CN106850021B - Method and device for realizing wireless communication physical layer safety based on polarization precoding - Google Patents

Method and device for realizing wireless communication physical layer safety based on polarization precoding Download PDF

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CN106850021B
CN106850021B CN201710063601.0A CN201710063601A CN106850021B CN 106850021 B CN106850021 B CN 106850021B CN 201710063601 A CN201710063601 A CN 201710063601A CN 106850021 B CN106850021 B CN 106850021B
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singular value
communication
channel
value decomposition
weighting
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CN106850021A (en
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李敏
梁莉莉
魏冬
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Institute of Information Engineering of CAS
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/046—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • 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
    • H04L63/16—Implementing security features at a particular protocol layer

Abstract

The invention provides a method and a device for realizing wireless communication physical layer security based on polarization precoding. The method comprises the following steps: receiving communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence; obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel; carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points; determining a weighting set according to the singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation points to obtain symbols to be sent; and transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna. The embodiment of the invention disturbs the signal polarization constellation points received by the eavesdropper by deteriorating the quality of the eavesdropping channel, thereby greatly increasing the difficulty of information decoding; the quick change of the equivalent channel is realized by quickly changing the precoding factor, so that an eavesdropper is effectively prevented from acquiring information. Meanwhile, replay attack can be effectively prevented.

Description

Method and device for realizing wireless communication physical layer safety based on polarization precoding
Technical Field
The invention relates to the technical field of communication, in particular to a method and a device for realizing wireless communication physical layer security based on polarization precoding.
Background
With the rapid development of wireless communication technology and the increasing application demand, the security problem of wireless communication transmission becomes more and more important. Due to the openness and the broadcasting characteristic of a wireless communication link, a signal bearing important information is completely exposed in an electromagnetic space, and any person in a transmission range can intercept and analyze the signal, so that the wireless communication system has a huge potential safety hazard of information leakage.
At present, most of security protection measures only cover a link layer and a higher layer of a communication protocol stack, and the security transmission problem of wireless communication, such as application of a symmetric key encryption algorithm and a public key encryption algorithm, is solved by means of authentication and a cryptographic technology. As the processing power of computers increases, such a weak security scheme based on the computing power faces a great challenge. Moreover, with such higher-level wireless communication protocols, the physical layer information is vulnerable to eavesdropping and malicious attacks. For an eavesdropper with a known transmission protocol, the signal transmitted by the physical layer is transparent, and can easily receive the signal and recover the intercepted information. Therefore, the physical layer security problem has become an urgent problem to be solved in wireless communication.
The physical layer security technology can directly prevent a malicious attacker from acquiring transmission information based on an open transmission medium. A method for realizing physical layer safety communication by adding artificial noise is provided from the perspective of reducing the quality of an eavesdropping channel in the existing physical layer safety realization method, when a transmitting end is provided with a plurality of antennas, the quality difference between a main channel and the eavesdropping channel can be increased by designing to transmit signals in the main channel direction and transmit noise in other directions. In a multi-antenna transmission single-antenna receiving model, a desired directional pattern is formed by adjusting weighting vectors of each antenna unit of an antenna array by using a difference between a main channel and an eavesdropping channel direction, a main beam is tuned to the main channel direction, and null is generated in the eavesdropping channel direction.
However, the beamforming technique requires that the transmitting end knows all or part of the state information of the main channel and the intercepted channel, and in practical system applications, the transmitting end is difficult to obtain the intercepted channel information, and is also difficult to avoid channel estimation errors, and the problem of random error constraint needs to be considered. On the other hand, although the artificial noise technology does not need to know the eavesdropping channel information, the power allocation and optimization of noise and useful signals need to be considered, the number of the antennas at the transmitting end is required to be more than that of the eavesdropping end, and the artificial noise technology is difficult to guarantee in a practical model.
Disclosure of Invention
The embodiment of the invention provides a method and a device for realizing wireless communication physical layer security based on polarization precoding, which are used for solving the problems that the existing wiretapping channel information is difficult to obtain and the number of wiretapping end antennas needs to be limited.
The embodiment of the invention provides a wireless communication physical layer security realization method based on polarization precoding, which comprises the following steps:
receiving communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence;
obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel;
carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points;
determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation point to obtain a symbol to be sent;
and transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna.
