at channel estimation in frequency domain of combining closely Under the basis of weighing apparatus communication technology, a kind of channel with relatively strong anti-interference ability of proposition estimates the system with channel equalization.This Invention uses the time domain suppression noise skill of decision rule based on channel PDP (Power Delay Profile, power-delay is composed) Art suppression class white noise interference, such as the noise jamming such as AWGN, sea clutter；Use interference detection technique based on soft threshold values, coordinate Mask AF panel, further suppress the interference of single-frequency and arrowband.

Embodiment 1

Present embodiment discloses the AF panel side of a kind of wireless signal being applied to SC-FDMA spread spectrum radio communications system Method, is used for suppressing noise, and solves the interference to system of feature single-frequency or arrowband.

As it is shown in figure 1, the disturbance restraining method of the wireless signal of the present embodiment includes:

Step S10, generates local frequency-domain pilot sequence；

The generation of the local pilot tone of the present embodiment be with reference to CDMA (Code Division Multiple Access, CDMA) pilot tone generate mentality of designing, the most as shown in Figure 2.Frequency pilot sign p passes through OVSF (Orthogonal Variable Spreading Factor, Orthogonal Variable Spreading Factor OVSF) it is multiplexed in data signal after spread spectrum.Use CDMA Pilot tone generate mentality of designing, the local frequency-domain pilot sequence of generation will not the time interval resource of temporary independence, simplify frame structure.

As in figure 2 it is shown, frequency pilot sign p is spread by the Walsh sequence of a length of 1024, carried out by Gold sequence Scrambling obtains.Wherein, for the Gold sequence a length of 1024 of scrambling, and use LTE (Long Term Evolution, length Phase evolution) generator polynomial in agreement generates.The composite symbol after Gold sequence scrambles, pass through after adding single carrier DFT-S-OFDM (Discrete Fourier Transform-Spread OFDM, the orthogonal frequency of discrete Fourier transform spread spectrum Point multiplexing multiple access technique) technology realizes single carrier communication, and after inserting cyclic prefix CP (Cyclic Prefix), feeding is penetrated Frequently front end.

In the present embodiment, frequency pilot sign p=(1+i)/2, after the Walsh sequence spread spectrum of a length of M, then through long After the Gold sequence scrambling that degree is M, then it is multiplied by the local frequency-domain pilot sequence of power factor b acquisition.

Step S20, according to described local frequency-domain pilot sequence to the channel of described SC-FDMA spread spectrum radio communications system from The frequency domain response dissipating time domain response corresponding carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response.

After generating local frequency-domain pilot sequence, use the LS channel estimation in frequency domain frequency domain to high intensity at a wireless receiver Interference is tracked, analyzes and suppresses.Being analyzed by the result of LS channel estimation in frequency domain, detection single-frequency, arrowband interference exist The distribution situation of frequency domain channel；LS frequency domain estimated result is transformed to time domain simultaneously, choose channel maximum path time delay corresponding Tap is windowed thresholding as the suppression of time domain white noise.In conjunction with channel estimation and equalization technology, the present embodiment concrete anti-interference Structure as shown in Figure 3.

The digital front-end output data of wireless receiver are accorded with by the single carrier after lock unit and removal cyclic prefix CP NumberWherein M is the sampling point number of a discrete single-carrier symbol.

As it is shown on figure 3, signal y (n) after channel and removal cyclic prefix CP of the present embodiment represents received The discrete single-carrier symbol of individual time domain, wherein,0≤n≤M-1；Wherein, h (n) is letter Road discrete time-domain response；X (n) is for launching discrete symbols；W (n) represents discrete and independent white Gaussian noise；Symbol represents volume Long-pending computing.Further, channel dispersion time domain responseA in formula_lRepresenting the gain in path, l represents and does not goes the same way Footpath time delay, L represents channel maximum path CIR (Channel Impulse Response, channel impulse response).At the present embodiment In, the discrete single-carrier symbol of a time domain has 2048 sampling points, i.e. M=2048.

