CN108233987A - Eliminate the system and method for ultra-broadband signal intersymbol interference under multipath noise channel - Google Patents
Eliminate the system and method for ultra-broadband signal intersymbol interference under multipath noise channel Download PDFInfo
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- CN108233987A CN108233987A CN201810020981.4A CN201810020981A CN108233987A CN 108233987 A CN108233987 A CN 108233987A CN 201810020981 A CN201810020981 A CN 201810020981A CN 108233987 A CN108233987 A CN 108233987A
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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
- H04B1/7163—Spread spectrum techniques using impulse radio
- H04B1/719—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
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- 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
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
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Abstract
The present invention relates to a kind of system and methods for eliminating ultra-broadband signal intersymbol interference under multipath noise channel.By setting suitable threshold value, searcher receiver ultra-wide band signal pulses are to detect successfully until signal level is more than threshold value；Then, it is extracted using signal window and receives signal, and the composite signal pulse that will be detected（It is mixed by signal pulse and more than one multipath interference signal）It is placed on the centre of signal window；Receiving signal before demodulation will be handled by intersymbol interference ISI arresters, to remove intersymbol interference.The present invention without obtaining channel information or channel estimation in advance, without analog-to-digital conversion；Desired signal pulse can be distinguished and be accurately positioned by this method with disturbing pulse；Signal does not use traditional reception pulse when demodulating, but uses the signal peaks generated after wavelet transformation and high-pass filtering.
Description
Technical field
The invention belongs to super broad band radio communication fields, are mainly used in ultra-wideband impulse radio signal in multipath noise
The elimination of intersymbol interference under channel, and in particular to ultra-broadband signal intersymbol interference is under a kind of elimination multipath noise channel
System and method.
Background technology
Ultra wide band (ultra wideband, abbreviation UWB) technology is a kind of extremely promising inexpensive short distance ultrahigh speed
Wireless communication technique.Impulse radio is one of its wherein main realization method.Impulse radio uses short time pulse, from
And a signal is generated, signal has ultra-wide (several GHz) bandwidth.Therefore, UWB wireless channels are high-frequency selectivity.
Receiving has a large amount of analysable multi-path components in signal.Delay more than 30 seconds is fairly common.UWB technology is applied to nothing
Line personal area network (WPANS), data rate is more than 110Mbps, even if not encoding or extending, corresponding symbol period
Again smaller than 10 nanoseconds.Therefore, the intersymbol interference (intersymbol interference, abbreviation ISI) of super-broadband tech is no
It can avoid, and it is then that ultra wide band reliable communication is essential that ISI interference, which is eliminated,.
The conventional method for tackling ISI is using digital equalizer.However, ultra-wideband impulse radio signal bandwidth ultra-wide,
Analog-to-digital conversion needs the sampling rate of superelevation, realizes that difficult and cost is high；Secondly as the ultralow duty ratio of UWB pulses and pole
Short pulse width needs fairly large number of balanced device node and balancing speed superelevation at the high velocities.These are all caused
The serious hindrance that ultra-wideband impulse radio intersymbol interference ISI is eliminated.
Invention content
The purpose of the present invention is to provide a kind of systems for eliminating ultra-broadband signal intersymbol interference under multipath noise channel
And method, the present invention without obtaining channel information or channel estimation in advance, without analog-to-digital conversion；Desired signal pulse is with doing
Disturbing pulse can be distinguished and be accurately positioned by the method for the present invention；Signal does not use traditional reception pulse when demodulating, and
It is using the signal peaks generated after wavelet transformation and high-pass filtering.
To achieve the above object, the technical scheme is that：Ultra-broadband signal accords under a kind of elimination multipath noise channel
The system interfered between number, including
Signal search module for searching for the ultra-wide band signal pulses higher than predetermined threshold value, and determines its time-domain position；
Signal window module completely intercepts the ultra-broadband signal arteries and veins of the signal search block search using signal window
Punching, the signal window size are emit signal width twice；
ISI arresters, for eliminating ultra-wide band signal pulses intersymbol interference, i.e., to the signal window module intercepts
Ultra-wide band signal pulses carry out wavelet transformation, then, high-pass filtering are carried out to the ultra-wide band signal pulses after wavelet transformation, to obtain
Take signal containing spike, then and, k-th of maximum value of the signal of the spike is searched for, and determine its time-domain position, at the beginning of k
Beginning takes 1, then, extracts the signal peaks of the signal containing spike by signal window in the time-domain position, is sent to
Receiver module；
Receiver module and judging module receive the signal peaks for the signal containing spike for sending ISI arresters, and
The signal peaks are related to template signal progress, if correlation is more than predetermined threshold value, which is required
Signal peaks, and make decisions, the signal peaks are otherwise abandoned, and judge whether k is less than preset N, if being less than, k+
1, and signal peaks are extracted again through ISI arresters, until the correlation of number spike of extraction and template signal is more than in advance
Determining threshold value, then makes decisions.
