Sub-6 wireless network communication enhancement method based on dual-frequency programmable metasurface

Abstract

This application relates to a method for enhancing Sub-6 wireless network communication based on a dual-frequency programmable metasurface. The dual-frequency programmable metasurface structure is compact, low-cost, and simple in structure, and supports beamforming on two Sub-6 ISM bands simultaneously, enabling IoT devices with different frequencies and protocols to have beamforming capabilities. The method of this application can simultaneously achieve beamforming on two Sub-6 ISM bands to improve the wireless communication performance of commercial IoT devices.

Description

Technical Field

[0001] This application relates to the field of Internet of Things (IoT) communication, and more specifically, to a method for enhancing Sub-6 wireless network communication based on a dual-frequency programmable metasurface. Background Technology

[0002] Most IoT devices, constrained by factors such as size, power consumption, and price, typically have fewer than three antennas. Due to environmental multipath effects, the beam patterns of these inexpensive, limited-number antennas cannot guarantee uniform and stable signal propagation in complex indoor environments, resulting in low communication performance. Therefore, beamforming technology is often used in wireless communication systems to improve link throughput and extend communication range.

[0003] Many studies have focused on using antenna arrays in radio frequency (RF) terminals to achieve high beamforming gain. However, in practical applications, the real-world deployment of radio systems with large antenna arrays faces two major challenges: First, due to cost and form factor constraints, most IoT devices today must be very small, leaving insufficient space to accommodate bulky antenna arrays; second, these systems require tight integration of antennas, RF front-ends, and baseband hardware, leading to increased power consumption and high hardware costs.

[0004] Recently, the transfer of beamforming functionality from the communication endpoint to smart surfaces deployed in propagation environments has attracted considerable attention from researchers, such as LAIA, RFocus, and RFlens. While these smart surfaces can achieve beamforming, they also face practical limitations. First, they have large areas. For example, RFocus uses 3200 antenna elements, achieving a median gain of 9dB for the wireless link within an area of ​​6 square meters. Such a large metasurface is difficult to deploy flexibly in complex environments. Moreover, RFocus only utilizes a portion of its elements at a time, redirecting only a small portion of the signal energy, leaving significant room for improvement in its area utilization efficiency. Second, they are limited to specific operating frequency bands. Current metasurface-based beamforming solutions focus on optimizing communication performance in a single frequency band; for example, RFocus is suitable for frequencies below 3GHz, while RFlens is optimized for the 5GHz band. However, IoT devices (cameras, smart bulbs, etc.) often operate on different frequency bands (2.4GHz and 5GHz) and different protocols (such as Wi-Fi, Bluetooth, ZigBee). It is very common for densely deployed IoT devices to conduct concurrent wireless transmission through two Sub-6 ISM bands (2.4GHz and 5GHz). Therefore, single-band metasurfaces cannot meet the needs of practical applications.

[0005] To support dual-band operation of IoT devices, a straightforward solution is to deploy two single-band metasurfaces operating at different frequencies. However, this not only requires more deployment space to accommodate the additional metasurfaces but also incurs higher costs. Another solution is to stack one metasurface on top of another, but such methods lead to complex control circuit designs. Recent work has used varactor diodes to adjust the phase for dual-band operation, which introduces high insertion losses and requires a precise and complex DC voltage control backend.

[0006] In summary, existing beamforming technologies have shortcomings in terms of efficiency and versatility. Therefore, a more feasible beamforming technology is needed. Summary of the Invention

[0007] To overcome at least one deficiency in the prior art, this application provides a Sub-6 wireless network communication enhancement method based on a dual-frequency programmable metasurface.

[0008] In a first aspect, a method for enhancing communication in a Sub-6 wireless network based on a dual-frequency programmable metasurface is provided, comprising:

[0009] A dual-frequency programmable metasurface structure is constructed, which includes multiple metasurface units. Each metasurface unit can generate two resonant frequencies and four phase values.

[0010] Determine the optimal coding mode for dual-frequency programmable metasurface structures to achieve dual-band beamforming under different incident and exit angles;

[0011] Determine at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode;

[0012] Based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, determine the coding mode that can provide the best communication signal quality, as the final coding mode under different incident and exit angles.

[0013] The relative direction of the target is detected. The relative direction is either the incident angle of the uplink or the exit angle of the downlink. The final encoding mode corresponding to the relative direction of the target is selected as the encoding mode used for communication.

[0014] In one embodiment, the metasurface unit includes a top metal square patch, a middle dielectric cube, and a bottom metal layer. The width w of the metal square patch is 19.5 mm, the length l of the metal square patch is 19.5 mm, and the height h of the dielectric cube is 6.8 mm.

[0015] A groove is etched at the top left, bottom left, top right, and bottom right edges of the metal square patch, and the width of each groove is w. s It is 7mm long and the groove length is l. s It is 0.5mm.

[0016] In one embodiment, a rectangular groove is etched between two grooves in the same column along the column direction, and a PIN diode is embedded in each rectangular groove; the two PIN diodes are in an "on" or "off" state at different DC voltage levels, and the combination obtains four states of the metasurface unit to generate four corresponding phase values.

