Power control method and device based on reconfigurable holographic metasurface

Abstract

The present invention discloses a communication system power control method and device based on a reconfigurable holographic metasurface, comprising: constructing an optimization problem between a variable to be optimized and a target to be optimized; solving the optimization problem based on constraints to obtain the value of the variable to be optimized; and generating a communication system power control scheme using the value of the variable to be optimized. The present invention improves the communication performance such as the total communication rate and energy efficiency by optimizing the base station transmission power in the reconfigurable holographic metasurface communication system.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and in particular to a method and device for controlling power of a communication system based on a reconfigurable holographic metasurface. Background Art

[0002] At present, with the continuous development of mobile devices and smart terminals, the demand for data traffic in future wireless networks is growing dramatically. In order to meet the rapidly growing demand for data traffic and achieve seamless communication, D2D technology is considered to be a promising solution. In D2D communication, users can communicate directly without forwarding through the base station (BS). Due to the short transmission distance between users, D2D communication can reduce energy consumption, provide early warning in emergency situations, and improve users' QoS (quality of service) requirements. In general, allowing D2D links to share uplink spectrum with cellular links can alleviate the problem of insufficient spectrum. However, shared spectrum will cause D2D links to cause inevitable interference to cellular networks, which will have a serious impact on the communication quality of cellular networks.

[0003] An innovative and revolutionary technology, namely reconstructible holographic metasurface RHS, can effectively eliminate D2D interference and meet the requirements of high data rates. RHS is an ultra-thin planar antenna with many metamaterial radiating elements embedded on the antenna surface. Specifically, the reference wave generated by the antenna feed excites the RHS in the form of surface waves, making it possible to manufacture the RHS with a compact structure based on printed circuit board (PCB) technology. Specifically, the holographic antenna uses metal patches to construct a holographic pattern on the surface, and records the interference between the reference wave and the target wave according to the interference principle. Then, according to the holographic pattern, each radiating element can generate the desired radiation direction by electrically controlling the radiation amplitude of the reference wave. Therefore, compared with traditional dish antennas and phased array antennas, RHS can achieve dynamic beamforming without heavy mechanical motion devices and complex phase shifting circuits, which can greatly save antenna manufacturing costs and power loss. At the same time, its thin and light structure is also very easy to install. Summary of the invention

[0004] In order to solve the problem of lack of power control method in communication system based on reconfigurable holographic metasurface, the present invention provides a power control method and device based on reconfigurable holographic metasurface, which solves the power control problem by modeling the communication system and using optimization method.

[0005] The technical contents of the present invention include:

[0006] A communication system power control method based on a reconfigurable holographic metasurface is applicable to a communication system composed of a base station equipped with a reconfigurable holographic metasurface, and the steps include:

[0007] 1) constructing an optimization problem between variables to be optimized and targets to be optimized, wherein the variables to be optimized include variables related to power control, and the targets to be optimized include maximizing system performance;

[0008] 2) Solve the optimization problem based on the constraints and obtain the value of the variable to be optimized;

[0009] 3) Generate a communication system power control scheme using the values ​​of the variables to be optimized.

[0010] Furthermore, the reconfigurable holographic metasurface includes: N radiation units and K feed sources, wherein each feed source is connected to a radio frequency link of a base station.

[0011] Furthermore, variables related to power control include: the beamforming matrix Ψ of the reconfigurable holographic metasurface and the digital beamforming matrix B of the base station.

[0012] Furthermore, the system performance includes: total transmission rate R or energy efficiency η.

[0013] Furthermore, the constraints include: emission power constraint and reconfigurable holographic metasurface amplitude constraint.

[0014] Furthermore, the transmission power constraint includes: the transmission power of the base station cannot exceed a set upper limit.

[0015] Furthermore, the amplitude constraint of the reconfigurable holographic metasurface includes: the amplitude of the reconfigurable holographic metasurface takes values ​​between [0,1].

[0016] Furthermore, the method for solving the optimization problem includes: an iterative optimization method.

[0017] A storage medium stores a computer program, wherein the computer program is configured to execute the above method when running.

[0018] An electronic device includes a memory and a processor, wherein the memory stores a program for executing the above method.

[0019] Compared with the prior art, the present invention improves communication performance such as total communication rate and energy efficiency by optimizing the base station transmission power in the reconfigurable holographic metasurface communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the reconfigurable holographic metasurface of the present invention.

[0021] Figure 2 It is a schematic diagram of a downlink multi-user wireless communication system.

[0022] Figure 3 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only specific embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The reconfigurable holographic metasurface (RHS) is composed of a feed source, a parallel plate waveguide, and a metamaterial radiation unit array. Figure 1 As shown, the feed source emits an electromagnetic wave, which propagates in the parallel plate waveguide. During the propagation process, the metamaterial radiation unit is controlled by multiple PIN diodes. By adjusting the switching state of the PIN diode corresponding to the metamaterial radiation unit, the finite discrete radiation amplitude of the electromagnetic wave propagating to the metamaterial radiation unit can be adjusted. If there are 1 PIN diodes controlling one metamaterial radiation unit, the unit has 2 I Therefore, the switching state of the PIN diode in the metasurface unit is adjusted to the target switching value, and the amplitude value of the electromagnetic wave radiated on the metamaterial radiation unit is the target discretized amplitude value.

