A reconfigurable anti-interception light encoding code word design method

Abstract

The application is suitable for the field of coding technology improvement, and provides a reconfigurable anti-interception optical coding code word design method, which comprises the following steps: S1, constructing a wavelength frequency hopping sequence by setting p as an integer; S2, randomly taking p values {T1, T2, …, T i , …, T p} and obtaining combinations thereof; S3, taking any one of p p combinations to construct a corresponding time domain spread spectrum code; S4, constructing a code word reconfiguration space of a legal user according to the time domain frequency hopping code and the wavelength frequency hopping sequence; and S5, constructing a corresponding interference user address code by using a legal user address code. The code word reconfiguration space of a single legal user is greatly increased, so that the information of the legal user can be effectively prevented from being cracked by a listener through code word searching, and the physical layer security of the optical network is increased. Therefore, the reconfigurable anti-interception optical coding method can significantly improve the physical layer security of the OCDMA system and is applied to optical fiber access networks, wireless optical communication, optical transmission networks and the like with high physical layer security requirements.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of coding technology improvement, and particularly relates to a reconfigurable anti-interception optical coding code word design method. BACKGROUND

[0002] Optical code division multiple access (OCDMA) system has multiple protection functions, and can realize safe transmission of optical information. Main advantages include anti-interception, anti-attack, identity authentication, and concealment. In order to avoid eavesdroppers from cracking by scanning the address code of legal users one by one with code word search method, it is necessary to design a reconfigurable large-capacity optical address code.

[0003] At present, many scholars at home and abroad have constructed various OCDMA address codes. Sharr.A.A. et al. constructed prime number (PC) code, the code word capacity of which is p-1, the code length is p 2 , the code weight is p, and the cross-correlation limit is 2. Maric.S. et al. proposed a new extended prime code (EPC), which improves the cross-correlation characteristics of the code word by inserting p-1 "0"s after each basic prime code sequence, the code word capacity of which is p, the code length is p(2p-1), the code weight is p, and the cross-correlation limit is 1. Sharr.A.A. et al. constructed optical orthogonal code, the autocorrelation limit of which is 1, the cross-correlation between the code words of the optical orthogonal code is 1, which is called equal weight optical orthogonal code, and the upper bound of the code word capacity is determined by Johnson bound. The construction methods of the optical orthogonal code include direct construction method, algebraic construction method and recursive construction method. Based on the prime code, Tancevski.L. et al. constructed PC / PC and EQC / PC, the code word capacity of the PC / PC code is p(p-1) 2 , the code length is p 2 , the code weight is p, the autocorrelation limit is 0, and the cross-correlation limit is 1. The code word capacity of the EQC / PC is p(p-1) 2 , the code length is p(2p-1), the code weight is p, the autocorrelation limit is 0, and the cross-correlation limit is 2. Wan Shengpeng et al. constructed PC / OOC code based on the prime code and the optical orthogonal code, the code word capacity of which is mpL, the code length is pL, the code weight is m, the autocorrelation limit is 0, and the cross-correlation limit is 1. Li Chuanqi et al. constructed two-dimensional 2D-OOC code and QPC code. The code word capacity of the 2D-OOC code is n(n+1)Φ, the code length is n 2 , the code weight is n, Φ is the code word capacity of one-dimensional OOC with the same code length and code weight, the autocorrelation limit is 0, and the cross-correlation limit is 1. Zhou Xiuli et al. constructed MPC / OOC code based on the optical orthogonal frequency hopping code and the improved prime code, the code word capacity of which is p 2 LΦ, the code length is p 2, the code weight is p, the available wavelength number is L, the autocorrelation limit is 0, and the cross-correlation limit is 1. Yin Hongxi et al. constructed a two-dimensional OCFHC / OOC code, which uses OCFHC and OOC as wavelength hopping and time expansion modes respectively, provides more available wavelengths, and theoretically reaches the upper bound of the code word capacity with the autocorrelation limit of 0 and the cross-correlation limit of 1. Chen Zhiwen et al. constructed a two-dimensional bipolar single coincidence sequence BOCS based on the single coincidence sequence OCS, and when the code length is N, the code word capacity of BOCS is N times that of OCS. Tan Pengfei et al. constructed an ESPC / QCHC code, the code word capacity of which is pq(q-1), the code length is p(2p-1), the code weight is p, the autocorrelation limit is 0, and the cross-correlation limit is 1. Guan Chenglong et al. use a modified quadratic prime code MSPC as a time expansion sequence and OCS as a frequency hopping sequence, and compared with the PC / OCS code, the code word capacity is increased while the correlation between code words is smaller, which can reduce the error rate of the system. Tan Yeting et al. constructed a large-capacity two-dimensional frequency hopping / time expansion address code, in which only one legal user is the main user, and the others are interference users, and the interference users only need to be orthogonal to the main user, and the interference users do not need to be orthogonal, which significantly improves the code word capacity of the legal user.