In an embodiment of the present invention, wavelet transformation is carried out to the ultra-wide band signal pulses of the signal window module intercepts
Concrete mode it is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, what is be disturbed is super
Wideband signal pulses can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 },
ciRepresent the amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
In an embodiment of the present invention, the signal containing spike includes two signal peaks and two interference spikes.
In an embodiment of the present invention, the Amplitude Ration of the signal peaks and interference spike is equal to signal pulse and interference arteries and veins
The Amplitude Ration of punching, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
In an embodiment of the present invention, the signal peaks and interference spike between time delay be equal to signal pulse with
Delay time between disturbing pulse.
In an embodiment of the present invention, it is described in the time-domain position by signal window by the signal of the signal containing spike
The signal window size that spike extracts middle use should be not less than the width of signal peaks.
The present invention also provides a kind of method for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, including such as
Lower step,
Step 1：Search is higher than the ultra-wide band signal pulses of predetermined threshold value, and determines its time-domain position.
Step 2：Ultra-wide band signal pulses completely are intercepted out with signal window；Wherein, the size of signal window is
Emit twice of signal width；
Step 3：Wavelet transformation is carried out to the ultra-wide band signal pulses after interception；
Step 4：High-pass filtering is carried out to the ultra-wide band signal pulses after wavelet transformation, to obtain the letter containing spike
Number, which includes two signal peaks and two interference spikes；
Step 5：Counter sets k=1；
Step 6：The spike where k-th of maximum value of signal of spike is searched for, and determines its time-domain position；
Step 7：Spike is extracted with signal window at the time-domain position；The signal window size should be not less than point
The width at peak, signal window center are the center of the spike；
Step 8：The signal peaks of extraction are related to the template signal of correlation receiver；It is predefined if correlation is more than
Threshold value, then the spike be signal peaks, available for making conclusive judgement, flow terminates；Otherwise, this is a false-alarm, spike
It is noise, needs to abandon, and continue to execute step 9；
Step 9：If k is less than preset secondary numerical value of N, k=k+1 is enabled, step 6 is transferred to and continues to execute；Otherwise ultra-wide
Band signal pulse may be not present, and be transferred to step 1 and re-search for.
In an embodiment of the present invention, the concrete mode of the step 3 is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, what is be disturbed is super
Wideband signal pulses can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 },
ciRepresent the amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
In an embodiment of the present invention, the Amplitude Ration of the signal peaks and interference spike is equal to signal pulse and interference arteries and veins
The Amplitude Ration of punching, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
In an embodiment of the present invention, the signal peaks and interference spike between time delay be equal to signal pulse with
Delay time between disturbing pulse.
Compared to the prior art, the invention has the advantages that：
(1) without using the digital analog converter of conversion rate superelevation, ultra-broadband signal is overcome because bandwidth superelevation digital-to-analogue turns
Change difficult obstacle；
(2) channel information need not be collected or carry out complicated channel estimation, without carrying out the equal of complexity and rate superelevation
Weighing apparatus operation；
(3) the intersymbol interference elimination algorithm designed by can fight the interference of any number of mixing multipath signals；
(4) the intersymbol interference elimination algorithm step designed by is succinctly apparent, convenient and efficient；
(5) the intersymbol interference elimination algorithm avoids the propagation of error without decision-feedback；
(6) intersymbol interference elimination algorithm designed by is not by limitations such as ultra-broadband signal waveform and receiver modules, just
In popularization and application；
(7) the intersymbol interference elimination algorithm designed by has the false-alarm judgement under multipath noise channel, antinoise
And the robustness of multipath is high.
Description of the drawings
Fig. 1 interferes the receiver module of elimination between ultra-wideband impulse radio signal code.
Fig. 2 is the simulation of ultra-wideband impulse signal wireless channel transmission indoors, and the repetition period for sending signal is 10ns.
