A physical layer security waveform generation method

Abstract

The application discloses a physical layer security waveform generation method, comprising the following steps: step 1, obtaining and constructing a symbol-related prime set and a chip-related prime set; step 2, processing the symbol-related prime set and the chip-related prime set respectively to obtain a symbol vector and a chip vector; step 3, performing point multiplication operation on the symbol vector and the chip vector to obtain a signal vector; step 4, filtering the signal vector as an input through a baseband shaping filter; and step 5, moving the filtered result to a corresponding frequency point through a quadrature modulator to obtain a final result. The method obtains the concealment characteristics of the waveform and the security characteristics of the transmission information based on randomization time-varying physical layer waveform parameters, and can obtain a short-time stable data transmission rate, thereby meeting the actual requirements of a wireless communication system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a method for waveform encryption of transmission information in the physical layer of a communication protocol, and more particularly to a physical layer security waveform generation method. BACKGROUND

[0002] The rapid development of wireless communication technology has put forward higher requirements for the security of wireless communication systems. On the one hand, the broadcast nature of wireless channels makes wireless transmission more vulnerable to illegal interception or attack. On the other hand, existing application layer encryption techniques based on keys cannot cope with new attacks on the wireless physical layer, such as signal capture, feature extraction, electromagnetic interference, etc. Therefore, how to design a more secure communication method according to the characteristics of wireless communication has become a problem to be solved for future wireless communication systems.

[0003] An important indicator for measuring the performance of a communication system is security. Whether the information transmission of a communication system can be reliably and securely protected is a necessary condition for the existence and application of this communication system. Secure communication mainly refers to the confidentiality of data transmission, which can prevent data from being stolen. Specifically, the security of a communication system mainly includes two aspects. On the one hand, it is necessary to ensure that legitimate users can communicate normally and reliably. On the other hand, it is necessary to ensure that the communication information between legitimate users cannot be stolen by illegal users.

[0004] Wireless communication systems face more serious security threats and risks than traditional wired communication systems due to their inherent characteristics, which are manifested in the following aspects:

[0005] 1) The openness of wireless communication channels makes wireless communication systems more vulnerable to attacks by malicious users.

[0006] The openness of wireless channels makes wireless channels a natural broadcast channel, which means that wireless channels do not have the clear defense boundaries that wired channels have. Therefore, wireless communication systems do not have the firewall or gateway protection technology that exists in wired communication systems. In a wireless communication system, there may be illegal users within the coverage area of the wireless signal, so it is natural for information transmitted on the wireless channel to be eavesdropped by unauthorized illegal users, or even actively attacked by malicious users.

[0007] 2) The mobility of terminal devices in wireless communication systems increases the difficulty of security management.

[0008] In wired communication system, the user terminal is connected with the access device through cable, so the position of the user terminal will not move widely, and the security management of the user terminal is also relatively easy. However, the wireless communication terminal can move at any time and anywhere, which makes the topology of the wireless network always in dynamic change, which means that the wireless communication terminal cannot be provided with reliable physical protection, which makes the probability of wireless communication information being hijacked and eavesdropped larger. In addition, the wireless channel also has the characteristics of time-varying and fading, which brings great instability to the wireless signal, which also increases the difficulty of security management of the wireless communication system from the objective point of view.

[0009] 3) The wireless communication terminal has weak computing processing capability, so it cannot use too complex security protection technology.

[0010] In wired communication system, the user terminal usually has strong computing capability, so the user terminal can prevent eavesdropping and attack by using an algorithm with high complexity and security coefficient to realize secure communication. However, in wireless communication system, due to the limitation of computing capability, battery capacity and volume of the mobile terminal, the encryption algorithm which is too complex in wired communication system is difficult to apply to wireless communication system. Therefore, it is necessary to study the suitable security technology and method for wireless communication system according to the actual characteristics of wireless terminal, which also puts forward higher requirements for the security communication theory of wireless communication system.

[0011] Today, the security of wireless communication system is paid more and more attention, and the corresponding security technology is added to each layer of the network protocol stack of the system, which has become a necessary means to realize secure and reliable communication. However, in the process of continuous development and progress of various security mechanisms in the upper layer of the network protocol stack, the security protection mechanism of the physical layer at the bottom of the network protocol stack has been ignored by people. SUMMARY

[0012] The purpose of the present application is to overcome the shortcomings of the prior art, and a physical layer security waveform generation method is proposed, which obtains the concealment characteristics of the waveform and the security characteristics of the transmission information based on randomization of time-varying physical layer waveform parameters, and can obtain short-time stable data transmission rate, which meets the actual needs of wireless communication system. The randomization of time-varying physical layer waveform parameters includes periodic parameters existing in the usual waveform, and the periodic components in the modulated signal are eliminated by randomizing these parameters to obtain the anti-interception characteristics of the physical layer waveform.

