Wireless channel decorrelation method based on spatial position

Abstract

The invention discloses a wireless channel decorrelation method based on a spatial position. The method comprises the following steps: S1, a legal sender estimates the spatial position of an original channel and the spatial position of a legal receiver according to a pilot signal sent by the legal receiver; s2, the legal sender designs a pre-coding matrix according to the spatial position of the legal receiver, and converts the original channel into an equivalent channel according to the pre-coding matrix; s3, the legal sender performs pre-coding processing on a pilot signal according to the pre-coding matrix, and sends the signal after pre-coding processing to the legal receiver; and S4, the legal receiver receives the pre-coded signal from the legal sender, and performs channel estimation according to the received signal to obtain an equivalent channel. A pre-coding matrix is designed by a legal sender based on the spatial position of a legal receiver, so that the correlation between a legal channel and an eavesdropping channel is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication security, and in particular to a channel decorrelation method for wireless communication, and in particular to a wireless channel decorrelation method based on spatial position. Background Art

[0002] The main feature of the physical layer key generation technology based on wireless channels is that the legitimate communicating parties generate keys based on the channel information obtained during the channel estimation process and use them to encrypt communications. Users at other locations other than the legitimate communicating parties cannot generate the same key as the legitimate party due to irrelevant channels, and therefore cannot break the encryption.

[0003] The security feature of this technology stems from the diversity of electromagnetic wave propagation mechanisms and propagation environments, that is, when a transmitted signal reaches users at multiple locations through different propagation routes, there are differences between the different wireless channels experienced. This difference is related to the spatial distance between different users. Generally, the greater the distance between two users, the greater the channel difference. When a certain distance is exceeded (for example, several signal carrier wavelengths), the channels of the two are irrelevant. Therefore, as long as the eavesdropper is at a certain distance away from the legitimate user, the legitimate channel is irrelevant to the eavesdropping channel, and the eavesdropper cannot obtain information about the legitimate channel (for example, channel amplitude, phase, etc.) through its own eavesdropping channel, while the legitimate user can use the legitimate channel information to generate a key.

[0004] However, when the distance between the eavesdropper and the legitimate user is small, the technology may fail due to the correlation between the legitimate channel and the eavesdropping channel. Therefore, how to reduce the correlation between the legitimate channel and the eavesdropping channel when the distance between the eavesdropper and the legitimate user is a problem that needs to be solved. Summary of the invention

[0005] In order to solve the problem in the prior art that it is impossible to ensure that the legitimate channel is uncorrelated with the eavesdropping channel when the distance between the eavesdropper and the legitimate user is small, the present invention proposes a wireless channel decorrelation method based on spatial position, in which the legitimate sender designs a precoding matrix according to the spatial position of the legitimate receiver, thereby reducing the correlation between the legitimate channel and other direction channels (such as the eavesdropping channel).

[0006] In a first aspect, the present invention provides a wireless channel decorrelation method based on spatial position, comprising the following steps:

[0007] Step S1: The legitimate sender estimates the original channel and the spatial position of the legitimate receiver based on the pilot signal sent by the legitimate receiver;

[0008] Step S2: the legal sender designs a precoding matrix according to the spatial position of the legal receiver, and converts the original channel into an equivalent channel according to the precoding matrix;

[0009] Step S3: the legitimate sender performs precoding processing on the pilot signal according to the precoding matrix, and sends the precoded signal to the legitimate receiver;

[0010] Step S4: The legal receiver receives the precoded signal from the legal sender, performs channel estimation based on the received signal, and obtains an equivalent channel.

[0011] Furthermore, in step S2, the legal sender designs a precoding matrix according to the spatial position of the legal receiver, including:

[0012] Step S201: the legitimate sender adopts an orthogonal beam design method to obtain an orthogonal beam matrix;

[0013] Step S202: the legal sender calculates a steering matrix according to the spatial position of the legal receiver;

[0014] Step S203: the legitimate sender generates a random perturbation vector, and obtains an anisotropic beam according to the orthogonal beam matrix and the random perturbation vector;

[0015] Step S204: The legitimate sender obtains a precoding matrix according to the anisotropic beam and the steering matrix.

[0016] Furthermore, in step S201, the orthogonal beam matrix is ​​expressed as follows:

[0017]

[0018] Among them, N A Indicates the number of array elements of the legal transmitter antenna, a i represents the first i∈0,1,…,N A -1 direction codebook, satisfying a i H a j =0, i, j = 0, ..., N A -1, i≠j.

