A method for improving performance of a wireless local area network and taking into account fairness of each station

Abstract

The method for improving the performance of a wireless local area network and considering the fairness of each station uses a reconfigurable intelligent surface to improve the performance of a wireless local area network system and consider the centralized control of the fairness of each station; 1) according to the service range of the wireless local area network access point and the relative position of the access point and the reconfigurable intelligent surface, a plurality of control codebooks are designed in advance; 2) scanning, using the same time period of the pre-designed control codebook one by one, and counting the total throughput between the access point and each station during the use of each control codebook; 3) according to the information obtained in the scanning stage, considering the performance of the wireless local area network system and the fairness of each station, calculating the probability P of using each control codebook i ; 4) according to the preset periodic time frequency, selecting one control codebook according to the probability P in each time period i ; 5) in order to adapt to the network demand in time, the probability P of using the control codebook is updated according to the preset update frequency i .

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically to a centralized control method that uses a reconfigurable smart metasurface to improve the performance of a wireless local area network system while ensuring fairness among different sites. Background Technology

[0002] Wireless Local Area Networks (WLANs) under the IEEE 802.11 wireless communication protocol standard have become the primary solution for home wireless device access and network deployment in medium to large enterprises and commercial facilities. Distributed Coordination Function (DCF) is a media access control mechanism in the IEEE 802.11 WLAN standard used to manage access between devices in a wireless network. DCF is a distributed protocol based on Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) mechanism, using a binary backoff mechanism (BEB) to solve multi-user communication problems, reducing collisions between nodes to a certain extent and thus improving communication performance.

[0003] However, since the DCF mechanism is static for each device and does not consider network congestion, it can lead to collisions during network congestion. During continuous collisions and retransmissions, the contention window gradually increases, worsening congestion and potentially causing transmission failure. Therefore, when multiple devices transmit simultaneously, collisions occur, preventing the receiver from decoding the transmitted frames. However, a capture effect may occur at the physical layer: when multiple frames arrive at the receiver with different power levels, the frame with the strongest signal power can be demodulated. Therefore, even with synchronous transmission, a sufficiently large difference in signal power can create a capture effect, allowing the receiver to still successfully receive some data.

[0004] Many existing methods utilize the capture effect and reconfigurable smart metasurfaces to improve the performance of wireless LANs, but most of them suffer from the following drawbacks: 1) They cannot guarantee fairness for stations with lower transmission power, resulting in a poor user experience. 2) They often cannot adjust the power differences between stations in a timely manner according to the different loads of each station, and cannot adapt well to changes in network demands. Summary of the Invention

[0005] The purpose of this invention is to improve the performance of a wireless local area network system while ensuring fairness among the stations in scenarios where multiple stations communicate with a single access point simultaneously.

[0006] Technical Solution: To achieve the above objectives, this invention proposes a method to improve the performance of wireless local area networks (WLANs) while ensuring fairness among all sites. It utilizes a reconfigurable smart metasurface and a centralized control method that leverages the capture effect to improve the performance of WLAN systems while ensuring fairness among all sites. This method is suitable for scenarios where multiple sites communicate with a single access point simultaneously.

[0007] The centralized control method includes the following steps: The first step is to pre-design multiple control codebooks based on the service range of the access point and the relative position of the access point and the reconfigurable smart metasurface; The control codebook consists of fixed-length numbers composed of 0s and 1s, representing the high and low levels of the control signals driving the reconfigurable smart metasurface units. Each number in the control codebook corresponds one-to-one with the state of each unit: 0 indicates that the control signal for the corresponding unit is low, while 1 indicates that the control signal for the corresponding unit is high. The use of the control codebook, as described later, involves the control board outputting the corresponding control signals to drive the reconfigurable smart metasurface. In this way, the state of each unit on the reconfigurable smart metasurface can be dynamically adjusted using the control codebook, thereby realizing a variety of electromagnetic wave control functions. Understandably, by using a pre-designed control codebook, channel fluctuations are induced between the signal transmission and reception locations to enhance the signal strength of the beam in a specific direction of the wireless LAN, thereby creating a capture effect, reducing the probability of collisions, and improving performance.

