System and method for evaluating communication quality in a reverberation room

Abstract

The present application discloses a system for evaluating the communication quality in a reverberation chamber, wherein an instrument control device controls a first stirring paddle and a second stirring paddle placed in the reverberation chamber to rotate their respective paddles according to a set step amplitude; after each rotation of the paddle, the signal source generating device is controlled to generate a measurement signal; the signal source generating device generates a measurement signal under the control of the instrument control device; and the measurement signal is sent through the transmitting antenna; a signal analyzer obtains an actual signal received by the receiving antenna; and based on the obtained measurement signal and the actual signal, the communication quality in the reverberation chamber corresponding to each rotation of the paddle under the current amount of absorbing materials is measured. Thus, the communication quality in the reverberation chamber is measured.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a system and method for evaluating communication quality in a reverberation room. Background Art

[0002] The wireless channel has a significant impact on the communication quality of the wireless communication system. In order to improve the communication performance of the communication system in a complex electromagnetic environment, it is necessary to design the communication system in a targeted manner according to the propagation characteristics of the wireless channel. There are many factors that affect the communication quality of the wireless channel, among which the multipath effect is one of the most important factors. In wireless communication systems, the root mean square delay spread (hereinafter referred to as delay spread), a statistical parameter of the power delay spectrum, is usually used to quantitatively describe the strength of the multipath effect. In order to ensure the communication quality of the wireless communication system under the fading channel, it is necessary to measure and evaluate the communication performance of the communication system under the fading channel. Traditionally, there are two methods for testing the channel fading resistance performance of the communication system, namely, testing in real scenarios and testing with wires connected to the RF port. Due to the randomness of real wireless communication scenarios, the schemes tested in real scenarios have natural disadvantages such as poor repeatability and unstable measurement results. Although the wire connection method uses a channel simulator, this method can only test the performance of the RF module and cannot reflect the influence of the antenna. Therefore, how to test the channel fading resistance performance of the communication system is a crucial topic. Summary of the invention

[0003] The embodiments of the present application provide a system and method for evaluating the communication quality in a reverberation room, which are used to measure the communication quality in the reverberation room.

[0004] On the one hand, an embodiment of the present application provides a system for evaluating the communication quality in a reverberation chamber, comprising an instrument control device, a signal source generating device, a signal analyzer, a transmitting antenna, and a receiving antenna, wherein the transmitting antenna and the receiving antenna are located in the reverberation chamber, and the reverberation chamber is provided with an absorbing material; wherein:

[0005] The instrument control device is used to control the first stirring paddle and the second stirring paddle placed in the reverberation chamber to rotate their respective blades according to the set step amplitude; and after each rotation of the blade, control the signal source generating device to generate a measurement signal;

[0006] The signal source generating device is used to generate a measurement signal under the control of the instrument control device; and transmit the measurement signal through the transmitting antenna;

[0007] The signal analyzer is used to obtain the actual signal received by the receiving antenna; and based on the measurement signal and the actual signal, measure the communication quality in the reverberation chamber corresponding to each rotation of the blade under the current amount of absorbing material.

[0008] On the other hand, an embodiment of the present application further provides a method for evaluating communication quality in a reverberation chamber, which is applied to an instrument control device, wherein the reverberation chamber is provided with an absorbing material, and the reverberation chamber is also provided with a transmitting antenna and a receiving antenna; the method comprises:

[0009] Controlling a first stirring paddle and a second stirring paddle placed in the reverberation chamber to rotate their respective blades according to a set step amplitude;

[0010] After each rotation of the blade, the signal source generating device is controlled to generate a measurement signal, so that the measurement signal is sent through the transmitting antenna connected to the signal source generating device, so that the signal analyzer receives the actual signal through the receiving antenna, and based on the measurement signal and the actual signal, the communication quality in the reverberation chamber corresponding to each rotation of the blade under the current amount of absorbing material is measured.

[0011] Beneficial effects of this application:

[0012] In implementing the above-mentioned communication quality measurement method in the reverberation chamber, a signal source generating device, a signal analyzer and an instrument control device are arranged outside the reverberation chamber, and a transmitting antenna and a receiving antenna are arranged in the reverberation chamber. Then, under the current amount of absorbing materials, after the instrument control device drives the blades of the first stirring paddle and the second stirring paddle in the reverberation chamber to rotate according to the step amplitude, the instrument control device drives the signal source generating device to generate a measurement signal, and then transmits the measurement signal to the reverberation chamber through the transmitting antenna connected to the signal source generating device, so that the actual signal is received by the receiving antenna in the reverberation chamber and sent to the signal analyzer connected thereto, so that the signal analyzer measures the communication quality in the reverberation chamber after the blades are rotated this time under the current amount of absorbing materials according to the acquired measurement signal and actual signal, thereby realizing the measurement of the communication quality in the reverberation chamber.

[0013] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0015] Figure 1 A schematic diagram of the structure of a reverberation chamber provided in an embodiment of the present application;

[0016] Figure 2A schematic diagram of the structure of a system for evaluating communication quality in a reverberation room provided in an embodiment of the present application;

[0017] Figure 3 A flowchart of a method for evaluating communication quality in a reverberation room provided in an embodiment of the present application;

[0018] Figure 4 A schematic diagram of the physical meaning of the error vector magnitude provided in an embodiment of the present application;

[0019] Figure 5 A schematic diagram of the structure of another system for evaluating the communication quality in a reverberation room provided in an embodiment of the present application;

[0020] Figure 6 A flowchart of another method for evaluating communication quality in a reverberation room provided in an embodiment of the present application;

[0021] Figure 7a A schematic diagram of the relationship between the blade position and the EVM under various amounts of absorbing materials provided in an embodiment of the present application;

[0022] Figure 7b A schematic diagram of the relationship between the position of the blades and the PL under various quantities of absorbing materials provided in the embodiments of the present application;

[0023] Figure 7c A schematic diagram showing the relationship between the position of the blades under various quantities of absorbing materials and the delay spread RMS DelaySpread provided in the embodiments of the present application;

[0024] Figure 8a A schematic diagram showing the relationship between EVM and PL at each blade position under two pieces of absorbing materials provided in an embodiment of the present application;

[0025] Figure 8b A schematic diagram of the correlation between EVM and PL under two pieces of absorbing materials provided in an embodiment of the present application;

[0026] Fig. 9 A flow chart of a method for evaluating communication quality in a reverberation room implemented by an instrument control device side provided in an embodiment of the present application;

[0027] Fig.10 A flowchart of another method for evaluating communication quality in a reverberation room implemented on the instrument control device side provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The embodiments of the present application provide a system and method for evaluating the communication quality in a reverberation chamber, which are used to measure the communication quality in the reverberation chamber.