[0004] When evaluating the security of the system from the perspective of code word capacity, the time used by the eavesdropper for brute force search will become longer as the code word capacity increases, indicating that the higher the security of the system. However, due to the strict orthogonality between the address codes at present, the code word capacity is relatively limited and cannot resist the brute force search attack of the eavesdropper. When the eavesdropper uses a brute force search attack, it only needs to search all code words one by one to crack the information of the legal user. For example, the PC / PC code with a code weight of 5 and a code length of 25 has a code word capacity of only 20. Therefore, it is necessary to improve the code word capacity of the address code. On the other hand, in order to further prevent the brute force search attack of the eavesdropper and code word interception, an effective method is to use reconfigurable optical coding. In theory, as long as the code word switching speed is fast enough and the code word reconfiguration space is large enough, the eavesdropper cannot effectively crack the code word of the legal user. Therefore, in order to improve the physical layer security of the OCDMA system, it is necessary to design a reconfigurable large-capacity address code to effectively prevent the brute force search attack of the eavesdropper. SUMMARY

[0005] The purpose of the present application is to provide a reconfigurable anti-interception optical coding code word design method, which aims to solve the above technical problems.

[0006] The present application is realized in this way, a reconfigurable anti-interception optical coding code word design method, the reconfigurable anti-interception optical coding code word design method comprises the following steps:

[0007] S1, a wavelength hopping sequence is constructed by setting p as an integer;

[0008] S2. Randomly select p values ​​{T1, T2, ..., T...} i ,…,T p}, obtain its combination;

[0009] S3, take p p Any combination of these combinations constitutes the corresponding time-domain spreading code;

[0010] S4. Construct the codeword reconstruction space for legitimate users based on the time-domain spreading code and wavelength frequency hopping sequence;

[0011] S5. Construct corresponding interference user address codes using legitimate user address codes.

[0012] A further technical solution of the present invention is: in step S1, p! permutations are formed for p integers {0, 1, ..., p-1}, such that each permutation constitutes a wavelength frequency hopping sequence.

[0013] A further technical solution of the present invention is: in step S2, p values ​​{T1, T2, ..., T} are randomly selected. i ,…,T p}, obtain its total p p There are several combinations, among which T i The range of values ​​for is {0, 1, ..., p-1}.

[0014] A further technical solution of the present invention is: each T in step S3 i The value is expanded into a sub-block of length p, which includes one 1 and (p-1) 0s, and the position of the 1 depends on T. i value.

[0015] A further technical solution of the present invention is: in step S3, for any integer p, there are a total of p p A time-domain spreading code.

[0016] A further technical solution of the present invention is that step S4 further includes the following step:

[0017] S41. Select any time-domain spreading code and a wavelength frequency hopping sequence, and combine the two to form a valid user address code.

[0018] A further technical solution of the present invention is: in step S41, any integer p has a total of p p p! different codewords constitute the codeword reconstruction space of legitimate users.

[0019] A further technical solution of the present invention is: in step S5, different cyclic right shifts are performed on the pulses in each sub-block of each legitimate user address code to construct the corresponding interference user address code.

[0020] The further technical scheme of the present application is that in the reconfigurable anti-interception optical coding code word design method, for any legal user address code, p! corresponding interference user address codes can be constructed.

[0021] The present application has the following advantages: on the one hand, the method only needs to ensure that the code word of the interference user is orthogonal to each legal user code word, and the code words of the interference users do not need to be orthogonal, thereby greatly improving the code word capacity of the interference users. On the other hand, the code word reconstruction space of a single legal user will be greatly increased, thereby effectively preventing a eavesdropper from cracking the legal user information through code word search, and increasing the physical layer security of the optical network. The physical layer security of the OCDMA system can be significantly improved, and the present application can be applied to optical fiber access networks, wireless optical communication, optical transmission networks and the like with high physical layer security requirements. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flow chart of the reconfigurable anti-interception optical coding code word design method provided by the embodiment of the present application.

[0023] Figure 2 is a schematic diagram of the cross-correlation values of a legal user 1 and its interference users.

[0024] Figure 3 is a schematic diagram of the cross-correlation values of a legal user 2 and its interference users.

