A General Multi-Channel Code-Shift Differential Chaos Shift Keying Modulation and Demodulation Method and System

Abstract

The present invention discloses a general multi-channel code shift differential chaos shift keying modulation and demodulation method and system, including: obtaining the information bits to be transmitted within the current symbol period, first performing Walsh code index modulation and polarity modulation, then using the CI code to perform secondary modulation on the modulated signal, adding the modulated signals and sending them to the demodulation system. The demodulation system first completes code index demodulation, then uses the inverse CI code for demodulation, and finally performs multiple correlation operations on each channel signal with other channel signals to obtain the optimal demodulation result. Through the present invention, the bit error performance of the system can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication technologies, and in particular, to a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system. Background Art

[0002] Traditional wireless communication systems are vulnerable to interferences such as multipath fading and signal distortion. An effective chaos communication scheme using broadband aperiodic chaotic signals as carriers can reduce power consumption and complexity and improve the anti-fading performance. Since most of the research on chaos communication is based on the transmission reference method, chaos synchronization cannot be effectively achieved at the receiving end. Among them, the differential chaos shift keying (DCSK) modulation and demodulation method does not require channel estimation, but its transceiver device needs to use a large number of radio frequency delay circuits, which limits its application in ultra-wideband systems.

[0003] In order to further improve the application performance of chaos communication, the existing use of Walsh codes for chaotic signal modulation to achieve efficient signal modulation and demodulation. Since code-shifted differential chaos shift keying (CS-DCSK) can only transmit two signals, the utilization rate of Walsh codes is low, and one of the messages is a reference signal without any useful information, resulting in low energy efficiency. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system to solve the problems of low utilization rate of Walsh codes, low energy efficiency, and poor bit error performance of the system in the existing communication scheme.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] An embodiment of the present invention provides a general multi-channel code-shift differential chaos shift keying modulation method, including:

[0009] Generating a discrete chaotic sequence with a length of β;

[0010] Select the number of signal paths M to be transmitted within a symbol period and the number of index bits n transmitted for each path according to communication requirements;

[0011] Determine Mn index bits and M-1 modulation bits within the said one symbol period;

[0012] Convert the determined M-1 modulation bits into M-1 polar modulation bits;

[0013] Generate a Walsh code of order N = 2n and an M-order CI code matrix;

[0014] Use the said Walsh code to perform the first modulation on M paths of signals;

[0015] Use the said CI code matrix to perform the second modulation on the M paths of signals after the first modulation;

[0016] Add the M paths of signals after the second modulation using an adder and transmit through an antenna.

[0017] As a preferred scheme of the general multi-path code shift differential chaos shift keying modulation method described in the present invention, wherein: the first modulation of signals by the Walsh code matrix includes:

[0018] Determine M index numbers q1,...q according to Mn index bits M ;

[0019] Select M sequences in the Walsh code matrix as modulation codes using the said M index numbers;

[0020] If and only if When the modulation code is multiplied by the discrete chaotic sequence, obtain the modulation signal y1 to complete the modulation of the first path of signal;

[0021] When the signal is other signals than the first path of signal, multiply the said modulation code by M-1 polar modulation bits to obtain modulation signals y2····y M to complete the first modulation.

[0022] As a preferred scheme of the general multi-path code shift differential chaos shift keying modulation method described in the present invention, wherein: the second modulation by the CI code matrix includes:

[0023] Perform Kronecker multiplication operations on the M-row signals obtained from the first modulation and the M rows of CI codes respectively to obtain modulation signals S1····S M to complete the second modulation.

[0024] The embodiment of the present invention also provides a general multi-channel code-shift differential chaos shift keying modulation system, including: 1 chaos signal generator, 1 Walsh code index selector, M CI code registers, 1 adder, 2M multipliers and 1 polarity converter, where:

[0025] Generate a discrete chaos sequence with a length of β by using the chaos signal generator; select the number of signal paths M to be sent within the symbol period and the number of index bits n sent for each path according to communication requirements, and determine Mn index bits and M-1 modulation bits within the symbol period; convert the M-1 modulation bits into M-1 polarity modulation bits through the polarity converter; the Walsh code index selector uses the Mn index bits to select M rows of Walsh code sequences in the Walsh code matrix; the selected first Walsh code sequence is multiplied by the chaos sequence generated by the chaos signal generator through the first multiplier to obtain the first path modulation signal y1; the selected M-1 signals are multiplied by the M-1 polarity modulation bits through M-1 multipliers to obtain the modulation signals y M ; The obtained modulation signal y1 and modulation signals y M Perform Kronecker multiplication operations through the CI code registers using M multipliers to obtain the modulation signals S1····S M , add each signal modulated by the CI code through the adder to obtain the final mixed signal, and send it through the antenna.