[0019] Furthermore, the random perturbation vector in step S203 follows a complex Gaussian distribution, which is expressed as follows:

[0020]

[0021] Where R represents the random perturbation vector, N A Indicates the number of array elements of the legal transmitter antenna, σ l represents the standard deviation, and r i Any two random variables in are independent of each other.

[0022] Furthermore, the anisotropic beam in step S203 satisfies the following relationship:

[0023] W 0 =AR

[0024] Among them, W 0 represents anisotropic beam, A represents orthogonal beam matrix, and R represents random perturbation vector.

[0025] Furthermore, the precoding matrix in step S204 satisfies the following relationship:

[0026] W=diag(S)W 0

[0027] Where W represents the precoding matrix, S represents the steering matrix, and the diag function is used to construct a diagonal matrix. 0 represents an anisotropic beam.

[0028] Furthermore, in step S2, the equivalent channel calculation formula is as follows:

[0029] G AB =H AB H W

[0030] Among them, G AB represents the equivalent channel, H AB represents the original channel, H AB H Indicates H AB The conjugate of , W represents the precoding matrix.

[0031] In a second aspect, the present invention provides a key generation method for wireless channel decorrelation based on spatial position, comprising:

[0032] The two legal communicating parties obtain their respective equivalent channels based on the wireless channel decorrelation method;

[0033] The two parties in legitimate communication generate keys based on their respective equivalent channels.

[0034] In a third aspect, the present invention provides a communication device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the method is implemented when the processor executes the program.

[0035] In a fourth aspect, the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the above method when executed by a processor.

[0036] Compared with the prior art, the present invention has the following technical effects:

[0037] The present invention proposes a wireless channel decorrelation method based on spatial position, wherein the legal transmitter designs the transmission precoding according to the spatial position of the legal receiver, and forms orthogonal and randomly scrambled transmission beams, thereby constructing mutually orthogonal equivalent channels in each sidelobe direction of the transmission beam. Since one of the sidelobe directions of the transmission beam is aimed at the legal receiver, and the signals transmitted in the other sidelobe directions are independent of the signals transmitted in the direction of the legal receiver, the correlation between the legal channel and the channels in other directions can be reduced, making it more difficult for the channel information of the two legal communication parties to be obtained by illegal eavesdroppers in other directions, so the security and privacy of the legal channel information are better, and the legal channel information can also be used for physical layer key generation.

[0038] The present invention proposes a key generation method based on spatial position wireless channel decorrelation, and uses the legitimate channel information generated by the spatial position wireless channel decorrelation method to generate physical layer keys. By increasing the difference between the legitimate channels of the legitimate communicating parties and the eavesdropping channels of users at different locations, that is, reducing the correlation between the legitimate channels and the eavesdropping channels, the security of the physical layer key generation technology is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the spatial positions of a legitimate sender, a legitimate receiver, and a simulated eavesdropper provided in an embodiment of the present invention;

[0040] Figure 2 A schematic flow chart of a wireless channel decorrelation method based on spatial position provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the physical structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The wireless channel decorrelation method based on spatial position provided by the present invention is described in detail below with reference to the accompanying drawings. In practical applications, there are the following communication scenarios: the legitimate sender and the legitimate receiver are Alice and Bob, respectively, each equipped with N A and N B uniform linear array antennas. The eavesdropper is Eve, equipped with N E Uniform linear array antenna with array elements. Figure 1 As shown, the position coordinates of Alice, Bob, and Eve are (x A ,y A ,z A )、(x B ,y B ,z B ) and (x E ,y E ,z E ). Without loss of generality, we assume that Eve is close to Bob, so that the Alice-Bob channel Channel with Alice-Eve Correlation, resulting in channel H AB With channel H AE The difference is reduced and the correlation is increased, that is, Η AB ≈H AE In order to solve this problem, the invention is conceived as follows: the legal party constructs an anisotropic composite channel by designing and sending a precoding matrix W. and Thus increasing the Alice-Bob channel G AB With Alice-Eve channel G AE The difference between G AB With G AE The correlation between H AE or G AE Get more information about G AB Based on the inventive concept, the more specific technical solutions of the present invention can be found in the following embodiments. It can be understood that the present invention only takes the uniform linear array antenna as an example and does not limit the shape of the antenna array of the legitimate sender.

