CN105681323B - A kind of Information hiding formula radio transmitting method based on time reversal - Google Patents
A kind of Information hiding formula radio transmitting method based on time reversal Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L63/00—Network architectures or network communication protocols for network security
- H04L63/04—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks
- H04L63/0428—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks wherein the data content is protected, e.g. by encrypting or encapsulating the payload
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Abstract
The invention discloses a kind of Information hiding formula radio transmitting method based on time reversal, belongs to electronic technology field.The present invention emits wideband-short pulse A (t), obtains the time domain cape signal C (t) shunk through processing；The pulse of coding or train of pulse S (t) are emitted, apart time interval is Δ t by signal Y (t), S (t) and C (t) all the way with C (t) synthesis；Y (t) is sent into the first reverberation chamber, forms new signal Z (t) through processing；Z (t) is emitted, is received after free space by receiving end；In receiving end, Z (t) waveform is done into time inversion, obtains signal Z (- t)；Inverting mixed signal Z (- t) is sent into the second reverberation chamber, signal O (t) is obtained, O (- t) is obtained after time inversion.Through the above scheme, the present invention realizes the concealed transmission of information, is used in secret communication field.
Description
Technical field
The invention belongs to person in electronics, and in particular to a kind of Information hiding formula wireless transmission side based on time reversal
Method.
Background technique
With the continuous development of society with the continuous renewal of science and technology, the information content of people's contact is also increasing, letter
Breath transmitting is also enriched constantly with the means obtained.Wireless messages are current widest communication mode, in wireless communications, communication
Confidential information is intercepted in order to prevent between object, it is necessary to by the method encoded information arranged in advance, allow information disguising, or
It is communicated in a manner of its hidden true content.In message transmitting procedure, transmitting terminal just needs the information to required transmission
It is encrypted, changes the form of expression of original information, hide real information；In receiving end, according to prior agreement, to hiding
Real information carries out DecryptDecryption processing, restores raw information.In this way, not known about representated by signal even if listener-in can receive yet
The information content.
However, with the continuous development of electronic information technology, the especially raising of computer technology, to by using number letter
Cracking for number processing technique encryption information is ery easy.See as much cell phone application is soft at present, so that it may which moment cracks hotspot
(WIFI) password, causes damages.Therefore, the new mechanism of one kind can be found to encrypt information, prevent information from transmitting
It is stolen in the process, is a significant research topic.Such as 2010, J.M.Lukens was at famous academic journal " Nature "
On delivered entitled " Atemporalcloakattelecommunicationdatarate " (Nature, vol.498,205-
208,2013) article elaborates using chirp delay technology, the method for the stealthy cape of manufacturing time (Temporalcloak),
It allows Information hiding in time cape, realizes the concealed transmission of information, realize secret communication.This method is based on pure physical machine
System is not necessarily to Digital Signal Processing, and listener-in can not obtain encryption information, therefore prevent the leakage of information.
Time reversal electromagnetism is a new electromagnetism subject branch.Herein, when so-called time reversal is not
Light is flow backwards, but the inverting moved.For Electromagnetic Wave Propagation, be exactly by received time domain electromagnetic signal waveform when
Between do mirror image on axis, the process then emitted again.With time reversal electromagnetic theory become better and approaching perfection day by day and signal processing technology
Continuous renewal, being with a wide range of applications for the superior space-time adaptive filtering characteristic of time reversal electromagnetic wave can solve
Certainly perplex some problems of traditional electromagnetic theory many years.The electromagnetism time reversal system of complete set is divided into two parts, and first
It is divided into time reversal mirror system (Timereversalmirror, TRM), second part is reception system.The effect of TRM is will to connect
The channel signal received carries out time reversal inversion, then waveform obtained is inverted to and carried out coding or shaping, weight
New transmitting.The effect of reception system is launch channel detectable signal, and receives the inverting signal emitted by TRM, at itself
It obtains to focus and wash.2004, G.lerosey et al. delivered entitled " TimeReversalofelectromagneticwaves "
(Phys.Rev.Lett., vol.92, pp.1939041), text in for the first time to the sky of time reversal electromagnetic wave when synchronizing focus characteristic
It elaborates.Entitled " Focusing is delivered in authoritative academic journal " Science " in G.Lerosey in 2007 et al.
beyongthediffractionlimitwithfar- fieldtimereversal,”(Science,vol.315,
Pp.1119-1122, Feb.2007.), text in obtain time reversal electromagnetic wave far field super-resolution rate sub-wavelength focus characteristics into
Gone introduction, and give experiments have shown that.2013, fourth general et al. delivered entitled " Sub- wavelengtharraywithem
beddedchirpeddelaylinesbasedontimereversaltechnique”(IEE
ETrans.AntennasPropag., vol.61, no.5, pp.2868-2873), it proposes to utilize dispersion encoding channel, when acquisition
Between inverting sub-wavelength focus mode.2015, fourth general et al. delivered entitled " Enhancementoftimereversalsubw
avelengthwirelesstransmissionusingpulseshaping ”(IEEETrans.AntennasPropag.,
Vol.63, no.9, pp.4169-4174), it is proposed that the method that time reversal super-resolution focus is obtained based on pulse-shaping technique.