[0017] In one embodiment, determining the optimal coding mode for dual-frequency programmable metasurface structures to achieve dual-band beamforming under different incident and exit angles includes:

[0018] Construct the objective function:

[0019]

[0020] Where, η * For optimal encoding mode, To determine the theoretical maximum signal strength achievable in the 2.4 GHz band using the optimal phase offset, The theoretical maximum signal strength achieved in the 5GHz band using the optimal phase offset; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure;

[0021] The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0022]

[0023] in, The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure, η 2.4G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. For encoding mode η 2.4G The phase state of the (m,n)th metasurface unit;

[0024] Intensity of 5GHz signal reflected by dual-frequency programmable metasurface structure:

[0025]

[0026] in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. For encoding mode η 5G The phase state of the (m,n)th metasurface unit;

[0027] Solving the objective function yields the optimal coding mode for dual-frequency beamforming using a dual-frequency programmable metasurface structure.

[0028] In one embodiment, solving the objective function includes:

[0029] A genetic algorithm is used to solve the objective function. During the solution process, the coding mode η of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength implemented in the 2.4 GHz band is used. 2.4G The coding mode η of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength achieved in the 5GHz band. 5G As the initial chromosome in the initial population of the genetic algorithm.

[0030] In one embodiment, determining at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode includes:

[0031] The metasurface unit TU that has little or no impact on the main lobe in the 2.4 GHz band was identified. 2.4G :

[0032]

[0033] Among them, PM 2.4G Let φ(·) represent the phase of the main lobe in the 2.4 GHz band. The angle of incidence required to generate a 2.4 GHz signal. f is the emission angle of the 2.4 GHz signal reflected by the metasurface unit. 2.4G This indicates a frequency of 2.4GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0034] Phase PM of the main lobe in the 2.4 GHz band 2.4G :

[0035]

[0036] Where ∠ represents the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure;

[0037] Identify metasurface unit sets TU that have little or no impact on the main lobe in the 5GHz band. 5G :

[0038]

[0039] Among them, PM 5G The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, f is the emission angle of the 5 GHz signal reflected by the metasurface unit. 5G This indicates a frequency of 5GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0040] Phase PM of the main lobe in the 5GHz band 5G :

[0041]

[0042] Find the metasurface unit set TU in the 2.4 GHz band. 2.4G and the metasurface unit TU in the 5GHz band 5G The intersection TU serves as at least one metasurface unit in the dual-frequency programmable metasurface structure that has little or no negative impact on the main lobe.

[0043] In one embodiment, based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, a coding mode that can provide the best communication signal quality is determined as the final coding mode for different incident and exit angles, including:

[0044] For each set of incident and exit angles corresponding to the optimal coding mode, the phase state of at least one metasurface unit in the optimal coding mode that has little or no impact on the main lobe is changed to obtain multiple updated coding modes.

[0045] The coding scheme that provides the best communication signal quality among several updated coding schemes is determined as the final coding scheme.

[0046] Secondly, a Sub-6 wireless network communication enhancement device based on a dual-frequency programmable metasurface is provided, comprising:

[0047] The dual-frequency programmable metasurface structure comprises multiple metasurface units, each capable of generating resonant frequencies in two frequency bands and four phase values.

[0048] The optimal coding mode determination module is used to determine the optimal coding mode for dual-frequency programmable metasurface structures to achieve dual-band beamforming under different incident and exit angles.

[0049] A negative impact metasurface unit determination module is used to determine at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode;

[0050] The final coding mode determination module is used to determine the coding mode that can provide the best communication signal quality based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, as the final coding mode under different incident and exit angles.

[0051] The communication coding mode determination module is used to detect the incident angle or exit angle of the target, select the final coding mode corresponding to the incident angle or exit angle of the target, and use it as the coding mode for communication.

[0052] In one embodiment, the optimal encoding mode determination module is also used for:

[0053] Construct the objective function:

[0054]

[0055] Where, η * For optimal encoding mode, To determine the theoretical maximum signal strength achievable in the 2.4 GHz band using the optimal phase offset, The theoretical maximum signal strength achieved in the 5GHz band using the optimal phase offset; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure;

[0056] The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0057]

[0058] in, The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure, η 2.4G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. For encoding mode η 2.4G The phase state of the (m,n)th metasurface unit;

[0059] Calculate the intensity of the 5 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0060]

[0061] in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, η 5G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. For encoding mode η 5G The phase state of the (m,n)th metasurface unit;

[0062] Solving the objective function yields the optimal coding mode for dual-frequency beamforming using a dual-frequency programmable metasurface structure.

[0063] In one embodiment, the negative impact metasurface unit determination module is further configured to:

[0064] The metasurface unit TU that has little or no impact on the main lobe in the 2.4 GHz band was identified. 2.4G :

[0065]

[0066] Among them, PM 2.4G Let φ(·) represent the phase of the main lobe in the 2.4 GHz band. The angle of incidence required to generate a 2.4 GHz signal. f is the emission angle of the 2.4 GHz signal reflected by the metasurface unit. 2.4G This indicates a frequency of 2.4GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0067] Phase PM of the main lobe in the 2.4 GHz band 2.4G :

[0068]

[0069] Where ∠ represents the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure;

[0070] Identify metasurface unit sets TU that have little or no impact on the main lobe in the 5GHz band. 5G :

[0071]

[0072] Among them, PM 5G The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, f is the emission angle of the 5 GHz signal reflected by the metasurface unit. 5G This indicates a frequency of 5GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0073] Phase PM of the main lobe in the 5GHz band 5G :

[0074]