[0044] like Figure 2 As shown, the wireless channel decorrelation method based on spatial position provided by an embodiment of the present invention includes the following steps:

[0045] Step S1: The legitimate sender estimates the original channel and the spatial position of the legitimate receiver based on the pilot signal sent by the legitimate receiver;

[0046] For the convenience of description, the original channel is represented as H in the present invention. AB, refers to the communication channel between Alice and Bob when no precoding is used, and is the medium for Alice and Bob to transmit signals. Channel estimation methods include common algorithms such as least squares and minimum mean square error.

[0047] In this embodiment, the spatial position of the legal receiver Bob refers to the specific direction of the legal receiver Bob relative to the legal sender Alice, expressed as the direction angle θ B ∈(0,2π) represents.

[0048] It can be understood that if the simulated eavesdropper Eve is close to the legitimate receiver Bob, the original channel H between Alice and Bob AB The original channel H with Alice-Eve AE The difference is small and the correlation is large, that is, Η AB ≈H AE .

[0049] Step S2: The legitimate sender designs a precoding matrix according to the spatial position of the legitimate receiver, and converts the original channel into an equivalent channel according to the precoding matrix;

[0050] Specifically, the legitimate sender Alice determines the spatial position θ of the legitimate receiver Bob. B Design the precoding matrix W.

[0051] Step S201: The legitimate sender adopts an orthogonal beam design method to obtain an orthogonal beam matrix;

[0052] Specifically, since the legitimate sender Alice is equipped with N A antennas, so it is necessary to use the orthogonal beam design method to obtain an N A *N A dimensional orthogonal beam matrix A:

[0053]

[0054] Among them, N A Indicates the number of array elements of the legal transmitter antenna, a i represents the first i∈0,1,…,N A -1 direction codebook, satisfying a i H a j =0, i, j = 0, ..., N A -1, i≠j.

[0055] As an implementation method, in this embodiment, the orthogonal codebook is generated by the DFT (discrete Fourier transform) method. i H a j=0, i, j = 0, ..., N A -1, i≠j, a i It can be calculated from the DFT matrix:

[0056]

[0057] Where λ is the carrier wavelength, N A is the number of array elements of Alice’s antenna, and d is the array element spacing. is the orthogonal direction of the i-th codebook.

[0058] It can be understood that the DFT matrix itself has row-column orthogonality, so we only need to make If the coefficients in the DFT matrix are satisfied, a codebook orthogonal in all directions can be generated. i The design ideas differ in terms of pattern orthogonality, antenna power allocation, etc., which in turn affects the correlation of channels between users at different locations.

[0059] Step S202: the legitimate sender calculates a steering matrix according to the spatial position of the legitimate receiver;

[0060] Specifically, since the legitimate receiver Bob will not be exactly in the orthogonal direction of a codebook i Therefore, the legitimate sender Alice needs to calculate the steering matrix S according to the spatial position of the legitimate receiver Bob, so as to 0 Angle adjustment is performed to obtain the precoding matrix W.

[0061] The steering matrix S is calculated as follows:

[0062]

[0063]

[0064] Among them, θ S Indicates the steering angle, represents the angle of the antenna element of the legitimate sender Alice, θ B Indicates the spatial location of the legal receiver Bob.

[0065] Step S203: the legitimate sender generates a random perturbation vector, and obtains an anisotropic beam according to the orthogonal beam matrix and the random perturbation vector;

[0066] Specifically, since the legitimate sender Alice is equipped with N A antennas, so Alice needs to use a random number generator to get a length of N A The random perturbation vector The purpose is to randomly scramble the channel, R can be expressed as follows:

[0067]

[0068] Among them, the random perturbation vector R follows a complex Gaussian distribution, σ l represents the standard deviation, and r i Any two random variables in are independent of each other.

[0069] Specifically, according to the orthogonal beam matrix A and the random perturbation vector R, the anisotropic beam W can be obtained: 0 , satisfying the following relationship:

[0070]

[0071] Step S204: The legitimate sender obtains a precoding matrix according to the anisotropic beam and the steering matrix;

[0072] Specifically, the legitimate sender Alice obtains the anisotropic beam W according to the above steps S202 and S203 0 And the steering matrix S obtains the precoding matrix W.

[0073] The precoding matrix W satisfies the following relationship:

[0074] W=diag(S)W 0

[0075] Among them, the diag function is used to construct a diagonal matrix.

[0076] Specifically, the legitimate sender Alice converts the original channel H into AB Convert to equivalent channel G AB , the legitimate sender Alice can calculate the equivalent channel G AB The channel information is as follows:

[0077] G AB =H AB H W

[0078] Among them, H AB represents the original channel, H AB H Indicates H AB The conjugate of , W represents the precoding matrix.

