CN105827274B - The disturbance restraining method and system of a kind of wireless signal - Google Patents
The disturbance restraining method and system of a kind of wireless signal Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7107—Subtractive interference cancellation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/71—Interference-related aspects the interference being narrowband interference
- H04B1/7102—Interference-related aspects the interference being narrowband interference with transform to frequency domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7105—Joint detection techniques, e.g. linear detectors
- H04B1/71055—Joint detection techniques, e.g. linear detectors using minimum mean squared error [MMSE] detector
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- H04L25/022—Channel estimation of frequency response
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
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Abstract
The present invention provides a kind of disturbance restraining method and system of wireless signal, applied to SC FDMA spread spectrum radio communications systems, including：The local frequency-domain pilot sequence of generation；LS channel estimation in frequency domain is carried out to the corresponding frequency domain response of the channel dispersion time domain response of SC FDMA spread spectrum radio communications systems according to local frequency-domain pilot sequence, obtains the first channel frequency domain response；The time domain noise reduction processing of the decision rule based on channel PDP is carried out to the first channel frequency domain response, obtains second channel frequency domain response；And the Interference Detection based on soft-threshold is carried out to the first channel frequency domain response, obtain subchannel interference position mark；Mask AF panel is carried out according to subchannel interference position mark to second channel frequency domain response, obtains third channel frequency domain response；Frequency domain channel equalization is carried out to third channel frequency domain response.The present invention reduces influence of the noise to communication system, effectively inhibit the power spectrum component of interference, eliminate influence of the interference to communication system.
Description
Technical field
The present invention relates to a kind of communication technology, more particularly 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 are quickly grown, aviation radio spread spectrum communication electromagnetic interference environment
More complicated, the requirement in terms of anti-interference index is also higher and higher, and still there is the research of this respect in related communication field very much
Value.
Traditional channel estimation and equalization technology can compensate influence of the Complex Channel to system to a certain extent.Mesh
Before, include using more channel estimation and equalization technology：Channel estimation in frequency domain algorithm based on pilot frequency sequence and based on transformation
The channel estimation method in domain.Wherein, the channel estimation in frequency domain algorithm based on pilot frequency sequence includes least square (Least
Square, LS) channel estimation method, least mean-square error (Minimum Mean Square Error, MMSE) channel estimate
The channel of calculating method and 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 interference of the Complex Channel to signal to a certain extent, pass
The single-carrier frequency-domain estimation of system and balancing technique interfered in single-frequency, narrowband etc. performance under complicated electromagnetic interference environment compared with
Difference.Also, special space flight spread spectrum radio communications system occupancy frequency range is wider, and radio environment often has complicated electronic countermeasure
Interference, such as high-power single-frequency or narrowband are interfered, simple only by traditional channel estimation and equalization technology
Fight complicated electromagnetic interference.
Invention content
In view of the foregoing deficiencies of prior art, the purpose of the present invention is to provide a kind of AF panels of wireless signal
Method and system, for solving channel estimation and equalization skill traditional in SC-FDMA spread spectrum radio communications systems in the prior art
Art can not effectively solve the problems, such as influence of the complicated electromagnetic interference to system.
In order to achieve the above objects and other related objects, the present invention provides a kind of disturbance restraining method of wireless signal, should
For SC-FDMA spread spectrum radio communications systems, the disturbance restraining method of the wireless signal includes：The local pilot tone sequence of generation
Row；According to channel dispersion time domain response pair of the local frequency-domain pilot sequence to the SC-FDMA spread spectrum radio communications systems
The frequency domain response answered carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；To first channel frequency domain response into
The time domain noise reduction processing of decision rule of the row based on channel PDP, obtains second channel frequency domain response；And to first channel frequency
Domain response carries out the Interference Detection based on soft-threshold, obtains subchannel interference position mark；To the second channel frequency domain response
It is identified according to the subchannel interference position and carries out mask AF panel, obtain third channel frequency domain response；The third is believed
Road frequency domain response carries out frequency domain channel equalization.
In one embodiment of the invention, the local frequency-domain pilot sequence is by the way that frequency pilot sign is expanded by orthogonal variable
The frequency factor is spread, and is scrambled by GOLD sequences to generate.
