Multiple satellite collaborative downlink communication method and system based on intelligent metasurface

Abstract

The present invention provides a method and system for downlink communication of multiple satellites based on intelligent metasurface, the method comprising the following steps: setting multiple satellites to serve ground nodes at the same time to build a direct link between the satellite and the ground node; deploying an intelligent metasurface and building an auxiliary link from the satellite to the intelligent metasurface; based on the collaboration of the direct link and the auxiliary link, downlink communication from the multiple satellites to the ground node is realized. The method and system for downlink communication of multiple satellites based on intelligent metasurface of the present invention uses the intelligent metasurface as a relay to realize downlink communication of multiple satellites, effectively improving the transmission performance of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a method and system for collaborative downlink communications among multiple satellites based on an intelligent metasurface. Background Art

[0002] The three-dimensional network integrating air, space, land and sea is an important vision of the next generation of mobile communication technology. The existing ground cellular network only covers 10% of the earth's surface. Scenarios such as signal coverage in remote areas and communication recovery after natural disasters face difficulties in network deployment. Satellite communications can be used as a supplement to ground cellular networks with its advantages of wide coverage and stable on-orbit status. Therefore, satellite-ground fusion and complementarity are the key to building an air-space-ground-integrated network. Collaborative downlink transmission of multiple satellites can improve the effective service time of the system and increase the system throughput per unit time. The research on key technologies of satellite-ground fusion is the key to building an air-space-ground-integrated network and achieving wide-area signal coverage and seamless service flow.

[0003] However, due to the communication distance of more than hundreds of kilometers, satellite communications face serious path loss; due to the limited on-board resources and transmission power, the cost of deploying large-scale multiple-input multiple-output (MIMO) technology is high, which makes the service quality assurance of satellite-to-ground communications face serious challenges. Summary of the invention

[0004] In view of the shortcomings of the prior art mentioned above, the purpose of the present invention is to provide a method and system for collaborative downlink communication of multiple satellites based on an intelligent metasurface, which uses the intelligent metasurface as a relay to realize collaborative downlink communication of multiple satellites, thereby effectively improving the system transmission performance.

[0005] In a first aspect, the present invention provides a method for collaborative downlink communication of multiple satellites based on an intelligent metasurface, the method comprising the following steps: setting up multiple satellites to serve ground nodes simultaneously to build a direct link between the satellite and the ground node; deploying an intelligent metasurface, and building an auxiliary link from the satellite to the intelligent metasurface; and realizing downlink communication from the multiple satellites to the ground node based on the collaboration of the direct link and the auxiliary link.

[0006] In an implementation manner of the first aspect, the smart metasurface is deployed near the ground node.

[0007] In an implementation manner of the first aspect, the working mode of the smart metasurface is a reflection mode, a transmission mode, or a simultaneous transmission and reflection mode; and the auxiliary link is a reflection link and / or a transmission link.

[0008] In an implementation manner of the first aspect, implementing downlink communications from the multiple satellites to the ground node based on the collaboration of the direct link and the auxiliary link includes the following steps:

[0009] Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information;

[0010] Selecting the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link;

[0011] The signal of the optimized auxiliary link and the signal of the direct link where other satellites are located are phase-aligned at the ground node and then coherently superimposed.

[0012] In an implementation manner of the first aspect, the parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

[0013] In a second aspect, the present invention provides a multiple satellite collaborative downlink communication system based on an intelligent metasurface, the system comprising:

[0014] A plurality of satellites are used to simultaneously serve ground nodes to establish direct links between the satellites and the ground nodes;

[0015] The intelligent metasurface is used to construct an auxiliary link from the satellite to the intelligent metasurface, so that the direct link and the auxiliary link cooperate to realize downlink communication from the multiple satellites to the ground node.

[0016] In an implementation of the second aspect, the smart metasurface is deployed near the ground node.