[0079] It can be understood that the legitimate sender Alice uses the precoding matrix W to convert the original channel H between the legitimate sender Alice and the legitimate receiver Bob into AB Convert to equivalent channel G AB , at this time, the channel H between the legitimate sender Alice and the simulated eavesdropper EveAE Can be converted to G AE =H AE H W. Since the legitimate sender Alice designs the precoding matrix W based on the spatial position of the legitimate receiver Bob, the newly constructed Alice-Bob equivalent channel G AB and Alice-Eve channel G AE The difference increases and the correlation decreases, so the simulated eavesdropper Eve cannot observe H AE or G AE Get the communication channel G between the legitimate sender Alice and the legitimate receiver Bob AB information.

[0080] Step S3: The legitimate sender performs precoding processing on the pilot signal according to the precoding matrix, and sends the precoded signal to the legitimate receiver.

[0081] Specifically, the precoding matrix is ​​used to change the spatial characteristics of the transmitted signal, so that the channel response observed by the legitimate receiver will also change. The legitimate sender Alice precodes the pilot signal according to the precoding matrix W and sends the precoded signal to the legitimate receiver Bob;

[0082] It can be understood that the pilot signal before precoding processing can be consistent with the pilot signal sent by the legitimate receiver in step S1, or it can be a newly designed pilot signal. The purpose is to send it to the legitimate receiver Bob after precoding processing, so that the subsequent legitimate receiver Bob can perform channel estimation based on the received signal.

[0083] Step S4: The legal receiver receives the precoded signal from the legal sender, performs channel estimation based on the received signal, and obtains an equivalent channel.

[0084] Specifically, the legitimate receiver Bob receives the precoded signal from the legitimate sender Alice, and performs channel estimation based on the received signal to obtain the equivalent channel Channel estimation methods include common algorithms such as least squares and minimum mean square error.

[0085] It can be understood that after the precoding matrix performs precoding processing on the pilot signal, the original channel is no longer applicable, so the legal receiver needs to re-estimate the channel according to the new pilot signal to update the original channel to an equivalent channel.

[0086] Furthermore, if we need to further increase the Alice-Bob equivalent channel G AB and Alice-Eve channel G AEIf the difference is not found and the consumed time is less than the channel coherence time T, the cycle can be repeated from step S203. If the consumed time is greater than the channel coherence time T, it is necessary to start again from step S1.

[0087] It can be understood that when the cycle is repeated from step S203, the equivalent channel G AB The original channel H AB , forming a new equivalent channel G in the subsequent cycle steps AB .

[0088] On the basis of the above embodiments, an embodiment of the present invention further provides a key generation method for wireless channel decorrelation based on spatial position, comprising:

[0089] The two legal communicating parties obtain their respective equivalent channels based on the above wireless channel decorrelation method;

[0090] Specifically, the legitimate sender Alice uses the precoding matrix W and the original channel H AB Calculate the equivalent channel G AB , the legitimate receiver Bob estimates the channel based on the pilot signal sent by the legitimate sender and obtains the equivalent channel

[0091] The two parties in legitimate communication generate keys based on their respective equivalent channels.

[0092] Specifically, since the precoding matrix W is designed based on the spatial position of the legitimate receiver Bob, the channel G AE With the equivalent channel G AB Between AE With the equivalent channel G AB There is no correlation between them, which results in Eve being unable to obtain AE or H AE Get the equivalent channel G AB Therefore, Alice and Bob can AB and As a key source, it is used to generate keys, which improves the security of key generation.

[0093] Figure 3 An example of a physical structure diagram of an electronic device is provided, and the electronic device may include: a processor 301, a communication interface 302, a memory 303, and a communication bus 304, wherein the processor 301, the communication interface 302, and the memory 303 communicate with each other through the communication bus 304. The processor 301 may call the logic instructions in the memory 303 to execute the method in the above embodiment, and the method includes:

[0094] The legal sender estimates the original channel and the spatial position of the legal receiver based on the pilot signal sent by the legal receiver; the legal sender designs a precoding matrix based on the spatial position of the legal receiver, and converts the original channel into an equivalent channel based on the precoding matrix; the legal sender precodes the pilot signal according to the precoding matrix, and sends the precoded signal to the legal receiver; the legal receiver receives the precoded signal from the legal sender, estimates the channel based on the received signal, and obtains the equivalent channel.