[0025] We consider a downlink multi-user wireless communication system such as Figure 2 As shown. The system includes a base station equipped with RHS and multiple mobile users communicating with the base station in this cell. Assume that the total number of users in this cell is M. RHS has a total of N radiation units and K feed sources. Each feed source is connected to a radio frequency link of the base station.

[0026] The communication system power control method of the present invention is as follows: Figure 3 As shown, the power control optimization problem is first modeled as

[0027]

[0028] stP(v)≤P M ,

[0029]

[0030] Where v refers to the variable to be optimized (including the RHS beamforming matrix Ψ), f(v) refers to the target to be optimized (such as total communication rate, energy efficiency). P(V) is the total power of the base station. M is the upper limit of the total power of the cell base station and RHS. n is the amplitude value of the nth metamaterial radiation unit of RHS; the RHS beamforming matrix Ψ is an N*N matrix, and its element in the nth row and nth column is ψn , all elements outside the diagonal are 0.2 I is the number of adjustable discrete amplitude values. By solving this problem, a power control scheme can be obtained.

[0031] Depending on the application, the variables and functions in the above optimization problem have different forms. For example, assume that the variables to be optimized are the RHS beamforming matrix Ψ and the base station digital beamforming matrix B. When the objective function is the total transmission rate When , the expression can be written as

[0032]

[0033] Among them, H m represents the channel from RHS to user m. Q is the propagation matrix from RHS to the metamaterial radiation unit. m is the mth column of matrix B, representing the digital beamforming vector of the mth user signal. 2 is the noise power. When the objective function is energy efficiency, its expression can be written as

[0034]

[0035] Where R represents the total transmission rate. The total power of the base station and RHS in this cell can be written as

[0036] P(Ψ,B)=P on +tr(|ΨQB| 2 )

[0037] Where P on Refers to the fixed power consumption of the base station.

[0038] These optimization problems can be solved using a variety of optimization algorithms, such as iterative optimization, which will not be described here.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A communication system power control method based on a reconfigurable holographic metasurface, applicable to a communication system composed of a base station equipped with a reconfigurable holographic metasurface, wherein the reconfigurable holographic metasurface comprises: N radiating elements and K feed sources, wherein each feed source is connected to a radio frequency link of a base station; The feed source emits an electromagnetic wave, which propagates in a parallel plate waveguide. During the propagation process, the radiation unit is controlled by a plurality of PIN diodes. By adjusting the switch state of the PIN diode corresponding to the radiation unit, the finite discrete radiation amplitude of the electromagnetic wave propagating to the radiation unit can be adjusted. The switch state of the PIN diode in the metasurface unit is adjusted to a target switch value, and the amplitude value of the electromagnetic wave radiated from the radiation unit is a target discretized amplitude value. The steps include: 1) Construct an optimization problem between variables to be optimized and targets to be optimized, wherein the variables to be optimized include variables related to power control, and the targets to be optimized include maximizing system performance; the variables related to power control include: the beamforming matrix of the reconfigurable holographic metasurface and the digital beamforming matrix of the base station; the system performance includes: total transmission rate or energy efficiency; 2) Solving the optimization problem based on constraint conditions to obtain the value of the variable to be optimized; the constraint conditions include: transmission power constraint and reconfigurable holographic metasurface amplitude constraint; 3) Using the values ​​of the variables to be optimized, generate a communication system power control scheme according to the following formula: Where v represents the variable to be optimized, Ψ represents the RHS beamforming matrix, represents the target to be optimized, Represents the total power of the base station, P M represents the upper limit of the total power of the cell base station and RHS, ψ n represents the amplitude value of the nth metamaterial radiation unit of RHS. The RHS beamforming matrix Ψ is an N*N matrix, and its element in the nth row and nth column is ψ n , all elements outside the diagonal are 0, 2 I is the number of adjustable discrete amplitude values; Assume that the variables to be optimized are the RHS beamforming matrix Ψ and the base station digital beamforming matrix B; When the objective function is the total transmission rate When the expression is max Ψ,B R, where H m represents the channel from RHS to user m, Q is the propagation matrix from the feed source to the metamaterial radiation unit, and b m is the mth column of matrix B, representing the digital beamforming vector of the mth user signal, σ 2 is the noise power; or When the objective function is energy efficiency, its expression is: Where R represents the total transmission rate; the total power of the base station and RHS in this cell can be written as P(Ψ,B)=P on +tr(|ΨQB| 2 ), where P on Refers to the fixed power consumption of the base station.

2. The method according to claim 1, characterized in that Transmit power constraints include: the transmit power of the base station cannot exceed the set upper limit.

3. The method according to claim 1, characterized in that The amplitude constraints of the reconfigurable holographic metasurface include: the amplitude of the reconfigurable holographic metasurface takes values ​​between [0,1].

4. The method according to claim 1, characterized in that Methods for solving optimization problems include: iterative optimization methods.

5. A storage medium storing a computer program, wherein: The computer program is configured to execute the method according to any one of claims 1 to 4 when executed.

6. An electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to perform the method according to any one of claims 1 to 4.

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