Physical layer safety waveform generation method

Abstract

The invention discloses a physical layer security waveform generation method. The method comprises the following steps: step 1, acquiring and constructing a symbol related prime number set and a chip related prime number set; 2, respectively processing the symbol related prime number set and the chip related prime number set to obtain a symbol vector and a chip vector; step 3, carrying out point multiplication operation on the symbol vector and the chip vector to obtain a signal vector; step 4, filtering the signal vector as input through a baseband shaping filter; and 5, moving a filtered result to a corresponding frequency point through a quadrature modulator to obtain a final result. According to the method, the concealment characteristic of the waveform and the security characteristic of the transmission information are obtained based on the change of the waveform parameters of the physical layer during randomization, the short-time stable data transmission rate can be obtained, and the actual requirements of a wireless communication system are met.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a method for waveform encryption of transmission information in the physical layer of a communication protocol, specifically to a method for generating a physical layer security waveform. Background Art

[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 characteristics of wireless channels make wireless transmission more vulnerable to illegal interception or attack; on the other hand, the existing key-based application layer encryption technology 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 based on the characteristics of wireless communication has become an urgent problem to be solved in future wireless communication systems.

[0003] Security is an important indicator for measuring the performance of a communication system. Whether the information transmission of a communication system can be reliably protected is a necessary condition for the existence and application of the communication system. Secure communication mainly refers to the confidentiality of data transmission and the prevention of data theft. 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, and on the other hand, it is necessary to ensure that the communication information between legitimate users cannot be stolen by illegal users.

[0004] Due to some inherent characteristics, wireless communication systems face more serious security threats and hidden dangers than traditional wired communication systems, which are specifically manifested in the following aspects:

[0005] 1) Due to the open nature of wireless communication channels, wireless communication systems are more vulnerable to attacks by malicious users.

[0006] The openness of wireless channels makes them natural broadcast channels, which means that wireless channels cannot have clear defense boundaries like wired channels. Therefore, wireless communication systems do not have the protection technologies such as firewalls or gateways that exist in wired communication systems. In wireless communication systems, as long as they are within the coverage area of ​​wireless signals, there may be illegal users. Therefore, information transmitted on wireless channels is naturally easy to be silently 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 their security management.

[0008] In wired communication systems, since user terminals are connected to access devices through cables, the location of user terminals will not move over a large range, so their security management is relatively easy. However, since wireless communication terminals can move anywhere at any time, the topology of the wireless network is always in dynamic change, which means that it is impossible to provide reliable physical protection for wireless communication terminals, which increases the probability of wireless communication information being hijacked and eavesdropped. In addition, wireless channels also have characteristics such as time variation and fading, which bring great instability to wireless signals. Objectively, this also increases the difficulty of security management of wireless communication systems.

[0009] 3) Due to the weak computing and processing capabilities of wireless communication terminals, they are unable to adopt overly complex security protection technologies.

[0010] In wired communication systems, user terminals usually have strong computing power, so that user terminals can prevent eavesdropping and attacks by using algorithms with high complexity and security factors to achieve secure communication. However, in wireless communication systems, due to the limitations of mobile terminals in computing power, battery capacity, volume, etc., overly complex encryption algorithms in wired communication systems are difficult to apply to wireless communication systems. Therefore, it is necessary to study suitable security technologies and methods for wireless communication systems based on the actual characteristics of wireless terminals, which also puts higher requirements on the secure communication theory of wireless communication systems.

[0011] Today, the security of wireless communication systems is becoming more and more important. The addition of corresponding security technologies to each layer of the system's network protocol stack has become a necessary means to achieve secure and reliable communications. However, as various security mechanisms in the upper layers of the network protocol stack, such as cryptography, continue to develop and progress, the physical layer security protection mechanism at the bottom of the network protocol stack has been ignored. Summary of the invention

[0012] The purpose of the present invention is to address the deficiencies of the prior art and propose a method for generating a physical layer security waveform. The method obtains the concealment characteristics of the waveform and the security characteristics of the transmitted information based on randomized time-varying physical layer waveform parameters, and can obtain a short-term stable data transmission rate, meeting the actual needs of the wireless communication system. The above-mentioned randomized time-varying physical layer waveform parameters include periodic parameters existing in the usual waveform. By randomizing these parameters, the periodic components in the modulated signal are eliminated, and the anti-interception characteristics of the physical layer waveform are obtained.

[0013] In order to solve the above technical problems, the technical solution of the present invention is:

[0014] A method for generating a physical layer security waveform comprises the following steps:

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

[0016] Step 2: respectively process the symbol-related prime number set and the chip-related prime number set to obtain a symbol vector and a chip vector;

[0017] 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 the initial symbol vector to be sent;

[0018] 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 sequence, and preprocessing the pseudo-random base sequence vectors;

[0019] Step 3: Perform a dot multiplication operation on the symbol vector and the chip vector to obtain a signal vector;

[0020] Step 4: Using the signal vector as input and filtering it through a baseband shaping filter;

[0021] Step 5: Move the filtered result to the corresponding frequency point through the orthogonal modulator to obtain the final result.

