CN115189993B - TDCS basic modulation waveform design method, device and information transmitting and receiving method - Google Patents
TDCS basic modulation waveform design method, device and information transmitting and receiving method Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/36—Modulator circuits; Transmitter circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/382—Monitoring; Testing of propagation channels for resource allocation, admission control or handover
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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
- H04L25/0202—Channel estimation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords
- H04L9/0875—Generation of secret information including derivation or calculation of cryptographic keys or passwords based on channel impulse response [CIR]
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
The invention discloses a TDCS basic modulation waveform design method, a device and an information transmitting and receiving method, which comprise the following steps: carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier; according to the estimated value corresponding to each subcarrier, an amplitude matrix I H and a phase matrix theta are obtained; generating an amplitude spectrum shaping vector A by utilizing spectrum sensing of a spectrum environment where a TDCS is positioned, an amplitude matrix |H| and a preset subcarrier selection threshold; and performing dot multiplication on the random phase sequence P, the amplitude spectrum shaping vector A and the conjugate of the phase matrix theta which are obtained by mapping, and generating a basic modulation waveform B in a frequency domain form through energy adjustment. The waveform design method provided by the invention improves the effective utilization of the system to the transmitting power; meanwhile, the risk that the basic modulation waveform is intercepted and cracked is reduced, and the safety of a transmission system is improved.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a method and apparatus for designing a TDCS basic modulation waveform, and a method for transmitting and receiving information.
Background
The TDCS (Transform Domain Communication System ) can adaptively select idle subcarriers to generate basic modulation waveforms through sensing surrounding electromagnetic environments, so that the purposes of avoiding interference and improving the frequency spectrum utilization rate are achieved. And as a spread spectrum technology, the basic modulation waveform of the TDCS also has the characteristics of low detection and low interception, and has wide application prospect in the fields of secret communication and military communication.
The generation and transmission of the basic modulation waveform in the conventional TDCS is as shown in fig. 1. The TDCS utilizes a subcarrier selection threshold mu set in advance to select available subcarriers to finish amplitude spectrum forming through sensing the frequency spectrum, specifically, when the interference power sum in the subcarriers is more than or equal to mu, the amplitude spectrum of the subcarriers is set to be 0; otherwise, set to 1. I.e.
Wherein N represents the number of subcarriers, A k Representing the magnitude spectrum value formed on the kth subcarrier,power representing environmental interference on kth subcarrier, a= [ a ] 0 ,A 1 ,…,A N-1 ]Representing the generated magnitude spectrum. Then, the generated amplitude spectrum A is multiplied by a random phase sequence P, and the obtained signal is subjected to energy adjustment to obtain a frequency domain form of a basic modulation waveform, wherein the mapping process of the random phase sequence is shown in fig. 2.
The random phase sequence is first generated by an n-order linear feedback register (LFSR) with a period of 2 n -1, then randomly selecting r sequentially generated m from n shift registers k And thus mapped into a random phase sequence P. The energy adjustment mainly ensures that the total power of the emission is unchanged, and the adjustment factor thereof Wherein ε is s Representing the energy required to transmit a symbol, N A Representing amplitudeNumber of 1 in the spectrum. The frequency domain representation of the generated waveform at this time is
Obtaining the time domain representation of the basic modulation waveform through inverse Fourier transform (IFFT)
The information to be transmitted is modulated onto the basic modulation waveform by circumference shift keying (CCSK) and transmitted through the transmitting antenna. The receiving end firstly carries out channel equalization on the received signal by utilizing the frequency domain channel state information of the channel estimation; then, generating the same basic modulation waveform (only considering the situation of frequency spectrum perception matching at the receiving and transmitting ends) with the transmitting end through the same frequency spectrum perception, amplitude spectrum shaping and random phase mapping process with the transmitting end; finally, the detection of the signals is completed through CCSK coherent demodulation. The process flow is shown in fig. 3.