Optionally, the performing singular value decomposition on the channel matrix of the legal communication channel includes:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure BDA0001220054200000021
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure BDA0001220054200000031
and
Figure BDA0001220054200000032
is a singular value, satisfies lambdaAB,1≥λAB,2＞0。
Optionally, the performing polarization state modulation on source bits to be transmitted to obtain symbol constellation points includes:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure BDA0001220054200000033
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation (a)k,φk) Is a descriptor of the polarization state, 0 ≦k≤π/2，-π≤φkLess than pi; j is an imaginary unit.
Optionally, the determining a weighted set according to the singular value decomposition result includes:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure BDA0001220054200000034
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure BDA0001220054200000035
and
Figure BDA0001220054200000036
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
The embodiment of the invention provides a wireless communication physical layer security realization method based on polarization precoding, which comprises the following steps:
receiving a carrier modulation signal sent by a communication sender through an orthogonal dual-polarized antenna;
the carrier modulation signal is multiplied by a coding matrix to obtain a receiving signal;
and demodulating the received signal to extract a transmission symbol.
The embodiment of the invention provides a device for realizing the safety of a wireless communication physical layer based on polarization precoding, which comprises the following steps:
a communication request information receiving unit, configured to receive communication request information sent by a communication receiving side, where the communication request information includes a pilot sequence;
the singular value decomposition unit is used for acquiring a legal communication channel according to the pilot frequency sequence and carrying out singular value decomposition on a channel matrix of the legal communication channel;
a symbol constellation point obtaining unit, configured to perform polarization state modulation on an information source bit to be transmitted to obtain a symbol constellation point;
the weighting processing unit is used for determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and carrying out weighting processing on the symbol constellation point to obtain a symbol to be sent;
and the symbol transmitting unit is used for transmitting the symbol to be transmitted outwards through an orthogonal dual-polarized antenna.
Optionally, the singular value decomposition unit is further configured to:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure BDA0001220054200000041
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure BDA0001220054200000042
and
Figure BDA0001220054200000043
is a singular value, satisfies lambdaAB,1≥λAB,2＞0。
Optionally, the symbol constellation point obtaining unit is further configured to:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure BDA0001220054200000044
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation (a)k,φk) Is a descriptor of the polarization state, 0 ≦k≤π/2，-π≤φkLess than pi; j is an imaginary unit.
Optionally, the weighting processing unit is further configured to:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure BDA0001220054200000051
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure BDA0001220054200000052
and
Figure BDA0001220054200000053
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
The embodiment of the invention provides a device for realizing the safety of a wireless communication physical layer based on polarization precoding, which comprises the following steps:
the carrier modulation signal receiving unit is used for receiving a carrier modulation signal sent by a communication sender through an orthogonal dual-polarized antenna;
a received signal obtaining unit, configured to obtain a received signal by left-multiplying the carrier modulation signal by a coding matrix;
and the transmitting symbol extraction unit is used for demodulating the receiving signal and extracting a transmitting symbol.
The method and the device for realizing the safety of the wireless communication physical layer based on the polarization precoding receive the communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence; obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel; carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points; determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation point to obtain a symbol to be sent; and transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna. The embodiment of the invention fully utilizes the characteristics of the wireless channel to seriously deteriorate the quality of the wiretap channel and disturb the polarization constellation points of the signal received by a wiretap, thereby greatly increasing the difficulty of decoding the information; under the slowly changing environment of the channel, the quick change of the equivalent channel is realized through the quick change of the precoding factor, and the eavesdropper is effectively prevented from acquiring information. Meanwhile, replay attack can be effectively prevented.
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 introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart illustrating a method for implementing security of a wireless communication physical layer based on polarization precoding according to an embodiment of the present invention;
FIG. 2 is a schematic representation of the polarization state on a Poincare sphere according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a method for implementing security of a physical layer of wireless communication based on polarization pre-coding according to an embodiment of the present invention;
FIG. 4 is a constellation diagram of 4-POLSK according to one embodiment of the invention;
fig. 5 is a flowchart of a method for implementing security of a wireless communication physical layer based on polarization precoding according to another embodiment of the present invention;
FIG. 6 is a constellation diagram of 4-POLSK recovered by Eve when the received signal-to-noise ratio is 30dB according to the embodiment of the present invention;
FIG. 7a is a constellation diagram of 4-POLSK recovered by Bob when the received signal-to-noise ratio is 30dB in view 1 according to the embodiment of the present invention;
FIG. 7b is a constellation diagram of 4-POLSK recovered by Bob when the received signal-to-noise ratio is 30dB in view 2 according to the embodiment of the present invention;
fig. 8 is a schematic structural diagram of a wireless communication physical layer security implementation apparatus based on polarization precoding according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a wireless communication physical layer security implementation apparatus based on polarization precoding according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. 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.