In one embodiment of the invention, the Orthogonal Variable Spreading Factor OVSF use length for 1024 Walsh sequences.
In one embodiment of the invention, the second channel frequency domain response is first to pass through first channel frequency domain response
IDFT transformation is crossed, is converted to the first channel time domain response of time domain；The 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 is generated to frequency domain；Wherein, the judgement based on channel PDP is accurate
It is thenIn formula, hoptRepresent the second channel time domain response；Represent described first
Channel time domain responds；PLSIt represents to represent power spectrum threshold value along spectrum, ρ during the time-domain power of LS channel estimation in frequency domain.
In one embodiment of the invention, the power spectrum threshold value ρ by the local frequency-domain pilot sequence average work(
Rate and noise power determine.
In one embodiment of the invention, subchannel interference position mark is to calculate detection statistic, and according to estimating
Signal noise ratio level is counted, chooses corresponding detection threshold；The detection statistic with the detection threshold is compared and is generated
's；Wherein, the subchannel interference position is identified as0≤k≤N-1；Described in U is represented
Detection statistic, and0≤k≤N-1, H1Represent first channel frequency domain response；Described in V is represented
Detection threshold.
In one embodiment of the invention, the third channel frequency domain response is by the second channel frequency domain response foundation
The subchannel interference position mark carries out mask AF panel and obtains：0
≤k≤N-1；Wherein, HcRepresent the third channel frequency domain response；H2Represent the second channel frequency domain response.
In one embodiment of the invention, described the step of frequency domain channel equalization is carried out to the third channel frequency domain response
It is to use to realize based on the frequency domain channel equalization algorithm of MMSE criterion.
The invention also discloses a kind of Interference Suppression System of wireless signal, applied to SC-FDMA radio spread spectrum communications system
System, the suppression system of the wireless signal include：Pilot frequency sequence generation module, for generating local frequency-domain pilot sequence；Channel
Estimation module, for according to shock response of the local frequency-domain pilot sequence to the SC-FDMA spread spectrum radio communications systems
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 carrying out time domain noise reduction processing and Interference Detection to first channel frequency domain response, and obtain second channel frequency domain response and
Subchannel interference position identifies；AF panel module, for being interfered according to the subchannel the second channel frequency domain response
Station location marker carries out mask AF panel, obtains third channel frequency domain response；Channel equalization module, for the third channel
Frequency domain response carries out frequency domain channel equalization.
In one embodiment of the invention, the time domain noise reduction and interference detection module include：Time domain noise reduction submodule is used
It is handled in the time domain noise reduction that the decision rule based on channel PDP is carried out to first channel frequency domain response, obtains described second
Channel frequency domain response；Interference Detection submodule, for carrying out the interference inspection based on soft-threshold to first channel frequency domain response
It surveys, generates the subchannel interference position mark.
In one embodiment of the invention, the decision rule based on channel PDP is
In formula, hoptRepresent second channel time domain response；Represent that corresponding first channel time domain of first channel frequency domain response is rung
It should；PLSIt represents to represent power spectrum threshold value along spectrum, ρ during the time-domain power of LS channel estimation in frequency domain；And the power spectrum threshold value ρ
It is determined by the mean power and noise power of the local frequency-domain pilot sequence.
In one embodiment of the invention, the Interference Detection submodule be by calculating detection statistic, and will described in
Detection statistic is compared with detection threshold and generates the subchannel interference position mark, wherein, the subchannel is done
Disturbing station location marker is0≤k≤N-1；In formula, U represents the detection statistic, and0≤k≤N-1, in formula, H1Represent first channel frequency domain response；Vd-highRepresent the detection
Thresholding.
In one embodiment of the invention, the channel equalization module is calculated using the frequency domain channel equalization based on MMSE criterion
Method carries out frequency domain channel equalization to the third channel frequency domain response.