The above prior art has the following problems: because the energy of the transmitted signal can be injected into some channels with larger transmission fading, the transmitted energy can not be converted into the transmission rate, and the utilization rate of the transmitted energy is reduced; the confidentiality of the system is not high, and the basic modulation waveform generated by adopting the same pseudo-random sequence for a long time is easy to intercept and crack by a monitoring party, so that the risk of cracking information is increased.
Disclosure of Invention
The invention provides a TDCS basic modulation waveform design method, a device and an information transmitting and receiving method aiming at the problems.
The method for designing the TDCS basic modulation waveform provided by the invention comprises the following steps:
carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier;
according to the estimated value corresponding to each subcarrier, an amplitude matrix I H and a phase matrix theta are obtained;
generating an amplitude spectrum shaping vector A by utilizing spectrum sensing of a spectrum environment where a TDCS is positioned, an amplitude matrix |H| and a preset subcarrier selection threshold;
and performing dot multiplication on the random phase sequence P, the amplitude spectrum shaping vector A and the conjugate of the phase matrix theta which are obtained by mapping, and generating a basic modulation waveform B in a frequency domain form through energy adjustment.
Further, the estimated value corresponding to the kth subcarrier channel state informationThe amplitude matrix |H| and the phase matrix theta are as follows according to the estimated values corresponding to the subcarriers:
amplitude matrix |h|= [ |h 0 |,|H 1 |,…,|H N-1 |]；
Phase matrix
Wherein, |H k I and theta k The amplitude and phase of the frequency domain channel state information on the kth subcarrier are respectively represented, k=0, 1, …, and N-1, N is the number of subcarriers.
Further, the spectrum sensing of the spectrum environment where the TDCS is located, the amplitude matrix |h| and the preset subcarrier selection threshold are utilized to generate an amplitude spectrum shaping vector a as follows:
according to the formulaObtaining amplitude spectrum values formed on each subcarrier, wherein A k Is the amplitude spectrum value formed on the kth subcarrier;
according to the amplitude spectrum value formed on each subcarrier, an amplitude spectrum shaping vector is obtained, wherein the amplitude spectrum shaping vector A= [ A ] 0 ,A 1 ,…,A N-1 ]。
Further, the generated frequency domain form of the basic modulation waveform is:
wherein lambda is the adjustment factor and,ε s representing the energy required to transmit a symbol, N A The number of subcarriers having a magnitude spectrum value of 1 is indicated.
The invention also provides an information transmitting method, which comprises the following steps:
modulating information to be transmitted onto a basic modulation waveform through CCSK, and transmitting the basic modulation waveform through a transmitting antenna, wherein the basic modulation waveform is a pre-stored basic modulation waveform b in a time domain form;
the basic modulation waveform B in the time domain form is obtained by performing inverse Fourier transform on the basic modulation waveform B in the frequency domain form;
the basic modulation waveform B in the frequency domain form is a basic modulation waveform in the frequency domain form obtained according to the TDCS basic modulation waveform design method described above.
The invention also provides an information receiving method, which comprises the following steps:
obtaining an amplitude spectrum shaping vector A according to spectrum sensing and channel estimation;
performing random phase mapping to obtain a random phase sequence P;
performing conjugate operation after performing dot multiplication on the amplitude spectrum shaping vector A and the random phase sequence P;
and performing Fourier transformation on the received signal, performing dot multiplication on a conjugate operation result, and then sequentially performing inverse Fourier transformation, real part taking and CCSK coherent demodulation, wherein the received signal is a signal transmitted from a transmitter according to the information transmitting method.
