Wireless communication transmission method and system based on active-passive hybrid intelligent metasurface

Abstract

The embodiment of the present application provides a wireless communication transmission method and system based on an active-passive hybrid intelligent metasurface, which belongs to the field of wireless communication technology. The method includes: each terminal sends uplink pilot information to a base station and each active-passive hybrid intelligent metasurface; each active-passive hybrid intelligent metasurface selects an active antenna unit to receive the uplink pilot information; the base station uses a channel estimation algorithm to obtain all uplink channel information; each active-passive hybrid intelligent metasurface is set; the terminal sends an uplink signal; the base station jointly processes all received uplink signals based on its uplink channel information and the uplink channel information of the active antenna unit; the base station jointly encodes the downlink pilot information or downlink data according to the target criterion and the uplink channel information of the base station, and jointly sends it through the antenna array of the base station and the active antenna units of each active-passive hybrid intelligent metasurface; and the transmission performance is improved based on the active-passive hybrid intelligent metasurface.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a wireless communication transmission method and system based on an active-passive hybrid intelligent metasurface. Background Art

[0002] At present, with the rapid changes in science and technology and the development trend of society towards the Internet of Everything, mobile communication systems have evolved to the fifth generation (5G) with mobile Internet and Internet of Things services as the main goals. With the continuous development of mobile communications, mobile communication technology benefits all aspects of human life. In order to meet the business needs of various scenarios, massive input and output (Multiple In Multiple Out, MIMO) technology deploys large-scale antenna arrays at base stations to serve multiple user terminals at the same time, making full use of the high spatial resolution and rich spatial freedom brought by large-scale antenna arrays, effectively improving the spectrum efficiency of the system, and thus being widely studied and commercially applied as one of the key technologies of 5G.

[0003] The successful large-scale commercial use of 5G has promoted the research and thinking of the industry and academia on the next generation of mobile communications (6G). In particular, in order to achieve the goal of 6G from the Internet of Everything to the Intelligent Internet of Everything, in addition to exploring new wireless air interface technologies, it is also necessary to further enhance and upgrade existing air interface technologies such as large-scale MIMO technology to meet and support the business needs of future 6G networks. On the other hand, thanks to its excellent low power consumption and easy deployment characteristics, smart metasurfaces can be widely deployed in daily environments, effectively solving problems such as signal coverage blind spots, and have also received widespread attention from industry and academia in recent years. Smart metasurfaces are also called Reconfigurable Intelligent Surface (RIS), Intelligent Reflecting Surface (IRS), Large Intelligent Surface (LIS), etc., and are all expressed as RIS in this application.

[0004] The RIS architecture currently used is mostly a fully passive architecture, that is, a large number of programmable passive reflective antenna units are constructed using sub-wavelength two-dimensional metamaterials and PIN tubes, and the incident electromagnetic waves are regulated and reflected based on digital coding, thereby providing the communication system with the ability to reshape the signal propagation environment and adding an additional degree of freedom in channel design to the communication system design. By optimizing the reflection coefficient of RIS, many theories and experiments on RIS have verified its great value in solving communication problems such as blind area coverage and channel environment deterioration, and can effectively improve the energy efficiency and spectrum efficiency of existing communication systems.

[0005] However, the existing fully passive RIS architecture still has many bottleneck problems. For example, many theoretical studies and experimental results have proved that in order to obtain sufficient beamforming gain to help the existing communication system achieve better signal area coverage and transmission rate improvement, it is usually necessary to configure a large number of antenna units on the fully passive RIS side. However, effective beamforming requires accurate acquisition of channel state information on the RIS side, and the deployment of a large number of antenna units poses a severe challenge to the acquisition of channel state information for RIS-assisted communication systems.

[0006] In fact, the pilot overhead required by the existing RIS cascade channel state information estimation algorithm based on pilot signals generally increases linearly with the increase in the number of antenna units on the RIS side. When a large number of antenna units are configured on the RIS side, the acquisition of channel state information on the RIS side will greatly increase the computational complexity and signal processing delay of the system, thereby limiting the application potential of RIS. In addition, although the performance of existing communication systems can be improved by optimizing the reflection coefficient of RIS to achieve waveform shaping, there are still many theoretical studies that prove that under the condition of a given total transmission power, compared with the forward decoding relay communication system, RIS requires at least several hundred antenna units to provide equivalent performance gain to the forward decoding relay communication system.

[0007] To this end, a variety of different RIS architectures have been proposed to further improve the performance of RIS-assisted systems. For example, the semi-passive RIS architecture replaces a small number of passive reflective antenna units with antenna units with signal receiving capabilities and adds a simple signal processing module to achieve the reception of pilot signals and channel estimation on the RIS side during the pilot training phase, thereby obtaining accurate channel state information on the RIS side. Compared with the fully passive RIS architecture, this passive RIS architecture can effectively reduce the pilot training overhead while effectively improving the beamforming capability of RIS. The relay-reflection hybrid RIS architecture improves system performance by further replacing a small number of passive reflective antenna units on the fully passive RIS architecture with relay module units with signal amplification capabilities.

