System, method and test equipment for over-the-air testing of a radio device

Abstract

A system for OTA testing of a radio device, a method, and a test device. First, the inverse matrix of a spatial transmission matrix assigned to multiple subfrequency bands is applied between the test device and the radio device. Then, a desired test signal with a preset frequency band is frequency-band-divided into desired test signals assigned to the multiple subfrequency bands. Finally, the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands is applied to the desired test signals assigned to the multiple subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio device, and performing an OTA test of the radio device.This solves the problems of low isolation and low test accuracy that occur when using the Radiated Two-Stage (RTS) method to perform a test, which are caused by a high amplitude-phase mismatch in the desired test signal with the preset frequency band with a wider bandwidth.

Description

Technical area

[0001] The present invention relates to the field of communications testing, in particular to a system, method and test apparatus for over-the-air (OTA) testing of a radio device. Technical background

[0002] To increase data transmission rates, MIMO (multi-input, multi-output) technology is widely used in modern radio technologies. A MIMO radio has at least two receiver ports (connected to the receiving antenna) and / or at least two transmitter ports (connected to the transmitting antenna). The MIMO OTA test is a test method for the performance of an entire device with multiple antennas. It measures the received power of a radio by emulating the channel model and creating a complex electromagnetic environment in an anechoic chamber.

[0003] As in Fig. As shown in Figure 1, a base station has M transmit antennas, while a radio device as a terminal has N receive antennas. A signal is transmitted from the transmit port of the base station to the receive port of the radio device, traversing various paths, including direct paths and reflected paths. The basic parameters of a MIMO channel model include, among others, the power distribution, the angle of radiation (AoA), the angle of arrival (AoD), the delay, and the Doppler effect. These basic parameters are defined in detail in 3GPP, and the channel model h n,m (t) between the m-th transmitting port in the base station and the n-th receiving port in the terminal can be described as follows: hn,m(t)=∑l=1Le(j2πΦlt+ψl+(−j2πfτl))[Gn,DUTV(αl,AOA)Gn,DUTH(αl,AOA)]T×[χlV,VχlV,HχlH,VχlH,H] ×[Gm,BSH(βl,AOD)Gm,BSH(βl,AOD)] where l is one of the L subpaths, t is the time and f is the center frequency of the test; Ψl , Φ l and τ l represent the main phase, the Doppler effect and the delay of the l-th sub-path, respectively; Gn,DUTx and Gm,BSx ( x represents the antenna polarization) represent the antenna gain of the n-th receiving antenna of the terminal and the antenna gain of the m-th transmitting antenna of the base station, α l,AoA , β l,AoD , and χlx,y represent the AoA, the AoD and the path loss from the antenna polarization y to the antenna polarization x in the l-th sub-path, respectively.

[0004] In conventional MIMO tests, for example a 2×2 MIMO test as in Fig. As shown in Figure 2, an output port of the channel emulator and an antenna port of the wireless terminal are typically directly connected via a cable to integrate the wireless terminal's antenna directivity pattern into the channel emulator for calculation, and finally, the test signal is fed into the wireless terminal's antenna port via the cable to perform a MIMO power measurement of the wireless terminal. However, this test method causes two problems as follows: (1) In the wired way, the two antenna connections of the wireless terminal are very highly isolated from each other, but when the wireless terminal is in practical operation, the two antennas are only isolated from each other to a limited extent; (2) The influence of the inherent noise of the wireless device on the MIMO performance (i.e. desense in related technologies) cannot be taken into account in the test results.

[0005] In this context, the wireless device is in a different state during a wired measurement than during an OTA measurement of an entire device, and OTA measurement cannot be replaced by a power-based method. Furthermore, due to the widespread use of millimeter waves, many millimeter-wave antennas are installed directly on millimeter-wave modules (AiP), and the entire module lacks a wired interface, which also makes it impossible to conduct MIMO measurements in the millimeter-wave range using a wired method.

[0006] The MIMO OTA test methods in the 3GPP and CTIA standards include the Radiated Two-Stage (RTS) method and the Multi-Probe Anechoic Chamber (MPAC) method. The MPAC method directly emulates the channel model through the spatial distribution of the probes. In the RTS method, the link connections between transmitter and receiver are assigned in a one-to-one manner using "air interface direct connection," analogous to a cable connection (also known as a "virtual cable"). This approach meets the requirements of a full-device test, preserves the coupling between antennas and the noise interference between hardware and antennas, and more realistically reflects the MIMO performance of a wireless device. Contents of the invention

[0007] The invention is based on the technical problem of how an OTA test is to be carried out on radio devices.

[0008] According to a first aspect, an embodiment provides a system for OTA testing of a radio device, the system for OTA testing comprising a test device and at least two test antennas, wherein: the test antennas are designed to establish a wireless communication connection between the test device and the radio device, so that wireless communication between the test device and the radio device is possible; the test device is designed to: for determining the inverse matrix of a spatial transmission matrix assigned to several subfrequency bands between the test device and the radio device; for determining a desired test signal having a preset frequency band and for dividing the desired test signal having the preset frequency band into desired test signals assigned to the plurality of subfrequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands; for loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an OTA test of the radio.

[0009] According to a second aspect, in one embodiment, a method for OTA testing of a radio device is provided, the method for OTA testing comprising: Determining the inverse matrix of a spatial transmission matrix assigned to several subfrequency bands between the test device and the radio device;

[0010] Determining a desired test signal having a preset frequency band and dividing the desired test signal having the preset frequency band into desired test signals assigned to the plurality of subfrequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands;

[0011] Loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an OTA test of the radio.

[0012] According to the third aspect, a testing device is provided in one embodiment, comprising: an inverse matrix determination module configured to determine the inverse matrix of a spatial transmission matrix associated with a plurality of subfrequency bands between the test device and the radio device; a subfrequency band detection module configured to detect a desired test signal having a preset frequency band and to divide the desired test signal having the preset frequency band into desired test signals assigned to the plurality of subfrequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands; an inverse matrix loading module configured to load the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an over-the-air test of the radio.

[0013] According to the fourth aspect, a computer-readable storage medium is provided in one embodiment, on which a program is stored that is executable by a processor to implement the method for OTA testing of a radio device described in any of the above embodiments.