[0017] In an implementation manner of the second aspect, the working mode of the smart metasurface is a reflection mode, a transmission module or a simultaneous transmission and reflection mode; and the auxiliary link is a reflection link and / or a transmission link.

[0018] In an implementation of the second aspect, the direct link and the auxiliary link cooperate to implement downlink communication from the multiple satellites to the ground node, including the following steps:

[0019] Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information;

[0020] Based on the ground node, select the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link;

[0021] Based on the ground node, the signal of the optimized auxiliary link and the signal of the direct link where other satellites are located are phase-aligned at the ground node and then coherently superimposed.

[0022] In an implementation manner of the second aspect, the parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

[0023] As described above, the method and system for collaborative downlink communication of multiple satellites based on intelligent metasurface of the present invention have the following beneficial effects:

[0024] (1) Introducing smart metasurfaces to assist the downlink transmission of multiple satellites. On the one hand, smart metasurfaces can be flexibly deployed near ground nodes with the advantage of low cost. On the other hand, smart metasurfaces achieve a breakthrough in system performance at the cost of low power consumption, increase the amount of data transmitted during the service cycle, and comply with the development concept of green communications.

[0025] (2) Adaptively optimize the phase of the smart metasurface according to the satellite orbit parameters and operating status, so that the smart metasurface can operate in three modes: reflection, transmission, and simultaneous transmission and reflection;

[0026] (3) The intelligent metasurface can be flexibly deployed near ground receiving nodes. The ground nodes can select the number of satellites for collaborative transmission based on performance indicators such as service demand time and transmission data volume, thereby reducing the number of inter-satellite handovers and significantly increasing the data transmission volume.

[0027] (4) Using smart metasurfaces as relays to improve the transmission rate of collaborative downlink transmissions of multiple satellites. Compared with other active relay methods such as amplification and forwarding and decoding and forwarding technologies, the relay of incident signals by smart metasurfaces does not introduce noise, and does not require a radio frequency link and only achieves passive signal relay with low power consumption;

[0028] (5) It is suitable for solving the problem of limited satellite-to-ground downlink transmission rate due to severe path loss in satellite-to-ground communication scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Shown is a flow chart of a method for collaborative downlink communication of multiple satellites based on a smart metasurface in one embodiment of the present invention;

[0030] Figure 2 Shown is a schematic diagram of a framework of a method for collaborative downlink communication of multiple satellites based on a smart metasurface in one embodiment of the present invention;

[0031] Figure 3 A schematic diagram showing the comparison of the transmission data volume achieved by satellite-to-ground transmission systems assisted by different intelligent metasurfaces in the present invention as a function of service time in one embodiment;

[0032] Figure 4 Shown is a schematic structural diagram of a multiple satellite collaborative downlink communication system based on a smart metasurface in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0035] The method and system for collaborative downlink communication of multiple satellites based on intelligent metasurface of the present invention uses intelligent metasurface as a relay to realize collaborative downlink communication of multiple satellites, effectively increasing the amount of transmitted data within the service cycle. It is suitable for solving the problem of limited satellite-to-ground downlink transmission rate due to severe path loss in satellite-to-ground communication scenarios, and is thus extremely practical.

[0036] Reconfigurable Intelligent Surface (RIS) is developed based on metamaterials and is composed of a large number of low-cost, low-power electromagnetic elements. According to the operation mode of the incident electromagnetic wave, the intelligent metasurface can be divided into reflection type, transmission type and simultaneous reflection and transmission type. By controlling the electromagnetic array elements of the intelligent metasurface, the electromagnetic parameters such as the amplitude and phase of the incident electromagnetic wave can be intelligently adjusted, which can realize the intelligent reconstruction of wireless propagation and build an intelligent radio environment. Since the intelligent metasurface is quasi-passive and does not perform any complex signal processing on the incident electromagnetic wave, it can achieve ideal system performance at a low hardware cost and power consumption, and can be applied to typical scenarios such as blind area coverage, cell edge interference suppression, and coverage enhancement of cellular networks. Introducing the intelligent metasurface into satellite-to-ground communication to establish a reflection link (assuming that the intelligent metasurface works in the reflection mode), on the one hand, it can enhance the signal power at the receiving end through passive beamforming, and on the other hand, it can ensure the continuity of service when the direct link is blocked, thereby improving the robustness of the system. In addition, the reflection link constructed by the intelligent metasurface can ensure the continuity of service when the satellite-to-ground direct link is blocked, thereby improving the robustness of the system. At the same time, due to the high-speed movement of satellites relative to ground users, the service time of single-satellite access is short and the achievable data throughput is low. Considering the collaborative transmission of multiple satellites to meet the high data volume requirements of ground terminals.