[0026] The embodiment of the present invention also provides a general multi-channel code-shift differential chaos shift keying demodulation method, including:

[0027] Receive the signal r from the sending end;

[0028] Perform Kronecker product operation on the received signal r and the all-ones column vector I to obtain the first matrix with a size of N×NMβ;

[0029] Based on the first matrix, perform Hadamard product operation with the extended Hadamard matrix to obtain a new matrix γ with a size of N×NMβ;

[0030] Perform a segmented averaging operation on the matrix γ to obtain the matrix with a size of N×Mβ;

[0031] Perform M Hadamard multiplication operations on the matrix and the extended M-row inverse CI code to obtain M matrices with a size of N×Mβ, where the to are respectively named as R (1) ,…,R (M) ;

[0032] Perform a segmented averaging operation on the R (1) ,…,R (M) matrix to obtain M matrices of size N×β

[0033] Take the said matrix as the input of one - end signal, and then take the said matrix as the input of M port signals for index - bit demodulation to obtain an estimated value of the first index number

[0034] Take the matrix as the input of one - end signal, and then take the said matrix as the input of M port signals for index - modulation bit demodulation to obtain an estimated value of the second index number And take the estimated value of the said index number as the input signal to obtain an estimated value of the modulation bit through index - modulation bit demodulation

[0035] Restore the modulation bits and index bits of other paths to obtain estimated values of M index numbers;

[0036] Perform a radix conversion on the obtained estimated values of M index numbers to restore an estimated value of Mn index bits, and at the same time perform a parallel - to - serial conversion on the M - 1 estimated values of modulation bits to obtain an estimated value of the modulation - bit vector

[0037] As a preferred scheme of the general multi - path code - shift differential chaos shift keying demodulation method of the present invention, wherein: the index - bit demodulation includes:

[0038] Perform a complex - conjugate operation on the input matrix y, and perform a transpose multiplication with other input matrices x1,…x M-1 to obtain M - 1 correlation matrices;

[0039] After the M - 1 correlation matrices pass through energy detection, calculate the energy of each element in the correlation matrix and find the maximum value, and obtain M - 1 estimated values of index numbers p1,…p M-1 ;

[0040] Make a decision on the M - 1 estimated values of index numbers to obtain an estimated value of the first index number

[0041] As a preferred scheme of the general multi - path code - shift differential chaos shift keying demodulation method of the present invention, wherein: the index - modulation bit demodulation includes:

[0042] Perform a complex conjugate operation on the input matrix y and perform a transpose multiplication with the input matrices x1, …, x M-1 to obtain M - 1 correlation matrices Z (M-1) ;

[0043] Obtain estimated values p1, …, p of M - 1 index numbers by performing energy detection on the M - 1 correlation matrices M-1 ;

[0044] Make a decision on the estimated values of the M - 1 index numbers to obtain an estimated value of the second index number

[0045] According to the estimated value of the first index number and the estimated value of the second index number Determine the position of the modulation bit decision variable in the first correlation matrix Z (1) and perform a mode decision to obtain an estimated value of the modulation bit

[0046] As a preferred scheme of the general multi - path code - shift differential chaos shift keying demodulation method of the present invention, wherein: the mode decision includes: judging the mode of the M - 1 index numbers according to the decision variable, and taking the mode as the optimal demodulation result;

[0047] When the decision variable is greater than 0, judge 1, and when it is less than 0, judge 0.

[0048] The embodiment of the present invention also provides a general multi - path code - shift differential chaos shift keying demodulation system, including: M + 2 multipliers, 1 Hadamard matrix register, M + 1 segmented averaging modules, M anti - CI code matrix registers, 1 index bit demodulator, M - 1 index modulation bit demodulators, 1 decimal - to - binary converter, and 1 parallel - to - serial converter;