The basic idea of the physical layer security technology is to make the main channel have greater channel advantage than the eavesdropping channel by using the characteristics of spatial uniqueness, short-time reciprocity, non-detectability and the like of the wireless channel. The method does not need to limit the computing power of an attacker, and can effectively avoid the problems of complex key distribution and management in the traditional encryption algorithm.
Fig. 1 is a flowchart illustrating a method for implementing security of a wireless communication physical layer based on polarization precoding according to an embodiment of the present invention. As shown in fig. 1, the method of this embodiment takes a communication sender as an execution subject, and includes:
s11: receiving communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence;
it should be noted that, in the embodiment of the present invention, the communication receiving side and the communication transmitting side transmit the communication request information without being subjected to the precoding processing, which includes the pilot sequence known to both communication parties for channel estimation. S12: obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel;
it should be noted that, in the embodiments of the present invention, both communication parties estimate a legal communication channel by using a minimum mean square error estimation MMSE method based on a pilot sequence.
S13: carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points;
it should be noted that, according to the antenna theory, in the far field region with a given frequency and spatial orientation, the antenna has a certain polarization mode, and the polarization mode of the antenna radiation field is different according to the operating frequency and spatial orientation. In addition to amplitude, phase and frequency, which may carry user information, the polarization state of a signal may also be used to carry information.
The two communication parties of the embodiment of the invention adopt a polarization state modulation and demodulation scheme, the adopted communication system model is orthogonal dual-polarized antenna transmission and orthogonal dual-polarized antenna reception, the system is Time Division Duplex (TDD), and the channel is slowly changed to meet reciprocity. The eavesdropper also receives using an orthogonal dual polarized antenna. The legal communication sender is marked as Alice, the legal communication receiver is marked as Bob, and the eavesdropper is marked as Eve.
S14: determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation point to obtain a symbol to be sent;
it should be noted that, in the embodiments of the present invention, polarization precoding is introduced to deteriorate the reception quality of the eavesdropping channel, thereby ensuring the secure transmission of information. This method does not require the known eavesdropping channel information and does not impose any restrictions on the number of eavesdropper antennas.
S15: and transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna.
The method for safely realizing the wireless communication physical layer based on the polarization precoding provided by the embodiment of the invention fully utilizes the characteristics of the wireless channel to seriously deteriorate the quality of the wiretap channel and disturb the polarization constellation points of the signal received by a wiretap, thereby greatly increasing the difficulty of decoding the information; under the slowly changing environment of the channel, the quick change of the equivalent channel is realized through the quick change of the precoding factor, and the eavesdropper is effectively prevented from acquiring information. Meanwhile, replay attack can be effectively prevented.
The embodiment of the invention is different from the traditional amplitude, phase and frequency modulation, and utilizes the polarization state of the signal to carry information. The polarization state for any electromagnetic vector signal can be represented by the Jones and Stoke vectors as follows:
Figure BDA0001220054200000081
wherein pi/2 is more than or equal to 0 and less than or equal to phi and phi is less than or equal to pi; (, φ) is called a descriptor of the polarization state, tan represents the amplitude ratio of the vertical and horizontal branch signals, and φ represents the phase difference.
It can be seen that any polarization state of a signal can be represented by the amplitude ratio and phase difference of the horizontal and vertical polarization components, and can be uniquely characterized by (, phi). In either polarization state, there is a unique point (g) on the unit Poincare sphere1,g2，g3) Corresponding thereto, 2 is P to the horizontally polarized state PHPhi is the angle between the arc and the equator of the sphere, as shown in figure 2. In theory, any amplitude ratio and phase difference characterization information can be used, and the discrete polarization states are used for analysis in the present invention.
Further, the performing singular value decomposition on the channel matrix of the legal communication channel includes:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure BDA0001220054200000091
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure BDA0001220054200000092
and
Figure BDA0001220054200000093
is a singular value, satisfies lambdaAB,1≥λAB,2＞0。
Optionally, the performing polarization state modulation on source bits to be transmitted to obtain symbol constellation points includes:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure BDA0001220054200000094
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation (a)k,φk) Is a descriptor of the polarization state, 0 ≦k≤π/2，-π≤φkLess than pi; j is an imaginary unit.