The invention also provides a TDCS basic modulation waveform design device, which comprises a channel estimation module, an amplitude phase matrix acquisition module, an amplitude spectrum shaping vector acquisition module and a basic modulation waveform generation module, wherein:
the channel estimation module is connected with the amplitude phase matrix acquisition module and is used for carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier;
the amplitude phase matrix acquisition module is respectively connected with the amplitude spectrum shaping vector acquisition module and the basic modulation waveform generation module and is used for acquiring an amplitude matrix I H and a phase matrix theta according to the estimated values corresponding to the subcarriers;
the amplitude spectrum shaping vector acquisition module is connected with the basic modulation waveform generation module and is used for generating an amplitude spectrum shaping vector A by utilizing spectrum sensing of a spectrum environment where the TDCS is positioned, an amplitude matrix |H| and a preset subcarrier selection threshold;
the basic modulation waveform generation module is used for performing dot multiplication on the random phase sequence P, the amplitude spectrum shaping vector A and the conjugate of the phase matrix theta which are obtained by mapping, and generating a basic modulation waveform B in a frequency domain form through energy adjustment.
Further, the estimated value corresponding to the kth subcarrier channel state informationThe amplitude phase matrix acquisition module comprises a receiving unit, an amplitude matrix acquisition unit and a phase matrix acquisition unit, wherein:
the receiving unit is respectively connected with the amplitude matrix acquisition unit and the phase matrix acquisition unit and is used for receiving the estimated values corresponding to the subcarriers;
the amplitude matrix obtaining unit is used for obtaining the estimated value corresponding to each subcarrier and the formula: amplitude matrix |h|= [ |h 0 |,|H 1 |,…,|H N-1 |]Obtaining an amplitude matrix |H|;
the phase matrix acquisition unit is used for acquiring the estimated value and the formula corresponding to each subcarrier: phase matrixObtaining a phase matrix theta;
wherein, |H k I and theta k Respectively representing the amplitude and phase of the frequency domain channel state information on the kth subcarrier, k=0, 1, …N-1, N is the number of subcarriers.
Further, the amplitude spectrum shaping vector acquisition module comprises an amplitude spectrum value acquisition unit and an amplitude spectrum shaping vector acquisition unit, wherein:
the amplitude spectrum value acquisition unit is connected with the amplitude spectrum shaping vector acquisition unit and is used for acquiring the amplitude spectrum shaping vector according to the formulaObtaining amplitude spectrum values formed on each subcarrier, wherein A k For amplitude spectrum value A formed on kth subcarrier k ；
An amplitude spectrum shaping vector obtaining unit, configured to obtain an amplitude spectrum shaping vector according to the amplitude spectrum values formed on each subcarrier, where the amplitude spectrum shaping vector a= [ a ] 0 ,A 1 ,…,A N-1 ]。
Further, the frequency domain form of the basic modulation waveform generated by the basic modulation waveform generating module is:
wherein lambda is the adjustment factor and,ε s representing the energy required to transmit a symbol, N A The number of subcarriers having a magnitude spectrum value of 1 is indicated.
The method and the device for designing the TDCS basic modulation waveform and the method for transmitting and receiving the information provided by the invention at least comprise the following beneficial effects:
(1) The frequency spectrum sensing and the frequency domain channel state information are utilized to screen the subcarriers, so that the influence of environmental interference and channels on transmission performance can be comprehensively considered, the subcarriers with stronger interference are removed, and the subcarriers with poor channel states are removed, so that the reliability of system transmission is improved, and meanwhile, the effective utilization of the system on the transmitting power is improved;
(2) By utilizing the uncertainty and the characteristic of the slowly-varying characteristic of the frequency domain channel state information (specifically, the channel phase uncertainty is utilized to realize the 'one-time-pad' processing of the basic modulation waveform), the generated basic modulation waveform has the random phase mapping of the 'one-time-pad', thereby reducing the risk of interception and cracking of the basic modulation waveform and improving the safety of a transmission system.