[0049] Perform a Kronecker product operation on the received signal r from the transmitting end through M + 2 multipliers and the all - 1 column vector I, vertically replicate the signal r N times to obtain a first matrix, and perform a Hadamard product operation on the first matrix through the Hadamard matrix register and the extended Hadamard matrix to obtain a matrix γ. After passing through the first segmented averaging module, the matrix is obtained and the matrix is stored in M anti - CI code registers. Perform M Hadamard multiplication operations to obtain M matrices of size N×Mβ, and the matrices are the extended anti - CI code to which are respectively named R (1) , …, R (M) ; The R (1) , …, R (M)After passing through M segmented averaging modules, M matrices of size N×β are obtained. Input the said matrix into the y port of the index bit demodulator, input into the x1,…x M-1 ports of the index bit demodulator, perform transpose multiplication, and after energy detection, perform mode decision to obtain an estimated value of the first index number. Input the matrix into the y port of the first index modulation bit demodulator, and input the matrix into the x1,…x M-1 ports of the first index modulation bit demodulator, perform transpose multiplication, and after energy detection, perform mode decision to obtain an estimated value of the second index number. Input the estimated value of the said first index number into the port of the index modulation bit demodulator to obtain an estimated value of the first modulation bit. Input matrix R (M) into the y port of the Mth index modulation bit demodulator, and input the matrix into the x1,…x M-1 ports of the M index modulation bit demodulators, perform transpose multiplication, and after energy detection, perform mode decision to obtain an estimated value of the Mth index number. Obtain estimated values of M - 1 index numbers and estimated values of M - 1 modulation bits through M - 1 index modulation bit demodulators. After passing through a serial - to - parallel converter, convert the M - 1 modulation bit estimated values into an estimated value of a modulation bit vector. And input the estimated values of the said M index numbers into a decimal - to - binary converter to recover the estimated values of Mn index bits.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: By obtaining the information bits to be transmitted within the symbol period, performing Walsh - code index modulation and polarity modulation, using CI code to perform secondary modulation on the modulated signal, adding the modulated signals and then sending them to the demodulator; the demodulator demodulates the code index, uses the inverse CI code to demodulate each path of signal with other paths of signals to obtain the optimal demodulation result, improves the utilization rate of the Walsh code, and further improves the bit - error performance of the system. Brief Description of the Drawings

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0052] Figure 1 It is a method flow chart of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention;

[0053] Figure 2 It is a schematic structural diagram of a modulator of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention;

[0054] Figure 3 It is a schematic structural diagram of a demodulator of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention;

[0055] Figure 4 It is a specific structural diagram of an index demodulator in a demodulator of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention;

[0056] Figure 5 It is the specific structure of an index modulator-demodulator in a demodulator of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention;

[0057] Figure 6 It is an effect comparison diagram of simulation of a general multi-channel code-shift differential chaos shift keying modulation and demodulation method and system according to an embodiment of the present invention. Specific Embodiments

[0058] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific embodiments of the present invention in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0060] Second, the "one embodiment" or "embodiment" mentioned herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0061] The present invention is described in detail in conjunction with schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0062] At the same time, in the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper, lower, inner, and outer" is based on the orientation or positional relationship shown in the drawings, and is 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 a limitation of the present invention. In addition, the terms "first, second, or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0063] Unless otherwise clearly defined and limited in the present invention, the terms "mounted, connected, and coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection, an electrical connection, or a direct connection, and can also be indirectly connected through an intermediate medium, or can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0064] Embodiment 1

[0065] Referring to Figures 1 to 5 , which is an embodiment of the present invention, and this embodiment provides a general multi-channel code-shift differential chaos shift keying modulation and demodulation method.

[0066] As Figure 1 shown, a general multi-channel code-shift differential chaos shift keying modulation method designed by the present invention includes:

[0067] Step 1: Generate a discrete chaotic sequence of length β using the second-order Chebyshev mapping algorithm;

[0068] Step 2: Select the number of signal paths M to be transmitted within the symbol period and the number of index bits n transmitted for each path according to communication requirements;

[0069] Step 3: Determine Mn index bits and M - 1 modulation bits within one symbol period;

[0070] Step 4: Convert the M - 1 modulated bits determined in Step 3 into M - 1 polar - modulated bits;

[0071] Step 5: Generate a Walsh code of order N = 2 n and a CI code matrix of order M;

[0072] Step 6: Perform the first - stage modulation on the M - path signals using the Walsh code;

[0073] Step 7: Perform the second - stage modulation on the M - path signals after the first - stage modulation using the CI code matrix;

[0074] Step 8: Add the M - path signals after the second - stage modulation using an adder and transmit them through an antenna.

