A pilot sequence design method and device for a non-orthogonal multi-carrier transmission system

Abstract

The present invention discloses a pilot sequence design method and device for a non-orthogonal multi-carrier transmission system, the method comprising: initializing the non-orthogonal multi-carrier transmission system; generating a transmission signal for the initialized non-orthogonal multi-carrier transmission system; generating a reception signal taking into account the influence of noise and carrier frequency deviation on the transmission signal when passing through a wireless channel; calculating a joint probability density distribution function for the reception signal, and taking the natural logarithm of the joint probability density distribution function to generate a log-likelihood function; taking partial derivatives of variables in the log-likelihood function to calculate an information matrix; calculating a theoretical performance bound for frequency deviation estimation according to the information matrix, and constructing an objective function for pilot optimization based on the theoretical performance bound; solving the objective function to obtain a pilot sequence for the non-orthogonal multi-carrier transmission system; the pilot sequence proposed by the present invention can achieve better frequency deviation estimation performance than traditional M sequence, Gold sequence, and ZC sequence.

Description

Technical Field

[0001] The present invention relates to a pilot sequence design method and device for a non-orthogonal multi-carrier transmission system, belonging to the technical field. Background Art

[0002] Spectral efficiency is a key goal in wireless communications. Non-orthogonal modulation techniques, which achieve higher spectral efficiency than traditional orthogonal modulation, have attracted considerable research attention. Compared to traditional orthogonal modulation, non-orthogonal modulation techniques primarily improve spectral efficiency by further reducing the symbol transmission interval or subcarrier spacing. A representative example of non-orthogonal modulation techniques is non-orthogonal multi-carrier transmission.

[0003] While non-orthogonal multi-carrier transmission technology can improve spectral efficiency to a certain extent, the artificially introduced inter-subcarrier interference and inter-symbol interference (ISI) make frequency offset and timing offset estimation at the receiver more challenging. Current research focuses on capacity calculation, peak-to-average ratio (PAPR) suppression, and signal detection for non-orthogonal multi-carrier transmission systems, but lacks research on frequency offset estimation for these systems. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a pilot sequence design method and device for a non-orthogonal multi-carrier transmission system, so as to solve the technical problem of how to improve the frequency offset estimation performance.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a pilot sequence design method for a non-orthogonal multi-carrier transmission system, comprising:

[0007] Initializing a non-orthogonal multi-carrier transmission system;

[0008] For an initialized non-orthogonal multi-carrier transmission system, generating a transmit signal;

[0009] Taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel, a received signal is generated;

[0010] Calculate the joint probability density distribution function of the received signal, and take the natural logarithm of the joint probability density distribution function to generate a log-likelihood function;

[0011] Take partial derivatives of the variables in the log-likelihood function and calculate the information matrix;

[0012] The theoretical performance bound of frequency offset estimation is calculated based on the information matrix, and the objective function of pilot optimization is constructed based on the theoretical performance bound.

[0013] The objective function is solved to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system.

[0014] Optionally, the mapping matrix of the transmitted signal is:

[0015]

[0016] Where F(n,m) is the element in the nth row and mth column of the mapping matrix F, M and β are the number of subcarriers and the subcarrier compression factor of the non-orthogonal transmission system, and ρ is the signal oversampling multiple.

[0017] Optionally, the vector of the received vector is:

[0018] y=C(ε)Fb+w

[0019] Where y is the vector of the received signal, F is the mapping matrix of the transmitted signal, C(ε) is the carrier frequency offset matrix, ε is the normalized carrier frequency offset, b is the modulation symbol vector, and w is the noise vector.

[0020] Optionally, the log-likelihood function is:

[0021] g(y;ε)=‖yC(ε)FB‖ 2

[0022] Where ‖·‖ is the norm operation.

[0023] Optionally, the objective function is:

[0024] h(b)=b H Ab

[0025] Where A = F H F, (·) H is the conjugate transpose of the matrix.