[0014] According to the system for OTA testing of a radio device, the method, and the test apparatus of the above-mentioned embodiments, the inverse matrix of a spatial transmission matrix assigned to a plurality of sub-frequency bands is obtained between the test apparatus and the radio device, and the desired test signal having a preset frequency band is frequency-band-divided into desired test signals assigned to the plurality of sub-frequency bands, and finally, the inverse matrix of the spatial transmission matrix assigned to the respective sub-frequency bands is loaded onto the desired test signals assigned to the respective sub-frequency bands to establish a virtual cable connection between the test apparatus and the radio device and perform an OTA test of the radio device. Short description of the drawings Fig. Figure 1 is a schematic diagram of a prior art MIMO channel model; Fig. Figure 2 is a schematic diagram of the structure of a known 2×2 multiple-input-multiple-output (MIMO) test system; Fig. 3 is a schematic diagram of a crosstalk signal in the 2x2 multiple input multiple output (MIMO) test system; Fig. Figure 4 is a schematic diagram of the overall transmit matrix in the 2×2 multiple-input-multiple-output (MIMO) test system; Fig. 5 is a schematic diagram of the structure of a system for OTA testing of a radio device according to an embodiment; Fig. Figure 6 is a schematic diagram illustrating the division of a desired test signal with a preset frequency band into subfrequency bands; Fig. 7 is a flowchart of a method for OTA testing of a radio device according to an embodiment; Fig. 8 is a schematic diagram of the structure of a test device according to an embodiment. Specific embodiments

[0015] The present invention will now be described in more detail using specific embodiments with reference to the drawings. Similar elements from different embodiments are designated by similar reference numerals. In the following embodiments, many detailed descriptions are provided to facilitate understanding of the present application. However, those skilled in the art can easily recognize that some of the features may be omitted or replaced with other elements, materials, or methods in other situations. In some cases, some processes related to the present application are not illustrated or described in the description to avoid obscuring the essential part of the present application due to excessive description.It is not necessary for those skilled in the art to describe these processes in detail, and they can fully understand the relevant processes based on the explanation in the description and general technical knowledge in this field.

[0016] Furthermore, the features, processes, or special features described in the description can be combined in any convenient manner to form various embodiments. Furthermore, the steps or actions in the method description can also be interchanged or adapted in terms of order in a manner obvious to a person skilled in the art. Therefore, the various sequences in the description and the figures serve only to clearly describe a specific embodiment and do not represent a mandatory sequence, unless otherwise stated that a specific sequence must be followed.

[0017] In context, the serial numbers assigned to components, such as "first," "second," etc., serve only to distinguish the described objects and do not indicate any sequential or technical significance. The terms "connection" and "coupling" used in this application include both direct and indirect connections (couplings), unless otherwise stated.

[0018] The Radiated Two-Stage (RTS) method in the MIMO OTA test procedure is presented below.

[0019] In a MIMO OTA test, the expression for the transmitted test signal and the received test signal is: y(t)=H(t)∗x(t) where y(t) represents the received test signal, x(t) the transmitted test signal, and H(t) the spatial transmission matrix. When performing a received performance test of a radio, an N×N test system with N test antennas and N receiver ports of the radio is taken as an example, and the spatial transmission matrix H(t) is expressed as: H(t)=[h1,1(t)⋯h1,N(t)⋮⋱⋮hN,1(t)⋯hN,N(t)] where h 1,1 (t) represents the transmission parameters of the communication link between the first transmit port of the test equipment (connected to the first test antenna, the same applies hereinafter) and the first receive port of the radio equipment; h 1,N (t) represents the transmission parameters of the communication link between the Nth transmit port of the test equipment (connected to the Nth test antenna, the same applies hereinafter) and the first receive port of the radio equipment; h N,1(t) represents the transmission parameters of the communication link between the first transmit port of the test equipment and the Nth receive port of the radio equipment; and h N,N (t) represents the transmission parameters of the communication link between the Nth transmit port of the test equipment and the Nth receiver port of the radio. Since crosstalk exists between the test antenna and the radio's receiver port, the crosstalk signals caused by crosstalk are eliminated by loading the inverse matrix M(t) of the spatial transmission matrix before the test equipment's transmit port. The expression of the inverse matrix M(t) of the spatial transmission matrix in an N×N system is: M(t)=[m1,1(t)⋯m1,N(t)⋮⋱⋮mN,1(t)⋯mN,N(t)] where m 1,1 (t) represents the inverse transmission parameter of the communication link between the first transmit port of the test equipment and the first receive port of the radio equipment; m1,N (t) represents the inverse transmission parameter of the communication link between the Nth transmit port of the test equipment and the first receive port of the radio equipment; m N,1 (t) represents the inverse transmission parameter of the communication link between the first transmit port of the test equipment and the Nth receive port of the radio equipment; and m N,N (t) represents the inverse transmission parameter of the communication link between the Nth transmit port of the test equipment and the Nth receive port of the radio equipment.

[0020] Using the example of a reception performance test with 2×2 MIMO, as in Fig. As shown in Figure 3, the transmit signal results from processing with the base station emulator and the channel emulator, taking the antenna directional pattern into account. During the test, the desired transmit signals are those transmitted from transmit port 1 of the test device to receiver port 1 of the radio, or from transmit port 2 of the test device to receiver port 2 of the radio. Therefore, the crosstalk signals transmitted from transmit port 1 to receiver port 2 of the radio, or from transmit port 2 to receiver port 1 of the radio, are interference signals in a MIMO test. The spatial transmission matrix H in a 2×2 test system can be described as follows: H2×2(t)=[h1,1(t)h1,2(t)h2,1h2,2(t)]

[0021] Due to the presence of crossover connections, the test signals integrated with the channel model cannot be correctly transmitted to the respective receiver ports of the radio. Therefore, an inverse matrix is ​​used to eliminate the effects of crosstalk and implement a "direct connection of the air interfaces," i.e., a virtual cable connection, between the test device and the radio. The inverse matrix can be implemented using amplifiers, attenuators, and phase shifters (or digital signal processing) in a channel emulator.