[0037] like Figure 1 As shown, in one embodiment, the method for downlink communication of multiple satellites based on intelligent metasurface of the present invention comprises the following steps:

[0038] Step S1, setting a plurality of satellites to serve a ground node simultaneously, so as to construct a direct link between the satellite and the ground node.

[0039] Specifically, at least two low-orbit satellites located in the same orbital plane can perform information transmission and time synchronization through inter-satellite links, and the ground node is stationary and located within the coverage of multiple satellites. A connection can be established when the elevation angle between the satellite and the ground node reaches a critical angle, and the service cycle starts when multiple satellites simultaneously establish a connection with the ground node. Considering the critical elevation angle for establishing a connection between the satellite and the ground node, the effective service time of the collaborative transmission of multiple satellites can be calculated according to the number of satellites for collaborative transmission and related satellite orbit parameters. Considering that the transmission power of multiple satellites is the same, the direct link serves the ground node in a joint processing collaborative multi-point transmission manner. The multi-channel signals from multiple satellites are coherently superimposed after phase alignment at the ground node to realize the downlink transmission of information. The collaborative transmission of multiple satellites greatly improves the achievable transmission rate of the system when the resources of a single satellite are limited; at the same time, when a single satellite moves at high speed relative to the ground, it ensures continuous service while reducing the number of inter-satellite switching times for ground nodes to access the satellite network.

[0040] Step S2: deploy an intelligent metasurface and construct an auxiliary link from the satellite to the intelligent metasurface.

[0041] Specifically, the smart metasurface is developed from metamaterial technology. It is regarded as one of the key enabling technologies for the next generation of mobile communications with its low cost, low power consumption, easy deployment and programmable performance advantages. It can reconstruct the electromagnetic propagation environment through intelligent regulation of electromagnetic units. Therefore, the smart metasurface acts as a relay and can realize signal relay between the satellite and the ground node. Among them, the link between the satellite and the smart metasurface is called an auxiliary link. Considering the smart metasurface working in the reflection mode, by intelligently regulating the phase amplitude parameters of the reflection array elements of the smart metasurface, the coherent superposition of the reflected signals at the receiving end can be achieved, which greatly improves the receiving signal-to-noise ratio at the receiving end and improves the transmission rate of the system.

[0042] Considering the multiplicative attenuation of the reflective link caused by the introduction of the smart metasurface, the deployment position of the smart metasurface should be as close to the transmitter or receiver as possible. At the same time, a sufficient number of smart metasurface array elements are required to provide sufficient multipath to compensate for signal transmission loss. Preferably, considering the limited resources on the satellite and the adjustment of physical parameters such as the pitch angle of the smart metasurface, the smart metasurface is deployed close to the ground node to ensure service quality.

[0043] In one embodiment, the working mode of the smart metasurface can be a reflection mode, a transmission mode, or a simultaneous transmission and reflection mode. Therefore, the auxiliary link is a reflection link and / or a transmission link.

[0044] Step S3: realizing downlink communication from the multiple satellites to the ground node based on the collaboration of the direct link and the auxiliary link.