[0029] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily. In addition, although the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in an order different from that here.

[0030] The terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the term "comprising" and any variation thereof are intended to cover non-exclusive protection. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0031] After studying and analyzing the method of using a reverberation chamber to simulate a fading channel and testing the communication quality of a communication product under a fading channel, the inventor found that most of the communication quality evaluation methods before the present application analyzed the channel characteristics in the reverberation chamber, or studied how to test the communication quality of certain specific communication products in the reverberation chamber. These methods study the test results of the communication products, and the demodulation, equalization and error correction algorithms developed by the manufacturer are solidified in the communication products. In this way, the measured communication quality is not only related to the reverberation chamber, but also to the demodulation and equalization algorithms of these products themselves. The results reflect the communication quality of the communication product in the reverberation chamber, rather than the communication quality of the reverberation chamber itself. In view of this, the present application provides a system for evaluating the communication quality in a reverberation chamber, including an instrument control device, a signal source generating device and a signal analyzer respectively connected to the instrument control device; the signal source generating device is connected to a transmitting antenna, the signal analyzer is connected to a receiving antenna, and the transmitting antenna and the receiving antenna are located in the reverberation chamber; the reverberation chamber includes a first stirring paddle, a second stirring paddle and an absorbing material, the first stirring paddle and the second stirring paddle are respectively connected to the instrument control device, and the first stirring paddle and the second stirring paddle respectively include a plurality of blades. On this basis, the instrument control device controls the first stirring paddle and the second stirring paddle to rotate their respective blades according to a set step amplitude; after each rotation of the blade, the signal source generating device is controlled to generate a measurement signal and send the measurement signal through the transmitting antenna, so that the measurement signal is transmitted in the reverberation chamber, so that the signal analyzer receives the actual signal using the receiving antenna, and measures the communication quality in the reverberation chamber corresponding to each rotation of the blade under the current number of absorbing materials according to the acquired measurement signal and the actual signal. This achieves the measurement of the communication quality in the reverberation room, rather than the measurement of the communication quality of the communication product in the reverberation room as in the prior art.

[0032] Before introducing the evaluation system for communication quality in a reverberation room provided by the present application, the reverberation room provided by the present application is introduced. Figure 1 As shown, the reverberation chamber includes a first stirring paddle, a second stirring paddle and a wave-absorbing material. The first stirring paddle and the second stirring paddle are respectively connected to the instrument control device. The first stirring paddle and the second stirring paddle respectively include a plurality of blades.

[0033] Specifically, the cavity of the reverberation chamber is a metal cavity, the characteristics of which are not easy to change, and the position of the blades and the amount of absorbing materials are two key adjustable factors that affect the electromagnetic characteristics of the reverberation chamber. From the perspective of radio wave propagation, changes in the blades and absorbing materials essentially affect the channel characteristics in the reverberation chamber, and changes in the channel characteristics will ultimately affect the communication quality in the reverberation chamber. Based on this principle, the present application also measures the channel characteristics in the reverberation chamber and conducts a joint analysis together with the communication quality. In order to analyze the specific impact of the channel characteristics on the communication quality.

[0034] Optionally, the net size of the internal cavity of the reverberation chamber may be, but is not limited to, 6.43m (length) * 5.09m (width) * 5.75m (height), etc. In order to analyze the influence of the blade positions of the first stirring paddle and the second stirring paddle on the communication quality in the reverberation chamber, the first stirring paddle and the second stirring paddle may be placed respectively in set directions, so that the first stirring paddle and the second stirring paddle can change the electromagnetic environment in the reverberation chamber when the blades are rotated. For example, the angle between the placed first stirring paddle and the second stirring paddle satisfies the set angle relationship, etc. Optionally, the first stirring paddle is placed horizontally in the reverberation chamber, and the second stirring paddle is placed vertically in the reverberation chamber, please also refer to Figure 1 Of course, the first stirring paddle can be placed obliquely in the reverberation chamber, and the second stirring paddle can also be placed obliquely, etc., in order to meet the above-mentioned set angle relationship.

[0035] It should be noted that Figure 1 This is only an example and does not constitute a limitation on the positions of the first stirring paddle and the second stirring paddle, nor does it constitute a limitation on the placement positions of the transmitting antenna, the receiving antenna and the absorbing material.

[0036] In addition, the blades in the first stirring paddle and the second stirring paddle can rotate synchronously according to a preset step amplitude, for example, the step amplitude can be but is not limited to 3.6 degrees, that is, one rotation requires 100 rotations, that is, the blade rotates 100 times to make exactly one rotation. In this way, the communication quality and channel characteristics in the reverberation chamber are measured at each rotation angle of the blade.

[0037] For the convenience of description, the following description is given by taking an example in which the first stirring paddle is placed horizontally, the second stirring paddle is placed vertically, and the step amplitude is 3.6 degrees.

[0038] Optionally, the amount of absorbing material in the reverberation chamber is adjustable, and the amount of absorbing material in the reverberation chamber can be adjusted according to actual conditions. The size of the absorbing material can be, but is not limited to, composed of 81 vertebrae, and the 81 vertebrae form a 9*9 vertebra array; and the bottom surface of each vertebra is a square of a set length, and the set length can be, but is not limited to, 6.8 cm; the vertebral height of the vertebrae can be, but is not limited to, 17.8 cm.