[0008] The second step is to perform a scan, using the same time period of the pre-designed control codebook one by one, and to count the total throughput between the access point and each site during the period when each control codebook is used. It should be noted that the present invention does not limit the duration of the above-mentioned time period, which can be set according to the actual network conditions.

[0009] The third step, based on the information obtained during the scanning phase and taking into account both the performance of the wireless LAN system and fairness among different sites, is to calculate the probability of each control codebook being used using the following formula. : ; in, The number of pre-designed control codebooks, For the first The probability that a control codebook is used is called the activation probability. For the second step The total throughput between the access point and each site during the use of the control codebook. This is an adjustment factor used to balance system performance and site fairness; It should be understood that this invention is not limiting. The value; The larger the value, the more it tends to be fair. The smaller the value, the more performance-oriented it is. This can be adjusted continuously to meet different network requirements. This allows for a trade-off between performance and fairness. The aforementioned approach gives each site a certain probability of receiving a power boost.

[0010] The fourth step is to generate a pseudo-random number within a defined range for each time period, based on a preset periodic time frequency. It should be noted that the present invention is not limited to the preset time frequency, and can be set according to the actual network conditions; Furthermore, based on the pseudo-random number, the defined range of the pseudo-random number generation, and the activation probability of each control codebook, a control codebook is selected for use in the following manner: Calculate the cumulative probability: ; in For cumulative probability, the following condition must be met: , , No. The activation probability of each control codebook; Calculation and cumulative probability Related value: ; in, Cumulative probability Associated values; This is the lower bound for pseudo-random numbers; The cumulative probability mentioned above; This is the upper bound for pseudo-random numbers; It should be noted that the cumulative probability and the cumulative probability mentioned above... Related The value is calculated immediately after the activation probability is updated; Finally, based on the generated pseudo-random numbers and ,Sure Select the corresponding control codebook for the given interval.

[0011] Fifth, to adapt to network demands in a timely manner, the activation probability of each control codebook is updated according to a preset update frequency; the following formula is used for calculation: ; in, The number of pre-designed control codebooks, For the first time before the update The activation probability of each control codebook. For the updated version The activation probability of each control codebook. For the fourth step The total throughput between the access point and each site during the use of the control codebook. For adjustment factors; It should be noted that the update frequency of this invention is not limited, but depends on the actual situation and needs.

[0012] After completing the above steps, repeat steps four and five.

[0013] Beneficial Effects: This invention first determines the control codebook based on the service range of the access point and the relative position of the access point and the reconfigurable smart metasurface. Then, each control codebook is used individually, and the total throughput between the access point and each station is calculated during the use of each control codebook. Next, the activation probability of the control codebook is calculated based on the throughput. Finally, a control codebook is randomly selected based on the activation probability, and the activation probability needs to be updated according to a preset update frequency. This invention uses a reconfigurable smart metasurface to induce channel fluctuations between the access point and stations, enhancing signal strength in specific directions to produce a capture effect, reducing the probability of collisions, improving the performance of the wireless LAN system, and ensuring fairness among stations. Attached Figure Description

[0014] Figure 1 This is one application scenario of the present invention; Figure 2 This is the second application scenario of the present invention; Figure 3 This is a structural block diagram of the control panel; Figure 4 This is a simplified flowchart of a specific example of a centralized control scheme. Detailed Implementation

[0015] This invention proposes a centralized control method that uses a reconfigurable smart metasurface to improve the performance of a wireless local area network system while ensuring fairness among all sites.

[0016] To make the objectives, contents, and advantages of the present invention clearer, the following detailed description will be provided in conjunction with the accompanying drawings and exemplary systems.

[0017] Figure 1 , Figure 2 These are two application scenarios, and their biggest difference lies only in: Figure 1 In this scenario, the communication environment between the access point and the site is good, and data frame loss is almost only caused by collisions. Figure 2The communication environment between the scene access point and the stations is poor, and many data frames are lost even without collisions. The systems in both scenes consist of a Field Programmable Gate Array (FPGA) as the control board, a reconfigurable smart metasurface, an access point, and multiple stations.

