阅读说明：本技术 一种波束赋形方法、装置、计算机设备和存储介质 (Beam forming method, device, computer equipment and storage medium ) 是由 张雷 王玉 卜晓煊 王永星 田建杰 尚玉龙 于 2021-05-31 设计创作，主要内容包括：本发明适用无线通信领域,提供波束赋形方法、装置、计算机设备和存储介质,包括：根据从用户发射机到从用户接收机的通道、智能反射面到从用户接收机的反射通道、从用户发射机到智能反射面的通道、智能反射面相移矩阵及主动发射预编码矩阵,确定每个从用户接收机的信噪比；根据通过智能反射面从从用户发射机到主用户接收机的级联信道、从用户发射机到智能反射面的通道及主动发射预编码矩阵,确定施加在主用户接收机的干扰温度；根据信噪比、干扰温度、反射波束形成的单位模量,基于有界信道状态信息误差模型求解最优的主动发射预编码矩阵及最优的智能反射面相移矩阵。本发明可以实现在主从用户间信道状态信息不精确时从用户发送功率的显著降低。(The invention is suitable for the wireless communication field, and provides a beam forming method, a beam forming device, computer equipment and a storage medium, wherein the beam forming method comprises the following steps: determining the signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmission precoding matrix; determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix; and solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio, the interference temperature and the unit modulus formed by the reflected wave beams. The invention can realize the obvious reduction of the slave user transmitting power when the channel state information between the master user and the slave user is not accurate.)

1. A method for beamforming, comprising:

determining a signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmission precoding matrix;

determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix;

and solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

2. The method of claim 1, wherein the step of determining the interference temperature applied to the primary user receiver based on a cascade channel from the user transmitter to the primary user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface, the intelligent reflecting surface phase shift matrix, and the active transmit precoding matrix comprises:

integrating a cascade channel from a user transmitter to a main user receiver and a channel from the user transmitter to the main user receiver through an intelligent reflecting surface into a channel equivalent combination form;

obtaining estimated comprehensive channel state information and a comprehensive channel state information error matrix from a user transmitter according to the channel equivalent combination form and the uncertainty of the channel;

and determining the interference temperature applied to the master user receiver according to the estimated comprehensive channel state information, the comprehensive channel state information error matrix, the intelligent reflecting surface phase shift matrix and the active transmitting pre-coding matrix at the slave user transmitter.

3. The beamforming method according to claim 2, wherein the channel set from the user transmitter to the intelligent reflecting surface through the cascade channel from the user transmitter to the primary user receiver by the intelligent reflecting surface is a channel equivalent combination of:

wherein G is the equivalent combination form of the channels,the expression size is NxM_tThe complex matrix of (a) is then formed,for cascading messages from a subscriber transmitter to a primary subscriber receiver via an intelligent reflecting surfaceRoad, g_r∈C^N×1Is the reflection channel from the intelligent reflecting surface to the primary user receiver,for passage from the user transmitter to the intelligent reflective surface,for the passage from the user transmitter to the main user receiver, M_tThe intelligent reflecting surface consists of N reflecting elements, counted from the antennas of the user transmitter.

4. The method of claim 2, wherein the formula for determining the interference temperature applied to the primary user receiver based on the estimated integrated channel state information, the integrated channel state information error matrix, the intelligent reflector phase shift matrix, and the active transmit precoding matrix at the secondary user transmitter is:

where IT is the interference temperature imposed on the primary user receiver,is the estimated integrated channel state information at ST, deltag is the integrated channel state information error matrix,in order to actively transmit the precoding matrix,Φ＝diag{φ₁,φ₂,...,φ_Nis an intelligent reflecting surface phase shift matrix.