[0039] By providing the above reverberation chamber, preparation is made for the subsequent measurement of the communication quality in the reverberation chamber and the evaluation of the influence of channel parameters on the communication quality in the reverberation chamber.

[0040] Next, the evaluation system for communication quality in a reverberation room provided by the present application is introduced.

[0041] In order to complete the measurement of the communication quality in the reverberation room, the embodiment of the present application provides an evaluation system for the communication quality in the reverberation room, please refer to Figure 2 As shown, the system includes an instrument control device, a signal source generating device, a signal analyzer, a transmitting antenna, and a receiving antenna. The above system is used to measure the communication quality in the reverberation room. The system composed of the above equipment can also be called a reverberation room communication quality measurement system. For the structure of the reverberation room, please refer to Figure 1 As shown; the instrument control device is connected to the signal source generating device and the signal analyzer respectively; the signal source generating device is connected to the transmitting antenna, and the signal analyzer is connected to the receiving antenna; and the transmitting antenna and the receiving antenna are located in the reverberation chamber, wherein: the interaction flow chart between the instrument control device, the signal source generating device and the signal analyzer can be referred to Figure 3 As shown, the following steps may be included:

[0042] S301, the instrument control device controls the first stirring paddle and the second stirring paddle to rotate their respective blades according to the set step amplitude; and after each rotation of the blade, controls the signal source generating device to generate a measurement signal.

[0043] In this step, the amount of absorbing materials in the reverberation chamber is variable. To better understand this embodiment, the amount of absorbing materials in the reverberation chamber is adjusted from 0 to 4 as an example. After each adjustment of the amount of absorbing materials in the reverberation chamber, the instrument control device controls the blades of the first stirring paddle and the second stirring paddle to rotate according to the step amplitude under the current amount of absorbing materials, and after rotating the blades once, a signal generation instruction is sent to the signal source generating device.

[0044] S302: The signal source generating device generates a measurement signal under the control of the instrument control device; and sends the measurement signal through the transmitting antenna.

[0045] In this step, after receiving the signal generation instruction, the signal source generating device can generate a measurement signal, and then send the measurement signal through the transmitting antenna, and the transmitting antenna is located inside the reverberation chamber, so that the measurement signal can be transmitted in the reverberation chamber. Since the reverberation chamber is provided with a first stirring paddle, a second stirring paddle and a plurality of absorbing materials, the absorbing materials will absorb the energy in the reverberation chamber, and the rotating blades will affect the electromagnetic environment in the reverberation chamber, thereby causing the measurement signal to be interfered with or lose energy in the reverberation chamber. For example, when the blades rotate to different angles, the multipath interference generated in the reverberation chamber is different, which leads to different transmission quality of the signal in the reverberation chamber. The reverberation chamber also includes a receiving antenna for capturing signals. Based on the above reasons, the signal received by the receiving antenna in the reverberation chamber will be different from the measurement signal actually generated by the signal source generating device. For the convenience of description, the signal received by the receiving antenna is recorded as the actual signal in this application.

[0046] Optionally, the signal source generating device may be, but is not limited to, a vector signal source, etc. In one embodiment of the present application, when the signal source generating device is a vector signal source, the vector signal source may emit a QPSK digital modulation signal with a carrier frequency of 5 GHZ and a symbol rate of 15 ks / s, i.e., a measurement signal (the carrier frequency and symbol rate selected in this embodiment may be selected according to circumstances and do not constitute a limitation of the present invention). In addition, the above-mentioned transmitting antenna may be, but is not limited to, a directional antenna, and the signal transmission direction of the directional antenna points to a set direction outside the receiving antenna. For example, the directional antenna points to a corner above the reverberation chamber, and on this basis, the modulated signal is emitted by the directional antenna, thereby avoiding forming a direct path with the receiving antenna, and to a certain extent, the communication quality in the reverberation chamber can be measured more accurately.

[0047] S303, the signal analyzer obtains the actual signal received by the receiving antenna; and measures the communication quality in the reverberation chamber corresponding to each rotation of the blades under the current amount of absorbing materials according to the measurement signal and the actual signal.

[0048] In this step, the receiving antenna is connected to the signal analyzer so that the signal analyzer can obtain the actual signal received by the receiving antenna; then the signal analyzer can measure the communication quality in the reverberation chamber corresponding to the rotation of the blades under the current amount of absorbing material based on the obtained measurement signal and the actual signal.

[0049] It should be noted that the signal source generating device is connected to the signal analyzer, for example, the signal source generating device is frequency-lockedly connected to the signal analyzer, so that after the signal source generating device generates a measurement signal, the measurement signal is directly sent to the signal analyzer through the cable; thereby, the signal analyzer can obtain the measurement signal generated by the signal source generating device. Alternatively, the measurement signal can also be locally generated by the signal analyzer according to the measurement signal generation logic of the signal source generating device; furthermore, the measurement signal can be an ideal signal pre-set in the signal source generating device and the signal analyzer respectively. Furthermore, the signal source generating device can also send the measurement signal to the instrument control device, and then the instrument control device forwards the measurement signal to the signal analyzer, and so on. The manner in which the signal analyzer obtains the measurement signal is not limited in this application.

[0050] Optionally, the signal analyzer may be, but is not limited to, a vector signal analyzer, corresponding to the signal source generating device. Accordingly, the above-mentioned receiving antenna may be, but is not limited to, an omnidirectional biconical antenna. On this basis, the actual signal is received by the vector signal analyzer through an omnidirectional biconical antenna. Then the vector signal analyzer can measure the communication quality in the reverberation chamber based on the measured signal and the actual signal received, and the communication quality obtained is the communication quality in the reverberation chamber after the blades are rotated this time under the current amount of absorbing materials.

