Interference Optimization Method for Overlapping Regions between RIS-Based Wireless Access Points

Abstract

This application relates to the field of mobile communication technologies, and particularly to an interference optimization method for overlapping regions between wireless access points based on RIS, including determining user terminals in the overlapping regions between multiple wireless access points; performing grouping processing on the user terminals in the overlapping regions to obtain a grouping result; determining a set of wireless access points and user terminals for cooperative transmission, and performing superposition coding processing on the data to be transmitted by the wireless access points within the set of wireless access points to obtain the superposition coded data of each wireless access point; configuring the beamforming of the wireless access points and the beamforming reflected by RIS; the wireless access points controlling the beamforming reflected by RIS to send the superposition coded data to the user terminals for cooperative transmission; and the user terminals for cooperative transmission performing successive interference cancellation decoding on the received superposition coded data. This application is beneficial to eliminating the interference received by the user terminals in the overlapping regions, reducing the signaling overhead of interference coordination, reducing the delay, and improving the spectrum efficiency.

Description

Technical Field

[0001] This application relates to the field of mobile communication technologies, and particularly to an interference optimization method for overlapping areas between wireless access points based on RIS. Background Art

[0002] Mobile communication is an industry that is constantly evolving and innovating. Mobile communication involves multiple aspects such as wireless communication technologies, network architectures, mobile devices, service providers, etc. Mobile communication is closely related to our lives. Mobile communication devices for providing networks to mobile users are installed in communities. With the passage of time, community users have higher and higher requirements for the data rate and delay of the network. Wireless networks can meet the needs of mobile users for higher data rates and lower delays. However, the high frequency of wireless access points in wireless networks and the densification of wireless networks lead to increasingly serious and dynamic interference between wireless access points. Therefore, it is necessary to manage the wireless access points of the wireless network to reduce interference. Generally, wireless interference management can be carried out from dimensions such as time domain, frequency domain, power domain, and spatial domain.

[0003] In related technologies, interference between wireless access points (Transmission Reception Point: TRP) generally occurs in the overlapping areas covered by wireless access points. Users in the overlapping areas can receive signals from multiple wireless access points simultaneously, and the wireless interference is relatively serious. Wireless interference management has proposed partial frequency reuse (FFR) technology and soft frequency reuse (SFR) in the frequency domain to solve the interference problem between wireless access points through spectrum planning. However, spectrum partitioning technology cannot meet the dynamic environment. Or, the inter-cell interference coordination (ICIC) technology is used to solve the interference problem between wireless access points. ICIC negotiates the use of spectrum resources through signaling interaction between cells, but this method will bring problems of excessive signaling overhead and excessive delay in the case of wireless network densification, and the spectrum utilization efficiency is not high.

[0004] Therefore, how to efficiently perform dynamic interference management in the overlapping areas between wireless access points is an urgent problem to be solved. Summary of the Invention

[0005] This application aims to at least solve one of the technical problems existing in the prior art. To this end, an embodiment of this application provides an interference optimization method for overlapping areas between wireless access points based on RIS, which is beneficial to eliminating the interference received by user terminals in the overlapping areas, reducing the signaling overhead of interference coordination and reducing the delay, and at the same time improving the spectrum efficiency.

[0006] In a first aspect, the present application proposes an interference optimization method for overlapping areas between RIS-based wireless access points, including:

[0007] Determine user terminals in the overlapping areas between multiple wireless access points;

[0008] Group the user terminals in the overlapping areas to obtain a grouping result;

[0009] Based on the grouping result, determine a set of wireless access points and user terminals for cooperative transmission, and perform superposition coding processing on the data to be transmitted by each wireless access point in the set of wireless access points to obtain superposition coding data for each wireless access point;

[0010] Configure beamforming of the wireless access points corresponding to the grouping result and beamforming of RIS reflection;

[0011] The wireless access points in the set of wireless access points control the beamforming of RIS reflection to send the superposition coding data to the user terminals for cooperative transmission;

[0012] The user terminals for cooperative transmission perform serial interference cancellation decoding on the received superposition coding data to eliminate signal interference from redundant user terminals.

[0013] The technical solution of the first aspect of the present application at least has one of the following advantages or beneficial effects: identifying user terminals in the overlapping area between multiple wireless access points in a wireless network, and performing grouping processing on the user terminals in the overlapping area to obtain a grouping result; determining a set of wireless access points for coordinated transmission and corresponding user terminals based on the grouping result, so as to perform superposition coding on the data of the user terminals for coordinated transmission, and each wireless access point in the set of wireless access points sends the superposition coded data of the user terminals for coordinated transmission in the same time-frequency resource, improving the spectrum efficiency. Configuring beamforming of the wireless access points corresponding to the grouping result and beamforming of RIS reflection, and the beamforming of RIS reflection can compensate for signal fading and distortion introduced by factors such as space loss and multipath effect in the wireless propagation process of the user terminal signal, and at the same time reduce the interference between co-channel users; each wireless access point in the set of wireless access points sends the superposition coded data to the user terminals for coordinated transmission based on the beamforming of RIS reflection, constructs the channel environment of the users in the overlapping area of the wireless access points by using the beamforming of RIS reflection, and non-orthogonal multiple access cooperation is adopted between the wireless access points in the set of wireless access points, which is beneficial to eliminating the interference received by the user terminals in the overlapping area, reducing the signaling overhead of interference coordination and reducing the delay; the user terminals for coordinated transmission perform successive interference cancellation decoding on the received superposition coded data to eliminate the signal interference of redundant user terminals, further eliminating the interference received by the user terminals in the overlapping area, and improving the accuracy of the decoded data obtained by the user terminal successive interference cancellation decoding.