[0013] In order to solve the above technical problems, the technical scheme of the present application is as follows:

[0014] A physical layer security waveform generation method, comprising the following steps:

[0015] Step 1, obtaining and constructing symbol related prime set and chip related prime set;

[0016] Step 2, processing symbol related prime set and chip related prime set respectively to obtain symbol vector and chip vector;

[0017] The processing method of the symbol related prime set comprises calculating symbol related codebook base vector, performing interleaving operation on the symbol related codebook base vector, constructing symbol transformation matrix, and applying the symbol transformation matrix to pre-process the initial symbol vector to be transmitted;

[0018] The processing method of the chip related prime set comprises calculating chip related codebook base vector, constructing chip related codebook vector, interleaving the chip related codebook vector, constructing pseudo-random base complex sequence, and pre-processing the pseudo-random base sequence vector;

[0019] Step 3, performing dot product operation on the symbol vector and the chip vector to obtain signal vector;

[0020] Step 4, filtering the signal vector as input through a baseband shaping filter;

[0021] Step 5, moving the filtered result to the corresponding frequency point through a quadrature modulator to obtain the final result.

[0022] As preferred, in the step 1, the method for constructing the symbol related prime set is:

[0023] Firstly, the size M of the symbol related prime set is determined s , and the symbol related prime set is represented as wherein is an arbitrary prime number and satisfies The symbol permutation matrix T is defined s , and the size is M s ×M s , the elements on the sub-diagonal line are 1, and the other elements are 0; the number of symbols that can be transmitted in a message period is and the time occupied is wherein SF Base is the basic spreading factor, and τ c is the chip period;

[0024] The method for constructing the codebook related prime set is:

[0025] Firstly, the size M of the chip related prime set is determined c , and the chip related prime set is represented as wherein is a prime number and satisfies The permutation matrix T is defined c , and the size is M c ×Mc with 1 on the sub-diagonal and 0 elsewhere.

[0026] As preferred, in the step 1, the method of constructing the codebook-related prime number set is:

[0027] First, determine the size M of the code-chip related prime number set c The code-chip related prime number set is represented as wherein is a prime number and satisfies Define the permutation matrix T c with size M c ×M c with 1 on the sub-diagonal and 0 elsewhere.

[0028] As preferred, in the step 2, the method of calculating the symbol-related codebook basis vector is:

[0029] Calculate the symbol-related codebook basis vector wherein

[0030] wherein i is the index of the i-th element in the vector, k is the index of the summation operation, and is the j-th element in the symbol-related prime number set.

[0031] As preferred, in the step 2, construct the symbol transformation matrix G s with size P s T(P s ) T SF Base ×K s The element G s (i,j) in the symbol transformation matrix G s can be represented as:

[0032]

[0033] wherein is the related codebook basis vector after interleaving;

[0034] Apply the transformation matrix G s to the initial symbol vector S to be sent for preprocessing:

[0035] Q s =G s S T

[0036] Obtain the preprocessed symbol vector Q s with size 1×P s T(P s ) TSF Base .

[0037] As a preference, in step 2, the chip-related codebook basis vector is calculated wherein

[0038] The repetition parameter is calculated:

[0039]

[0040] wherein T s and T c are a symbol permutation matrix and a chip permutation matrix, respectively, SF Base is a basic spreading factor;

[0041] Finally, the chip-related codebook vector is constructed according to the chip-related codebook basis vector and the repetition parameter

[0042] As a preference, in step 2, the chip transformation matrix G c is constructed, which has a size of P s T(P s ) T SF Base × RK c The element G c (i,j) in the chip transformation matrix G c may be represented as:

[0043]

[0044] wherein, is a relevant codebook basis vector obtained by performing an interleaving operation on the chip-related codebook vector V c .