[0051] After this, the blades of the first stirring paddle and the second stirring paddle can be rotated according to the step amplitude and then the operation can be performed again. Figure 3 The process shown in FIG. 1 is repeated until the blades of the first stirring paddle and the second stirring paddle are rotated one circle with the current amount of absorbing materials, and the communication quality after each rotation is measured. At this time, the amount of absorbing materials in the reverberation chamber can be adjusted, and then the process shown in FIG. 1 is repeated again. Figure 3 For example, adjust the number of absorbers from 0 to 4, and then follow Figure 3 The process shown is to perform the communication quality in the reverberation chamber after each rotation of the blade with various amounts of absorbing materials.

[0052] Optionally, based on any of the above embodiments, in this embodiment, the communication quality in the reverberation room can be expressed by Error Vector Magnitude (EVM), and the calculation formula of EVM is:

[0053]

[0054] Where T(I,Q) is the position of the actual signal on the IQ vector diagram, R(I0,Q0) is the position of the measured signal on the IQ vector diagram, and Figure 4As shown; EVM is the relative distance between the actual signal and the measured signal. After obtaining the measured signal and the measured signal, the EVM in the reverberation chamber can be determined by the above formula.

[0055] It is worth noting that the measured signal can be understood as an ideal signal. The larger the EVM, the farther the actual signal deviates from the measured signal, and accordingly, the worse the communication quality.

[0056] On this basis, the signal source generating device and the signal analyzer can measure the communication quality in the reverberation chamber according to the following process: the signal source generating device generates a preset number of measurement signals after each rotation of the blade, and sends each measurement signal through the transmitting antenna. The signal analyzer calculates the error vector amplitude of the measurement signal in the reverberation chamber under the conditions of a given number of absorbing materials and a given blade rotation angle based on each measurement signal obtained and the corresponding actual signal received; based on each calculated error vector amplitude, the error vector amplitude in the reverberation chamber under the number of absorbing materials is determined.

[0057] Specifically, the signal source generating device can send a preset number of measurement signals under the current number of absorbing materials, each time each blade of the first stirring paddle and the second stirring paddle is rotated, under the rotation angle condition after each blade is rotated, and accordingly, the signal analyzer will receive the corresponding number of actual signals and calculate the preset number of EVMs respectively; then the average value of the preset number of EVMs is determined as the EVM in the reverberation chamber under the number of absorbing materials. Optionally, the above-mentioned set number can be but is not limited to 1000.

[0058] Optionally, before implementing the communication quality measurement process in the reverberation chamber, in this embodiment, the signal source generating device and the crystal oscillator of the signal analyzer are connected to achieve frequency synchronization between the two devices, thereby ensuring the accuracy of the communication quality measurement results.

[0059] Optionally, before measuring the communication quality in the reverberation chamber, the signal source generating device and the signal analyzer can be directly connected by a cable to measure the "noise floor" between the signal source generating device and the signal analyzer. For example, a cable is used to directly connect the signal source generating device and the signal analyzer. For example, when the symbol rate is 15ks / s, the EVM0 between the two devices under direct wire connection is 0.25%. This measurement result is much smaller than the EVM obtained after the signal passes through the reverberation chamber. Therefore, it can be considered that the measurement results in the reverberation chamber can accurately reflect the impact of the poor channel of the reverberation chamber on the signal, and then analyze the impact of various factors in the reverberation chamber on the communication quality.

[0060] In implementing the above-mentioned communication quality measurement method in the reverberation chamber, a signal source generating device, a signal analyzer and an instrument control device are arranged outside the reverberation chamber, and a transmitting antenna and a receiving antenna are arranged in the reverberation chamber. Then, under the current amount of absorbing materials, after the instrument control device drives the blades of the horizontally placed first stirring paddle and the vertically placed second stirring paddle to rotate according to the step amplitude, the instrument control device drives the signal source generating device to generate a measurement signal, and then transmits the measurement signal to the reverberation chamber through the transmitting antenna connected to the signal source generating device, so that the signal is received by the receiving antenna in the reverberation chamber, so that the signal analyzer measures the communication quality in the reverberation chamber after the blades are rotated this time under the current amount of absorbing materials according to the acquired measurement signal and the actual signal actually received, thereby realizing the measurement of the communication quality in the reverberation chamber.

[0061] Optionally, based on any of the above embodiments, this embodiment further provides another evaluation system for communication quality in a reverberation room, referring to Figure 5 As shown, the system includes an instrument control device, a network analyzer, a transmitting antenna, and a receiving antenna. The system is also called a channel measurement system in a reverberation chamber (channel characteristic measurement system). The instrument control device is connected to the network analyzer, and the network analyzer is connected to the transmitting antenna and the receiving antenna respectively; and the transmitting antenna and the receiving antenna are respectively arranged in the reverberation chamber.

[0062] It should be noted that in actual applications, Figure 2 and Figure 5 When the system is shown, the instrument control device can be simultaneously Figure 2 and Figure 5 The corresponding devices are connected in the connection method shown, and then the communication quality in the reverberation room and the channel measurement results in the reverberation room are measured simultaneously.

[0063] Specifically, instrument control equipment and network analyzers can be Figure 6 The process shown implements a method for evaluating the communication quality in a reverberation room, including the following steps:

[0064] S601. After each rotation of the blades, the instrument control device sends a channel measurement instruction to the network analyzer under the current amount of absorbing materials.

[0065] In this embodiment, the amount of absorbing materials in the reverberation chamber is also adjustable. For example, the amount of absorbing materials can also be adjusted from 0 to 4. Then, after each adjustment of the amount of absorbing materials in the reverberation chamber, the instrument control device rotates the blades of the first stirring paddle and the second stirring paddle according to the step amplitude. After each rotation of the blades, a channel measurement instruction is sent to the network analyzer.

[0066] S602. After receiving the channel measurement instruction, the network analyzer performs a frequency sweep measurement process of a set frequency band and a set number of frequency points in the reverberation chamber, and calculates the channel evaluation parameter value of the wireless channel formed between the transmitting antenna and the receiving antenna in the reverberation chamber after each rotation of the blades under the current number of absorbing materials.

[0067] In this step, after receiving the above channel measurement instruction, the network analyzer will scan and process the wireless channel formed between the transmitting antenna and the receiving antenna in the reverberation chamber to calculate the channel evaluation result of the wireless channel in the reverberation chamber corresponding to each rotation of the blade under the current number of absorbing materials.