Fig. 3 is the waveform of each correlation function after wavelet transformation and high-pass filtering, wherein 3 (a) is f (u) waveforms, 3 (b) is Ω
(u) waveform, 3 (c) are g (u) waveforms, and 3 (d) is Δ (u) waveform, and 3 (e) is W (u) waveforms, and 3 (f) isWaveform；Parameter value
A=0.008 and tc=2.5.
Fig. 4 is the system framework figure of intersymbol interference ISI cancellation schemes under ultra-wideband impulse radio multipath noise channel.
Fig. 5 is the embodiment that ultra-wideband impulse radio intersymbol interference is eliminated under noiseless multipath channel, wherein, 5
(a) it is ultra-wide band signal pulses s (t), mixed pulses (having ISI) r (t) of disturbing pulse i (t) and the two；5 (b) is works as a=
0.008 and tcWavelet transformation waveform W when=2.5r(u)；5 (c) is spike5 (d) isSpike portion
Divide amplification, time window center is us1；5 (e) is the spiking λ (u) extracted；5 (f) believes for correlation receiver template
Number q (u-us1)。
Specific embodiment
Below in conjunction with the accompanying drawings, technical scheme of the present invention is specifically described.
The system of ultra-broadband signal intersymbol interference under a kind of elimination multipath noise channel of the present invention, including
Signal search module for searching for the ultra-wide band signal pulses higher than predetermined threshold value, and determines its time-domain position；
Signal window module completely intercepts the ultra-broadband signal arteries and veins of the signal search block search using signal window
Punching, the signal window size are emit signal width twice；
ISI arresters, for eliminating ultra-wide band signal pulses intersymbol interference, i.e., to the signal window module intercepts
Ultra-wide band signal pulses carry out wavelet transformation, then, high-pass filtering are carried out to the ultra-wide band signal pulses after wavelet transformation, to obtain
Take signal containing spike, then and, k-th of maximum value of the signal of the spike is searched for, and determine its time-domain position, at the beginning of k
Beginning takes 1, then, extracts the signal peaks of the signal containing spike by signal window in the time-domain position, is sent to
Receiver module；
Receiver module and judging module receive the signal peaks for the signal containing spike for sending ISI arresters, and
The signal peaks are related to template signal progress, if correlation is more than predetermined threshold value, which is required
Signal peaks, and make decisions, the signal peaks are otherwise abandoned, and judge whether k is less than preset N, if being less than, k+
1, and signal peaks are extracted again through ISI arresters, until the correlation of number spike of extraction and template signal is more than in advance
Determining threshold value, then makes decisions.
The concrete mode that the ultra-wide band signal pulses of the signal window module intercepts are carried out with wavelet transformation is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, what is be disturbed is super
Wideband signal pulses can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 },
ciRepresent the amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
The signal containing spike includes two signal peaks and two interference spikes.The signal peaks and interference point
The Amplitude Ration at peak is equal to the Amplitude Ration of signal pulse and disturbing pulse, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
Time delay between the signal peaks and interference spike is equal to the delay between signal pulse and disturbing pulse
Time.
It is described to be used in the time-domain position is extracted the signal peaks of the signal containing spike by signal window
Signal window size should be not less than signal peaks width.
The present invention also provides a kind of method for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, including such as
Lower step,
Step 1：Search is higher than the ultra-wide band signal pulses of predetermined threshold value, and determines its time-domain position.
Step 2：Ultra-wide band signal pulses completely are intercepted out with signal window；Wherein, the size of signal window is
Emit twice of signal width；
Step 3：Wavelet transformation is carried out to the ultra-wide band signal pulses after interception；
Step 4：High-pass filtering is carried out to the ultra-wide band signal pulses after wavelet transformation, to obtain the letter containing spike
Number, which includes two signal peaks and two interference spikes；
Step 5：Counter sets k=1；
Step 6：The spike where k-th of maximum value of signal of spike is searched for, and determines its time-domain position；
Step 7：Spike is extracted with signal window at the time-domain position；The signal window size should be not less than point
The width at peak, signal window center are the center of the spike；
Step 8：The signal peaks of extraction are related to the template signal of correlation receiver；It is predefined if correlation is more than
Threshold value, then the spike be signal peaks, available for making conclusive judgement, flow terminates；Otherwise, this is a false-alarm, spike
It is noise, needs to abandon, and continue to execute step 9；
Step 9：If k is less than preset secondary numerical value of N, k=k+1 is enabled, step 6 is transferred to and continues to execute；Otherwise ultra-wide
Band signal pulse may be not present, and be transferred to step 1 and re-search for.