[0008] Unfortunately, the performance gain that the above RIS architecture can bring to the communication system is still relatively limited. The reason is that the transmitted signal is reflected (or amplified) by the RIS and then reaches the receiving end, passing through the cascade channel constructed by each RIS antenna unit. Therefore, its channel gain is the product of the two cascade channel gains, and the equivalent channel gain is small, so that only by adjusting the phase, number and signal amplification power of the passive reflection antenna unit and the relay module unit on the RIS, it is still impossible to meet the higher data transmission requirements. In addition, although the reflection coefficient of RIS is currently dynamically adjustable, the RIS architecture still lacks environmental adaptability. In order to cope with the diverse communication needs in the future, the RIS architecture should also be reconfigurable, and the architecture can be adjusted according to different environments or channel states to achieve its maximum gain. Summary of the invention

[0009] In order to solve the above technical problems, the embodiments of the present application provide a wireless communication transmission method and system based on an active-passive hybrid intelligent metasurface.

[0010] In a first aspect, an embodiment of the present application provides a wireless communication transmission method based on an active-passive hybrid intelligent metasurface, which is applied to a wireless communication transmission system based on an active-passive hybrid intelligent metasurface, wherein the system includes a base station, K terminals and M active-passive hybrid intelligent metasurfaces, wherein each active-passive hybrid intelligent metasurface is composed of a passive reflection antenna unit, a control module and a passive-to-active unit circuit that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after programming and enabling; the number and position of the active antenna unit are respectively determined by the number and position of the enabled passive-to-active unit circuit; the base station is respectively connected to the control module and the active antenna unit of each active-passive hybrid intelligent metasurface through an optical fiber or a radio frequency cable, and the method includes:

[0011] Uplink pilot training stage: each terminal sends uplink pilot information to the base station and each active-passive hybrid intelligent metasurface respectively; each active-passive hybrid intelligent metasurface enables part of the passive-to-active unit circuit to select part of the passive reflection antenna unit as the active antenna unit according to the selection criteria to receive the uplink pilot information, and transmits the received uplink pilot information to the base station through the cable; the base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by each active-passive hybrid intelligent metasurface through the cable, and uses the channel estimation algorithm to obtain all uplink channel information; the control module of each active-passive hybrid intelligent metasurface enables the passive-to-active unit circuit of each active-passive hybrid intelligent metasurface and sets the reflection coefficient of the passive reflection antenna unit according to the uplink channel information and the target criteria;

[0012] Uplink data transmission stage: the terminal sends uplink signals to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; the base station receives the corresponding uplink signal through its own antenna; the active antenna unit of each of the active and passive hybrid intelligent metasurfaces transmits the received uplink signal to the base station; the base station jointly processes all received uplink signals based on the uplink channel information of the base station obtained in the uplink pilot training stage and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces;

[0013] Downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

[0014] In a second aspect, an embodiment of the present application provides a wireless communication transmission system based on an active-passive hybrid intelligent metasurface, the system comprising a base station, K terminals and M active-passive hybrid intelligent metasurfaces: each active-passive hybrid intelligent metasurface is composed of a passive reflection antenna unit, a control module and a passive-to-active unit circuit that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after programming and enabling; the number and position of the active antenna unit are respectively determined by the number and position of the enabled passive-to-active unit circuit; the base station is respectively connected to the control module and the active antenna unit of each active-passive hybrid intelligent metasurface through an optical fiber or a radio frequency cable;

[0015] Uplink pilot training stage: the terminal sends uplink pilot information to the base station and each of the active-passive hybrid intelligent metasurfaces respectively; each of the active-passive hybrid intelligent metasurfaces enables part of the passive-to-active unit circuit to select part of the passive reflection antenna unit as the active antenna unit according to the selection criteria to receive the uplink pilot information, and transmits the received uplink pilot information to the base station through a cable; the base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by each of the active-passive hybrid intelligent metasurfaces through the cable, and uses a channel estimation algorithm to obtain all uplink channel information; the control module of each of the active-passive hybrid intelligent metasurfaces enables the passive-to-active unit circuit of each of the active-passive hybrid intelligent metasurfaces and sets the reflection coefficient of the passive reflection antenna unit according to the uplink channel information and the target criteria;

[0016] Uplink data transmission stage: the terminal sends uplink signals to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; the base station receives the corresponding uplink signal through its own antenna; the active antenna unit of each of the active and passive hybrid intelligent metasurfaces transmits the received uplink signal to the base station; the base station jointly processes all received uplink signals based on the uplink channel information of the base station obtained in the uplink pilot training stage and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces;

[0017] Downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

[0018] The wireless communication transmission method and system based on the active-passive hybrid intelligent metasurface provided in the present application can dynamically enable the passive-to-active unit circuit of the active-passive hybrid intelligent metasurface according to different environments and transmission requirements, and adjust the architecture of the intelligent metasurface and the reflection coefficient of the reflection antenna unit in real time, effectively solving the problems of low equivalent channel gain of the existing RIS architecture and difficulty in obtaining accurate channel state information on the RIS side; it can fully combine the advantages of existing wireless communication systems and intelligent metasurfaces, and utilize the design freedom of architecture and reflection coefficient brought by active-passive hybrid intelligent metasurfaces to solve the problems of traditional communication systems in blind area coverage, channel environment deterioration, etc., thereby giving full play to the performance gain brought by distributed active-passive hybrid intelligent metasurfaces and greatly enhancing the transmission performance of existing wireless communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope of protection of the present application. In each of the drawings, similar components are numbered similarly.