[0018] The control board contains a serial communication module, a pseudo-random number generation module, and a control codebook output module. The serial communication module receives information from the access point, which includes the activation probability of each control codebook. The pseudo-random number generation module generates a pseudo-random integer within a defined range of 1 to 255 at the beginning of each periodic time interval, i.e., every 0.1 seconds. The control codebook output module selects a control codebook based on the pseudo-random number, the defined range, and the activation probability of each control codebook. Then, based on the control codebook, the control board's I / O ports output corresponding high and low level control signals to drive the reconfigurable intelligent metasurface unit, thereby causing channel fluctuations between the signal transmission and reception positions, increasing the signal in a specific direction, and enabling the station in that direction to obtain performance gains.

[0019] A reconfigurable smart metasurface is a planar two-dimensional array, typically composed of a large number of carefully designed electromagnetic units. By applying control signals to the adjustable elements on these units, the electromagnetic properties of these units can be dynamically controlled, thereby enabling programmable active intelligent modulation of spatial electromagnetic waves to form an electromagnetic field with controllable amplitude, phase, polarization, and frequency. The reconfigurable smart metasurface used in this example is an electrically controlled reflective metasurface, operating at a center frequency of 2.4 GHz, which is a wireless communication band, allowing for phase modulation of electromagnetic waves in this band. This example's reconfigurable smart metasurface has 12×12 units, each integrating two PIN diodes. The four voltage levels of the two diodes, 00, 01, 11, and 10 (0 for low level, 1 for high level), correspond to the four phase states of the electromagnetic wave. Using the phase corresponding to voltage level 00 as a reference, the phase differences between the four voltage levels are 0°, 90°, 180°, and 270°, respectively.

[0020] It should be noted that the reconfigurable smart metasurface used in this example has 12×12 units, that is, 12 rows and 12 columns. However, the voltage levels of the 12 units in each column are the same. Therefore, only a 24-bit control codebook is needed. The corresponding control signals are output from the 24 I / O ports of the control board to drive all units of the reconfigurable smart metasurface, thereby realizing the control of electromagnetic waves.

[0021] The functions of the access point are: 1) to communicate with each station in the system and to count the throughput between the access point and each station in real time; 2) to calculate the activation probability of each control codebook based on the throughput between the access point and each station, taking into account the performance of the wireless LAN system and the fairness of the stations, and to send the probability to the control board.

[0022] The role of a station is to communicate with the access point. In this example system, multiple stations send information to the access point simultaneously, and the multiple stations send data packets of fixed size and use a single and identical physical layer rate, but the load will be different.

[0023] To improve the performance of the wireless LAN system while ensuring fairness among all sites, a centralized control method is adopted. The specific steps are as follows: The first step is to pre-design multiple control codebooks and store them in the control board, based on the service range of the access point and the relative position of the access point and the reconfigurable smart metasurface.

[0024] In this example, the access point is on the same horizontal plane as the center of the reconfigurable smart metasurface and is located directly in front of the reconfigurable smart metasurface; according to the generalized Snell's law of reflection: ; in, The angle of reflection, Angle of incidence Let be the wave vector in free space. Let be the refractive index of the medium. This is the phase gradient.

[0025] ; ; in, The wavelength of electromagnetic waves. The frequency of the electromagnetic wave.

[0026] The access point is the receiving end, therefore With an angle of 0° and an electromagnetic wave frequency of 2.4 GHz, different control codebooks are used according to the service range of the access point to generate a phase gradient between the cells of the column-to-column reconfigurable smart metasurface. This enhances the signal strength of electromagnetic waves reflected from the reconfigurable smart metasurface to the access point in a specific incident angle direction, thereby enabling the site in that specific direction to obtain performance gains.

[0027] This example designs four control codebooks, as follows: 101001010100000011111110, enhances the signal strength of electromagnetic waves in the direction with an incident angle of 10°; 100100111001001110010011, enhances the signal strength of electromagnetic waves in the direction of incident angle of 30°; 010010011110011110001101, enhances the signal strength of electromagnetic waves in the direction of incident angle of 50°; 010010001101111000100111, enhances the signal strength of electromagnetic waves in the direction of incident angle of 60°.

