OFDM Communication Spectrum Resource Management Method Based on Reconfigurable Refractive Metasurfaces

Abstract

This invention discloses a spectrum resource management method for OFDM communication based on a reconfigurable refractive metasurface, comprising: acquiring communication system parameters; designing channel allocation based on the communication system parameters to maximize system capacity and data rate; and allocating sub-channels to individual users based on the channel allocation. This invention maximizes system capacity in OFDM communication systems based on reconfigurable refractive metasurface antennas by optimizing the spectrum resource allocation of channels.

Description

Technical Field

[0001] This invention relates to the field of electronics, specifically to a method for managing OFDM communication spectrum resources based on a reconfigurable refractive metasurface. Background Technology

[0002] Massive MIMO is a crucial component of future wireless communication. Existing massive MIMO systems utilize traditional phased array antennas for beamforming. However, traditional phased arrays suffer from high power consumption and high cost. To address this issue, reconfigurable reflective metasurface antennas have recently been proposed. However, these antennas suffer from the following drawback: the feed source can obstruct the reflected wave, resulting in low radiation efficiency. To address this, reconfigurable refractive metasurface antennas have been proposed. Since reconfigurable refractive metasurfaces do not suffer from feed obstruction, their radiation efficiency is higher than that of traditional reconfigurable reflective metasurface antennas. However, current research on reconfigurable refractive metasurface antennas primarily focuses on designing the antenna to optimize antenna-related parameters such as bandwidth and loss, without considering communication systems based on RRS (reconfigurable refractive metasurface) antennas. Summary of the Invention

[0003] To address the aforementioned issues, this invention discloses an OFDM communication spectrum resource management method based on a reconfigurable refractive metasurface, which optimizes the allocation of spectrum resource channels in an RRS antenna-based communication system, thereby maximizing system capacity.

[0004] The technical solution of the present invention includes:

[0005] A method for managing OFDM communication spectrum resources based on a reconfigurable refractive metasurface is applicable to an OFDM communication system consisting of a base station equipped with a reconfigurable refractive metasurface antenna and L users. The reconfigurable refractive metasurface antenna comprises a feed and a reconfigurable refractive metasurface. The steps include:

[0006] Obtain communication system parameters, including: the number of subcarriers, the frequency response of the channel from the feed to user l, the cyclic prefix length, the transmit power of the base station on each subcarrier, the noise variance in the received signal of user l, and the response of the reconfigurable refractive metasurface to different subcarriers;

[0007] Based on the communication system parameters, design channel allocation a. l,k To maximize system performance and speed;

[0008] Based on the channel allocation a l,k The sub-channels are then allocated to each user.

[0009] Furthermore, the channel frequency response from the feed to user l is obtained through the following steps:

[0010] 1) Based on the response of the (m,n)th element in the reconfigurable refractive metasurface, the frequency response of the channel from the feed source to the (m,n)th element, and the frequency response of the channel from the (m,n)th element to user l, calculate the frequency response of the (m,n)th metasurface-based channel.

[0011] 2) Based on the frequency response of the (m,n)th metasurface-based channel and the number of elements, the channel frequency response from the feed to user l is obtained.

[0012] Furthermore, the response of the (m,n)th cell includes the refraction amplitude and phase shift of the cell for different subcarriers, wherein the phase shift can vary in the range [0,2π) as the cell state changes.

[0013] Furthermore, the system and rate C = ∑ l C l C l The average rate at which the base station sends data to user l.

[0014] Furthermore, the average rate at which the base station sends data to user l Where K is the number of subcarriers, K C P is the length of the cyclic prefix. k Let σ be the base station's transmit power on subcarrier k. 2 Let g be the noise variance in the signal received by user l. l,k This is the frequency response of the channel from the feed source to user l.

[0015] Furthermore, channel allocation a is designed through the following steps. l,k :

[0016] 1) Construct an optimization problem, where the variables to be optimized include the channel allocation scheme, and the objectives to be optimized include the system and the rate;

[0017] 2) Based on the constraints, the optimization problem is solved using mathematical methods to obtain the channel allocation a. l,k .

[0018] Furthermore, the constraint condition includes: a sub-channel can be allocated to at most one user.

[0019] A storage medium storing a computer program, wherein the computer program is configured to execute the method described above at runtime.

[0020] An electronic device includes a memory and a processor, wherein the memory stores a program for performing the methods described above.