The concrete mode of the step 3 is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, what is be disturbed is super
Wideband signal pulses can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 },
ciRepresent the amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
The Amplitude Ration of the signal peaks and interference spike is equal to the Amplitude Ration of signal pulse and disturbing pulse, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
Time delay between the signal peaks and interference spike is equal to the delay between signal pulse and disturbing pulse
Time.
Specific implementation process for the present invention below.
It is as follows that the system and method interfered between ultra-wideband impulse radio signal code is eliminated the present invention is based on wavelet transformation：
(1) system model
1st, system model and receiver module
Used ultra-wideband impulse radio model of communication system is as shown in Figure 1.UWB pulses are through BPSK (binary system phases
Move keying) it modulates and is sent by wireless channel.For the ease of analysis, the receiver module of gating technology is employed, that is, is passed through
Suitable threshold value is set, and searcher receiver receives signal, is to detect successfully until signal level is more than threshold value.Then, using letter
The extraction of number window receives signal, and by the composite signal pulse detected (by signal pulse and more than one multipath interference signal
Mix) it is placed on the centre of signal window.Receiving signal before demodulation will be done by intersymbol proposed by the invention
The processing of ISI arresters is disturbed, to remove intersymbol interference.Specifically, the application of the ISI arresters is not by this receiver
The limitation of model.
2nd, ultra-wideband impulse model
UWB pulses use Gaussian monopulse model：
Wherein A is constant collection, meets FCC (US Federal Communication Committee Federal Communications
Commission) to the requirement of ultra-broadband signal, centre frequency is selected as fc=6.85GHz.
3rd, UWB wireless channel models
The present invention uses the UWB wireless multi-path channels models of IEEE802.15.4a, and assumes there is direct-view (Line of
Sight, abbreviation LOS) path.The UWB pulses emulation transmitted on this channel is as shown in Figure 2.Propagate the pulse repetition period be
10ns.Due to the ultra wide bandwidth of UWB pulses, there is a large amount of multi-path component for the pulse of each transmission in receivers.
As can be seen that due to relatively large delay transit (being more than 10 ns), intersymbol interference is resulted in.The pulse of reception is by elder generation
The multi-path component of the pulse of preceding transmission is interfered.The signal window in Fig. 2 upper right corner more clearly illustrates this point.
4th, UWB impulse models are normalized
Succinct to analyze, the normalization of UWB impulse models is as follows：It enablesIt is and fixed
P (t) is the first derivative of Gaussian pulse, and the UWB pulse durations of actual transmissions are limited.Therefore, it adopts here
It is the Gaussian pulse first derivative of time-domain finite with normalized UWB impulse models
Starting point and terminal are located at t=-t respectivelycAnd t=tc.It is 2t to emit signal widthc。
5th, intersymbol interference ISI models
For the ease of illustrating, and without loss of generality, ISI models consider as follows.UWB pulses are modulated through BPSK, receive termination
The UWB signal pulse received is
S (t)=dscsp(t)
Wherein useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse (straight length) s (t).It is another
One pulse i (t) interference, this is other multipath components of UWB pulses, i.e.,
I (t)=dicip(t-t0)
Wherein interference data di∈ {+1, -1 }, ciRepresent the amplitude of disturbing pulse i (t), t0It is the interval of s (t) and i (t)
Time.This model can be easy to expand to multiple disturbing pulses.
According to mean power attenuation curve, the mean power of pulse multiplex diameter component is particularly deposited with the rapid attenuation of delay
In the environment of straight length.Therefore, in the multipath channel ISI models there are straight length, the amplitude of disturbing pulse is less than
The amplitude of signal pulse, i.e. ci＜ cs。
(2) theory analysis
Intersymbol interference ISI cancellation schemes proposed by the present invention be based on wavelet transformation, have studied ultra-wideband pulse without
The characteristic of line electric signal (the limited first derivative of Gaussian pulse) wavelet transformation.It (is also referred to as by using the first derivative of Gaussian function
For single order Gauss wavelet) as morther wavelet, the wavelet transformation of ultra-wideband impulse radio signal p (t) is in time u (scale factor
For a and a ＜ ＜ 1) be
It can be obtained by correlation derivation
W (u)=Ω (u)+Δ (u)
Wherein：
Δ (u)=g (tc+u)+g(tc-u)
Wherein f (u) is referred to Ω (u) waveforms shown in Fig. 3 (a) and (b).Function g (u) main genes areBecause of a ＜ ＜ 1, g
(u) the Gaussian pulse spike and center substantially compressed is located at u=0, refers to Fig. 3 (c).Due to Δ (u)=g (tc+u)+g(tc-
U), therefore its waveform is beginning and end that two spikes concentrate on original signal pulse, i.e. u=-tcAnd u=tc, such as Fig. 3 (d)
It is shown.W (u) waveforms refer to Fig. 3 (e).High-pass filter can be used to extract signal peaks from W (u).The result of high-pass filteringRefer to Fig. 3 (f).One timing of fire pulse width, the width of the controllable signal peaks of selection of wavelet transform dimension factor a
With amplitude height.Value a=0.008 and t in the present inventionc=2.5.