[0028] The second step is to send a scan start command from the access point to the control board. After receiving the command, the control board outputs the corresponding control signals one by one according to the pre-stored control code book, driving all units of the reconfigurable smart metasurface for the same time period. In this example, the duration of the time period is 1 second, and the total throughput between the access point and each station during the use of each control code book is counted. It should be understood that the present invention does not limit the specific content of the scan start command or the duration of the aforementioned time period.

[0029] Third, based on the throughput information obtained in the second step, and taking into account both the performance of the wireless LAN system and site fairness, the access point calculates the activation probability of each control codebook using the following formula: ; in, In this example, the number of pre-designed control codebooks is... It is 4. For the first A control codebook is used to control the probability of the reconfigurable smart metasurface, called the activation probability. For the second step The total throughput between the access point and each site during the use of the control codebook. In this example, an adjustment factor is used to balance system performance and site fairness. The value is 0.2.

[0030] It should be noted that, The value is not restricted and should be set according to the actual situation. The larger the value, the more it tends to be fair. The smaller the value, the more performance-oriented it is; this can be improved through continuous adjustment. This allows for a trade-off between performance and fairness.

[0031] Furthermore, the activation probability of each control codebook is sent to the control board via serial communication.

[0032] The fourth step involves the control board generating a pseudo-random number within a defined range at a periodic time frequency, starting every 0.1 seconds. In this example, the pseudo-random number is generated using the LFSR algorithm. The pseudo-random number is an 8-bit wide binary number with a size ranging from 1 to 255, starting with a value of 1. The feedback polynomial is as follows: ; in, For newly generated pseudo-random numbers, This is the pseudo-random number generated last time.

[0033] It should be noted that the present invention is not limited to the preset time frequency and can be set according to the actual network conditions.

[0034] Furthermore, the control codebook output module selects a control codebook to use based on the pseudo-random number, the defined range, and the activation probability of each control codebook, in the following manner: Calculate the cumulative probability: ; in For cumulative probability, the following condition must be met: , ; No. The activation probability of each control codebook.

[0035] Calculation and cumulative probability Related value: ; in, Cumulative probability Associated values; This is the lower bound for pseudo-random numbers; in this example, it is 1. The cumulative probability mentioned above; This is the upper bound of the pseudo-random number; in this example, it is 255. It should be noted that the cumulative probability and the cumulative probability mentioned above... Related The value is calculated immediately after the activation probability is updated; Finally, based on the generated pseudo-random numbers and ,Sure Select the corresponding control codebook for the given interval.

[0036] For example, ; Calculated ;like belong For the interval, select control codebook 1: 101001010100000011111110; Fifth, to adapt to network demands in a timely manner, a probability update is performed every 5 seconds, updating the activation probability of each control codebook using the following formula: ; in, The number of pre-designed control codebooks, For the first time before the update The activation probability of each control codebook is calculated in the third and fifth steps. For the updated version The activation probability of each control codebook. For the fourth step The total throughput between the access point and each site during the use of the control codebook. In this example, as an adjustment factor, The value is 0.2.

[0037] It should be noted that the probability update frequency of this invention is not limited and can be set according to the actual network conditions.

[0038] You only need to repeat steps four and five.

