阅读说明：本技术 一种智能反射面反射系数与偏置电压关系的测量方法 (Method for measuring relation between reflection coefficient of intelligent reflecting surface and bias voltage ) 是由 党建 朱宏伟 张在琛 吴亮 朱秉诚 汪磊 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种智能反射面反射系数与偏置电压关系的测量方法,该方法测量了智能反射面不同偏置电压的反射系数与参考电压对应的反射系数的关系。基于信道相干时间内信道恒定的特性,在信道相干时间内,控制器先将智能反射面的偏置电压恒定设置为参考电压,然后恒定设置为偏置电压范围内的任意待测电压值。发送端发送恒包络信号,接收端接收智能反射面反射后的信号,对接收信号进行处理得到待测偏置电压对应的反射系数与参考偏置电压对应的反射系数的比值。为了减少噪声对测量结果的影响,在测量过程中对接收信号多个样值取均值。本发明提供了低复杂度、低成本的智能反射面的反射系数与偏置电压关系的测量方法。(The invention discloses a method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage. Based on the constant characteristic of the channel in the channel coherence time, the controller firstly sets the bias voltage of the intelligent reflecting surface to be constant as reference voltage and then sets the bias voltage to be constant as any voltage value to be measured in the bias voltage range in the channel coherence time. The sending end sends a constant envelope signal, the receiving end receives the signal reflected by the intelligent reflecting surface, and the received signal is processed to obtain the ratio of the reflection coefficient corresponding to the bias voltage to be measured to the reflection coefficient corresponding to the reference bias voltage. In order to reduce the effect of noise on the measurement results, a plurality of samples of the received signal are averaged during the measurement. The invention provides a method for measuring the relation between the reflection coefficient and the bias voltage of an intelligent reflecting surface with low complexity and low cost.)

1. A method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage is characterized by comprising the following steps:

step 1, one transmitting antenna and N_REach receiving antenna is respectively aligned with an intelligent reflecting surface with M units, N_RNot less than 1; the continuous transmitting frequency of the transmitting end is f_cOf (a) carrier signal x (t) ═ Acos2 pi f_ct, t is the signal duration, A is the carrier signal amplitude; the receiving end controls the bias voltage of the intelligent reflecting surface and samples the received signal; the bias voltages of all units are configured to be the same voltage value at the same time;

step 2, the bias voltage range of the intelligent reflecting surface is [ v ]₀，v_M]Wherein v is₀Is the minimum value of the bias voltage, v_MIs the bias voltage maximum; will bias the voltage v₀Defined as a reference voltage, which corresponds to a reflection coefficient alpha₀Defined as the reference reflection coefficient, measuring and calculating an arbitrary voltage v_i∈[v₀，v_M]Corresponding reflection coefficient alpha_iAnd alpha₀The ratio of (A) to (B);

step 3, repeating the step 2 and constantly setting the bias voltage of the intelligent reflecting surface in the step 2 to be V₀，v_M]Obtaining reflection coefficients and alpha corresponding to different bias voltages at different voltage values₀The relationship (2) of (c).

2. The method for measuring the relation between the reflection coefficient of the intelligent reflecting surface and the bias voltage according to claim 1, wherein the step 2 is used for measuring and calculating any voltage v_i∈[v₀，v_M]Corresponding reflection coefficient alpha_iAnd alpha₀The specific ratio of (A) to (B) specifically comprises the following steps:

step 2.1, the channel coherence time is T, and the channel coherence time is divided into T₀And T₁Two time periods in which T is satisfied₀+T₁T; in the channel coherence time T, the equivalent low-pass channel from the mth unit of the intelligent reflecting surface to the transmitting end antenna is recorded as T_mThe equivalent low-pass channel from the mth unit of the intelligent reflector to the mth antenna of the receiver is recorded asAt T₀During which the bias voltage of the intelligent reflecting surface is constantly set to v₀To N, to_RThe signal received by each receiving antenna is subjected to carrier demodulation and equal-interval sampling, and the number of sampling points is recorded as N₀，N₀Not less than 1; the sampling value is expressed as

k＝1，2，...，N₀，r＝1，2，...，N_R

Which is composed ofIs T₀During which the receiving end demodulates and samples the kth sampling value of the signal received by the r antenna port,is T₀During the period of the k sampling value of the r radio frequency channel additive white Gaussian noise process; taking the mean value of the sample values of the received signal as the actual received signalIs shown as