[0075] Step A1: Receive the signal r from the transmitter;

[0076] Step A2: Perform a Kronecker product operation on the received signal r and the all - ones column vector I to obtain a first matrix of size N×NMβ;

[0077] Step A3: Based on the first matrix, perform a Hadamard product operation with the extended Hadamard matrix to obtain a new matrix γ of size N×NMβ;

[0078] Step A4: Perform a segmented averaging operation on the matrix γ to obtain a matrix of size N×Mβ;

[0079] Step A5: Perform M Hadamard multiplication operations on the matrix and the extended M - row inverse CI code to obtain M matrices of size N×Mβ, which are the extended inverse CI codes to respectively named as R (1) ,…,R (M) ;

[0080] Step A6: Perform a segmented averaging operation on the matrices R (1) ,…,R (M) to obtain M matrices of size N×β

[0081] Step A7: Take the matrix as one - end signal input, and then take the matrix as M - port signal inputs for index - bit demodulation to obtain an estimated value of the first index number

[0082] Step A8: Take the matrix as one - end signal input, and then take the matrix Index modulation bit demodulation is performed on the M port signals as inputs to obtain an estimated value of the second index number And use the estimated value of the index number As the input signal, the estimated value of the modulation bit is obtained through index modulation bit demodulation

[0083] Step A9: Recover the modulation bits and index bits of other channels to obtain the estimated values of M index numbers;

[0084] Step A10: Perform radix conversion on the obtained estimated values of M index numbers to recover the estimated values of Mn index bits. At the same time, perform serial-to-parallel conversion on the estimated values of M - 1 modulation bits to obtain the estimated value of the modulation bit vector

[0085] Preferably, in step 6 above, the first modulation of the signal using the Walsh code matrix includes:

[0086] Determine M index numbers q1,…q according to Mn index bits M ;

[0087] Use M index numbers to select M sequences in the Walsh code matrix as modulation codes;

[0088] If and only if When the modulation code is multiplied by the discrete chaotic sequence, the modulation signal y1 is obtained, and the modulation of the first path signal is completed;

[0089] When the signal is other signals than the first path signal, The modulation code is multiplied by M - 1 polar modulation bits to obtain modulation signals y2····y M To complete the first modulation.

[0090] Preferably, in step 7 above, the second modulation using the CI code matrix includes:

[0091] Perform Kronecker multiplication operations on the M - row signals obtained from the first modulation and the M - row CI codes respectively to obtain modulation signals S1····S M To complete the second modulation.

[0092] Furthermore, in the receiving end of the above method, the Hadamard matrix Is expanded, expressed as:

[0093]

[0094] Among them, I 1×M Is a row vector of all 1s with length M, and I 1×β Is a row vector of all 1s with length β.

[0095] Further, taking the CI code of the i-th row as an example, the extension of the CI code is expressed as:

[0096]

[0097] where I 1×M is a row vector of all 1s with length M, and I 1×β is a row vector of all 1s with length β.

[0098] Preferably, the index bit demodulation includes:

[0099] Performing a complex conjugate operation on the input matrix y and multiplying it transposed with other input matrices x1,…x M-1 to obtain M - 1 correlation matrices;

[0100] After the M - 1 correlation matrices are subjected to energy detection, calculate the energy of each element in the correlation matrix and find the maximum value, and obtain the estimated values p1,…p of M - 1 index numbers through inverse index mapping M-1 ;

[0101] Making a decision on the estimated values of the M - 1 index numbers to obtain the first estimated index number

[0102] Preferably, the transposed multiplication is expressed as:

[0103]

[0104]

[0105] where represents taking the real part of the signal, conj(·) represents taking the complex conjugate of the signal, and (·) T represents the transpose operation.

[0106] Preferably, the index modulation bit demodulation includes:

[0107] Performing a complex conjugate operation on the input matrix y and multiplying it transposed with the input matrices x1,…x M-1 to obtain M - 1 correlation matrices Z (M-1) ;

[0108] Obtaining the estimated values p1,…p of M - 1 index numbers by subjecting the M - 1 correlation matrices to energy detection M-1 ;

[0109] Making a decision on the estimated values of the M - 1 index numbers to obtain the second estimated index number

[0110] According to the first estimated index number and the second estimated index number Determine the position of the modulation bit decision variable in the first correlation matrix Z(1), and perform a mode decision to obtain the estimated value of the modulation bit.

[0111] Furthermore, the mode decision includes: judging the mode of M - 1 index numbers according to the decision variable, and taking the mode as the optimal demodulation result.

[0112] When the decision variable is greater than 0, judge it as 1; when it is less than 0, judge it as 0.

[0113] On this basis, the present invention also provides a general multi - path code - shift differential chaos shift keying modulation and demodulation system, which can modulate and demodulate signals by using the above - mentioned method.