Further, the present embodiment uses LS channel estimation in frequency domain, therefore, channel dispersion time domain response need to be converted to letter The response of road discrete frequency domain, i.e. to the discrete single carrier of a time domain through DFT (Discrete Fourier Transform, discrete Fourier transform), the frequency domain data through DFT transform is carried out subcarrier demapping, then kth simultaneously The frequency domain output of subcarrier can be expressed as: Y (k)=X (k) H (k)+W (k), 0≤k≤N-1；Wherein, X represents the discrete symbol of transmission Number frequency domain response, W (k) represent white Gaussian noise frequency domain response, H (k) represents channel dispersion frequency domain response, and N represents frequency domain Frequency domain number of samples after subcarrier demapping.

Carry out channel estimation in frequency domain by LS criterion, obtain channel according to a preliminary estimate after the first channel frequency domain response be:

$H_1\left(k\right)=\frac{Y\left(k\right)}{P\left(k\right)}=H\left(k\right)+\frac{W\left(k\right)}{P\left(k\right)},0\≤k\≤N-1;---\left(1\right)$

Wherein, Y (k) is for receiving discrete single-carrier symbol frequency domain response, and P (k) is local frequency-domain pilot sequence.

Step S30, is carried out at the time domain noise reduction of decision rule based on channel PDP described first channel frequency domain response Reason, it is thus achieved that second channel frequency domain response；And described first channel frequency domain response is carried out Interference Detection based on soft-threshold, it is thus achieved that Subchannel interference position identifies.

From formula (1), it is not difficult to find out, after LS channel estimation in frequency domain, still there is the biggest noise jamming.Therefore one As use, in time domain, the first channel frequency domain response carried out noise reduction process.

Therefore, first the first channel frequency domain response is carried out IDFT (InverseDiscreteFourierTransform, Inverse discrete Fourier transform) conversion, obtain the first channel time domain response that the first channel frequency domain response is correspondingThat is:

At present, owing to most CIR energy concentrates in L tap of first few, so the more commonly used is to pass through Noise power outside zeroization channel tap, so can the interference shadow to system of a certain degree of minimizing white noise character Ringing, wherein, the interference with white noise character includes the free space noise of Gaussian distributed, and Rayleigh distributed and The sea clutter interference of logarithm normal distribution.It is therefore assumed that the channel impulse response tap length of maximum is L_max, then press down through noise Time domain channel response after system is:

$h_2\left(n\right)=\left\{\begin{array}{cc}{\hat{h}}_{LS}\left(n\right),& 0\≤n\≤L_{max}\\ 0,& n\≥L_{max}\end{array}\right.;$

Wherein, L_max=L_τ+S；L_τMaximum multipath time delay under the channel circumstance of expression system, S represents signal transmitted bandwidth, And time domain noise suppression algorithm generally to choose maximum delay value be CP length.From above-mentioned decision rule it can be seen that many at present channel Footpath time delay is less than L_maxTime, choose fixing channel delay response threshold and often introduce more noise.Secondly, when multipath Prolong more severe, the when that i.e. maximum multipath time delay value being bigger, such as severe urban district channel model, due to the letter in relatively long time delay footpath Number Energy distribution proportion is the least, chooses the L of maximum_maxAs decision threshold, although obtain more Delay, but equally Inevitably introduce more noise.

Comprehensive problem above, the present embodiment proposes the time domain noise reduction of the decision rule based on channel PDP of improvement and processes, Wherein, decision rule based on channel PDP is expressed as:

In formula, h_optN () is second channel time domain response, P_LSN () is the time-domain power delay profile of LS channel estimation in frequency domain, ρ For power spectrum threshold value, the value size of power spectrum threshold value ρ is decided by the mean power of local frequency-domain pilot sequence, i.e.Wherein, E [| P (k) |²] represent the mean power of local frequency-domain pilot sequence,Represent the noise of scene Power.