Step 2.2, at T₁During the period, the bias voltage of the intelligent reflecting surface is constantly set to be v₁，v₁Corresponding reflection coefficient of alpha₁(ii) a To N_RSampling after demodulating the signal received by each receiving antenna, and recording the number of sampling points as N₁，N₁Is greater than or equal to 1, and the sampling value is expressed as

k＝1，2，...，N₁，r＝1，2，...，N_R

WhereinIs T₁During which the receiving end demodulates and samples the kth sampling value of the signal received by the r antenna port,is T₁During the period of the k sampling value of the r radio frequency channel additive white Gaussian noise process; taking a received signal N₁The mean value of the individual sample values is used as the actual received signal of the r-th antennaIs shown as

Step 2.3, the reflection coefficient relation is established as follows:

the above formula is v₀And v₁Alpha of the corresponding reflection coefficient₀And alpha₁The relationship (2) of (c).

3. The method for measuring the relation between the reflection coefficient of the intelligent reflecting surface and the bias voltage as claimed in claim 1 or 2, wherein the frequency f of the carrier signal is traversed_cRepeating the steps 1 to 3 to obtain different signal frequencies f_cThe corresponding reflection coefficient versus bias voltage.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a method for measuring the corresponding relation between an intelligent reflecting surface reflection coefficient and bias voltage.

Background

The demand for high-rate communication by mobile communication services has promoted the birth and application of 5 th generation mobile communication (5G) technology, and 5G communication systems are becoming an important component of a new generation of information infrastructure. While the 5G communication system is deployed in a large scale, the new problems of cost increase, power consumption increase and the like are faced. To solve these problems, new technical means are needed.

An Intelligent Reflection Surface (IRS), or a Reconfigurable Intelligent Surface (RIS), provides a feasible technical approach to solve the above problems. The IRS is a super-surface composed of a large number of low-cost passive elements, and can improve the transmission performance of a communication system by changing the propagation environment of electromagnetic waves. In conventional wireless communication, communication quality is affected by a propagation environment, i.e., a channel, which cannot be actively controlled and changed by a transmitting and receiving end. The IRS can change the propagation environment of the channel to a large extent through independently adjusting the reflection coefficient of each unit and the synergistic effect of a plurality of reflection units, so that the effect of actively regulating and controlling the channel is achieved.

In order to maximize the function of the IRS and improve the performance of the deployed IRS communication system, it is necessary to set the reflection coefficients of a large number of units of the IRS reasonably. Currently, each unit of the typical IRS is formed by a varactor diode and is connected to a main controller, and the main controller adjusts the bias voltage of the varactor diode to change the impedance of the unit, thereby adjusting the reflection coefficient of the signal. Therefore, before deploying the IRS in the communication system, the corresponding relationship between the bias voltage and the reflection coefficient of the IRS unit needs to be established in advance.

The existing reflection coefficient and bias voltage relation measuring scheme is mainly divided into two types: one scheme is to obtain a relation graph of bias voltage and reflection coefficient through software simulation. In practice, due to errors of a plate making process and deviations of actual values and nominal values of electronic components, a result obtained by software simulation may have large deviations from the relationship between an actual reflection coefficient and bias voltage; another solution is to perform the measurement in a microwave dark room, which requires the use of specialized and expensive equipment and is therefore costly. In practical use, how to measure the relationship between IRS reflection phase and bias voltage easily and quickly at low cost is an important issue to be solved at present.

Disclosure of Invention

The invention aims to provide a method for measuring the relation between the reflection coefficient of an intelligent reflection surface and bias voltage, so as to solve the technical problem of simply and quickly measuring the relation between the IRS reflection phase and the bias voltage at low cost.