[0020] Figure 1 A schematic structural diagram of a wireless communication transmission system based on an active-passive hybrid intelligent metasurface provided in an embodiment of the present application is shown;

[0021] Figure 2 A schematic diagram of a process of a wireless communication transmission method based on an active-passive hybrid intelligent metasurface provided in an embodiment of the present application is shown;

[0022] Figure 3Another flow chart of the wireless communication transmission method based on the active-passive hybrid intelligent metasurface provided in an embodiment of the present application is shown.

[0023] Main icons: 100-base station; 200-active and passive hybrid intelligent metasurface; 201-control module; 202-active antenna unit; 203-passive reflection antenna unit; 300-terminal. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0025] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0026] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present application, are intended only to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing items or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing items.

[0027] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0028] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0029] Example 1

[0030] An embodiment of the present application provides a wireless communication transmission method based on an active-passive hybrid intelligent metasurface. The method is applied to a wireless communication transmission system based on an active-passive hybrid intelligent metasurface to fully utilize the low-cost deployment and flexible signal coverage enhancement advantages of the intelligent metasurface to further improve the uplink and downlink data transmission performance of the wireless communication transmission system.

[0031] See also Figure 1 The wireless communication transmission system based on active-passive hybrid intelligent metasurface includes a base station 100, K terminals 300 and multiple active-passive hybrid intelligent metasurfaces 200, and the M active-passive hybrid intelligent metasurfaces 200 can be distributedly deployed around the base station or the terminal. Each active-passive hybrid intelligent metasurface 200 is composed of a passive reflection antenna unit 203, a control module 201 and a passive-to-active unit circuit (not shown) that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after programming and enabling; the number and position of the active antenna unit are respectively determined by the number and position of the enabled passive-to-active unit circuit; the base station is connected to the control module and active antenna unit of each active-passive hybrid intelligent metasurface through optical fiber or radio frequency cable.

[0032] The number of antennas of the base station 100 may be N, and the terminal 300 may use a single antenna or multiple antennas. Each active-passive hybrid intelligent metasurface 200 is composed of a passive reflection antenna unit 203, a control module 201, and a passive-to-active unit circuit (not shown) that can be customized and enabled; after being programmed and enabled, the passive-to-active unit circuit can convert the passive reflection antenna unit 203 at the location into an active antenna unit, such as Figure 1 The active antenna unit 202 in the system is connected to a radio frequency link to realize the functions of receiving and transmitting radio frequency signals, up and down frequency conversion, and analog-to-digital / digital-to-analog conversion; the number and position of the active antenna unit 202 are determined by the number and position of the enabled passive-to-active unit circuits. The base station is connected to the control modules 201 and active antenna units 202 of M active-passive hybrid intelligent metasurfaces 200 through optical fibers or radio frequency cables, respectively, to realize the reflection phase control of the passive reflection antenna units 203 of all active-passive hybrid intelligent metasurfaces 200 and the signal reception and transmission of the active antenna unit 202.

[0033] Exemplarily, the number of passive reflection antenna unit circuits of the i-th active-passive hybrid smart metasurface 200 is A i , the number of passive-to-active unit circuits enabled by the i-th active-passive hybrid intelligent metasurface is B i , where 1≤i≤M, and i is an integer. B i <<A iThe position of the specifically enabled passive-to-active unit circuit can be quickly configured through programming, and the passive reflection antenna unit connected to the enabled passive-to-active unit circuit serves as the active antenna unit.

[0034] Combine the following Figures 1 to 3 The wireless communication transmission method based on the active-passive hybrid intelligent metasurface provided in this embodiment is described.

[0035] See also Figure 2 , the wireless communication transmission method based on active-passive hybrid intelligent metasurface includes:

[0036] Step S201, uplink pilot training phase: each of the terminals sends uplink pilot information to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; each of the active and passive hybrid intelligent metasurfaces enables part of the passive-to-active unit circuit to select part of the passive reflection antenna unit as the active antenna unit according to the selection criteria to receive the uplink pilot information, and transmits the received uplink pilot information to the base station through a cable; the base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by each of the active and passive hybrid intelligent metasurfaces through the cable, and uses a channel estimation algorithm to obtain all uplink channel information; the control module of each of the active and passive hybrid intelligent metasurfaces enables the passive-to-active unit circuit of each of the active and passive hybrid intelligent metasurfaces and sets the reflection coefficient of the passive reflection antenna unit according to the uplink channel information and the target criteria.

[0037] In this embodiment, each of the active-passive hybrid intelligent metasurfaces includes a plurality of the passive reflection antenna units, each of the passive reflection antenna units is correspondingly configured with one passive-to-active unit circuit, and the number of passive-to-active unit circuits enabled by each of the active-passive hybrid intelligent metasurfaces is less than or equal to the number of passive-to-active unit circuits of each of the active-passive hybrid intelligent metasurfaces.

[0038] Demonstration, in Figure 1 In the example, the number of passive reflection antenna unit circuits of the i-th active-passive hybrid intelligent metasurface is A. i , correspondingly, the passive reflection antenna unit of the i-th active-passive hybrid intelligent metasurface is also A i , a passive reflection antenna unit circuit corresponds to a passive reflection antenna unit.

[0039] In this embodiment, the selection criterion is any one of the following: random selection, equal interval selection, minimum uplink channel information completion error of multiple passive reflection antenna units of each active and passive hybrid intelligent metasurface, or the combination of the base station and the active antenna units of each active and passive hybrid intelligent metasurface can achieve maximum uplink reception rate.