[0075] Find the metasurface unit set TU in the 2.4 GHz band. 2.G and the metasurface unit TU in the 5GHz band 5G The intersection TU, as at least one metasurface unit, has little or no negative impact on the main lobe under the optimal coding mode. Compared with the prior art, this application has the following beneficial effects: The Sub-6 wireless network communication enhancement method based on dual-frequency programmable metasurfaces in this application is based on a dual-frequency programmable metasurface with a compact area, low cost, and simple structure. It supports beamforming on two Sub-6 ISM bands simultaneously, enabling IoT devices with different frequencies and protocols to have beamforming capabilities. Experiments have shown that even a relatively small 16*16 unit array can achieve an average signal strength improvement of 12.08dB and a throughput improvement of 2.49 times. The method of this application can simultaneously achieve beamforming on two Sub-6 ISM bands to improve the wireless communication performance of commercial IoT devices. Attached Figure Description

[0076] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings:

[0077] Figure 1 This application illustrates a method for enhancing Sub-6 wireless network communication based on a dual-frequency programmable metasurface, according to an embodiment of the present application.

[0078] Figure 2 A schematic diagram of the metasurface unit is shown, wherein (a) is a three-dimensional view of the metasurface unit, (b) is a structural diagram of the metal square patch, (c) is a structural diagram of the dielectric cube, and (d) is a structural diagram of the metal layer;

[0079] Figure 3 A structural block diagram of a Sub-6 wireless network communication enhancement device based on a dual-frequency programmable metasurface according to an embodiment of this application is shown;

[0080] Figure 4 A conceptual diagram illustrating the operation of a dual-frequency programmable metasurface structure is shown.

[0081] Figure 5 A schematic diagram of the reflection phase and reflection coefficient of the metasurface unit is shown;

[0082] Figure 6 The signal strength diagrams at different scanning angles for different frequency bands are shown, where (a) is the signal strength diagram at different scanning angles for the 2.4 GHz band, and (b) is the signal strength diagram at different scanning angles for the 5 GHz band.

[0083] Figure 7 The results of signal gain improvement of dual-band concurrent beamforming under different target directions are shown in the figure, where (a) is a schematic diagram of scene layout and (b) is a figure of SNR improvement experiment results;

[0084] Figure 8 The diagrams show the throughput improvement effects of IoT devices with different frequencies and protocols. (a) is the deployment layout diagram, and (b) is the throughput result diagram. Detailed Implementation

[0085] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.

[0086] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution according to this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0087] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0088] This application provides a Sub-6 wireless network communication enhancement method based on a dual-frequency programmable metasurface, which can simultaneously achieve beamforming on two Sub-6 ISM bands to improve the wireless communication performance of commercial IoT devices. The dual-frequency programmable metasurface is compact, low-cost, and simple in structure, and supports beamforming on two Sub-6 ISM bands simultaneously, enabling IoT devices with different frequencies and protocols to have beamforming capabilities.

[0089] Figure 1 A method for enhancing Sub-6 wireless network communication based on a dual-frequency programmable metasurface, according to an embodiment of this application, is illustrated. See [link to relevant documentation]. Figure 1 The methods include:

[0090] Step S1: Construct a dual-frequency programmable metasurface structure. The dual-frequency programmable metasurface structure includes multiple metasurface units, each of which can generate resonant frequencies in two frequency bands and four phase values. Here, the two frequency bands can be 2.4 GHz and 5 GHz.

[0091] Step S2: Determine the optimal coding mode for dual-frequency programmable metasurface structure to achieve dual-frequency beamforming under different incident and exit angles.

[0092] This step takes into account two factors: first, the optimal phase shift varies significantly across different frequencies and target directions; second, due to hardware design, the phase shift introduced by the metasurface at different center frequencies differs under the same diode state (i.e., encoding), meaning the metasurface structure cannot simultaneously achieve optimal phase shifts in both frequency bands, nor can an analytical solution that strictly satisfies the beamforming phase requirements be found. Therefore, the optimal encoding mode for the metasurface unit state is directly sought to maximize the total gain of the main lobe in both frequency bands during metasurface beamforming.

[0093] Step S3: Determine at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode.

[0094] Step S4: Based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, determine the coding mode that can provide the best communication signal quality, as the final coding mode under different incident and exit angles.

[0095] Research has revealed that in dual-band programmable metasurface structures, some metasurface units contribute negligibly to the main lobe or may even have a negative impact. However, these same metasurface units significantly affect the distribution of side lobes, especially when the metasurface is configured in dual-band mode. Although side lobe signals are not directly transmitted to the receiver, they may still reach the receiver after being reflected by various objects in the propagation environment. Therefore, by identifying at least one metasurface unit with minimal or no negative impact on the main lobe under the optimal coding mode, the coding of this metasurface unit can be modified to adjust the side lobes while minimizing the impact on the main lobe in both frequency bands, thereby further improving signal strength.

[0096] Step S5: Detect the relative direction of the target. The relative direction is the incident angle of the uplink or the exit angle of the downlink. Select the final encoding mode corresponding to the relative direction of the target as the encoding mode used for communication.