[0045] Specifically, considering the different positions of multiple satellites, after the multiple direct link signals of multiple satellites and ground nodes are phase-aligned, the reflection phase design of the smart metasurface cannot simultaneously meet the phase alignment of multiple reflection links and direct links. Therefore, by considering the distance factor that mainly affects the path loss and the symmetry of the orbits of multiple satellites, the service cycle of multiple satellites and ground nodes is divided into multiple stages, and the phase optimization target of the smart metasurface is the auxiliary link corresponding to the satellite closest to the ground node in each stage.

[0046] In one embodiment, implementing downlink communication from the plurality of satellites to the ground node based on the collaboration of the direct link and the auxiliary link includes the following steps:

[0047] 31) Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information. The parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

[0048] Among them, based on the known access satellite orbit parameters and predictable operating status, the ground node transmits control information to the intelligent metasurface through wired or wireless means and synchronizes it in real time. The intelligent metasurface adjusts parameters according to the control information, thereby ensuring that the intelligent metasurface is in the optimal pitch angle posture, and realizing passive beamforming by real-time control of the reflection / transmission coefficient of the intelligent metasurface, thereby improving the strength of the received signal.

[0049] 32) Selecting the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link.

[0050] Considering the distance factor that plays a decisive role in path loss, the phase optimization of the smart metasurface can be divided into multiple stages within the continuous service time according to the communication distance between multiple satellites and ground nodes. In each stage, the satellite closest to the ground node is selected as the target of reflection link phase optimization based on the known satellite orbit state, that is, the signal with the highest intensity in the reflection link is selected to achieve phase alignment with other direct link signals at the ground node for coherent superposition, thereby maximizing the ground node receiving power within the overall service time.

[0051] 33) Phase-aligning the signal of the optimized auxiliary link and the signal of the direct link where other satellites are located at the ground node and then coherently superimposing them.

[0052] The protection scope of the method for collaborative downlink communication of multiple satellites based on intelligent metasurface described in the embodiment of the present invention is not limited to the execution order of the steps listed in this embodiment. All solutions implemented by adding, reducing or replacing steps in the prior art based on the principles of the present invention are included in the protection scope of the present invention.

[0053] The following is a specific example to further illustrate the method for collaborative downlink communication of multiple satellites based on an intelligent metasurface of the present invention.

[0054] like Figure 2 As shown in the figure, consider two satellites for cooperative transmission, namely satellite 1 and satellite 2. Point O is the center of the earth, and A and B are the subsatellite points of satellites 1 and 2 respectively. Considering the orbits of satellites 1 and 2, satellites 1 and 2 form a fixed angle α with the center of the earth. β represents the elevation angle between the satellite and the ground node. The intelligent reflector is deployed near the ground node to assist the satellite-to-ground communication in the reflection working mode. Figure 3 As shown, by simulating and comparing the transmission data volume that can be achieved by satellite-to-ground transmission systems assisted by different intelligent reflectors, the present invention divides the phase optimization of the intelligent reflector into two stages, corresponding to the optimization of the reflection links of satellite 1 and satellite 2, respectively, which can achieve the maximum data transmission volume within the service time. Compared with the dual-satellite system without the assistance of intelligent reflectors, the improvement of system performance is mainly related to factors such as the number of elements of the intelligent reflector array, the deployment position and deployment posture of the intelligent reflector. The method of the present invention can be extended from the cooperative downlink transmission of dual satellites to the cooperative downlink transmission of N satellites, and the phase optimization of the corresponding intelligent reflector is adaptively divided into N stages.

[0055] An embodiment of the present invention also provides a multiple satellite collaborative downlink communication system based on an intelligent metasurface, and the multiple satellite collaborative downlink communication system based on an intelligent metasurface can implement the multiple satellite collaborative downlink communication method based on an intelligent metasurface described in the present invention, but the implementation device of the multiple satellite collaborative downlink communication system based on an intelligent metasurface described in the present invention includes but is not limited to the structure of the multiple satellite collaborative downlink communication system based on an intelligent metasurface listed in this embodiment. All structural deformations and replacements of the prior art made according to the principles of the present invention are included in the protection scope of the present invention.