Again to second channel time domain response h_optN () carries out DFT transform, thus obtain second channel frequency domain response H₂(k)。

Further, the mean power of local frequency-domain pilot sequence is:

E[|P(k)|²]=b E [| Y_i(k)|²]； (3)

In formula, b is the pilot power factor, owing to receiving signal y_iN () power is modulated to unit 1, can obtain according to above formula Power to ground frequency-domain pilot sequence is b.Noise power is expressed as:

${{\widehat{\mathrm{\σ}}}_n}^2=\frac{1}{N-L_{max}}\underset{n=L_{max}}{\overset{N}{\Σ}}|{\hat{h}}_{LS}\left(n\right){|}^2.---\left(4\right)$

Further, the present embodiment is for the AF panel in the environment of realizing for different signal to noise ratios, it is also proposed that right First channel frequency domain response Interference Detection based on soft-threshold.It uses different doors under high s/n ratio and low signal-to-noise ratio environment Limit value carries out AF panel, such that it is able to improve the AF panel performance in the case of low signal-to-noise ratio.Choose specified threshold V, Set detection statistic U the first channel frequency domain response obtained after LS channel estimation in frequency domain is detected and adjudicated, from And obtain the subchannel interference position mark of the frequency domain physical straton of single-frequency, arrowband interference:

Wherein, the calculation expression of detection statistic is:

$U\left(k\right)=\frac{\left|H_1\left(k\right)\right|}{\frac{1}{N}\underset{n=0}{\overset{N-1}{\Σ}}\left|H_1\left(n\right)\right|},0\≤k\≤N-1.---\left(6\right)$

In formula, H₁K () represents the first channel frequency domain response.

In the present embodiment, in the environment of channel is in high s/n ratio, i.e. SNR_est> 0dB, set detection threshold as V_d-high, detection statistic U is analyzed, the strong jamming subchannel higher than threshold value is distinguish between, it is determined that rule is:

In like manner, in the environment of channel is in low signal-to-noise ratio, use low signal-to-noise ratio detection threshold V_d-low, interference is examined Survey judgement.If sc_index (k) is that subchannel interference position mark current sub-channel statistic is more than thresholding, then labelling 0 in formula, Otherwise labelling 1.

Step S40, carries out mask interference to described second channel frequency domain response according to described subchannel interference position mark Suppression, obtains the 3rd channel frequency domain response.

The subchannel interference position obtained is identified the sc_index condition as quick AF panel, obtains after suppression interference The 3rd channel frequency domain response:

$H_c\left(k\right)=\left\{\begin{array}{cc}{H}_2\left(k\right),& sc\_index\left(k\right)=1\\ 0,& sc\_index\left(k\right)=0\end{array}\right.,0\≤k\≤N-1.---\left(7\right)$

Step S50, carries out frequency domain channel equalization to described 3rd channel frequency domain response.

The present invention uses frequency domain equalization, to avoid the matrix operations of complexity, based on existing efficient IP kernel algoritic module, effectively Ground reduces the implementation complexity of channel equalization.Frequency domain channel equalization algorithm based on MMSE criterion can be expressed as:

$Y_o\left(k\right)=\frac{Y_i\left(k\right)\·H_c^{*}\left(k\right)}{|H_c\left(k\right){|}^2+\frac{1}{{\mathrm{SNR}}_{est}}},0\≤k\≤N-1.---\left(8\right)$

Wherein, SNR_estIt is the estimation signal to noise ratio currently receiving symbol, Y_oK () is that discrete data symbol is defeated after equilibrium The frequency domain response gone out, Y_iK () is the input frequency domain response of discrete data symbol,For H_cThe complex conjugate of (k).Further, by public affairs Formula (3) and formula (4), estimate signal to noise ratio snr_estCan be expressed as:

${\mathrm{SNR}}_{est}=\frac{E\[|P\left(k\right){|}^2\]}{{{\widehat{\mathrm{\σ}}}_n}^2}=\frac{b(N-L)}{\underset{n=L}{\overset{N}{\Σ}}|{\hat{h}}_{LS}\left(n\right){|}^2}.$

It should be noted that the step of above method divides, be intended merely to describe clear, it is achieved time can merge into one Step or split some step, is decomposed into multiple step, as long as comprising identical logical relation, all at this patent In protection domain；To adding inessential amendment in algorithm or in flow process or introducing inessential design, but do not change Become the core design of its algorithm and flow process all in the protection domain of this patent.