In practical application, Alice performs framing and grouping on source bits to be transmitted, and obtains symbol constellation points by using POLarization Shift Keying (POLSK).
Further, the determining a weighted set according to the singular value decomposition result includes:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure BDA0001220054200000095
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure BDA0001220054200000096
and
Figure BDA0001220054200000097
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
The embodiment of the invention describes the sub (according to the polarization state corresponding to the symbol constellation point), (k,φk) Determining a set of precoding matrices Ck(pseudo-) randomly selecting one of them as a precoding matrix factor CpAdding to the constellation pointsThe weighted signals are transmitted by a horizontal-vertical orthogonal dual-polarized antenna in the modulation modes of 2-POLSK, 4-POLSK and 8-POLSK, and the modulation order M in the embodimentp＝4，N＝3。
The power of the polarization signal is not changed after the symbols are precoded. Thus, for each amplitude ratio factorkAll correspond to 12 weighting matrix alternatives, for MpPOLSK, if there is MThe amplitude ratio factor is 2 × M× 6 weighting matrixes can be selected, one weighting matrix corresponds to one channel, the specific selection sequence is jointly appointed by Alice and Bob, and in this way, the rapid change of the equivalent channel under the slowly-changed channel is realized.
In the examples of the present invention, Mp4 or so on
Figure BDA0001220054200000101
And
Figure BDA0001220054200000102
Figure BDA0001220054200000103
four polarization states description mapping four polarization states as an example for analysis, distribution on Poincare sphere is shown in FIG. 4, then there is M1. Then to SnPre-coding weighting is carried out to obtain the final modulated symbol
Figure BDA0001220054200000104
The Jones vector of the modulated digital baseband signal is represented as follows:
Figure BDA0001220054200000105
where A is the amplitude of the signal, xH(t) and xv(t) represents horizontal and vertical polarization components, respectively. T is the symbol period, uT(t) is a shaping filter function, in this embodiment raised cosine shaping filtering is used, and the roll-off factor is 0.35.
And finally, transmitting the weighted symbols through a horizontal-vertical orthogonal dual-polarized antenna by processing such as up-conversion and the like.
Fig. 5 is a flowchart illustrating a method for implementing security of a wireless communication physical layer based on polarization precoding according to another embodiment of the present invention. As shown in fig. 5, the method of this embodiment takes a communication recipient as an execution subject, and includes:
s51: receiving a carrier modulation signal sent by a communication sender through an orthogonal dual-polarized antenna;
s52: the carrier modulation signal is multiplied by a coding matrix to obtain a receiving signal;
s53: and demodulating the received signal to extract a transmission symbol.
The method for safely realizing the wireless communication physical layer based on the polarization precoding provided by the embodiment of the invention fully utilizes the characteristics of the wireless channel to seriously deteriorate the quality of the wiretap channel and disturb the polarization constellation points of the signal received by a wiretap, thereby greatly increasing the difficulty of decoding the information; under the slowly changing environment of the channel, the quick change of the equivalent channel is realized through the quick change of the precoding factor, and the eavesdropper is effectively prevented from acquiring information. Meanwhile, Bob cannot identify the signal sent by Alice forwarded by Eve, and replay attack can be effectively prevented.
Specifically, Bob receives a carrier-modulated signal using an orthogonal dual-polarized antenna, down-converts it to a digital baseband signal, and left-multiplies the coding matrix DnAnd then obtaining a receiving symbol:
Figure BDA0001220054200000111
Figure BDA0001220054200000112
wherein, wB,nFor the purpose of noise in a legitimate communication channel,
Figure BDA0001220054200000113
bob uses maximum likelihood method to demodulate and judge the symbol, and extracts the sending information;
Figure BDA0001220054200000114
where dist (X, Y) is the spherical distance calculated for polarization states X and Y corresponding on the unit Poincare sphere.