Drawings
For a clearer description of embodiments of the invention or of solutions in the prior art, the drawings which are used in the description of the embodiments or of the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a TDCS transmitter in the prior art;
FIG. 2 is a schematic diagram of a prior art random phase sequence mapping process;
fig. 3 is a block diagram of a TDCS receiver in the prior art;
FIG. 4 is a flowchart of a method for designing a TDCS basic modulation waveform in an embodiment of the present invention;
fig. 5 is a block diagram of a TDCS transmitter in one embodiment of the invention;
fig. 6 is a block diagram of a TDCS receiver in one embodiment of the invention;
fig. 7 is a schematic structural diagram of a TDCS basic modulation waveform design apparatus according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of an amplitude-phase matrix acquisition module according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of an amplitude spectrum shaping vector acquisition module according to an embodiment of the present invention;
FIG. 10 is a flow chart of a frequency domain transformation method;
FIG. 11 is a time domain diagram of a basic modulation waveform generated by the present invention and the prior art;
FIG. 12 is a schematic representation of the autocorrelation of the present invention to produce a basic modulation waveform, the cross-correlation of the present invention with the prior art to produce a basic modulation waveform;
FIG. 13 is a diagram showing the bit error rate comparison between the present invention and the prior art under different CCSK modulation;
701-channel estimation module, 702-amplitude phase matrix acquisition module, 703-amplitude spectrum shaping vector acquisition module, 704-basic modulation waveform generation module, 7021-receiving unit, 7022-amplitude matrix acquisition unit, 7023-phase matrix acquisition unit, 7031-amplitude spectrum value acquisition unit, 7032-amplitude spectrum shaping vector acquisition unit.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
In one embodiment of the present invention, as shown in fig. 4 and 5, the present invention provides a method for designing a TDCS basic modulation waveform, specifically, a method for designing a waveform of a transform domain communication system based on environment and transmission awareness. The method comprises the following steps:
step S101: carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier;
step S102: according to the estimated value corresponding to each subcarrier, an amplitude matrix I H and a phase matrix theta are obtained;
specifically, if the estimated value corresponding to the kth subcarrier channel state informationThe amplitude matrix |h| and the phase matrix θ are in this step according to the estimated values corresponding to the respective subcarriers:
amplitude matrix |h|= [ |h 0 |,|H 1 |,…,|H N-1 |]；
Phase matrix
Wherein, |H k I and theta k The amplitude and phase of the frequency domain channel state information on the kth subcarrier are respectively represented, k=0, 1, …, and N-1, N is the number of subcarriers.
Step S103: generating an amplitude spectrum shaping vector A by utilizing spectrum sensing of a spectrum environment where a TDCS is positioned, an amplitude matrix |H| and a preset subcarrier selection threshold;
specifically, in one implementation, the generating the magnitude spectrum shaping vector a by using the spectrum sensing of the spectrum environment where the TDCS is located, the magnitude matrix |h| and the preset subcarrier selection threshold includes the following steps:
step S1031: according to the formulaObtaining amplitude spectrum values formed on each subcarrier, wherein A k Is the amplitude spectrum value formed on the kth subcarrier;
represents the power of interference on the kth subcarrier, μ T And selecting a threshold for the preset subcarriers.
Further, since the coefficient of the received signal after the equalizer is ρ is
Therefore, the ratio of the electromagnetic environment interference power to the frequency domain channel state information power is utilizedTo make subcarrier selection.
Step S1032: according to the amplitude spectrum value formed on each subcarrier, an amplitude spectrum shaping vector is obtained, wherein the amplitude spectrum shaping vector A= [ A ] 0 ,A 1 ,…,A N-1 ]。
Step S104: and performing dot multiplication on the random phase sequence P, the amplitude spectrum shaping vector A and the conjugate of the phase matrix theta which are obtained by mapping, and generating a basic modulation waveform B in a frequency domain form through energy adjustment.
Specifically, in this step, the frequency domain form of the generated basic modulation waveform is:
wherein lambda is the adjustment factor and,ε s representing the energy required to transmit a symbol, N A Representing the number of subcarriers with a magnitude spectrum value of 1, < >>Representing the conjugate of the phase matrix θ.