[0022] Preferably, in step 1, the method for constructing a set of symbol-related prime numbers is:

[0023] First, determine the size M of the set of sign-dependent prime numbers s , the set of symbol-related prime numbers is represented by in The value can be any prime number and satisfy 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 Among them SF Base is the basic expansion factor, τ c is the chip period;

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

[0025] 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 ×Mc , the elements on the secondary diagonal are 1, and the rest are 0.

[0026] Preferably, in step 1, the method for constructing a codebook-related prime number set is:

[0027] First, determine the size M of the chip-related prime number set c , the set of chip-related prime numbers 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.

[0028] Preferably, in step 2, the method for calculating the symbol-related codebook basis vector is:

[0029] Calculate the symbol-related codebook basis vector in,

[0030] 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 sign-dependent primes.

[0031] Preferably, in step 2, a symbol transformation matrix G is constructed. 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:

[0032]

[0033] in, is the interleaved related codebook basis vector;

[0034] Apply the transformation matrix G s For the initial symbol vector to be sent Preprocessing:

[0035] Q s =G s S T

[0036] Get the preprocessed symbol vector Q s , whose size is 1×P s T(P s ) TSF Base .

[0037] Preferably, in step 2, the chip-related codebook basis vector is calculated in

[0038] Calculate the repetition parameter:

[0039]

[0040] Where T s and T c are symbol permutation matrix and chip permutation matrix respectively, SF Base is the basic expansion factor;

[0041] Finally, the chip-related codebook vector is constructed based on the chip-related codebook basis vector and the repetition parameter.

[0042] Preferably, in step 2, a chip transformation matrix G is constructed. 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:

[0043]

[0044] in, is the chip-related codebook vector V c The relevant codebook basis vectors are obtained after the interleaving operation.

[0045] Preferably, in step 2, a pseudo-random base complex sequence is constructed and calculated. n=1,2,…RK c , and then get the pseudo-random basis sequence vector Finally, the chip transformation matrix G is applied c Preprocess the pseudo-random basis sequence vector:

[0046] Q c =G c C T

[0047] Get the preprocessed chip vector Q c , whose size is 1×P s T(P s ) T SF Base .

[0048] Preferably, in 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.

[0049] The present invention has the following characteristics and beneficial effects:

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

[0051] The present invention perturbs the physical layer waveform parameters through a multi-dimensional pseudo-random sequence, and converts the stationary period 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, resulting in the non-cooperative party being unable to complete the interception of the waveform.

[0052] The present invention randomly interweaves waveform parameters through a multi-dimensional pseudo-random sequence, and different communication transceivers and links use different waveform parameter random interweaving patterns. When a non-cooperative party decodes information transmitted in a legitimate communication link, it cannot steal the transmitted information because it cannot obtain the waveform parameter random interweaving pattern.

[0053] Physical layer security technology based on the physical layer characteristics of wireless communication channels is a protocol stack bottom-level technology that ensures the security of wireless communication systems. By cooperating and complementing with the key encryption technology on the upper layer of the network protocol stack, a more three-dimensional information security protection system can be built, thereby achieving more secure and effective communication in wireless communication systems. It has important theoretical significance and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0055] Figure 1 The figure is a flow chart of a method for generating a physical layer security waveform in an embodiment of the present invention.

[0056] Figure 2 Schematic diagram of the simulation results of the anti-interference performance of an embodiment of the present invention.

[0057] Figure 3 This is a schematic diagram of the simulation results of the anti-interference performance of the existing OFDM system. DETAILED DESCRIPTION

[0058] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0061] The present invention provides a method for generating a physical layer security waveform. Figure 1 As shown, the following steps are included:

[0062] Step 1: Obtain and construct a symbol-related prime number set and a chip-related prime number set.

[0063] Specifically, for the construction of the symbol-related prime number set: determine the size M of the symbol-related prime number set s , the set of symbol-related prime numbers is represented by in The value can be any prime number and satisfy 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 Among them SFBase is the basic expansion factor, τ c is the chip period;

[0064] For the construction of the chip-related prime number set: 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.

[0065] It should be noted that a symbol refers to a modulated code element, which is obtained by modulating a binary information bit through a modulation method such as BPSK, QPSK, etc. The code element of a spread spectrum sequence used for spectrum spreading is called a chip.

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

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

[0068] 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.

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

[0070] First, the symbol-related codebook basis vectors are calculated in,

[0071] 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 sign-dependent primes.

[0072] Then, the symbol-related codebook basis vector V s An interleaving operation is performed, wherein 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.