[0040] Exemplarily, some passive-to-active unit circuits may be randomly selected and enabled.

[0041] In one embodiment, the base station jointly estimates the uplink channel information of the base station and the uplink channel information of all units of each active and passive hybrid intelligent metasurface based on the uplink pilot information received by its own antenna and the uplink pilot information transmitted by each active and passive hybrid intelligent metasurface; or

[0042] The base station estimates the uplink channel information of the base station according to the uplink pilot information received by its own antenna, estimates the uplink channel information of the active antenna units of each active-passive hybrid intelligent metasurface, and obtains the uplink channel information of all units of each active-passive hybrid intelligent metasurface by using a matrix completion algorithm;

[0043] Among them, all units of each active-passive hybrid intelligent metasurface include active antenna units and passive antenna units of each active-passive hybrid intelligent metasurface.

[0044] In one embodiment, in the uplink pilot training phase, the target criterion is: maximizing the achievable data transmission rate of the signal sent by the terminal to reach the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths; or,

[0045] The signal-to-noise ratio of the signal sent by the terminal reaching the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths is maximized.

[0046] Demonstration, combined Figure 1 , taking the i-th active-passive hybrid intelligent metasurface 200 assisting the k-th terminal 300 in uplink channel estimation as an example:

[0047] When the kth terminal 300 sends uplink pilot information to the base station 100 and each active-passive hybrid intelligent metasurface 200, the uplink pilot information y received by the base station 100's own antenna and the uplink pilot information u received by the active antenna unit of each active-passive hybrid intelligent metasurface 200 are i The received signal models are expressed by the following formulas:

[0048]

[0049]

[0050] Among them, h UB，k is the uplink channel between the kth terminal 300 and the base station 100, h UI，kis the uplink channel between the kth terminal 300 and the ith active-passive hybrid intelligent metasurface 200, H IB，i is the uplink channel between the i-th active-passive hybrid intelligent metasurface 200 and the base station 100. k is the equivalent uplink channel between the terminal 300 and the base station 100, g k is the uplink channel between the terminal 300 and the active antenna unit of the active-passive hybrid intelligent metasurface 200. I is a diagonal matrix, n BS With A i n I,i are the signal receiving noise vectors of the base station and the i-th active-passive hybrid intelligent metasurface active antenna unit. i The active antenna unit indicator matrix and V i is the reflection coefficient vector of the passive reflection antenna unit.

[0051] Specifically, A i For (A i +B i )*(A i +B i )-dimensional diagonal matrix, A i (j, j) = 1 means that the jth element of the i-th active-passive hybrid intelligent metasurface 200 is an active antenna unit (with a maximum of B i ), A i (j, j) = 0 means that the jth element of the i-th active-passive hybrid intelligent metasurface is a passive reflection unit (with a total of A i -B i V i =[v i，1 , v i，2 , …, v i，M ] is the reflection coefficient vector, which can be adjusted according to different requirements. For example, the mth element is where θ m is the adjustable phase of the mth unit (the type of the mth unit is indicated by the unit indicator matrix A i For example, when the mth unit is in a passive reflection state, that is, A i (m, m) = 0), |α i | is the adjustable amplitude of the mth unit. diag(·) is the operator that converts the vector into a diagonal matrix. k is the signal transmission power of the kth terminal 300, x k is the information symbol sent by the kth terminal 300. BS is the signal receiving noise vector of the base station, A i n I，iis the signal reception noise vector of the i-th active-passive hybrid smart metasurface active antenna unit.

[0052] In this embodiment, each channel is represented by a parameterized channel model as follows:

[0053]

[0054]

[0055]

[0056] In the channel model, is the complex gain of the lth path between the kth terminal 300 and the base station 100, is the complex gain of the lth path between the kth terminal 300 and the i-th active-passive hybrid intelligent metasurface 200, is the complex gain of the lth path between the i-th active-passive hybrid intelligent metasurface 200 and the base station 100. UB，k is the number of paths between the kth terminal 300 and the base station 100, L UI，k is the number of paths between the kth terminal 300 and the i-th active-passive hybrid intelligent metasurface 200, L IB，i is the number of paths between the i-th active-passive hybrid intelligent metasurface 200 and the base station channel. θ and ψ represent the arrival angle and transmission angle of the path according to different subscripts, respectively. a(·) is the array response vector determined by the topology of the uplink receiving antenna array (base station antenna and active antenna unit of the active-passive hybrid intelligent metasurface), and its form is as follows:

[0057]

[0058] Where λ is the system carrier wavelength, a i ∈{1,2,…,N a} is the receiving antenna index (N a is the number of antennas, for example, for the array response vector of the base station, N a =N; for the array response vector of the active-passive hybrid intelligent metasurface, N a =B i ), d is the antenna spacing (determined by the antenna array topology).

[0059] In one embodiment, if the terminal 300 sends a total of T pilot signals, the T received signal vectors are arranged in a matrix to obtain uplink pilot received signal matrices Y and U. i as follows:

[0060] Y=[y1,y2,…,y T ]

[0061] U i=[u i，1 ,u i，2 ,…,u i，T ]

[0062] Finally, uplink channel estimation can be modeled as the following parameter estimation problem:

[0063]

[0064] Among them, {α, θ, ψ} are the channel parameters to be estimated (the channel path subscript is omitted), σ BS is the base station receiving signal noise, σ I The active antenna unit of the active-passive hybrid intelligent metasurface receives signal noise, c and d are hyperparameters related to noise, and F(·) is the constraint function of the parameters {α, θ, ψ}. This constraint function uses the prior knowledge of parameters to limit the variable dimension of the parameter space according to different channel characteristics, thereby reducing the computational complexity of parameter estimation.