[0014] According to some embodiments of the present application, when the received power of the reference signal measured by the user terminal for at least one wireless access point in the wireless network is greater than a preset threshold, the current wireless access point is added to the service point set of the user terminal;

[0015] When the size of the service point set of the user terminal is greater than 1, it is confirmed that the user terminal belongs to the user terminal in the overlapping area.

[0016] According to some embodiments of the present application, the grouping process for the user terminals in the overlapping area to obtain a grouping result includes:

[0017] Determining the service point sets of each user terminal in the overlapping area;

[0018] Classifying user terminals with two or more identical service points into the same group to obtain a grouping result;

[0019] Taking the set of identical service points as the set of wireless access points for coordinated transmission, and taking the user terminals classified into the same group as the user terminals for coordinated transmission to obtain a grouping result.

[0020] According to some embodiments of the present application, after determining the grouping result, beamforming of RIS reflection is determined according to the priorities of the user terminals for cooperative transmission;

[0021] Beamforming of the radio access points in the radio access point set for the cooperative transmission is determined according to the sum rate of the user terminals for the cooperative transmission.

[0022] According to some embodiments of the present application, the priorities of the user terminals for the cooperative transmission are determined,

[0023] and the phases of the corresponding RISs are configured according to the priorities of the user terminals for the cooperative transmission, such that the channels of the user terminals with higher priorities are better than those of the user terminals with lower priorities, that is, satisfying

[0024]

[0025] where h k is the channel information of the high-priority terminal user k, and h l is the channel information of the low-priority terminal user l, is the noise power of the user terminal k, is the noise power of the user terminal l.

[0026] According to some embodiments of the present application, the configuring the phases of the corresponding RISs according to the priorities of the user terminals for the cooperative transmission includes:

[0027] Dividing the number of RIS units for high-priority user terminals and the number of RIS units for low-priority user terminals based on the number of user terminals in the grouping result. The number of user terminals is |Ψ g |, the number of RIS units for high-priority user terminals is the number of RIS units for low-priority user terminals is where N is the number of RIS units;

[0028] Allocating the RIS units with the largest channel intensity values to the high-priority user terminals, so that the reflection channels from the RIS units to the high-priority user terminals are in the same phase as the reflection channels with the maximum channel gain of the high-priority user terminals, obtaining the phases of the RIS units. The phases of the RIS units are represented by the following formula:

[0029]

[0030] where θ n is the phase of the RIS unit n, is the reflection channel, and g max,k is the reflection channel with the maximum channel gain.

[0031] According to some embodiments of the present application, determining the beamforming of the wireless access points in the wireless access point set for the cooperative transmission according to the sum rate of the user terminals for the cooperative transmission includes:

[0032] Maximize the sum rate of the user terminals for the cooperative transmission in the packet, and determine the beamforming of the wireless access points in the wireless access point set for the cooperative transmission through an optimization model, where the optimization model is represented by the following formula:

[0033]

[0034] ‖ω i ‖ 2 ≤P i , i ∈ Ω g

[0035] Wherein, is the maximum value of the sum rate of the user terminals, γ k is the signal-to-interference-plus-noise ratio of user terminal k, P i is the transmission power of wireless access point i, ω i is the beamforming of wireless access point i;

[0036] The signal-to-interference-plus-noise ratio of user terminal k is represented by the following formula:

[0037]

[0038] Wherein, g RIS,k is the channel gain from the RIS to user terminal k, h i,RIS is the channel gain from wireless access point i to the RIS, h i,k is the channel gain from wireless access point i to user terminal k, ω i is the beamforming of wireless access point i, ω j is the beamforming of wireless access point j, is the noise power of user terminal k;

[0039] The signal-to-interference-plus-noise ratio of user terminal l is represented by the following formula:

[0040]

[0041] Wherein, g RIS,l is the channel gain from the RIS to user terminal l, h i,RIS is the channel gain from wireless access point i to the RIS, h i,l is the channel gain from wireless access point i to user terminal l, h j,RIS TRP is the channel gain from wireless access point j to the RIS, h j,lThe channel gain from the wireless access point j to the user terminal l, g RIS,k The channel gain from the RIS to the user terminal k, h i,k The channel gain from the wireless access point i to the user terminal k, ω i The beamforming of the wireless access point i, ω j The beamforming of the wireless access point j, The noise power of the user terminal l.

[0042] According to some embodiments of the present application, to maximize the sum rate of the user terminals in the cooperative transmission, the beamforming of the wireless access points in the set of wireless access points for the cooperative transmission and the beamforming of the reflection of the RIS are jointly determined through a joint optimization model, and the joint optimization model is represented as follows:

[0043]

[0044] ‖ω i ‖ 2 ≤P i , i ∈ Ω g

[0045] where γ k is the signal-to-interference-plus-noise ratio of the user terminal k, is the noise power of the user terminal k, is the noise power of the user terminal l, h k is the channel information of the high-priority terminal user k, h l is the channel information of the low-priority terminal user l, ω i is the beamforming of the wireless access point i in the set of wireless access points for the cooperative transmission, and Φ is the beamforming of the reflection of the RIS.