[0021] Compared with existing technologies, this invention can maximize system capacity in communication systems based on reconfigurable refractive metasurface antennas by optimizing the allocation of spectrum resources in the channel. Attached Figure Description

[0022] Figure 1 A schematic diagram of a reconfigurable refractive metasurface.

[0023] Figure 2 The system model of this invention.

[0024] Figure 3 A comparison of the frequency responses of reconfigurable refractive metasurfaces and reconfigurable reflective metasurfaces.

[0025] Figure 4 The method flowchart of the present invention.

[0026] Figure 5 A comparison chart of experimental data between the present invention and existing technologies. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only specific embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] 1. Reconfigurable refractive metasurface antenna

[0029] A reconfigurable refractive metasurface antenna consists of a feed and a refractive metasurface. (See attached image.) Figure 1 As shown, a refractive metasurface is an array of multiple subwavelength units. Each unit has a PIN diode, which can be switched between ON and OFF by adjusting the bias voltage across it. When a signal is incident on each unit, it is refracted. By adjusting the state of the diode on the unit, the phase of the refracted wave can be changed.

[0030] The beamforming process of this reconfigurable refractive metasurface antenna is as follows: After the signal emitted by the feed is incident on each element, it undergoes refraction. During this refraction process, the metasurface element applies a certain phase shift to the signal. By adjusting the bias voltage on the diodes, the refraction phase shift of the element is appropriately set, thereby achieving beamforming.

[0031] 2. OFDM (Orthogonal Frequency Division Multiplexing) Communication Spectrum Resource Management Method Based on Reconfigurable Refractive Metasurfaces

[0032] The system model of the present invention is as follows: Figure 2 As shown, consider a broadband downlink network containing L users and one base station. Assume the users are equipped with omnidirectional antennas. For beamforming, the base station uses a reconfigurable refractive metasurface antenna. To reduce the adverse effects of channel frequency selectivity, the base station uses OFDM to communicate with each user. Assume the number of subcarriers in the system is K. To avoid inter-user interference, assume each subcarrier is assigned to at most one user. This invention introduces a... l,k This indicates the channel allocation, where a l,k =1 indicates that subchannel k has been assigned to user k, a l,k =0 indicates no allocation.

[0033] Assume the refractive metasurface contains M*N units, each unit having a size of s. M ×s N In the system of this invention, the difference in the response of the reconfigurable refractive metasurface unit to different subcarriers cannot be ignored. This is because: firstly, due to the use of OFDM, the bandwidth of the transmitted signal is relatively large; secondly, the reconfigurable refractive metasurface proposed in this invention is mainly aimed at replacing phased arrays in the millimeter-wave band, while in the millimeter-wave band, the beam splitting effect caused by the different responses of the unit to different subcarriers cannot be ignored. Here, this invention denotes the refractive amplitude and phase shift of the (m,n)th unit to the kth subcarrier as... and The refractive index of this unit can then be written as When the state of a cell changes, the phase shift of the cell can vary within the range of [0, 2π).

[0034] Suppose the channel from the base station feed to user l consists of M×N metasurface-based channels, where the (m,n)th channel represents the channel from the feed through the (m,n)th metasurface unit to user l. The frequency response of the (m,n)th metasurface-based channel can be expressed as:

[0035]

[0036] Among them, Γ m,n This represents the frequency response of the (m,n)th element, i.e. f m,n Let represent the frequency response of the channel from the feed to the (m,n)th unit of the RRS. Let represent the frequency response of the channel from the (m,n)th unit of the RRS to user l, and ⊙ represent the Hadamard product. f m,n ,as well as Both are vectors of length K. Therefore, the frequency response of the channel from the feed source to user l can be expressed as:

[0037]

[0038] Assuming subcarrier k is assigned to user l, the received signal of that user on that subcarrier can be expressed as:

[0039]

[0040] Among them, g l,k Represents the frequency response vector g l The k-th component, x k n represents the symbol transmitted by the base station on sub-channel k. l,k This represents the zero-mean additive white Gaussian noise contained in the received signal, and the variance of this noise is denoted as σ in this invention. 2 Therefore, within one OFDM symbol, the average rate at which the base station sends data to user l is:

[0041]

[0042] Among them, K C P represents the length of the cyclic prefix. k This represents the base station's transmit power on subcarrier k. Therefore, the system's sum rate can be expressed as...