5. The method according to claim 1, wherein the step of solving the optimal active transmit precoding matrix and the optimal intelligent reflection plane phase shift matrix based on the bounded channel state information error model according to the snr of each secondary user receiver, the interference temperature applied to the primary user receiver, the unit modulus of the reflected beam forming comprises:

based on a bounded channel state information error model, randomly presetting an initial active transmitting precoding matrix and an initial intelligent reflecting surface phase shift matrix;

fixing the initial intelligent reflecting surface phase shift matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams, and solving and optimizing an active transmitting precoding matrix;

fixing the initial active transmitting pre-coding matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams, and solving an optimized intelligent reflecting surface phase-shift matrix;

when the current data rate and the data rate under the previous iteration are judged not to meet the error regulation, the optimized active transmitting precoding matrix and the optimized intelligent reflecting surface phase shift matrix are used as a new generation of initial active transmitting precoding matrix and a new generation of intelligent reflecting surface phase shift matrix, and the steps of fixing the initial intelligent reflecting surface phase shift matrix and solving the optimized active transmitting precoding matrix are returned according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams;

and when the current data rate and the data rate under the previous iteration are judged to meet the error regulation, determining the current optimized active transmitting pre-coding matrix and the optimized intelligent reflecting surface phase shift matrix as the optimal active transmitting pre-coding matrix and the optimal intelligent reflecting surface phase shift matrix.

6. A beamforming apparatus, comprising:

the signal-to-noise ratio determining unit is used for determining the signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmitting precoding matrix;

the interference temperature determining unit is used for determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix; and

and the optimal matrix determining unit is used for solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

7. The beamforming apparatus according to claim 6, wherein the interference temperature determining unit comprises:

the channel integration module is used for integrating a cascade channel from a user transmitter to a main user receiver and a channel from the user transmitter to the main user receiver into a channel equivalent combination form through an intelligent reflecting surface;

an error matrix obtaining module, configured to obtain estimated integrated channel state information and an integrated channel state information error matrix from a user transmitter according to the channel equivalent combination form and uncertainty of a channel; and

and the interference temperature determining module is used for determining the interference temperature applied to the master user receiver according to the estimated comprehensive channel state information, the comprehensive channel state information error matrix, the intelligent reflecting surface phase shift matrix and the active transmitting precoding matrix at the slave user transmitter.

8. The beamforming apparatus according to claim 6, wherein the optimal matrix determining unit comprises:

the preset initial matrix module is used for randomly presetting an initial active transmitting precoding matrix and an initial intelligent reflecting surface phase shift matrix based on a bounded channel state information error model;

the optimized active transmitting precoding matrix solving module is used for fixing the initial intelligent reflecting surface phase shift matrix and solving an optimized active transmitting precoding matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams;

the optimized intelligent reflecting surface phase shift matrix solving module is used for fixing the initial active transmitting precoding matrix and solving an optimized intelligent reflecting surface phase shift matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams;

a first judging module, configured to, when it is judged that the current data rate and the data rate under the previous iteration do not satisfy the error specification, take the optimized active transmission precoding matrix and the optimized intelligent reflective surface phase shift matrix as a new-generation initial active transmission precoding matrix and a new-generation intelligent reflective surface phase shift matrix, and return to the step of fixing the initial intelligent reflective surface phase shift matrix and solving the optimized active transmission precoding matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver, and the unit modulus formed by the reflected beams; and

and the second judging module is used for determining the current optimized active transmitting precoding matrix and the optimized intelligent reflecting surface phase shift matrix as the optimal active transmitting precoding matrix and the optimal intelligent reflecting surface phase shift matrix when judging that the current data rate and the data rate under the previous iteration meet the error specification.

9. A computer device comprising a memory and a processor, the memory having stored therein a computer program which, when executed by the processor, causes the processor to carry out the steps of the beamforming method as claimed in any of the claims 1 to 5.

10. A computer readable storage medium, having stored thereon a computer program which, when executed by a processor, causes the processor to carry out the steps of the beamforming method as claimed in any of the claims 1 to 5.

Technical Field

The invention belongs to the field of wireless communication, and particularly relates to a beam forming method, a beam forming device, computer equipment and a storage medium.