[0065] Under different environments and channel characteristics, the above problems can be solved by a variety of methods. For example, when the active antenna unit of the active-passive hybrid intelligent metasurface receives a low signal noise intensity, the uplink channel g between the equivalent terminal and the active-passive hybrid intelligent metasurface active antenna unit is k It can be solved by least squares As shown below:

[0066]

[0067] Among them, P k is the average power of the uplink pilot signal sent by the kth user, is a pseudo inverse matrix that arranges the T pilot signal vectors in a matrix.

[0068] Using the above estimated Get h UI，k Then, the pilot signal received at the base station is used to jointly estimate the remaining channel parameters using algorithms such as, but not limited to, matrix completion, and finally recover h UB，k With H IB，i .

[0069] The above-mentioned uplink pilot training phase solution is only a preferred implementation of the present invention, and there may be other implementations, which are not limited here.

[0070] Step S202, uplink data transmission stage: the terminal sends uplink signals to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; the base station receives the corresponding uplink signal through its own antenna; the active antenna unit of each of the active and passive hybrid intelligent metasurfaces transmits the received uplink signal to the base station; the base station jointly processes all received uplink signals based on the uplink channel information of the base station obtained in the uplink pilot training stage and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

[0071] In one embodiment, during the uplink data transmission phase, the uplink signal received by the base station using its own antenna includes at least one of the following: a signal transmitted via a line-of-sight path, a signal reflected by each of the active and passive hybrid intelligent metasurfaces, and a signal reflected by other scatterers in the environment;

[0072] The uplink signal received by the base station includes: the uplink signal received by the base station's own antenna and the uplink signal transmitted to the base station by the active antenna units of each of the active-passive hybrid intelligent metasurfaces through the cable.

[0073] Demonstration, combined Figure 1 , an example is given in which the i-th active-passive hybrid intelligent metasurface 200 assists the k-th terminal 300 in uplink signal transmission and uplink and downlink channel conversion in the time division duplexing (TDD) mode.

[0074] When the terminal 300 sends data to the base station 100 and the active-passive hybrid intelligent metasurface 200, the signal received by the base station 100's own antenna receiving the terminal 300 and the signal received by the active antenna unit of the i-th active-passive hybrid intelligent metasurface 200 can be represented by the following model:

[0075]

[0076]

[0077] Among them, s k is the uplink transmission data symbol of the kth terminal 300, y s is the signal received by the base station’s own antenna, u i，s is the signal received by the active antenna unit of the i-th active-passive hybrid intelligent metasurface 200, h k With g k is an equivalent channel.

[0078] Based on the above two received signals, different signal recovery methods can be selected according to the actual hardware architecture design and transmission environment characteristics, using but not limited to, maximum ratio combining receiver (Maximum Ratio Combining, MRC), zero forcing receiver (Zero Forcing Combining, ZF), minimum mean square error receiver (Minimum Mean Square Error Combining, MMSE) and other low-complexity linear signal processing receivers or other nonlinear signal processing receivers to recover the uplink transmission data.

[0079] In this embodiment, a Maximum Ratio Combining (MRC) receiver is taken as an example:

[0080] First, the received signal is expressed in the following equivalent form:

[0081]

[0082] where h k With g k h k =h UB，k +H IB，i (IA i )diag(v i )h UI g k =A i h UI，k , h and n are respectively k With g k , n BS With A i n I，i The arranged block equivalent channel vector and equivalent receiving noise vector are defined as follows:

[0083]

[0084] Then the received signal after MRC has the following representation:

[0085]

[0086] Due to the reciprocity of the TDD system, it can be seen that the uplink channel and the downlink channel have the following relationship:

[0087]

[0088]

[0089]

[0090] in and is the uplink channel estimated in step 201, and It is a downlink channel obtained by utilizing the channel reciprocity in the TDD system.

[0091] Step S203, downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

[0092] In one implementation, during the downlink transmission phase, the base station adopts a joint precoding criterion of: maximizing the signal to interference and noise ratio of the terminal; or maximizing the downlink transmission rate of the system.

[0093] In this embodiment, combined with Figure 1 , taking the i-th active-passive hybrid intelligent metasurface 200 assisting the base station 100 in transmitting data to K terminals 300 as an example, the following description is made:

[0094] When the base station 100 performs joint transmission to K terminals 300, the received signal of the kth terminal 300 can be represented by the following model:

[0095] y k =A k +B k +C k +D k +n k

[0096] Among them, A k , B k , C k , and D k The corresponding relations are as follows:

[0097]

[0098]

[0099]

[0100]

[0101] in, and are the transmit beamforming vectors of the base station and the active antenna unit of the active-passive hybrid smart metasurface, n kThe noise of the signal received by the kth terminal, n o The interference noise caused by the active antenna unit of the active-passive hybrid smart metasurface, P k is the transmission power of the base station to the kth terminal signal, Q k is the transmission power of the active antenna unit of the active-passive hybrid intelligent metasurface to the kth terminal signal, t k is the transmission data symbol for the kth terminal. Then, according to different target criteria, the passive unit reflection coefficient, the active and passive unit indicator matrix and the transmit beamforming vector are designed to maximize the system performance.