Compared with the traditional TDCS, the TDCS basic modulation waveform design method provided by the invention has the advantages that the step of channel estimation is added at the transmitting end, the estimated frequency domain channel state information is decomposed into two parts of amplitude |H| and phase θ, the amplitude |H| is sent to an amplitude spectrum forming module for judging whether subcarriers are available or not, the conjugation of the phase θ is directly subjected to dot multiplication with the generated random phase P and amplitude spectrum forming vector A, and the frequency domain representation form of the basic modulation waveform is generated after energy adjustment.
The invention provides a TDCS basic modulation waveform design method, which comprises the steps of firstly carrying out channel estimation on frequency domain channel state information on each subcarrier to obtain estimation values corresponding to each subcarrier, and then generating an amplitude spectrum shaping vector A by utilizing spectrum sensing of a spectrum environment where the TDCS is positioned, the amplitude matrix I H and a preset subcarrier selection threshold when generating the amplitude spectrum shaping vector according to an amplitude matrix I H and a phase matrix theta by selecting the subcarriers; the subcarrier is screened by utilizing frequency spectrum sensing and frequency domain channel state information, so that the influence of environmental interference and a channel on transmission performance can be comprehensively considered, and the effective utilization of the system on the transmitting power, namely the transmitting energy utilization rate, is improved.
In addition, the method for designing the TDCS basic modulation waveform is realized by performing dot multiplication on the random phase sequence P, the amplitude spectrum shaping vector A and the conjugate of the phase matrix theta which are obtained by mapping when the basic modulation waveform in a frequency domain form is generated, and the generated basic modulation waveform has random phase mapping of one-time-density by utilizing the uncertainty and the slowly-varying characteristic of the channel state information of the frequency domain (particularly realizing the one-time-density processing of the basic modulation waveform by utilizing the uncertainty of the channel phase), so that the risk of interception and cracking of the basic modulation waveform is reduced, the safety of a transmission system is improved, and meanwhile, the generated waveform also has the noise-like characteristics of strong autocorrelation and weak cross correlation.
In still another embodiment of the present invention, the present invention further provides an information transmitting method, as shown in fig. 5, where the method includes:
modulating information to be transmitted onto a basic modulation waveform through CCSK, and transmitting the basic modulation waveform through a transmitting antenna, wherein the basic modulation waveform is a pre-stored basic modulation waveform b in a time domain form;
the basic modulation waveform B in the time domain form is obtained by performing inverse Fourier transform on the basic modulation waveform B in the frequency domain form;
the basic modulation waveform B in the frequency domain form is a basic modulation waveform in the frequency domain form obtained according to the TDCS basic modulation waveform design method described above.
In still another embodiment of the present invention, the present invention further provides an information receiving method, as shown in fig. 6, including:
obtaining an amplitude spectrum shaping vector A according to spectrum sensing and channel estimation;
performing random phase mapping to obtain a random phase sequence P;
performing conjugate operation after performing dot multiplication on the amplitude spectrum shaping vector A and the random phase sequence P;
and performing Fourier transformation on the received signal, performing dot multiplication on a conjugate operation result, and then sequentially performing inverse Fourier transformation, real part taking and CCSK coherent demodulation, wherein the received signal is a signal transmitted from a transmitter according to the information transmitting method.
Specifically, due to reciprocity of uplink and downlink channels, the transmitting end and the receiving end can obtain the same channel estimation.
With reference to fig. 3 and fig. 6, the information receiving method at the receiving end provided by the invention is different from the traditional TDCS in that an equalization module is omitted and equalization is not required; in addition, when the information receiving method provided by the invention is used for shaping the amplitude spectrum, the environment interference power and the channel state information power are comprehensively utilized (the specific amplitude spectrum shaping process is consistent with that in the step S103, and redundant description is omitted here).
More specifically, at the receiving end, a random phase mapping is performed, and a specific implementation method for obtaining the random phase sequence P is the same as a mapping method in a traditional TDCS, which is not limited in the present invention.