Further, noise suppressed and single-frequency in order to verify the disturbance restraining method of the wireless signal of the present embodiment are anti-dry Immunity energy, uses Matlab instrument to build system simulation platform, and is analyzed simulation result.This emulation be for SC-FDMA spread spectrum radio communications system, carry out in awgn channel model and fading channel model respectively time domain noise reduction performance and AF panel performance is carried out.Wherein, the relevant configured parameter of SC-FDMA spread spectrum radio communications system refers to table 1 below；Decline letter Road model uses typical rural area model (cost207RAx6) channel model, and its parameter configuration refers to table 2 below.

Table 1 system relevant configured parameter

Table 2 typical rural area fading channel parameter

Further, the SC-FDMA spread spectrum radio communications system of this emulation also suffers from mono-tone interference.Mono-tone interference is to instigate With the interference signal of single sine wave or multiple sine wave.This emulation is in the signal bandwidth of 7.68MHz, follows each Ring single-carrier symbol, produces the interference that a frequency is random, and superposition is on this symbol, and the power of interference presets.This is imitated Genuine interference model is:Wherein, I is interference signal, and f is The frequency values of the interference randomly generated, k is data point sequence number, f_s=15.36MHz, represents system sampling frequency；BW= 7.68MHz, represents signal bandwidth.

The emulation of time domain noise reduction performance is the emulation different signal to noise ratio (Signal-to-Noise before and after noise reduction process Ratio, SNR) LS estimate least mean-square error (Mean Square Error, MSE).Further, in order to verify that the present embodiment carries The performance that the time domain noise reduction gone out processes, the emulation of this time domain noise reduction performance is respectively in awgn channel model and fading channel model Under carry out, be respectively adopted the time domain of the decision rule based on channel PDP of the fixing CIR time delay window noise reduction of tradition and the present embodiment Noise reduction.The simulation result of this time domain noise reduction performance is as shown in Figure 4.Can be it has been observed that believe at AWGN by contrast from Fig. 4 In the environment of road model and typical fading channel model, use the decision rule based on channel PDP of the present embodiment proposition Time domain noise reduction processes more excellent to the inhibition of white noise.

The emulation of single-frequency interference free performance is the numerical value of emulation bit error rate under different signal interference ratios.Further, in order to The performance of the anti-interference process that checking the present embodiment proposes, simulates the bit error rate through the present embodiment anti-interference process respectively Curve chart and the errored bit without the present embodiment anti-interference process (Interference Detection based on soft-threshold and mask AF panel) Rate curve chart, to facilitate contrast.The simulation result of this interference free performance is as shown in Figure 5.Can be observed by contrast from Fig. 5 Find, be 10 in the bit error rate^-3During level, after the single-frequency anti-interference process (I-Cancellation) of the present embodiment, system Performance has the gain of 8.6dB.

Embodiment 2

Present embodiment discloses the Interference Suppression System of a kind of wireless signal, be applied to SC-FDMA radio spread spectrum communication system System.The Interference Suppression System of the wireless signal of the present embodiment is mainly used in suppressing noise, and solves feature single-frequency or arrowband to being The interference of system.

As shown in Figure 6, the Interference Suppression System of the wireless signal of the present embodiment includes:

Pilot frequency sequence generation module 610, is used for generating local frequency-domain pilot sequence.Pilot frequency sequence generation module 610 reference The mentality of designing that the pilot tone of CDMA (Code Division Multiple Access, CDMA) generates is concrete such as Fig. 2 institute Show.Frequency pilot sign p is expanded by OVSF (Orthogonal Variable Spreading Factor, Orthogonal Variable Spreading Factor OVSF) It is multiplexed in data signal after Pin.The pilot tone using CDMA generates mentality of designing, and the local frequency-domain pilot sequence of generation will not The time interval resource of temporary independence, simplifies frame structure.

