Power distribution transmission method and device under OCDM frequency selection channel

Abstract

The invention provides a power distribution transmission method and device under an OCDM frequency selection channel, and the method comprises the steps: converting a time domain signal into a frequency domain through a discrete Fourier transform matrix at a transmitting end, generating a power distribution matrix through combining channel state information and adopting a water injection algorithm, and carrying out the dynamic power precoding of a frequency domain subcarrier; generating a time domain OCDM signal through an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, adding a cyclic prefix, and transmitting the time domain OCDM signal; after a receiving end is subjected to prefix removal, a discrete Fourier transform matrix is converted into a frequency domain, a frequency domain equalizer is designed on the basis of a minimum mean square error criterion by utilizing channel diagonalization characteristics, signals are equalized in combination with transmitting power information, and finally time domain information is recovered through an inverse discrete Fourier transform matrix; therefore, the problem of traditional power distribution failure caused by OCDM channel energy dispersion is solved, and through receiving and transmitting joint optimization, diversity gain is fully mined, frequency selective channel fading is adaptively matched, the anti-interference and anti-multipath capabilities of the system are improved, and the spectrum efficiency and the transmission performance are maximized.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a power allocation transmission method under OCDM frequency-selective channel, a power allocation transmission device under OCDM frequency-selective channel, a computer-readable storage medium, and a computer device. Background Technology

[0002] In linear time-invariant (LTI) multipath channels, traditional orthogonal frequency division multiplexing (OFDM), while employing a water-filling method to allocate subchannel power and maximize frequency-selective channel capacity, still has fundamental limitations: it is highly sensitive to carrier frequency offset and fails to effectively utilize channel diversity gain. Orthogonal chirp division multiplexing (OCDM) offers superior anti-interference performance, particularly robust to interference caused by insufficient guard intervals. To fully utilize its anti-interference capabilities, an effective transmit power allocation strategy is crucial. Current solutions primarily focus on equalizer design itself, failing to adequately consider the inherent relationship and joint optimization between channel characteristics and receiver equalizers (such as the minimum mean square error (MMSE) criterion).

[0003] OCDM technology replaces the Fourier transform kernel in traditional OFDM with a chirped transform kernel, inherently giving it stronger Doppler (carrier frequency offset) tolerance and the ability to convert the energy dissipation of the channel response in the time-frequency domain into full diversity gain, resulting in significant theoretical performance advantages. However, when OCDM is applied to practical frequency-selective channels, its unique signal structure also brings new challenges. Existing technologies have the following main drawbacks: (1) Channel energy dispersion causes traditional power allocation algorithms to fail: Unlike the near-flat fading experienced by traditional OFDM subcarriers, in the fractional Fourier domain, the energy of a single symbol in an OCDM signal is dispersed across all components of the domain. This inherent "channel dispersion" effect destroys the independence between subcarriers, making it impossible to directly apply the subcarrier power allocation scheme based on the "water-filling principle" in OFDM systems to OCDM systems. Existing methods lack a power allocation theory that can effectively address this channel energy dispersion characteristic, resulting in a mismatch in the power resource configuration at the transmitter and an inability to maximize the utilization of available power resources.

[0004] (2) Diversity gain is not fully exploited through joint optimization: Although the diffusion characteristics of OCDM can be converted into full diversity gain, existing receiver designs (such as MMSE equalization) and transmitter power allocation are often designed separately. This fragmented design mode fails to establish a synergistic optimization relationship between transmit power and receiver equalization, and cannot actively and adaptively shape the signal distribution in the diffusion channel through joint design, thus limiting the extent to which the system can convert theoretical diversity gain into actual bit error rate performance improvement.

[0005] (3) The system design failed to fully leverage the inherent advantages of OCDM: Existing research on applying OCDM to frequency-selective channels often focuses on its anti-frequency offset capability or only improves the equalization algorithm at the receiver end, while ignoring the key degree of freedom of power allocation at the transmitter end. A unified joint optimization framework for transmit power-receive equalization has not been constructed to systematically leverage the anti-frequency offset advantage of OCDM and explore its full diversity potential in frequency-selective channels, resulting in the overall spectral efficiency and robustness of the system not reaching the optimal level. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in the aforementioned technologies. To this end, one objective of this invention is to propose a power allocation transmission method under OCDM frequency-selective channels, which improves the transmission performance of OCDM systems under frequency-selective fading channels through the joint design of power allocation and equalizers.