1st, without the wavelet transformation property analysis that signal is received in the case of ISI
Ultra-wide band signal pulses s (t)=d is considered firstscsP (t) and without ISI situations, the wavelet transformation of s (t) is
Ws(u)=dscsW (u)=Ωs(u)+Δs(u)
Wherein
Δs(u)=dscsΔ(u) (2)
And
Ωs(u)=dscsΩ(u)
According to the analysis of front it is understood that signal peaks Δs(u) Gaussian pulse for two change of scale, by formula (1)
Following characteristic can be released：
Characteristic 1：The symbol of signal peaks is consistent with the symbol of signal pulse；
Characteristic 2：The amplitude of signal peaks and the amplitude of signal pulse are directly proportional；
Therefore it can use signal peaks that the signal received is replaced to be demodulated and detect.Due toIt is g (u)
Main gene enables
The as template signal of correlation receiver.
2nd, there is the wavelet transformation property analysis that signal is received under ISI and noise situations
Consider the situation of ISI now, that is, the UWB signal pulse received is interfered the influence of pulse.What is received answers
Closing pulse can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein n (t) is white Gaussian noise.It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
For convenience, it is known as interfering spike by the spike that disturbing pulse generates.It should be pointed out that front derived
Two characteristics of signal peaks are also applied for interference spike.Since wavelet transformation is linearly invariant, by (3) formula, we can push away
Go out two useful properties：
Property 1：The Amplitude Ration of signal peaks and interference spike is equal to the Amplitude Ration of signal pulse and disturbing pulse, i.e.,
Property 2：Time delay between signal peaks and interference spike is equal to prolonging between signal pulse and disturbing pulse
The slow time.
Because spike is more much narrower than former pulse, so signal peaks are disturbed spike and interfere the probability obscured very low.Since
The composite pulse (containing intersymbol interference ISI) that direct demodulation/detection receives can lead to larger error rate, it may be considered that profit
It is demodulated/is detected with signal peaks.
The wavelet transformation W of noisen(u) or noise, as long as the noise would not influence signal peaks less than signal peaks
Detection.System will appear false-alarm when noise amplitude is higher, but noise in irregular shape is related to Gaussian pulse template
A very low correlation will be generated.Therefore, most false-alarm can be removed.In addition, by the expression formula of (1) g (u) it is found that
It can enable it as far as possible higher than noise by adjusting the size of wavelet transform dimension factor a come the amplitude of promotion signal spike
Average value further promotes noise resisting ability.
(3) under multipath noisiless channel ultra-broadband signal ISI elimination algorithms
More than theory analysis is based on, we have proposed ISI under a kind of new impulse radio multipath noisiless channel to eliminate
The system of device, system block diagram are as shown in Figure 4.After wavelet transformation and high-pass filtering processing, the signal pulse that receives with
The composite pulse that disturbing pulse is formed has been melted into four spikes.
Can be pushed away from signal peaks characteristic 2, the amplitude of spike is bigger, corresponding to UWB pulse signal width
Value is bigger.Therefore, according to the channel model (there are straight lengths) of UWB multipaths, in four spikes, amplitude maximum
Two can be speculated as signal peaks, and remaining two are then interference spikes.Signal peaks can be used for it is subsequent demodulation and
Detection.
To tackle noise, special consideration should be given to the processing of false-alarm for the ISI elimination algorithms of ultra-broadband signal under noise circumstance.Specifically
Algorithm is as follows：
Step 1：Search is higher than the reception signal of predetermined threshold value, and determines its time-domain position.
