CN-122002298-A - Power distribution transmission method and device under OCDM frequency selective channel

CN122002298ACN 122002298 ACN122002298 ACN 122002298ACN-122002298-A

Abstract

The invention provides a power distribution transmission method and a device under an OCDM frequency selection channel, wherein the method comprises the steps of converting a time domain signal into a frequency domain through a discrete Fourier transform matrix at a transmitting end, generating a power distribution matrix by combining channel state information and adopting a water injection algorithm, pre-coding dynamic power of frequency domain subcarriers, generating the time domain OCDM signal through an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, adding cyclic prefix for transmission, converting the discrete Fourier transform matrix into the frequency domain after a receiving end removes the prefix, utilizing the diagonalization characteristic of the channel, designing a frequency domain equalizer based on a minimum mean square error criterion, combining transmitting power information equalization signals and finally recovering time domain information through the inverse discrete Fourier transform matrix, thereby solving the problem of failure of traditional power distribution caused by OCDM channel energy dispersion, fully excavating diversity gain through transmit-receive combined optimization, self-adaptively matching frequency selective channel fading, improving the anti-interference and anti-multipath capacity of the system, and maximizing the frequency spectrum efficiency and the transmission performance.

Inventors

ZHANG RONGXIN
WANG YUEKUN
LIU JINGYI
WEI WENJIE
Rao Kaixin

Assignees

厦门大学

Dates

Publication Date: 20260508
Application Date: 20251223

Claims (9)

1. The power distribution transmission method under the OCDM frequency selection channel is characterized by comprising the following steps: acquiring an original symbol sequence carrying transmission information; converting the original symbol sequence carrying the transmission information into a frequency domain by adopting a discrete Fourier transform matrix, carrying out dynamic power precoding on the frequency domain by adopting a power distribution matrix, converting a frequency domain signal subjected to power distribution into a time domain by adopting an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and adding a cyclic prefix to obtain a transmitting signal; Transmitting the transmitting signal through a frequency selective channel according to the correspondingly allocated power; receiving the transmitting signal, removing the cyclic prefix, converting the cyclic prefix into a frequency domain by adopting a discrete Fourier transform matrix, and obtaining a channel frequency response matrix according to a channel time domain response matrix; And designing a frequency domain equalizer by adopting a minimum mean square error criterion according to the channel frequency response matrix and the power distribution matrix so as to synchronously eliminate channel distortion and a transmitting end power weighting effect, and converting the equalized frequency domain signal into a time domain by adopting an inverse discrete Fourier transform matrix so as to demodulate and restore an original symbol sequence.
2. The method for power allocation transmission in an OCDM frequency selective channel as recited in claim 1, wherein the power allocated frequency domain signal is converted to a time domain according to the following formula: Wherein, the To convert the power-allocated frequency domain signal into a time domain CP-OCDM signal, Representing an inverse discrete fresnel transform matrix of size N, Representing an inverse discrete fourier transform matrix of size N, Representing a power distribution matrix which is an N diagonal matrix, diagonal elements The power allocation coefficient for each subcarrier is calculated from the channel state information and the minimum mean square error criterion, Representing the constellation-mapped original symbol sequence.
3. The method for power allocation and transmission in an OCDM frequency selective channel as recited in claim 2, wherein the discrete fresnel transformation matrix is obtained according to the following formula: Wherein, the Representing a discrete fresnel transformation matrix of size N, m representing the m-th row of elements of the discrete fresnel transformation matrix, The nth column element of the matrix is represented, and j represents an imaginary unit.
4. The method for power allocation transmission in an OCDM frequency selective channel as recited in claim 3, wherein the channel frequency response matrix is obtained according to the following formula: Wherein, the Representing the channel frequency response matrix, Representing a normalized orthogonal discrete fourier transform matrix of size N, Representing a channel time domain response matrix, a time domain channel convolution matrix obtained by constructing a Toeplitz matrix.
5. The method for power allocation transmission in an OCDM frequency selective channel as recited in claim 4, wherein the equalized frequency domain signal is obtained according to the following formula: Wherein, the Representing the frequency domain signal after equalization, Representing a diagonal matrix, the kth diagonal element of which For the coefficients of a single tap equalizer, Representing a diagonal matrix of diagonal elements Is a discrete Fresnel transformation matrix Characteristic values of (a), i.e., zadoff-Chu sequences, Representing the additive noise vector at the receiving end, Conforms to zero-mean Gaussian distribution and is a power Is a white noise of the (a) and (b), Representing the identity matrix.
6. The method for power allocation transmission in an OCDM frequency selective channel as recited in claim 5, wherein the diagonal elements of the diagonal matrix are obtained according to the following formula: Wherein, the Representing the diagonal elements of the kth subcarrier.
7. A computer readable storage medium, having stored thereon a power allocation transmission procedure under an OCDM frequency selective channel, which when executed by a processor, implements a power allocation transmission method under an OCDM frequency selective channel as claimed in any one of claims 1-6.
8. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor, when executing the computer program, implements the power allocation transmission method under an OCDM frequency selective channel as claimed in any one of claims 1-6.
9. A power allocation and transmission device under an OCDM frequency selective channel, comprising: The acquisition module is used for acquiring an original symbol sequence carrying transmission information; The coding module is used for converting the original symbol sequence carrying the transmission information into a frequency domain by adopting a discrete Fourier transform matrix, carrying out dynamic power precoding on the frequency domain by adopting a power distribution matrix, converting a frequency domain signal subjected to power distribution into a time domain by adopting an inverse discrete Fourier transform matrix and an inverse discrete Fresnel transform matrix, and adding a cyclic prefix to obtain a transmitting signal; the transmission module is used for transmitting the transmitting signal through a frequency selective channel according to the correspondingly allocated power; the conversion module is used for receiving the transmitting signals, converting the transmitting signals into a frequency domain by adopting a discrete Fourier transform matrix after removing cyclic prefixes, and obtaining a channel frequency response matrix according to a channel time domain response matrix; And the equalization decoding module is used for designing a frequency domain equalizer by adopting a minimum mean square error criterion according to the channel frequency response matrix and the power distribution matrix so as to synchronously eliminate channel distortion and a transmitting end power weighting effect, and converting an equalized frequency domain signal into a time domain by adopting an inverse discrete Fourier transform matrix so as to demodulate and restore an original symbol sequence.