In order to solve the technical problems, the specific technical scheme of the invention is as follows:

a method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage comprises the following steps:

step 1, one transmitting antenna and N_REach receiving antenna is respectively aligned with an intelligent reflecting surface with M units, N_RNot less than 1; the continuous transmitting frequency of the transmitting end is f_cOf (a) carrier signal x (t) ═ Acos2 pi f_ct, t is the signal duration, A is the carrier signal amplitude; the receiving end controls the bias voltage of the intelligent reflecting surface and samples the received signal; the bias voltages of all units are configured to be the same voltage value at the same time;

step 2, the bias voltage range of the intelligent reflecting surface is [ v ]₀，v_M]Wherein v is₀Is the minimum value of the bias voltage, v_MIs the bias voltage maximum; will bias the voltage v₀Defined as a reference voltage, which corresponds to a reflection coefficient alpha₀Defined as the reference reflection coefficient, measuring and calculating an arbitrary voltage v_i∈[v₀，v_M]Corresponding reflection coefficient alpha_iAnd alpha₀The ratio of (A) to (B);

step 3, repeating the step 2 and constantly setting the bias voltage of the intelligent reflecting surface in the step 2 to be V₀，v_M]Obtaining reflection coefficients and alpha corresponding to different bias voltages at different voltage values₀The relationship (2) of (c).

Further, in step 2, an arbitrary voltage v is measured and calculated_i∈[v₀，v_M]Corresponding reflection coefficient alpha_iAnd alpha₀The specific ratio of (A) to (B) specifically comprises the following steps:

step 2.1, the channel coherence time is T, and the channel coherence time is divided into T₀And T₁Two time periods in which T is satisfied₀+T₁T; in the channel coherence time T, the equivalent low-pass channel from the mth unit of the intelligent reflecting surface to the transmitting end antenna is recorded as T_mThe equivalent low-pass channel from the mth unit of the intelligent reflector to the mth antenna of the receiver is recorded asAt T₀During which the bias voltage of the intelligent reflecting surface is constantly set to v₀To N, to_RThe signal received by each receiving antenna is subjected to carrier demodulation and equal-interval sampling, and the number of sampling points is recorded as N₀，N₀Not less than 1; the sampling value is expressed as

WhereinIs T₀During which the receiving end demodulates and samples the kth sampling value of the signal received by the r antenna port,is T₀During the period of the k sampling value of the r radio frequency channel additive white Gaussian noise process; taking the mean value of the sample values of the received signal as the actual received signalIs shown as

Step 2.2, at T₁During the period, the bias voltage of the intelligent reflecting surface is constantly set to be v₁，v₁Corresponding reflection coefficient of alpha₁(ii) a To N_RSampling after demodulating the signal received by each receiving antenna, and recording the number of sampling points as N₁，N₁Is greater than or equal to 1, and the sampling value is expressed as

WhereinIs T₁During which the receiving end demodulates and samples the kth sampling value of the signal received by the r antenna port,is T₁During the period of the k sampling value of the r radio frequency channel additive white Gaussian noise process; taking a received signal N₁The mean value of the individual sample values is used as the actual received signal of the r-th antennaIs shown as

Step 2.3, the reflection coefficient relation is established as follows:

the above formula is v₀And v₁Alpha of the corresponding reflection coefficient₀And alpha₁The relationship (2) of (c).

Further, the carrier signal frequency f is traversed_cRepeating the steps 1 to 3 to obtain different signal frequenciesRate f_cThe corresponding reflection coefficient versus bias voltage.

The invention discloses a method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage, which has the following advantages:

(1) compared with the existing measuring method, the method for measuring the relation between the reflection coefficient of the intelligent reflecting surface and the bias voltage has low requirement on the testing environment, does not need professional measuring environments such as a microwave darkroom and the like and professional equipment such as a waveguide simulator and the like, and reduces the cost of a measuring system.

(2) In the testing method provided by the invention, all unit bias voltages of the intelligent reflecting surface are the same at the same time, the design of a voltage control circuit used for testing is simpler, and the increase of the number of units does not improve the measurement complexity, so that the measuring scheme has universality for the intelligent reflecting surfaces with different numbers of units.