[0022] After loading the inverse matrix of the spatial transfer matrix, the relationship between the transmit signal and the receive signal is: y(t)=[H(t)M(t)]∗x(t)

[0023] As in Fig. As shown in Figure 4, the total transmission matrix T of the 2×2 MIMO system is defined as follows: [h11h12h21h22][m11m12m21m22]=T where, T=[t11t12t21t22]=[H2×2(t)M2×2(t)]=[h11h12h21h22][m11m12m21m22] Ideally, the matrix T is an identity matrix, so t 11 = t 22 = 1, t 12 = t 21= 0. Here, the test signal transmitted from the test device's transmit port 1 is transmitted only to the radio's receiver port 1, and the test signal transmitted from the test device's transmit port 2 is transmitted only to the radio's receiver port 2. By introducing the inverse matrix, crosstalk signals are eliminated. However, in practical connections, crosstalk signals cannot be completely eliminated due to signal reflections, power, and limited phase control accuracy in the test system. To evaluate the influence of crossed channels on test accuracy, the term "isolation degree" is introduced in related technologies. This term represents the amplitude ratio between the crosstalk signal and the desired signal and is defined as follows: Ios1=|t11 / t12| Ios2=|t22 / t21| Iost=min(Ios1,Ios2) where Ios1 and Ios2 represent the ratio of the desired signal to the crosstalk signal of the receiver port 1 and the receiver port 2 of the radio, respectively, and Ios t The system isolation level of the 2×2 MIMO test system. If the isolation level reaches a certain specified value, it is interpreted that a good "direct connection of the air interfaces" can be established. In a MIMO OTA test, the isolation level is one of the key factors influencing test errors. The isolation level depends on the relative position of the radio and the test antenna, as well as the antenna directivity pattern of the radio and the test antenna.

[0024] Therefore, the RTS method first determines the radio's antenna directivity pattern and spatial transmission matrix, and then calculates the inverse matrix of the spatial transmission matrix. The calculation of the inverse matrix insertion into the test signal compensates for the spatial transmission matrix and realizes the "direct connection of the air interfaces" between the base station emulator (BSE) and the device under test (DUT) to perform a MIMO OTA test.

[0025] As communication bandwidth increases and communication link designs become more complex, amplitude-phase mismatches within a link lead to reduced isolation of the radio's receiver port within the bandwidth, which poses a significant challenge for MIMO measurements. Radio frequency components in the link, such as radio frequency cables, amplifiers, attenuators, filters, etc., modulate the amplitude and phase within the bandwidth in different ways. If the test signals were narrowband signals, these modulation-induced signal distortions would be insignificant. However, as bandwidth increases, the amplitudes and phases of the various signals within the bandwidth vary considerably depending on frequency upon reaching the test center.This amplitude-phase mismatch within the broadband leads to large test errors in MIMO tests, regardless of whether the radiated two-stage (RTS) method or the multi-probe anechoic chamber (MPAC) method was used in the prior art.

[0026] In 4G MIMO testing, the test signal is a narrowband signal (with a frequency of 20 MHz or less). Since the amplitude and phase of the narrowband signal change little within the frequency band, the narrowband signal closely matches the center frequency. The inverse matrix of the spatial transfer matrix obtained according to the center frequency of the frequency band using the above RTS method can achieve a good degree of isolation (e.g., more than 20 dB) across the entire frequency band, so amplitude-phase consistency issues can be ignored. In 5G broadband MIMO testing, the amplitude and phase change dramatically across a wide frequency band with increasing system bandwidth.Applying the inverse matrix of the spatial transmission matrix calculated according to the center frequency of the frequency band using the above RTS method to the entire wide frequency band will result in poor antenna isolation, making it difficult to achieve "direct connection of the air interfaces", resulting in great uncertainty in MIMO testing and even making it impossible to evaluate the real performance of the radio under test.

[0027] In one embodiment of the present invention, a broadband test signal is divided into a plurality of narrowband test signals, wherein the inverse matrix of a spatial transmission matrix is ​​calculated in each narrow frequency band and this inverse matrix of the spatial transmission matrix is ​​loaded onto the narrowband test signal in order to perform an OTA test of a radio device.

[0028] With reference to Fig. 5, an embodiment of the present invention provides a system for OTA testing of a radio device, wherein the radio device 200 represents a radio device under test, and the radio device 200 has at least two receiver ports 202 (transmitter ports 203), and each receiver port 202 (transmitter port 203) is connected to a receive / transmit antenna 201. The system for OTA testing provided in this embodiment includes a test antenna 101 and a test device 102, wherein the test device 101 has at least two transmit ports 103 (receive ports 104), and each transmit port 103 (receive port 104) is connected to a test antenna 101, wherein the test antenna 101 establishes a wireless communication link between the test device 102 and the radio device 200 to enable wireless communication between the test device 102 and the radio device 200.The test device 102 is connected to the test antenna 101 or the radio 200 via a wired or wireless connection. The anechoic chamber 300 serves to provide an electromagnetic environment for the test. It should be noted that in . Fig. 5, the test device 102 is arranged within the anechoic chamber 300. In a further embodiment, the test device 102 can also be arranged outside the anechoic chamber 300. The test device 102 is configured to perform the following operations to perform an OTA test of a radio device 200: (i) Determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the test device 102 and the radio device 200.

[0029] In one embodiment, determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands comprises: determining an inverse downlink matrix and / or determining an inverse uplink matrix, wherein the inverse downlink matrix represents the inverse of the spatial transmission matrix associated with multiple subfrequency bands between the test device 102 and the receiver of the radio device 200, and the inverse uplink matrix represents the inverse of the spatial transmission matrix associated with multiple subfrequency bands between the transmitter of the radio device 200 and the test device, which are to be explained in more detail below. (1) In a reception performance test of the radio 200, the inverse downlink matrix is ​​determined in the following manner.

[0030] Each transmitting port 103 of the test device 102 transmits signals of the respective subfrequency bands, and the amplitude changes of the signals of the respective subfrequency bands are detected, which are transmitted by each transmitting port 103 of the test device 102 and received by each receiving port 201 of the radio device 200. In this embodiment, the transmitting port 103 currently transmitting signals is regarded as the current transmitting port 103, and at this time, the other transmitting ports 103 are in a deactivated state. When the current transmitting port 103 is transmitting signals, the current transmitting port 103 can be controlled to transmit the signals of the respective subfrequency bands sequentially.When the current transmitting port 103 transmits a signal of the current subfrequency band, it is possible to either control one or more of the receiver ports 201 of the radio device 200 to receive the signal of the current subfrequency band, or to control all receiver ports 201 of all radio devices 200 to simultaneously receive the signal of the current subfrequency band. After all receiver ports 201 of the radio device 200 have received the amplitude change of the signal of the current subfrequency band, the current transmitting port 103 is then controlled to transmit the signal of the next subfrequency band, and finally, the amplitude changes of the signals of the respective subfrequency bands transmitted by the current test antenna 101 and received by all receiver ports 201 of the radio device 200 are determined.In an analogous manner, the amplitude changes of the signals of the respective subfrequency bands transmitted by each transmitting port 103 and received by each receiving port 201 of the radio device 200 can be determined by successively acting as the current transmitting port 103 by the other transmitting ports 103.