[0114] A general multi - path code - shift differential chaos shift keying modulation system provided by an embodiment of the present invention, as shown in Figure 2, specifically includes: 1 chaos signal generator, 1 Walsh code index selector, M CI code registers, 1 adder, 2M multipliers, and 1 polarity converter, where:

[0115] Generate a discrete chaos sequence with a length of β by using the chaos signal generator; select the number of signal paths M to be transmitted within the symbol period and the number of index bits n transmitted for each path according to communication requirements, and determine Mn index bits and M - 1 modulation bits within the symbol period; convert the M - 1 modulation bits into M - 1 polarity modulation bits through the polarity converter; the Walsh code index selector selects M - row Walsh code sequences in the Walsh code matrix by using Mn index bits; the selected first Walsh code sequence is multiplied by the chaos sequence generated by the chaos signal generator through the first multiplier to obtain the first - path modulation signal y1; the selected M - 1 signals are multiplied by the M - 1 polarity modulation bits through M - 1 multipliers to obtain the modulation signal y M ; Combine the obtained modulation signal y1 and the modulation signal y M Perform Kronecker multiplication operations on the CI code registers by using M multipliers to obtain the modulation signals S1 ··· S M , add each signal modulated by the CI code through the adder to obtain the final mixed signal, and send it through the antenna.

[0116] An embodiment of the present invention also provides a general multi - path code - shift differential chaos shift keying demodulation system, as Figures 3 to 5 shown, specifically includes: M + 2 multipliers, 1 Hadamard matrix register, M + 1 segment - average modules, M inverse CI code matrix registers, 1 index bit demodulator, M - 1 index modulation bit demodulators, 1 decimal - to - binary converter, and 1 serial - to - parallel converter;

[0117] The received transmitter signal r is subjected to a Kronecker product operation with the all-ones column vector I through M + 2 multipliers, and the signal r is vertically replicated N times to obtain a first matrix. According to the first matrix, a Hadamard product operation is performed with the extended Hadamard matrix through the Hadamard matrix register to obtain a matrix γ, and after passing through the first segmented averaging module, the matrix is obtained and stored in M anti-CI code registers to perform M Hadamard multiplication operations to obtain M matrices of size N×Mβ, where the matrix is the extended anti-CI code to which are respectively named R (1) ,…,R (M) ; R (1) ,…,R (M) After passing through M segmented averaging modules, M matrices of size N×β are obtained The matrix is input to the y port of the index bit demodulator, and the x1,…x M-1 ports of the index bit demodulator are input. After transpose multiplication and energy detection, a mode decision is performed to obtain an estimated value of the first index number The matrix is input to the y port of the first index modulation bit demodulator, and the matrix is input to the x1,…x M-1 ports of the first index modulation bit demodulator. After transpose multiplication and energy detection, a mode decision is performed to obtain an estimated value of the second index number The estimated value of the first index number is input to the port of the index modulation bit demodulator to obtain an estimated value of the first modulation bit The matrix R (M) is input to the y port of the Mth index modulation bit demodulator, and the matrix is input to the x1,…x M-1 ports of the M index modulation bit demodulators. After transpose multiplication and energy detection, a mode decision is performed to obtain an estimated value of the Mth index number Estimated values of M - 1 index numbers are obtained through M - 1 index modulation bit demodulators as well as estimated values of M - 1 modulation bits After passing through a parallel-to-serial converter, the estimated values of the M - 1 modulation bits are converted into an estimated value of the modulation bit vector And the estimated values of the M index numbers are fed into a decimal-to-binary converter to recover the estimated values of the Mn index bits.

[0118] In an alternative embodiment, to verify that the general multi - channel code - shift differential chaos shift keying modulation and demodulation method provided by the present invention can improve the bit error performance of the system, the present invention lists a verification example for verification and description. The method of this verification example includes the following steps:

[0119] Step 1: Generate a discrete chaotic sequence C with a length of β = 100 using a second - order Chebyshev map.

[0120] Step 2: Select the number of signal paths M = 4 to be transmitted within a symbol period and the number of index bits n = 3 transmitted for each path according to the requirements of the communication system.

[0121] Step 3: Determine 12 index bits b1 = {b 1.1 ,b 1.2 ,b 1.3}, b2 = {b 2.1 ,b 2.2 ,b 2.3}, b3 = {b 3.1 ,b 3.2 ,b 3.3} and 3 modulation bits a = {a1, a2, a3} within a symbol period.

[0122] Step 4: Use a polarity converter to convert the 3 modulation bits generated in Step 3 into 3 polar modulation bits a' = {a'1, a'2, a'3}.

[0123] Step 5: Generate an N = 2 3 = 8 - order Walsh code matrix and a 4 - order CI code matrix.