[0102] See also Figure 3 The wireless communication transmission method based on the active-passive hybrid intelligent metasurface provided in this embodiment further includes the following steps:

[0103] Step S200, synchronization and access stage: the base station broadcasts a synchronization sequence to each of the terminals; each of the terminals uses the received synchronization sequence to complete synchronization with the base station and initiates an uplink access request to complete the initial access of each of the terminals; the base station synchronizes with each of the active and passive hybrid intelligent metasurfaces through the cable based on the network clock synchronization protocol; and the initialization of each of the active and passive hybrid intelligent metasurfaces is controlled by a control module of each of the active and passive hybrid intelligent metasurfaces.

[0104] In one embodiment, during the synchronization and access stage, the initialization of each of the active-passive hybrid intelligent metasurfaces includes the initialization of the enable settings of each of the passive-to-active unit circuits and the initialization of the reflection coefficient settings of the passive reflection antenna units.

[0105] It should be additionally explained that the steps S200, S201, S202 and S203 may be performed in sequence.

[0106] The wireless communication transmission method based on the active-passive hybrid intelligent metasurface provided in this embodiment can dynamically enable the passive-to-active unit circuit of the active and passive hybrid intelligent metasurface according to different environments and transmission requirements, and adjust the architecture of the intelligent metasurface and the reflection coefficient of the reflection antenna unit in real time, effectively solving the problems of low equivalent channel gain of the existing RIS architecture and difficulty in obtaining accurate channel state information on the RIS side; it can fully combine the advantages of the existing wireless communication system and the intelligent metasurface, and utilize the design freedom of the architecture and reflection coefficient brought by the active-passive hybrid intelligent metasurface to solve the problems of the traditional communication system in blind area coverage, channel environment deterioration, etc., so as to give full play to the performance gain brought by the distributed active-passive hybrid intelligent metasurface and greatly enhance the transmission performance of the existing wireless communication.

[0107] Example 2

[0108] In addition, an embodiment of the present application provides a wireless communication transmission system based on an active-passive hybrid intelligent metasurface, including a base station, K terminals and M active-passive hybrid intelligent metasurfaces: each of the active-passive hybrid intelligent metasurfaces is composed of a passive reflection antenna unit, a control module and a passive-to-active unit circuit that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after programming and enabling; the number and position of the active antenna unit are respectively determined by the number and position of the enabled passive-to-active unit circuit; the base station is respectively connected to the control module and the active antenna unit of each active-passive hybrid intelligent metasurface through an optical fiber or a radio frequency cable,

[0109] Uplink pilot training stage: the terminal sends uplink pilot information to the base station and each of the active-passive hybrid intelligent metasurfaces respectively; each of the active-passive hybrid intelligent metasurfaces enables part of the passive-to-active unit circuit to select part of the passive reflection antenna unit as the active antenna unit according to the selection criteria to receive the uplink pilot information, and transmits the received uplink pilot information to the base station through a cable; the base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by each of the active-passive hybrid intelligent metasurfaces through the cable, and uses a channel estimation algorithm to obtain all uplink channel information; the control module of each of the active-passive hybrid intelligent metasurfaces enables the passive-to-active unit circuit of each of the active-passive hybrid intelligent metasurfaces and sets the reflection coefficient of the passive reflection antenna unit according to the uplink channel information and the target criteria;

[0110] Uplink data transmission stage: the terminal sends uplink signals to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; the base station receives the corresponding uplink signal through its own antenna; the active antenna unit of each of the active and passive hybrid intelligent metasurfaces transmits the received uplink signal to the base station; the base station jointly processes all received uplink signals based on the uplink channel information of the base station obtained in the uplink pilot training stage and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces;

[0111] Downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

[0112] In one embodiment, in the synchronization and access stage: the base station broadcasts a synchronization sequence to each of the terminals; each of the terminals uses the received synchronization sequence to complete synchronization with the base station and initiates an uplink access request to complete the initial access of each of the terminals; the base station synchronizes with each of the active and passive hybrid intelligent metasurfaces through the cable based on the network clock synchronization protocol; and the initialization of each of the active and passive hybrid intelligent metasurfaces is controlled by a control module of each of the active and passive hybrid intelligent metasurfaces.

[0113] In one embodiment, during the synchronization and access stage, the initialization of each of the active-passive hybrid intelligent metasurfaces includes the initialization of the enable settings of each of the passive-to-active unit circuits and the initialization of the reflection coefficient settings of the passive reflection antenna units.

[0114] In one embodiment, each of the active-passive hybrid intelligent metasurfaces includes a plurality of the passive reflection antenna units, each of the passive reflection antenna units is correspondingly configured with one passive-to-active unit circuit, and the number of passive-to-active unit circuits enabled by each of the active-passive hybrid intelligent metasurfaces is less than or equal to the number of passive-to-active unit circuits of each of the active-passive hybrid intelligent metasurfaces.

[0115] In one embodiment, the selection criterion is any one of the following: random selection, equally spaced selection, minimum uplink channel information completion error of multiple passive reflection antenna units of each active-passive hybrid intelligent metasurface, or the combination of the base station and the active antenna units of each active-passive hybrid intelligent metasurface can achieve maximum uplink reception rate.