[0031] The signals of the respective sub-frequency bands are transmitted multiple times from any two transmitting ports 103 of the test device 102 with different phase differences, and the phase differences of the signals of the respective sub-frequency bands are determined, which are separately transmitted from any two transmitting ports 103 and received by each receiving port 201 of the radio device 200. In this embodiment, the transmitting ports 103 that are currently transmitting signals are regarded as the first current transmitting port 103 and the second current transmitting port 103, and the other transmitting ports 103 are in a deactivated state.When the first current transmit terminal 103 and the second current transmit terminal 103 transmit signals of the current sub-frequency band with different phase differences, either one or more receiver terminals 201 of the radio device 200 can be controlled to receive the signals of the current sub-frequency band or all receiver terminals 201 of the radio device 200 can be controlled to receive the signals of the current sub-frequency band simultaneously.After the reception of the phase differences of the signals of the current sub-frequency band by the receiver terminal 201 of the radio device 200 has been determined, the first current transmitting terminal 103 and the second current transmitting terminal 103 are then controlled to transmit the signals of the next sub-frequency band with different phase differences multiple times and finally determine the phase differences of the signals of the respective sub-frequency bands transmitted from the first current transmitting terminal 103 and the second current transmitting terminal 103 and received by all the receiver terminals 201 of the radio device 200.In an analogous manner, the phase differences of the signals of the individual subfrequency bands transmitted by any two transmit ports 103 and received by each receiver port 201 of the radio device 200 can be determined by sequentially acting as the first current transmit port 103 and the second current transmit port.

[0032] In one embodiment, the phase difference of the current sub-frequency band signal received by the receiver port 201 of the radio device 200 can be calculated as follows: based on the amplitudes of the current sub-frequency band signals transmitted by the first current transmit port 103 and the second current transmit port 103 and received by each receiver port 202 of the radio device and on the amplitude of the composite signal (ie the signal transmitted jointly by the first current transmit port 103 and the second current transmit port 103), this phase difference is calculated by Fourier series approximation or Fourier transform.In another embodiment, the phase difference may also be calculated as follows: First, a reference value of the composite amplitude is calculated based on the amplitudes of the signals of the current sub-frequency band transmitted from the first current transmitting port 103 and the second current transmitting port 103, respectively, and received by each receiver port 202 of the radio device 200. The reference value of the composite amplitude is a calculated value of the amplitude of a composite signal obtained by combining the aforementioned respective transmitted signals of the current sub-frequency band with different phase differences at each receiver port 202 of the radio device 200. Then, this phase difference is calculated based on the calculated reference value of the composite amplitude and the amplitude of the composite signal obtained by the aforementioned test.

[0033] By means of amplitude changes and phase differences of the signals of the respective subfrequency bands transmitted by the test device 102 and received by the radio device 200, the spatial transmission matrix associated with a plurality of subfrequency bands is determined between the transmitting port 103 of the test device 102 and the receiving port 202 of the radio device 200, whereby the inverse matrix of the spatial transmission matrix is ​​determined.

[0034] In an embodiment where n transmit ports 103 and n receive ports 202 are taken as an example, the spatial transmission matrix associated with the i -th subfrequency band can be determined according to the following expression: H(fi)=[p11ejχ11(fi)p12ejχ12(fi)⋯p1nejχ1n(fi)p21ejχ21(fi)p22ejχ 22(fi)⋯p2nejχ2n(fi)⋮⋮⋱⋮pn1ejχn1(fi)pn2ejχn2(fi)⋯pnnejχnn(fi)], where f irepresents the center frequency of the i -th subfrequency band, i is the index number of the subfrequency band, where i = 1, 2, ..., I and I is the number of subfrequency bands; p vk represents the amplitude change of the signal sent from the k-th transmit terminal 103 to the v-th receiver terminal 202, and e jXvk represents the phase difference of the signal transmitted from the k-th transmit port 103 to the v-th receive port 202, where v=1,2,... ,n and k=1,2,... ,n.

[0035] From the spatial transmission matrix associated with the aforementioned i-th subfrequency band, the inverse matrix M i (f i ) of the spatial transmission matrix associated with the i-th subfrequency band as follows: Mi(fi)=[mi,11(fi)⋯mi,1n(fi)⋮⋱⋮mi,n1(fi)⋯mi,nn(fi)], where f irepresents the center frequency of the i-th subfrequency band, i is the index number of the subfrequency band, where i = 1, 2, ..., I and I is the number of subfrequency bands; m i,vk (f i ) represents the inverse transmission parameter of the signal sent from the k-th transmit port 103 to the v-th receive port 202.

[0036] In this embodiment, the inverse matrix M W a broadband spatial transmission matrix associated with the preset frequency band according to the following expression: MW=[m1,1'⋯m1,n'⋮⋱⋮mn,1'⋯mn,n'] where mv,k'=[m1,vk(f1) … mi,vk(fi) … mI,vk(fI)], mv,k' the inverse matrix of the transmission matrix of the wireless communication link between the k-th transmit port 103 and the v-th receiver port 202 at frequencies f1,...,f i ,...f I This means that mv,k' is actually a vector, and each value in this vector represents an inverse transmission parameter associated with a respective subfrequency band. (2) In a transmit power test of the radio 200, the inverse uplink matrix is ​​determined in the following manner.