[0097] Here, the relative direction of the target can be detected using a beam alignment scheme. The relative direction refers to the uplink incident angle or the downlink exit angle. To accurately orient the reflected signal from the metasurface structure towards the receiver, the wireless signal incident angle θ needs to be known. i and the angle of departure θ d Observations reveal that in typical Wi-Fi systems, access points (APs) are static in most cases. Therefore, the downlink signal incident angle and the uplink emission angle are both fixed and known. Thus, the search involves identifying the unknown angles: the uplink incident angle and the downlink emission angle.

[0098] Taking the following downlink communication as an example, it is necessary to search for the outgoing angle θ. d This refers to the relative direction of the detected target. In the nth round of beam search, the metasurface structure configures its cells and points its main lobe at a specific angle. In this configuration, upon receiving a data packet, the receiver embeds 1 bit in its ACK (Acknowledge character) to indicate whether the received signal quality of the metasurface structure has improved compared to the previous configuration; 1 indicates improvement, and 0 indicates deterioration. A Wi-Fi receiver is equipped on the metasurface structure to listen for ACKs. After iterating through all possible emission angles, θ is selected to provide the highest received signal quality. dThe relative direction of the detected target is the downlink emission angle corresponding to the target. A two-stage search algorithm can be used. In the first stage, a relatively large step size of 20° is used for searching. In the second stage, after obtaining a coarse direction, a smaller step size of 5° is used to fine-tune the result, ultimately obtaining θ. d .

[0099] In this step, each set of incident angles and exit angles corresponds to a final encoding mode. After the relative direction of the target is determined, the final encoding mode corresponding to the relative direction of the target is used as the encoding mode for communication, thereby enhancing the communication capability of the Sub-6 wireless channel.

[0100] In one embodiment, Figure 2 A schematic diagram of a metasurface unit is shown, wherein (a) is a three-dimensional view of the metasurface unit, (b) is a structural diagram of a metal square patch, (c) is a structural diagram of a dielectric cube, and (d) is a structural diagram of a metal layer; see also Figure 2 Metasurface units are constructed on a square structure with metal patches. Each metasurface unit comprises a top metal square patch, a middle dielectric cube, and a bottom metal layer, all three parts tightly connected. According to cavity model theory, the resonant frequency of this patch structure is determined by the patch length *l*, the patch width *w*, and the height *h* of the dielectric cube.

[0101] To achieve area efficiency in metasurfaces, allowing more metasurface cells to be embedded within a given area, the width *w* and length *l* of the metasurface cells need to be as small as possible. However, for a fixed dielectric cube height *h*, reducing *w* and *l* leads to an increase in the resonant frequency. Therefore, to maintain the metasurface resonant frequency at 2.4 GHz while achieving area efficiency, the thickness *h* of the dielectric cube of the metasurface cells needs to be large. To balance the size and thickness of the metasurface cells, the width *w* and length *l* of the metal square patch were set to 19.5 mm, and the height *h* of the dielectric cube was set to 6.8 mm, achieving a resonant frequency of 2.4 GHz.

[0102] To generate a resonant frequency in the second Sub-6 ISM band (5GHz) without affecting the first resonant frequency, the structure of the metasurface unit is optimized. The specific method is as follows:

[0103] Etching grooves on a surface mount device can generate additional resonant frequencies, the of which depend on the location, number, and size of the grooves.

[0104] To investigate the relationship between the slot location and the resonant frequency, six candidate slot locations were selected on the patch, and the resonant frequencies of the metasurface units were calculated using HFSS (High Frequency Simulator Structure) simulations. The results show that slots located at the patch edges have the least impact on the first resonant frequency while simultaneously generating a second resonant frequency. Slots in the center significantly alter the first resonant frequency (shifting it from 2.4 GHz to 2.1 GHz). This is because the current distribution on the metal patch is highly uneven: the current at the patch edges is significantly weaker than the current at the patch center. Narrow slots in areas with lower current on the patch only slightly perturb the original resonant frequency. Therefore, it was ultimately decided to etch slots at the patch edges to ensure that the first resonant frequency remains at 2.4 GHz while generating the second resonant frequency.

[0105] Although etching grooves can generate a second resonant frequency, the second resonant frequency generated by etching only a single groove results in a very weak signal reflection. To enhance the reflected signal, the solution is to etch grooves at multiple patch edge locations to form an antenna array. HFSS simulation results show that the reflected signal strength of the second resonant frequency does indeed increase with the number of grooves. Therefore, a groove is simultaneously etched at the upper left, lower left, upper right, and lower right edges of the square patch.

[0106] At this point, although the reflected signal intensity at the second resonant frequency increased, the frequency deviated from the desired 5 GHz. Therefore, further fine-tuning of the slot's physical dimensions was necessary to shift the second resonant frequency back to 5 GHz. HFSS was used to calculate different slot widths w. s and groove length l s The impedance of the lower metasurface unit was found to be w s and l s Increasing this value can lead to a decrease in the second resonant frequency. The final choice is w. s =7mm and l s With a slot size of 0.5mm, the optimized metasurface unit can not only achieve resonant frequencies of 5GHz and 2.4GHz, but also maximize the reflection efficiency of the metasurface unit in both operating frequency bands.

[0107] In one embodiment, considering the need for simple control, PIN diodes were chosen as adjustable electronic components embedded in the metal patch of the metasurface unit. Changing the state of the PIN diodes achieves the function of altering the phase of the metasurface unit (i.e., phase programmability). Specifically, a rectangular slot is etched along the column direction between two slots in the same column, and a PIN diode is embedded in each rectangular slot. The two PIN diodes are in an "on" or "off" state at different DC voltage levels, and combinations yield four states of the metasurface unit, generating four corresponding phase values. Ultimately, this achieves a phase difference of approximately 2 / π between the states of each metasurface unit in both the 2.4 GHz and 5 GHz frequency bands. Therefore, the metasurface unit can be considered as a 2-bit phase shifter.