[0025] Figure 4 is a schematic diagram of the cross-correlation values of a legal user 3 and its interference users.

[0026] Figure 5 is a schematic diagram of the cross-correlation values of a legal user 4 and its interference users. DETAILED DESCRIPTION

[0027] The present application provides a reconfigurable anti-interception optical coding method and code word design, and the code word of the interference user only needs to be orthogonal to the code word of the legal user, and the code words of the interference users do not need to be orthogonal, which greatly increases the number of code words of the interference users in the system. At the same time, since the code word reconstruction space of a single legal user is greatly increased, the anti-interception performance of the system is significantly improved.

[0028] As shown in Figure 1 The flow chart of the reconfigurable anti-interception optical coding code word design method provided by the present application is shown in the following:

[0029] In step S1, a wavelength frequency hopping sequence is constructed by setting p as an integer; p is any integer, and first, p! permutations are constructed for p integers {0, 1, …, p-1}, and taking p=3 as an example,

[0030] S1 = {0, 1, 2}, S2 = {0, 2, 1}, S3 = {1, 0, 2}, S4 = {1, 2, 0}, S5 = {2, 0, 1}, S6 = {2, 1, 0}, each permutation constitutes a wavelength hopping sequence.

[0031] Step S2, take p values {T1, T2,..., Tp} randomly, get its combination; take p values {T1, T2,..., Tp} randomly, where the value range of Tp is {0, 1,..., p-1}. Take p = 3 as an example, so the combination has 3 i = 27, including: {0, 0, 0}, {0, 0, 1}, {0, 0, 2}, {0, 1, 0}, {0, 1, 1}, {0, 1, 2},..., {2, 2, 2}. Obviously, for any integer p, there are p p combinations. i p i 3 p

[0032] Step S3, take any one of the p p combinations to constitute the corresponding time domain spread code; take any one combination, each T i value is expanded to a sub-block with a length of p, which includes 1 1 and (p-1) 0, and the position of 1 depends on the T i value. For example, {0, 0, 0} corresponds to the time domain spread code {100, 100, 100}; {0, 0, 1} corresponds to the time domain spread code {100, 100, 010}; {0, 0, 2} corresponds to the time domain spread code {100, 100, 001};..., {2, 2, 2} corresponds to the time domain spread code {001, 001, 001}. Obviously, for any integer p, there are p p time domain spread codes.

[0033] Step S4, reconstruct the code word space of the legitimate user according to the time domain spread code and the wavelength hopping sequence; select any one time domain spread code and any one wavelength hopping sequence, and the two constitute the address code of a legitimate user. For example, select the time domain spread code {100, 010, 001}, and at the same time select the wavelength hopping sequence S1 = {0, 1, 2}, then the two-dimensional code is {λ000, 0λ10, 00λ2}. Obviously, for any prime number p, there are p p p! different code words, which constitutes the code word reconstruction space of the legitimate user.

[0034] ​​​​​Step S5, constructing corresponding interference user address code by using legal user address code; for each legal user address code, performing different cyclic right shift on the pulse in each sub-block, thereby constructing corresponding interference user address code. For example, legal user code word {λ000, 0λ10, 00λ2}, performing different cyclic right shift on the pulse in each sub-block, totally 3! = 6, that is, 6 interference user address codes can be constructed. For example, cyclic delay (0, 1, 2) corresponding code word is {λ000, 00λ1, 0λ20}; cyclic delay (0, 2, 1), corresponding code word is {λ000, λ100, λ200}; cyclic delay (1, 0, 2), corresponding code word is {0λ00, 0λ10, 0λ20}; cyclic delay (1, 2, 0), corresponding code word is {0λ00, λ100, 00λ2}; cyclic delay (2, 0, 1), corresponding code word is {00λ0, 0λ10, λ200}; cyclic delay (2, 1, 0), corresponding code word is {00λ0, 00λ1, 00λ2}. Therefore, given any prime number p, for any legal user address code, corresponding interference user address code can be constructed totally p!.

[0035] The total code word capacity of the conventional prime number frequency hopping code is p(p-1) given prime number p, while the reconfigurable anti-interception code constructed in the present application has p p p! code word reconfiguration space for legal users. Meanwhile, for each legal user address code, corresponding interference user address code is totally p!. For example, p = 31, code word reconfiguration space for legal users is 1.4E+80, while interference code word for each legal user code word is 8.2E+33. In this way, the reconfigurable anti-interception code constructed in the present application not only greatly increases the code word reconfiguration space for legal users, but also greatly increases the code word capacity for interference users, thereby effectively preventing brute force search attack and improving the physical layer security of the OCDMA system.