[0037] Each transmitter port 204 of the radio device 200 transmits signals of the respective subfrequency bands, and the amplitude changes of the signals of the respective subfrequency bands transmitted by each transmitter port 204 of the radio device 200 and received by each receiver port 104 of the test device 102 are detected. In this embodiment, the transmitter port 204 currently transmitting signals is considered the current transmitter port 204, and at this time, the other transmitter ports 204 are in a deactivated state. When the current transmitter port 204 is transmitting signals, the current transmitter port 204 can be controlled to transmit the signals of the respective subfrequency bands sequentially.When the current transmitter port 204 transmits the signal of a current subfrequency band, it is possible to either control one or more of the receive ports 104 of the test device 102 to receive the signal of the current subfrequency band, or to control all receive ports 104 of all test devices 102 to simultaneously receive the signal of the current subfrequency band. After all receive ports 104 of the test device 102 have received the amplitude change of the signal of the current subfrequency band, the current transmitter port 204 is then controlled to transmit the signal of the next subfrequency band, and finally, the amplitude changes of the signals of the respective subfrequency bands transmitted by the current transmitter port 204 and received by all receive ports 104 of the test device 102 are determined.In an analogous manner, the amplitude changes of the signals of the respective subfrequency bands transmitted by each transmitter port 204 and received by each receiver port 104 of the test device 102 can be determined by successively acting as the current transmitter port 204 by the other transmitter ports 204.

[0038] The signals of the respective sub-frequency bands are transmitted multiple times from any two transmitter ports 204 of the radio device 200 with different phase differences, and the phase differences of the signals of the respective sub-frequency bands are determined, each of which is transmitted from any two transmitter ports 204 and received by each receive port 104 of the test device 102. In this embodiment, the transmitter ports 204 that are currently transmitting signals are considered the first current transmitter port 204 and the second current transmitter port 204, and the other transmitter ports 204 are in a deactivated state.When the first current transmitter terminal 204 and the second current transmitter terminal 204 transmit signals of the current sub-frequency band with different phase differences, either one or more receive terminals 104 of the test device 102 can be controlled to receive the signals of the current sub-frequency band or all receive terminals 104 of the test device 102 can be controlled to receive the signals of the current sub-frequency band simultaneously.After the reception of the phase differences of the signals of the current sub-frequency band by the receiving terminal 104 of the test device 102 has been determined, the first current transmitter terminal 204 and the second current transmitter terminal 204 are then controlled to transmit the signals of the next sub-frequency band with different phase differences multiple times and finally determine the phase differences of the signals of the respective sub-frequency bands transmitted by the first current transmitter terminal 204 and the second current transmitter terminal 204 and received by all the receiving terminals 104 of the test device 102.In an analogous manner, the phase differences of the signals of the respective subfrequency bands transmitted by any two transmitter ports 204 and received by each receive port 104 of the test device 102 can be determined by sequentially acting as the first current transmitter port 204 and the second current transmitter port 204.

[0039] The spatial transmission matrix corresponding to a plurality of subfrequency bands between the transmitter port 204 of the radio device and the test device is determined by the amplitude change and phase difference of the signals of the individual subfrequency bands transmitted by the radio device 200 and received by the test device 102, thereby determining the inverse matrix of the spatial transmission matrix.

[0040] It should be noted that the operating state of the test device and the radio device can be either a transmitting state or a receiving state. The specific method for determining an inverse downlink matrix through a received power test has already been described in detail in the previous embodiment. According to the principle of transmit-receive reciprocity, the test results obtained through a transmit power test and a receive power test should be consistent with each other. Therefore, the specific method for determining the inverse uplink matrix through a transmit power test is not repeated in this embodiment. (ii) The test device 102 determines a desired test signal with a preset frequency band, and the desired test signal with a preset frequency band is divided by frequency band into desired test signals assigned to a plurality of subfrequency bands, wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands. In this embodiment, the preset frequency band is a frequency band with a wider bandwidth. In the 5G combination, a frequency bandwidth of, for example, 100 MHz or 400 MHz is typically used. It should be noted that when dividing the preset frequency band into a plurality of subfrequency bands, the general rule applies: the more subfrequency bands are divided, the smaller the amplitude difference of the signals in each subfrequency band, and the higher the final test accuracy.However, too many frequency bands will result in excessive utilization of the resources of the control processor (FPGA or DSP) in the test device 102. Therefore, in this embodiment, the phase difference between desired test signals in any two subfrequency bands is smaller than a preset phase value. In one embodiment, the preset phase value may be 10°. As shown in . Fig. 6, a preset frequency band of 100 MHz is divided into 10 subfrequency bands (B1, B2, ..., B10), and it will be understood by those skilled in the art that this preset phase value is adaptable to the actual application requirements and this embodiment is not limited thereto.

[0041] Furthermore, the desired test signal with the preset frequency band determined by the test device 102 is a signal in the time domain. In this embodiment, the desired test signal with the preset frequency band is to be converted from the time domain to the frequency domain, wherein, in the frequency domain, the desired test signal with the preset frequency band is divided by frequency band into desired test signals assigned to a plurality of subfrequency bands. As an example, a desired test signal with a preset frequency band can be converted from the time domain to the frequency domain by discrete Fourier transformation.

[0042] In an embodiment using the wireless communication link between the test device 102 and the receiver port of the radio device 200 as an example, the specific operations are as follows: (2-1) Determine a desired test signal xv,k (p) having a preset frequency band required for a wireless communication link between the k-th transmit port 103 of the test device 102 and the v-th receiver port 202 of the radio device 200, where k represents the index number of the transmit port 103 of the test device 102 and v represents the index number of the receiver port 202 of the radio device 200. (2-2) Convert the desired test signal x v,k (p) with the preset frequency band required for the wireless communication link between the k-th transmit terminal 103 and the v-th receive terminal 202 of the radio device 200, from the time domain to the frequency domain to generate a frequency domain-related desired test signal X v,k(w) with a preset frequency band of the wireless communication link between the k-th transmit port 103 and the v-th receive port 202 of the radio device 200. As an example, a desired test signal x v,k (p) converted from the time domain to the frequency domain with a preset frequency band according to the following expression: Xv,k(w)=∑p=0P−1xv,k(p)e−j2πwpP where P is the length of the discrete Fourier transform, which can be 128, 256, 512 or 1024. (2-3) Divide the desired test signal X v,k (w) into desired test signals in the frequency domain which are assigned to a plurality of sub-frequency bands, whereby the desired test signals X assigned to a plurality of sub-frequency bands i,vk (w) can be determined in the frequency domain. (iii) The test device 102 loads the inverse matrix of the spatial transmission matrix associated with the respective subfrequency bands onto the desired test signals associated with the respective subfrequency bands to determine transmit test signals associated with the respective subfrequency bands, thereby establishing a virtual cable connection between the radio device 200 and the test antenna 101 and performing an OTA test of the radio device 200. The OTA test of the radio device 200 performed by the test device 102 includes at least one of the following steps: controlling the test antenna 101 to transmit a transmit test signal having a preset frequency band to the radio device 200 to determine the wireless reception power of the radio device 200; or controlling the radio device 200 to transmit a transmit test signal having a preset frequency band to the test antenna 101 to determine the wireless transmission power of the radio device 200.