[0108] In one embodiment, at a given angle of incidence and In this case, it is necessary to find the optimal encoding mode η * While ensuring along the exit angle and To maximize signal strength while avoiding over-optimization of a single frequency band and ensuring fairness between the two bands, this study first models the propagation process of the wireless signal through the metasurface, calculates the theoretical maximum signal strength for single-band beamforming at 2.4 GHz and 5 GHz respectively, and uses these as the signal strength thresholds for each band under dual-band simultaneous beamforming. Then, an objective function is designed and optimized based on these thresholds.

[0109] The wireless signal travels different propagation distances before reaching the metasurface element, resulting in an initial phase difference. Similarly, the outgoing path also causes a phase difference. To achieve beamforming in the outgoing angle direction, the wireless signals need to be constructively superimposed, meaning that all signals reflected by the metasurface element along the outgoing direction must have the same phase. Therefore, the optimal phase offset γ of the metasurface element can be calculated for different frequency bands, given the incident and outgoing directions. 2.4G and γ 5G , and That is, using the optimal phase offset γ respectively 2.4G and γ 5G The theoretical maximum signal strength achieved in the 2.4 GHz and 5 GHz bands corresponds to the metasurface unit coding mode η. 2.4G and η 5G Based on the above, an objective function is constructed and solved to obtain the optimal encoding pattern.

[0110] In this embodiment, step S2, which determines the optimal coding mode for dual-frequency programmable metasurface structures to achieve dual-band beamforming under different incident and exit angles, may include:

[0111] Step S21, construct the objective function:

[0112]

[0113] Where, η * For optimal encoding mode, To use the optimal phase offset γ 2.4G The theoretical maximum signal strength achieved in the 2.4 GHz band. To use the optimal phase offset γ 5G The theoretical maximum signal strength achieved in the 5GHz band; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure;

[0114] The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0115]

[0116] in, The angle of incidence required to generate a 2.4 GHz signal. This is the emission angle of the 2.4 GHz signal reflected by the metasurface unit; this value is equal for all metasurface units. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure, the dual-frequency programmable metasurface structure has M×N metasurface units, η 2.4G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. For encoding mode η 2.4G The phase state of the (m,n)th metasurface unit, where m∈(1,M) and n∈(1,N).

[0117] Intensity of 5GHz signal reflected by dual-frequency programmable metasurface structure:

[0118]

[0119] in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, η 5GThe coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. For encoding mode η 5G The phase state of the (m,n)th metasurface unit.

[0120] Step S22: Solve the objective function to obtain the optimal coding mode for dual-band beamforming using a dual-frequency programmable metasurface structure.

[0121] In this step, a genetic algorithm is used to solve the objective function. To accelerate the search, the coding mode η of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength implemented in the 2.4GHz band is used during the solution process. 2.4G The coding mode η of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength achieved in the 5GHz band. 5G As the initial chromosome in the initial population of the genetic algorithm, the optimal coding mode that can achieve dual-band beamforming is obtained through iterative optimization.

[0122] In one embodiment, step S3, determining at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode, may include:

[0123] Step S31: Determine the set of metasurface units TU that have little or no impact on the main lobe in the 2.4GHz frequency band. 2.4G :

[0124]

[0125] Among them, PM 2.4G Let φ(·) represent the phase of the main lobe in the 2.4 GHz band. The angle of incidence required to generate a 2.4 GHz signal. f is the emission angle of the 2.4 GHz signal reflected by the metasurface unit. 2.4G This indicates a frequency of 2.4GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0126] Phase PM of the main lobe in the 2.4 GHz band 2.4G :

[0127]

[0128] Where ∠ represents the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure;

[0129] Step S32: Identify the metasurface unit set TU that has little or no impact on the main lobe in the 5GHz band. 5G :

[0130]

[0131] Among them, PM 5G The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, f is the emission angle of the 5 GHz signal reflected by the metasurface unit. 5G This indicates a frequency of 5GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0132] Phase PM of the main lobe in the 5GHz band 5G :

[0133]

[0134] Step S33: Calculate the metasurface unit set TU in the 2.4GHz band. 2.4G and the metasurface unit TU in the 5GHz band 5G The intersection of TU, ​​TU = TU 2.4G ∩TU 5G As at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode.

[0135] Here, the intersection TU includes metasurface units that have negligible or even negative effects on both the 2.4 GHz and 5 GHz frequency bands.

[0136] In one embodiment, step S4, determining the coding mode that provides the best communication signal quality based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, as the final coding mode for different incident and exit angles, may include:

[0137] For each set of incident and exit angles corresponding to the optimal coding mode, the phase state of at least one metasurface unit in the optimal coding mode that has little or no impact on the main lobe is changed to obtain multiple updated coding modes.

[0138] The coding scheme that provides the best communication signal quality among several updated coding schemes is determined as the final coding scheme.

