CN115189993A - TDCS basic modulation waveform design method and device and information transmitting and receiving method - Google Patents
TDCS basic modulation waveform design method and device and information transmitting and receiving method Download PDFInfo
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- H—ELECTRICITY
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- 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
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- H—ELECTRICITY
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- 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
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- 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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- 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
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a TDCS basic modulation waveform design method, a TDCS basic modulation waveform design device and an information transmitting and receiving method, wherein the TDCS basic modulation waveform design method comprises the following steps: performing channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier; obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier; generating a magnitude spectrum forming vector A by using spectrum sensing of a frequency spectrum environment where the TDCS is located, a magnitude matrix | H | and a preset subcarrier selection threshold; and performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and performing energy adjustment to generate a basic modulation waveform B in a frequency domain form. The waveform design method provided by the invention improves the effective utilization of the system to the transmitting power; meanwhile, the risk of interception and decryption of the basic modulation waveform 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 an 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 an idle subcarrier to generate a basic modulation waveform by sensing a surrounding electromagnetic environment, thereby achieving the purpose of avoiding interference and improving the spectrum utilization rate. In addition, 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 shown in fig. 1. The TDCS selects available subcarriers to complete amplitude spectrum forming by sensing the frequency spectrum and utilizing a preset subcarrier selection threshold mu, and particularly, when the sum of interference power in the subcarriers is more than or equal to mu, the amplitude spectrum of the subcarriers is set to be 0; otherwise, it is set to 1. Namely, it is
Wherein N represents the number of subcarriers, A k Representing the amplitude spectrum value formed on the k-th subcarrier,
represents the power of the environmental interference on the k-th subcarrier, a = [ a = 0 ,A 1 ,…,A N-1 ]Representing the generated amplitude spectrum. Then, the generated amplitude spectrum A is multiplied by the random phase sequence P to obtain a signalThe modulated energy is then the frequency domain form of the 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 from n shift registers to generate m k And then mapped into a random phase sequence P. The energy regulation mainly ensures that the total power emitted is constant, and the regulation factor is
Wherein epsilon s Representing the energy required to transmit a symbol, N A Indicates the number of 1 s in the amplitude spectrum. The frequency domain representation of the waveform generated at this time is
After inverse Fourier transform (IFFT), a time domain representation of the basic modulation waveform is obtained
The information to be transmitted is modulated onto the basic modulation waveform by the circular shift keying (CCSK) and transmitted by the transmitting antenna. The receiving end firstly utilizes the frequency domain channel state information of the channel estimation to carry out channel equalization on the received signal; next, generating a basic modulation waveform which is the same as the transmitting end through the same spectrum sensing, amplitude spectrum shaping and random phase mapping processes as the transmitting end (only the condition that the spectrum sensing at the transmitting end and the receiving end are matched is considered); and finally, the signal detection is completed through CCSK coherent demodulation. The processing 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 large 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 basic modulation waveforms generated by adopting the same pseudorandom sequence for a long time are easy to intercept and crack by a monitored party, so that the risk of cracking information is increased.
Disclosure of Invention
In view of the above problems, the present invention provides a TDCS basic modulation waveform design method, apparatus and information transmitting and receiving method.
The TDCS basic modulation waveform design method provided by the invention comprises the following steps:
performing channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier;
generating a magnitude spectrum forming vector A by using the spectrum sensing of the frequency spectrum environment where the TDCS is located, the magnitude matrix | H | and a preset subcarrier selection threshold;
and performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and performing energy adjustment to generate a basic modulation waveform B in a frequency domain form.
Further, the estimated value corresponding to the k sub-carrier channel state information
Obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier, wherein the amplitude matrix | H | and the phase matrix theta are as follows:
amplitude matrix | H | = [ | H 0 |,|H 1 |,…,|H N-1 |]；
Phase matrix
Wherein, | H k I and theta k Respectively representing the amplitude and phase of the frequency domain channel state information on the k-th subcarrier, k =0,1, \ 8230, N-1, N being the number of subcarriers.