[0026] Optionally, solving the objective function to obtain a pilot sequence for the non-orthogonal multi-carrier transmission system includes:

[0027] Perform singular value decomposition on matrix A:

[0028] A=UΓU H

[0029] In the formula, U, Γ, U H All are product matrices;

[0030] By finding the modulation symbol vector b corresponding to the largest singular value max , obtain the maximum value of the objective function;

[0031] The modulation symbol vector b max Output as a pilot sequence.

[0032] In a second aspect, the present invention provides a pilot sequence design device for a non-orthogonal multi-carrier transmission system, comprising:

[0033] An initialization module, used for initializing a non-orthogonal multi-carrier transmission system;

[0034] A transmission signal generating module, configured to generate a transmission signal for an initialized non-orthogonal multi-carrier transmission system;

[0035] A receiving signal generation module is used to generate a receiving signal taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel;

[0036] The log-likelihood function module is used to calculate the joint probability density distribution function of the received signal and take the natural logarithm of the joint probability density distribution function to generate the log-likelihood function;

[0037] The information matrix calculation module is used to obtain partial derivatives of the variables in the log-likelihood function and calculate the information matrix;

[0038] An objective function construction module is used to calculate the theoretical performance bound of frequency offset estimation according to the information matrix and construct the objective function of pilot optimization based on the theoretical performance bound;

[0039] The objective function solving module is used to solve the objective function to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system.

[0040] In a third aspect, the present invention provides an electronic device, including a processor and a storage medium;

[0041] The storage medium is used to store instructions;

[0042] The processor is configured to operate according to the instructions to execute the steps of the above method.

[0043] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a pilot sequence design method and device for a non-orthogonal multi-carrier transmission system. By constructing the sending signal and receiving signal of a non-orthogonal multi-carrier system transmission model, a theoretical performance bound for frequency offset estimation is derived. The objective function of the theoretical performance bound is then solved to obtain an optimal pilot sequence. The optimal pilot sequence calculated by the present invention can achieve better frequency offset estimation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1This is a flowchart of a pilot sequence design method for a non-orthogonal multi-carrier transmission system provided by the first embodiment of the present invention;

[0047] Figure 2 1 is a schematic diagram showing the relationship between the frequency offset estimation performance and the signal-to-noise ratio of the pilot sequence of the present invention under different timing offsets provided in the first embodiment of the present invention;

[0048] Figure 3 1 is a schematic diagram showing the relationship between the pilot sequence frequency offset estimation performance and the normalized frequency offset under different timing offsets provided in the first embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram showing the impact of timing deviation on bit error performance when the frequency domain compression factor is 0.9, provided in the first embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram showing the impact of timing deviation on bit error performance when the frequency domain compression factor is 0.7, provided in the first embodiment of the present invention;

[0051] Figure 6 This is a schematic diagram of the impact of timing deviation on bit error performance when the frequency domain compression factor is 0.5, provided in the first embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0053] Example 1:

[0054] like Figure 1 As shown, an embodiment of the present invention provides a pilot sequence design method for a non-orthogonal multi-carrier transmission system, including:

[0055] 1. Initialize the non-orthogonal multi-carrier transmission system, including initializing parameters such as pilot length, data length, modulation order, and compression factor of non-orthogonal subcarriers.

[0056] 2. For the initialized non-orthogonal multi-carrier transmission system, generating a transmit signal;

[0057] The mapping matrix of the transmitted signal is:

[0058]

[0059] Where F(n,m) is the element in the nth row and mth column of the mapping matrix F, M and β are the number of subcarriers and the subcarrier compression factor of the non-orthogonal transmission system, and ρ is the signal oversampling multiple.

[0060] 3. Taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel, a received signal is generated;

[0061] The vector of received vectors is:

[0062] y=C(ε)Fb+w

[0063] Where y is the vector of the received signal, F is the mapping matrix of the transmitted signal, C(ε) is the carrier frequency offset matrix, ε is the normalized carrier frequency offset, b is the modulation symbol vector, and w is the noise vector.