Channel estimation module 620, is used for according to described local frequency-domain pilot sequence described SC-FDMA radio spread spectrum communication The frequency response function that the shock response of system is corresponding carries out LS channel estimation in frequency domain, generates the first channel frequency domain response:

The discrete single-carrier symbol of the time domain received is carried out DFT transform, thus obtains channel dispersion frequency domain Response H (k)；Again by carrying out channel estimation in frequency domain by LS criterion, obtain channel according to a preliminary estimate after first channel frequency ring Should be:

$H_1\left(k\right)=\frac{Y\left(k\right)}{P\left(k\right)}=H\left(k\right)+\frac{W\left(k\right)}{P\left(k\right)},0\≤k\≤N-1;---\left(1\right)$

Wherein, Y (k) is for receiving discrete single-carrier symbol frequency domain response, and P (k) is local frequency-domain pilot sequence.

Time domain noise reduction and interference detection module 630, for carrying out time domain noise reduction process to described first channel frequency domain response And Interference Detection, and generate second channel frequency domain response and subchannel interference position mark.

Wherein, time domain noise reduction and interference detection module 630 include time domain noise reduction submodule 631 and Interference Detection submodule 632:

Time domain noise reduction submodule 631 is for carrying out decision rule based on channel PDP to described first channel frequency domain response Time domain noise reduction process, obtain described second channel frequency domain response:

First, the first channel frequency domain response is carried out IDFT conversion, obtain the first channel frequency domain response H₁(k) corresponding the One channel time domain response

Secondly, then to the first channel time domain respondCarry out at the time domain noise reduction of decision rule based on channel PDP Reason, obtains described second channel time domain response h_opt(n):

In formula, h_optN () is second channel time domain response, P_LSN () is the time-domain power delay profile of LS channel estimation in frequency domain, ρ For power spectrum threshold value, the value size of power spectrum threshold value ρ is decided by the mean power of local frequency-domain pilot sequence, i.e.Wherein, E [| P (k) |²] represent the mean power of local frequency-domain pilot sequence,Represent the noise of scene Power.

Finally, to second channel time domain response h_optN () carries out DFT transform, thus obtain second channel frequency domain response H₂ (k)。

Interference Detection submodule 632 is used for described first channel frequency domain response is carried out Interference Detection based on soft-threshold, Generate described subchannel interference position mark.It uses different threshold values to do under high s/n ratio and low signal-to-noise ratio environment Disturb suppression, such that it is able to improve the AF panel performance in the case of low signal-to-noise ratio.Interference Detection submodule 632 chooses particular door Limit value V, sets detection statistic U the first channel frequency domain response H to obtaining after LS channel estimation in frequency domain₁K () is examined Survey and judgement, thus obtain the subchannel interference position mark of the frequency domain physical layer of single-frequency, arrowband interference:

Wherein, the calculation expression of detection statistic is:

$U\left(k\right)=\frac{\left|H_1\left(k\right)\right|}{\frac{1}{N}\underset{n=0}{\overset{N-1}{\Σ}}\left|H_1\left(n\right)\right|},0\≤k\≤N-1.---\left(6\right)$

AF panel module 640, for identifying according to described subchannel interference position described second channel frequency domain response Carry out mask AF panel, generation the 3rd channel frequency domain response:

The subchannel interference position obtained is identified the sc_index bar as quick AF panel by AF panel module 640 Part, acquisition the 3rd channel frequency domain response after suppression interference:

$H_c\left(k\right)=\left\{\begin{array}{cc}{H}_2\left(k\right),& sc\_index\left(k\right)=1\\ 0,& sc\_index\left(k\right)=0\end{array}\right.,0\≤k\≤N-1.---\left(7\right)$

Channel equalization module 650, for carrying out frequency domain channel equalization to described 3rd channel frequency domain response.

