CN116722899A - RIS control method, RIS control device and storage medium - Google Patents

RIS control method, RIS control device and storage medium Download PDF

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Publication number
CN116722899A
CN116722899A CN202310820626.6A CN202310820626A CN116722899A CN 116722899 A CN116722899 A CN 116722899A CN 202310820626 A CN202310820626 A CN 202310820626A CN 116722899 A CN116722899 A CN 116722899A
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CN
China
Prior art keywords
ris
target terminal
base station
information
control
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CN202310820626.6A
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Chinese (zh)
Inventor
刘秋妍
李福昌
张忠皓
李佳俊
吕轩
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China United Network Communications Group Co Ltd
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China United Network Communications Group Co Ltd
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Priority to CN202310820626.6A priority Critical patent/CN116722899A/en
Publication of CN116722899A publication Critical patent/CN116722899A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The application discloses a RIS control method, a RIS control device and a storage medium, which relate to the field of wireless communication and can flexibly control RIS and meet the real-time requirements of users. The method comprises the following steps: acquiring communication demand information of at least one target terminal; the target terminal is any one of at least one terminal which uses signals transmitted by the base station and has shielding or attenuation with a direct connection channel of the base station; the communication demand information of the target terminal comprises the minimum communication rate of the target terminal; generating control information based on the communication demand information and RIS channel state information of at least one target terminal; wherein the control information includes an RIS orientation angle; the control information is used for indicating the RIS to adjust the RIS direction based on the RIS direction angle; and sending control information to the RIS.

Description

RIS control method, RIS control device and storage medium
Technical Field
The present application relates to the field of wireless communications, and in particular, to a method and apparatus for controlling RIS, and a storage medium.
Background
The intelligent super surface (reconfigurable intelligent surface, RIS) is composed of a large number of carefully designed electromagnetic units (i.e. reflecting units) arranged, and if control signals are applied to adjustable elements on the electromagnetic units, the electromagnetic properties of the electromagnetic units can be dynamically controlled, so that active intelligent regulation and control of the space electromagnetic waves in a programmable manner are realized, and electromagnetic fields with controllable amplitude, phase, polarization and frequency are formed. Based on the above-mentioned RIS characteristics, RIS is currently applied to improve wireless communication performance. The RIS link propagation loss is however more severe than the conventional communication link loss, for which conventional techniques reduce the RIS link loss by deploying the RIS at a suitable location. The method for reducing RIS link loss by deploying RIS at a proper position has poor flexibility and is difficult to meet the real-time communication requirement of users.
Disclosure of Invention
The application provides a RIS control method, a RIS control device and a storage medium. The RIS can be flexibly controlled, and the real-time requirement of a user is met.
In order to achieve the technical purpose, the application adopts the following technical scheme:
in a first aspect, an embodiment of the present application provides a RIS control method, which is applied to a base station, where the base station is connected to a RIS, and the method includes: acquiring communication demand information of at least one target terminal; the target terminal is any one of at least one terminal which uses signals transmitted by the base station and has shielding or attenuation with a direct connection channel of the base station; the communication demand information of the target terminal comprises the minimum communication rate of the target terminal; generating control information based on the communication demand information and RIS channel state information of at least one target terminal; wherein the control information includes an RIS orientation angle; the control information is used for indicating the RIS to adjust the RIS direction based on the RIS direction angle; the RIS orientation angle is related to the beam forming vector of the target terminal, the minimum communication rate of the target terminal, the signal-to-interference ratio of the target terminal and the maximum transmission power of the base station; the beam forming vector of the target terminal, the signal to interference ratio of the target terminal are related to RIS channel state information, the minimum communication rate of the target terminal and the maximum transmission power of the base station; and sending control information to the RIS.
It can be understood that, in the process of communicating with at least one target terminal, the base station acquires the RIS channel state information and the communication requirement information of the target terminal in real time, and adjusts the RIS direction in real time based on the information, so as to meet the real-time communication requirement of the at least one target terminal, so that the method has higher flexibility.
In one possible implementation manner, before obtaining the communication requirement information of the target terminal, the method further includes: when it is determined that at least one direct connection channel between the terminal and the base station is blocked or attenuated, an opening instruction is sent to the RIS; wherein the open indication is used to indicate RIS open.
It can be understood that, when the switch is set in the RIS, the RIS is in a closed state when the direct connection channel between the base station and the terminal is normal, and is opened when the direct connection channel between the base station and the terminal is normal. This arrangement may save RIS power consumption when the RIS is active or semi-passive.