[0056] like Figure 4 As shown, in one embodiment, the multiple satellite cooperative downlink communication system based on the intelligent metasurface of the present invention includes:

[0057] A plurality of satellites 41 are used to simultaneously serve ground nodes to establish direct links between the satellites and the ground nodes.

[0058] Specifically, at least two low-orbit satellites located in the same orbital plane can perform information transmission and time synchronization through inter-satellite links, and the ground node is stationary and located within the coverage of multiple satellites. A connection can be established when the elevation angle between the satellite and the ground node reaches a critical angle, and the service cycle starts when multiple satellites simultaneously establish a connection with the ground node. Considering the critical elevation angle for establishing a connection between the satellite and the ground node, the effective service time of the collaborative transmission of multiple satellites can be calculated according to the number of satellites for collaborative transmission and related satellite orbit parameters. Considering that the transmission power of multiple satellites is the same, the direct link serves the ground node in a joint processing collaborative multi-point transmission manner. The multi-channel signals from multiple satellites are coherently superimposed after phase alignment at the ground node to realize the downlink transmission of information. The collaborative transmission of multiple satellites greatly improves the achievable transmission rate of the system when the resources of a single satellite are limited; at the same time, when a single satellite moves at high speed relative to the ground, it ensures continuous service while reducing the number of inter-satellite switching times for ground nodes to access the satellite network.

[0059] The intelligent metasurface 42 is used to construct an auxiliary link from the satellite to the intelligent metasurface, so that the direct link and the auxiliary link cooperate to realize downlink communication from the multiple satellites to the ground node.

[0060] Specifically, the smart metasurface is developed from metamaterial technology. It is regarded as one of the key enabling technologies for the next generation of mobile communications with its low cost, low power consumption, easy deployment and programmable performance advantages. It can reconstruct the electromagnetic propagation environment through intelligent regulation of electromagnetic units. Therefore, the smart metasurface acts as a relay and can realize signal relay between the satellite and the ground node. Among them, the link between the satellite and the smart metasurface is called an auxiliary link. Considering the smart metasurface working in the reflection mode, by intelligently regulating the phase amplitude parameters of the reflection array elements of the smart metasurface, the coherent superposition of the reflected signals at the receiving end can be achieved, which greatly improves the receiving signal-to-noise ratio at the receiving end and improves the transmission rate of the system.

[0061] Considering the multiplicative attenuation of the reflective link caused by the introduction of the smart metasurface, the deployment position of the smart metasurface should be as close to the transmitter or receiver as possible. At the same time, a sufficient number of smart metasurface array elements are required to provide sufficient multipath to compensate for signal transmission loss. Preferably, considering the limited resources on the satellite and the adjustment of physical parameters such as the pitch angle of the smart metasurface, the smart metasurface is deployed close to the ground node to ensure service quality.

[0062] In one embodiment, the working mode of the smart metasurface can be a reflection mode, a transmission mode, or a simultaneous transmission and reflection mode. Therefore, the auxiliary link is a reflection link and / or a transmission link.

[0063] Considering the different positions of multiple satellites, after the multiple direct link signals between multiple satellites and ground nodes are phase-aligned, the reflection phase design of the smart metasurface cannot simultaneously meet the phase alignment of multiple reflection links and direct links. Therefore, by considering the distance factor that mainly affects the path loss and the symmetry of the orbits of multiple satellites, the service cycle of multiple satellites and ground nodes is divided into multiple stages. The phase optimization target of the smart metasurface is the auxiliary link corresponding to the satellite closest to the ground node in each stage.

[0064] In one embodiment, implementing downlink communication from the plurality of satellites to the ground node based on the collaboration of the direct link and the auxiliary link includes the following steps:

[0065] 31) Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information. The parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

[0066] Among them, based on the known access satellite orbit parameters and predictable operating status, the ground node transmits control information to the intelligent metasurface through wired or wireless means and synchronizes it in real time. The intelligent metasurface adjusts parameters according to the control information, thereby ensuring that the intelligent metasurface is in the optimal pitch angle posture, and realizing passive beamforming by real-time control of the reflection / transmission coefficient of the intelligent metasurface, thereby improving the strength of the received signal.