The present embodiment uses frequency domain equalization, to avoid the matrix operations of complexity, based on existing efficient IP kernel algoritic module, has Effect ground reduces the implementation complexity of channel equalization.Frequency domain channel equalization algorithm based on MMSE criterion can be expressed as:

$Y_o\left(k\right)=\frac{Y_i\left(k\right)\·H_c^{*}\left(k\right)}{|H_c\left(k\right){|}^2+\frac{1}{{\mathrm{SNR}}_{est}}},0\≤k\≤N-1.---\left(8\right)$

Additionally, for the innovative part highlighting the present invention, not by proposed by the invention with solution in the present embodiment The unit introducing that technical problem relation is the closest, but this is not intended that in the present embodiment the unit that there is not other.

It is seen that, the present embodiment is system embodiment corresponding to those in the first embodiment, and the present embodiment can be real with first Execute example to work in coordination enforcement.The relevant technical details mentioned in first embodiment is the most effective, in order to reduce Repeat, repeat no more here.Correspondingly, the relevant technical details mentioned in the present embodiment is also applicable in first embodiment.

In sum, the disturbance restraining method of a kind of wireless signal of the present invention and system, it is applied to the wireless expansion of SC-FDMA Frequently communication system.The present invention has combined closely channel estimation in frequency domain technology and frequency domain channel equalization communication technology, i.e. to channel from Scattered time domain response adds time domain noise reduction based on PDP decision rule and processes and the step of Interference Detection based on soft-threshold.Phase Than traditional based on maximum delay L_maxTime domain suppression Noise Method, based on PDP judgement time domain noise reduction process can be further Reduce the noise impact on system；Being simultaneous for specific single-frequency, the environment of arrowband electromagnetic interference, strong jamming based on soft threshold values is examined Survey processes can be with Auto-Sensing certain interference frequency range, and the soft threshold values detection grounds of judgment of improvement estimates that signal to noise ratio chooses door Limit, suppresses the power spectrum component of interference effectively, eliminates the interference impact on system.So, the present invention effectively overcomes existing The various shortcoming in technology is had to have high industrial utilization.

The principle of above-described embodiment only illustrative present invention and effect thereof, not for limiting the present invention.Any ripe Above-described embodiment all can be modified under the spirit and the scope of the present invention or change by the personage knowing this technology.Cause This, have usually intellectual such as complete with institute under technological thought without departing from disclosed spirit in art All equivalences become are modified or change, and must be contained by the claim of the present invention.

Claims (13)

1. a disturbance restraining method for wireless signal, is applied to SC-FDMA spread spectrum radio communications system, it is characterised in that institute The disturbance restraining method stating wireless signal includes:

Generate local frequency-domain pilot sequence；

According to the described local frequency-domain pilot sequence channel dispersion time domain response pair to described SC-FDMA spread spectrum radio communications system The frequency domain response answered carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；

The time domain noise reduction that described first channel frequency domain response carries out decision rule based on channel PDP processes, it is thus achieved that the second letter Road frequency domain response；And described first channel frequency domain response is carried out Interference Detection based on soft-threshold, it is thus achieved that subchannel interference position Put mark；

Described second channel frequency domain response is carried out mask AF panel according to described subchannel interference position mark, obtains the 3rd Channel frequency domain response；

Described 3rd channel frequency domain response is carried out frequency domain channel equalization.

The disturbance restraining method of wireless signal the most according to claim 1, it is characterised in that: described local pilot tone sequence Row are by being spread by Orthogonal Variable Spreading Factor OVSF by frequency pilot sign, and carry out scrambling by GOLD sequence and generate.

The disturbance restraining method of wireless signal the most according to claim 2, it is characterised in that: described orthogonal variable spread spectrum because of Son uses the Walsh sequence of a length of 1024.

The disturbance restraining method of wireless signal the most according to claim 1, it is characterised in that: described second channel frequency domain rings Should be first described first channel frequency domain response to be converted through IDFT, be converted to the first channel time domain response of time domain；Again based on The decision rule of channel PDP carries out time domain noise reduction and processes acquisition second channel time domain response, eventually passes through DFT transform to frequency domain Generate；Wherein, decision rule based on channel PDP is

In formula, h_optRepresent described second channel time domain response；Represent described first channel time domain response；P_LSRepresent LS frequency domain Along spectrum during the time-domain power that channel is estimated, ρ represents power spectrum threshold value.