[0046] According to some embodiments of the present application, after the beamforming of the wireless access points corresponding to the configuration and the beamforming of the reflection of the RIS corresponding to the grouping result, it further includes:

[0047] Sending time-frequency resources and data processing mode information to the user terminals in the cooperative transmission, so that the user terminals in the cooperative transmission perform successive interference cancellation decoding on the received superimposed coded data according to the time-frequency resources and data processing mode information to eliminate the signal interference of the redundant user terminals.

[0048] According to some embodiments of the present application, when the data processing mode is superimposed coding successive interference cancellation, the data of the user terminals with low priority on the time-frequency resources is determined during the successive interference cancellation decoding in the user terminals in the cooperative transmission;

[0049] Eliminate the data reconstruction signal of the user terminal with a lower priority from the received signal, and decode the received signal after elimination of the signal of the user terminal with a lower priority after reconstruction.

[0050] Other features and advantages of the present application will be described in the subsequent specification, and will, in part, be obvious from the specification, or be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the structures specifically pointed out in the specification, claims, and drawings. Brief Description of the Drawings

[0051] Figure 1 is a flowchart of an interference optimization method for an overlapping area between RIS-based wireless access points provided by an embodiment of the present application;

[0052] Figure 2 is a flowchart of another interference optimization method for an overlapping area between RIS-based wireless access points provided by an embodiment of the present application;

[0053] Figure 3 is a flowchart of a method for grouping user terminals in an overlapping area to obtain a grouping result provided by an embodiment of the present application;

[0054] Figure 4 is a flowchart of another interference optimization method for an overlapping area between RIS-based wireless access points provided by an embodiment of the present application;

[0055] Figure 5 is a flowchart of another interference optimization method for an overlapping area between RIS-based wireless access points provided by an embodiment of the present application;

[0056] Figure 6 is a schematic structural diagram of a controller provided by an embodiment of the present application. Detailed Description of the Embodiments

[0057] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Additionally, the features, operations, or characteristics described in the specification can be combined in any appropriate manner to form various embodiments. At the same time, the steps or actions in the method description can also be reordered or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0058] In the description of this application, "several" means one or more, "multiple" means more than two, and understandings such as "greater than", "less than", and "exceeding" do not include the corresponding number, while understandings such as "above", "below", and "within" include the corresponding number. If "first" and "second" are described, they are only used to distinguish technical features and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features or the sequence of the indicated technical features.

[0059] The serial numbers assigned to components in this article, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meaning. And the "connection" and "coupling" mentioned in this application, unless otherwise specified, both include direct and indirect connection (coupling).

[0060] Mobile communication is an industry that is constantly developing and innovating. Mobile communication involves multiple aspects such as wireless communication technology, network architecture, mobile devices, and service providers. Mobile communication is closely related to our lives. Mobile communication devices for providing networks for mobile users are installed in the community. With the changes of the times, the requirements of community users for the data rate and latency of the network are getting higher and higher. The wireless network can meet the needs of mobile users for higher data rates and lower latencies. However, the high frequency of wireless access points and the densification of the wireless network in the wireless network will lead to increasingly serious and dynamic interference between wireless access points. Therefore, it is necessary to manage the wireless access points of the wireless network to reduce interference. Usually, wireless interference management can be carried out from dimensions such as time domain, frequency domain, power domain, and space domain.

[0061] In the related art, the interference between wireless access points (Transmission Reception Point: TRP) generally occurs in the overlapping area covered by the wireless access points. Users in the overlapping area can receive signals from multiple wireless access points simultaneously, and the wireless interference is relatively serious. Wireless interference management has proposed partial frequency reuse (Fractional Frequency Reuse, FFR) technology and soft frequency reuse (Soft Frequency Reuse, SFR) in the frequency domain to solve the interference problem between wireless access points through spectrum planning. However, the spectrum division technology cannot meet the dynamic environment. Or, the inter-cell interference coordination (Inter Cell Interference Coordination: ICIC) technology is used to solve the interference problem between wireless access points. ICIC negotiates the use of spectrum resources through signaling interaction between cells, but this method will bring problems of excessive signaling overhead and excessive latency in the case of wireless network densification, and the spectrum utilization efficiency is not high.

[0062] Therefore, how to efficiently perform dynamic interference management in the overlapping areas between wireless access points is an issue that urgently needs to be solved.

[0063] Based on this, the embodiments of the present application provide an interference optimization method for the overlapping areas between RIS-based wireless access points, which is beneficial to eliminating the interference suffered by user terminals in the overlapping areas, reducing the signaling overhead of interference coordination and the delay, and improving the spectrum efficiency at the same time.

[0064] The following further elaborates on the present application with reference to the accompanying drawings.