Background

As a revolutionary technology, Intelligent Reflective Surfaces (IRS) have received a great deal of attention from both academia and industry because of the ability to improve the spectrum and energy efficiency of wireless communication systems through preprogrammed controllers. IRS is equipped with a large number of elements made of special materials, passive reflection being achieved by adjusting the reflection coefficient (i.e. phase or amplitude) of the incident radio frequency wave. The signal reflected by the IRS may be summed with other signal paths to increase signal strength at the desired receiver or to mitigate co-channel interference for unintended users. The existing research results show that the IRS technology is expected to improve the spectrum efficiency and the energy utilization rate of an IRS auxiliary wireless system. For example, active Transmit Precoding (TPC) of a Base Station (BS) and passive beamforming at the IRS are jointly optimized to achieve certain performance metrics, such as maximizing channel capacity and physical layer security rate, and minimizing transmission delay and total transmit power. Another effective technique for improving spectrum utilization is Cognitive Radio (CR), which is considered as a technique that makes spectrum sharing possible in future wireless communication systems. However, a challenge of the CR system is that the performance improvements of the master user (PU) and the Slave User (SU) are conflicting. In particular, to improve the performance of the SU, the transmit power of the SU Transmitter (ST) should be increased to enhance the signal strength of the SU Receiver (SR), which will increase the interference to the PU Receiver (PR). Fortunately, this problem can be solved by introducing an IRS in the CR system, since the IRS can help increase the desired signal strength of the SU and mitigate co-channel interference to the PU by jointly optimizing TPC and phase shift. However, the existing techniques are mostly based on the assumption of full Channel State Information (CSI) at the transmitting end. However, estimating the channels associated with the IRS, e.g., from BS to IRS (BS-IRS) and IRS to user (IRS-user), is difficult because the IRS is passive and neither transmits nor receives pilot symbols. This challenge is more severe in IRS-assisted CR systems, since the channel from ST to PR is more difficult to estimate due to the collision relationship between PU and SU.

A concatenated BS-IRS user channel is estimated, which is the product of the BS-IRS channel and the IRS-user channel. Since the IRS does not need an active radio frequency chain, estimating the concatenated BS-IRS user channel is more cost-effective. However, in IRS-assisted communication systems, channel estimation errors are inevitable due to the channel estimation challenges. The impact on system performance should be taken into account when designing the transmission scheme. Therefore, it is necessary to study the robust beamforming design of IRS assisted wireless systems, taking into account channel estimation errors.

Zhou et al studied the worst case robust beamforming design of an IRS-assisted multi-user MISO system under the assumption of incomplete CSI, with the aim of minimizing the transmit power of the BS by jointly optimizing TPC and phase shift; yu and the like research the robust beam forming design of a multi-antenna potential eavesdropper with unknown CSI under the worst condition, and provide a joint design method of a beam forming vector and an artificial noise covariance matrix in order to improve the safety of a system; however, both algorithms are difficult to implement because the IRS requires additional active elements. Zhou et al use a cascade channel estimation method, wherein a frame for robust transmission beam forming is proposed based on an incomplete cascade IRS-related channel at a transmitter, and an S-procedure method and a Bernstein-type inequality are used to respectively approach a rate constraint and a rate interruption probability constraint under the worst case, and solve an optimization problem. However, such robust beamforming design may not be suitable for CR networks. Xu and the like respectively research a robust beam forming method for maximizing system capacity of a cognitive radio system under the assistance of an intelligent reflecting surface, but only consider a direct channel between a PU and an ST and do not consider an indirect channel passing through an IRS. The Jie Yuan and the like also consider introducing an intelligent reflecting surface in a multi-input single-output (MISO) cognitive radio system to research a beam forming method for maximizing the data rate of a slave user when channel state information between a PU and an SU has errors, but the method cannot guarantee the service quality requirement of the slave user.

Therefore, the problems that the optimized robustness cannot be guaranteed and the service quality requirement of the slave user cannot be guaranteed exist in the conventional beam forming method.

Disclosure of Invention

The embodiment of the invention aims to provide a beam forming method, aiming at solving the problems that the optimized robustness of the existing beam forming method cannot be ensured and the service quality requirement of a slave user cannot be ensured.