Step 2：It intercepts out with receiving signal integrity with signal window.Wherein, the size of signal window is believed for transmitting
Twice of number width.
Step 3：Wavelet transformation is carried out to the reception signal after interception.
Step 4：High-pass filtering is carried out to the above-mentioned signal after wavelet transformation, to obtain the signal containing spike, is paid attention to
Spike herein includes two signal peaks and two interference spikes.
Step 5：Counter sets k=1.
Step 6：The spike where above-mentioned k-th of maximum value of signal is searched for, and determines its time-domain position.
Step 7：Spike is extracted with signal window at the time-domain position.Here signal window size should not be small
In the width of spike, signal window center is the center of the spike.
Step 8：The spike of extraction is related to the template signal of correlation receiver.
If correlation is more than predetermined threshold value, which is signal peaks, available for making conclusive judgement, is flowed
Journey terminates.
Otherwise, this is a false-alarm, and spike is noise, needs to abandon, and continue to execute step 9.
Step 9：If k is less than preset secondary numerical value of N, k=k+1 is enabled, step 6 is transferred to and continues to execute；Otherwise it receives
Signal may be not present, and be transferred to step 1 and re-search for.
It should be noted that step 9 increases recycling-guard mechanism, due to can be by adjusting wavelet transform dimension a etc.
Parameter allows signal peaks amplitude to be higher than white Gaussian noise average amplitude, and signal peaks will soon search, therefore secondary numerical value of N is general
For 10 enough.
(4) embodiment
The embodiment that ultra-wideband impulse radio intersymbol interference is eliminated under noisy multipath channel is as shown in Figure 5.
Corresponding to ISI elimination algorithms, the result of step 1 is shown in Fig. 5 (a), r (t) be receive have noise and symbol
Between interfere ISI composite pulse.The signal of r (t) and noise interference (SNIR) are 1.82dB.R (t) and correlation receiver template
The correlation of signal is only 0.67.The result of corresponding wavelet transformation and high-pass filtering is respectively illustrated in Fig. 5 (b) and (c).a
=0.008 and tc=2.5.The distance between transmitter and receiver are 10 meters.The amplitude c of disturbing pulsei=0.8csAnd when
Between postpone t0=1.5.ds=di=1.During ISI is eliminated, a false-alarm (noise), the signal and mould are shown in Fig. 5 (e)
Plate correlation generates a low correlation (0.27), is abandoned by ISI elimination algorithms.Fig. 5 (d) shows the signal point eventually detected
(temporal center position is u at peaks), 0.95 is up to template signal correlation, corresponding signal is carried with noise interference SNIR
Height is substantially improved compared to 1.82dB before, improves apparent to 8.22dB.Fig. 5 (f) is the template signal q of correlation receiver
(u-us).Correlation receiver judges that the threshold value of false-alarm takes 0.5 in the present embodiment.
For there is the reception signal of ISI interference and noise, if not receiving signal using intersymbol interference arrester
It can become very poor with the correlation of template, when particularly interference signal is opposite with useful signal symbol.And this hair is used
After bright ISI arresters the correlation of correlation receiver can close to 1, signal and noise interference SNIR be improved significantly,
Communication system performance has obtained great promotion.
The above are preferred embodiments of the present invention, all any changes made according to the technical solution of the present invention, and generated function is made
During with range without departing from technical solution of the present invention, all belong to the scope of protection of the present invention.
Claims (10)
1. a kind of system for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, it is characterised in that：Including
Signal search module for searching for the ultra-wide band signal pulses higher than predetermined threshold value, and determines its time-domain position；
Signal window module completely intercepts the ultra-wide band signal pulses of the signal search block search using signal window,
The signal window size is emit signal width twice；
ISI arresters, for eliminating ultra-wide band signal pulses intersymbol interference, the i.e. ultra-wide to the signal window module intercepts
Band signal pulse carries out wavelet transformation, then, carries out high-pass filtering to the ultra-wide band signal pulses after wavelet transformation, is contained with obtaining
Spike signal, then and, k-th of maximum value of the signal of the spike is searched for, and determine its time-domain position, k initially takes
1, then, the signal peaks of the signal containing spike are extracted by signal window in the time-domain position, are sent to reception
Machine module；
Receiver module and judging module receive the signal peaks for the signal containing spike for sending ISI arresters, and should
Signal peaks are related to template signal progress, if correlation is more than predetermined threshold value, which is desired signal
Spike, and make decisions, the signal peaks are otherwise abandoned, and judge whether k is less than preset N, if being less than, k+1, and
Signal peaks are extracted again through ISI arresters, are predefined until the correlation of number spike of extraction and template signal is more than
Threshold value, then make decisions.