[0065] Refer to Figure 1 , Figure 1 is a flowchart of an interference optimization method for the overlapping areas between RIS-based wireless access points provided by the embodiments of the present application, including steps S100 to S600. Specifically,

[0066] Step S100: Determine the user terminals in the overlapping areas between multiple wireless access points;

[0067] Step S200: Group the user terminals in the overlapping areas to obtain a grouping result;

[0068] Step S300: Based on the grouping result, determine the set of wireless access points and user terminals for cooperative transmission, and perform superposition coding processing on the data to be transmitted by each wireless access point in the set of wireless access points to obtain the superposition coding data of each wireless access point;

[0069] Step S400: Configure the beamforming of the wireless access points corresponding to the grouping result and the beamforming of the RIS reflection;

[0070] Step S500: The wireless access points in the set of wireless access points control the beamforming of the RIS reflection to send the superposition coding data to the user terminals for cooperative transmission;

[0071] Step S600: The user terminals for cooperative transmission perform serial interference cancellation decoding on the received superposition coding data to eliminate the signal interference of redundant user terminals.

[0072] In some embodiments of the present application, the interference optimization method for the overlapping area between RIS-based wireless access points includes: First, determine the user terminals in the overlapping area between multiple wireless access points in the wireless network, and group the user terminals in the overlapping area to obtain a grouping result; Then, based on the grouping result, determine the set of wireless access points for cooperative transmission and the corresponding user terminals, so as to perform superposition coding on the data of the user terminals for cooperative transmission, and each wireless access point within the set of wireless access points transmits the superposition-coded data of the user terminals for cooperative transmission in the same time-frequency resource, improving the spectral efficiency. Configure the beamforming of the wireless access points corresponding to the grouping result and the beamforming reflected by the RIS. The beamforming reflected by the RIS can compensate for the signal fading and distortion introduced by factors such as spatial loss and multipath effect during the wireless propagation of the user terminal signal, and at the same time reduce the interference between co-channel users; Each wireless access point in the set of wireless access points sends the superposition-coded data to the user terminals for cooperative transmission based on the beamforming reflected by the RIS. The beamforming reflected by the RIS is used to construct the channel environment of the users in the overlapping area of the wireless access points. Non-orthogonal multiple access cooperation is adopted between the wireless access points in the set of wireless access points, which is beneficial to eliminating the interference received by the user terminals in the overlapping area, reducing the signaling overhead of interference coordination, and reducing the delay; The user terminals for cooperative transmission perform successive interference cancellation decoding on the received superposition-coded data to eliminate the signal interference of redundant user terminals, further eliminating the interference received by the user terminals in the overlapping area, and improving the accuracy of the decoded data obtained by the user terminals through successive interference cancellation decoding.

[0073] Refer to Figure 2 , Figure 2 FIG. is a flowchart of another interference optimization method for the overlapping area between RIS-based wireless access points provided by an embodiment of the present application, including steps S10 to S20. Specifically,

[0074] Step S10: When the received power of the reference signal measured by the user terminal for at least one wireless access point in the wireless network is greater than a preset threshold, add the current wireless access point to the service point set of the user terminal;

[0075] Step S20: When the size of the service point set of the user terminal is greater than 1, confirm that the user terminal belongs to the user terminal in the overlapping area.

[0076] In some embodiments of the present application, the interference optimization method for the overlapping area between RIS-based wireless access points further includes determining the user terminals in the overlapping area between multiple wireless access points before determining the user terminals in the overlapping area between multiple wireless access points. The method for determining the user terminals in the overlapping area includes: the user terminal measures the reference signals of each wireless access point in the wireless network, and judges the magnitude relationship between the received power of the reference signals of each wireless access point and a preset threshold. When the received power of the reference signal of the wireless access point measured by the user terminal is greater than the preset threshold, the current wireless access point is added to the service point set of the user terminal; then, calculate the number of elements in the service point set of each user terminal. When the size of the service point set of the user terminal is greater than 1, it is confirmed that the user is a user terminal in the overlapping area. By identifying the user terminals in the overlapping area, it is possible to effectively identify the user terminals that are severely affected by wireless interference. After determining the user terminals in the overlapping area, the present application uses RIS to construct the channel environment of the user terminals in the overlapping area between wireless access points, thereby realizing interference coordination and eliminating the interference received by the user terminals in the overlapping area.

[0077] In some embodiments of the present application, the service point set of the user terminal is obtained by the following formula:

[0078] Ω k ={i;RSRP i,k >RSRP thr}

[0079] Ω k represents the service point set of user terminal k, and RSRP i,k is the received signal strength reference power of wireless access point i measured by user terminal k;

[0080] When the size of the service point set Ω k of user terminal k is greater than 1, then the user terminal k is a user terminal in the overlapping area. Further, based on the measurement of the received power, the channel information of the users in the overlapping area is determined by the following formula:

[0081]

[0082] h i,k is the channel gain from wireless access point i to user terminal k, h j,k is the channel gain from wireless access point j to user terminal k, P i is the transmission power of wireless access point i, P j is the transmission power of wireless access point j, RSRP i,k is the received signal strength reference power of wireless access point i measured by user terminal k, and RSRP j,k is the received signal strength reference power of wireless access point j measured by user terminal k.

[0083] Refer to Figure 3 , Figure 3 which is a flowchart of a method for grouping user terminals in an overlapping area to obtain a grouping result provided by an embodiment of the present application, including steps S210 to S230. Specifically,

[0084] Step S210: Determine the set of service points of each user terminal in the overlapping area;

[0085] Step S220: Classify user terminals with two or more identical service points into the same group;

[0086] Step S230: Use the set of identical service points as the set of wireless access points for coordinated transmission, and use the user terminals classified into the same group as the user terminals for coordinated transmission to obtain a grouping result.