[0043]

[0044] Next, we introduce a spectrum resource management method for OFDM communication based on reconfigurable refractive metasurfaces. Note that the different responses of elements to different subcarriers present a challenge to the design of the spectrum resource management method. Specifically, because the elements respond differently to different subcarriers, the direction of the transmitted beam corresponding to each subcarrier also differs, resulting in different channels for each subcarrier. Therefore, when allocating spectrum resources, it is necessary to consider not only how many subcarriers to allocate to each user, but also which subcarriers to allocate. Furthermore, existing spectrum resource allocation methods applicable to OFDM systems based on reconfigurable reflective metasurfaces cannot be directly used because the response distribution of reconfigurable reflective metasurface elements under different subcarriers differs from that of reconfigurable transmissive metasurfaces. Figure 3 As shown.

[0045] To overcome the above challenges, this invention proposes the following spectrum resource management method. For example... Figure 4 As shown, this invention models the spectrum resource management problem as an optimization problem, and optimizes the allocation of spectrum resources a. l,k This maximizes the system and speed C. The optimization problem can be written in the following form:

[0046]

[0047]

[0048] The above optimization problem can be solved mathematically, and the result can be used as the final spectrum resource allocation scheme.

[0049] The simulation environment for this invention and a prior art is as follows: the base station transmit power is set to 43dBm, the variance of additive white Gaussian noise is set to -96dBm, the system operating frequency is set to 26GHz, assuming the number of users is 2, the distance between the two users and the metasurface array (or phased array) is 200m, and an omnidirectional antenna is used to receive the signal. For the reconfigurable refractive metasurface antenna, it is equipped with a feed, and the radiation pattern of the feed is denoted as G(θ,φ), whose values ​​are: when At that time, G(θ,φ)=6cos 2 θ; otherwise, G(θ,φ)=0. The spacing of the metasurface array is 0.15m. Assume the unit cell transmittance is 0.8 and the unit cell size is... Where λ is the wavelength corresponding to the system's operating frequency. For comparison, this invention considers the system performance when using a single small phased array as the base station antenna. For the phased array antenna, the spacing between elements is set to half a wavelength, and it is assumed that the elements are omnidirectional antennas. In OFDM, the length of the cyclic prefix is ​​16, and the number of subcarriers is 64. For example... Figure 5 As shown, compared to traditional phased arrays, reconfigurable refractive metasurface antennas can deliver higher sum rates.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for managing OFDM communication spectrum resources based on reconfigurable refractive metasurfaces, applicable to base stations equipped with reconfigurable refractive metasurface antennas and A communication system using OFDM, comprising multiple users, wherein the reconfigurable refractive metasurface antenna consists of a feed and a reconfigurable refractive metasurface, and the steps include: Obtain communication system parameters, including: number of subcarriers, feed rate to user. The channel's frequency response, cyclic prefix length, base station transmit power on each subcarrier, and user... Noise variance in the received signal, and the response of the reconfigurable refractive metasurface to different subcarriers; Design channel allocation based on the communication system parameters. To maximize system performance and speed; Based on the channel allocation The sub-channels are then allocated to each user. The feed source to the user is obtained through the following steps. The frequency response of the channel: Based on the first reconfigurable refractive metasurface The frequency response of the unit, the feed to the first The frequency response of the channel of the first unit is the same as that of the second unit. Unit to user The frequency response of the channel is calculated. The frequency response of a metasurface-based channel; where the first... Frequency response of each unit The frequency response of the (m,n)th unit to the kth subcarrier Let be the refraction coefficient of the (m,n)th cell for the kth subcarrier, and , This represents the refraction amplitude of the (m,n)th element with respect to the kth subcarrier. This represents the phase shift of the (m,n)th unit with respect to the kth subcarrier, the phase shift... exist The range changes with the state of the (m,n)th unit. ; According to the The frequency response of a metasurface-based channel and the number of elements are used to obtain the feed to the user. The frequency response of the channel; Among them, in users In subcarrier Received signal on In the case of the system and rate Among them, the base station provides users with Average rate of data transmission , For the number of subcarriers, The length of the cyclic prefix. For base stations on subcarriers On the transmit power, For users Noise variance in the received signal For feed to users The frequency response of the channel, This represents the received signal The zero-mean additive white Gaussian noise it contains The symbol representing the base station transmitting on sub-channel k; The channel allocation is designed through the following steps. : Construct an optimization problem: and ; Based on the constraints, the optimization problem is solved mathematically to obtain the channel allocation. The constraints include: a sub-channel can be assigned to at most one user.

2. A storage medium storing a computer program, wherein, The computer program is configured to execute the method of claim 1 at runtime.

3. An electronic device comprising a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the method of claim 1.

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