As described above, the disturbance restraining method and system of a kind of wireless signal of the present invention, wirelessly expand applied to SC-FDMA
Frequency communication system.The present invention has combined closely channel estimation in frequency domain technology and the frequency domain channel equalization communication technology, i.e., to channel from
Scattered time domain response increases the step of time domain noise reduction processing based on PDP decision rules and Interference Detection based on soft-threshold.Phase
Than traditional based on maximum delay LmaxTime domain inhibit Noise Method, based on PDP judgement time domain noise reduction processing can be further
Reduce influence of the noise to system；Simultaneously for the environment of specific single-frequency, narrowband electromagnetic interference, the strong jamming inspection based on soft threshold values
Survey processing can choose door with Auto-Sensing certain interference frequency range, improved soft threshold values detection grounds of judgment estimation signal-to-noise ratio
Limit effectively inhibits the power spectrum component of interference, eliminates influence of the interference to system.
Description of the drawings
Fig. 1 is shown as a kind of flow diagram of the disturbance restraining method of wireless signal disclosed by the embodiments of the present invention.
Fig. 2 is shown as the local pilot tone in a kind of disturbance restraining method of wireless signal disclosed by the embodiments of the present invention
The generation of sequence and multiplexing structure schematic diagram.
Fig. 3 is shown as the antijam communication in a kind of disturbance restraining method of wireless signal disclosed by the embodiments of the present invention
Module diagram.
Fig. 4 be shown as a kind of disturbance restraining method of wireless signal disclosed by the embodiments of the present invention based on channel PDP's
The performance curve schematic diagram of the time domain noise reduction of decision rule.
Fig. 5 is shown as a kind of jamproof property of single-frequency of the disturbance restraining method of wireless signal disclosed by the embodiments of the present invention
It can curve synoptic diagram.
Fig. 6 is shown as a kind of base structure diagram of the Interference Suppression System of wireless signal disclosed by the embodiments of the present invention.
Component label instructions
S10~S50 steps
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 modules
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, 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 pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also be based on different viewpoints with application, without departing from
Various modifications or alterations are carried out under the spirit of the present invention.It should be noted that in the absence of conflict, following embodiment and implementation
Feature in example can be combined with each other.
Please refer to attached drawing.It should be noted that the diagram provided in following embodiment only illustrates this hair in a schematic way
Bright basic conception, component count when only display is with related component in the present invention rather than according to actual implementation in schema then,
Shape and size are drawn, and kenel, quantity and the ratio of each component can be a kind of random change during actual implementation, and its component
Being laid out kenel may also be increasingly complex.
The present invention a kind of wireless signal disturbance restraining method and system be combine closely channel estimation in frequency domain with
Under the basis for the communication technology that weighs, a kind of of proposition has compared with the channel estimation of strong anti-interference ability and the system of channel equalization.This
Invention inhibits noise skill using the time domain of the decision rule based on channel PDP (Power Delay Profile, power-delay spectrum)
Art inhibits class white noise acoustic jamming, such as AWGN, sea clutter noise jamming；Using the interference detection technique based on soft threshold values, cooperation
Mask AF panel further suppresses the interference of single-frequency and narrowband.
Embodiment 1
Present embodiment discloses a kind of AF panel sides of the wireless signal applied to SC-FDMA spread spectrum radio communications systems
Method for inhibiting noise, and solves the interference of feature single-frequency or narrowband to system.
As 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 generation mentality of designing, it is specific as shown in Figure 2.Frequency pilot sign p passes through OVSF (Orthogonal
Variable Spreading Factor, Orthogonal Variable Spreading Factor OVSF) spread spectrum after be multiplexed into data-signal.Using CDMA
Pilot tone generation mentality of designing, the local frequency-domain pilot sequence of generation will not temporary independence time interval resource, simplify frame structure.
As shown in Fig. 2, frequency pilot sign p is spread by the Walsh sequences that length is 1024, carried out by Gold sequence
Scrambling obtains.Wherein, it is 1024 for scrambled Gold sequence length, and using LTE (Long Term Evolution, length
Phase evolution) generator polynomial generation in agreement.The composite symbol after Gold sequence scrambles, pass through after adding in single carrier
DFT-S-OFDM (Discrete Fourier Transform-Spread OFDM, the orthogonal frequency of discrete Fourier transform spread spectrum
Divide multiplexing multiple access technique) technology realization single carrier communication, after being inserted into cyclic prefix CP (Cyclic Prefix), feeding is penetrated
Frequency front end.