Drawings

FIG. 1 is a schematic diagram of an intelligent reflective surface reflectance measurement system of the present invention;

FIG. 2 is a diagram of the intelligent reflector bias voltage setting during the channel coherence time of the present invention;

FIG. 3 is a graph comparing the measurement results and the theoretical results of the first and second examples;

the notation in the figure is: 1. a sending end; 2. a receiving end; 3. a controller; 4. an intelligent transmitting surface; 5. a transmitting unit; 6. and a receiving antenna.

Detailed Description

In order to better understand the purpose, structure and function of the present invention, the following describes the method for measuring the relationship between the reflection coefficient of the intelligent reflection surface and the bias voltage in detail with reference to the accompanying drawings.

In the first embodiment, as shown in fig. 1, the measurement system for measuring the reflection coefficient of the intelligent reflection surface includes a transmitting end 1 configured with a horn antenna, and a configuration N_RA receiving end 2 of each horn antenna and M unit intelligent reflecting surfaces 4. Wherein N is_R3, M16. According to the maximum reverse working voltage of the variable capacitance diode in the intelligent reflecting surface transmitting unit 5, the intelligent reflection is carried outThe bias voltage of the surface 4 is set at 0V, 30V]. The invention provides a method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage, which specifically comprises the following steps:

step 1, respectively aligning a transmitting antenna and three receiving antennas 6 to the intelligent reflecting surface 4. The continuous transmitting frequency of the transmitting end 1 is f_cOf (a) carrier signal x (t) ═ Acos2 pi f_ct, a is the carrier signal amplitude. The receiving end 2 samples the received signal and adjusts the reflection coefficient of the intelligent reflecting surface 4 through the controller. In particular, the bias voltages of all cells are configured to be the same at the same time. The bias voltage 0V is used as a reference voltage and the corresponding reflection coefficient alpha₀Defined as the reference reflection coefficient, measuring and calculating an arbitrary voltage v_i∈[0V，30V]Corresponding reflection coefficient alpha_iIn this embodiment, it is assumed that all reflection coefficients have a modulus value of 1;

step 2, assuming the channel coherence time is T, dividing it into T₀And T₁Two time periods, satisfy T₀+T₁T. As shown in fig. 1, in a certain channel coherence time T, equivalent low-pass channels from the mth transmitting unit 5 of the intelligent reflecting surface 4 to the transmitting end antenna and the mth receiving end antenna are respectively marked as T_mAndas shown in fig. 2, at T₀The bias voltage of the intelligent reflecting surface 4 is constantly set to 0V for N_RThe signal received by the receiving antenna 6 is subjected to carrier demodulation and equal interval sampling, and the number of sampling points is recorded as N₀，N₀20. The sampling value is expressed as

WhereinIs T₀During which the receiving end demodulates and samples the kth sample of the signal received at the r-th antenna port,is T₀During which the kth sample of the r-th radio frequency channel additive white gaussian noise process. To reduce the effect of noise, the mean value of the sample values of the received signal is taken as the actual received signalIs shown as

As shown in fig. 2, at T₁The bias voltage of the intelligent reflecting surface 4 is constantly set to 2V in the period, and the reflection coefficient corresponding to the bias voltage 2V is assumed to be alpha₁。N_RSampling after demodulating the signal received by each receiving antenna, and recording the number of sampling points as N₁,N₁＝N₀. The sampling value is expressed as

WhereinIs T₁During which the receiving end demodulates and samples the kth sampling value of the signal received by the r antenna port,is T₁During which the kth sample of the r-th radio frequency channel additive white gaussian noise process. Taking a received signal N₁The mean value of the individual sample values is used as the actual received signal of the r-th antennaIs shown as

The reflection coefficient relationship is established as:

the above expression is α of the reflection coefficient corresponding to the bias voltages 0V and 2V₀And alpha₁The relationship of (1);

step 3, repeating step 2 and repeating T in step 2₁The bias voltage of the intelligent reflecting surface is constantly set to 0V and 30V]The values of the bias voltages are shown in FIG. 3, and the reflection coefficients and alpha corresponding to different bias voltages under the same carrier signal frequency are obtained₀The relationship of (1);

step 4, the reflection coefficient is not only related to the bias voltage, but also related to the carrier signal frequency. Optionally, the carrier signal frequency f is traversed_cRepeating the steps 1, 2 and 3 to obtain different signal frequencies f_cThe corresponding reflection coefficient versus bias voltage.