Further, by using spectrum sensing, amplitude matrix | H | and a preset subcarrier selection threshold of a spectrum environment in which the TDCS is located, a magnitude spectrum shaping vector a is generated as follows:
according to the formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k The amplitude spectrum value formed on the k sub-carrier;
obtaining a magnitude spectrum forming vector according to the magnitude spectrum value formed on each subcarrier, wherein the magnitude spectrum forming vector A = [ A = [ A ] 0 ,A 1 ,…,A N-1 ]。
Further, the frequency domain form of the generated basic modulation waveform is:
wherein the lambda is a regulation factor, and the lambda is,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1.
The invention also provides an information transmitting method, which comprises the following steps:
modulating information to be transmitted to a basic modulation waveform through the CCSK, and transmitting the information 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 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 the 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 a magnitude spectrum forming vector A according to frequency spectrum sensing and channel estimation;
random phase mapping is carried out to obtain a random phase sequence P;
performing point multiplication on the amplitude spectrum forming vector A and the random phase sequence P, and then performing conjugate operation;
after Fourier transform is carried out on the received signal, point multiplication is carried out on the received signal and the result of conjugate operation, inverse Fourier transform, a real part and CCSK coherent demodulation are carried out in sequence, wherein the received signal is the signal transmitted from the transmitter according to the information transmission 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 forming 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 used for carrying out channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
the amplitude phase matrix acquisition module is respectively connected with the amplitude spectrum forming vector acquisition module and the basic modulation waveform generation module and is used for obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier;
the amplitude spectrum forming vector acquisition module is connected with the basic modulation waveform generation module and is used for generating an amplitude spectrum forming vector A by utilizing the frequency spectrum sensing, the amplitude matrix | H | and a preset subcarrier selection threshold of the frequency spectrum environment where the TDCS is located;
and the basic modulation waveform generation module is used for performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and generating a basic modulation waveform B in a frequency domain form through energy adjustment.
Further, the estimated value corresponding to the k sub-carrier channel state information
The amplitude and 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 acquiring unit and the phase matrix acquiring unit and is used for receiving the estimation value corresponding to each subcarrier;
an amplitude matrix obtaining unit, configured to: amplitude matrix | H | = [ | H 0 |,|H 1 |,…,|H N-1 |]Obtaining an amplitude matrix | H |;
a phase matrix obtaining unit, configured to obtain, according to the estimation value corresponding to each subcarrier and a formula: phase matrix
Obtaining 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 k-th subcarrier, k =0,1, \ 8230, N-1, N being the number of subcarriers.
Further, the magnitude spectrum forming vector obtaining module comprises a magnitude spectrum value obtaining unit and a magnitude spectrum forming vector obtaining unit, wherein:
an amplitude spectrum value obtaining unit connected with the amplitude spectrum forming vector obtaining unit and used for obtaining the amplitude spectrum value according to a formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k For the amplitude spectrum value A formed on the k sub-carrier k ；
A magnitude spectrum forming vector obtaining unit, configured to obtain a magnitude spectrum forming vector according to a magnitude spectrum value formed on each subcarrier, where a magnitude spectrum forming 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 generation module is:
wherein the lambda is an adjustment factor,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1.