In the present embodiment, frequency pilot sign p=(1+i)/2, after length is the Walsh sequence spread spectrums of M, using length
After spending the Gold sequence scrambling for M, local frequency-domain pilot sequence is obtained multiplied by power factor b.
Step S20, according to the local frequency-domain pilot sequence to the channels of the SC-FDMA spread spectrum radio communications systems from
It dissipates the corresponding frequency domain response of time domain response and carries out LS channel estimation in frequency domain, obtain the first channel frequency domain response.
After the local frequency-domain pilot sequence of generation, at a wireless receiver using LS channel estimation in frequency domain to the frequency domain of high intensity
It interferes into line trace, analysis and inhibition.It is analyzed by the result of LS channel estimation in frequency domain, detection single-frequency, narrowband interference exist
The distribution situation of frequency domain channel；LS frequency domain estimated results are transformed into time domain simultaneously, it is corresponding to choose channel maximum path time delay
Tap inhibits windowing thresholding as time domain white noise.With reference to channel estimation and equalization technology, the present embodiment it is specific anti-interference
Structure it is as shown in Figure 3.
The digital front-end output data of wireless receiver is accorded with by the single carrier after synchronization unit and removal cyclic prefix CP
NumberWherein M is the sampling point number of a discrete single-carrier symbol.
As shown in figure 3, the signal y (n) after channel and removal cyclic prefix CP of the present embodiment represents receive one
The discrete single-carrier symbol of a time-domain, wherein,0≤n≤M-1；Wherein, h (n) is letter
Road discrete time-domain response；X (n) is transmitting discrete symbols；W (n) represents discrete and independent white Gaussian noise；Symbolic indication is rolled up
Product operation.Also, channel dispersion time domain responseA in formulalRepresent the gain in path, l expressions are not gone the same way
Diameter time delay, L represent channel maximum path CIR (Channel Impulse Response, channel impulse response).In the present embodiment
In, the discrete single-carrier symbol of a time-domain shares 2048 sampling points, i.e. M=2048.
Also, therefore channel dispersion time domain response, need to be converted to letter by the present embodiment using LS channel estimation in frequency domain
Road discrete frequency domain response, i.e., pass through DFT (Discrete Fourier to the discrete single carrier of a time-domain
Transform, discrete Fourier transform), while subcarrier demapping is carried out to the frequency domain data by DFT transform, then k-th
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 to send discrete symbol
Number frequency domain response, W (k) represent white Gaussian noise frequency domain response, H (k) represent channel dispersion frequency domain response, N represent frequency domain
Frequency domain number of samples after subcarrier demapping.
Channel estimation in frequency domain is carried out by LS criterion, the first channel frequency domain response after obtaining channel according to a preliminary estimate is：
Wherein, Y (k) is local frequency-domain pilot sequence to receive discrete single-carrier symbol frequency domain response, P (k).
Step S30 carries out at the time domain noise reduction of the decision rule based on channel PDP first channel frequency domain response
Reason obtains second channel frequency domain response；And the Interference Detection based on soft-threshold is carried out to first channel frequency domain response, it obtains
Subchannel interference position identifies.
It is not difficult to find out that after LS channel estimation in frequency domain, still there is very big noise jamming from formula (1).Therefore one
As using in the time domain to the first channel frequency domain response carry out noise reduction process.
Therefore, first to the first channel frequency domain response carry out IDFT (InverseDiscreteFourierTransform,
Inverse discrete Fourier transform) transformation, obtain the corresponding first channel time domain response of the first channel frequency domain responseI.e.：
At present, since most CIR energy is concentrated in L tap of first few, so more commonly used is to pass through
Noise power except zeroization channel tap, in this way can a degree of interference for reducing white noise character to the shadow of system
Ring, wherein, have white noise character interference include Gaussian distributed free space noise and Rayleigh distributed with
The sea clutter interference of logarithm normal distribution.It is therefore assumed that maximum channel impulse response tap length is Lmax, then press down by noise
Time domain channel response after system is：
Wherein, Lmax=Lτ+S；LτMaximum multipath time delay under the channel circumstance of expression system, S represent signal transmitted bandwidth,
And time domain noise suppression algorithm usually chooses maximum delay value as CP length.It can be seen that from above-mentioned decision rule more in present channel
Diameter time delay is less than LmaxWhen, it chooses fixed channel delay response threshold and often introduces more noises.Secondly, in multipath
Prolong more badly, i.e., when maximum multipath time delay value is larger, such as severe urban district channel model, due to the letter compared with long time delay diameter
Number Energy distribution proportion often very little, chooses maximum LmaxIt is similary although obtaining more Delays as decision threshold
Inevitably introduce more noises.