The embodiment of the invention is realized in such a way that a beam forming method comprises the following steps:

determining a signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmission precoding matrix;

determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix;

and solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

Another objective of an embodiment of the present invention is to provide a beamforming apparatus, including:

the signal-to-noise ratio determining unit is used for determining the signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmitting precoding matrix;

the interference temperature determining unit is used for determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix; and

and the optimal matrix determining unit is used for solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

It is a further object of embodiments of the invention a computer device comprising a memory and a processor, the memory having stored therein a computer program which, when executed by the processor, causes the processor to perform the steps of the beamforming method.

Another object of an embodiment of the present invention is a computer readable storage medium having a computer program stored thereon, which, when executed by a processor, causes the processor to perform the steps of the beamforming method.

The beam forming method provided by the embodiment of the invention assists the slave users to communicate by adopting the intelligent reflecting surface in the cognitive radio system, and establishes the optimization of beam forming under the condition that channel errors exist between the master users and the slave users, and the active transmitting pre-coding matrix and the intelligent reflecting surface phase shift matrix are jointly carried out. The invention can obtain the optimal slave user sending precoding and the optimal intelligent reflecting surface phase within the allowed range of master user interference temperature and under the requirement of the minimum rate of the slave user receiving end when the slave user does not obtain perfect channel information between the master user and the slave user, thereby achieving the purpose of minimum slave user sending total power.

Drawings

Fig. 1 is a schematic structural diagram of a cognitive radio network system according to an embodiment of the present invention;

fig. 2 is a flowchart of a beamforming method according to an embodiment of the present invention;

fig. 3 is a flowchart of another beamforming method according to an embodiment of the present invention;

fig. 4 is a flowchart of another beamforming method according to an embodiment of the present invention;

fig. 5 is a flowchart of another beamforming method according to an embodiment of the present invention;

fig. 6 is a block diagram of a beam forming apparatus according to an embodiment of the present invention;

fig. 7 is a block diagram of an interference temperature determining unit in a beamforming apparatus according to an embodiment of the present invention;

fig. 8 is a block diagram of an optimal matrix determining unit in a beamforming apparatus according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, an application environment diagram of a beamforming method provided in the embodiment of the present invention may also be understood as a schematic structural diagram of a cognitive radio network system, which is described in detail as follows.

In the embodiment of the present invention, the cognitive radio network system includes a Secondary Transmitter (ST), K Secondary Receivers (SR), a Primary Receiver (PR), and an Intelligent Reflection Surface (IRS).

As shown in fig. 2, in an embodiment, a beamforming method is provided, and this embodiment is mainly illustrated by applying the method to the cognitive radio network system in fig. 1, and specifically may include the following steps:

step S201, according to the channel from the user transmitter to the user receiver, the reflection channel from the intelligent reflection surface to the user receiver, the channel from the user transmitter to the intelligent reflection surface, the intelligent reflection surface phase shift matrix and the active transmission precoding matrix, determining the signal-to-noise ratio of each slave user receiver.

In an embodiment of the invention, the IRS consists of N reflective elements, each element being represented by phi_n＝e^jθnN ∈ N ═ {1, 2.., N } denotes where j is an imaginary unit, θ_n∈[0,2π]Is the phase shift of the Nth element, phi_nHas a unit modulus, i.e., | φ n | ═ 1. Reflection element diagonalization matrix phi ═ diag { phi [ ]₁,φ₂,...,φ_NNamed Reflection Element Diagonalization (RED) matrix. The slave user transmission link shares spectrum resources with the master user transmission link. Number of antennas of ST being M_tPR and SR k (kth SR) are all single antennas. Are used separately(The expression size is NxM_tThe complex matrix of (a),representing the path from ST to IRS, PR, and SR K (i.e., the kth SR, K ∈ K ═ 1, 2. The reflection paths from IRS to PR and SR k are respectively represented by g_r∈C^N×1And h_r,k∈C^N×1And (4) showing.