[0043] In this embodiment, the test device 102 loads, in the frequency domain, the inverse matrix of the spatial transmission matrix associated with the respective subfrequency bands onto the desired test signals associated with the respective subfrequency bands. Therefore, it is also necessary to convert the frequency-domain transmit test signals associated with the respective subfrequency bands to the time domain. As an example, the frequency-domain transmit test signals can be converted to the time domain using inverse discrete Fourier transform.

[0044] In an embodiment using the wireless communication link between the test device 102 and the receiver port of the radio device 200 as an example, the specific operations are as follows: (3-1) Loading the inverse transfer parameter vector (mv,k'=[m1,vk(f1) … mi,vk(fi) … mI,vk(fI)]) the wireless communication link between the k-th transmit port 103 of the test device 102 and the v-th receive port 202 of the radio device 200 in the inverse matrix of the spatial transmission matrix assigned to the respective frequency bands to the desired test signals X i,vk (w) which are assigned to several sub-frequency bands in the frequency range to transmit the test signals Xi,vk'(w), which are assigned to the respective subfrequency bands in the frequency range of the wireless communication link between the k-th transmit port of the test device 102 and the v-th receiver port 202 of the radio device 200. Determining the transmit test signals Xi,vk'(w), which are assigned to the respective subfrequency bands in the frequency range of the wireless communication link between the k-th transmit port 103 of the test device 102 and the v-th receive port 202 of the radio device 200, according to the following expression: Xi,vk'(w)=Xi,vk(w)mi,vk(fi) (3-2) Converting the transmit test signals Xi,vk'(w), which are assigned to the respective sub-frequency bands in the frequency domain, from the frequency domain to the time domain in order to transmit signals Xi,vk'(p), which are assigned to the respective subfrequency bands of the wireless communication link between the k-th transmit port 103 of the test device 102 and the v-th receive port 202 of the radio device 200. As an example, the transmit test signals assigned to the respective subfrequency bands Xi,vk'(w) converted from the frequency domain to the time domain according to the following expression: xi,vk(p)=∑w=0P−1Xi,vk(w)rj2πwpP (3-3) In one embodiment, the transmit test signal of the k-th transmit port 103 of the test device 102 in each subfrequency band is as follows: Txi,v=∑k=1nxi,vk where Tx i,vrepresents the transmit test signal of the k-th transmit port 103 of the test device 102 in the i-th subband.

[0045] The embodiment of the present invention solves the problems of low isolation degree and low test accuracy caused by the high amplitude-phase imbalance in a desired test signal having a preset frequency band with a wider bandwidth by dividing the desired test signal having the preset frequency band with the wider bandwidth into desired test signals assigned to a plurality of sub-frequency bands, and then loading a calculated inverse matrix of a spatial transfer matrix assigned to the respective sub-frequency bands onto the desired test signals assigned to the respective sub-frequency bands, thereby performing an OTA test of the radio device.

[0046] With reference to Fig. 7 shows Fig. 7 is a flowchart of the method for OTA testing of a radio device according to an embodiment, wherein the method provided in this embodiment is applied to a test device and comprises steps 10 to 30, which are described in detail below.

[0047] Step 10: Determine the inverse matrix of a spatial transmission matrix assigned to several subfrequency bands between the test device and the radio device.

[0048] In one embodiment, in step 10, determining the inverse matrix of a spatial transmission matrix assigned to multiple subfrequency bands between the test device and the radio device comprises the following: determining an inverse downlink matrix and / or determining an inverse uplink matrix. The inverse downlink matrix represents the inverse matrix of a spatial transmission matrix assigned to the multiple subfrequency bands between the test device and the radio device's receiver, and the inverse uplink matrix represents the inverse matrix of a spatial transmission matrix assigned to the multiple subfrequency bands between the radio device's transmitter and the test device.

[0049] In one embodiment, determining a downlink inverse matrix comprises: Step 11-1: Determine the amplitude changes of signals of the respective sub-frequency bands, which are transmitted separately from each transmitting port of the device under test and received by each receiving port of the radio. In this step, the signal transmission and reception process should be performed multiple times, with only one transmitting port transmitting the signal at a time and the other transmitting ports being disabled. In a single signal transmission and reception process, either one or more receiver ports of the radio can be controlled to receive the signal, or all antennas of the radio can be controlled to receive simultaneously to increase efficiency. As one embodiment, the amplitude of the signal received by each receiver port of the radio can be determined by a performance report of the respective receiver ports of the radio, where the performance report can be, for example, RSSI (Integrated Radio Frequency Intensity).Reference Signal Strength Indicator (RSRP) or Reference Signal Received Power (RSRP). In this embodiment, the test antenna can be controlled during the signal transmission and reception process to transmit signals of the respective subfrequency bands one after the other to detect amplitude changes in the signals of the respective subfrequency bands transmitted from this transmit port and received by each receiver port.