[0087] In some embodiments of the present application, the method for grouping user terminals in an overlapping area to obtain a grouping result includes determining the set of service points of each user terminal in the overlapping area, and then classifying user terminals with two or more identical service points into the same group. The user terminals classified into the same group obtain the corresponding set of wireless access points. Classifying user terminals with two or more identical service points into the same group is beneficial for superposition coding of the data of the user terminals for coordinated transmission, improving the spectrum efficiency. Using the set of identical service points as the set of wireless access points for coordinated transmission, and using the user terminals classified into the same group as the user terminals for coordinated transmission to obtain a grouping result. By grouping and determining the grouping result, the set of wireless access points for coordinated transmission and the corresponding user terminals for coordinated transmission can be determined, which is convenient for superposition coding of the data of the user terminals for coordinated transmission, and each wireless access point in the set of wireless access points transmits the superposition coded data of the user terminals for coordinated transmission in the same time-frequency resource, improving the spectrum efficiency.

[0088] In some embodiments of the present application, the set of identical service points is used as the set of wireless access points for coordinated transmission, and the set of wireless access points is represented by the following formula:

[0089] Ω g =Ω k ∩Ω l

[0090] where, Ω g is the set of wireless access points, Ω k is the set of service points of user terminal k, and Ω l is the set of service points of user terminal l;

[0091] Use the user terminals classified into the same group as the user terminals for coordinated transmission, and the user terminals classified into the same group are represented by the following formula:

[0092] Ψ g = {k, l; |Ω k ∩Ω l |≥2}

[0093] where Ψ g represents the set of user terminals classified into the same group, Ω k is the set of service points of user terminal k, and Ω l is the set of service points of user terminal l.

[0094] Referring to Figure 4 , Figure 4 is a flowchart of another interference optimization method for the overlapping area between RIS-based wireless access points provided by an embodiment of the present application, including steps S240 to S250. Specifically,

[0095] Step S240: After determining the grouping result, determine the beamforming reflected by the RIS according to the priorities of the co-transmitting user terminals;

[0096] Step S250: Determine the beamforming of the wireless access points in the set of co-transmitting wireless access points according to the sum rate of the co-transmitting user terminals.

[0097] In some embodiments of the present application, after determining the grouping result, determine the beamforming reflected by the RIS according to the priorities of the co-transmitting user terminals, and determine the beamforming of the wireless access points in the set of co-transmitting wireless access points according to the sum rate of the co-transmitting user terminals. By controlling the beamforming of the wireless access points and the beamforming reflected by the RIS, and by maximizing the sum rate of the users in the overlapping area, the signaling overhead and delay of interference coordination can be greatly reduced, and the spectral efficiency can be improved.

[0098] In some embodiments of the present application, before determining the beamforming reflected by the RIS according to the priorities of the co-transmitting user terminals, first determine the priorities of the co-transmitting user terminals, and configure the corresponding phases of the RIS according to the priorities of the co-transmitting user terminals, so that the channel of the user terminal with a higher priority is better than the channel of the user terminal with a lower priority, that is, satisfy

[0099]

[0100] where h k is the channel information of the high-priority terminal user k, and h l is the channel information of the low-priority terminal user l, is the noise power of user terminal k, is the noise power of user terminal l.

[0101] Determine the priorities of user terminals corresponding to the set of wireless access points for cooperative transmission, and then configure the phases of the corresponding RIS according to the priorities of the user terminals, so that the channels of user terminals with higher priorities are better than those of user terminals with lower priorities. By configuring the phases of the corresponding RIS according to the priority requirements of user terminals, it is possible to enable user terminals with higher priorities to be assigned to the units of the RIS with the maximum channel strength value.

[0102] In some embodiments of the present application, the interference optimization method for the overlapping area between RIS-based wireless access points further includes: dividing the number of RIS units for high-priority user terminals and the number of RIS units for low-priority user terminals based on the number of user terminals in the grouping result, where the number of user terminals is |Ψ g |, the number of RIS units for high-priority user terminals is the numerical result of the number of RIS units rounded up, and the number of RIS units for low-priority user terminals is the numerical result of rounded down, and N is the number of RIS units;

[0103] Allocate the RIS units with the maximum channel strength value to the high-priority user terminals, so that the reflection channels from these RIS units to the high-priority user terminals are in the same phase as the reflection channels with the maximum channel gain of the high-priority user terminals, and obtain the phases of the RIS units. The phases of the RIS units are represented by the following formula:

[0104]

[0105] where θ n is the phase of the RIS unit, is the reflection channel, and g max,k is the reflection channel with the maximum channel gain.

[0106] By determining the priorities of user terminals corresponding to the set of wireless access points for cooperative transmission and setting the phases of the corresponding RIS according to the priorities of the user terminals, the channels of user terminals with higher priorities are better than those of user terminals with lower priorities. By configuring different phases of the RIS for user terminals with different priorities, the phases of the RIS units and the corresponding channel gains of user terminals with different priorities are adjusted through the beamforming technology of the RIS, so that user terminals with higher priorities can obtain the RIS units with the maximum channel strength value, and user terminals with lower priorities can obtain RIS units with smaller channel strength values, which can compensate for the signal fading and distortion introduced by factors such as space loss and multipath effects in the wireless propagation process of user terminal signals in the overlapping area, and at the same time reduce the interference between co-channel users.