The TDCS basic modulation waveform design method, the TDCS basic modulation waveform design device and the information transmitting and receiving method provided by the invention at least have the following beneficial effects:
(1) The frequency spectrum sensing and the frequency domain channel state information are utilized to screen the subcarriers, the influence of environmental interference and a channel on the transmission performance can be comprehensively considered, the subcarriers with strong interference are eliminated, and the subcarriers with poor channel state are eliminated, so that the transmission reliability of the system is improved, and meanwhile, the effective utilization of the transmission power by the system is improved;
(2) By using the characteristics of uncertainty and slow change of the state information of the frequency domain channel (particularly, by using the uncertainty of the channel phase to realize the 'one time pad' processing on the basic modulation waveform), the generated basic modulation waveform has random phase mapping of the 'one time pad', thereby reducing the risks of interception and decryption of the basic modulation waveform and improving the safety of a transmission system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a block diagram of a TDCS transmitter in the prior art;
FIG. 2 is a diagram illustrating a random phase sequence mapping process in the prior art;
fig. 3 is a block diagram of a TDCS receiver in the prior art;
FIG. 4 is a flow chart of a TDCS basic modulation waveform design method according to an embodiment of the present invention;
fig. 5 is a block diagram of a TDCS transmitter in an embodiment of the invention;
figure 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 structural diagram of a magnitude spectrum formed vector obtaining module in an embodiment of the present invention;
FIG. 10 is a schematic flow chart of a frequency domain transform 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 diagram of the autocorrelation of the basic modulation waveform generated by the present invention and the cross-correlation of the basic modulation waveform generated by the present invention and the prior art;
FIG. 13 is a schematic diagram comparing the bit error rate under different CCSK modulation according to the present invention and the prior art;
the device comprises a channel estimation module 701, an amplitude phase matrix acquisition module 702, an amplitude spectrum forming vector acquisition module 703, a basic modulation waveform generation module 704, a receiving unit 7021, an amplitude matrix acquisition unit 7022, a phase matrix acquisition unit 7023, an amplitude spectrum value acquisition unit 7031 and an amplitude spectrum forming vector acquisition unit 7032.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In an embodiment of the present invention, as shown in fig. 4 and 5, the present invention provides a TDCS basic modulation waveform design method, and in particular, a transform domain communication system waveform design method based on environment and transmission sensing. The method comprises the following steps:
step S101: performing channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
step S102: obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier;
specifically, if the estimated value corresponding to the k-th sub-carrier channel state information
Then, in this step, the amplitude matrix | H | and the phase matrix θ are obtained 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 Respectively representing the amplitude and phase of the frequency domain channel state information on the k-th subcarrier, k =0,1, \ 8230, and N-1, N is the number of subcarriers.
Step S103: generating a magnitude spectrum forming vector A by using the spectrum sensing of the frequency spectrum environment where the TDCS is located, the magnitude matrix | H | and a preset subcarrier selection threshold;
specifically, in an implementation manner, the generating of the magnitude spectrum shaping vector a by using the spectrum sensing of the spectrum environment in which the TDCS is located, the magnitude matrix | H | and the preset subcarrier selection threshold includes the following steps:
step S1031: according to the formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k The amplitude spectrum value formed on the k sub-carrier;
Furthermore, in Minimum Mean Square Error (MMSE) equalization, the coefficient of the received signal after passing through the equalizer is rho
Therefore, the ratio of the electromagnetic environment interference power to the frequency domain channel state information power is used
To perform subcarrier selection.
Step S1032: obtaining a magnitude spectrum forming vector according to the magnitude spectrum value formed on each subcarrier, wherein the magnitude spectrum forming vector A = [ A = [ A ] 0 ,A 1 ,…,A N-1 ]。
Step S104: and performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and performing energy adjustment to generate a basic modulation waveform B in a frequency domain form.
Specifically, in this step, the frequency domain form of the generated basic modulation waveform is:
wherein the lambda is an adjustment factor,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1,
representing the conjugate of the phase matrix theta.
Comparing fig. 1 and fig. 5, compared with the conventional TDCS, the TDCS basic modulation waveform design method provided by the present invention adds a step of channel estimation at the transmitting end, and decomposes the estimated frequency domain channel state information into two parts of amplitude | H | and phase θ, where the amplitude | H | is sent to an amplitude spectrum shaping module to determine whether a subcarrier is available, and the conjugate of the phase θ directly performs a dot multiplication with the generated random phase P and amplitude spectrum shaping vector a, and generates a frequency domain representation form of the basic modulation waveform after energy adjustment.
The TDCS basic modulation waveform design method provided by the invention comprises the steps of firstly carrying out channel estimation on frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier, then obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier, and then carrying out subcarrier selection to generate an amplitude spectrum forming vector, wherein the amplitude spectrum forming vector A is generated by utilizing the spectrum sensing of the frequency spectrum environment where the TDCS is located, the amplitude matrix | H | and a preset subcarrier selection threshold; the method screens the subcarriers by utilizing the frequency spectrum sensing and the frequency domain channel state information, can comprehensively consider the influence of environmental interference and a channel on the transmission performance, and is more favorable for improving the effective utilization of the system on the transmitting power, namely improving the utilization rate of the transmitting energy.