[0007] A second objective of this invention is to provide a computer-readable storage medium.

[0008] The third objective of this invention is to provide a computer device.

[0009] The fourth objective of this invention is to provide a power distribution transmission device under OCDM frequency-selective channel.

[0010] To achieve the above objectives, a first aspect of the present invention proposes a power allocation transmission method under an OCDM frequency-selective channel. The method includes the following steps: obtaining the original symbol sequence carrying transmission information; converting the original symbol sequence to the frequency domain using a discrete Fourier transform matrix, performing dynamic power precoding in the frequency domain using a power allocation matrix, and converting the power-allocated frequency domain signal to the time domain using an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and adding a cyclic prefix to obtain a transmitted signal; transmitting the transmitted signal through a frequency-selective channel according to the corresponding allocated power; receiving the transmitted signal, removing the cyclic prefix, and converting it to the frequency domain using a discrete Fourier transform matrix, and obtaining a channel frequency response matrix based on the channel time-domain response matrix; designing a frequency domain equalizer based on the channel frequency response matrix and the power allocation matrix using the minimum mean square error criterion to simultaneously eliminate channel distortion and transmitter power weighting effects, and converting the equalized frequency domain signal to the time domain using an inverse discrete Fourier transform matrix to demodulate and recover the original symbol sequence.

[0011] The power allocation transmission method under frequency-selective fading channel proposed in this invention has the advantage of improving the transmission performance of OCDM system under frequency-selective fading channel by combining power allocation and equalizer design based on the minimum mean square error criterion.

[0012] In addition, the power allocation transmission method under OCDM frequency-selective channel proposed in the above embodiments of the present invention may also have the following additional technical features: Optionally, the power-divided frequency domain signal can be converted to the time domain according to the following formula:

[0013] in, To convert the power-divided frequency domain signal to the time domain to obtain the time-domain CP-OCDM signal, This represents the inverse discrete Fresnel transformation matrix of size N. This represents the inverse discrete Fourier transform matrix of size N. This represents the power allocation matrix, which is an N×N diagonal matrix with diagonal elements. The power allocation coefficients for each subcarrier are calculated using channel state information and the minimum mean square error criterion. This represents the original symbol sequence after constellation mapping.

[0014] Alternatively, the discrete Fresnel transformation matrix can be obtained according to the following formula:

[0015] in, Let m represent a discrete Fresnel transformation matrix of size N, where m represents the element in the m-th row of the discrete Fresnel transformation matrix. represents the nth column element of the matrix, and j represents the imaginary unit.

[0016] Alternatively, the channel frequency response matrix can be obtained according to the following formula:

[0017] in, Represents the channel frequency response matrix. Let N represent a normalized orthogonal discrete Fourier transform matrix of size N. This represents the channel time-domain response matrix, which is the time-domain channel convolution matrix obtained by constructing the Toeplitz matrix.

[0018] Alternatively, the equalized frequency domain signal can be obtained according to the following formula:

[0019] in, This represents the equalized frequency domain signal. Let k be a diagonal matrix, and let k be the diagonal element. For the coefficients of a single-tap equalizer. Let this be a diagonal matrix, with its diagonal elements... It is the discrete Fresnel transformation matrix The eigenvalues, i.e., the Zadoff-Chu sequence, This represents the additive noise vector at the receiver. It follows a zero-mean Gaussian distribution and has a power of 1. White noise, Represents the identity matrix.

[0020] Alternatively, the diagonal elements of the diagonal matrix can be obtained according to the following formula:

[0021] in, This represents the diagonal element of the k-th subcarrier.

[0022] To achieve the above objectives, a second aspect of the present invention provides a computer-readable storage medium storing a power allocation transmission program under an OCDM frequency-selective channel, which, when executed by a processor, implements the power allocation transmission method under an OCDM frequency-selective channel as described above.

[0023] To achieve the above objectives, a third aspect of the present invention provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the power allocation transmission method under the OCDM frequency-selective channel as described above.