[0107] In some embodiments of the present application, determining the beamforming of the wireless access points in the wireless access point set for cooperative transmission according to the sum rate of the user terminals for cooperative transmission includes:

[0108] Maximize the sum rate of the user terminals for cooperative transmission in the packet, and determine the beamforming of the wireless access points in the wireless access point set for cooperative transmission through an optimization model, where the optimization model is represented by the following formula:

[0109]

[0110] ‖ω i ‖ 2 ≤P i ,i∈Ω g

[0111] Wherein, is the maximum value of the sum rate of the user terminals, γ k is the signal-to-interference-plus-noise ratio of user terminal k, P i is the transmission power of wireless access point i, ω i is the beamforming of wireless access point i;

[0112] The signal-to-interference-plus-noise ratio of user terminal k is represented by the following formula:

[0113]

[0114] Wherein, g RIS,k is the channel gain from the RIS to user terminal k, h i,RIS is the channel gain from wireless access point i to the RIS, h i,k is the channel gain from wireless access point i to user terminal k, ω i is the beamforming of wireless access point i, ω j is the beamforming of wireless access point j, is the noise power of user terminal k; Φ is the reflection phase vector of the RIS, that is, the beamforming of the RIS;

[0115] The signal-to-interference-plus-noise ratio of user terminal l is represented by the following formula:

[0116]

[0117] Wherein, g RIS,l is the channel gain from the RIS to user terminal l, h i,RIS is the channel gain from wireless access point i to the RIS, h i,l is the channel gain from wireless access point i to user terminal l, h j,RIS is the channel gain from wireless access point j to the RIS, h j,l is the channel gain from wireless access point j to user terminal l, gRIS,k is the channel gain from the RIS to user terminal k, h i,k is the channel gain from wireless access point i to user terminal k, ω i is the beamforming of wireless access point i, ω j is the beamforming of wireless access point j, is the noise power of user terminal l, and Φ is the beamforming reflected by the RIS.

[0118] In this application, by controlling the beamforming of the wireless access point and the RIS, the sum rate of the user terminals in the overlapping area can be maximized, thereby greatly reducing the signaling overhead and delay of interference coordination and improving the spectral efficiency.

[0119] It should be noted that for the above sum rate maximization problem, the weighted minimum mean square error (WMMSE) algorithm can be used to convert the weighted sum rate maximization problem into an equivalent weighted mean square error minimization problem, and then the block coordinate descent (BCD) method is used for alternating iterative solution. The embodiments of this application do not limit the solution method for the above sum rate maximization problem.

[0120] In some embodiments of this application, the interference optimization method for the overlapping area between RIS-based wireless access points further includes:

[0121] Calculate the channel information of each user terminal based on the RIS according to the grouping result, and obtain it through the following formula:

[0122]

[0123] where h k is the channel information of terminal user k, h l is the channel information of terminal user l, h i,RIS is the channel gain from wireless access point i to the RIS, h j,RIS is the channel gain from wireless access point j to the RIS, g RIS,k is the channel gain from the RIS to user terminal k, g RIS,l is the channel gain from the RIS to user terminal l, h i,k is the channel gain from wireless access point i to user terminal k, h j,k is the channel gain from wireless access point j to user terminal k, h i,l is the channel gain from wireless access point i to user terminal l, h j,lFor the wireless access point j to the user terminal l, by calculating the channel information of each user terminal based on the RIS according to the grouping result, the beamforming using the RIS reflection is implemented to construct the channel environment of the users in the overlapping area of the wireless access points, which is beneficial to eliminating the interference received by the user terminals in the overlapping area, reducing the signaling overhead of interference coordination, and reducing the delay. Φ is the beamforming of the RIS reflection.

[0124] In another embodiment of the present application, the interference optimization method for the overlapping area between RIS-based wireless access points further includes:

[0125] Maximize the sum rate of the co-transmitting user terminals, and jointly determine the beamforming of the wireless access points in the set of co-transmitting wireless access points and the beamforming of the RIS reflection through a joint optimization model. The joint optimization model is expressed as follows:

[0126]

[0127] ‖ω i ‖ 2 ≤P i , i ∈ Ω g

[0128] where γ k is the signal-to-interference-plus-noise ratio of user terminal k, is the noise power of user terminal k, is the noise power of user terminal l, h k is the channel information of high-priority terminal user k, h l is the channel information of low-priority terminal user l, ω i is the beamforming of wireless access point i in the set of co-transmitting wireless access points, and Φ is the beamforming of the RIS reflection.

[0129] It should be noted that the solution method for maximizing the sum rate of co-transmitting user terminals can adopt the Weighted Minimum Mean Square Error (WMMSE) algorithm, convert the weighted sum rate maximization problem into an equivalent weighted mean square error minimization problem, and then use the Block Coordinate Descent (BCD) method to solve it by alternating iteration. The solution method for the sum rate maximization problem in the embodiments of the present application is not limited.