In another possible implementation, the RIS is oriented at an angle θ 0 Beamforming vector w of kth target terminal with target terminal k Minimum communication rate R of kth target terminal of target terminals k，min Signal-to-interference ratio gamma of kth target terminal of target terminals k And maximum transmission power P of base station max The following calculation formula is satisfied: wherein P is 0 Is an objective function; k represents the number of target terminals, K represents the kth target terminal; the RIS comprises a plurality of reflecting units, u m Is the phase offset of the mth reflection unit of the plurality of reflection units of the RIS; />And representing a preset RIS orientation angle regulation range.
It can be appreciated that the above method for calculating the RIS orientation angle is one possible implementation method, and the method for solving the RIS orientation angle according to the embodiment of the present application is not limited thereto.
In another possible implementation, the RIS channel state information includes: RIS to target terminal channel information r k And base station to RIS channel information G; beamforming vector w of target terminal k Signal-to-interference ratio gamma with target terminal k The following calculation formula is satisfied:
wherein PL is k (θ 0 ) Indicating that the kth target terminal is at theta 0 Loss on path, Φ represents the phase shift matrix, r k The channel information of the kth target terminal from the RIS to the target terminal and the channel information G from the base station to the RIS are represented.
It can be understood that the calculation formula includes the beamforming vector w of the kth target terminal k Signal-to-interference ratio gamma with target terminal k A relationship between them that can help solve the RIS orientation angle.
In another possible implementation, the preset RIS is oriented at an angle θ 0 Regulatory region of (2)Satisfy-> Or satisfy->A discrete adjustable angle set preset in a range; wherein θ AoA，1 Is the angle of the incident wave of the base station to the RIS, < >>Is the maximum angle of the outgoing wave from the RIS to the kth target terminal.
It can be understood that in the embodiment of the present application, based on each target terminal, a regulation and control range is set for the RIS orientation angle, so as to set a certain constraint for solving the RIS orientation angle, which is helpful for solving the optimal RIS orientation angle.
In another possible implementation, the control information further includes: a phase shift matrix; the control information is also used to instruct the RIS to adjust the phase of each reflective element of the RIS based on the phase offset matrix.
It will be appreciated that the phase shift matrix can determine the phase of each reflection unit of the RIS, so as to determine the strength of the signal transmitted by the RIS, so as to achieve the purpose of enhancing the received signal of the target terminal. Meanwhile, the phase shift matrix also determines the value of the RIS orientation angle to a certain extent, so that the embodiment of the application needs to adjust the phase of each reflection unit of the RIS through the phase shift matrix in the control signal.
In another possible implementation, the phase shift matrix Φ includes a phase shift for each reflective element of the RIS; the phase offset of each reflection unit satisfies the following formula: wherein B represents the number of bits and m represents the mth reflection unit.
It can be understood that the above method for solving the phase shift matrix provided in the embodiment of the present application is not limited to this method for solving the phase shift matrix in the embodiment of the present application.
In another possible implementation, the solution method of the objective function includes a continuous convex approximation and an iterative solution method.
It can be appreciated that, since the objective function has non-convexity and each variable is highly coupled, the sub-optimal solution can be usually obtained based on an optimization algorithm, for example, a continuous convex approximation method is adopted to convert the original problem into a convex problem, and iterative solution is performed, so that the solution finally converges to a steady-state solution of the original problem, and an optimal RIS orientation is obtained.
In a second aspect, an embodiment of the present application provides an RIS control apparatus, where the RIS control apparatus is applied to each module of the RIS control method in the first aspect or any possible implementation manner of the first aspect.
In a third aspect, an embodiment of the present application provides an RIS control apparatus, including a memory and a processor. The memory is coupled to the processor; the memory is used to store computer program code, which includes computer instructions. The computer instructions, when executed by a processor, cause the RIS control apparatus to perform the RIS control method as in the first aspect and any one of its possible implementations.
In a fourth aspect, the present application provides a computer-readable storage medium comprising computer instructions. Wherein the computer instructions, when run on the RIS control apparatus, cause the RIS control apparatus to perform the RIS control method as in the first aspect and any one of its possible implementations.
In a fifth aspect, the present application provides a computer program product comprising computer instructions. Wherein the computer instructions, when run on the RIS control apparatus, cause the RIS control apparatus to perform the RIS control method as in the first aspect and any one of its possible implementations.
For a detailed description of the second to fifth aspects of the present application and various implementations thereof, reference may be made to the detailed description of the first aspect and various implementations thereof; moreover, the advantages of the second aspect and the various implementations thereof may be referred to as analyzing the advantages of the first aspect and the various implementations thereof, and will not be described herein.
These and other aspects of the application will be more readily apparent from the following description.