In summary problem, the present embodiment propose the time domain noise reduction processing of the improved decision rule based on channel PDP,
Wherein, the decision rule based on channel PDP is expressed as：
In formula, hopt(n) it is second channel time domain response, PLS(n) it 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 hopt(n) DFT transform is carried out, so as to obtain second channel frequency domain response H2(k)。
Further, the mean power of local frequency-domain pilot sequence is：
E[|P(k)|2]=bE [| Yi(k)|2]； (3)
In formula, b is the pilot power factor, due to receiving signal yi(n) power is modulated to unit 1, can be obtained according to above formula
Power to ground frequency-domain pilot sequence is b.Noise power is expressed as：
Further, the present embodiment in order to realize be directed to different signal-to-noise ratio in the environment of AF panel, it is also proposed that it is right
Interference Detection of first channel frequency domain response 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, so as to improve the AF panel performance in low signal-to-noise ratio.Specified threshold V is chosen,
Setting detection statistic U is detected and adjudicates to the first channel frequency domain response obtained after LS channel estimation in frequency domain, from
And obtain single-frequency, the subchannel interference position of the frequency domain physical straton mark that narrowband interferes：
Wherein, the calculation expression of detection statistic is：
In formula, H1(k) the first channel frequency domain response is represented.
In the present embodiment, in the environment of channel is in high s/n ratio, i.e. SNRest>0dB, set detection threshold as
Vd-high, detection statistic U is analyzed, the strong jamming subchannel for being higher than threshold value is distinguish, decision rule is：
Similarly, in the environment of channel is in low signal-to-noise ratio, using low signal-to-noise ratio detection threshold Vd-low, interference is examined
Survey judgement.If sc_index (k) identifies current sub-channel statistic for subchannel interference position and is more than thresholding in formula, label 0,
Otherwise label 1.
Step S40 identifies the second channel frequency domain response according to the subchannel interference position and carries out mask interference
Inhibit, obtain third channel frequency domain response.
Using the subchannel interference position mark sc_index of acquisition as the condition of quick AF panel, obtained after inhibiting interference
Obtain third channel frequency domain response：
Step S50 carries out frequency domain channel equalization to the third channel frequency domain response.
The present invention is using frequency domain equalization, to avoid complicated matrix operation, 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：
Wherein, SNRestIt is the current estimation signal-to-noise ratio for receiving symbol, Yo(k) it is defeated after equilibrium for discrete data symbol
The frequency domain response gone out, Yi(k) it is responded for the input frequency domain of discrete data symbol,For Hc(k) complex conjugate.Also, by public affairs
Formula (3) and formula (4) estimate Signal to Noise Ratio (SNR)estIt can be expressed as：
It should be noted that the step of above method divides, it is intended merely to describe clear, when realization can be merged into one
Step splits certain steps, is decomposed into multiple steps, as long as comprising identical logical relation, all in this patent
In protection domain；To inessential modification is either added in algorithm in flow or introduces inessential design, but do not change
Become the core design of its algorithm and flow all in the protection domain of the patent.
Further, in order to verify the noise suppressed of the disturbance restraining method of the wireless signal of the present embodiment and single-frequency resist it is dry
Immunity energy has built system simulation platform, and simulation result is analyzed using Matlab tools.This emulation is to be directed to
SC-FDMA spread spectrum radio communications systems, respectively in awgn channel model and fading channel model carry out time domain noise reduction performance and
What AF panel performance carried out.Wherein, the relevant configured parameter of SC-FDMA spread spectrum radio communications systems refers to the following table 1；Decline letter
Road model refers to the following table 2 using typical rural model (cost207RAx6) channel model, parameter configuration.