Example two:

the system for measuring the reflection coefficient of the intelligent reflecting surface comprises a transmitting end 1 provided with a horn antenna and a configuration N_RA receiving end 2 of each horn antenna and M unit intelligent reflecting surfaces 4. Wherein N is_R1, and 16. The bias voltage of the intelligent reflecting surface 4 is set to be 0V and 30V according to the maximum reverse working voltage of the variable capacitance diode in the intelligent reflecting surface transmitting unit 5]. The invention provides a method for measuring the relation between the reflection coefficient of an intelligent reflecting surface and bias voltage, which specifically comprises the following steps:

step 1, respectively aligning a transmitting antenna and a receiving antenna 6 to an intelligent reflecting surface 4. The continuous transmitting frequency of the transmitting end 1 is f_cOf (a) carrier signal x (t) ═ Acos2 pi f_ct, a is the carrier signal amplitude. The receiving end 2 controls the bias voltage of the intelligent reflecting surface 4 and samples the received signal. In particular, the bias voltages of all cells are configured to be the same at the same time. The bias voltage 0V is used as a reference voltage and the corresponding reflection coefficient alpha₀Is defined as a referenceReflection coefficient, measuring and calculating any voltage v_i∈[0V，30V]Corresponding reflection coefficient alpha_iIn this embodiment, it is assumed that all reflection coefficients have a modulus value of 1;

step 2, assuming the channel coherence time is T, dividing it into T₀And T₁Two time periods in which T is satisfied₀+T₁T. In a certain channel coherence time T, the equivalent low-pass channels from the mth unit of the intelligent reflecting surface 4 to the transmitting end antenna and the receiving end antenna are respectively marked as T_mAnd g_m. As shown in fig. 2, at T₀During the period, the bias voltage of the intelligent reflecting surface 4 is constantly set to 0V, the signal received by the receiving antenna 6 is subjected to carrier demodulation and equal-interval sampling, and the number of sampling points is recorded as N₀，N₀1. The sampling value is expressed as

Wherein y is₀Is T₀The receiving end demodulates and samples the signal received by the antenna port during the period, n₀Is T₀During which the sampling values of the radio frequency channel additive white gaussian noise process.

As shown in fig. 2, at T₁The bias voltage of the intelligent reflecting surface 4 is constantly set to 2V in the period, and the reflection coefficient corresponding to the bias voltage 2V is assumed to be alpha₁. To N_RThe signal received by the receiving antenna 6 is sampled after demodulation, and the number of sampling points is recorded as N₁，N₁＝N₀. The sampling value is expressed as

Wherein y is₁Is T₁The receiving end demodulates and samples the signal received by the port of the receiving antenna 6 during the period, n is the sampling value₁Is T₁During which the sampling values of the radio frequency channel additive white gaussian noise process.

The reflection coefficient relationship is established as:

alpha of reflection coefficient corresponding to 0V and 2V in the above formula₀And alpha₁The relationship of (1);

step 3, repeating step 2 and repeating T in step 2₁The bias voltage of the intelligent reflection surface 4 is constantly set to [0V, 30V ] during the period]The bias voltage values of different voltages are shown in FIG. 3, and the reflection coefficients and alpha corresponding to different voltages are obtained₀The relationship of (1);

step 4, optionally, traversing the carrier signal frequency f_cRepeating the steps 1, 2 and 3 to obtain different signal frequencies f_cThe corresponding reflection coefficient versus bias voltage.

FIG. 3 is a graph comparing the results of the first and second measurements with the theoretical results. Wherein three identifiers "□", "x" and "o" are respectively the theoretical reflection phase, embodiment N_R＝3，N₀Measurement of reflection phase at 20 hours and example two N_R＝1，N₀The reflection phase is measured as three curves at 1. As shown in fig. 3, the measured reflection phase of the first embodiment substantially coincides with the theoretical reflection phase. The measured reflection phase of the second embodiment has a certain deviation from the reference reflection phase.

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.