[0050] Step 12-1: Determine the phase differences of signals of the respective subfrequency bands simultaneously transmitted from any two transmitting ports of the test device and received by each receiver port of the radio. In this step, the phase differences of the signals of the respective subfrequency bands separately transmitted from any two transmitting ports and received by each receiver port of the radio can be determined from the amplitudes of the signals of the respective subfrequency bands separately transmitted from any two transmitting ports and the amplitude of the composite signal received by each receiver port. By controlling any two transmitting ports to transmit the signals of the respective subfrequency bands multiple times with different phase differences, the amplitude of the composite signal received by each receiver port can be determined.In this step, the signal transmission and reception process is to be performed several times, with two transmit ports transmitting signals at a time and the other transmit ports being deactivated. Optionally, in a single signal transmission and reception process, either one or more receiver ports of the radio can be controlled to receive signals, or all receiver ports can be controlled to receive signals simultaneously to increase efficiency. As one embodiment, the phase differences are calculated as follows: Based on the amplitude of the signals transmitted by any two transmit ports and received by each receiver port of the radio and the amplitude of a composite signal (i.e., a signal transmitted jointly by the two transmit ports) received by each receiver port of the radio, the phase difference is determined by Fourier series approximation or Fourier transform.As another embodiment, the phase difference is calculated as follows: First, a composite amplitude reference value is calculated, which is the amplitude value of the signals separately transmitted from any two transmitting terminals and received by each receiving terminal of the radio. Here, the composite amplitude reference value is a calculated amplitude value of a composite signal obtained by combining the above-mentioned separately transmitted signals at each receiving terminal of the radio with different phase differences. Subsequently, the phase difference is calculated based on the calculated composite amplitude reference value and the amplitude of the composite signal obtained by the above test.In this embodiment, in each transmission-reception operation of the signal, any two transmitting terminals that transmit signals can be controlled to transmit signals of the respective sub-frequency bands one after another to detect the phase difference of the signals of the respective sub-frequency bands that are separately transmitted from any two transmitting terminals and received by each receiving terminal of the radio device.

[0051] Step 13-1: Determine the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the test device and the radio receiver based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands. This means that each subfrequency band is associated with an inverse matrix of the spatial transmission matrix. It should be noted that the method for determining the inverse matrix of the spatial transmission matrix has already been described in detail in a previous embodiment and will not be repeated here.

[0052] In one embodiment, determining the inverse uplink matrix comprises: Step 11-2: Determining the amplitude changes of signals of the respective subfrequency bands transmitted by each transmitter port of the radio and received by each receiver port 204 of the test equipment.

[0053] Step 12-2: Determine the phase differences of signals of the respective subfrequency bands transmitted simultaneously from any two transmitter ports 204 of the radio and received by each receive port of the test equipment.

[0054] Step 12-3: Determine the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the radio transmitter and the test equipment based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands.

[0055] It should be noted that the operating state of the test device and the radio device can be either a transmitting state or a receiving state. The specific method for determining the inverse downlink matrix through a received power test has already been described in detail in a previous embodiment. According to the principle of transmit-receive reciprocity, the test results obtained through a transmit power test or a received power test should be consistent with each other. Therefore, the specific method for determining the inverse uplink matrix through a transmit power test will not be repeated in this embodiment.Step 20: Determining a desired test signal with a preset frequency band and subdividing the desired test signal with the preset frequency band into desired test signals assigned to the multiple subfrequency bands; where the preset frequency band corresponds to a frequency band consisting of the multiple subfrequency bands. Theoretically, in this embodiment, the more subfrequency bands generated by subdividing the preset frequency band, the more favorable the performance. As the number of subfrequency bands increases, the phase changes of the signals in each subfrequency band should be very small. However, too many subfrequency bands will consume more resources of the control processor in the test device, making it necessary to select an appropriate number of subfrequency bands.In this embodiment, the desired test signals assigned to the plurality of sub-frequency bands must satisfy the phase difference between the desired test signals assigned to any two sub-frequency bands being smaller than a preset phase value, which is 10° in this embodiment. Note that in this embodiment, a desired test signal with a preset frequency band in the frequency domain is frequency-band-divided into desired test signals assigned to a plurality of sub-frequency bands. Therefore, the desired test signal with the preset frequency band must first be converted from the time domain to the frequency domain and then divided into the desired test signals assigned to the plurality of sub-frequency bands.

[0056] Step 30: Loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to acquire transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the radio and the test equipment and performing an over-the-air test of a radio. The over-the-air test of the radio performed by the test equipment includes at least one of the following steps: controlling the test antenna to transmit a transmit test signal with a preset frequency band to the radio to determine the wireless receive power of the radio; or controlling the radio to transmit a transmit test signal with a preset frequency band to the test antenna to determine the wireless transmit power of the radio.In this embodiment, the test device loads the inverse matrix of the spatial transmission matrix associated with the respective subfrequency bands onto the desired test signals associated with the respective subfrequency bands in the frequency domain. Therefore, it is also necessary to convert the transmit test signals in the frequency domain associated with the respective subfrequency bands to the time domain. As one embodiment, an inverse discrete Fourier transform can be used to convert the transmit test signals associated with the respective subfrequency bands to the time domain.

[0057] With reference to Fig. 8, an embodiment of the present invention further provides a test apparatus comprising an inverse matrix determination module 1001, a subfrequency band determination module 1002, and an inverse matrix loading module 1003.

[0058] The inverse matrix detection module 1001 is designed to determine the inverse matrix of a spatial transmission matrix assigned to a plurality of subfrequency bands between the test device and the radio device.

[0059] The subfrequency band detection module 1002 is configured to acquire a desired test signal having a preset frequency band and to divide the desired test signal having the preset frequency band into desired test signals associated with the plurality of subfrequency bands by frequency band; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands.

[0060] The inverse matrix loading module 1003 is configured to load the inverse matrix of the spatial transmission matrix associated with the respective subfrequency bands onto the desired test signals associated with the respective subfrequency bands to acquire transmit test signals associated with the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an over-the-air test of the radio.

[0061] The various modules in the test device provided in this embodiment correspond to the method steps in the preceding embodiments, and their specific embodiments have already been described in detail in the preceding embodiments and will not be repeated here.

[0062] It will be understood by those skilled in the art that all or part of the functions of the various methods in the above embodiments can be implemented in the form of both hardware and computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored on a computer-readable storage medium, which can include read-only memory, random access memory, floppy disk, CD-ROM, hard disk, etc., and the program is executed by a computer to implement all or part of the above functions. For example, the program is stored in the memory of a device, and when the program in the memory is executed by a processor, all or part of the above functions can be realized.Furthermore, when all or part of the functions in the aforementioned embodiments are realized using computer programs, the program can be stored on a storage medium such as a server, another computer, a floppy disk, a CD-ROM, a USB flash drive, or an external hard disk, and can be downloaded or copied to the memory of a local device, or a system version update for the local device can be performed. When the program in the memory is executed by the processor, all or part of the functions of the aforementioned embodiments can be realized.

[0063] The above specific examples serve to illustrate the present invention. They are intended merely to aid understanding of the present invention and are not intended to limit the present invention. Those skilled in the art may make further derivations, modifications, or substitutions in accordance with the spirit of the present invention.