[0064] 4. Calculate the joint probability density distribution function of the received signal and take the natural logarithm of the joint probability density distribution function to generate the log-likelihood function;

[0065] The log-likelihood function is:

[0066] g(y;ε)=‖yC(ε)Fb‖ 2

[0067] Where ‖·‖ is the norm operation.

[0068] 5. Take partial derivatives of the variables in the log-likelihood function and calculate the information matrix.

[0069] 6. Calculate the theoretical performance bound of frequency offset estimation based on the information matrix, and construct the objective function of pilot optimization based on the theoretical performance bound;

[0070] The objective function is:

[0071] h(b)=b H Ab

[0072] Where A = F H F, (·) H is the conjugate transpose of the matrix.

[0073] 7. Solve the objective function to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system;

[0074] Perform singular value decomposition on matrix A:

[0075] A=UTU H

[0076] In the formula, U, Γ, U H All are product matrices;

[0077] By finding the modulation symbol vector b corresponding to the largest singular value max , obtain the maximum value of the objective function;

[0078] The modulation symbol vector b max Output as a pilot sequence.

[0079] like Figure 2-3 The results show the impact of different timing offsets on frequency offset estimation performance. In the simulations, the timing offsets were set to 0.039T0, 0.063T0, 0.125T0, and 0.156T0, respectively, where T0 is the duration of a symbol. The modulation scheme is Quadrature Phase Shift Keying (QPSK), the total number of subcarriers is 256, and the subcarrier spacing compression factor is 0.5. Compared with traditional M, Gold, and ZC sequences, the proposed pilot sequence significantly outperforms traditional pilot sequences in frequency offset estimation when the timing offset is 0.039T0. However, when the timing offset increases from 0.039T0 to 0.156T0, the frequency offset estimation performance of the proposed algorithm degrades. This is because the temporal misalignment between the transmitted pilot sequence and the local pilot sequence reduces the correlation energy, thus degrading the estimation performance.

[0080] like Figure 4-6 As shown in Figure 2, the bit error performance of a non-orthogonal multi-carrier transmission system (QPSK) under different timing offsets was simulated. The total number of subcarriers was set to 128, the frequency domain compression factors were set to 0.9, 0.7, and 0.5, the duration of a symbol was T0, and the timing offsets were set to 0.078T0, 0.046T0, 0.031T0, and 0.015T0, respectively. Observations show that as the timing offset increases, the bit error performance of the non-orthogonal multi-carrier transmission system gradually deteriorates. This is because the time offset can cause phase rotation in the frequency domain, which changes the phase of the transmitted QPSK symbol and can lead to demodulation errors. Furthermore, even the same timing offset has different effects on transmission systems with different frequency domain compression factors. For example, when the timing deviation is 0.046T0, in order to achieve a bit error performance of 1e-4, for non-orthogonal multi-carrier-QPSK transmission systems with frequency domain compression factors of 0.9, 0.7, and 0.5, the required signal-to-noise ratios are 11.5dB, 13dB, and 21.5dB, respectively.

[0081] In summary, the simulation results show that even under the influence of timing offset, the pilot sequence proposed in the present invention can achieve better frequency offset estimation performance than the traditional M sequence, Gold sequence, and ZC sequence.

[0082] Example 2:

[0083] An embodiment of the present invention provides a pilot sequence design device for a non-orthogonal multi-carrier transmission system, comprising:

[0084] An initialization module, used for initializing a non-orthogonal multi-carrier transmission system;

[0085] A transmission signal generating module, configured to generate a transmission signal for an initialized non-orthogonal multi-carrier transmission system;

[0086] A receiving signal generation module is used to generate a receiving signal taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel;

[0087] The log-likelihood function module is used to calculate the joint probability density distribution function of the received signal and take the natural logarithm of the joint probability density distribution function to generate the log-likelihood function;

[0088] The information matrix calculation module is used to obtain partial derivatives of the variables in the log-likelihood function and calculate the information matrix;

[0089] An objective function construction module is used to calculate the theoretical performance bound of frequency offset estimation according to the information matrix and construct the objective function of pilot optimization based on the theoretical performance bound;

[0090] The objective function solving module is used to solve the objective function to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system.