[0039] The above-described examples illustrate only one embodiment of the present invention, and while the description is specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, various modifications and improvements made without departing from the inventive concept fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for improving the performance of a wireless local area network while ensuring fairness among different sites, characterized in that, A centralized control method using reconfigurable smart metasurfaces to improve the performance of wireless LAN systems while ensuring fairness among sites includes the following steps: The first step is to pre-design multiple control codebooks based on the service range of the wireless LAN access point and the relative position of the access point and the reconfigurable smart metasurface. The control codebook is a fixed-length set of 0s and 1s that represents the high and low levels of the control signals driving the reconfigurable smart metasurface units. Each number in the control codebook corresponds one-to-one with the state of each unit: 0 indicates that the control signal of the corresponding unit is low, while 1 indicates that the control signal of the corresponding unit is high. The use of the control codebook, as described later, involves the control board outputting the corresponding control signals to drive all units of the reconfigurable smart metasurface. Using a pre-designed control codebook, channel fluctuations are induced between the signal transmission and reception locations to enhance the signal strength of the beam in a specific direction of the wireless LAN, thereby producing a capture effect: when multiple frames arrive at the receiver at different power levels, the frame with the strongest signal power can be demodulated, reducing the probability of collisions and improving performance. The second step is to perform a scan, using the same time period of the pre-designed control codebook one by one, and to count the total throughput between the access point and each site during the period when each control codebook is used. The third step, based on the information obtained during the scanning phase and taking into account both the performance of the wireless LAN system and fairness among different sites, is to calculate the probability of each control codebook being used. The following formula is used: in, The number of pre-designed control codebooks, For the first The probability that a control codebook is used is called the activation probability. For the second step The total throughput between the access point and each site during the use of the control codebook. w This is an adjustment factor used to balance system performance and site fairness; It should be understood that, w The larger the value, the more it tends to be fair. w The smaller the value, the more performance-oriented it tends to be; this can be adjusted continuously to meet different network requirements. w This approach strikes a balance between performance and fairness, giving each site a certain probability of receiving a power boost. The fourth step is to generate a pseudo-random number within a defined range for each time period, based on a preset periodic time frequency. Based on the pseudo-random numbers, the defined range of pseudo-random number generation, and the activation probability of each control codebook, a control codebook is selected for use in the following manner: Calculate the cumulative probability: in For cumulative probability, the following condition must be met: , , No. The activation probability of each control codebook; Calculation and cumulative probability Related value: in, Cumulative probability Associated values; This is the lower bound for pseudo-random numbers; The cumulative probability mentioned above; This is the upper bound for pseudo-random numbers; It should be noted that the cumulative probability and the cumulative probability mentioned above... Related The value is calculated immediately after the activation probability is updated; Finally, based on the generated pseudo-random numbers and ,Sure Select the corresponding control codebook for the given interval; Fifth, to adapt to network demands in a timely manner, the activation probability of each control codebook is updated according to a preset update frequency; the following formula is used for calculation: in, The number of pre-designed control codebooks, For the first The activation probability of each control codebook. For the second step The total throughput between the access point and each site during the period when the control codebook is used. w This is an adjustment factor used to balance system performance and site fairness; After completing the above steps, repeat steps four and five; A control board is configured, containing a serial port module, a pseudo-random number generation module, and a control codebook output module. The serial port module receives information from the access point, including the activation probability of each control codebook. The pseudo-random number generation module generates a pseudo-random number within a defined range at the beginning of each periodic time interval. The control codebook output module selects a control codebook based on the pseudo-random number, the defined range, and the activation probability of each control codebook. The control board generates a pseudo-random number within a defined range every 0.1 seconds at a periodic time frequency. This induces channel fluctuations between the signal transmission and reception positions, increasing the signal strength in that direction and providing performance gains to stations in that direction. The centralized control method involves the following steps: The first step is to pre-design multiple control codebooks and store them in the control board, based on the service range of the access point and the relative position of the access point and the reconfigurable smart metasurface. The second step is to send a scan start command from the access point to the control board. After receiving the command, the control board outputs the corresponding control signals one by one according to the pre-stored control code book to drive all units of the reconfigurable smart metasurface for the same time period, and calculates the total throughput between the access point and each station during the use of each control code book. Third, based on the throughput information obtained in the second step, and taking into account both the performance of the wireless LAN system and site fairness, the access point calculates the activation probability of each control codebook using the following formula: in, The number of pre-designed control codebooks, For the first The activation probability of each control codebook. For the second step The total throughput between the access point and each site during the use of the control codebook. w This is an adjustment factor used to balance system performance and site fairness; Furthermore, the activation probability of the control codebook is sent to the control board; The fourth step is for the control board to generate a pseudo-random number within a defined range for each time period according to a preset periodic time frequency.

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