[0045] As a preference, in step 2, the pseudo-random basis complex sequence is constructed n = 1, 2, … RK c , and a pseudo-random basis sequence vector is obtained Finally, the chip transformation matrix G c is applied to the pseudo-random basis sequence vector for preprocessing:

[0046] Q c = G c C T

[0047] A preprocessed chip vector Q c is obtained, which has a size of 1 × P s T(P s ) T SF Base .

[0048] As preferred, in the step 2, the interleaving operation adopts any one of a group interleaver, a pseudo-random matrix cyclic shift interleaver, a co-prime interleaver and a random interleaver.

[0049] The present application has the following features and advantages:

[0050] By using the above technical solution, the physical layer security waveform design method of the present application obtains the information security characteristics of the physical layer transmission by discretizing and non-stationarizing the physical layer waveform parameters, and the specific effects include:

[0051] The present application disturbs the physical layer waveform parameters by using a multi-dimensional pseudo-random sequence, and converts the stationary periodic component parameters in the physical layer waveform into short-time stationary parameters. This greatly reduces the interception probability of the waveform, and the non-cooperative party cannot determine the frequency point and other information used in the communication, so that the non-cooperative party cannot complete the interception of the waveform.

[0052] The present application disturbs the physical layer waveform parameters by using a multi-dimensional pseudo-random sequence, and converts the stationary periodic component parameters in the physical layer waveform into short-time stationary parameters. This greatly reduces the interception probability of the waveform, and the non-cooperative party cannot determine the frequency point and other information used in the communication, so that the non-cooperative party cannot complete the interception of the waveform.

[0053] The physical layer security technology based on the physical layer characteristics of the wireless communication channel is a protocol stack bottom layer technology for ensuring the security of the wireless communication system. By cooperating with and complementing the key encryption technology on the upper layer of the network protocol stack, a more three-dimensional information security protection system can be constructed, so that the communication can be more securely and effectively realized in the wireless communication system, and the present application has important theoretical significance and practical value. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0055] Figure 1 The flowchart of the physical layer security waveform generation method in the embodiments of the present application is shown.

[0056] Figure 2 The simulation result diagram of the anti-interference performance of the embodiments of the present application is shown.

[0057] Figure 3 The simulation result diagram of the anti-interference performance of the existing OFDM system is shown. DETAILED DESCRIPTION

[0058] It should be noted that the embodiments and features in the present application can be combined with each other without conflict.

[0059] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0060] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0061] The present application provides a physical layer security waveform generation method, as shown in Figure 1 , comprising the following steps:

[0062] Step 1, obtaining and constructing a symbol-related prime set and a chip-related prime set.

[0063] Specifically, for the construction of the symbol-related prime set: determine the size M s of the symbol-related prime set, and the symbol-related prime set is represented as wherein takes any prime number and satisfies Define the symbol permutation matrix T s , the size is M s ×M s , the elements on the sub-diagonal line are 1, and the remaining elements are 0. The number of symbols that can be transmitted in a message period , and the time occupied is wherein SFBase is a basic spreading factor, τ c is a chip period;

[0064] For construction of the chip-related prime set: determine the size M of the chip-related prime set c , the chip-related prime set is represented as wherein is a prime number and satisfies define the permutation matrix T c , the size is M c ×M c , the elements on the sub-diagonal are 1, and the remaining elements are 0.

[0065] It should be noted that the symbol refers to the symbol after modulation, which is obtained by modulating the binary information bits through modulation methods such as BPSK, QPSK, etc. The symbol of the spread spectrum sequence used for spread spectrum is called a chip.

[0066] The symbol-related prime set refers to the symbol period-related prime set, that is, the set of values that the symbol period can take.

[0067] Similarly, the chip-related prime set refers to the chip period-related prime set, that is, the set of values that the chip period can take.

[0068] Step 2, respectively, the symbol-related prime set and the chip-related prime set are processed to obtain the symbol vector and the chip vector.

[0069] Specifically, the processing method of the symbol-related prime set is as follows:

[0070] First, calculate the symbol-related codebook base vector wherein,

[0071] wherein, i is the index of the i-th element in the vector, k is the index of the summation operation, and is the j-th element in the symbol-related prime set.

[0072] Next, the symbol-related codebook base vector V s is subjected to interleaving operation, wherein the interleaving operation adopts any one of a group interleaver, a pseudo-random matrix cyclic shift interleaver, a co-prime interleaver, and a random interleaver.