1 system relevant configured parameter of table
The typical rural fading channel parameter of table 2
Also, the SC-FDMA spread spectrum radio communications systems of this emulation also suffer from mono-tone interference.Mono-tone interference is to instigate
With the interference signal of single sine wave or multiple sine waves.This emulation is in the signal bandwidth of 7.68MHz, is followed to each
Ring single-carrier symbol generates the random interference of a frequency point, and on the symbol, the power of interference is preset superposition.This is imitative
Really interference model is：Wherein, I is interference signal, f be with
The frequency values for the interference that machine generates, k are data point serial numbers, fs=15.36MHz represents system sampling frequency；BW=7.68MHz,
Represent signal bandwidth.
The emulation of time domain noise reduction performance is the different signal-to-noise ratio (Signal-to-Noise emulated before and after noise reduction process
Ratio, SNR) LS estimation least mean-square error (Mean Square Error, MSE).Also, in order to verify that the present embodiment carries
The performance of time domain noise reduction processing gone out, the emulation of this time domain noise reduction performance is respectively in awgn channel model and fading channel model
The time domain of the decision rule based on channel PDP of the fixed CIR time delay window noise reductions of tradition and the present embodiment is respectively adopted in lower progress
Noise reduction.The simulation result of this time domain noise reduction performance is as shown in Figure 4.It can be with it has been observed that believing in AWGN by comparison from Fig. 4
In the environment of road model and typical fading channel model, the decision rule based on channel PDP that is proposed using the present embodiment
Time domain noise reduction processing is more excellent to the inhibition of white noise.
The emulation of single-frequency interference free performance is to emulate the numerical value of the bit error rate under different signal interference ratios.Also, in order to
It verifies the performance for the anti-interference process that the present embodiment proposes, simulates the bit error rate by the present embodiment anti-interference process respectively
Curve graph and the errored bit without the present embodiment anti-interference process (Interference Detection and mask AF panel based on soft-threshold)
Rate curve graph, to facilitate comparison.The simulation result of this interference free performance is as shown in Figure 5.From Fig. 5 by comparison can from
It was found that it is 10 in the bit error rate-3When horizontal, after single-frequency anti-interference process (I-Cancellation) through this embodiment, system
Performance has the gain of 8.6dB.
Embodiment 2
Present embodiment discloses a kind of Interference Suppression System of wireless signal, applied to SC-FDMA radio spread spectrum communications system
System.The Interference Suppression System of the wireless signal of the present embodiment is mainly used for inhibiting noise, and solve feature single-frequency or narrowband to being
The interference of system.
As shown in fig. 6, the Interference Suppression System of the wireless signal of the present embodiment includes：
Pilot frequency sequence generation module 610, for generating local frequency-domain pilot sequence.610 reference of pilot frequency sequence generation module
The mentality of designing of the pilot tone generation of CDMA (Code Division Multiple Access, CDMA), specifically such as Fig. 2 institutes
Show.Frequency pilot sign p is expanded by OVSF (Orthogonal Variable Spreading Factor, Orthogonal Variable Spreading Factor OVSF)
It is multiplexed into data-signal after frequency.Mentality of designing is generated using the pilot tone of CDMA, the local frequency-domain pilot sequence of generation will not
The time interval resource of temporary independence, simplifies frame structure.
Channel estimation module 620, for according to the local frequency-domain pilot sequence to the SC-FDMA radio spread spectrum communications
The corresponding frequency response function of shock response of system carries out LS channel estimation in frequency domain, generates the first channel frequency domain response：
DFT transform is carried out to the discrete single-carrier symbol of a time-domain of reception, so as to obtain channel dispersion frequency domain
Respond H (k)；Again by carrying out channel estimation in frequency domain by LS criterion, the first channel frequency after obtaining channel according to a preliminary estimate is rung
It should be：
Wherein, Y (k) is local frequency-domain pilot sequence to receive discrete single-carrier symbol frequency domain response, P (k).