Drawings
FIG. 1 is a schematic diagram of an implementation environment of an RIS control method according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a RIS structure according to an embodiment of the present application;
FIG. 3 is a flowchart of a RIS control method according to an embodiment of the present application;
fig. 4 is a schematic diagram of channel state information according to an embodiment of the present application;
FIG. 5 is a schematic view of an incident wave angle and an emergent wave angle according to an embodiment of the present application;
FIG. 6 is a schematic diagram of another RIS control device according to an embodiment of the present application;
FIG. 7 is a schematic diagram of another RIS control device according to an embodiment of the present application.
Detailed Description
For convenience of understanding, the following will first briefly describe related terms involved in the embodiments of the present application:
(1) Beamforming: a signal processing technique for directionally transmitting and receiving signals using a sensor array. The beamforming technique allows signals at certain angles to obtain constructive interference and signals at other angles to obtain destructive interference by adjusting parameters of the fundamental elements of the phased array. Beamforming can be used for both signal transmitting and signal receiving terminals.
(2) Channel state information (channel state information, CSI), which is the channel properties of a communication link in the field of wireless communications. It describes the attenuation factor of the signal on each transmission path, i.e. the value of each element in the channel gain matrix H, such as signal Scattering (Scattering), environmental attenuation (coding, multipath fading or shadowing fading), distance attenuation (power decay of distance), etc. The CSI may adapt the communication system to the current channel conditions, providing a guarantee for high reliability and high rate communication in a multi-antenna system.
Hereinafter, the terms "first," "second," and "third," etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", or "a third", etc., may explicitly or implicitly include one or more such feature.
In the conventional technology, when the RIS is used for improving the wireless communication performance, the RIS is deployed mainly by selecting a proper position to reduce the IRS link propagation loss. Because the RIS position once determined cannot be changed any more, the method proposed by the traditional technology is difficult to meet the real-time communication requirement of the user and has poor flexibility.
Based on this, the embodiment of the application provides a RIS control method, in which a base station acquires communication requirement information of at least one target terminal in real time, determines an RIS orientation angle based on the communication requirement information of the target terminal and the RIS channel state information, and generates a control signal to control the RIS to adjust the orientation angle. It can be understood that, in the process of communicating with at least one target terminal, the base station acquires the RIS channel state information and the communication requirement information of the target terminal in real time, and adjusts the RIS direction in real time based on the information, so as to meet the real-time communication requirement of the at least one target terminal, so that the method has higher flexibility.
The following describes in detail the implementation of the embodiment of the present application with reference to the drawings.
Referring to fig. 1, a schematic diagram of an implementation environment related to an RIS control method according to an embodiment of the present application is shown. As shown in fig. 1, the implementation environment may include: base station 110, RIS120, and terminal 130.
The base station 110, i.e. the public mobile communication base station, is an interface device for mobile devices to access the internet and is also a form of radio station. The main function of the base station is to provide wireless coverage, i.e. to enable wireless signal transmission between a wired communication network and a wireless terminal. In the embodiment of the present application, the base station 110 provides the wireless signal to the terminal 130.
The RIS120 can control the propagation of electromagnetic waves by changing electromagnetic characteristics by reflection units at the surface. The surface of the RIS120 is a reconfigurable surface, each element of which can change the phase, amplitude or polarization of an incident electromagnetic wave to produce a specific output electromagnetic wave, completing beamforming and beam steering. In the embodiment of the present application, the orientation angle of the RIS120 may be adjusted. When the direct link between the base station 110 and the terminal 130 is blocked, the RIS120 can be used to facilitate data communication between the base station 110 and the terminal 130.
The RIS120 can be classified into a passive type and a semi-passive type. The semi-passive type RIS differs from the passive type RIS in that the surface of the semi-passive type RIS is provided with a dedicated sensor in addition to the reflecting unit, which is capable of sensing the direction of the nearby terminal.
Alternatively, as shown in fig. 2, the RIS120 shown in fig. 2 is a passive RIS including three sub-layers and a RIS controller, and the first, i.e., outermost layer, is formed by printing a plurality of reflective elements on a dielectric substrate, and directly acts on and reflects an incident signal. Each reflecting unit is composed of passive device capacitor, resistor and the like, has small energy consumption and low cost, and can reflect signals independently.
The second layer is typically designed as a layer of copper or other metal plate, the primary function of which is to prevent the signal from penetrating the reflective surface, thereby causing signal attenuation.
The third layer is a control circuit board, and the controller can independently adjust the values of capacitance, resistance and inductance in all the reflection units of the RIS, so that the amplitude or phase of the reflection signal can be adjusted.
The controller may be a field-programmable gate array (FPGA) through which the reflection coefficient (including amplitude and phase) of each reflection unit can be controlled. The RIS controller is used for adjusting the parameters (reflection parameters) of the passive devices in each reflection unit in real time, so that the phase adjustment coefficients of all the reflection units are changed.