[0139] Employing the same inventive concept as the Sub-6 wireless network communication enhancement method based on a dual-frequency programmable metasurface, this embodiment also provides a corresponding Sub-6 wireless network communication enhancement device based on a dual-frequency programmable metasurface. Figure 3 A structural block diagram of a Sub-6 wireless network communication enhancement device based on a dual-frequency programmable metasurface according to an embodiment of this application is shown, including:

[0140] The dual-frequency programmable metasurface structure 31 includes multiple metasurface units, each of which can generate two frequency bands of resonant frequency and four phase values.

[0141] The optimal coding mode determination module 32 is used to determine the optimal coding mode for dual-frequency programmable metasurface structure to achieve dual-frequency beamforming under different incident and exit angles.

[0142] Negative impact metasurface unit determination module 33 is used to determine at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode.

[0143] The final coding mode determination module 34 is used to determine the coding mode that can provide the best communication signal quality based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, as the final coding mode under different incident and exit angles.

[0144] The communication encoding mode determination module 35 is used to detect the incident angle or exit angle corresponding to the target, select the final encoding mode corresponding to the incident angle or exit angle of the target, and use it as the encoding mode for communication.

[0145] In one embodiment, the optimal encoding mode determination module 32 is further configured to:

[0146] Construct the objective function:

[0147]

[0148] Where, η * For optimal encoding mode, To use the optimal phase offset γ 2.4G The theoretical maximum signal strength achieved in the 2.4 GHz band. To use the optimal phase offset γ 5G The theoretical maximum signal strength achieved in the 5GHz band; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure;

[0149] The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0150]

[0151] in, The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure, η 2.4G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. For encoding mode η 2.4G The phase state of the (m,n)th metasurface unit;

[0152] Calculate the intensity of the 5 GHz signal reflected by the dual-frequency programmable metasurface structure:

[0153]

[0154] in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, η 5G The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. For encoding mode η 5G The phase state of the (m,n)th metasurface unit;

[0155] Solving the objective function yields the optimal coding mode for dual-frequency beamforming using a dual-frequency programmable metasurface structure.

[0156] In one embodiment, the negative impact metasurface unit determination module 33 is further configured to:

[0157] The metasurface unit TU that has little or no impact on the main lobe in the 2.4 GHz band was identified. 2. :

[0158]

[0159] Among them, PM 2.4G Let φ(·) represent the phase of the main lobe in the 2.4 GHz band. The angle of incidence required to generate a 2.4 GHz signal. f is the emission angle of the 2.4 GHz signal reflected by the metasurface unit. 2.4GThis indicates a frequency of 2.4GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0160] Phase PM of the main lobe in the 2.4 GHz band 2.4G :

[0161]

[0162] Where ∠ represents the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure;

[0163] Identify metasurface unit sets TU that have little or no impact on the main lobe in the 5GHz band. 5G :

[0164]

[0165] Among them, PM 5G The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, f is the emission angle of the 5 GHz signal reflected by the metasurface unit. 5G This indicates a frequency of 5GHz. This represents the phase state of the (m,n)th metasurface unit in the optimal coding pattern.

[0166] Phase PM of the main lobe in the 5GHz band 5G :

[0167]

[0168] Find the metasurface unit set TU in the 2.4 GHz band. 2.4G and the metasurface unit TU in the 5GHz band 5G The intersection TU serves as at least one metasurface unit in the dual-frequency programmable metasurface structure that has little or no negative impact on the main lobe.

[0169] Furthermore, the specific implementation functions of each functional module in the Sub-6 wireless network communication enhancement device based on dual-frequency programmable metasurface in this application embodiment are consistent with the specific implementation methods in the method embodiment, and will not be described in detail again.

[0170] To verify the effectiveness of the method in this application, the Sub-6 wireless network communication enhancement method based on dual-frequency programmable metasurfaces is evaluated from the following six aspects: (1) Metasurface working concept diagram; (2) Metasurface unit structure diagram; (3) Unit optimization results; (4) Beam scanning results of different frequency bands; (5) Dual-frequency concurrent beamforming signal gain enhancement results; (6) IoT device throughput enhancement results.

[0171] (1) Working concept diagram of metasurface

[0172] Figure 4 A conceptual diagram of a dual-frequency programmable metasurface structure is shown. This metasurface structure can simultaneously redirect incident signals in the 2.4 GHz and 5 GHz bands toward a target direction, achieving beamforming and enhancing communication capabilities.

[0173] (2) Metasurface unit structure diagram

[0174] Figure 2 The diagram shows the structure of a metasurface unit, with two PIN diodes facing opposite directions placed on the upper layer, as shown in (b). The bias current generated by the DC voltage regulator flows from the bias line and through two vertical vias to the surface mount. The current then flows through the PIN diodes to the GND line. Under different DC voltage levels, each PIN diode switches to an "ON" or "OFF" state. Depending on the sign of the bias current, the metasurface unit introduces... The phase shift.

[0175] (3) Unit optimization results

[0176] Figure 5 A schematic diagram of the reflection phase and reflection coefficient of the metasurface unit is shown, where (a) is the reflection phase in the 2.4 GHz band; (b) is the reflection phase in the 5 GHz band; (c) is the reflection coefficient in the 2.4 GHz band; and (d) is the reflection coefficient in the 5 GHz band. The horizontal axis represents the frequency range, and the vertical axis represents the phase and reflection coefficient, respectively. It can be observed that the phase difference between each state is approximately 2 / π in both the 2.4 GHz and 5 GHz bands. Furthermore, the diagram shows that the reflection coefficient at each stage is consistently above 0.7 in both bands, indicating that each state has a minimal impact on the power of the reflected signal. Therefore, the final metasurface unit can be considered as a 2-bit phase shifter.