[0095] In addition, when the logic instructions in the above-mentioned memory 303 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0096] The embodiment of the present invention further provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, when the program instructions are executed by a computer, the computer can perform the methods provided by the above-mentioned method embodiments, for example, including:

[0097] The legal sender estimates the original channel and the spatial position of the legal receiver based on the pilot signal sent by the legal receiver; the legal sender designs a precoding matrix based on the spatial position of the legal receiver, and converts the original channel into an equivalent channel based on the precoding matrix; the legal sender precodes the pilot signal according to the precoding matrix, and sends the precoded signal to the legal receiver; the legal receiver receives the precoded signal from the legal sender, estimates the channel based on the received signal, and obtains the equivalent channel.

[0098] An embodiment of the present invention further provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the methods provided by the above method embodiments are implemented, for example, including:

[0099] The legal sender estimates the original channel and the spatial position of the legal receiver based on the pilot signal sent by the legal receiver; the legal sender designs a precoding matrix based on the spatial position of the legal receiver, and converts the original channel into an equivalent channel based on the precoding matrix; the legal sender precodes the pilot signal according to the precoding matrix, and sends the precoded signal to the legal receiver; the legal receiver receives the precoded signal from the legal sender, estimates the channel based on the received signal, and obtains the equivalent channel.

[0100] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wireless channel decorrelation method based on spatial position, characterized in that: include: Step S1: The legitimate sender estimates the original channel and the spatial position of the legitimate receiver based on the pilot signal sent by the legitimate receiver; Step S2: the legal sender designs a precoding matrix according to the spatial position of the legal receiver, and converts the original channel into an equivalent channel according to the precoding matrix; Step S3: the legitimate sender performs precoding processing on the pilot signal according to the precoding matrix, and sends the precoded signal to the legitimate receiver; Step S4: The legal receiver receives the precoded signal from the legal sender, performs channel estimation based on the received signal, and obtains an equivalent channel.

2. The wireless channel decorrelation method based on spatial position according to claim 1, characterized in that: The legal sender in step S2 designs a precoding matrix according to the spatial position of the legal receiver, including: Step S201: the legitimate sender adopts an orthogonal beam design method to obtain an orthogonal beam matrix; Step S202: the legal sender calculates a steering matrix according to the spatial position of the legal receiver; Step S203: the legitimate sender generates a random perturbation vector, and obtains an anisotropic beam according to the orthogonal beam matrix and the random perturbation vector; Step S204: The legitimate sender obtains a precoding matrix according to the anisotropic beam and the steering matrix.

3. The wireless channel decorrelation method based on spatial position according to claim 2, characterized in that: In step S201, the orthogonal beam matrix is ​​expressed as follows: Among them, N A Indicates the number of array elements of the legal transmitter antenna, a i represents the first i∈0,1,…,N A -1 direction codebook, satisfying a i H a j =0,i,j=0,...,N A -1, i≠j.

4. The method for decorrelation of wireless channels based on spatial position according to claim 2, characterized in that: The random disturbance vector in step S203 follows a complex Gaussian distribution, which is expressed as follows: Where R represents the random perturbation vector, N A Indicates the number of array elements of the legal transmitter antenna, σ l represents the standard deviation, and r i Any two random variables in are independent of each other.

5. The method for decorrelation of wireless channels based on spatial position according to claim 2, characterized in that: In step S203, the anisotropic beam satisfies the following relationship: <h2 style=";text-align:left;direction:ltr">W<h2 style=";text-align:left;direction:ltr"> 0 <h2 style=";text-align:left;direction:ltr"> =AR Among them, W 0 represents anisotropic beam, A represents orthogonal beam matrix, and R represents random perturbation vector.

6. The method for decorrelation of wireless channels based on spatial position according to claim 2, characterized in that: In step S204, the precoding matrix satisfies the following relationship: W=diag(S)W 0 Where W represents the precoding matrix, S represents the steering matrix, and the diag function is used to construct a diagonal matrix. 0 represents an anisotropic beam.

7. The method for decorrelation of wireless channels based on spatial position according to claim 1, characterized in that: In step S2, the equivalent channel calculation formula is as follows: G AB =H AB H W Among them, G AB represents the equivalent channel, H AB represents the original channel, H AB H Indicates H AB The conjugate of , W represents the precoding matrix.

8. A key generation method based on wireless channel decorrelation based on spatial position, characterized in that: include: The two legal communicating parties obtain their respective equivalent channels based on the method described in any one of claims 1 to 7; The two parties in legitimate communication generate keys based on their respective equivalent channels.

9. A communication device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 8 when executing the program.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

Images