Summary of the invention
The purpose of the present invention is intended to the time domain focus characteristics using time reversal, creates time cape, makes signal to be transmitted
It can hide wherein, realize the purpose of secrecy wireless transmission.
To achieve the goals above the invention adopts the following technical scheme:
A kind of Information hiding formula radio transmitting method based on time reversal, which comprises the following steps:
(1) emit wideband-short pulse A (t), do Linear Amplifer through power amplifier, obtain the time domain cape signal C of contraction
(t)；
(2) pulse of coding or train of pulse S (t) are emitted, synthesizes signal Y (t)=C (t)+S (t), S all the way with C (t)
It (t) is Δ t at a distance of time interval with C (t)；
(3) Y (t) is sent into the first reverberation chamber, due to multipath effect, cape signal C (t) wave distortion is stretched, and is formed
Noise signal N (t), and the signal S (t) for carrying information is fallen into oblivion, form new signal Z (t)；
(4) Z (t) is emitted, is received after free space radio channel by receiving end；
(5) in receiving end, Z (t) waveform is done into time inversion, obtains signal Z (- t)；
(6) the signal Z (- t) after inverting is sent into the second reverberation chamber, the inverting noise signal N (- t) of expansion gathers again
Coke, the information being hidden in cape are restored.In above-mentioned technical proposal, the time domain response of reverberation chamber can be expressed as,
Wherein, N is the quantity of multipath, aiFor the amplitude factor of the i-th paths, δ (t- Δ ti) be the i-th paths impact
Response, Δ tiFor the time delay of the i-th paths.
In above-mentioned technical proposal, in step (3):
In above-mentioned technical proposal, the expression formula of Z (- t) in step (5) are as follows:
In above-mentioned technical proposal, in step (6)
The present invention because use above-mentioned technical proposal, have it is following the utility model has the advantages that
The present invention obtains higher secure wireless communication, and the Information hiding transmitted will be needed in artificial environment noise
In, and by time reversal technology, it is realized in receiving end and the waveform for being hidden in Signal in Noise is restored, with noise signal
It is separated, to realize the hidden wireless transmission of information, achievees the effect that secrecy transmission.
Detailed description of the invention
Fig. 1 is basic block diagram of the present invention.
Fig. 2 be the present invention-embodiment in echo signal in conjunction with the cape signal of contraction after waveform.
Fig. 3 is the reverberation cavity in the present invention-embodiment；
Fig. 4 is that cape signal is unfolded in the present invention-embodiment, hides the waveform of echo signal.
Fig. 5 is the signal waveform after restoring in the present invention-embodiment.
Marked in the figure: 1- impulse generator, 2- power amplifier, 3- power combiner, 4- reverberation chamber, 5- power amplification
Device, 6- transmitting terminal antenna, 7- free space radio channel, the low dispersive-antenna in the broadband 8-, 9- filter, 10- low noise amplification
Device, 11- time reversal module, 12- reverberation chamber, 13- receive terminal.
Specific embodiment
All features disclosed in this specification or disclosed all methods or in the process the step of, in addition to mutually exclusive
Feature and/or step other than, can combine in any way.
It elaborates below with reference to Fig. 1-5 couples of present invention.
A kind of Information hiding formula transmission method based on time reversal, scheme following sections as shown in Figure 1, be made of:
1. impulse generator 1, for emitting cape pulse A (t).
2. power amplifier 2 amplifies cape pulse for amplitude, obtains signal C (t).
3. power combiner 3, for signal to be transmitted X (t) and amplified cape pulse signal to be combined into signal all the way.
4. reverberation chamber 4.For amplified cape signal waveform to be carried out multidiameter, the mistake of duration of run cape is realized
Journey manufacturing environment noise.
5. power amplifier 5, for amplifying cape signal and echo signal after being unfolded, for emitting signal.
6. transmitting terminal antenna 6, for emitting signal.
7. free space radio channel 7.
8. the low dispersive-antenna 8 in broadband.
9. filter 9.
10. low-noise amplifier 10.
11. time reversal module 11, the signal waveform received for inverting.
12. reverberation chamber 12.There is identical time domain response with reverberation chamber 4, for restoring waveform.
13. receiving terminal 13.