[0024] To achieve the above objectives, a fourth aspect of the present invention proposes a power allocation transmission device under an OCDM frequency-selective channel, comprising: an acquisition module for acquiring the original symbol sequence carrying transmission information; an encoding module for converting the original symbol sequence carrying transmission information to the frequency domain using a discrete Fourier transform matrix, performing dynamic power precoding in the frequency domain using a power allocation matrix, and converting the power-allocated frequency domain signal to the time domain using an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and adding a cyclic prefix to obtain a transmitted signal; a transmission module for transmitting the transmitted signal through a frequency-selective channel according to the corresponding allocated power; a conversion module for receiving the transmitted signal, removing the cyclic prefix, converting it to the frequency domain using a discrete Fourier transform matrix, and obtaining a channel frequency response matrix based on the channel time domain response matrix; and an equalization decoding module for designing a frequency domain equalizer based on the channel frequency response matrix and the power allocation matrix using a minimum mean square error criterion to simultaneously eliminate channel distortion and transmitter power weighting effects, and converting the equalized frequency domain signal to the time domain using an inverse discrete Fourier transform matrix to demodulate and recover the original symbol sequence. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the power allocation transmission method under OCDM frequency-selective channel according to an embodiment of the present invention. Figure 2 This is a schematic diagram of an OCDM transceiver system with power distribution according to an embodiment of the present invention; Figure 3 This is a schematic diagram of channel frequency response transformation according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the water injection power allocation algorithm of an OCDM according to an embodiment of the present invention; Figure 5 This is a diagram showing the correspondence between channel and noise conditions and subcarrier power allocation according to an embodiment of the present invention; Figure 6 This is a block diagram of a power distribution transmission device under an OCDM frequency-selective channel according to an embodiment of the present invention. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0028] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0029] It should be noted that the power allocation transmission method under the OCDM frequency-selective channel in this embodiment of the invention aims to utilize partial channel state information (CSI) from the transmitter to achieve adaptive power adjustment through a minimum mean square error receiver, thereby reducing power backoff and releasing more transmission power. Through the coordinated design of the transmitter power allocation matrix and the receiver Fresnel domain equalizer, the signal interference problem caused by the superposition of channel distortion and precoding effects is solved. This is the first time that a power allocation strategy combining the channel and equalizer receiver has been introduced into the CP-OCDM system, while remaining compatible with the classic OFDM power allocation framework. Figure 2 As shown, a cyclic transmission matrix is ​​constructed by concatenating the discrete Fourier transform matrix and the power allocation matrix to map symbols to a cyclic pulse sequence, thereby achieving dynamic power allocation based on the minimum mean square error criterion. This mechanism optimizes the time-domain pulse waveform and equalizes the frequency-domain noise distribution by adjusting the power matrix parameters. The power allocation matrix performs key functions in the frequency domain: its diagonal elements rely on partial channel state information obtained from the transmitter to perform inverse gain equalization and a water-filling-like power allocation strategy on the frequency subbands of the linear frequency modulated signal using the minimum mean square error criterion. Figure 4 As shown, from the precoding matrix The given emission matrix is ​​constructed as a cyclic matrix (where, The DFT matrix, (It is its conjugate transpose), which ensures that the energy of the time-domain pulse is uniformly distributed within the symbol period by mapping the power allocation logic in the frequency domain to the waveform optimization process of the time-domain cyclic pulse sequence. At the same time, by utilizing the diagonalization capability of the channel matrix by DFT, this power allocation mechanism can indirectly optimize the anti-multipath characteristics of the time-domain pulse, which is significantly different from the mode of OFDM that directly implements power allocation on independent subcarriers.

[0030] refer to Figure 1 As shown, the power allocation transmission method under the OCDM frequency-selective channel of this invention includes the following steps: S101, Obtain the original symbol sequence carrying the transmitted information.

[0031] As an example, the original symbol sequence is a digital signal form of the information bit stream after encoding and modulation. It is the input signal of the OCDM system transmitter, obtained by constellation mapping of the user-input data to be transmitted.

[0032] S102 uses a discrete Fourier transform matrix to convert the original symbol sequence carrying the transmitted information to the frequency domain, performs dynamic power precoding in the frequency domain using a power allocation matrix, and uses an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix to convert the power-allocated frequency domain signal to the time domain, and adds a cyclic prefix to obtain the transmitted signal.