Alternatively, the RIS120 has a switch for turning the RIS120 on or off, which may be provided in the controller, or a hardware switch, such as a level, when the level is high, the RIS120 is in an on state, and when the level is low, the RIS120 is in an off state.
The terminal 130, a mobile intelligent terminal device, has the capability of accessing the internet and is generally equipped with various operating systems.
The terminal 130 includes, for example: cell-phone, panel computer, on-vehicle intelligent terminal, smart television or wearable equipment etc..
The terminal 130 is a terminal that is within a coverage area of a wireless communication signal transmitted by the base station 110 and uses the wireless communication signal transmitted by the base station 110. The number of the terminals 130 may be one or more, and the number of the terminals 130 is not limited in the embodiment of the present application.
As shown in fig. 1, the base station 110 and the RIS120 of the embodiment of the present application establish a connection through a wired or wireless link. The base station 110 establishes a connection with the terminal 130 through signals transmitted by the base station 110, and a direct link between the base station 110 and the terminal 130 is blocked by an object such as a building. RIS120 may be deployed between base station 110 and terminal 130.
In one application scenario, base station 110 sends a control instruction containing a phase offset matrix and/or an RIS orientation angle to a controller of RIS120 to cause the controller to adjust the phase of the RIS120 reflective unit and/or the orientation of the RIS.
The following describes the RIS control method provided by the embodiment of the present application:
the RIS control method provided by the embodiment of the present application may be applied to the base station 110. The execution subject of the RIS control method provided by the embodiment of the present application may also be an RIS control device. The RIS control device may be a base station, or a central processing unit (Central Processing Unit, CPU) in the base station, or a control module in the base station for executing the RIS control method. The method provided by the embodiment of the application is exemplified by the base station.
Referring to fig. 3, a flowchart of an RIS control method according to an embodiment of the present application is shown. As shown in fig. 3, the method may include S101-S107.
S101: the base station determines whether a direct connection channel between at least one terminal and the base station is blocked or attenuated.
If there is occlusion or attenuation, then S102 is performed;
if there is no occlusion or attenuation, the process ends.
A terminal is a terminal that is within the coverage of a signal transmitted by a base station and uses the signal transmitted by the base station. The number of the terminals may be one or more. When a plurality of terminals use signals transmitted by the base station, the base station detects direct connection channels of the plurality of terminals respectively.
In one possible implementation, the base station acquires channel state information between the base station and at least one terminal by means of channel estimation to detect whether a direct connection channel between the base station and the at least one terminal is blocked or attenuated.
Channel estimation is a process of estimating characteristics of a channel using various states exhibited by a received signal.
Channel State Information (CSI) represents the propagation characteristics of a communication link that describes the combined effects of scattering, fading, or power attenuation, among other effects, in the channel.
In one example, a base station obtains Channel State Information (CSI) of an uplink by transmitting a pilot signal to a terminal through the uplink, for example: reference signal received power (reference signal receiving power, RSRP) and signal-to-interference plus noise ratio (signal to interference plus noise ratio, SINR), or the terminal acquires downlink channel state information by transmitting a pilot signal to the base station through the downlink and transmits to the base station. The base station estimates whether there is a blocking or attenuation of the direct channel between the base station and the terminal through the channel state information of the uplink or the channel state information of the downlink.
S102 (optional): the base station sends an on indication to the RIS.
Wherein the open indication is used to indicate RIS open.
In one possible implementation, the RIS has a switch that is controllably turned on, and the RIS is turned on or off upon receiving an indication of the base station. Meanwhile, the RIS replies network configuration information to the base station, wherein the network configuration information comprises RIS on-state information.
It can be appreciated that the RIS is opened when there is a blocking or attenuation of the direct channel between the base station and the terminal, and a new communication link can be additionally added outside the direct channel between the base station and the terminal, so as to enhance the strength of the communication signal between the base station and the terminal. The RIS is in a closed state when a direct connection channel between the base station and the terminal is normal, and RIS power consumption can be saved by the arrangement when the RIS is active or semi-passive.
S103: and the base station carries out cascade channel estimation on the RIS to acquire RIS channel state information.
The RIS concatenated channel includes a base station to RIS channel and an RIS to target terminal channel. The RIS channel state information includes base station to RIS channel state information and RIS to target terminal channel state information.
The target terminal is any one of terminals with shielding or attenuation on a direct connection channel with the base station.
In one example, as shown in fig. 4, when there are three target terminals, the RIS channel state information acquired by the base station is base station-to-RIS channel state information G, and RIS channel state information r1, r2, and r3 to the three target terminals, respectively.