As can be seen from the figure, the receiver in the scheme can omit an equalization module, and only uses the estimated channel state information to complete the shaping of the amplitude spectrum, thereby simplifying the implementation complexity of the receiver.
The invention also provides a TDCS basic modulation waveform design device, as shown in fig. 7, which includes a channel estimation module 701, an amplitude phase matrix acquisition module 702, an amplitude spectrum shaping vector acquisition module 703, and a basic modulation waveform generation module 704, wherein:
the channel estimation module 701 is connected to the amplitude phase matrix acquisition module 702, and is configured to perform channel estimation on the frequency domain channel state information on each subcarrier, so as to obtain an estimated value corresponding to each subcarrier;
the amplitude phase matrix acquisition module 702 is respectively connected with the amplitude spectrum shaping vector acquisition module 703 and the basic modulation waveform generation module 704, and is used for acquiring an amplitude matrix |H and a phase matrix theta according to the estimation values corresponding to the subcarriers;
the amplitude spectrum shaping vector acquisition module 703 is connected with the basic modulation waveform generation module 704, and is configured to generate an amplitude spectrum shaping vector a by using spectrum sensing of a spectrum environment where the TDCS is located, an amplitude matrix |h| and a preset subcarrier selection threshold;
the basic modulation waveform generating module 704 is configured to perform dot multiplication on the mapped random phase sequence P, the amplitude spectrum shaping vector a, and the conjugate of the phase matrix θ, and generate a basic modulation waveform B in a frequency domain form through energy adjustment.
Further, the estimated value corresponding to the kth subcarrier channel state informationAs shown in fig. 8, the amplitude-phase matrix acquisition module 702 includes a reception unit 7021, an amplitude matrix acquisition unit 7022, and a phase matrix acquisition unit 7023, in which:
a receiving unit 7021, connected to the amplitude matrix acquiring unit 7022 and the phase matrix acquiring unit 7023, respectively, for receiving the estimated values corresponding to the subcarriers;
an amplitude matrix acquiring unit 7022, configured to obtain an estimated value corresponding to each subcarrier and a formula amplitude matrix |h|= [ |h 0 |,|H 1 |,…,|H N-1 |]Obtaining an amplitude matrix |H|;
a phase matrix acquiring unit 7023 for acquiring a formula phase matrix according to the estimation value corresponding to each subcarrierObtaining a phase matrix theta;
wherein, |H k I and theta k The amplitude and phase of the frequency domain channel state information on the kth subcarrier are respectively represented, k=0, 1, …, and N-1, N is the total number of subcarriers.
Further, as shown in fig. 9, the amplitude spectrum shaping vector acquisition module 703 includes an amplitude spectrum value acquisition unit 7031 and an amplitude spectrum shaping vector acquisition unit 7032, in which:
an amplitude spectrum value acquiring unit 7031 connected with the amplitude spectrum shaping vector acquiring unit 7032 for acquiring the amplitude spectrum shaping vector according to the formulaObtaining amplitude spectrum values formed on each subcarrier, wherein A k For amplitude spectrum value A formed on kth subcarrier k ；
A magnitude spectrum shaping vector obtaining unit 7032, configured to obtain a magnitude spectrum shaping vector according to magnitude spectrum values formed on each subcarrier, where the magnitude spectrum shaping vector a= [ a ] 0 ,A 1 ,…,A N-1 ]。
Further, in yet another embodiment of the present invention, the frequency domain form of the basic modulation waveform generated by the basic modulation waveform generating module 704 is:
wherein lambda is the adjustment factor and,ε s representing the energy required to transmit a symbol, N A The number of subcarriers having a magnitude spectrum value of 1 is indicated.