[0033] In other words, at the transmitting end, the symbol sequence carrying information is first transformed to the frequency domain through an N-point Discrete Fourier Transform (DFT) matrix. Then, dynamic power precoding is performed in the frequency domain through a power allocation diagonal matrix. The power allocation matrix is ​​dynamically generated based on channel state information and noise statistics, according to a water-filling algorithm, to achieve optimal power allocation on the frequency domain subcarriers. After power allocation, the frequency domain signal is sequentially processed by an N-point Discrete Fourier Transform (IDFT) matrix and an Inverse Discrete Fresnel Transform (IDFnT) matrix to generate a time-domain CP-OCDM signal, and a cyclic prefix is ​​added to form the final transmitted waveform. This process optimizes the time-domain pulse waveform by adjusting the power matrix parameters, so that the signal energy is concentrated in the time domain, while suppressing frequency domain noise interference.

[0034] As a specific embodiment, in order to generate a CP-OCDM signal, the following is used: Figure 1 The transmission scheme shown transmits symbol vectors. (At this point, the symbol is a 4QAM symbol mapped by a constellation.) After precoding the energy distribution, a time-domain signal is generated using IDFnT:

[0035] in, To convert the power-divided frequency domain signal to the time domain to obtain the time-domain CP-OCDM signal, This represents the inverse discrete Fresnel transformation matrix of size N. This represents the inverse discrete Fourier transform matrix of size N. This represents the power allocation matrix, which is an N×N diagonal matrix with diagonal elements. The power allocation coefficients for each subcarrier are calculated using channel state information and the minimum mean square error criterion. This represents the original symbol sequence (of length N) after constellation mapping.

[0036] As an example, the discrete Fresnel transformation matrix is ​​obtained according to the following formula:

[0037] in, Let m represent a discrete Fresnel transformation matrix of size N, where m represents the element in the m-th row of the discrete Fresnel transformation matrix. represents the nth column element of the matrix, and j represents the imaginary unit.

[0038] In other words, when N is even, When N is odd, .

[0039] S103 transmits the transmitted signal through a frequency-selective channel according to the corresponding allocated power.

[0040] In other words, the diagonal elements of the power allocation matrix (i.e., power allocation coefficients) directly affect the frequency domain sub-bands, distributing the total transmit power to each sub-band according to an optimized strategy. For example, a higher power coefficient is allocated to sub-bands with high channel gain to ensure that the signal in that sub-band can resist stronger fading during transmission.

[0041] S104 receives the transmitted signal, removes the cyclic prefix, and then transforms it to the frequency domain using a discrete Fourier transform matrix, and obtains the channel frequency response matrix based on the channel time domain response matrix.

[0042] In other words, at the receiving end, after removing the cyclic prefix, the received signal is converted to the frequency domain using an N-point DFT matrix, and the channel time-domain response matrix is ​​diagonalized using the DFT matrix to obtain the channel frequency response matrix, providing channel state information for subsequent equalization.

[0043] It should be noted that, by leveraging the diagonalization property in the frequency domain, the multidimensional equalization problem is simplified to scalar operations on frequency subbands, achieving low-complexity equalization. Through the cascaded design of the power allocation matrix and DFT, in a frequency-selective channel environment, it is possible to achieve both optimal bit rate and signal-to-noise ratio (SNR) for transmitted symbols, demonstrating the channel adaptability of a multi-carrier system. A frequency-selective Rayleigh fading channel is used to simulate the multipath propagation environment of communication. Since a cyclic prefix is ​​inserted at the transmitter and removed at the receiver, the channel is given by a cyclic matrix, with each column representing a composite channel impulse response. The diagonal matrix is ​​obtained by diagonalizing the DFT of the composite channel impulse response, which is equivalent to the frequency response of the composite channel at different subcarrier frequencies; the time-domain channel convolution matrix is ​​obtained by constructing the Toeplitz matrix. Furthermore, the equivalent channel matrix of the cyclic prefix system is derived.

[0044] Reviewing the DFT matrix diagonalization of any cyclic matrix, such as Figure 3 As shown, the channel frequency response matrix is:

[0045] in, Represents the channel frequency response matrix. Let N represent a normalized orthogonal discrete Fourier transform matrix of size N. The time-domain channel convolution matrix (channel time-domain response matrix) is obtained by constructing the Toeplitz matrix, representing the composite channel generated by the cascading of the analog transmission chain and the physical channel.