For passive RIS, IRS channel state information is estimated by the base station. Specifically, the base station acquires the direction and position information of the RIS, the target terminal sends a pilot signal to the base station, the base station generates a feedback signal based on the position information of the RIS and the current RIS direction angle, the feedback signal is sent to the RIS, the RIS adjusts the reflection coefficient based on a preset codebook, and the feedback signal is reflected to the target terminal, so that the base station acquires RIS channel state information.
For semi-passive RIS, the RIS has a sensing function and can actively sense channels, so that RIS channel state information is estimated by the RIS and sent to the base station. Specifically, the base station acquires the orientation angle and the position information of the current RIS, the target terminal sends a pilot signal to the base station, the base station generates a feedback signal based on the position information of the RIS and the current RIS orientation angle, the feedback signal is sent to the RIS, and the RIS estimates CSI according to the received feedback signal.
S104: the base station acquires the communication requirement information of at least one target terminal.
The communication requirement information of the target terminal comprises the minimum communication rate of the target terminal.
The minimum communication rate of the target terminal is a minimum communication rate that satisfies the execution of the service by the target terminal.
Optionally, the base station acquires communication requirement information of a plurality of target terminals. The plurality of target terminals are terminals having a blocking or fading of a direct connection channel with the base station.
In one example, there are 10 terminals connected to the base station, if the base station detects that there are shielding or attenuation of the direct connection channels between 5 terminals and the base station, the 5 terminals are target terminals, and the base station acquires the communication requirement information of the 5 target terminals.
Because the target terminal is any one of terminals with blocked or attenuated direct-connection channels with the base station, optionally, in S104, the base station obtains the communication requirement information of the target terminals with blocked or attenuated direct-connection channels with all the base stations, and then when the phase adjustment of the reflection unit of the RIS and the direction adjustment of the RIS are performed, the requirement of all the users using the target terminal on the communication signals can be met.
S105: the base station generates control information based on the communication requirement information and RIS channel state information of at least one target terminal.
The control information includes the RIS orientation angle and optionally a phase shift matrix.
The control information is used to instruct the RIS to adjust the orientation of the RIS based on the RIS orientation angle and instruct the RIS to adjust the phase of each reflective element of the RIS based on the phase offset matrix.
The phase shift matrix contains the phase shift of each reflection unit of the RIS.
Specifically, the implementation process of S105 may include S105a-S105d:
s105a: and the base station acquires the signal-to-interference ratio and the beam forming vector of the target terminal.
In one possible implementation, the signal-to-interference ratio and beamforming vector of the target terminal satisfy equations (1), (2) and (3).
Wherein P is 0 Is an objective function; k represents the number of target terminals, K represents the kth target terminal, R k，min Representing the minimum communication rate of the target terminal, gamma k Representing the signal-to-interference ratio of the kth target terminal, G representing the base station to RIS channel information, r k Indicating channel information from RIS to kth target terminal, PL k (θ 0 ) Indicating that the kth target terminal is at theta 0 Loss on path, θ 0 Represents the orientation angle of RIS, phi is the phase shift matrix, P max The maximum transmission power of the base station,
in one example, PL k (θ 0 ) Can be estimated from the RIS concatenated channel state information obtained in S103.
S105b: the base station acquires a phase shift matrix.
The phase shift matrix Φ includes the phase shifts of each of the reflective elements of the RIS.
In one possible implementation, the phase of the RIS reflection unit can only take discrete quantized values, and the quantized bit number is set to B (B is a positive integer), and then the phase offset of the reflection unit of the mth RIS should be as follows:
for example, when B takes 1, for a 1-Bit phase RIS, the reflection elements of the entire RIS are divided into 0 elements and 1 elements, 0 elements: 0 ° reflection phase, 1 unit: 180 deg. reflection phase.
It will be appreciated that increasing the value of the number of bits B described above may increase the accuracy of the phase adjustment of the reflecting element.
S105c: the base station obtains an adjustable angle range of the orientation angle of the RIS.
In one possible embodiment, the RIS is oriented at an angle θ 0 The method meets the following conditions:
as shown in fig. 5, θ AoA，1 Is the angle of the incident wave from the base station to the RIS,is the maximum angle of the outgoing wave from the RIS to the kth target terminal. Since the locations of the different target terminals are different, therefore +.>Related to the position of the kth target terminal.
In another possible implementation, in consideration of the limitation of the actual hardware conditions such that continuous precise regulation of the RIS orientation cannot be achieved, in the above possible implementation, the selection is madeDiscrete adjustable angles in the range as the set of adjustable angles +.>
S105d: the base station obtains the orientation of the RIS.