[0116] In one implementation, the adopting a channel estimation algorithm to obtain all uplink channel information includes:

[0117] The base station jointly estimates the uplink channel information of the base station and the uplink channel information of all units of each active and passive hybrid intelligent metasurface based on the uplink pilot information received by its own antenna and the uplink pilot information transmitted by each active and passive hybrid intelligent metasurface; or

[0118] The base station estimates the uplink channel information of the base station according to the uplink pilot information received by its own antenna, estimates the uplink channel information of the active antenna units of each active-passive hybrid intelligent metasurface, and obtains the uplink channel information of all units of each active-passive hybrid intelligent metasurface by using a matrix completion algorithm;

[0119] Among them, all units of each active-passive hybrid intelligent metasurface include active antenna units and passive antenna units of each active-passive hybrid intelligent metasurface.

[0120] In one embodiment, in the uplink pilot training phase, the target criterion is: maximizing the achievable data transmission rate of the signal sent by the terminal to reach the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths; or,

[0121] The signal-to-noise ratio of the signal sent by the terminal reaching the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths is maximized.

[0122] In one embodiment, during the uplink data transmission phase, the uplink signal received by the base station using its own antenna includes at least one of the following: a signal transmitted via a line-of-sight path, a signal reflected by each of the active and passive hybrid intelligent metasurfaces, and a signal reflected by other scatterers in the environment;

[0123] The uplink signal received by the base station includes: the uplink signal received by the base station's own antenna and the uplink signal transmitted to the base station by the active antenna unit of each active-passive hybrid intelligent metasurface through the cable;

[0124] In one implementation, during the downlink transmission phase, the base station adopts a joint precoding criterion of: maximizing the signal to interference and noise ratio of the terminal; or maximizing the downlink transmission rate of the system.

[0125] The wireless communication transmission system based on the active-passive hybrid intelligent metasurface provided in this embodiment can implement the wireless communication transmission method based on the active-passive hybrid intelligent metasurface provided in Example 1. To avoid repetition, it will not be repeated here.

[0126] The wireless communication transmission system based on the active-passive hybrid intelligent metasurface provided in this embodiment can dynamically enable the passive-to-active unit circuit of the active and passive hybrid intelligent metasurface according to different environments and transmission requirements, and adjust the architecture of the intelligent metasurface and the reflection coefficient of the reflection antenna unit in real time, effectively solving the problems of low equivalent channel gain of the existing RIS architecture and difficulty in obtaining accurate channel state information on the RIS side; it can fully combine the advantages of the existing wireless communication system and the intelligent metasurface, and utilize the design freedom of the architecture and reflection coefficient brought by the active-passive hybrid intelligent metasurface to solve the problems of the traditional communication system in blind area coverage, channel environment deterioration, etc., thereby giving full play to the performance gain brought by the distributed active-passive hybrid intelligent metasurface and greatly enhancing the transmission performance of the existing wireless communication.

[0127] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or terminal including the element.

[0128] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for a computer device to execute the methods described in each embodiment of the present application.

[0129] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A wireless communication transmission method based on active-passive hybrid intelligent metasurface, characterized in that: Applied to a wireless communication transmission system based on an active-passive hybrid intelligent metasurface, the system includes a base station, K terminals and M active-passive hybrid intelligent metasurfaces, each of which is composed of a passive reflection antenna unit, a control module and a passive-to-active unit circuit that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after being programmed and enabled; The number and position of the active antenna units are determined by the number and position of the enabled passive-to-active unit circuits respectively; The base station is connected to the control module and active antenna unit of each active-passive hybrid intelligent metasurface respectively through optical fiber or radio frequency cable, and the method includes: Uplink pilot training stage: each terminal sends uplink pilot information to the base station and each active-passive hybrid intelligent metasurface respectively; each active-passive hybrid intelligent metasurface enables part of the passive-to-active unit circuit to select part of the passive reflection antenna unit as the active antenna unit according to the selection criteria to receive the uplink pilot information, and transmits the received uplink pilot information to the base station through the cable; the base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by each active-passive hybrid intelligent metasurface through the cable, and uses the channel estimation algorithm to obtain all uplink channel information; the control module of each active-passive hybrid intelligent metasurface enables the passive-to-active unit circuit of each active-passive hybrid intelligent metasurface and sets the reflection coefficient of the passive reflection antenna unit according to the uplink channel information and the target criteria; Uplink data transmission stage: the terminal sends uplink signals to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; the base station receives the corresponding uplink signal through its own antenna; the active antenna unit of each of the active and passive hybrid intelligent metasurfaces transmits the received uplink signal to the base station; the base station jointly processes all received uplink signals based on the uplink channel information of the base station obtained in the uplink pilot training stage and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces; Downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

2. The method according to claim 1, characterized in that Before the uplink pilot training phase, the method further includes: Synchronization and access stage: the base station broadcasts a synchronization sequence to each of the terminals; each of the terminals uses the received synchronization sequence to complete synchronization with the base station and initiates an uplink access request to complete the initial access of each of the terminals; the base station synchronizes with each of the active and passive hybrid intelligent metasurfaces through the cable based on the network clock synchronization protocol; the initialization of each of the active and passive hybrid intelligent metasurfaces is controlled by the control module of each of the active and passive hybrid intelligent metasurfaces.