[0124] Step 6: Perform the first modulation on the signal using the Walsh code matrix generated in Step 4. First, determine 4 index numbers q1,…,q4 according to the 12 index bits, and then select 4 sequences from the Walsh codes as modulation codes using these 4 index numbers Then modulate them with the chaotic sequence respectively. For signals other than the first path, modulate them again using the polar modulation bits a' = {a'1, a'2, a'3}.

[0125] Step 7: Perform the second modulation on the signal modulated for the first time using the CI code matrix generated in Step 4 to ensure correct decoding and separation at the receiving end. Specifically, modulate the 4 signals modulated by the Walsh code with the CI code respectively.

[0126] Step 8: Add the 4 signals modulated for the second time using an adder and transmit them through an antenna.

[0127] At the receiving end, receive and demodulate the signal, specifically including:

[0128] Step 9: Receive the signal r from the transmitter end.

[0129] Step 10: Use a multiplier to perform a Kronecker product operation on the received signal r and the all-ones column vector I. This all-ones column vector I has a dimension of 8, and the purpose of the Kronecker product is to replicate the received signal r vertically 8 times to obtain a matrix of size 8×3200.

[0130] Step 11: Based on the matrix obtained in Step 10, perform a Hadamard product operation with the extended Hadamard matrix to obtain a new matrix γ with a size of 8×3200.

[0131] Step 12: Perform a segmented averaging operation on the matrix obtained in Step 11 to obtain a matrix of size 8×400

[0132] Step 13: Based on the matrix obtained in Step 12 , use 4 multipliers to perform 4 Hadamard multiplication operations on this matrix respectively, where the multiplier for each Hadamard multiplication operation is the extended inverse CI code to thus obtaining 4 matrices of size 8×400, named R (1) ,…,R (4) .

[0133] Step 14: For the 4 matrices obtained in Step 13, a segmented averaging operation needs to be performed on each matrix, thus obtaining 4 matrices of size 8×100

[0134] Step 15: Input the matrix obtained in Step 14 into the y port of the index bit demodulator, input into the x1,…x3 ports of the index bit demodulator to demodulate the estimated value of the first index number

[0135] Step 15.1: In the index bit demodulator, perform a complex conjugate operation on the input matrix y, and then perform a transpose multiplication with the other input matrices x1,…x3 to obtain 3 correlation matrices.

[0136] Step 15.2: After passing the 3 correlation matrices generated in Step 15.1 through an energy detector, calculate the energy of each element in the correlation matrix and find the maximum value, and obtain 3 estimated values p1,…p3 of the index number through inverse index mapping.

[0137] Step 15.3: Send all the estimated values of the three index numbers obtained in Step 15.2 into the mode discriminator, and use the estimated value of the index number that appears the most times as the final estimated value of the index number.

[0138] Step 16: Send the matrix obtained in Step 14 into the y port of the index modulation bit demodulator, and send the matrix into the x1,…x3 ports of the index modulation bit demodulator to demodulate the estimated value of the second index number. Also send the estimated value of the index number obtained in Step 15 into the port of the index modulation bit demodulator to demodulate the estimated value of the first modulated bit.

[0139] Step 16.1: In the index modulation bit demodulator, perform a complex conjugate operation on the input matrix y, and then perform a transpose multiplication with the other input matrices x1,…x3 to obtain three correlation matrices.

[0140] Step 16.2: After passing the three correlation matrices generated in Step A8.1 through the energy detector, obtain three estimated values p1,…p3 of the index number.

[0141] Step 16.3: Send all the estimated values of the three index numbers obtained in Step 16.2 into the mode discriminator, and use the estimated value of the index number that appears the most times as the final estimated value of the index number.

[0142] Step 16.4: Send the estimated value of the index number obtained in Step 16.3 the estimated value of the index number obtained in Step 15 and the first correlation matrix Z1 in Step 16.1 into the modulation bit discriminator. Based on and determine the position of the decision variable to which the modulation bit belongs in Z1, and perform a threshold decision to obtain the estimated value of the modulation bit.

[0143] Step 17: Restore the modulated bits and index bits of the other channels. The steps are the same as those in Step 16.

[0144] Step 18: Send the estimated values of the four index numbers obtained in Steps 15, 16, and 17 into the decimal-to-binary converter to restore the estimated values of 12 index bits. At the same time, send the estimated values of the three modulated bits obtained in Steps 16 and 17 into the parallel-to-serial converter to obtain the estimated value of the modulated bit vector.

[0145] Embodiment 2

[0146] Reference Figure 6 , which is an embodiment of the present invention. A transmission experiment is carried out on the general multi-channel code shift differential chaos shift keying modulation and demodulation method provided by the present invention through computer simulation.