[0036] Table 1 part of code words for legal users and interference users when p = 4

[0037]

[0038]

[0039] Based on the code words in Table 1, the cross-correlation values of legal user code word and corresponding interference code word are calculated:

[0040] The cross-correlation values of legal user 1 and its interference users are shown in Figure 2 .

[0041] The cross-correlation values of legal user 2 and its interference users are shown in Figure 3 .

[0042] The cross-correlation values of the legitimate user 3 and its interfering users are shown as Figure 4

[0043] The cross-correlation values of the legitimate user 4 and its interfering users are shown as Figure 5

[0044] The reconfigurable anti-interception optical coding code word design method can increase the code word reconfiguration space of the legitimate user and the code word capacity of the interfering user, thereby improving the anti-interception performance of the OCDMA system. In the traditional optical address code, the code words of the users must be orthogonal to each other, so the code word capacity is limited, and the code word information of the legitimate user can be cracked by the eavesdropper through code word search. The reconfigurable anti-interception optical coding method and code word design of the present application only need to satisfy that the code words of the interfering users are orthogonal to the code words of the legitimate users, and the code words of the interfering users do not need to be orthogonal, thereby expanding the code word reconfiguration space of the legitimate user and the code word capacity of the interfering user, which can effectively prevent the eavesdropper from cracking the code word information of the legitimate user through code word search, and increase the physical layer security of the optical network. Therefore, the reconfigurable anti-interception optical coding method and code word design of the present application can effectively improve the physical layer security of the OCDMA system. On the one hand, only the code words of the interfering users are orthogonal to the code words of each legitimate user, and the code words of the interfering users do not need to be orthogonal, thereby greatly improving the code word capacity of the interfering user. On the other hand, the code word reconfiguration space of a single legitimate user will be greatly increased, thereby effectively preventing the eavesdropper from cracking the legitimate user information through code word search, and increasing the physical layer security of the optical network. Therefore, the reconfigurable anti-interception optical coding method of the present application can significantly improve the physical layer security of the OCDMA system, and is applied to the optical fiber access network, wireless optical communication, optical transmission network and the like with high physical layer security requirements.

[0045] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.​​

Claims

1. A method for designing reconfigurable, intercept-resistant optical coded codewords, characterized in that, The reconfigurable anti-interception optical codeword design method includes the following steps: S1. Use the setting that p is an integer to construct a wavelength frequency hopping sequence; S2. Randomly select p values ​​{T1, T2, ..., T} i ,…, T p }, obtain its combination; S3, take p p Any combination of these combinations constitutes the corresponding time-domain spreading code; S4. Construct the codeword reconstruction space for legitimate users based on the time-domain spreading code and wavelength frequency hopping sequence; S5. Construct corresponding interference user address codes using legitimate user address codes; In step S1, p integers {0, 1, ..., p-1} are arranged into p! permutations, such that each permutation constitutes a wavelength frequency hopping sequence; In step S2, p values ​​{T1, T2, ..., T} are randomly selected. i ,…, T p }, obtain its total p p There are several combinations, among which T i The range of values ​​for is {0, 1, ..., p-1}.

2. The reconfigurable anti-interception optical codeword design method according to claim 1, characterized in that, Each T in step S3 i The value is expanded into a sub-block of length p, which includes one 1 and (p-1) 0s, and the position of the 1 depends on T. i value.

3. The reconfigurable anti-interception optical codeword design method according to claim 2, characterized in that, In step S3, for any integer p, there are a total of p p A time-domain spreading code.

4. The reconfigurable anti-interception optical codeword design method according to claim 3, characterized in that, Step S4 also includes the following steps: S41. Select any time-domain spreading code and a wavelength frequency hopping sequence, and combine the two to form a valid user address code.

5. The reconfigurable anti-interception optical codeword design method according to claim 4, characterized in that, In step S41, any integer p has a total of p p p! different codewords constitute the codeword reconstruction space of legitimate users.

6. The reconfigurable anti-interception optical codeword design method according to claim 5, characterized in that, In step S5, different cyclic right shifts are performed on the pulses in each sub-block of each legitimate user address code to construct the corresponding interference user address code.

7. The reconfigurable anti-interception optical codeword design method according to claim 6, characterized in that, In the reconfigurable anti-interception optical coding codeword design method, by setting any integer p, a total of p! corresponding interference user address codes can be constructed for any legal user address code.

Images