[0091] Example 3:

[0092] Based on the first embodiment, the present invention provides an electronic device including a processor and a storage medium;

[0093] The storage medium is used to store instructions;

[0094] The processor is configured to operate according to the instructions to execute the steps of the above method.

[0095] Example 4:

[0096] Based on the first embodiment, the embodiment of the present invention provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the above method are implemented.

[0097] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0098] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0099] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0100] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pilot sequence design method for a non-orthogonal multi-carrier transmission system, characterized in that: include: Initializing a non-orthogonal multi-carrier transmission system; For the initialized non-orthogonal multi-carrier transmission system, a transmission signal is generated; the mapping matrix of the transmission signal is: Where F(n,m) is the element in the nth row and mth column of the mapping matrix F, M and β are the number of subcarriers and the subcarrier compression factor of the non-orthogonal transmission system, and ρ is the multiple of signal oversampling; Taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel, a received signal is generated; Calculate the joint probability density distribution function of the received signal, and take the natural logarithm of the joint probability density distribution function to generate a log-likelihood function; Take partial derivatives of the variables in the log-likelihood function and calculate the information matrix; The theoretical performance bound of frequency offset estimation is calculated based on the information matrix, and the objective function of pilot optimization is constructed based on the theoretical performance bound. The objective function is solved to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system.

2. The pilot sequence design method for a non-orthogonal multi-carrier transmission system according to claim 1, wherein: The vector of the received signal is: y=C(ε)Fb+w Where y is the vector of the received signal, F is the mapping matrix of the transmitted signal, C(ε) is the carrier frequency offset matrix, ε is the normalized carrier frequency offset, b is the modulation symbol vector, and w is the noise vector.

3. The pilot sequence design method for a non-orthogonal multi-carrier transmission system according to claim 2, wherein: The log-likelihood function is: g(y;ε)=‖yC(ε)Fb‖ 2 Where ‖·‖ is the norm operation.

4. The pilot sequence design method for a non-orthogonal multi-carrier transmission system according to claim 3, wherein: The objective function is: h(b)=b H Ab Where A = F H F, (·) H is the conjugate transpose of the matrix.

5. The pilot sequence design method for a non-orthogonal multi-carrier transmission system according to claim 4, wherein: Solving the objective function to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system includes: Perform singular value decomposition on matrix A: A=UΓU H In the formula, U, Γ, U H All are product matrices; By finding the modulation symbol vector b corresponding to the largest singular value max , obtain the maximum value of the objective function; The modulation symbol vector b max Output as a pilot sequence.

6. A pilot sequence design device for a non-orthogonal multi-carrier transmission system, characterized in that: include: An initialization module, used for initializing a non-orthogonal multi-carrier transmission system; The transmission signal generation module is used to generate a transmission signal for the initialized non-orthogonal multi-carrier transmission system; the mapping matrix of the transmission signal is: Where F(n,m) is the element in the nth row and mth column of the mapping matrix F, M and β are the number of subcarriers and the subcarrier compression factor of the non-orthogonal transmission system, and ρ is the multiple of signal oversampling; A receiving signal generation module is used to generate a receiving signal taking into account the influence of noise and carrier frequency deviation on the transmitted signal when passing through the wireless channel; The log-likelihood function module is used to calculate the joint probability density distribution function of the received signal and take the natural logarithm of the joint probability density distribution function to generate the log-likelihood function; The information matrix calculation module is used to obtain partial derivatives of the variables in the log-likelihood function and calculate the information matrix; An objective function construction module is used to calculate the theoretical performance bound of frequency offset estimation according to the information matrix and construct the objective function of pilot optimization based on the theoretical performance bound; The objective function solving module is used to solve the objective function to obtain the pilot sequence of the non-orthogonal multi-carrier transmission system.

7. An electronic device, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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