The base station can establish the following objective function based on the minimum communication rate requirement of a plurality of terminals, the maximum transmission power of the base station side, the phase constraint of the intelligent super surface and the angle constraint of the orientation of the intelligent super surface, and the sum rate:
the constraint condition of the objective function P0 described above satisfies the solving process in S105a to S105 c.
The objective function has non-convexity, and each variable is highly coupled, and usually, a suboptimal solution can be obtained based on an optimization algorithm, for example, a continuous convex approximation method is adopted to convert an original problem into a convex problem, and iterative solution is performed, so that the original problem is finally converged to a steady-state solution of the original problem, and an optimal RIS orientation is obtained, namely, an optimal RIS orientation angle theta 0 is solved.
From the above solving process of S105a to S105d, it can be seen that the RIS orientation angle is solved based on the communication requirement information of k target terminals, so that the RIS orientation angle can comprehensively meet the communication requirements of k target terminals, and the overall communication rate is improved.
S106: the base station transmits control information to the RIS.
In one possible implementation, the base station sends control information containing the phase offset matrix and the RIS orientation angle to the controller of the RIS over a backhaul link.
S107: the RIS adjusts the RIS orientation and the phase of each reflective element of the RIS under the control of the control information.
In one possible implementation, after the RIS controller receives the control information, the RIS controller sets the reflection parameters to control each reflection unit to complete the phase adjustment, and controls the motor module to complete the RIS orientation configuration.
Each reflection unit of the RIS is composed of passive device capacitor, resistor and the like, and each reflection unit can reflect signals independently. When there are many reflective units on the RIS and the distance between the reflective units is much smaller than the signal transmission distance, the intelligent reflective surface can be idealized as a continuous surface, i.e. any point on the intelligent reflective surface can reflect a signal.
After the RIS adjusts the orientation and the phase of each reflection unit, the passive beam forming of each target terminal can be completed, and data can be transmitted to the target terminal. Meanwhile, the base station can also transmit data for each target terminal through the direct connection channel. In the method, the target terminal and the base station can communicate through the direct connection channel and the link channel generated by the RIS, so that the problems of channel attenuation and the like between the target terminal and the base station can be solved.
In the RIS control method provided by the embodiment of the application, the base station can acquire the communication requirement information of at least one target terminal in real time, determine the RIS orientation angle based on the communication requirement information of the target terminal and the RIS channel state information, and generate a control signal to control the RIS to adjust the orientation angle. It can be understood that, in the process of communicating with at least one target terminal, the base station acquires the RIS channel state information and the communication requirement information of the target terminal in real time, and adjusts the RIS direction in real time based on the information, so as to meet the real-time requirement of the at least one target terminal, so that the method has higher flexibility.
The foregoing description of the solution provided by the embodiments of the present application has been mainly presented in terms of a method. To achieve the above functions, it includes corresponding hardware structures and/or software modules that perform the respective functions. Those of skill in the art will readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. The technical aim may be to use different methods to implement the described functions for each particular application, but such implementation should not be considered beyond the scope of the present application.
The embodiment of the application also provides a RIS control device 200. Fig. 6 is a schematic structural diagram of an RIS control device 200 according to an embodiment of the present application.
Wherein, RIS control device 200 comprises: an obtaining unit 201, configured to obtain communication requirement information of at least one target terminal; the target terminal is any one of at least one terminal which uses signals transmitted by the base station and has shielding or attenuation with a direct connection channel of the base station; the communication demand information of the target terminal comprises the minimum communication rate of the target terminal; a generating unit 202, configured to generate control information based on the communication requirement information and the RIS channel state information of at least one target terminal; wherein the control information includes an RIS orientation angle; the control information is used for indicating the RIS to adjust the RIS direction based on the RIS direction angle; the RIS orientation angle is related to the beam forming vector of the target terminal, the minimum communication rate of the target terminal, the signal-to-interference ratio of the target terminal and the maximum transmission power of the base station; the beam forming vector of the target terminal, the signal to interference ratio of the target terminal are related to RIS channel state information, the minimum communication rate of the target terminal and the maximum transmission power of the base station; a transmitting unit 203 for transmitting the control information to the RIS. For example, in connection with fig. 3, the acquisition unit 201 is applied to S104 in the method embodiment, the generation unit 202 is applied to S105 in the method embodiment, and the transmission unit 203 is applied to S106 in the method embodiment.
Optionally, the sending unit 203 is further configured to send, before obtaining the communication requirement information of the target terminal, an open instruction to the RIS when it is determined that there is a blocking or attenuation of a direct connection channel between at least one terminal and the base station; wherein the open indication is used to indicate RIS open. With reference to fig. 3, the transmitting unit 203 is applied to S102 in the method embodiment.