The system performance simulation is carried out aiming at the TDCS basic modulation waveform design method provided by the invention:
1. simulation conditions
In the simulation, a frequency domain transformation method is adopted to generate a channel, and an implementation block diagram is shown in fig. 10, wherein the frequency domain response S (f) of the spectrum shaping filter is as follows:
table 1 simulation parameter settings
2. Simulation results
The simulation results are shown in fig. 11, 12 and 13, wherein fig. 11 compares the time domain basic modulation waveform generated by the conventional TDCS scheme with the time domain basic modulation waveform generated by the present invention, and it can be seen that the time domain basic modulation waveform generated by the present invention has noise-like characteristics as the conventional scheme. Fig. 12 simulates the autocorrelation characteristics of the generated time-domain basic modulation waveform and the cross-correlation characteristics of the generated time-domain basic modulation waveform with the conventional scheme, and shows that the generated waveform has the characteristics of strong autocorrelation and weak cross-correlation, and meanwhile, even if an illegal user intercepts the generation strategy of the conventional scheme basic modulation waveform, the basic modulation waveform with strong autocorrelation with a legal user cannot be generated due to different transmission channels, so that the transmission safety of the invention is reflected compared with the conventional scheme. In fig. 13, the technical solution proposed by the present invention is simulated for CCSK with different modulation orders, and the conventional solution adopts a Minimum Mean Square Error (MMSE) algorithm to perform frequency domain equalization.
The terms and expressions used in the description of the present invention are used as examples only and are not meant to be limiting. It will be appreciated by those skilled in the art that numerous changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosed embodiments. The scope of the invention is, therefore, to be determined only by the following claims, in which all terms are to be understood in their broadest reasonable sense unless otherwise indicated.
Claims (8)
1. A method for designing a TDCS basic modulation waveform, the method comprising:
carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier;
amplitude matrix according to estimation value corresponding to each subcarrierAnd phase matrix->；
Spectrum sensing and amplitude matrix using spectrum environment where TDCS is locatedAnd a preset subcarrier selection threshold, generating a magnitude spectrum shaping vector ++>；
Mapping the obtained random phase sequenceAmplitude spectrum shaping vector->Phase matrix->Is subjected to dot multiplication and energy adjustment to generate a basic modulation waveform in a frequency domain form +.>；
Wherein, the estimation value corresponding to the kth subcarrier channel state information
；
Amplitude matrix according to estimation value corresponding to each subcarrierAnd phase matrix->The method comprises the following steps:
amplitude matrix；
Phase matrix；
Wherein,and->The amplitude and phase of the frequency domain channel state information on the kth subcarrier are represented respectively,n is the number of subcarriers.
2. The method for designing a TDCS basic modulation waveform according to claim 1, wherein the TDCS basic modulation waveform is characterized by using a spectrum sensing and amplitude matrix of a spectrum environment in which the TDCS is locatedAnd a preset subcarrier selection threshold, generating a magnitude spectrum shaping vector ++>The method comprises the following steps: according to the formula->The method comprises the steps of carrying out a first treatment on the surface of the Obtaining amplitude spectrum values formed on each subcarrier, wherein +.>Is the amplitude spectrum value formed on the kth subcarrier;
obtaining an amplitude spectrum shaping vector according to the amplitude spectrum values formed on each subcarrier, wherein the amplitude spectrum shaping vector。
3. The TDCS basic modulation waveform design method according to claim 2, wherein the frequency domain form of the generated basic modulation waveform is:
；
wherein the method comprises the steps ofFor adjusting the factor->Represents the energy required to transmit a symbol, < >>The number of subcarriers having a magnitude spectrum value of 1 is indicated.
4. An information transmission method, the method comprising:
modulating information to be transmitted onto a basic modulation waveform through CCSK, and transmitting the basic modulation waveform through a transmitting antenna, wherein the basic modulation waveform is a basic modulation waveform b in a pre-stored time domain form;
the basic modulation waveform b in the time domain form is a basic modulation waveform for the frequency domain formPerforming inverse Fourier transform to obtain;
the basic modulation waveform in the frequency domainA basic modulation waveform in a frequency domain form obtained for the TDCS basic modulation waveform designing method according to any one of claims 1 to 3.