[0068] For example, the set frequency band may be, but is not limited to, 4.9 GHz to 5.1 GHz, and the set number of frequency points may be, but is not limited to, 1024.

[0069] Optionally, the channel evaluation parameters may include, but are not limited to, path loss and delay spread, etc. On this basis, the network analyzer may perform step S602 according to the following process: in a set frequency band, each set frequency point number is measured using a channel transmission function to obtain the path loss of the wireless channel under a given number of absorbing materials and a given blade rotation angle; and the power delay spectrum of the wireless channel is calculated according to the channel transmission function; the power delay spectrum is processed using the parameter extraction algorithm to obtain the delay spread value of the wireless channel under a given number of absorbing materials and a given rotation angle.

[0070] For example, when the network analyzer performs channel scanning, it can perform a frequency sweep measurement with 1024 points in any of the above frequency bands, so as to obtain the amplitude frequency response and phase frequency response of the wireless channel. In the field of wireless communication, this frequency response containing amplitude and phase information is also called the channel transfer function (CTF). From the channel transfer function, the path loss (PL) of the wireless channel formed between the transmitting antenna and the receiving antenna is obtained by the following formula:

[0071]

[0072] Among them, the above PL is the path loss of the wireless channel, N f is the number of frequency points to be scanned, f is the frequency used in the set frequency band, H(f k ) is the channel transfer function, and is the calibrated channel transfer function. The calibration method can adopt the currently provided method, and this application does not limit this.

[0073] Furthermore, the channel transfer function may be subjected to inverse Fourier transform processing, and the square of the absolute value may be taken to obtain the power delay profile (PDP) of the wireless channel, referring to the following formula:

[0074] PDP(τ)=|IFFT[H(f)]| 2

[0075] The above PDP(τ) refers to the power delay profile of the wireless channel, and τ is the delay.

[0076] On this basis, the root mean square delay spread (Root-Mean-Square Delay Spread) is calculated by the power delay spectrum and parameter extraction algorithm, referring to the following formula:

[0077]

[0078] Among them, τ rms is the RMS delay spread, N is the number of paths generated in the wireless channel; τ j is the delay of the jth path in the wireless channel, PDP(τ j ) is the power delay spectrum of the jth path in the wireless channel.

[0079] It should be noted that when calculating the channel evaluation parameter value, what is calculated is the channel evaluation parameter value at the rotation angle of the blade after each rotation of the blade under the current absorbing material, that is, it is necessary to calculate the channel evaluation parameter value of the wireless channel under each rotation angle condition of the blade; after measuring the above channel evaluation parameter value after one rotation, adjust the amount of absorbing material in the reverberation chamber, and then repeat the above process.

[0080] S603. The instrument control device evaluates the correlation between the channel evaluation parameter value and the communication quality in the reverberation chamber according to the communication quality of the reverberation chamber and the channel evaluation parameter value of the wireless channel in the reverberation chamber measured under the condition of pre-setting different amounts of absorbing materials in the reverberation chamber.

[0081] In this step, the error vector magnitude EVM, path loss PL and delay spread τ of the reverberation chamber under various conditions of various numbers of absorbing materials and blade rotation angles are calculated. rms After that, we can analyze the relationship between the error vector magnitude EVM, path loss PL and delay spread (RMS Delay Spread) and the paddle position (Stepped Paddle Position) under different amounts of absorbing materials. The paddle position can be understood as the number of rotations of the paddle. Taking the above step amplitude of 3.6 degrees as an example, the first stirring paddle and the second stirring paddle need to rotate 100 times for one circle. Figure 7a to Figure 7cThe relationship between the error vector magnitude (EVM), path loss (PL), and delay spread (RMS Delay Spread) and the stepped paddle position (Stepped Paddle Position) obtained by analyzing the blade rotation 100 times under different amounts of absorbing materials is shown in the figure. Figure 7a to Figure 7c As shown, from Figure 7a and Figure 7b It can be seen that the blade position (the number of blade rotations) has a greater impact on EVM and PL. EVM and PL change dramatically with the change of the blade position (the number of blade rotations), indicating that the blade position (the number of blade rotations) has a significant impact on the two parameters of EVM and PL. Figure 7c It can be seen that the blade position (number of rotations of the blade) has little effect on the delay spread.

[0082] Furthermore, we can analyze the relationship between the two parameters, EVM and PL, which change dramatically with the blade position (number of blade rotations) under different amounts of absorbing materials, and conclude that there is a strong correlation between EVM and PL. Take the example of loading two pieces of absorbing materials in the reverberation chamber to illustrate. Figure 8a and Figure 8b The correlation between EVM and PL under two absorbing materials is given. Figure 8a and Figure 8b The correlation between EVM and PV measured with 100 blade rotations under two absorbers is described in Figure 2. Figure 8a The relationship between EVM and PL at each blade position (number of blade rotations) under the two absorbing materials is given. It can be concluded that at the blade position with a larger PL (number of blade rotations, such as the 6th and 94th rotations of the blades), the communication quality (measured by EVM) also deteriorates significantly. Figure 8b The correlation between EVM and PL under two absorbing materials is given, and it can be seen that there is an obvious positive correlation between EVM and PL.

[0083] Optionally, when the communication quality includes an error vector magnitude and the channel evaluation parameter includes a path loss, step S603 may be performed by the following process: based on the error vector magnitude and the path loss measured under the conditions of each given amount of absorbing material and each rotation angle of a given blade, a correlation coefficient between the path loss and the error vector magnitude is calculated. The above correlation coefficient may characterize the influence of the above channel evaluation parameter on the above communication quality.