Optionally, RIS is oriented at an angle θ 0 Beamforming vector w of kth target terminal with target terminal k Minimum communication rate R of kth target terminal of target terminals k，min Signal-to-interference ratio gamma of kth target terminal of target terminals k And maximum transmission of base stationPower transmission P max The following calculation formula is satisfied: wherein P is 0 Is an objective function; k represents the number of target terminals, K represents the kth target terminal; the RIS comprises a plurality of reflecting units, u m Is the phase offset of the mth reflection unit of the plurality of reflection units of the RIS; />And representing a preset RIS orientation angle regulation range.
Optionally, the RIS channel state information includes: RIS to target terminal channel information r k And base station to RIS channel information G; beamforming vector w of target terminal k Signal-to-interference ratio gamma with target terminal k The following calculation formula is satisfied:
wherein PL is k (θ 0 ) Indicating that the kth target terminal is at theta 0 Loss on path, Φ represents the phase shift matrix, r k And represents channel information of the RIS to the kth target terminal.
Optionally, a preset RIS orientation angle θ 0 Regulatory region of (2)Satisfy->Or satisfy->A discrete adjustable angle set preset in a range; wherein θ AoA，1 Is the angle of the incident wave from the base station to the RIS, θ AoD，2 Is the angle of the outgoing wave from the RIS to the target terminal.
Optionally, the control information further includes: a phase shift matrix; the control information is also used to instruct the RIS to adjust the phase of each reflective element of the RIS based on the phase offset matrix.
Optionally, the phase shift matrix Φ includes a phase shift for each reflective element of the RIS; the phase offset of each reflection unit satisfies the following formula: wherein B represents the number of bits and m represents the mth reflection unit.
Optionally, the solution method of the objective function includes continuous convex approximation and iterative solution.
Of course, the RIS control device 200 provided in the embodiment of the present application includes, but is not limited to, the above modules.
FIG. 7 is a schematic diagram of a RIS control device 300 according to an embodiment of the present application. As shown in fig. 7, the RIS control apparatus 300 includes a processor 301, a memory 302 and a network interface 303.
Wherein the processor 301 comprises one or more CPUs. The CPU may be a single-core CPU (single-CPU) or a multi-core CPU (multi-CPU).
Memory 302 includes, but is not limited to, random access memory (random access memory, RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical memory, or the like.
Optionally, the processor 301 implements the RIS control method provided by the embodiment of the present application by reading the instruction stored in the memory 302, or the processor 301 implements the RIS control method provided by the embodiment of the present application by an instruction stored internally. In the case where the processor 301 implements the method in the above embodiment by reading the instructions stored in the memory 302, the instructions for implementing the RIS control method provided in the embodiment of the present application are stored in the memory 302.
The network interface 303, a type of device that includes a transmitter and a receiver for communicating with other devices or communication networks, may be a wired interface (port), such as a fiber optic distributed data interface (fiber distributed data interface, FDDI), gigabit ethernet interface (GE). Alternatively, the network interface 303 is a wireless interface. It should be appreciated that the network interface 303 includes a plurality of physical ports, the network interface 303 being used for communication and the like.
Optionally, the RIS control device further comprises a bus 304, where the above mentioned processor 301, memory 302, network interface 303 are typically interconnected by means of the bus 304 or otherwise.
In actual implementation, the acquisition unit 201, the generation unit 202, and the transmission unit 203 may be implemented by a processor invoking computer program code in a memory. For specific implementation, reference may be made to the description of the above method section, and details are not repeated here.
The application also provides a RIS control device, which comprises a memory and a processor. The memory is coupled to the processor; the memory is used to store computer program code, which includes computer instructions. Wherein the processor, when executing the computer instructions, causes the RIS control apparatus to perform the steps of the RIS control method shown in the method embodiments described above.
Another embodiment of the present application further provides a computer readable storage medium, where computer instructions are stored, where the computer instructions, when executed on an RIS control device, cause the RIS control device to execute each step executed by the RIS control device in the flow of the RIS control method shown in the foregoing method embodiment.
Another embodiment of the present application also provides a chip system, which is applied to the RIS control device. The system-on-chip includes one or more interface circuits, and one or more processors. The interface circuit and the processor are interconnected by a wire. The interface circuit is configured to receive signals from the memory of the RIS control device and to send signals to the processor, the signals including computer instructions stored in the memory. When the RIS control device processor executes the computer instructions, the RIS control device executes the steps executed by the RIS control device in the RIS control method flow shown in the method embodiment.
In another embodiment of the present application, there is also provided a computer program product including computer instructions that, when executed on an RIS control apparatus, cause the RIS control apparatus to perform the steps performed by the RIS control apparatus in the flow of the RIS control method shown in the foregoing method embodiment.