In addition, when generating the basic modulation waveform in the frequency domain form, the design method of the TDCS basic modulation waveform is realized by performing point multiplication on the random phase sequence P, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta which are obtained by mapping, and the generated basic modulation waveform has random phase mapping of 'one time pad' by utilizing the uncertainty and the slow-varying characteristic of the state information of a frequency domain channel (specifically, the 'one time pad' processing of the basic modulation waveform is realized 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 noise-like characteristics of strong autocorrelation and weak cross correlation.
In another embodiment of the present invention, the present invention further provides an information transmitting method, as shown in fig. 5, the method including:
modulating information to be transmitted to a basic modulation waveform through the CCSK, and transmitting the information 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 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 the basic modulation waveform in the frequency domain form obtained according to the TDCS basic modulation waveform design method described above.
In another embodiment of the present invention, the present invention further provides an information receiving method, as shown in fig. 6, including:
obtaining a magnitude spectrum forming vector A according to the frequency spectrum sensing and the channel estimation;
random phase mapping is carried out to obtain a random phase sequence P;
performing point multiplication on the amplitude spectrum forming vector A and the random phase sequence P, and then performing conjugate operation;
after Fourier transform is carried out on the received signal, point multiplication is carried out on the received signal and the result of conjugate operation, inverse Fourier transform, a real part and CCSK coherent demodulation are carried out in sequence, wherein the received signal is the signal transmitted from the transmitter according to the information transmission method.
Specifically, due to reciprocity of the 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 according to the present invention is different from the conventional TDCS in that an equalization module is omitted and equalization is not required; in addition, when the amplitude spectrum is formed, the information receiving method provided by the present invention performs amplitude spectrum forming by comprehensively using the environmental interference power and the channel state information power (the specific amplitude spectrum forming process is consistent with that in step S103, and is not described herein again).
More specifically, the specific implementation method for performing random phase mapping at the receiving end to obtain the random phase sequence P is the same as the mapping method in the conventional TDCS, which is not limited by the present invention.
As can be seen from the figure, the receiver in the scheme can omit the equalization module, and only utilize the estimated channel state information to complete the amplitude spectrum shaping, thereby simplifying the implementation complexity of the receiver.
The invention further provides a TDCS basic modulation waveform design device, as shown in fig. 7, the device includes a channel estimation module 701, an amplitude phase matrix acquisition module 702, an amplitude spectrum forming vector acquisition module 703 and a basic modulation waveform generation module 704, where:
a channel estimation module 701, connected to the amplitude-phase matrix acquisition module 702, configured to perform channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
an amplitude phase matrix obtaining module 702, which is respectively connected to the amplitude spectrum forming vector obtaining module 703 and the basic modulation waveform generating module 704, and configured to obtain an amplitude matrix | H and a phase matrix θ according to the estimated values corresponding to the subcarriers;
an amplitude spectrum forming vector obtaining module 703, connected to the basic modulation waveform generating module 704, for generating an amplitude spectrum forming 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;
and a basic modulation waveform generating module 704, 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 perform energy adjustment to generate a basic modulation waveform B in the form of a frequency domain.
Further, the estimated value corresponding to the k sub-carrier channel state information
As shown in fig. 8, amplitude-phase matrix obtaining module 702 includes a receiving unit 7021, an amplitude matrix obtaining unit 7022, and a phase matrix obtaining unit 7023, where:
a receiving unit 7021, connected to amplitude matrix obtaining unit 7022 and phase matrix obtaining unit 7023, respectively, and configured to receive the estimated values corresponding to the subcarriers;
an amplitude matrix obtaining unit 7022, configured to obtain the estimated values corresponding to the subcarriers and a formula amplitude matrix | H | = [ | H |) 0 |,|H 1 |,…,|H N-1 |]Obtaining an amplitude matrix | H |;
wherein, | H k I and theta k Respectively representing the amplitude and phase of the frequency domain channel state information on the k-th subcarrier, k =0,1, \ 8230, N-1, N being the total number of subcarriers.