5. An information receiving method, the method comprising:
obtaining an amplitude spectrum shaping vector according to spectrum sensing and channel estimation；
Performing random phase mapping to obtain a random phase sequence；
Shaping the amplitude spectrum into vectorsAnd random phase sequence->Performing conjugate operation after dot multiplication;
after performing fourier transformation and dot multiplication on a conjugate operation result on a received signal, performing inverse fourier transformation, taking a real part and CCSK coherent demodulation in sequence, wherein the received signal is a signal transmitted from a transmitter according to the information transmission method of claim 4.
6. The device is characterized by comprising a channel estimation module, an amplitude phase matrix acquisition module, an amplitude spectrum shaping vector acquisition module and a basic modulation waveform generation module, wherein:
the channel estimation module is connected with the amplitude phase matrix acquisition module and is used for carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimated value corresponding to each subcarrier;
the amplitude phase matrix acquisition module is respectively connected with the amplitude spectrum shaping vector acquisition module and the basic modulation waveform generation module and is used for acquiring an amplitude matrix according to the estimation values corresponding to all the subcarriersAnd phase matrix->；
The amplitude spectrum shaping vector acquisition module is connected with the basic modulation waveform generation module and is used for utilizing spectrum sensing and amplitude matrix of the spectrum environment where the TDCS is positionedAnd a preset subcarrier selection threshold, generating a magnitude spectrum shaping vector ++>；
The basic modulation waveform generation module is used for mapping the obtained random phase sequenceAmplitude spectrum shaping vector->Phase matrix->Is subjected to dot multiplication and energy adjustment to generate a basic modulation waveform in a frequency domain form +.>；
Wherein, the estimation value corresponding to the kth subcarrier channel state information
The method comprises the steps of carrying out a first treatment on the surface of the The amplitude phase matrix acquisition module comprises a receiving unit, an amplitude matrix acquisition unit and a phase matrix acquisition unit, wherein:
the receiving unit is respectively connected with the amplitude matrix acquisition unit and the phase matrix acquisition unit and is used for receiving the estimated values corresponding to all the subcarriers;
the amplitude matrix obtaining unit is configured to obtain, according to the estimated values corresponding to each subcarrier and the formula: amplitude matrixObtaining an amplitude matrix->；
The phase matrix obtaining unit is configured to obtain, according to the estimated values corresponding to each subcarrier and the formula: phase matrixObtaining a phase matrix->；
Wherein,and->Respectively representing the amplitude and phase of the frequency domain channel state information on the kth subcarrier,/for each subcarrier>N is the number of subcarriers.
7. The TDCS basic modulation waveform design apparatus according to claim 6, wherein the amplitude spectrum shaping vector acquisition module includes an amplitude spectrum value acquisition unit and an amplitude spectrum shaping vector acquisition unit, wherein:
the amplitude spectrum value acquisition unit is connected with the amplitude spectrum shaping vector acquisition unit and is used for acquiring the amplitude spectrum shaping vector according to the formula
The method comprises the steps of carrying out a first treatment on the surface of the Obtaining amplitude spectrum values formed on each subcarrier, wherein +.>For the amplitude spectrum value formed on the kth subcarrier +.>；
The amplitude spectrum shaping vector obtaining unit is configured to obtain an amplitude spectrum shaping vector according to the amplitude spectrum values formed on each subcarrier, where the amplitude spectrum shaping vector。
8. The TDCS basic modulation waveform design apparatus of claim 6, wherein the frequency domain form of the basic modulation waveform generated by the basic modulation waveform generation module is:
；
wherein the method comprises the steps ofFor adjusting the factor->Represents the energy required to transmit a symbol, < >>The number of subcarriers having a magnitude spectrum value of 1 is indicated.
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