Its course of work is to have following steps:
(1) impulse sender transmitting pulse A (t).
(2) A (t) amplifies after amplifier, obtains cape signal C (t), with signal to be transmitted X (t) in power combiner
It is combined into signal Y (t) all the way.
(3) Y (t) is sent into chaos reverberation chamber.In chaos reverberation chamber, cape signal C (t) waveform changes, shape
At cape signal N (t), while multipath effect can also occur for signal to be transmitted, form new signal M (t), due to the amplitude of M (t)
Less than N (t), therefore, M (t) is fallen into oblivion with cape signal N (t), forms new signal Z (t).
(4) Z (t) is emitted by transmitting antenna, through free space radio dissemination channel, is received by receiving antenna.
(5) the signal Z (t) received is sent into time reversal module, is obtained waveform inversion signal Z (- t).
(6) Z (- t) is sent into chaos reverberation chamber, since time reversal electromagnetic wave is to the compensating action of multipath effect, ring
Border cape signal focuses respectively with measured signal, and can be distinguish.
In step (2), realize as the process of signal to be transmitted setup time cape.At this point, the state of time cape
For contraction state.In contraction state, cape signal and signal to be transmitted can be differentiated by amplitude.
In step (3), time cape opening is realized, the process of echo signal is covered, when realizing to echo signal
The stealthy operation in domain.
In step (5), the under operation to time cape is realized.
In step (6), the shrinkage operation of time cape is realized.At this point, the state of time cape is contraction state, to
Emit signal and cape Signal separator, is displayed from time cape.
Embodiment 1
Step 1, a pulse signal A (t) is emitted by impulse generator 1.Impulse generator shown in Fig. 1 can be by photoconductive switch
Or arbitrary waveform generator is realized.
Step 2, pulse signal A (t) is sent into power amplifier 2, obtains cape signal C (t).At this point, cape is believed
Number C (t) and echo signal S (t) is through power combiner 3, synthesis signal Y (t) all the way, as shown in Figure 2.The mathematics of signal Y (t)
Expression formula is,
Y (t)=C (t)+S (t) (1)
Step 3, synthesized signal Y (t) is sent in reverberation chamber 4 shown in Fig. 3.In this embodiment, reverberation chamber size is
A=40cm, b=40cm, c=70cm.Since reverberation chamber is a multidiameter structure, time domain response can be expressed as,
Wherein, N is the quantity of multipath, aiFor the amplitude factor of the i-th paths, δ (t- Δ ti) be the i-th paths impact
Response, Δ tiFor the time delay of the i-th paths.After Y (t) is sent into reverberation chamber, multidiameter effect can occur for signal, export Z
(t).Z (t) are as follows:
In above formula, * is convolution symbol, and N (t) is the signal that the C (t) in (1) formula is obtained with H (t) convolution, and M (t) is (1)
The signal that S (t) and H (t) convolution in formula are obtained.
Since cape signal amplitude is higher than echo signal, in the cape signal after multidiameter, after waveform diffusion
Echo signal can be covered, is covered in a time cape similar to by echo signal, as shown in Figure 4.
Step 4, Z (t) is amplified into again transmitting terminal antenna 6 by power amplifier 5 and is radiated to free space radio channel 7
In.Transmitting terminal antenna can be the broadband Vivaldi antenna or butterfly antenna of low dispersion, to guarantee that waveform is undistorted.
Step 5, in receiving end, the signal transmitted by transmitting terminal is received using the low dispersive-antenna 8 in broadband, and be sent into filter
9 filter out noise signal, after the amplification of low-noise amplifier 10, are sent into time reversal module 11, deadline inversion obtains
Z(-t).The expression formula of Z (- t) are as follows:
Step 6, time reversal signal Z (- t) is sent into reverberation chamber 12 identical with reverberation chamber 4, gained signal are as follows:
It can be seen that the compensation due to time reversal to multipath effect in formula (5), cape signal and input signal are extensive
It appears again and.From the point of view of waveform as shown in Figure 5, cape signal is shunk again, and input signal is showed again.It is completed in receiving end
The process that waveform restores, realizes the concealed transmission of signal.