Further, as shown in fig. 9, the magnitude spectrum shaping vector obtaining module 703 includes a magnitude spectrum value obtaining unit 7031 and a magnitude spectrum shaping vector obtaining unit 7032, where:
an amplitude spectrum value obtaining unit 7031 connected to the amplitude spectrum forming vector obtaining unit 7032 for obtaining the amplitude spectrum value according to a formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k For the amplitude spectrum value A formed on the k sub-carrier k ；
An amplitude spectrum shaping vector obtaining unit 7032, configured to obtain an amplitude spectrum shaping vector according to an amplitude spectrum value formed on each subcarrier, where the amplitude spectrum shaping vector a = [ a = 0 ,A 1 ,…,A N-1 ]。
Further, in 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 the lambda is an adjustment factor,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1.
Aiming at the TDCS basic modulation waveform design method provided by the invention, the system performance simulation is carried out:
1. simulation conditions
The simulation uses a frequency domain transform method to generate a channel, and the implementation block diagram is shown in fig. 10, where the frequency domain response S (f) of the spectrum shaping filter is:
table 1 simulation parameter settings
2. Simulation result
The simulation results are shown in fig. 11, fig. 12, and fig. 13, where 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 from the figures that the time-domain basic modulation waveform generated by the present invention has the noise-like characteristic as in the conventional scheme. Fig. 12 is a diagram showing that the autocorrelation characteristic of the time-domain basic modulation waveform generated by the present invention and the cross-correlation characteristic of the time-domain basic modulation waveform generated by the present invention and the existing scheme are simulated, and it can be seen that the waveform generated by the present invention has strong autocorrelation and weak cross-correlation characteristics, and at the same time, even if an illegal user intercepts the generation strategy of the basic modulation waveform of the existing scheme, the basic modulation waveform having strong autocorrelation with a legal user cannot be generated due to different transmission channels, thereby reflecting that the present invention has stronger transmission security compared with the existing scheme. In fig. 13, the technical scheme provided by the present invention is simulated for CCSK with different modulation orders, and the frequency domain equalization is performed by using Minimum Mean Square Error (MMSE) algorithm in the existing scheme.
The terms and expressions used in the specification of the present invention have been set forth for illustrative purposes only and are not meant to be limiting. It will be appreciated by those skilled in the art that changes could be made to the details of the above-described embodiments without departing from the underlying principles thereof. The scope of the invention is, therefore, to be determined only by the following claims, in which all terms are to be interpreted in their broadest reasonable sense unless otherwise indicated.
Claims (10)
1. A TDCS basic modulation waveform design method is characterized by comprising the following steps:
performing channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier;
generating a magnitude spectrum forming vector A by using the spectrum sensing of the frequency spectrum environment where the TDCS is located, the magnitude matrix | H | and a preset subcarrier selection threshold;
and performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and performing energy adjustment to generate a basic modulation waveform B in a frequency domain form.
2. The TDCS basic modulation waveform design method according to claim 1, wherein the estimated value corresponding to the kth subcarrier channel state information
Obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier:
amplitude matrix | H | = [ | H |) 0 |,|H 1 |,…,|H N-1 |]；
Phase matrix
Wherein, | H k I and theta k Respectively representing the frequency domain channel shape on the k sub-carrierThe amplitude and phase of the state information, k =0,1, \8230, N-1, N is the number of subcarriers.
3. The TDCS basic modulation waveform design method according to claim 2, wherein the amplitude spectrum shaping vector a is generated by using spectrum sensing of a spectrum environment where the TDCS is located, the amplitude matrix | H | and a preset subcarrier selection threshold:
according to the formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k The amplitude spectrum value formed on the k sub-carrier;
obtaining a magnitude spectrum forming vector according to the magnitude spectrum value formed on each subcarrier, wherein the magnitude spectrum forming vector A = [ A = [ A ] 0 ,A 1 ,…,A N-1 ]。
4. The TDCS fundamental modulation waveform design method of claim 3, wherein the frequency domain form of the generated fundamental modulation waveform is:
wherein the lambda is an adjustment factor,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1.