Likewise, Eve receives signals using an orthogonal dual polarized antenna. Since the radio channel conditions are uncorrelated when the two receivers are half a wavelength apart. Therefore, in practical applications, it is generally satisfied that two wireless channels are uncorrelated. Thus, the signal received by Eve is represented as follows:
Figure BDA0001220054200000115
if M is in the selected modulation constellationSeed amplitude ratio factorkThen Alice has 2 × M× 2N precoding coefficients can be selected, the signal constellation diagram is subjected to (pseudo) random rigid rotation and power conversion, the rapid change of the precoding coefficients enables an eavesdropping user not to decode by a blind equalization method, if the eavesdropping user adopts a maximum likelihood method for decoding, the error rate is more than 50 percent, and therefore, the physical layer safety transmission of information can be realized by the polarization state modulation technology of polarization precoding.
Even if noise is not considered, the information received by Eve is random disturbance to the amplitude and phase of the original symbol, the constellation diagram is seriously distorted, and the information cannot be directly decoded through the maximum likelihood criterion. Through precoding, the fast changing channel makes it difficult for Eve to acquire information through blind equalization algorithm, thereby ensuring the safe transmission of information. In the invention, the channel is equivalent to a fast-changing channel through polarization pre-coding, and the received symbol constellation diagram of the eavesdropping end can generate serious distortion, thereby achieving the purpose of deteriorating the quality of the eavesdropping channel.
FIG. 6 is a constellation diagram of 4-POLSK recovered by Eve when the received signal-to-noise ratio is 30dB according to the embodiment of the present invention; FIG. 7a is a constellation diagram of 4-POLSK recovered by Bob when the received signal-to-noise ratio is 30dB in view 1 according to the embodiment of the present invention; fig. 7b is a constellation diagram of 4-POLSK recovered by Bob when the received signal-to-noise ratio is 30dB in view 2 according to the embodiment of the present invention. As shown in fig. 6 and fig. 7a and 7b, the constellation of Bob is regular, while even at high received signal-to-noise ratio, the constellation received by Eve is divergent, and if four constellation points select different amplitude ratio factors, the constellation is more divergent.
Fig. 8 is a schematic structural diagram of a wireless communication physical layer security implementation apparatus based on polarization precoding according to an embodiment of the present invention. As shown in fig. 8, the apparatus according to the embodiment of the present invention includes a communication request information receiving unit 81, a singular value decomposition unit 82, a symbol constellation point obtaining unit 83, a weighting processing unit 84, and a symbol transmitting unit 85, specifically:
a communication request information receiving unit 81, configured to receive communication request information sent by a communication receiving side, where the communication request information includes a pilot sequence;
a singular value decomposition unit 82, configured to obtain a legal communication channel according to the pilot sequence, and perform singular value decomposition on a channel matrix of the legal communication channel;
a symbol constellation point obtaining unit 83, configured to perform polarization state modulation on an information source bit to be sent to obtain a symbol constellation point;
a weighting processing unit 84, configured to determine a weighting set according to a singular value decomposition result, select a weighting factor from the weighting set, and perform weighting processing on the symbol constellation point to obtain a symbol to be sent;
and a symbol transmitting unit 85, configured to transmit the symbol to be transmitted outwards through an orthogonal dual-polarized antenna.
The singular value decomposition unit 82 is further configured to:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure BDA0001220054200000121
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure BDA0001220054200000131
and
Figure BDA0001220054200000132
is a singular value, satisfies lambdaAB,1≥λAB,2＞0。
The symbol constellation point obtaining unit 83 is further configured to:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure BDA0001220054200000133
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation (a)k,φk) Is a descriptor of the polarization state, 0 ≦k≤π/2，-π≤φkLess than pi; j is an imaginary unit.
The weighting processing unit 84 is further configured to:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure BDA0001220054200000134
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure BDA0001220054200000135
and
Figure BDA0001220054200000136
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
Fig. 9 is a schematic structural diagram of a wireless communication physical layer security implementation apparatus based on polarization precoding according to an embodiment of the present invention. As shown in fig. 9, the apparatus of the embodiment of the present invention includes a carrier modulation signal receiving unit 91, a received signal acquiring unit 92, and a transmission symbol extracting unit 93, specifically:
a carrier modulated signal receiving unit 91, configured to receive, through an orthogonal dual-polarized antenna, a carrier modulated signal sent by a communication sender;
a received signal obtaining unit 92, configured to obtain a received signal by left-multiplying the carrier modulation signal by a coding matrix;
a transmit symbol extracting unit 93, configured to demodulate the received signal and extract a transmit symbol.