S for desired signal of SR k_kE C denotes that it has a corresponding TPC vectorAccording to the principle of orthogonality, Es_ks^* _k]＝1，E[s_is^* _j]0(i ≠ j). For TPC matricesTo indicate. The transmitted signal from the ST can then be written asThe received signal at SR k can be represented byRepresents, where H represents the conjugate transpose of the matrix,interference signals received at PRIs shown in whichThus, the signal-to-noise ratio (SINR) of SR k is:

wherein phi is [ phi ]₁,φ₂,...,φ_N]^T，W_-k＝[w₁,...,w_k-1,w_k+1,w_k]。

Step S202, according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and the active transmitting pre-coding matrix, determining the interference temperature applied to the main user receiver.

In the embodiment of the present invention, the disturbance temperature (IT) imposed on PR (neglecting noise) is:

in the formula (I), the compound is shown in the specification,is a concatenated channel from ST to PR through IRS.

In this embodiment of the present invention, as shown in fig. 3, the step S202 specifically includes:

step S301, a cascade channel from a user transmitter to a main user receiver and a channel from the user transmitter to the main user receiver through an intelligent reflecting surface are integrated into a channel equivalent combination form.

In the embodiment of the present invention, the above two channels are further integrated into an equivalent combination form denoted by G:

therefore, (2) can be expressed in another form:

in the formula (I), the compound is shown in the specification,

step S302, according to the channel equivalent combination form and the uncertainty of the channel, obtaining the estimated comprehensive channel state information and the comprehensive channel state information error matrix from the user transmitter.

Step S303, according to the estimated comprehensive channel state information, the comprehensive channel state information error matrix, the intelligent reflecting surface phase shift matrix and the active transmitting pre-coding matrix at the slave user transmitter, determining the interference temperature applied to the master user receiver.

In an embodiment of the present invention, the uncertainty of the channel can be modeled as:

whereinAndare respectively direct channels g_dAnd a cascade channelG_rEstimated CIS (channel state information). Δ g_d，ΔG_rIs the corresponding CSI error. The uncertainty of channel G can be modeled as:

in the formulaIs the estimated integrated CSI at ST, Δ G is the integrated CSI error matrix. Thus, (4) can be written as:

substituting (5) into (3) and (6)Δ G in (1) and (7) can be expressed as:

and S203, solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

In this embodiment of the present invention, as shown in fig. 4, the step S203 includes:

step S401, based on the bounded channel state information error model, an initial active transmitting pre-coding matrix and an initial intelligent reflecting surface phase shift matrix are preset randomly.

S402, fixing the initial intelligent reflecting surface phase shift matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams, and solving and optimizing an active transmitting precoding matrix;

step S403, fixing the initial active transmitting pre-coding matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams, and solving an optimized intelligent reflecting surface phase shift matrix;

step S404, judging whether the current data rate and the data rate under the previous iteration meet the error regulation, if not, taking the optimized active transmitting precoding matrix and the optimized intelligent reflecting surface phase shift matrix as a new generation of initial active transmitting precoding matrix and a new generation of intelligent reflecting surface phase shift matrix, and returning to the step S402; if yes, the process proceeds to step S405.

Step S405, determining the current optimized active transmitting pre-coding matrix and the optimized intelligent reflecting surface phase shift matrix as an optimal active transmitting pre-coding matrix and an optimal intelligent reflecting surface phase shift matrix.

In an embodiment of the invention, the bounded CSI error model: in this model, the CSI errors for the direct channel and the concatenated channel are assumed to be bounded in the following regions:

||Δg_d||₂≤ε_d,||G_r||_F≤ε_r。 (9)

wherein epsilon_dAnd ε_rIs the radius of the CSI error bounded region. Based on the above assumptions, we have:

based on the above scenario, by optimizing the TPC matrix W and RED matrix Φ, the total transmit power of ST is minimized according to the unit mode of reflected beam forming, SINR requirements of each SR, and restrictions on PR. Thus, the optimization problem can be expressed as:

constraint conditions are as follows:

IT≤Γ， (11c)

in the problem (P0), (11b) is the QoS requirement per SR, where γ_kIs the minimum SINR of SR k, and can be considered asWherein r is_k(bit/s) is the corresponding desired data rate. Γ is the threshold for PR, (11c) guarantees that disturbances imposed on PR are acceptable. (11d) Is the IRS phase shift constraint and (11e) is the uncertain CSI constraint.