[0046] S105. Based on the channel frequency response matrix and power allocation matrix, a frequency domain equalizer is designed using the minimum mean square error criterion to simultaneously eliminate channel distortion and transmitter power weighting effects. An inverse discrete Fourier transform matrix is ​​then used to convert the equalized frequency domain signal to the time domain to demodulate and recover the original symbol sequence.

[0047] In other words, at the receiver, based on the joint information of the channel frequency response matrix and the transmitter power allocation matrix, a frequency domain equalizer is designed using the MMSE criterion to simultaneously eliminate channel distortion and transmitter power weighting effects; the equalized signal is converted to the time domain by an N-point inverse discrete Fourier transform matrix, and finally the original information symbols are recovered by demodulation.

[0048] As an example, the received signal vector through the channel It can be written as:

[0049] in, It is the additive noise vector at the receiver, assumed to follow a zero-mean Gaussian distribution and be power-law 1. The white noise; after removing the cyclic prefix, unlike directly performing DFnT, it needs to be transformed to the frequency domain using DFT, and the identity is used. This can be further deduced as:

[0050] in, It is a diagonal matrix, and its diagonal elements are... It is a DFnT matrix The eigenvalues, i.e., the Zadoff-Chu sequence (with a modulus of 1), are expressed in phase as follows:

[0051] Based on the channel diagonalization transformation of the channel frequency response matrix, the received signal can be simplified to:

[0052] The estimated signal vector at the receiver is given by the following equation:

[0053] Before compensating for the channel frequency response (CFR), the matrix is ​​first eliminated. The introduced phase. Among them, Given a diagonal matrix, its k-th diagonal element... These are the coefficients of the single-tap equalizer. Finally, the transmitted information is recovered using the inverse discrete Fourier transform (IDFT).

[0054] As a specific example, in OCDM power allocation with channel information and MMSE equalization: First, a joint optimization problem is constructed with the goal of minimizing the total mean square error of the system: the power allocation vector at the transmitter and the MMSE equalizer coefficients at the receiver are used as joint optimization variables to form a unified optimization objective function constrained by the total power.

[0055] Specifically: (1-1) The goal of the problem is to find the optimal power allocation matrix. To maximize at constant transmit power Given the subcarrier signal-to-noise ratio, the constraints and coefficients for the transmit power are also considered. The value is related to, and can be represented as:

[0056] (1-2) The power of the transmitted symbol x(n) included in this constraint is determined by... Given the coefficients It is only responsible for allocating transmit power across subcarriers. The following shows the derived OCDM soft water-filling (OCDM-SWF-MMSE) method for joint channel and MMSE receiver. Considering the MMSE receiver and channel together, the estimated signal vector at the MMSE receiver is given by the following equation:

[0057] in, It is a receiver with a joint channel and equalizer design. Due to the joint design, the precoding matrix contains... This eliminates the need for multiplication at the receiving end. .

[0058] The use of the MMSE criterion (1-3) is reasonable because minimizing the mean square error (MSE) leads to maximizing the decision signal-to-noise ratio (SNR), which is inversely proportional to the bit error rate (BER). Therefore, by minimizing the MSE, a reduction in BER should be expected. The optimal MMSE solution, given by the Wiener solution, is obtained through the formula for the joint optimal power allocation design of the channel and equalizer:

[0059] in, It is receiving signals The autocorrelation matrix, It is receiving signals and desired signal vector The cross-correlation matrix between them Each column corresponds to the cross-correlation vector between the corresponding elements of the received signal and the desired signal.

[0060] (1-4) can be used to determine the correlation matrix Written as:

[0061] Among them, the fact that the symbol sent is iid has already been used, that is... .

[0062] (1-5) Due to noise and signal They are independent, and the cross-correlation vector is given by the following formula:

[0063] (1-5) Substituting the autocorrelation matrix (1-4) and cross-correlation matrix (1-5) into the estimated signal (1-3) at the MMSE receiver, the MMSE equalizer can be calculated, given by the following formula:

[0064] (1-7) Note that the equalizer depends on the channel (through its frequency response). ) and transmit pulse And the Zadoff-Chu sequence of the Fresnel matrix. By substituting into (1-5) The sign of the estimate is given by the following formula:

[0065] in, , (because The existence of and (They are all circular matrices).