[0130] Referring to Figure 5 , Figure 5 is the flowchart of another interference optimization method for the overlapping area between RIS-based wireless access points provided by the embodiments of the present application; it includes steps S330 to S340. Specifically,

[0131] Step S330: Perform superposition coding on the data of the co-transmitting user terminals after grouping to obtain superposition-coded data;

[0132] Step S340: Send the superposition-coded data to each wireless access point within the set of wireless access points.

[0133] In some embodiments of the application, the interference optimization method for the overlapping area between RIS-based wireless access points includes, after completing the grouping of user terminals in the overlapping area, performing superposition coding on the data of the co-transmitting user terminals after grouping, which improves the spectral efficiency, and then sending the superposition-coded data to each wireless access point within the set of wireless access points, so that each wireless access point in the set of wireless access points sends the superposition coding to the corresponding co-transmitting user terminals based on the beamforming reflected by the RIS.

[0134] In some embodiments of the present application, the signal transmitted by wireless access point i is represented by the following formula:

[0135] x i =ω i s i

[0136]

[0137] where x i is the signal transmitted by wireless access point i, ω i is the beamforming, s k is the data symbol of terminal user k, and Ψ g is the set of co-transmitting users.

[0138] Each wireless access point sends the superposition-coded data of the user terminals in the same time-frequency resource based on the configured beamforming.

[0139] In some embodiments of the present application, after sending the superposition-coded data to each wireless access point within the set of wireless access points, the interference optimization method for the overlapping area between RIS-based wireless access points further includes sending time-frequency resource and data processing mode information to the co-transmitting user terminals, so that the co-transmitting user terminals perform successive interference cancellation decoding on the received superposition-coded data according to the time-frequency resource and data processing mode information to eliminate the signal interference of redundant user terminals.

[0140] It can be understood that after determining the wireless access points and user terminals for cooperative transmission, the beamforming parameters of each wireless access point and RIS are configured, and the user terminal is notified of the data processing method and time-frequency resources for receiving data. The notification method can be a scheduling response message or downlink control information. Then, the data of the user terminals for cooperative transmission are superposed and encoded to obtain superposed encoded data, and the superposed encoded data are sent to each wireless access point within the wireless access point set. Each wireless access point within the wireless access point set sends the superposed encoded data to the user terminals for cooperative transmission according to the configured beamforming parameters, and sends the time-frequency resources and data processing method information to the user terminals for cooperative transmission, so that the user terminals for cooperative transmission can perform successive interference cancellation decoding on the received superposed encoded data according to the time-frequency resources and data processing method information to eliminate the signal interference of redundant user terminals. By superposing and encoding the data of the users in the overlapping area, the users for cooperative transmission utilize successive interference cancellation to eliminate multi-user interference, greatly reducing the signaling overhead and delay of interference coordination and improving the spectrum efficiency.

[0141] In some embodiments of the present application, the time-frequency resources and data processing method information are sent to the user terminals for cooperative transmission, so that the user terminals for cooperative transmission can perform successive interference cancellation decoding on the received superposed encoded data according to the time-frequency resources and data processing method information. And when the data processing method is superposed encoding successive interference cancellation, the data of the user terminals with low priority on the time-frequency resources are determined during the successive interference cancellation decoding of the user terminals for cooperative transmission. Then, the data of the user terminals with low priority are reconstructed into a signal, the signal of the user terminals with low priority after reconstruction is eliminated from the received signal, and the received signal after elimination is decoded.

[0142] When the user terminals for cooperative transmission perform successive interference cancellation decoding, the data of the user terminals with low priority on the time-frequency resources are determined and the data are reconstructed into a signal; then, the signal of the user terminals with low priority in the reconstructed signal is determined, and the signal of the user terminals with low priority after reconstruction is eliminated, so as to reduce the signal interference of redundant user terminals and achieve interference coordination.

[0143] Refer to Figure 6 , Figure 6FIG. 0 is a schematic structural diagram of a controller 1000 provided by an embodiment of the present application, including a processor 1001, which can be implemented in a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, etc., and is used to execute relevant programs to implement the interference optimization method for overlapping areas between RIS-based wireless access points provided by the embodiments of the present application; a memory 1002, which can be implemented in the form of a read-only memory 1002 (ROM), a static storage device, a dynamic storage device, or a random access memory 1002 (RAM), etc. The memory 1002 can store an operating system and other application programs. When implementing the technical solutions provided by the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 1002 and are called by the processor 1001 to execute the embodiments of the present application; an input / output interface 1003, which is used to implement information input and output; a communication interface 1004, which is used to implement communication interaction between this device and other devices, and can implement communication through a wired method (such as USB, network cable, etc.) or through a wireless method (such as a mobile network, WIFI, Bluetooth, etc.); a bus, which transmits information between various components of the device (such as the processor 1001, the memory 1002, the input / output interface 1003, and the communication interface 1004); where the processor 1001, the memory 1002, the input / output interface 1003, and the communication interface 1004 are communicatively connected to each other inside the device through the bus.