The apparatus of the embodiment of the present invention may be used to implement the above method embodiments, and the principle and technical effect are similar, which are not described herein again.
The method and the device for realizing the safety of the wireless communication physical layer based on the polarization precoding receive the communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence; obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel; carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points; determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation point to obtain a symbol to be sent; and transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna. The embodiment of the invention fully utilizes the characteristics of the wireless channel to seriously deteriorate the quality of the wiretap channel and disturb the polarization constellation points of the signal received by a wiretap, thereby greatly increasing the difficulty of decoding the information; under the slowly changing environment of the channel, the quick change of the equivalent channel is realized through the quick change of the precoding factor, and the eavesdropper is effectively prevented from acquiring information. Meanwhile, replay attack can be effectively prevented.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the description of the present invention, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
The above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (4)

1. A method for realizing wireless communication physical layer security based on polarization precoding is characterized by comprising the following steps:
receiving communication request information sent by a communication receiver, wherein the communication request information comprises a pilot frequency sequence;
obtaining a legal communication channel according to the pilot frequency sequence, and performing singular value decomposition on a channel matrix of the legal communication channel;
carrying out polarization state modulation on information source bits to be transmitted to obtain symbol constellation points;
determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and performing weighting processing on the symbol constellation point to obtain a symbol to be sent;
transmitting the symbols to be transmitted outwards through an orthogonal dual-polarized antenna;
the performing singular value decomposition on the channel matrix of the legitimate communication channel includes:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure FDA0002483684800000011
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure FDA0002483684800000012
and
Figure FDA0002483684800000013
is a singular value, satisfies lambdaAB,1≥λAB,2＞0；
The determining a weighted set according to the singular value decomposition result includes:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure FDA0002483684800000014
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure FDA0002483684800000015
and
Figure FDA0002483684800000016
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
2. The method of claim 1, wherein the performing polarization state modulation on source bits to be transmitted to obtain symbol constellation points comprises:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure FDA0002483684800000021
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation,
Figure FDA0002483684800000022
is a descriptor of the polarization state, 0 ≦k≤π/2，
Figure FDA0002483684800000023
j is an imaginary unit.
3. A device for realizing security of a wireless communication physical layer based on polarization precoding is characterized by comprising the following components:
a communication request information receiving unit, configured to receive communication request information sent by a communication receiving side, where the communication request information includes a pilot sequence;
the singular value decomposition unit is used for acquiring a legal communication channel according to the pilot frequency sequence and carrying out singular value decomposition on a channel matrix of the legal communication channel;
a symbol constellation point obtaining unit, configured to perform polarization state modulation on an information source bit to be transmitted to obtain a symbol constellation point;
the weighting processing unit is used for determining a weighting set according to a singular value decomposition result, selecting a weighting factor from the weighting set, and carrying out weighting processing on the symbol constellation point to obtain a symbol to be sent;
the symbol transmitting unit is used for transmitting the symbol to be transmitted outwards through an orthogonal dual-polarized antenna;
the singular value decomposition unit is further to:
performing singular value decomposition on the channel matrix of the legitimate communication channel according to the following formula:
Figure FDA0002483684800000024
wherein HABA legal communication channel from a communication sender to a communication receiver; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABThe conjugate transpose of (1);
Figure FDA0002483684800000025
and
Figure FDA0002483684800000026
is a singular value, satisfies lambdaAB,1≥λAB,2＞0；
The weighting processing unit is further configured to:
determining a weighted set from the singular value decomposition results according to the following formula:
Figure FDA0002483684800000031
wherein, CkIs a weighted set; u shapeABAnd VABUnitary matrix of 2 × 2, VAB *Is shown as VABBy conjugate transposition of UAB *Is denoted as UABThe conjugate transpose of (1);
Figure FDA0002483684800000032
and
Figure FDA0002483684800000033
is a singular value, satisfies lambdaAB,1≥λAB,2Is greater than 0; n is a positive integer.
4. The apparatus of claim 3, wherein the symbol constellation point obtaining unit is further configured to:
carrying out polarization state modulation on source bits to be transmitted according to the following formula to obtain symbol constellation points:
Figure FDA0002483684800000034
wherein S isnIs a symbol constellation point; mpIs the order of the polarization state modulation,
Figure FDA0002483684800000035
is a descriptor of the polarization state, 0 ≦k≤π/2，
Figure FDA0002483684800000036
j is an imaginary unit.
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