Time domain noise reduction and interference detection module 630, for carrying out time domain noise reduction processing to 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 used to carry out the decision rule based on channel PDP to first channel frequency domain response
Time domain noise reduction processing, obtain the second channel frequency domain response：
First, IDFT transformation is carried out to the first channel frequency domain response, obtains the first channel frequency domain response H1(k) corresponding
One channel time domain responds
Secondly, then to the first channel time domain respondAt the time domain noise reduction for carrying out the decision rule based on channel PDP
Reason, obtains the second channel time domain response hopt(n)：
In formula, hopt(n) it is second channel time domain response, PLS(n) it 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 hopt(n) DFT transform is carried out, so as to obtain second channel frequency domain response H2
(k)。
Interference Detection submodule 632 is used to carry out the Interference Detection based on soft-threshold to first channel frequency domain response,
Generate the subchannel interference position mark.It is done under high s/n ratio and low signal-to-noise ratio environment using different threshold values
Inhibition is disturbed, so as to improve the AF panel performance in low signal-to-noise ratio.Interference Detection submodule 632 chooses particular door
Limit value V, setting detection statistic U is to the first channel frequency domain response H for being obtained after LS channel estimation in frequency domain1(k) it is examined
It surveys and adjudicates, so as to obtain the subchannel interference position mark of the frequency domain physical layer of single-frequency, narrowband interference：
Wherein, the calculation expression of detection statistic is：
AF panel module 640, for being identified to the second channel frequency domain response according to the subchannel interference position
Mask AF panel is carried out, generates third channel frequency domain response：
AF panel module 640 is using the subchannel interference position mark sc_index of acquisition as the item of quick AF panel
Part obtains third channel frequency domain response after inhibiting interference：
Channel equalization module 650, for carrying out frequency domain channel equalization to the third channel frequency domain response.
The present embodiment uses frequency domain equalization, to avoid complicated matrix operation, 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：
In addition, in order to protrude the innovative part of the present invention, it will not be proposed by the invention with solution in the present embodiment
The less close unit of technical problem relationship introduces, but this does not indicate that there is no other units in the present embodiment.
It is not difficult to find that the present embodiment is system embodiment corresponding to those in the first embodiment, the present embodiment can be with first in fact
Example is applied to work in coordination implementation.The relevant technical details mentioned in first embodiment are still effective in the present embodiment, in order to reduce
It repeats, which is not described herein again.Correspondingly, the relevant technical details mentioned in the present embodiment are also applicable in first embodiment.
In conclusion the disturbance restraining method and system of a kind of wireless signal of the present invention, wirelessly expand applied to SC-FDMA
Frequency communication system.The present invention has combined closely channel estimation in frequency domain technology and the frequency domain channel equalization communication technology, i.e., to channel from
Scattered time domain response increases the step of time domain noise reduction processing based on PDP decision rules and Interference Detection based on soft-threshold.Phase
Than traditional based on maximum delay LmaxTime domain inhibit Noise Method, based on PDP judgement time domain noise reduction processing can be further
Reduce influence of the noise to system；Simultaneously for the environment of specific single-frequency, narrowband electromagnetic interference, the strong jamming inspection based on soft threshold values
Survey processing can choose door with Auto-Sensing certain interference frequency range, improved soft threshold values detection grounds of judgment estimation signal-to-noise ratio
Limit effectively inhibits the power spectrum component of interference, eliminates influence of the interference to system.So the present invention effectively overcomes now
There is the various shortcoming in technology and have high industrial utilization.
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology all can carry out modifications and changes under the spirit and scope without prejudice to the present invention to above-described embodiment.Cause
This, those of ordinary skill in the art is complete without departing from disclosed spirit and institute under technological thought such as
Into all equivalent modifications or change, should by the present invention claim be covered.