[0147] In this embodiment, an eight-order Walsh code is adopted, the length of the chaotic sequence is 180, and the signal transmission is 4-channel signals. Reference Figure 6 is the simulation comparison effect diagram of the method of the present invention and the traditional method. As Figure 6 shown, the bit error rates of the method of the present invention and the traditional method are obtained by simulation under the same conditions. It can be seen from the figure that compared with the traditional method, the method of the present invention makes full use of the Walsh code for modulation and demodulation, and greatly reduces the bit error rate, showing better bit error performance.

[0148] In summary, the present invention obtains the information bits to be transmitted within the symbol period, performs Walsh code index modulation and polarity modulation, uses the CI code to perform secondary modulation on the modulated signal, adds the modulated signals and then sends them to the demodulator; the demodulator demodulates the code index, uses the inverse CI code to demodulate each channel signal with other channel signals to obtain the optimal demodulation result, improves the utilization rate of the Walsh code, and further improves the bit error performance of the system.

[0149] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A general multi-channel code-shift differential chaos shift keying modulation method, characterized in that Including: Generating a discrete chaotic sequence of length β; Selecting the number of signal paths M to be transmitted within a symbol period and the number of index bits n transmitted for each path according to communication requirements; Determining M×n index bits and M - 1 modulation bits within a symbol period; Converting the determined M - 1 modulation bits into M - 1 polar modulation bits; Generate Walsh codes of order N = 2 n and CI code matrices of order M; Perform the first modulation on the M signals using the Walsh code, and determine M index numbers q1, …, q according to M×n index bits M ; Selecting M sequences from the Walsh code matrix using the M index numbers as modulation codes; if and only if When the modulation code is multiplied by the discrete chaotic sequence, the modulation signal y1 is obtained, and the modulation of the first path of signal is completed; When the signal is other than the first signal, multiply the modulation code by M - 1 polar modulation bits to obtain a modulation signal y2····y M , and complete the first modulation; The M signals after the first modulation are subjected to a second modulation using the CI code matrix. The M-row signals obtained from the first modulation and the M rows of CI codes are respectively subjected to Kronecker multiplication operations to obtain modulation signals S1 ··· S M , thus completing the second modulation; Adding the M paths of signals after the second modulation using an adder and transmitting through an antenna.

2. A general multi-channel code-shift differential chaos shift keying modulation system, characterized in that, Including: 1 chaotic signal generator, 1 Walsh code index selector, M CI code registers, 1 adder, 2M multipliers, and 1 polarity converter, where: Generate a discrete chaotic sequence of length β using the chaotic signal generator; select the number of signal paths M to be transmitted within the symbol period and the number of index bits n transmitted for each path according to communication requirements, and determine M×n index bits and M−1 modulation bits within the symbol period; convert the M−1 modulation bits into M−1 polar modulation bits through a polarity converter; the Walsh code index selector selects M rows of Walsh code sequences in the Walsh code matrix using the M×n index bits; the first selected Walsh code sequence is multiplied by the chaotic sequence generated by the chaotic signal generator through a first multiplier to obtain the first path of modulated signal y1; the selected M−1 signals are multiplied by the M−1 polar modulation bits through M−1 multipliers to obtain the modulated signal y M ; the obtained modulated signal y1 and the modulated signal y M are subjected to Kronecker multiplication operations through M multipliers using a CI code register to obtain the modulated signals S1····S M , add each signal modulated by the CI code through an adder to obtain the final mixed signal, and transmit it through an antenna.