[0084] Specifically, the correlation between EVM and PL under various amounts of absorbing materials is quantitatively characterized by the above method and represented by the correlation coefficient. The calculation formula is as follows:

[0085]

[0086] Wherein, ρ is the correlation coefficient between the calculated path loss and the error vector magnitude under the current number of absorbing materials, M is the number of rotations of the blade, EVM(i) is the error vector magnitude measured at the i-th rotation of the blade under the current number of absorbing materials, is the mean value of the error vector amplitude obtained by rotating the blade M times under the current number of absorbing materials, PL(i) is the path loss measured by the i-th rotation of the blade under the current number of absorbing materials, is the average path loss obtained by rotating the blade M times with the current amount of absorbing materials.

[0087] Experiments show that when the number of absorbing materials placed in the reverberation chamber changes from 0 to 4, the correlation coefficients between EVM and PL are 0.637, 0.713, 0.738, 0.763, and 0.808, respectively. It can be further seen that under different numbers of absorbing materials, there is a strong correlation between EVM and PL.

[0088] Optionally, based on any of the above embodiments, this embodiment further provides the following method for evaluating the communication quality in a reverberation chamber: calculating the mean, standard deviation and relative standard deviation of the error vector amplitude in the reverberation chamber under each given number of absorbing materials; respectively calculating the mean, standard deviation and relative standard deviation of the path loss of the wireless channel and the delay spread under each given number of absorbing materials.

[0089] Specifically, the mean values ​​of the error vector magnitude, path loss, and delay spread may be calculated respectively according to the following formulas:

[0090]

[0091] Accordingly, the standard deviation and relative standard deviation of the error vector magnitude, path loss and delay spread can be calculated according to the following two formulas:

[0092]

[0093]

[0094] Where X represents any parameter among error vector magnitude, path loss and delay spread, M is the number of rotations of the blade, m is the number of absorbing materials in the reverberation chamber, i represents the i-th rotation of the blade, and E X,m represents the average value of parameter X under m absorbing materials; S X,m represents the standard deviation of parameter X under m absorbing materials; RS X,m Represents the relative standard deviation of parameter X under m absorbing materials.

[0095] In order to better understand the influence of the channel evaluation parameters on the communication quality in the reverberation room in this embodiment, the statistical characteristics of the error vector amplitude, path loss and delay spread under different amounts of absorbing materials are given in Table 1:

[0096] Table 1

[0097]

[0098] The relative standard deviation in Table 1 reflects the relative fluctuation of each parameter at different blade positions (number of blade rotations). Figure 7a The observed results are consistent, that is, PL and EVM change dramatically with the blade position (number of blade rotations), while the delay spread changes relatively little with the blade position (number of blade rotations). Moreover, the mean values ​​of the parameters in Table 1 reflect the influence of the number of absorbing materials. It can be seen that in addition to the monotonically decreasing delay spread with the increase of the number of absorbing materials, the mean values ​​of PL and EVM also change monotonically with the increase of the number of absorbing materials. This shows that although PL and EVM fluctuate dramatically with the blade position (number of blade rotations), their averaged statistical characteristics are regular. As a test environment, the "channel" after surface averaging has better stability and consistency. The reason why the path loss increases monotonically with the increase of absorbing materials is that the more absorbing materials there are in the reverberation chamber, the more energy the signal transmitted by the transmitting antenna into the reverberation chamber is absorbed by the absorbing materials, so the energy that the receiving antenna can receive will be reduced, so the path loss will increase. The reason why the communication quality improves with the increase of the number of absorbing materials in the reverberation chamber is that the addition of absorbing materials reduces the delay spread in the reverberation chamber, thereby improving the communication quality.

[0099] So far, by implementing the method for measuring the communication quality in the reverberation chamber provided by the present application, not only the communication quality in the reverberation chamber is measured; and based on this method, supplemented by the channel characteristic (channel evaluation parameter) measurement method, two key factors affecting the communication quality in the reverberation chamber are analyzed. First, the position of the blades will have a significant impact on the communication quality. From the perspective of the radio wave propagation mechanism, the blade position (the number of rotations of the blades) mainly affects the path loss of the channel, but has little effect on the delay spread characteristics. The strong correlation between the communication quality and the path loss at different blade positions (rotation angles of the blades) indicates that the change in communication quality at different blade positions (number of rotations of the blades) is mainly caused by the change in path loss. The absorbing material mainly changes the delay spread characteristics of the channel, but will eventually affect the communication quality in the reverberation chamber.

[0100] In addition, the throughput rate, receiving sensitivity and other tests conducted in the reverberation chamber are essentially to measure the performance of communication products in resisting channel fading. Channel fading can be further divided into path loss and delay spread. By implementing the above method provided by the present application, it is possible to design and optimize communication performance tests in the reverberation chamber, especially to provide an important technical basis and reference for the targeted design of communication performance tests of communication products under different fading.

[0101] Based on the same inventive concept, the present application also provides a method for evaluating the communication quality in a reverberation chamber, which is applied to an instrument control device, wherein the instrument control device is connected to a signal source generating device and a signal analyzer respectively; the signal source generating device is connected to a transmitting antenna, the signal analyzer is connected to a receiving antenna, and the transmitting antenna and the receiving antenna are located in the reverberation chamber, please refer to Figure 2 The system structure diagram shown in FIG. 1; the reverberation chamber comprises a horizontally placed first stirring paddle, a vertically placed second stirring paddle and an absorbing material, wherein the first stirring paddle and the second stirring paddle are respectively connected to the instrument control device, and the first stirring paddle and the second stirring paddle respectively comprise a plurality of blades, please refer to FIG. Figure 1 The reverberation chamber shown; on this basis, the instrument control device may include when implementing the above method Fig. 9 Steps shown:

[0102] S901 , controlling the first stirring paddle and the second stirring paddle to rotate their respective blades according to a set step amplitude.

[0103] S902. After each rotation of the blade, control the signal source generating device to generate a measurement signal, so as to send the measurement signal through the transmitting antenna connected to the signal source generating device, so that the signal analyzer receives the actual signal through the receiving antenna, and measures the communication quality in the reverberation chamber corresponding to each rotation of the blade under the current amount of absorbing material based on the measurement signal and the actual signal.