3. The method according to claim 2, characterized in that In the synchronization and access stage, the initialization of each active-passive hybrid intelligent metasurface includes the initialization of the enable setting of each passive-to-active unit circuit and the initialization of the reflection coefficient setting of the passive reflection antenna unit.

4. The method according to claim 1, characterized in that: Each of the active-passive hybrid intelligent metasurfaces includes a plurality of the passive reflection antenna units, each of the passive reflection antenna units is correspondingly configured with one passive-to-active unit circuit, and the number of passive-to-active unit circuits enabled by each of the active-passive hybrid intelligent metasurfaces is less than or equal to the number of passive-to-active unit circuits of each of the active-passive hybrid intelligent metasurfaces.

5. The method according to claim 1, characterized in that The selection criteria are any one of the following: random selection, equally spaced selection, the minimum uplink channel information completion error of multiple passive reflection antenna units of each active-passive hybrid intelligent metasurface, or the combination of the base station and the active antenna units of each active-passive hybrid intelligent metasurface can achieve the maximum uplink reception rate.

6. The method according to claim 1, characterized in that The adopting of a channel estimation algorithm to obtain all uplink channel information includes: The base station jointly estimates the uplink channel information of the base station and the uplink channel information of all units of each active and passive hybrid intelligent metasurface based on the uplink pilot information received by its own antenna and the uplink pilot information transmitted by each active and passive hybrid intelligent metasurface; or The base station estimates the uplink channel information of the base station according to the uplink pilot information received by its own antenna, estimates the uplink channel information of the active antenna units of each active-passive hybrid intelligent metasurface, and obtains the uplink channel information of all units of each active-passive hybrid intelligent metasurface by using a matrix completion algorithm; Among them, all units of each active-passive hybrid intelligent metasurface include active antenna units and passive antenna units of each active-passive hybrid intelligent metasurface.

7. The method according to claim 1, characterized in that In the uplink pilot training phase, the target criterion is: to maximize the achievable data transmission rate of the signal sent by the terminal to reach the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths; or, The signal-to-noise ratio of the signal sent by the terminal reaching the base station via the reflection path constructed by each active-passive hybrid intelligent metasurface and other propagation paths is maximized.

8. The method according to claim 1, characterized in that In the uplink data transmission stage, the uplink signal received by the base station using its own antenna includes at least one of the following: a signal transmitted via a line-of-sight path, a signal reflected by each of the active and passive hybrid intelligent metasurfaces, and a signal reflected by other scatterers in the environment; The uplink signal received by the base station includes: the uplink signal received by the base station's own antenna and the uplink signal transmitted to the base station by the active antenna units of each of the active-passive hybrid intelligent metasurfaces through the cable.

9. The method according to claim 1, characterized in that: In the downlink transmission phase, the joint precoding criterion adopted by the base station is: maximizing the signal to interference and noise ratio of the terminal; or maximizing the downlink transmission rate of the system.

10. A wireless communication transmission system based on active-passive hybrid intelligent metasurface, characterized in that: The system includes a base station, K terminals and M active-passive hybrid intelligent metasurfaces: each active-passive hybrid intelligent metasurface is composed of a passive reflection antenna unit, a control module and a passive-to-active unit circuit that can be customized and enabled; the passive-to-active unit circuit can convert the passive reflection antenna unit at the location into an active antenna unit after being programmed and enabled; The number and position of the active antenna units are determined by the number and position of the enabled passive-to-active unit circuits respectively; The base station is connected to the control module and active antenna unit of each active-passive hybrid intelligent metasurface respectively through optical fiber or radio frequency cable; Uplink pilot training stage: the terminal sends uplink pilot information to the base station and each of the active and passive hybrid intelligent metasurfaces respectively; Each of the active-passive hybrid intelligent metasurfaces enables a partial passive-to-active unit circuit to select a partial passive reflective antenna unit as an active antenna unit according to a selection criterion to receive uplink pilot information, and transmits the received uplink pilot information to the base station via a cable; The base station uses its own antenna to receive the uplink pilot information sent by the terminal and the uplink pilot information sent by the terminal received by the active antenna unit transmitted by the active-passive hybrid intelligent metasurface through the cable, and uses a channel estimation algorithm to obtain all uplink channel information; The control module of each active-passive hybrid intelligent metasurface sets the enabling of the passive-to-active unit circuit and the reflection coefficient of the passive reflection antenna unit of each active-passive hybrid intelligent metasurface according to the uplink channel information and the target criterion; Uplink data transmission stage: the terminal sends an uplink signal to the base station and each of the active-passive hybrid intelligent metasurfaces respectively; The base station receives the corresponding uplink signal through its own antenna; The active antenna unit of each active-passive hybrid intelligent metasurface transmits the received uplink signal to the base station; The base station jointly processes all received uplink signals according to the uplink channel information of the base station obtained in the uplink pilot training phase and the uplink channel information of the active antenna units of each active-passive hybrid intelligent metasurface; Downlink transmission phase: the base station jointly encodes the downlink pilot information or downlink data to be sent according to the target criterion, the uplink channel information of the base station obtained in the uplink pilot training phase, and the uplink channel information of the active antenna units of each of the active and passive hybrid intelligent metasurfaces, and jointly sends it through the antenna array of the base station and the active antenna units of each of the active and passive hybrid intelligent metasurfaces.

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