Claims

[1] System for over-the-air testing of a radio device, characterized by that the system for over-the-air testing comprises a test device and at least two test antennas, where: the test antennas are designed to establish a wireless communication connection between the test device and the radio device, so that wireless communication between the test device and the radio device is possible; the test device is designed to: for determining the inverse matrix of a spatial transmission matrix assigned to several subfrequency bands between the test device and the radio device; for determining a desired test signal having a preset frequency band and for dividing the desired test signal having the preset frequency band into desired test signals assigned to the plurality of subfrequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands; for loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands in order to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an over-the-air test of the radio. [2] System for over-the-air testing according to claim 1, characterized bythat determining the inverse matrix of a spatial transmission matrix associated with a plurality of subfrequency bands between the test equipment and the radio equipment comprises: determining an inverse downlink matrix and / or determining an inverse uplink matrix. [3] System for over-the-air testing according to claim 2, characterized by that determining the inverse downlink matrix includes: Detecting the amplitude changes of signals of the respective subfrequency bands transmitted from each transmit port of the test equipment and received by each receive port of the radio equipment. Detecting the phase differences of signals of the respective sub-frequency bands transmitted simultaneously from any two transmit ports of the test equipment and received by each receive port of the radio equipment; Determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the test equipment and the radio receiver based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands. [4] System for over-the-air testing according to claim 2, characterized by that determining the inverse uplink matrix includes: Determining the amplitude changes of signals of the respective sub-frequency bands transmitted by each transmitter port of the radio equipment and received by each receive port of the test equipment; Determining the phase differences of signals of the respective sub-frequency bands transmitted simultaneously from any two transmitter ports of the radio equipment and received by each receive port of the test equipment; Determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the radio transmitter and the test equipment based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands. [5] Over-the-air test system according to claim 1, characterized by that dividing the desired test signal with the preset frequency band into desired test signals assigned to the plurality of sub-frequency bands comprises: Converting the desired test signal having a preset frequency band from the time domain to the frequency domain and, in the frequency domain, subdividing the desired test signal having a preset frequency band frequency band-wise into desired test signals associated with the plurality of sub-frequency bands. [6] System for over-the-air testing according to claim 5, characterized bythat the desired test signals assigned to the plurality of subfrequency bands must satisfy that the phase difference between the desired test signals assigned to any two subfrequency bands is smaller than a preset phase value. [7] System for over-the-air testing according to claim 5, characterized by that loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the corresponding subfrequency bands in order to determine transmit test signals assigned to the respective subfrequency bands comprises: Loading the inverse matrix of the spatial transmission matrix corresponding to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals in the frequency domain assigned to the respective subfrequency bands; and Converting the transmission test signals in the frequency domain assigned to the respective sub-frequency bands from the frequency domain to the time domain in order to determine transmission test signals assigned to the respective sub-frequency bands. [8] Procedure for over-the-air testing of a radio device, characterized by that the procedure for over-the-air testing includes: Determining the inverse matrix of a spatial transmission matrix assigned to several subfrequency bands between the test device and the radio device; Determining a desired test signal having a preset frequency band and dividing the desired test signal having the preset frequency band into desired test signals associated with the plurality of sub-frequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of sub-frequency bands. Loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an over-the-air test of the radio. [9] Method for over-the-air testing according to claim 8, characterized by that determining the inverse matrix of a spatial transmission matrix associated with a plurality of subfrequency bands between the test equipment and the radio equipment comprises: determining an inverse downlink matrix and / or determining an inverse uplink matrix. [10] Method for over-the-air testing according to claim 9, characterized by that determining the inverse downlink matrix includes: Determine the amplitude changes of signals of the respective subfrequency bands transmitted by each transmit port of the test equipment and received by each receive port of the radio equipment. Detecting the phase differences of signals of the respective sub-frequency bands transmitted simultaneously from any two transmit ports of the test equipment and received by each receive port of the radio equipment; Determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the test equipment and the radio receiver based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands. [11] Method for over-the-air testing according to claim 9, characterized by that determining the inverse uplink matrix includes: Detecting the amplitude changes of signals of the respective sub-frequency bands transmitted by each transmitter port of the radio equipment and received by each receive port of the test equipment; Detecting the phase differences of signals of the respective sub-frequency bands transmitted simultaneously from any two transmitter ports of the radio equipment and received by each receive port of the test equipment; Determining the inverse matrix of a spatial transmission matrix associated with multiple subfrequency bands between the radio transmitter and the test equipment based on the amplitude changes and phase differences associated with the signals of the respective subfrequency bands. [12] Method for the over-the-air test according to claim 8, characterized bythat dividing the desired test signal with the preset frequency band frequency band-wise into the plurality of sub-frequency bands assigned desired test signals comprises the following: Converting the desired test signal having a preset frequency band from the time domain to the frequency domain and, in the frequency domain, subdividing the desired test signal having a preset frequency band frequency band-wise into desired test signals associated with the plurality of sub-frequency bands. [13] Method for the over-the-air test according to claim 12, characterized by that loading the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the corresponding subfrequency bands in order to determine transmit test signals assigned to the respective subfrequency bands comprises: Loading the inverse matrix of the spatial transmission matrix corresponding to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals in the frequency domain assigned to the respective subfrequency bands; Converting the transmit test signals assigned to the respective subfrequency bands from the frequency domain to the time domain to determine transmit test signals assigned to the respective subfrequency bands. [14] Test device, characterized by that the test equipment includes: an inverse matrix determination module configured to determine the inverse matrix of a spatial transmission matrix associated with a plurality of subfrequency bands between the test device and the radio device; a subfrequency band detection module configured to detect a desired test signal having a preset frequency band and to divide the desired test signal having the preset frequency band into desired test signals assigned to the plurality of subfrequency bands; wherein the preset frequency band corresponds to a frequency band consisting of the plurality of subfrequency bands; an inverse matrix loading module configured to load the inverse matrix of the spatial transmission matrix assigned to the respective subfrequency bands onto the desired test signals assigned to the respective subfrequency bands to determine transmit test signals assigned to the respective subfrequency bands, thereby establishing a virtual cable connection between the test device and the radio and performing an over-the-air test of the radio. [15] A computer-readable storage medium, characterized by that a program is stored on the storage medium which is executable by a processor in order to implement the method for over-the-air testing according to one of claims 8 to 13.

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