[0066] (1-8) From the above equation, the desired signal power and the equivalent noise and inter-symbol interference (ISI) power can be calculated. First, only the effect of the desired signal is considered. and its estimate The gain between them is determined by the matrix The diagonal elements are given, and the matrix It is a cyclic matrix. Therefore, All diagonal elements are equal. Then, the power of the signal required at any given time is given by the following formula:

[0067] in, It is the power allocated to the i-th subcarrier, and It is the square of the channel gain at subcarrier i.

[0068] (1-9) Then calculate the power of the estimated signal ( ), which is defined as the power of the desired signal ( ) plus ISI's power ( The power of the estimated signal is given by the diagonal elements of the covariance matrix of the estimated signal. Since the covariance matrix of the estimated signal is also a cyclic matrix, it is given by the following equation:

[0069] (1-10) Finally, the power of the noise that corrupts the desired signal is calculated, given by the diagonal elements of the covariance matrix of the equivalent noise. The equivalent noise covariance matrix can be written as a cyclic matrix. Therefore, the variance of the equivalent noise can be expressed as follows:

[0070] (1-11) Once the quantity is defined and Therefore, the signal-to-interference-plus-noise ratio (SINR) of the estimated signal can be expressed as:

[0071]

[0072] (1-12) The equivalent decision SNR of the MMSE receiver is given by the following formula:

[0073] (1-13) It can be directly seen that maximizing the SNR of the estimated symbols after maximizing the MMSE receiver is equivalent to maximizing the SINR of these symbols. Therefore, the constraint problem can be transformed into a constraint maximization problem of finding the SINR, that is:

[0074] Next, the joint optimization problem of power allocation and MMSE equalization is solved: an iterative algorithm (similar to the water-filling algorithm) from optimization theory is used to solve the above problem. In each iteration, the equalizer coefficients are optimized while the power allocation is fixed, and then the power allocation is optimized while the equalizer coefficients are fixed, until the algorithm converges, finally obtaining the optimal power allocation scheme and the corresponding MMSE equalizer coefficients.

[0075] Specifically: (2-1) This optimal solution problem can be solved using Lagrange multipliers. The Lagrange cost function is given by the following equation:

[0076] in, It is a Lagrange multiplier.

[0077] (2-2) and the optimal power can be obtained through its for By setting the derivative to zero, and after processing, the expression can be rewritten as:

[0078] Where, if a ≥ 0, then It equals 'a', otherwise it equals '0'.

[0079] (2-3) Calculation The value of is determined to comply with the constraint of constant transmit power:

[0080] Equation (2-4) (2-3) shows the optimal power Following the principle of water injection, these optimal values ​​can be achieved by adjusting the water level. To satisfy the power constraints, the optimal power is then obtained by calculating (2-3). It should be emphasized that since the power being processed is exponential, therefore... The values ​​must all be non-negative, which explains the operator. The use of.

[0081] (2-5) If we assume that all terms between the parentheses in (2-3) are non-negative, i.e., all subcarriers are used for transmission, then we can analytically obtain The value is:

[0082] (2-6) The optimal power reading is:

[0083] (2-7) However, if some If it is negative, then by discarding it. The subcarriers are then calculated again for this new subset of subcarriers (2-6), and this process is repeated until all powers are non-negative, such as... Figure 5 As shown, the final subset of subcarriers used is called Ω. It is worth emphasizing that the two summations in (2-6) are now performed on the subset Ω. Since this process is similar to the traditional water-filling algorithm, this algorithm is named the OCDM Soft Water-Filling Power Allocation MMSE (OCDM-SWF-MMSE) algorithm.

[0084] Finally, adaptive transmission based on channel state information is achieved: the optimal power allocation scheme is applied to different subcarriers at the OCDM transmitter to achieve adaptive power loading; at the same time, the corresponding optimal MMSE equalizer is configured at the receiver to complete the joint optimization processing of the received signal, thereby effectively overcoming frequency selective fading and improving the overall system performance.

[0085] Specifically: (3-1) By substituting the optimal power (1-11) into (2-6), the optimal decision SINR of the MMSE receiver is obtained as:

[0086] here yes The base number.