[0067] 32) Based on the ground node, select the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link.

[0068] Considering the distance factor that plays a decisive role in path loss, the phase optimization of the smart metasurface can be divided into multiple stages within the continuous service time according to the communication distance between multiple satellites and ground nodes. In each stage, the satellite closest to the ground node is selected as the target of reflection link phase optimization based on the known satellite orbit state, that is, the signal with the highest intensity in the reflection link is selected to achieve phase alignment with other direct link signals at the ground node for coherent superposition, thereby maximizing the ground node receiving power within the overall service time.

[0069] 33) Based on the ground node, the signal of the optimized auxiliary link and the signal of the direct link where other satellites are located are phase-aligned at the ground node and then coherently superimposed.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A collaborative downlink communication method for multiple satellites based on intelligent metasurfaces. Features: The method comprises the following steps: Arrange a plurality of satellites to serve a ground node simultaneously, so as to establish a direct link between the satellite and the ground node; deploying a smart metasurface and constructing an auxiliary link from the satellite to the smart metasurface; Implementing downlink communication from the multiple satellites to the ground node based on the collaboration of the direct link and the auxiliary link; Implementing downlink communication from the plurality of satellites to the ground node based on the coordination of the direct link and the auxiliary link comprises the following steps: Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information; Selecting the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link; Phase-aligning the signal of the optimized auxiliary link and the signal of the direct link where other satellites are located at the ground node and then coherently superimposing them; The working mode of the smart metasurface is a reflection mode, a transmission module or a simultaneous transmission and reflection mode; the auxiliary link is a reflection link and / or a transmission link; The service cycles of multiple satellites and ground nodes are divided into multiple stages. The auxiliary link corresponding to the satellite closest to the ground node in each stage is selected to achieve phase alignment with other direct link signals at the ground node for coherent superposition.

2. According to claim 1, the method for collaborative downlink communication of multiple satellites based on intelligent metasurface, Features: The smart metasurface is deployed near the ground node.

3. The method for collaborative downlink communication of multiple satellites based on smart metasurface according to claim 1, Features: The parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

4. A multi-satellite collaborative downlink communication system based on intelligent metasurface, Features: The system comprises: A plurality of satellites are used to simultaneously serve ground nodes to establish direct links between the satellites and the ground nodes; An intelligent metasurface, used to construct an auxiliary link from the satellite to the intelligent metasurface, so that the direct link and the auxiliary link cooperate to realize downlink communication from the multiple satellites to the ground node; The direct link and the auxiliary link cooperate to realize downlink communication from the multiple satellites to the ground node, comprising the following steps: Based on the ground node providing control information to the smart metasurface, the smart metasurface adjusts parameters according to the control information; Selecting the auxiliary link where the satellite closest to the ground node is located as the optimized auxiliary link; Phase-aligning the signal of the optimized auxiliary link and the signal of the direct link where other satellites are located at the ground node and then coherently superimposing them; The working mode of the smart metasurface is a reflection mode, a transmission module or a simultaneous transmission and reflection mode; the auxiliary link is a reflection link and / or a transmission link; The service cycles of multiple satellites and ground nodes are divided into multiple stages. The auxiliary link corresponding to the satellite closest to the ground node in each stage is selected to achieve phase alignment with other direct link signals at the ground node for coherent superposition.

5. According to claim 4, the multiple satellite cooperative downlink communication system based on the intelligent metasurface, Features: The smart metasurface is deployed near the ground node.

6. According to claim 4, the multiple satellite cooperative downlink communication system based on the intelligent metasurface, Features: The parameters include array element phase amplitude parameters and pitch angle parameters of the smart metasurface.

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