The problem is non-convex, the transmit precoding matrix and the phase shift matrix couple to each other and there is an uncertainty error. To decouple the uncertainty, we solve W and Φ alternately by finding the worst case reconstruction optimization problem.

The problem (P0) can be restated as:

constraint conditions are as follows:

the bounded CSI error based optimization problem is translated into a deterministic problem. Wherein the content of the first and second substances, w and Φ are alternately optimized by mutual fixation with an alternating algorithm. Recording the t-th iteration calculation to obtain a precoding matrix and a phase shift matrix which are divided into W^(t)And phi^(t)When optimizing W, assume Φ is known, and when optimizing Φ, assume W is known, then each is solved. The solution is as follows:

write a sub-problem of fixed Φ optimized W:

constraint conditions are as follows:

wherein the content of the first and second substances,this problem is a second order cone planning problem that can be solved with a convex optimization tool.

Write a sub-problem of fixed W optimized φ:

constraint conditions are as follows:

φ^HBφ+2Re{b^Hφ}≤Γ-(N+1)ξ-b_N+1, (14c)

wherein τ ═ τ [ τ ]₁,..,τ_2N]^TIs the relaxation variable of the phase constraint of the unit modulus, order toAnd extracting the first N rows and N columns of elements of X to form a submatrix B. Denote by b a vector consisting of elements in (N +1) columns of the first to nth rows of X, b_N+1Is X (N +1) th row and (N +1) th column element. Mu is used for scaling penalty term | | tau | | non-woven cells₁The penalty multiplier, which may be combined with adjusting μ to control the feasibility of φ. This sub-problem is a second order cone planning problem that can be solved with a convex optimization tool.

Assuming that the initial value t is 0, the maximum number of iterations t^max400. Any given slave user transmitting sumPower not higher than P_t(e.g., 1W); the interference power suffered by the primary user is not higher than gamma (for example, 10)^-13W). Recording the t-th iteration calculation to obtain a precoding matrix and a phase shift matrix which are divided into W^(t)And phi^(t)Setting error tolerance as 10^-5. Firstly, randomly generating an initial matrix W⁽⁰⁾And phi⁽⁰⁾The problem solving step is shown in fig. 5, and is detailed as follows:

step 1: initializationφ⁽⁰⁾Maximum number of iterations t_max400, the error tolerance value epsilon is set to 10^-5Setting the initial value t to 0, and stopping the operation under the condition₁＝10^-3,l₂＝10^-2Initial coefficient l_μ> 1, maximum penalty factor mu_max，

Step 2: calculation by solving problem (P1.1)Let phi⁽⁰⁾＝φ^(t)；

And step 3: calculating phi by solving the problem (P1.2)⁽ⁿ⁺¹⁾；

And 4, step 4: mu.s⁽ⁿ⁺¹⁾＝max{l_μμ⁽ⁿ⁾,μ_max}；

And 5: n is n + 1;

step 6: satisfy | | τ | luminance₁≤l₁，||φ⁽ⁿ⁺¹⁾-φ⁽ⁿ⁾||₁≤l₂Stopping; otherwise, returning to the step 3;

and 7: phi is a^(t+1)＝φ⁽ⁿ⁺¹⁾；

And 8: computing from an objective function in a problem (P1)

Step (ii) of9: satisfy t > t_maxOrStopping; otherwise, returning to the step 2.