[0144] Those of ordinary skill in the art will understand that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, and their appropriate combinations. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or can be implemented as hardware, or can be implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer-readable storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. The computer-readable storage medium includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technologies, CD-ROM, digital versatile disk (DVD), or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that the communication medium generally contains computer-readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0145] The above is a specific description of the preferred embodiment of the present application, but the present application is not limited to the above embodiments. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present application, and these equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. An interference optimization method for overlapping areas between wireless access points based on RIS, characterized in that: include: Determine user terminals in overlapping areas between multiple wireless access points; performing grouping processing on the user terminals in the overlapping area to obtain a grouping result; Determine a set of wireless access points and user terminals for coordinated transmission based on the grouping result, and perform superposition coding processing on the data to be sent by each wireless access point in the wireless access point set to obtain superposition coded data of each wireless access point; configuring beamforming of the wireless access point and beamforming of RIS reflection corresponding to the grouping result; The wireless access point in the wireless access point set controls the beamforming reflected by the RIS to send the superimposed coded data to the cooperatively transmitted user terminal; The cooperatively transmitted user terminal performs serial interference cancellation decoding on the received superimposed coded data to eliminate signal interference from redundant user terminals.

2. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 1, characterized in that: Also includes: When the received power of the reference signal of at least one wireless access point in the wireless network measured by the user terminal is greater than a preset threshold, adding the current wireless access point to the service point set of the user terminal; When the size of the service point set of the user terminal is greater than 1, it is confirmed that the user terminal belongs to a user terminal in an overlapping area.

3. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 2, characterized in that: The grouping of the user terminals in the overlapping area to obtain a grouping result includes: Determine a service point set for each user terminal in the overlapping area; Classifying user terminals having two or more identical service points into the same group; A set of the same service points is used as a set of wireless access points for cooperative transmission, and user terminals classified into the same group are used as user terminals for cooperative transmission, to obtain a grouping result.

4. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 1, characterized in that: Also includes: After determining the grouping result, determining the beamforming of the RIS reflection according to the priority of the user terminal of the cooperative transmission; The beamforming of the wireless access points of the wireless access point set for the cooperative transmission is determined according to the sum rate of the user terminals for the cooperative transmission.

5. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 4, characterized in that: Also includes: determining the priority of the cooperatively transmitted user terminal, The phase of the corresponding RIS is configured according to the priority of the cooperatively transmitted user terminal, so that the channel of the user terminal with high priority is superior to the channel of the user terminal with low priority, that is, Among them, h k is the channel information of high priority terminal user k, h l is the channel information of low priority terminal user l, is the noise power of user terminal k, is the noise power of user terminal l.

6. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 5, characterized in that: The configuring the phase of the RIS corresponding to the priority of the cooperatively transmitted user terminal includes: The number of RIS units of high-priority user terminals and the number of RIS units of low-priority user terminals are divided based on the number of user terminals in the grouping result, wherein the number of user terminals is |Ψ g |, the number of RIS units of the high priority user terminal is The number of RIS units of the low priority user terminal is Where, N is the number of RIS units; The highest channel strength value is allocated to the high priority user terminal. RIS units to enable the The reflected channel from the RIS unit to the high-priority user terminal is in phase with the reflected channel of the maximum channel gain of the high-priority user terminal, and the phase of the RIS unit is obtained. The phase of the RIS unit is expressed by the following formula: Among them, θ n is the phase of RIS unit n, is the reflection channel, g max,k is the reflection channel with maximum channel gain.

7. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 4, characterized in that: The step of determining the beamforming of the wireless access point of the cooperative transmission wireless access point set according to the sum rate of the cooperative transmission user terminal comprises: The sum rate of the cooperatively transmitted user terminals in the group is maximized, and the beamforming of the wireless access points of the cooperatively transmitted wireless access point set is determined by an optimization model, wherein the optimization model is represented by the following formula: ‖oh i ‖ 2 ≤P i ,i∈Ω g in, is the maximum value of the sum rate of the user terminals, γ k is the signal-to-interference-noise ratio of user terminal k, P i is the transmission power of wireless access point i, ω i is the beamforming of wireless access point i.

8. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 1, characterized in that: Also includes: Maximize the sum rate of the user terminal of the cooperative transmission, and jointly determine the beamforming of the wireless access point of the wireless access point set of the cooperative transmission and the beamforming of the RIS reflection through a joint optimization model, wherein the joint optimization model is expressed as follows: ‖oh i ‖ 2 ≤P i ,i∈Ω g Among them, γ k is the signal-to-interference-noise ratio of user terminal k, is the noise power of user terminal k, is the noise power of user terminal l, h k is the channel information of high priority terminal user k, h l is the channel information of low priority terminal user l, ω i is the beamforming of wireless access point i in the wireless access point set for cooperative transmission, and Φ is the beamforming reflected by RIS.

9. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 1, characterized in that: After the configuration of the beamforming of the wireless access point corresponding to the grouping result and the beamforming of the RIS reflection, the method further includes: Send time-frequency resources and data processing method information to the cooperative transmission user terminal, so that the cooperative transmission user terminal performs serial interference elimination decoding on the received superimposed coded data according to the time-frequency resources and data processing method information to eliminate signal interference from redundant user terminals.

10. The interference optimization method for overlapping areas between wireless access points based on RIS according to claim 9, characterized in that: Also includes: When the data processing mode is superposition coding serial interference cancellation, the data of the user terminal with a low priority on the time-frequency resource is determined when the cooperative transmission user terminal performs serial interference cancellation decoding; The data of the user terminal with a low priority is used to reconstruct a signal, the reconstructed signal of the user terminal with a low priority is eliminated from the received signal, and the eliminated received signal is decoded.

Images