[0177] (4) Beam scanning results of different frequency bands

[0178] Figure 6Signal intensity maps at different scanning angles for different frequency bands are shown, where (a) is the signal intensity map of the 2.4 GHz band at different scanning angles, and (b) is the signal intensity map of the 5 GHz band at different scanning angles. It can be clearly seen that the effective beamforming range for both 2.4 GHz and 5 GHz is [-60°, 60°]. When the beamforming direction is towards the boundary, although the beamwidth at -3 dB increases and the beamforming gain decreases, the correct directivity is still preserved. Therefore, the effective field of view of the beamforming is [-60°, 60°].

[0179] (5) Results of dual-band concurrent beamforming signal gain enhancement

[0180] Figure 7 The results show the signal gain improvement of dual-band concurrent beamforming under different target directions. (a) is a schematic diagram of the scene layout, and (b) is the experimental results of SNR improvement. Two transmitters operating at 2.4 GHz and 5 GHz were fixed in two different locations, and two corresponding receivers were moved to nine different locations, as detailed in (a). Measurements were then collected to calculate the SNR improvement without the metasurface structure. The results show that the communication enhancement method based on dual-band programmable metasurfaces proposed in this application can simultaneously improve the SNR of two concurrent wireless links. For example, for 2.4 GHz and 5 GHz, average SNR improvements of 9.01 dB and 12.08 dB can be achieved, respectively. This indicates that the communication enhancement method based on dual-band programmable metasurfaces proposed in this application can be well applied to dual-band concurrent wireless transmission.

[0181] (6) Results of IoT device throughput improvement

[0182] Figure 8 The diagrams show the throughput improvement effects of IoT devices operating at different frequencies and with different protocols. (a) shows the deployment layout, and (b) shows the throughput results, where A through G represent different protocols. Various commercial IoT devices operating at different frequency bands (2.4GHz and 5GHz) and following various protocols were tested in an NLoS (Non-Line of Sight) corner scenario. The TCP (Transmission Control Protocol) throughput of the ESP32 chip was measured using iperf (a network performance testing tool), and WARPv3 was measured using the WARPLab environment. The minimum, median, and maximum throughput gains are 115%, 137%, and 249%, respectively, indicating that the metasurface structure is universally applicable to different operating protocols and frequencies.

[0183] In summary, this application significantly reduces hardware and control costs while simultaneously achieving satisfactory high beamforming gain across both frequency bands of Sub-6 ISM. The communication enhancement method based on a dual-frequency programmable metasurface in this application enables concurrent beamforming across dual frequency bands, allowing inexpensive IoT devices operating on different frequency bands and protocols to possess beamforming capabilities, while also exhibiting high area efficiency.

[0184] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for enhancing communication in a Sub-6 wireless network based on a dual-frequency programmable metasurface, characterized in that, include: A dual-frequency programmable metasurface structure is constructed, comprising multiple metasurface units, each of which can generate resonant frequencies in two frequency bands and four phase values. The optimal coding mode for dual-band beamforming is determined for the dual-frequency programmable metasurface structure under different incident and exit angles. Identify at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode; Based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, a coding mode that can provide the best communication signal quality is determined as the final coding mode under different incident and exit angles. The relative direction of the target is detected, where the relative direction is the incident angle of the uplink or the exit angle of the downlink, and the final encoding mode corresponding to the relative direction of the target is selected as the encoding mode used for communication. The metasurface unit comprises a top metal square patch, a middle dielectric cube, and a bottom metal layer, wherein the width of the metal square patch is... for The length of the metal square patch for The height of the dielectric cube for ; A groove is etched at the upper left, lower left, upper right, and lower right edges of the metal square patch, and the width of each groove is... for , groove length for ; A rectangular groove is etched between two grooves in the same column along the column direction, and a PIN diode is embedded in each rectangular groove; the two PIN diodes are in an "on" or "off" state at different DC voltage levels, and the combination obtains four states of the metasurface unit to generate four corresponding phase values; Among them, determining the optimal coding mode for dual-frequency programmable metasurface structure to achieve dual-band beamforming under different incident and exit angles includes: Construct the objective function: in, For optimal encoding mode, To determine the theoretical maximum signal strength achievable in the 2.4 GHz band using the optimal phase offset, The theoretical maximum signal strength achieved in the 5GHz band using the optimal phase offset; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure: in, The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, where M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure. The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. Encoding mode The Middle Phase state of each metasurface unit; This indicates a phase calculation; The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure: in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. Encoding mode The Middle Phase state of each metasurface unit; This indicates a phase calculation; Solving the objective function yields the optimal coding mode for dual-band beamforming achieved by the dual-frequency programmable metasurface structure. Among them, at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode includes: Identify metasurface unit sets that have little or no impact on the main lobe in the 2.4 GHz band. : in, The phase of the main lobe in the 2.4 GHz band. This indicates a phase calculation. The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. This indicates a frequency of 2.4GHz. The first in the best encoding mode Phase state of each metasurface unit; Phase of the main lobe in the 2.4 GHz band : in, To determine the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure. Identify metasurface unit sets that have little or no impact on the main lobe in the 5GHz band. : in, The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. This indicates a frequency of 5GHz. The first in the best encoding mode Phase state of each metasurface unit; Phase of the main lobe in the 5GHz band : Find the set of metasurface units in the 2.4 GHz band. and the metasurface unit set in the 5GHz band intersection As at least one metasurface unit in the dual-frequency programmable metasurface structure that has little or no negative impact on the main lobe; Specifically, based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, a coding mode capable of providing optimal communication signal quality is determined as the final coding mode for different incident and exit angles, including: For each set of incident and exit angles corresponding to the optimal coding mode, the phase state of at least one metasurface unit in the optimal coding mode that has little or no negative impact on the main lobe is changed to obtain multiple updated coding modes. Among the multiple updated encoding modes, the encoding mode that can provide the best communication signal quality is determined as the final encoding mode.