[0073] Further, in the embodiment, the symbol-related codebook base vector V s is subjected to interleaving operation, and each element in V is processed as follows:

[0074]

[0075] Obtain the interleaved related codebook basis vector in (d x ,d y ,d z ) is a finite-length discrete multi-scroll chaotic sequence Sort in ascending order to obtain a sorted finite length chaotic sequence Then, a multi-dimensional random index sequence is formed according to the position index values ​​of the sorted sequence values ​​in the original sequence.

[0076] Furthermore, in this embodiment, the symbol transformation matrix G is constructed based on the minimum criterion of the randomized symbol period mean in order to maximize the symbol period time resolution capability. s , whose size is P s T(P s ) T SF Base ×K s . Symbol transformation matrix G s The element G in s (i,j) can be expressed as:

[0077]

[0078] Send symbol vector Perform preprocessing:

[0079] Q s =G s S T

[0080] Get the preprocessed symbol vector Q s , whose size is 1×P s T(P s ) T SF Base .

[0081] The processing method for the chip-related prime number set is as follows:

[0082] Calculate the chip-related codebook basis vector in

[0083] Calculate the repetition parameter Constructing chip-related codebook vector Where T s and T c are symbol permutation matrix and chip permutation matrix respectively, SF Base is the basic expansion factor.

[0084] The chip-related codebook vector V c Perform interleaving operations on Each element v in c,k Do the following processing:

[0085]

[0086] Obtain the interleaved related codebook basis vector in

[0087] Similarly, in this embodiment, the chip transformation matrix G is constructed based on the minimum criterion of the randomized chip period mean in order to maximize the time resolution of the chip period. c , whose size is P s T(P s ) T SF Base ×RK c , chip transformation matrix G c The element G in c (i,j) can be expressed as:

[0088]

[0089] Computes a pseudorandom base complex number sequence n=1,2,…RK c , for pseudo-random basis sequence vector Perform preprocessing:

[0090] Q c =G c C T

[0091] Get the preprocessed chip vector Q c , whose size is 1×P s T(P s ) T SF Base .

[0092] It should be noted that, in this embodiment, during the interleaving operation, a discrete multi-scroll chaotic sequence (x, y, z) needs to be generated, and the specific steps are as follows:

[0093] (1) Generate a random number α between 0 and 1, satisfying α∈[0,1];

[0094] (2) Calculate the generation parameter β of the multi-scroll chaotic system, namely:

[0095] β=0.47+0.49*α

[0096] (3) generating a discrete multi-scroll chaotic sequence (x, y, z), the multi-scroll chaotic sequence being generated according to the following formula:

[0097]

[0098] The function f(x) is defined as:

[0099]

[0100] wherein sgn(·) is a sign function, the value of Δ is a real constant, M is a positive integer, γ is a discrete sequence time interval constant, and generally can take a value of 0.01, and (x0, y0, z0) can take a value of (0.15, -0.23, 0.12).

[0101] (4) converting the discrete multi-scroll chaotic sequence (x, y, z) to a binary field, that is, obtaining a pseudo-random sequence on a 0 / 1 binary field through the following algorithm:

[0102]

[0103] wherein represents the e-th digit of the decimal part of z i in a double-precision representation. According to the same method, similar operations are performed on the sequences x and y to obtain the sequences x' and y' mapped to the binary field.

[0104] Step 3, performing a dot product operation on the sign vector and the chip vector to obtain a signal vector as an input vector of a baseband shaping filter, and the expression is as follows:

[0105] Q tx = Q s .*Q c

[0106] The operator (.) represents a dot product operation of vectors, that is, the corresponding elements of the vectors on the left and right sides of the operator are multiplied.

[0107] Step 4, filtering the signal vector as an input through a baseband shaping filter;

[0108] Step 5, moving the filtered result to a corresponding frequency point through a quadrature modulator to obtain a final result.

[0109] Simulation effect comparison

[0110] wherein Figure 2 is the anti-interference performance of the meta waveform system generated by the method of the embodiment of the application, Figure 3The anti-interference performance of the current mainstream 4G / 5G physical layer waveform OFDM system is evaluated. The simulation respectively evaluates the suppression ability of two kinds of waveform systems to narrowband interference and wideband interference. The simulation results show that the current mainstream 4G / 5G physical layer waveform OFDM system is obviously insufficient in the ability to resist wideband interference. When the signal-to-interference ratio SIR is -10 dB, the system error rate of the OFDM system is close to 50%, and the system error rate is mainly caused by interference. When the signal-to-interference ratio SIR is 0 dB and the signal-to-noise ratio SNR is 20 dB, the system error rate of the OFDM system is close to 10%, which is too high for common voice / data services, and will cause information transmission failure. On the other hand, for the waveform system, the working signal-to-noise ratio is much lower than that of the OFDM system, indicating that the waveform system has good covert communication characteristics and can work in a very low received signal power situation. In addition, the waveform system has significant suppression ability to narrowband interference with SIR=-10 dB and wideband interference with SIR=-20 dB, and its error rate is close to that without interference.