5. An information transmission method, characterized in that the method comprises:
modulating information to be transmitted onto a basic modulation waveform through CCSK, and transmitting the information out 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 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 is the basic modulation waveform in the frequency domain obtained by the TDCS basic modulation waveform designing method according to any one of claims 1 to 4.
6. An information receiving method, characterized in that the method comprises:
obtaining a magnitude spectrum forming vector A according to frequency spectrum sensing and channel estimation;
random phase mapping is carried out to obtain a random phase sequence P;
performing point multiplication on the amplitude spectrum forming vector A and the random phase sequence P, and then performing conjugate operation;
after performing fourier transform on a received signal, performing point multiplication on a conjugate operation result, and then sequentially performing inverse fourier transform, a real part and CCSK coherent demodulation, wherein the received signal is a signal transmitted from the transmitter according to the information transmission method of claim 6.
7. A TDCS basic modulation waveform design device is characterized by comprising a channel estimation module, an amplitude phase matrix acquisition module, an amplitude spectrum forming 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 performing channel estimation on the frequency domain channel state information on each subcarrier to obtain an estimation value corresponding to each subcarrier;
the amplitude phase matrix acquisition module is respectively connected with the amplitude spectrum forming vector acquisition module and the basic modulation waveform generation module and is used for obtaining an amplitude matrix | H | and a phase matrix theta according to the estimation value corresponding to each subcarrier;
the amplitude spectrum forming vector acquisition module is connected with the basic modulation waveform generation module and is used for generating an amplitude spectrum forming vector A by utilizing the frequency spectrum sensing, the amplitude matrix | H | and a preset subcarrier selection threshold of the frequency spectrum environment where the TDCS is located;
and the basic modulation waveform generation module is used for performing point multiplication on the random phase sequence P obtained by mapping, the amplitude spectrum forming vector A and the conjugate of the phase matrix theta, and generating a basic modulation waveform B in a frequency domain form through energy adjustment.
8. The TDCS basic modulation waveform design apparatus of claim 7, wherein the estimated value corresponding to the k-th sub-carrier channel state information
The amplitude and 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 acquiring unit and the phase matrix acquiring unit and is used for receiving the estimation value corresponding to each subcarrier;
the amplitude matrix obtaining unit is configured to: amplitude matrix | H | = [ | H 0 |,|H 1 |,…,|H N-1 |]Obtaining an amplitude matrix | H |;
the phase matrix obtaining unit is configured to, according to the estimated value corresponding to each subcarrier and a formula: phase matrix
Obtaining 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 k-th subcarrier, k =0,1, \ 8230, N-1, N being the number of subcarriers.
9. The TDCS fundamental modulation waveform design device of claim 7, wherein the magnitude spectrum shaped vector acquisition module comprises a magnitude spectrum value acquisition unit and a magnitude spectrum shaped vector acquisition unit, wherein:
the amplitude spectrum value obtaining unit, andthe amplitude spectrum forming vector obtaining unit is connected and used for obtaining the amplitude spectrum forming vector according to a formula
Obtaining the amplitude spectrum value formed on each subcarrier, wherein A k For the amplitude spectrum value A formed on the k sub-carrier k ；
The amplitude spectrum forming vector obtaining unit is used for obtaining an amplitude spectrum forming vector according to the amplitude spectrum value formed on each subcarrier, wherein the amplitude spectrum forming vector A = [ A = 0 ,A 1 ,…,A N-1 ]。
10. The TDCS fundamental modulation waveform design apparatus of claim 7, wherein the fundamental modulation waveform generated by the fundamental modulation waveform generation module has a frequency domain form of:
wherein the lambda is an adjustment factor,
ε s representing the energy required to transmit a symbol, N A Indicating the number of subcarriers having an amplitude spectrum value of 1.
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