[0104] It should be noted that the implementation of steps S901 to S902 can refer to Figure 2 The relevant description of the instrument control device in the process shown in the figure, in addition, please refer to the processing process of the signal analyzer in step S902 Figure 2 The relevant descriptions in the article will not be described in detail here.

[0105] Optionally, the method for evaluating the communication quality in a reverberation room provided in this embodiment can also be applied to Figure 5 In the system shown in FIG. 1 , that is, at this time, the instrument control device is also connected to a network analyzer, and the network analyzer is connected to a transmitting antenna and a receiving antenna respectively; on this basis, this embodiment also provides a method for evaluating communication quality by channel evaluation parameters in a reverberation room, which may include: Fig.10 Steps shown:

[0106] S1001. After each rotation of the blades, under the current number of absorbing materials, a channel measurement instruction is sent to the network analyzer, so that the network signal analyzer performs a sweep frequency measurement process of a set frequency band and a set number of frequency points in the reverberation chamber after receiving the channel measurement instruction, and calculates a channel evaluation parameter value of a wireless channel formed between the transmitting antenna and the receiving antenna in the corresponding reverberation chamber after each rotation of the blades under the current number of absorbing materials.

[0107] S1002. Evaluate the correlation between the channel evaluation parameter value and the communication quality in the reverberation chamber according to the communication quality of the reverberation chamber and the channel evaluation parameter value of the wireless channel in the reverberation chamber respectively measured under the condition that different amounts of absorbing materials are pre-set in the reverberation chamber.

[0108] It should be noted that the implementation of step S1001 and step S1002 can refer to Figure 6 In addition, for the processing of the network analyzer in step S1001, please refer to the relevant description of step S602. Each step is described in detail here.

[0109] Based on the above embodiments, the communication quality in this embodiment includes the error vector magnitude, and the channel assessment parameter includes the path loss. On this basis, step S1002 can be performed according to the following process: based on the error vector magnitude and path loss measured under the conditions of each given number of absorbing materials and each rotation angle of a given blade, the correlation coefficient between the path loss and the error vector magnitude is calculated.

[0110] For details on the implementation of the above process, please refer to Figure 6 The description of step S603 is not described in detail here.

[0111] Optionally, based on any of the above embodiments, the communication quality in this embodiment includes an error vector magnitude, and the channel evaluation parameters include path loss and delay spread; on this basis, this embodiment also provides the following method: calculating the mean, standard deviation and relative standard deviation of the error vector magnitude in the reverberation chamber under each given number of absorbing materials; and respectively calculating the mean, standard deviation and relative standard deviation of the path loss and the delay spread of the wireless channel under each given number of absorbing materials.

[0112] Specifically, the implementation of the above method can refer to the above instrument control equipment for the mean, standard deviation, relative standard deviation and Table 1 and the related description of Table 1, which will not be described in detail here.

[0113] By implementing the method for measuring the communication quality in the reverberation chamber provided by the present application, not only the communication quality in the reverberation chamber is measured; and based on this method, supplemented by the channel characteristic (channel evaluation parameter) measurement method, two key factors affecting the communication quality in the reverberation chamber are analyzed. First, the blade position (the number of rotations of the blade) will have a significant impact on the communication quality. From the perspective of the radio wave propagation mechanism, the blade position (the number of rotations of the blade) mainly affects the path loss of the channel, but has little effect on the delay spread characteristics. The strong correlation between the communication quality and the path loss at different blade positions (the number of rotations of the blade) indicates that the change in communication quality at different blade positions (the number of rotations of the blade) is mainly caused by the change in path loss. The absorbing material mainly changes the delay spread characteristics of the channel, but will eventually affect the communication quality in the reverberation chamber.

[0114] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0115] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0118] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0119] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A system for evaluating communication quality in a reverberation room, characterized in that: It includes an instrument control device, a signal source generating device, a signal analyzer, a transmitting antenna, and a receiving antenna. The transmitting antenna and the receiving antenna are located in a reverberation chamber, and the reverberation chamber is provided with absorbing materials; wherein: The instrument control device is used to control the first stirring paddle and the second stirring paddle placed in the reverberation chamber to rotate their respective blades according to the set step amplitude; and after each rotation of the blade, control the signal source generating device to generate a measurement signal; The signal source generating device is used to generate a measurement signal under the control of the instrument control device; and transmit the measurement signal through the transmitting antenna; The signal analyzer is used to obtain the actual signal received by the receiving antenna; and measure the communication quality in the reverberation chamber corresponding to each rotation of the blade under the current amount of absorbing material according to the measurement signal and the actual signal; The system further comprises a network analyzer connected to the instrument control device, and the network analyzer is connected to the transmitting antenna and the receiving antenna respectively, wherein: The instrument control device is further used to send a channel measurement instruction to the network analyzer at the current amount of absorbing material after each rotation of the blade; The network analyzer is used to perform a sweep frequency measurement process of a set frequency band and a set number of frequency points in the reverberation chamber after receiving the channel measurement instruction, and calculate the channel evaluation parameter value of the wireless channel formed between the transmitting antenna and the receiving antenna in the reverberation chamber corresponding to each rotation of the blades under the current number of absorbing materials; The instrument control device is further used to evaluate the correlation between the channel evaluation parameter value and the communication quality in the reverberation chamber according to the communication quality of the reverberation chamber and the channel evaluation parameter value of the wireless channel in the reverberation chamber respectively measured under the condition that different amounts of absorbing materials are pre-set in the reverberation chamber; The communication quality is characterized by error vector magnitude; The signal source generating device is specifically used to generate a preset number of measurement signals after each rotation of the blade, and send each measurement signal through the transmitting antenna; The signal analyzer is specifically used to calculate the error vector amplitude of the measurement signal in the reverberation chamber under the conditions of a given number of absorbing materials and a given blade rotation angle according to each measurement signal obtained and the corresponding actual signal received; based on each calculated error vector amplitude, determine the error vector amplitude in the reverberation chamber under the condition of the number of absorbing materials; The channel assessment parameters include path loss and delay spread; The network analyzer is specifically used to measure each set frequency point number under a set frequency band using a channel transfer function to obtain the path loss of the wireless channel under the conditions of a given number of absorbing materials and a given blade rotation angle; and calculate the power delay spectrum of the wireless channel according to the channel transfer function; and process the power delay spectrum using the parameter extraction algorithm to obtain the delay spread value of the wireless channel under the conditions of a given number of absorbing materials and a given blade rotation angle; The communication quality includes an error vector magnitude, and the channel assessment parameter includes a path loss; The instrument control device is specifically used to calculate the correlation coefficient between the path loss and the error vector magnitude based on the error vector magnitude and the path loss measured under the conditions of each given amount of absorbing material and each rotation angle of the given blade; The instrument control device is specifically used to calculate the correlation coefficient between the channel estimation parameter and the error vector magnitude according to the following formula based on the error vector magnitude and path loss measured under the conditions of the current number of absorbing materials in the reverberation chamber and the rotation angle of the blade: ρ is the correlation coefficient between the calculated path loss and the error vector magnitude under the current number of absorbing materials; M is the number of rotations of the blade; EVM(i) is the error vector magnitude measured at the i-th rotation of the blade under the current amount of absorbing material; is the mean value of the error vector amplitude obtained by rotating the blade M times under the current number of absorbing materials; PL(i) is the path loss measured for the i-th blade rotation under the current amount of absorbing materials; is the average path loss obtained by rotating the blade M times with the current amount of absorbing materials.