3. A general multi-channel code-shift differential chaos shift keying demodulation method, characterized in that Including: Receiving the signal r from the transmitting end; Performing a Kronecker product operation on the received signal r and the all - 1 column vector I to obtain a first matrix of size N×NMβ, where N is the Walsh code order, M is the number of signal paths, and β is the discrete chaotic sequence; Based on the first matrix, perform the Hadamard product operation with the extended Hadamard matrix to obtain a new matrix γ with a size of N × NMβ; Perform a segmented averaging operation on the matrix γ to obtain a matrix with a size of N×Mβ; Multiply the said matrix by the expanded M-row anti-CI code M times using Hadamard multiplication to obtain M matrices of size N×Mβ, where the multiplier for each Hadamard multiplication is the expanded anti-CI code to which are respectively named as R (1) ,…,R (M) ; Perform a segmented averaging operation on the R (1) ,…,R (M) matrix to obtain M matrices of size N×β Take the said matrix as the input of one - end signal, and then take the said matrix as the input of M - port signals for index bit demodulation to obtain the estimated value of the first index number Take the matrix as the input of one - end signal. Then take the matrix as the input of M - port signals for index - modulation bit demodulation to obtain the estimated value of the second index number And take the estimated value of the index number as the input signal to obtain the estimated value of the modulation bit through index - modulation bit demodulation Recovering the modulation bits and index bits of other paths to obtain estimated values of M index numbers; Perform radix conversion on the obtained estimated values of the M index numbers to recover the estimated values of the Mn index bits, and at the same time perform parallel-to-serial conversion on the estimated values of the M - 1 modulation bits to obtain the estimated value of the modulation bit vector 4. The general multi-channel code shift differential chaos shift keying demodulation method according to claim 3, characterized in that Index bit demodulation includes: Perform a complex conjugate operation on the input matrix y and transpose and multiply it with other input matrices x1, … x M-1 to obtain M - 1 correlation matrices; After the M-1 correlation matrices are subjected to energy detection, calculate the energy of each element in the correlation matrix and find the maximum value, and obtain the estimated values p1, …, p of the M-1 index numbers through inverse index mapping M-1 ; Judge the estimated values of the M-1 index numbers to obtain the first estimated index number 5. The general multi-channel code-shift differential chaos shift keying demodulation method according to claim 4, characterized in that: The transpose multiplication, expressed as: Among them, represents taking the real part of the signal, conj(·) represents taking the complex conjugate of the signal, and (·) T represents the transpose operation.

6. The general multi-channel code shift differential chaos shift keying demodulation method according to claim 5, characterized in that, Index - modulated bit demodulation, including: Perform a complex conjugate operation on the input matrix y and multiply it transposed with the input matrices x1, …, x M-1 to obtain M - 1 correlation matrices Z (M-1) ; The M-1 correlation matrices are subjected to energy detection to obtain estimated values p1, …, p of M-1 index numbers M-1 ; Judge the estimated values of the M-1 index numbers to obtain an estimated value of a second index number Estimate according to the first index number estimate value and the second index number estimate value Determine the position of the modulation bit decision variable in the first correlation matrix Z (1) and perform a mode decision to obtain the estimated value of the modulation bit 7. The general multi-channel code shift differential chaos shift keying demodulation method according to claim 6, characterized in that The mode decision includes: Judging the mode of M - 1 index numbers according to the decision variable and taking the mode as the optimal demodulation result; When the decision variable is greater than 0, judge 1; when it is less than 0, judge 0.

8. A general multi-channel code shift differential chaos shift keying demodulation system, characterized in that, Including: M + 2 multipliers, 1 Hadamard matrix register, M + 1 segmented averaging modules, M inverse CI code matrix registers, 1 index bit demodulator, M - 1 index - modulated bit demodulators, 1 decimal - to - binary converter, 1 parallel - to - serial converter; The received transmitter signal r is subjected to a Kronecker product operation with the all-ones column vector I through M+2 multipliers, and the signal r is vertically replicated N times to obtain a first matrix. According to the first matrix, a Hadamard product operation is performed with the Hadamard matrix register and the extended Hadamard matrix to obtain a matrix γ, and the matrix γ is passed through a first segmented averaging module to obtain a matrix and the matrix is stored in M anti-CI code registers to perform M Hadamard multiplication operations to obtain M matrices of size N×Mβ, where N is the Walsh code order, M is the number of signal paths, and β is the discrete chaotic sequence. The matrix is the extended anti-CI code to which are respectively named R (1) ,…,R (M) ; the R (1) ,…,R (M) after passing through M segmented averaging modules to obtain M matrices of size N×β The matrix is input to the y port of the index bit demodulator, the x1,…x M-1 ports of the index bit demodulator are input, and after transpose multiplication and energy detection, a mode decision is made to obtain an estimated value of the first index number The matrix is input to the y port of the first index modulation bit demodulator, and the matrix is input to the x1,…x M-1 ports of the first index modulation bit demodulator. After transpose multiplication and energy detection, a mode decision is made to obtain an estimated value of the second index number The estimated value of the first index number is input to the port of the index modulation bit demodulator to obtain an estimated value of the first modulation bit The matrix R (M) is input to the y port of the Mth index modulation bit demodulator, and the matrix is input to the x1,…x M-1 ports of the M index modulation bit demodulators. After transpose multiplication and energy detection, a mode decision is made to obtain an estimated value of the Mth index number Estimated values of M-1 index numbers are obtained through M-1 index modulation bit demodulators and estimated values of M-1 modulation bits After passing through a parallel-to-serial converter, the estimated values of the M-1 modulation bits are converted into an estimated value of the modulation bit vector and the estimated values of the M index numbers are fed into a decimal-to-binary converter to recover the estimated values of Mn index bits.

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