Claims (6)
1. a kind of Information hiding formula radio transmitting method based on time reversal, which comprises the following steps:
(1) emit wideband-short pulse A (t), do Linear Amplifer through power amplifier, obtain the time domain cape signal C (t) of contraction；
(2) pulse of coding or train of pulse S (t) are emitted, synthesizes signal Y (t)=S (t)+C (t), S (t) and C all the way with C (t)
It (t) is Δ t at a distance of time interval；
(3) Y (t) is sent into the first reverberation chamber, due to multipath effect, cape signal C (t) wave distortion is stretched, and forms noise
Signal N (t), and the signal S (t) for carrying information is fallen into oblivion, form new signal Z (t)；
(4) Z (t) is emitted, is received after free space radio channel by receiving end；
(5) in receiving end, Z (t) waveform is done into time inversion, obtains signal Z (- t)；
(6) inverting mixed signal Z (- t) is sent into the second reverberation chamber, obtains signal O (t), O is obtained after time inversion
(-t)。
2. a kind of Information hiding formula radio transmitting method based on time reversal according to claim 1, which is characterized in that
The time domain response of reverberation chamber is expressed as,
Wherein, N is the quantity of multipath, aiFor the amplitude factor of the i-th paths, δ (t- Δ ti) be the i-th paths shock response,
ΔtiFor the time delay of the i-th paths.
3. a kind of Information hiding formula radio transmitting method based on time reversal according to claim 2, which is characterized in that
In step (3):
(2) in formula, the noise signal that N (t) is C (t) and H (t) convolution obtains, the distortion that M (t) is S (t) and H (t) convolution obtains
Carrying information signal, C (t- Δ ti) it is the delayed Δ t of cape signaliSignal after time, S (t- Δ ti) it is to carry information
Pulse or the delayed Δ t of burst signaliSignal after time.
4. a kind of Information hiding formula radio transmitting method based on time reversal according to claim 3, which is characterized in that
The expression formula of Z (- t) in step (5) are as follows:
(3) in formula, N (- t) is the time reversal signal of N (t), and meaning is the noise signal after waveform reversion, and M (- t) is M
(t) time reversal signal, meaning are the signal of the carrying information of the distortion after waveform reversion, C (- t- Δ ti) meaning be
The delayed time Δ t of the cape signal of time reversaliSignal afterwards, S (- t- Δ ti) meaning be time reversal carrying information
Pulse or the delayed time Δ t of burst signaliSignal afterwards, N are the quantity of multipath, aiFor the i-th paths amplitude because
Son, Δ tiFor the time delay of the i-th paths.
5. a kind of Information hiding formula radio transmitting method based on time reversal according to claim 1, which is characterized in that
In step (6)
Wherein, H (t) is the time domain response of reverberation chamber, and N is the quantity of multipath, aiFor the amplitude factor of the i-th paths, ajFor jth
The amplitude factor of paths, δ (t- Δ ti) be the i-th paths shock response, Δ tiFor the time delay of the i-th paths, Δ tjIt is
The time delay of j paths, C (- t- Δ ti) meaning be time reversal the delayed time Δ t of cape signaliSignal afterwards, S (- t-
Δti) meaning be time reversal carrying information pulse or the delayed time Δ t of burst signaliSignal afterwards, C (- t)
For the cape signal of time reversal, S (- t) is pulse or the burst signal of the carrying information of time reversal, C (- t+ Δ ti-Δ
tj) be time reversal the delayed time Δ t of cape signalj-ΔtiSignal afterwards, S (- t+ Δ ti-Δtj) it is time reversal
Carry pulse or the delayed time Δ t of burst signal of informationj-ΔtiSignal afterwards, * are convolution symbol.
6. a kind of Information hiding formula radio transmitting method based on time reversal according to claim 1, which is characterized in that
In step (6)
Wherein, N is the quantity of multipath, aiFor the amplitude factor of the i-th paths, ajFor the amplitude factor in j-th strip path, Δ tiFor
The time delay of i-th paths, Δ tjFor the time delay in j-th strip path, C (t) is cape signal, and S (t) is pulse or burst signal, C
(t+Δti-Δtj) it is the delayed Δ t of cape signalj-ΔtiSignal after time, S (t+ Δ ti-Δtj) it is the arteries and veins for carrying information
Punching or the delayed Δ t of burst signalj-ΔtiSignal after time.
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106253939B (en) * | 2016-08-25 | 2018-10-16 | 电子科技大学 | One kind being based on co-channel full duplex electromagnetic communication method while time reversal |
| CN106712310B (en) * | 2017-03-10 | 2020-01-21 | 电子科技大学 | Distributed wireless energy transmission method based on time reversal |
| CN107911191B (en) * | 2017-11-06 | 2020-08-18 | 重庆邮电大学 | Information safety transmission method based on time reversal technology |
| CN109660553A (en) * | 2019-01-07 | 2019-04-19 | 重庆邮电大学 | Downlink safe transmission strategy based on time reversal technology |
| CN110120711B (en) * | 2019-04-17 | 2022-05-03 | 电子科技大学 | Autonomous dynamic wireless power receiving device and method based on time reversal |
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| CN101867921A (en) * | 2010-06-11 | 2010-10-20 | 电子科技大学 | Communication method capable of improving hiding performance of wireless sensor network |
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