Step 10: outputting an optimal transmit precoding matrix W^*＝W^(t+1)And optimal phase shift array phi^*＝Φ^(t+1)。

The experimental conditions (system parameters) corresponding to the embodiments of the present invention are shown in table 1 below:

TABLE 1

The beam forming method provided by the embodiment of the invention assists the slave users to communicate by adopting the intelligent reflecting surface in the cognitive radio system, and establishes the optimization of beam forming under the condition that channel errors exist between the master users and the slave users, and the active transmitting pre-coding matrix and the intelligent reflecting surface phase shift matrix are jointly carried out. According to the bounded limitation of channel errors, on one hand, the receiving rate of the slave user receiver is ensured, on the other hand, the interference suffered by the master user receiver is ensured to be within a tolerable range, so that the phase shift of the intelligent reflecting surface is properly adjusted, and a proper precoding array is designed at the slave user transmitter, so that the minimum total transmitting power of the slave user transmitter is realized. The invention can obtain the optimal slave user sending precoding and the optimal intelligent reflecting surface phase within the allowed range of master user interference temperature and under the requirement of the minimum rate of the slave user receiving end when the slave user does not obtain perfect master-slave user channel information, thereby achieving the purpose of minimum slave user sending total power and solving the problems that the master user interference temperature is limited and the total power of the slave user sending end is further reduced under the requirement of the minimum rate of the slave user under the condition that the master user interference temperature has errors in the master-slave user channel state information.

Specifically, (1) compared with the conventional cognitive radio system without the aid of the intelligent reflecting surface, the method can remarkably reduce the total transmitting power of the slave users by jointly optimizing the transmitting precoding matrix and the phase shift matrix when the estimation error of the master user channel is bounded, for example, when the number of the phase shift elements is 30, the power can be reduced by 2.3dB, and under the condition that other parameters are unchanged, the number of the phase shift elements is increased, and the power can be further reduced. (2) Compared with the cognitive wireless system with the assistance of the intelligent transmitting surface and fixed or random phase shift elements, the method can obviously reduce the total transmitting power of the slave users by optimizing the phase shift matrix when the estimation error of the master user channel is bounded, for example, when the number of the phase shift elements is 30, the power can be reduced by 1.3dB, and under the condition that other parameters are unchanged, the number of the phase shift elements is increased, and the power can be further reduced. (3) When the error of the primary user channel is limited, the transmission power of the secondary user is reduced along with the increase of the error level, but the feasible domain of beam forming is smaller, and the optimal transmission precoding matrix and the optimal phase shift matrix are not easy to find. For example, when the error level value is 0.1, the set phase shift number is 6, the requirement of the rate of the slave user is 2 bits/s/Hz, the interference threshold of the master user is minus 80dbm, the number of the slave user transmitting antennas is 10, the feasible region is about 91%, and the total transmitting power is about 17.5 dB; but when the error level value increases to 0.2, the total transmit power only drops to 17.1dB, while the feasible region drops to 45%. (4) When the error of the main user channel is limited, the transmission power of the secondary user is reduced along with the increase of the element of the intelligent reflection surface, but the feasible domain of beam forming is smaller, and the optimal transmission precoding matrix and the optimal phase shift matrix are not easy to find. For example, when the phase shift number is 10, the number of the slave user transmitting antennas is set to be 6, the slave user rate requirement is 2 bits/s/Hz, the master user interference threshold is-80 dbm, the channel error level is 0.1, the feasible region is about 80%, and the total transmitting power is about 19.8 dB; but when the number of phase shifts is increased to 15, the total transmit power is only reduced to 19.5dB and the feasible region is reduced to 39%.

As shown in fig. 6, in an embodiment, a beamforming apparatus is provided, which may specifically include:

a signal-to-noise ratio determining unit 610, configured to determine a signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflective surface to the slave user receiver, a channel from the user transmitter to the intelligent reflective surface, the intelligent reflective surface phase shift matrix, and the active transmit precoding matrix.

And an interference temperature determining unit 620, configured to determine an interference temperature applied to the primary user receiver according to a cascade channel from the user transmitter to the primary user receiver through the intelligent reflective surface, a channel from the user transmitter to the intelligent reflective surface, and the active transmit precoding matrix.

And an optimal matrix determining unit 630, configured to solve an optimal active transmit precoding matrix and an optimal intelligent reflection surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver, and the unit modulus formed by the reflection beam.

As shown in fig. 7, in an embodiment, the interference temperature determination unit 620 includes:

and a channel integration module 621, configured to integrate a cascade channel from the user transmitter to the main user receiver and a channel from the user transmitter to the main user receiver via the intelligent reflective surface into a channel equivalent combination.