2. the system according to claim 1 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：The concrete mode that the ultra-wide band signal pulses of the signal window module intercepts are carried out with wavelet transformation is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, the ultra wide band that is disturbed
Signal pulse can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Ωi(u)=diciΩ(u-t0),Δi(u)=diciΔ(u-t0)
Δ (u)=g (tc+u)+g(tc-u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 }, ciIt represents
The amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
3. the system according to claim 2 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：The signal containing spike includes two signal peaks and two interference spikes.
4. the system according to claim 3 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：The Amplitude Ration of the signal peaks and interference spike is equal to the Amplitude Ration of signal pulse and disturbing pulse, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
5. the system according to claim 3 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：When time delay between the signal peaks and interference spike is equal to the delay between signal pulse and disturbing pulse
Between.
6. the system according to claim 1 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：The letter used in the time-domain position is extracted the signal peaks of the signal containing spike by signal window
Number window size should be not less than the width of signal peaks.
A kind of 7. method for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, it is characterised in that：Including walking as follows
Suddenly,
Step 1：Search is higher than the ultra-wide band signal pulses of predetermined threshold value, and determines its time-domain position.
Step 2：Ultra-wide band signal pulses completely are intercepted out with signal window；Wherein, the size of signal window is transmitting
Twice of signal width；
Step 3：Wavelet transformation is carried out to the ultra-wide band signal pulses after interception；
Step 4：High-pass filtering is carried out to the ultra-wide band signal pulses after wavelet transformation, it, should to obtain the signal containing spike
Spike includes two signal peaks and two interference spikes；
Step 5：Counter sets k=1；
Step 6：The spike where k-th of maximum value of signal of spike is searched for, and determines its time-domain position；
Step 7：Spike is extracted with signal window at the time-domain position；The signal window size should be not less than spike
Width, signal window center are the center of the spike；
Step 8：The signal peaks of extraction are related to the template signal of correlation receiver；If correlation is more than predetermined threshold
Value, then the spike is signal peaks, and available for making conclusive judgement, flow terminates；Otherwise, this is a false-alarm, and spike is to make an uproar
Sound needs to abandon, and continues to execute step 9；
Step 9：If k is less than preset secondary numerical value of N, k=k+1 is enabled, step 6 is transferred to and continues to execute；Otherwise ultra-wide is taken a message
Punching of feeling the pulse may be not present, and be transferred to step 1 and re-search for.
8. the method according to claim 7 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, feature
It is：The concrete mode of the step 3 is as follows,
Consider the situation of ISI, that is, the ultra-wide band signal pulses received be interfered pulse influence when, the ultra wide band that is disturbed
Signal pulse can be expressed as
R (t)=s (t)+i (t)+n (t)
Wherein, s (t) is signal pulse, and i (t) is disturbing pulse, and n (t) is white Gaussian noise；
It is obtained by wavelet transformation
Wr(u)=Ws(u)+Wi(u)+Wn(u)
Wherein：
Ws(u)=dscsW (u)=Ωs(u)+Δs(u),Δs(u)=dscsΔ(u),Ωs(u)=dscsΩ(u)
Ωi(u)=diciΩ(u-t0),Δi(u)=diciΔ(u-t0)
Δ (u)=g (tc+u)+g(tc-u)
Useful signal data ds∈ {+1, -1 }, csRepresent the amplitude of signal pulse s (t)；Interfere data di∈ {+1, -1 }, ciIt represents
The amplitude of disturbing pulse i (t)；t0It it is the interval time of s (t) and i (t), a is scale factor and a ＜ ＜ 1.
9. the method according to claim 7 or 8 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel, special
Sign is：The Amplitude Ration of the signal peaks and interference spike is equal to the Amplitude Ration of signal pulse and disturbing pulse, i.e.,
Wherein, csRepresent the amplitude of signal pulse, ciRepresent the amplitude of disturbing pulse.
10. the method according to claim 7 or 8 for eliminating ultra-broadband signal intersymbol interference under multipath noise channel,
It is characterized in that：Time delay between the signal peaks and interference spike is equal to the delay between signal pulse and disturbing pulse
Time.
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