2. The system according to claim 1, characterized in that The communication quality includes error vector magnitude, and the channel assessment parameters include path loss and delay spread; The instrument control device is specifically used to calculate the mean, standard deviation and relative standard deviation of the error vector amplitude in the reverberation chamber under each given number of absorbing materials; and respectively calculate the mean, standard deviation and relative standard deviation of the path loss and the delay spread of the wireless channel under each given number of absorbing materials.

3. The system according to claim 1, characterized in that The first stirring paddle is horizontally disposed in the reverberation chamber, and the second stirring paddle is vertically disposed in the reverberation chamber.

4. The system according to claim 1, characterized in that The signal source generating device is frequency-lockedly connected to the signal analyzer; the signal analyzer obtains the measurement signal from the signal source generating device.

5. A method for evaluating communication quality in a reverberation room, characterized in that: Applied to instrument control equipment, the reverberation chamber is provided with absorbing materials, and the reverberation chamber is also provided with a transmitting antenna and a receiving antenna; the method comprises: Controlling a first stirring paddle and a second stirring paddle placed in the reverberation chamber to rotate their respective blades according to a set step amplitude; After each rotation of the blade, the signal source generating device is controlled to generate a measurement signal, so that the measurement signal is sent through the transmitting antenna connected to the signal source generating device, so that the signal analyzer receives the actual signal through the receiving antenna, and the communication quality in the corresponding reverberation chamber after each rotation of the blade under the current amount of absorbing material is measured according to the measurement signal and the actual signal; The method further comprises: After each rotation of the blades, under the current number of absorbing materials, a channel measurement instruction is sent to the network analyzer, so that after receiving the channel measurement instruction, the network analyzer performs a sweep frequency measurement process of a set frequency band and a set number of frequency points in the reverberation chamber, and calculates a channel evaluation parameter value of a wireless channel formed between the transmitting antenna and the receiving antenna in the corresponding reverberation chamber after each rotation of the blades under the current number of absorbing materials; According to the communication quality of the reverberation chamber and the channel evaluation parameter value of the wireless channel in the reverberation chamber respectively measured under the condition that different amounts of absorbing materials are pre-set in the reverberation chamber, evaluating the correlation between the channel evaluation parameter value in the reverberation chamber and the communication quality; The communication quality is characterized by an error vector amplitude; the error vector amplitude is determined by the signal analyzer according to the following method: according to each measurement signal obtained and the corresponding actual signal received, the error vector amplitude of the measurement signal in the reverberation chamber under the conditions of a given number of absorbing materials and a given blade rotation angle is calculated; based on each calculated error vector amplitude, the error vector amplitude in the reverberation chamber under the condition of the number of absorbing materials is determined; wherein each measurement signal is a preset number of measurement signals generated by the signal source generating device after each rotation of the blade, and is sent through the transmitting antenna; The channel assessment parameters include path loss and delay spread; the path loss is determined by the network analyzer according to the following method: in a set frequency band, each set frequency point number is measured using a channel transfer function to obtain the path loss of the wireless channel under the conditions of a given number of absorbing materials and a given blade rotation angle; the delay spread is determined by the network analyzer according to the following method: the power delay spectrum of the wireless channel is calculated according to the channel transfer function; the power delay spectrum is processed using the parameter extraction algorithm to obtain the delay spread value of the wireless channel under the conditions of a given number of absorbing materials and a given blade rotation angle; The communication quality includes an error vector magnitude, and the channel evaluation parameter includes a path loss; and evaluating the correlation between the channel evaluation parameter value in the reverberation chamber and the communication quality according to the communication quality of the reverberation chamber and the channel evaluation parameter value of the wireless channel in the reverberation chamber respectively measured under the condition that different amounts of absorbing materials are pre-set in the reverberation chamber, comprises: Calculating a correlation coefficient between the path loss and the error vector magnitude based on the error vector magnitude and the path loss measured under the conditions of each given number of absorbing materials and each rotation angle of the given blade, including: calculating a correlation coefficient between the channel evaluation parameter and the error vector magnitude based on the error vector magnitude and the path loss measured under the conditions of the current number of absorbing materials and the rotation angle of the blade in the reverberation chamber according to the following formula: ρ is the correlation coefficient between the calculated path loss and the error vector magnitude under the current number of absorbing materials; M is the number of rotations of the blade; EVM(i) is the error vector magnitude measured at the i-th rotation of the blade under the current amount of absorbing material; is the mean value of the error vector amplitude obtained by rotating the blade M times under the current number of absorbing materials; PL(i) is the path loss measured for the i-th blade rotation under the current amount of absorbing materials; is the average path loss obtained by rotating the blade M times with the current amount of absorbing materials.

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