Claims (7)
- A kind of 1. disturbance restraining method of wireless signal, applied to SC-FDMA spread spectrum radio communications systems, which is characterized in that institute The disturbance restraining method for stating wireless signal includes：The local frequency-domain pilot sequence of generation；According to channel dispersion time domain response pair of the local frequency-domain pilot sequence to the SC-FDMA spread spectrum radio communications systems The frequency domain response answered carries out LS channel estimation in frequency domain, obtains the first channel frequency domain response；Carry out composing the time domain noise reduction processing of the decision rule of delay PDP to first channel frequency domain response based on channel power, Obtain second channel frequency domain response；And the Interference Detection based on soft-threshold is carried out to first channel frequency domain response, obtain son Channel disturbance station location marker；Wherein, the second channel frequency domain response is that first channel frequency domain response first is passed through IDFT Transformation is converted to the first channel time domain response of time domain；The decision rule for composing delay PDP based on channel power again carries out time domain drop Processing of making an uproar obtains second channel time domain response, eventually passes through DFT transform and is generated to frequency domain；Wherein, it is composed based on channel power Delay PDP decision rule beIn formula, hoptRepresent the second channel time domain response；Represent described first Channel time domain responds；PLSIt represents to represent power spectrum threshold value along spectrum, ρ during the time-domain power of LS channel estimation in frequency domain；The second channel frequency domain response according to the subchannel interference position is identified and carries out mask AF panel, obtains third Channel frequency domain response；Wherein, the subchannel interference position mark is to calculate detection statistic, and according to estimation signal-to-noise ratio water It is flat, choose corresponding detection threshold；The detection statistic and the detection threshold are compared and generated；Wherein, institute Subchannel interference position is stated to be identified asU represents the detection statistics Amount, andH1Represent first channel frequency domain response；V represents the detection Thresholding；N represents frequency domain number of samples；The third channel frequency domain response is：Wherein, HcRepresent the third channel frequency domain response；H2Represent the second channel frequency domain response；Frequency domain channel equalization is carried out to the third channel frequency domain response.
- 2. the disturbance restraining method of wireless signal according to claim 1, it is characterised in that：The local pilot tone sequence Row are by the way that frequency pilot sign is spread by Orthogonal Variable Spreading Factor OVSF, and are scrambled by GOLD sequences to generate.
- 3. the disturbance restraining method of wireless signal according to claim 2, it is characterised in that：Orthogonal variable spread spectrum because Son use length for 1024 Walsh sequences.
- 4. the disturbance restraining method of wireless signal according to claim 1, it is characterised in that：The power spectrum threshold value ρ It is determined by the mean power and noise power of the local frequency-domain pilot sequence.
- 5. the disturbance restraining method of wireless signal according to claim 1, it is characterised in that：It is described to the third channel The step of frequency domain response progress frequency domain channel equalization is to use to realize based on the frequency domain channel equalization algorithm of MMSE criterion.
- 6. a kind of Interference Suppression System of wireless signal, applied to SC-FDMA spread spectrum radio communications systems, it is characterised in that：Institute The suppression system for stating wireless signal includes：Pilot frequency sequence generation module, for generating local frequency-domain pilot sequence；Channel estimation module, for according to the local frequency-domain pilot sequence to the SC-FDMA spread spectrum radio communications systems The corresponding frequency response function of 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 processing and interference inspection to first channel frequency domain response It surveys, and obtains second channel frequency domain response and subchannel interference position mark；AF panel module carries out mask for being identified to the second channel frequency domain response according to the subchannel interference position AF panel obtains third channel frequency domain response；Channel equalization module, for carrying out frequency domain channel equalization to the third channel frequency domain response；The time domain noise reduction and interference detection module include：The judgement that time domain noise reduction submodule is used to carry out composing delay PDP to first channel frequency domain response based on channel power is accurate Time domain noise reduction processing then, obtains the second channel frequency domain response；Interference Detection submodule for carrying out the Interference Detection based on soft-threshold to first channel frequency domain response, generates institute State subchannel interference position mark；Based on channel power compose delay PDP decision rule beIn formula, hoptRepresent second channel time domain response；Represent corresponding first channel time domain of first channel frequency domain response Response；PLSIt represents to represent power spectrum threshold value along spectrum, ρ during the time-domain power of LS channel estimation in frequency domain；And the power spectrum thresholding Value ρ is determined by the mean power and noise power of the local frequency-domain pilot sequence；The Interference Detection submodule is to pass through meter Detection statistic is calculated, and the detection statistic and detection threshold are compared and generates the subchannel interference position and identifies , wherein, the subchannel interference position is identified asFormula In, U represents the detection statistic, andIn formula, H1Represent first letter Road frequency domain response；Vd-highRepresent the detection threshold, N represents frequency domain number of samples.
- 7. the Interference Suppression System of wireless signal according to claim 6, it is characterised in that：The channel equalization module is adopted Frequency domain channel equalization is carried out to the third channel frequency domain response with based on the frequency domain channel equalization algorithm of MMSE criterion.
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