The disturbance restraining method of wireless signal the most according to claim 4, it is characterised in that: described power spectrum threshold value ρ Mean power and noise power by described local frequency-domain pilot sequence determine.

The disturbance restraining method of wireless signal the most according to claim 4, it is characterised in that: described subchannel interference position Mark is to calculate detection statistic, and according to estimating signal noise ratio level, chooses the detection threshold of correspondence；By described detection statistic Compare with described detection threshold and generate；Wherein, described subchannel interference position is designated0≤k≤N-1；U represents described detection statistic, and0 ≤ k≤N-1, H₁Represent described first channel frequency domain response；V represents described detection threshold.

The disturbance restraining method of wireless signal the most according to claim 6, it is characterised in that: described 3rd channel frequency rings Described second channel frequency domain response should be carried out mask AF panel according to described subchannel interference position mark and obtain:0≤k≤N-1；Wherein, H_cRepresent described 3rd channel frequency domain response；H₂Represent Described second channel frequency domain response.

The disturbance restraining method of wireless signal the most according to claim 1, it is characterised in that: described to described 3rd channel It is to use frequency domain channel equalization algorithm based on MMSE criterion to realize that frequency domain response carries out the step of frequency domain channel equalization.

9. an Interference Suppression System for wireless signal, is applied to SC-FDMA spread spectrum radio communications system, it is characterised in that: institute The suppression system stating wireless signal includes:

Pilot frequency sequence generation module, is used for generating local frequency-domain pilot sequence；

Channel estimation module, is used for according to described local frequency-domain pilot sequence described SC-FDMA spread spectrum radio communications system Frequency response function corresponding to shock response carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；

Time domain noise reduction and interference detection module, for carrying out time domain noise reduction process and interference inspection to described first channel frequency domain response Survey, and obtain second channel frequency domain response and subchannel interference position mark；

AF panel module, for carrying out mask to described second channel frequency domain response according to described subchannel interference position mark AF panel, obtains the 3rd channel frequency domain response；

Channel equalization module, for carrying out frequency domain channel equalization to described 3rd channel frequency domain response.

The Interference Suppression System of wireless signal the most according to claim 9, it is characterised in that: described time domain noise reduction is with dry Disturb detection module to include:

Time domain noise reduction submodule for carrying out the time domain fall of decision rule based on channel PDP to described first channel frequency domain response Make an uproar process, obtain described second channel frequency domain response；

Interference Detection submodule, for described first channel frequency domain response carries out Interference Detection based on soft-threshold, generates institute State subchannel interference position mark.

The Interference Suppression System of 11. wireless signals according to claim 10, it is characterised in that: based on channel PDP sentence Certainly criterion is

In formula, h_optRepresent second channel time domain response；Represent the first channel time domain that described first channel frequency domain response is corresponding Response；P_LSAlong composing when representing the time-domain power of LS channel estimation in frequency domain, ρ represents power spectrum threshold value；And described power spectrum thresholding Value ρ is determined by mean power and the noise power of described local frequency-domain pilot sequence.

The Interference Suppression System of 12. wireless signals according to claim 10, it is characterised in that: described Interference Detection submodule Block is by calculating detection statistic, and described detection statistic is compared with detection threshold and generate described subchannel and do Disturbing station location marker, wherein, described subchannel interference position is designated0≤k≤ N-1；In formula, U represents described detection statistic, and0≤k≤N-1, in formula, H₁Represent described One channel frequency domain response；V_d-highRepresent described detection threshold.

The Interference Suppression System of 13. wireless signals according to claim 9, it is characterised in that: described channel equalization module Use frequency domain channel equalization algorithm based on MMSE criterion that described 3rd channel frequency domain response is carried out frequency domain channel equalization.