The above-described embodiments may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, the embodiments described above may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer-executable instructions are loaded and executed on a computer, the processes or functions in accordance with embodiments of the present application are fully or partially produced. The computer may be a general purpose computer, a special purpose computer, a computer network, a server, or other programmable apparatus. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another, for example, a website, computer, server, or data center via a wired (e.g., coaxial cable, fiber optic, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. Computer readable storage media can be any available media that can be accessed by a computer or data storage devices including one or more servers, data centers, etc. that can be integrated with the media. Usable media may be magnetic media (e.g., floppy disks, hard disks, magnetic tape), optical media (e.g., DVD), or semiconductor media (e.g., solid State Disk (SSD)), etc.
The foregoing is only a specific embodiment of the present application. Variations and alternatives will occur to those skilled in the art based on the detailed description provided herein and are intended to be included within the scope of the application.

Claims (10)

1. An intelligent subsurface RIS control method, characterized by being applied to a base station, the base station being connected with an RIS, the method comprising:
acquiring communication demand information of at least one target terminal; the target terminal is any one of at least one terminal which uses signals transmitted by the base station and has shielding or attenuation with a direct connection channel of the base station; the communication demand information of the target terminal comprises the minimum communication rate of the target terminal;
generating control information based on the communication demand information and RIS channel state information of the at least one target terminal; wherein the control information includes an RIS orientation angle; the control information is used for indicating the RIS to adjust the orientation of the RIS based on the RIS orientation angle; the RIS orientation angle is related to a beamforming vector of the target terminal, a minimum communication rate of the target terminal, a signal-to-interference ratio of the target terminal and a maximum transmission power of the base station; the beamforming vector of the target terminal, the signal to interference ratio of the target terminal are related to the RIS channel state information, the minimum communication rate of the target terminal and the maximum transmission power of the base station;
and sending the control information to the RIS.
2. The method according to claim 1, wherein prior to the acquiring the communication requirement information of the target terminal, the method further comprises:
when it is determined that at least one terminal has shielding or attenuation to a direct connection channel of the base station, sending an opening instruction to the RIS; wherein the open indication is used to indicate that the RIS is open.
3. The method of claim 1, wherein theRIS orientation angle θ 0 Beamforming vector w of kth target terminal with the target terminal k Minimum communication rate R of kth target terminal of said target terminals k，min Signal-to-interference ratio gamma of kth target terminal of said target terminals k And the maximum transmission power P of the base station max The following calculation formula is satisfied:
wherein the P is 0 Is an objective function; the K represents the number of the target terminals, and the K represents the kth target terminal; the RIS comprises a plurality of reflection units, the u m Is a phase offset of an mth reflection unit of the plurality of reflection units of the RIS; the saidAnd representing a preset RIS orientation angle regulation range.
4. The method of claim 3, wherein the RIS channel state information comprises: the RIS arrives at the premisesChannel information r of the target terminal k And channel information G of the base station to the RIS; beamforming vector w of the target terminal k And the signal-to-interference ratio gamma of the target terminal k The following calculation formula is satisfied:
wherein the PL is k (θ 0 ) Indicating that the kth target terminal is at theta 0 Loss on path, Φ represents the phase shift matrix, r k And the channel information from the RIS to the kth target terminal is represented.
5. A method according to claim 3 or 4, wherein the predetermined RIS is oriented at an angle θ 0 Regulatory region of (2)Satisfy->Or satisfy->A discrete adjustable angle set preset in a range; wherein said θ AoA，1 Is the angle of the incident wave of the base station to the RIS, said +.>Is the maximum angle of the outgoing wave from the RIS to the kth target terminal.
6. The method of claim 1, wherein the control information further comprises: a phase shift matrix; the control information is also used to instruct the RIS to adjust the phase of each reflective element of the RIS based on the phase offset matrix.
7. The method of claim 6, wherein the phase shift matrix Φ includes a phase shift for each reflective element of the RIS; the phase offset of each reflection unit satisfies the following formula:
wherein B represents the number of bits and m represents the mth reflection unit.
8. A method according to claim 3, wherein the solution method of the objective function comprises a continuous convex approximation and an iterative solution method.
9. A RIS control device comprising a memory and a processor; the memory is coupled to the processor; the memory is used for storing computer program codes, and the computer program codes comprise computer instructions; wherein the computer instructions, when executed by the processor, cause the RIS control apparatus to perform the RIS control method of any one of claims 1 to 8.
10. A computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions; wherein the computer instructions, when run on a RIS control apparatus, cause the RIS control apparatus to perform the RIS control method as claimed in any one of claims 1 to 8.
CN202310820626.6A 2023-07-05 2023-07-05 RIS control method, RIS control device and storage medium Pending CN116722899A (en)

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