[0111] Conclusion: According to the simulation results, the waveform system proposed in the present application has significant advantages in signal anti-interference ability and signal covert communication ability compared with the current mainstream 4G / 5G physical layer waveform OFDM system. This provides an important basis for the wide application of the waveform system in many scenarios.

[0112] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments including components can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for generating a physical layer security waveform, characterized in that: The steps include: Step 1: Obtain and construct a symbol-related prime number set and a chip-related prime number set; The method to construct a set of symbolically related prime numbers is: First, determine the size M of the set of sign-dependent prime numbers s , the set of symbol-related prime numbers is represented as in The value is any prime number and satisfies Define the symbol permutation matrix T s , size M s ×M s , the elements on the sub-diagonal are 1, and the rest are 0; then the number of symbols that can be transmitted in one message cycle is The time it takes is T B =P s T s (P s ) T *SF Base *τ c , where SF Base is the basic expansion factor, τ c is the chip period; The method for constructing the codebook related prime number set is: First, determine the size M of the chip-related prime number set c , the chip-related prime number set is expressed as in is a prime number and satisfies Define the permutation matrix T c , size M c ×M c , the elements on the secondary diagonal are 1, and the rest are 0 Step 2: Process the symbol-related prime number set and the chip-related prime number set respectively to obtain a symbol vector and a chip vector; The method for processing the symbol-related prime number set includes calculating symbol-related codebook basis vectors, performing interleaving operations on the symbol-related codebook basis vectors, constructing a symbol transformation matrix, and applying the symbol transformation matrix to preprocess an initial symbol vector to be sent; The method for calculating the symbol-related codebook basis vector is: Calculate symbol-related codebook basis vectors in, Where i is the index of the i-th element in the vector, k is the index of the sum operation, and is the j-th element in the set of symbolically related prime numbers; Construct symbolic transformation matrix G s , whose size is P s T(P s ) T SF Base ×K s , symbol transformation matrix G s The element G in s (i,j) can be expressed as: in, is the interleaved related codebook basis vector; Apply the transformation matrix G s For the initial symbol vector to be sent Perform preprocessing: Q s =G s S T Get the preprocessed symbol vector Q s , whose size is 1×P s T(P s ) T SF Base ; The processing method of the chip-related prime number set includes calculating chip-related codebook basis vectors, constructing chip-related codebook vectors, interleaving chip-related codebook vectors, constructing a pseudo-random base complex number sequence, and preprocessing the pseudo-random base sequence vectors; Calculate the chip-related codebook basis vector in Calculate the repetition parameter: Where T s and T c are symbol permutation matrix and chip permutation matrix respectively, SF Base is the basic expansion factor; Finally, the chip-related codebook vector is constructed according to the chip-related codebook basis vector and the repetition parameter. Construct the chip transformation matrix G c , whose size is P s T(P s ) T SF Base ×RK c , chip transformation matrix G c The element G in c (i,j) can be expressed as: in, is the chip-related codebook vector V c The relevant codebook basis vectors obtained after the interleaving operation; Computes a pseudorandom base complex number sequence Then we get the pseudo-random basis sequence vector Finally, the chip transformation matrix G is applied c Preprocess the pseudo-random basis sequence vector: Q c =G c C T Get the preprocessed chip vector Q c , whose size is 1×P s T(P s ) T SF Base ; Step 3: Perform a dot product operation on the symbol vector and the chip vector to obtain a signal vector; Step 4: The signal vector is used as input and filtered through a baseband shaping filter; Step 5: Move the filtered result to the corresponding frequency point through the orthogonal modulator to obtain the final result.

2. A method for generating a physical layer security waveform according to claim 1, characterized in that: In the step 2, the interleaving operation adopts any one of a block interleaver, a pseudo-random row-column cyclic shift interleaver, a coprime interleaver and a random interleaver.

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