[0087] (3-2) Then the optimal SNR corresponding to MMSE can be obtained:

[0088] (3-3) Therefore, after some operations, the achievable bit rate per transmit symbol of the MMSE receiver scheme is given by the following equation:

[0089] (3-4) Unlike OFDM, which can directly allocate power to subcarriers, OCDM constructs a cyclic transmission matrix using a DFT matrix. After diagonalizing the channel matrix, the SNR of a subcarrier needs to be characterized by a global noise enhancement term or the mean SNR (e.g., a weighted average in MMSE receivers), rather than by the characteristics of individual subcarriers. This fundamental difference dictates that OCDM power allocation relies on the frequency domain diagonalization of the cyclic matrix. After cascading the power allocation matrix and DFT to generate the transmission matrix, OCDM indirectly optimizes the energy distribution of the time-domain cyclic pulse by maximizing the signal-to-noise ratio through the principle of minimum mean square error (MMSE), balancing the reachable bit rate and channel adaptability. At this point, the OCDM-SWF-MMSE algorithm can obtain the optimal power allocation scheme and the associated maximum reachable bit rate.

[0090] In summary, the power allocation transmission method under the OCDM frequency-selective channel according to the embodiments of the present invention effectively overcomes inter-symbol interference caused by multipath effects by establishing a unified optimization model, significantly improving the bit error rate performance of the system under frequency-selective fading channels; by jointly optimizing the transmitter power allocation and the receiver equalizer, the end-to-end transmission efficiency of the system is maximized, significantly enhancing the anti-interference and anti-multipath fading capabilities of the OCDM system in frequency-selective channels; and by optimizing the power distribution of each subcarrier of the OCDM in real time, accurate matching of the fading characteristics of the frequency-selective channel is achieved, thereby maximizing the overall spectral efficiency of the system while ensuring fairness.

[0091] In addition, the present invention also proposes a computer-readable storage medium storing a power allocation transmission program under OCDM frequency-selective channel, which, when executed by a processor, implements the power allocation transmission method under OCDM frequency-selective channel as described above.

[0092] In addition, this invention also proposes a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the power allocation transmission method under the OCDM frequency-selective channel as described above.

[0093] Figure 6 This is a block diagram of a power distribution transmission apparatus under an OCDM frequency-selective channel according to an embodiment of the present invention. Figure 6 As shown, the device includes: an acquisition module 10, an encoding module 20, a transmission module 30, a conversion module 40, and an equalization decoding module 50; The module comprises the following components: an acquisition module 10 for acquiring the original symbol sequence carrying the transmission information; an encoding module 20 for converting the original symbol sequence carrying the transmission information to the frequency domain using a discrete Fourier transform matrix, performing dynamic power precoding in the frequency domain using a power allocation matrix, converting the power-allocated frequency domain signal to the time domain using an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and adding a cyclic prefix to obtain the transmitted signal; a transmission module 30 for transmitting the transmitted signal through a frequency-selective channel according to the corresponding allocated power; a conversion module 40 for receiving the transmitted signal, removing the cyclic prefix, converting it to the frequency domain using a discrete Fourier transform matrix, and obtaining the channel frequency response matrix based on the channel time domain response matrix; and an equalization decoding module 50 for designing a frequency domain equalizer based on the channel frequency response matrix and the power allocation matrix using the minimum mean square error criterion to simultaneously eliminate channel distortion and the power weighting effect at the transmitting end, and converting the equalized frequency domain signal to the time domain using an inverse discrete Fourier transform matrix to demodulate and recover the original symbol sequence.

[0094] It should be noted that the foregoing explanation of the embodiment of the power allocation transmission method under OCDM frequency-selective channel also applies to the power allocation transmission device under OCDM frequency-selective channel in this embodiment, and will not be repeated here.