2. The method as described in claim 1, characterized in that, Solving the objective function includes: The objective function is solved using a genetic algorithm. During the solution process, the coding mode of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength implemented in the 2.4 GHz band is used. The coding mode of the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength achieved in the 5GHz band. As the initial chromosome in the initial population of the genetic algorithm.

3. A Sub-6 wireless network communication enhancement device based on a dual-frequency programmable metasurface, characterized in that, include: A dual-frequency programmable metasurface structure, comprising multiple metasurface units, each of which can generate resonant frequencies in two frequency bands and four phase values; The optimal coding mode determination module is used to determine the optimal coding mode for the dual-frequency programmable metasurface structure to achieve dual-frequency beamforming under different incident and exit angles. The negative impact metasurface unit determination module is used to determine at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode. The final coding mode determination module is used to determine the coding mode that can provide the best communication signal quality based on the optimal coding mode and at least one metasurface unit that has little or no negative impact on the main lobe, as the final coding mode under different incident and exit angles. The communication coding mode determination module is used to detect the incident angle or exit angle corresponding to the target, and select the final coding mode corresponding to the incident angle or exit angle corresponding to the target as the coding mode used for communication. The optimal encoding mode determination module is further configured to: Construct the objective function: in, For optimal encoding mode, To determine the theoretical maximum signal strength achievable in the 2.4 GHz band using the optimal phase offset, The theoretical maximum signal strength achieved in the 5GHz band using the optimal phase offset; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure. The intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure; The intensity of the 2.4 GHz signal reflected by the dual-frequency programmable metasurface structure: in, The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. For metasurface units along the emission angle The amplitude of the reflected 2.4 GHz signal, where M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure. The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 2.4GHz band is given. Encoding mode The Middle Phase state of each metasurface unit; This indicates a phase calculation; Calculate the intensity of the 5GHz signal reflected by the dual-frequency programmable metasurface structure: in, To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. For metasurface units along the emission angle The amplitude of the reflected 5GHz signal, The coding mode for the dual-frequency programmable metasurface structure corresponding to the theoretical maximum signal strength realized in the 5GHz band. Encoding mode The Middle Phase state of each metasurface unit; This indicates a phase calculation; Solving the objective function yields the optimal coding mode for dual-band beamforming achieved by the dual-frequency programmable metasurface structure. The negative impact metasurface unit determination module is also used for: Identify metasurface unit sets that have little or no impact on the main lobe in the 2.4 GHz band. : in, The phase of the main lobe in the 2.4 GHz band. This indicates a phase calculation. The angle of incidence required to generate a 2.4 GHz signal. The emission angle of the 2.4 GHz signal reflected by the metasurface unit is given. This indicates a frequency of 2.4GHz. The first in the best encoding mode Phase state of each metasurface unit; Phase of the main lobe in the 2.4 GHz band : in, To determine the phase, M is the number of rows of metasurface units in the dual-frequency programmable metasurface structure, and N is the number of columns of metasurface units in the dual-frequency programmable metasurface structure. Identify metasurface unit sets that have little or no impact on the main lobe in the 5GHz band. : in, The phase of the main lobe in the 5GHz band. To generate the incident angle for a 5GHz signal, The emission angle of the 5GHz signal reflected by the metasurface unit. This indicates a frequency of 5GHz. The first in the best encoding mode Phase state of each metasurface unit; Phase of the main lobe in the 5GHz band : Find the set of metasurface units in the 2.4 GHz band. and the metasurface unit set in the 5GHz band intersection As at least one metasurface unit that has little or no negative impact on the main lobe under the optimal coding mode; The metasurface unit comprises a top metal square patch, a middle dielectric cube, and a bottom metal layer, wherein the width of the metal square patch is... for The length of the metal square patch for The height of the dielectric cube for ; A groove is etched at the upper left, lower left, upper right, and lower right edges of the metal square patch, and the width of each groove is... for , groove length for ; A rectangular groove is etched between two grooves in the same column along the column direction, and a PIN diode is embedded in each rectangular groove; the two PIN diodes are in an "on" or "off" state at different DC voltage levels, and the combination obtains four states of the metasurface unit to generate four corresponding phase values; The final encoding mode determination module is further configured to: For each set of incident and exit angles corresponding to the optimal coding mode, the phase state of at least one metasurface unit in the optimal coding mode that has little or no negative impact on the main lobe is changed to obtain multiple updated coding modes. Among the multiple updated encoding modes, the encoding mode that can provide the best communication signal quality is determined as the final encoding mode.

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