[0073] Furthermore, in this embodiment, the symbol-related codebook basis vector V s Perform interleaving operations on Each element in Do the following processing:

[0074]

[0075] Get the interleaved related codebook basis vector in (d x ,d y ,d z ) is a finite-length discrete multi-scroll chaotic sequence Sort them in ascending order to get the 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 . The symbol transformation matrix G s The element G in s (i,j) can be expressed as:

[0077]

[0078] Send symbol vector 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 Construct 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] Get the interleaved related codebook basis vector in

[0087] Similarly, in this embodiment, the chip transformation matrix G is constructed based on the minimum mean criterion of the randomized chip period 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 base sequence vector 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, that is:

[0095] β=0.47+0.49*α

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

[0097]

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

[0099]

[0100] Among them, sgn(·) is the sign function, the value of Δ is a real constant, M is a positive integer, and γ is the discrete sequence time interval constant, which can generally be taken as 0.01. 0 ,y 0 ,z 0 )=(0.15,-0.23,0.12).

[0101] (4) The discrete multi-scroll chaotic sequence (x, y, z) is converted to the binary domain, that is, a pseudo-random sequence on the 0 / 1 binary domain is obtained by the following algorithm:

[0102]

[0103] in, represents z in double precision i In the same way, by performing similar operations on sequences x and y, we can obtain sequences x' and y' mapped to the binary domain.

[0104] Step 3: Perform a dot multiplication operation on the symbol vector and the chip vector to obtain a signal vector as the input vector of the baseband shaping filter. The expression is as follows:

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

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

[0107] Step 4: Using the signal vector as input and filtering it through a baseband shaping filter;

[0108] Step 5: Move the filtered result to the corresponding frequency point through the orthogonal modulator to obtain the final result.

[0109] Simulation effect comparison

[0110] in, Figure 2 The anti-interference performance of the meta-waveform system generated by the method of the embodiment of the present invention, Figure 3The anti-interference performance of the current mainstream OFDM system based on the 4G / 5G physical layer waveform. The simulation evaluates the suppression capabilities of the two waveform systems against co-frequency narrowband interference and co-frequency broadband interference. It can be seen from the simulation results that the current mainstream OFDM system based on the 4G / 5G physical layer waveform is obviously insufficient in its ability to resist co-frequency broadband interference. When the OFDM system has a signal-to-interference ratio SIR = -10dB, the system bit error rate is close to 50%, and the bit error rate in the system is mainly caused by interference. When the OFDM system has a signal-to-interference ratio SIR = 0dB and a signal-to-noise ratio SNR = 20dB, the system bit error rate is close to 10%. For common voice / data services, the bit error rate is too high and will lead to information transmission failure. On the other hand, for the proposed waveform system, its working signal-to-noise ratio is much lower than that of the OFDM system, indicating that the meta-waveform system has good covert communication characteristics and can work under extremely low received signal power conditions. In addition, the meta-waveform system has a significant suppression capability for narrowband interference with SIR = -10dB and broadband interference with SIR = -20dB, and its bit error rate is close to that without interference.

[0111] Conclusion: From the simulation results, it can be seen that the waveform system proposed in this invention has significant advantages in signal anti-interference ability and signal covert communication ability compared with the current mainstream OFDM system based on 4G / 5G physical layer waveform. This provides an important basis for the wide application of this waveform system in many scenarios.

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

Claims

1. A method for generating a physical layer security waveform, characterized in that: The steps include: Step 1, obtaining and constructing a symbol-related prime number set and a chip-related prime number set; Step 2: respectively process the symbol-related prime number set and the chip-related prime number set 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 the initial symbol vector to be sent; 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 sequence, and preprocessing the pseudo-random base sequence vectors; Step 3: Perform a dot multiplication operation on the symbol vector and the chip vector to obtain a signal vector; Step 4: Using the signal vector as input and filtering it 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 step 1, the method for constructing a symbol-related prime number set is: First, determine the size M of the set of sign-dependent prime numbers s , the set of symbol-related prime numbers is represented by in The value can be any prime number and satisfy 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 Among them 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 set of chip-related prime numbers 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.

3. A method for generating a physical layer security waveform according to claim 2, characterized in that: In step 1, the method for constructing a codebook-related prime number set is: First, determine the size M of the chip-related prime number set c , the set of chip-related prime numbers 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.

4. A method for generating a physical layer security waveform according to claim 3, characterized in that: In step 2, the method for calculating the symbol-related codebook basis vector is: Calculate the symbol-related codebook basis vector 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 sign-dependent primes.

5. A method for generating a physical layer security waveform according to claim 4, characterized in that: In step 2, the symbol transformation matrix G is constructed. 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 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 .

6. A method for generating a physical layer security waveform according to claim 5, characterized in that: In step 2, the codebook basis vector associated with the code chip is calculated 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 based on the chip-related codebook basis vector and the repetition parameter.

7. A method for generating a physical layer security waveform according to claim 6, characterized in that: In step 2, the chip transformation matrix G is constructed. 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 are obtained after the interleaving operation.

8. A method for generating a physical layer security waveform according to claim 7, characterized in that: In step 2, a pseudo-random base complex sequence is calculated. 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 .

9. 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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