[0095] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0100] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0101] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0102] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0103] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0104] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0105] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0106] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A power allocation transmission method under an OCDM frequency-selective channel, characterized in that, Includes the following steps: Obtain the original symbol sequence carrying the transmitted information; The original symbol sequence carrying the transmitted information is converted to the frequency domain using a discrete Fourier transform matrix, and dynamic power precoding is performed in the frequency domain using a power allocation matrix. The power-allocated frequency domain signal is converted to the time domain using an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and a cyclic prefix is ​​added to obtain the transmitted signal. The transmitted signal is transmitted through a frequency-selective channel according to the corresponding allocated power. The transmitted signal is received, and after removing the cyclic prefix, it is transformed to the frequency domain using a discrete Fourier transform matrix, and the channel frequency response matrix is ​​obtained based on the channel time domain response matrix; Based on the channel frequency response matrix and power allocation matrix, a frequency domain equalizer is designed using the minimum mean square error criterion to simultaneously eliminate channel distortion and transmitter power weighting effects. The inverse discrete Fourier transform matrix is ​​then used to convert the equalized frequency domain signal to the time domain to demodulate and recover the original symbol sequence.

2. The power allocation transmission method under OCDM frequency-selective channel as described in claim 1, characterized in that, The frequency domain signal after power allocation is converted to the time domain using the following formula: in, To convert the power-divided frequency domain signal to the time domain to obtain the time-domain CP-OCDM signal, This represents the inverse discrete Fresnel transformation matrix of size N. This represents the inverse discrete Fourier transform matrix of size N. This represents the power allocation matrix, which is an N×N diagonal matrix with diagonal elements. The power allocation coefficients for each subcarrier are calculated using channel state information and the minimum mean square error criterion. This represents the original symbol sequence after constellation mapping.

3. The power allocation transmission method under OCDM frequency-selective channel as described in claim 2, characterized in that, The discrete Fresnel transformation matrix can be obtained using the following formula: in, Let m represent a discrete Fresnel transformation matrix of size N, where m represents the element in the m-th row of the discrete Fresnel transformation matrix. represents the nth column element of the matrix, and j represents the imaginary unit.

4. The power allocation transmission method under OCDM frequency-selective channel as described in claim 3, characterized in that, The channel frequency response matrix is ​​obtained using the following formula: in, Represents the channel frequency response matrix. Let N represent a normalized orthogonal discrete Fourier transform matrix of size N. This represents the channel time-domain response matrix, which is the time-domain channel convolution matrix obtained by constructing the Toeplitz matrix.

5. The power allocation transmission method under OCDM frequency-selective channel as described in claim 4, characterized in that, The equalized frequency domain signal is obtained using the following formula: in, This represents the equalized frequency domain signal. Let k be a diagonal matrix, and let k be the diagonal element. For the coefficients of a single-tap equalizer. Let this be a diagonal matrix, with its diagonal elements... It is the discrete Fresnel transformation matrix The eigenvalues, i.e., the Zadoff-Chu sequence, This represents the additive noise vector at the receiving end. It follows a zero-mean Gaussian distribution and has a power of 0. White noise, Represents the identity matrix.

6. The power allocation transmission method under OCDM frequency-selective channel as described in claim 5, characterized in that, The diagonal elements of a diagonal matrix can be obtained using the following formula: in, This represents the diagonal element of the k-th subcarrier.

7. A computer-readable storage medium, characterized in that, It stores a power allocation transmission program under OCDM frequency-selective channel, which, when executed by the processor, implements the power allocation transmission method under OCDM frequency-selective channel as described in any one of claims 1-6.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the power allocation transmission method under the OCDM frequency-selective channel as described in any one of claims 1-6.

9. A power distribution transmission device under an OCDM frequency-selective channel, characterized in that, include: The acquisition module is used to acquire the original symbol sequence carrying the transmitted information; The encoding module is used to convert the original symbol sequence carrying the transmission information to the frequency domain using a discrete Fourier transform matrix, perform dynamic power precoding in the frequency domain using a power allocation matrix, and convert the power-allocated frequency domain signal to the time domain using an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and add a cyclic prefix to obtain the transmitted signal. The transmission module is used to transmit the transmitted signal through a frequency-selective channel according to the corresponding allocated power. The conversion module is used to receive the transmitted signal, remove the cyclic prefix, convert it to the frequency domain using a discrete Fourier transform matrix, and obtain the channel frequency response matrix based on the channel time domain response matrix. The equalization decoding module is used to design a frequency domain equalizer based on the channel frequency response matrix and power allocation matrix using the minimum mean square error criterion, so as to simultaneously eliminate channel distortion and transmitter power weighting effect, and use the inverse discrete Fourier transform matrix to convert the equalized frequency domain signal to the time domain to demodulate and recover the original symbol sequence.

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