Description

Power distribution transmission method and device under OCDM frequency selective channel Technical Field The present invention relates to the field of wireless communications technologies, and in particular, to a power allocation and transmission method under an OCDM frequency selective channel, a power allocation and transmission device under an OCDM frequency selective channel, a computer readable storage medium, and a computer device. Background In Linear Time Invariant (LTI) multipath channels, conventional orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM) techniques may employ water injection to achieve sub-channel power allocation to maximize frequency selective channel capacity, but still suffer from substantial limitations of being highly sensitive to carrier frequency offset and of not effectively utilizing channel diversity gain. The orthogonal frequency-modulated multiplexing (Orthogonal Chirp Division Multiplexing, OCDM) has better anti-interference performance, and particularly has obvious robustness to interference caused by insufficient guard interval. In order to fully exploit its anti-interference capability, an efficient transmit power allocation strategy is crucial. Most current schemes mainly surround the equalizer design itself, failing to adequately account for the inherent association and joint optimization between channel characteristics and receiver equalizer (e.g., minimum mean square error (Minimum Mean Square Error, MMSE) criteria). The OCDM technology replaces the Fourier transform core in the traditional OFDM by the chirp transform core, so that the OCDM technology inherently has stronger Doppler (carrier frequency offset) tolerance, can convert the energy dispersion of the channel response in a time-frequency domain into full diversity gain, and has remarkable theoretical performance advantages. However, when OCDM is applied to an actual frequency selective channel, its unique signal structure also presents new challenges, and the prior art has the following main drawbacks: (1) Channel energy dispersion causes the conventional power allocation algorithm to fail in that, unlike conventional OFDM subcarriers that experience approximately flat fading, the OCDM signal is in the fractional fourier domain, with the energy of a single symbol being dispersed over all components of the entire domain. This inherent "channel dispersion" effect breaks down the independence between subcarriers, making subcarrier power allocation schemes based on the "water-filling principle" in OFDM systems not directly applicable to OCDM systems. The existing method lacks a power distribution theory capable of effectively aiming at the channel energy dispersion characteristic, so that the power resource allocation of a transmitting end is not matched, and the available power resource cannot be utilized to the maximum extent. (2) Diversity gain is not fully exploited by joint optimization-although the dispersion characteristics of OCDM can be translated into full diversity gain, existing receiver designs (e.g., MMSE equalization) are often designed separately from transmit side power allocation. The design mode of the splitting cannot establish a cooperative optimization relation between the transmitting power and the receiving equalization, and the distribution of signals in a dispersion channel cannot be actively and adaptively molded through joint design, so that the degree of converting theoretical diversity gain into actual error rate performance improvement by the system is limited. (3) The system design fails to fully develop the inherent advantages of OCDM, namely the prior research is often focused on the frequency offset resistance of the OCDM when the OCDM is applied to a frequency selective channel, or only the equalization algorithm improvement is carried out from a receiving end, and the key degree of freedom of power distribution of a transmitting end is ignored. A unified transmitting power-receiving balance joint optimization framework cannot be constructed so as to systematically and simultaneously exert the frequency offset resistance advantage of OCDM and mine the full diversity potential of the OCDM under the frequency selective channel, so that the overall spectrum efficiency and the robustness of the system are not optimal. Disclosure of Invention The present invention aims to solve at least to some extent one of the technical problems in the above-described technology. Therefore, an object of the present invention is to provide a power distribution transmission method under an OCDM frequency selective channel, by which the transmission performance of the OCDM system under a frequency selective fading channel is improved through the joint design of power distribution and an equalizer. A second object of the present invention is to propose a computer readable storage medium. A third object of the invention is to propose a computer device. A