An error matrix obtaining module 622, configured to obtain the estimated integrated channel state information and the integrated channel state information error matrix from the user transmitter according to the channel equivalent combination form and the uncertainty of the channel.

And an interference temperature determining module 623, configured to determine an interference temperature applied to the primary user receiver according to the estimated integrated channel state information, the integrated channel state information error matrix, the intelligent reflecting surface phase shift matrix, and the active transmit precoding matrix at the secondary user transmitter.

As shown in fig. 8, in an embodiment, the optimal matrix determining unit 630 includes:

and a preset initial matrix module 631, configured to randomly preset an initial active transmit precoding matrix and an initial intelligent reflection surface phase shift matrix based on the bounded channel state information error model.

And an optimized active transmission precoding matrix solving module 632, configured to fix the initial intelligent reflecting surface phase shift matrix according to the signal-to-noise ratio of each secondary user receiver, the interference temperature applied to the primary user receiver, and the unit modulus formed by the reflected beam, and solve the optimized active transmission precoding matrix.

And the optimized intelligent reflecting surface phase shift matrix solving module 633 is used for fixing the initial active transmitting precoding matrix and solving the optimized intelligent reflecting surface phase shift matrix according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

A first determining module 634, configured to, when it is determined that the current data rate and the data rate under the previous iteration do not meet the error specification, use the optimized active transmit precoding matrix and the optimized intelligent reflective surface phase shift matrix as a new generation of initial active transmit precoding matrix and a new generation of intelligent reflective surface phase shift matrix, and return to the step of fixing the initial intelligent reflective surface phase shift matrix and solving the optimized active transmit precoding matrix according to the signal-to-noise ratio of each secondary user receiver, the interference temperature applied to the primary user receiver, and the unit modulus formed by the reflected beams.

The second determining module 635 is configured to determine the currently optimized active transmit precoding matrix and the optimized intelligent reflective surface phase shift matrix as an optimal active transmit precoding matrix and an optimal intelligent reflective surface phase shift matrix when it is determined that the current data rate and the data rate in the previous iteration satisfy the error specification.

The beam forming device provided by the embodiment of the invention assists the slave users to communicate by adopting the intelligent reflecting surface in the cognitive radio system, establishes the optimization of beam forming under the condition that channel errors exist between the master users and the slave users, and jointly performs the beam forming by actively transmitting a pre-coding matrix and the intelligent reflecting surface phase shift matrix. According to the bounded limitation of channel errors, on one hand, the receiving rate of the slave user receiver is ensured, on the other hand, the interference suffered by the master user receiver is ensured to be within a tolerable range, so that the phase shift of the intelligent reflecting surface is properly adjusted, and a proper precoding array is designed at the slave user transmitter, so that the minimum total transmitting power of the slave user transmitter is realized.

In one embodiment, a computer device is proposed, the computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the computer program:

determining a signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmission precoding matrix;

determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix;

and solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

In one embodiment, a computer readable storage medium is provided, having a computer program stored thereon, which, when executed by a processor, causes the processor to perform the steps of:

determining a signal-to-noise ratio of each slave user receiver according to a channel from the user transmitter to the slave user receiver, a reflection channel from the intelligent reflecting surface to the slave user receiver, a channel from the user transmitter to the intelligent reflecting surface, an intelligent reflecting surface phase shift matrix and an active transmission precoding matrix;

determining the interference temperature applied to the main user receiver according to a cascade channel from the user transmitter to the main user receiver through the intelligent reflecting surface, a channel from the user transmitter to the intelligent reflecting surface and an active transmitting precoding matrix;

and solving an optimal active transmitting precoding matrix and an optimal intelligent reflecting surface phase shift matrix based on a bounded channel state information error model according to the signal-to-noise ratio of each slave user receiver, the interference temperature applied to the master user receiver and the unit modulus formed by the reflected wave beams.

It should be understood that, although the steps in the flowcharts of the embodiments of the present invention are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in various embodiments may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.