Virtual cable calibration in over-the-air conformance testing

Abstract

Various example embodiments relate to apparatuses, methods, apparatus, and computer-readable media for virtual cable calibration in over-the-air conformance testing. In an example embodiment, a terminal device may receive training signals from at least four probes; estimating a channel based on the received training signal; and transmitting a representation of the estimated channel to a test device coupled to the at least four probes. The terminal device and the at least four probes are located in a test chamber. The estimated channel includes an over-the-air OTA channel portion between the at least four probes and the terminal device. A representation of the estimated channel is sent to a test device for compensation of the OTA channel portion.

Description

Technical Field

[0001] Various example embodiments described herein relate generally to communication technology, and more particularly to devices, methods, apparatus, and computer-readable media for virtual cable calibration in over-the-air (OTA) conformance testing. Background Art

[0002] Certain abbreviations that may appear in the specification and / or drawings are defined as follows:

[0003] 3GPP Third Generation Partnership Project

[0004] CSI-RS Channel State Information Reference Signal

[0005] DUT Device Under Test

[0006] FR1 Frequency Range 1

[0007] FR2 Frequency Range 2

[0008] MIMO Multiple Input Multiple Output

[0009] mTRP Multiple Send and Receive Points

[0010] Multi-Rx

[0011] NAS Non-Access Stratum

[0012] OTA

[0013] QCL Quasi-Co-sited

[0014] RAN4 Radio Access Network Working Group 4

[0015] RAN5 Radio Access Network Working Group 5

[0016] RSRP Reference Signal Received Power

[0017] UE User Equipment

[0018] VCC Virtual Cable Calibration

[0019] In 3GPP, Radio Access Network Working Group 4 (RAN4) is responsible for defining the radio frequency (RF) requirements for both base stations and user equipment (UE), and RAN5 is responsible for developing conformance test specifications for UE. RF requirements in frequency range 1 (FR1) are verified by traditional conducted test methods using transmission lines (e.g., coaxial cables connecting the device under test (DUT) to the test system). In contrast, frequency range 2 (FR2) RF requirements are verified by over-the-air (OTA) test methods because the millimeter wave antenna is directly connected to the RF front-end amplifier and there is no antenna connector, which makes it physically impossible to connect the DUT to the test system via a cable. In addition, beamforming is used in FR2 to overcome high path loss and line-of-sight obstruction. OTA test methods are needed to describe beam characteristics and to check beam acquisition and beam tracking performance. Summary of the invention

[0020] The following provides a brief summary of exemplary embodiments to provide a basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define the scope of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a prelude to the more detailed description provided below.

[0021] In a first aspect, an example embodiment of a terminal device is provided. The terminal device may include at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the terminal device to at least: receive training signals from at least four probes; estimate a channel based on the received training signals; and send a representation of the estimated channel to a test device coupled to the at least four probes. The terminal device and the at least four probes are located in a test room. The channel includes an over-the-air OTA channel portion between the at least four probes and the terminal device. The representation of the estimated channel is sent to the test device for compensation of the OTA channel portion.

[0022] In a second aspect, an example embodiment of a test device is provided. The test device may include at least one processor and at least one memory. The at least one memory stores instructions that, when executed by the at least one processor, cause the test device to at least: send a training signal to a terminal device through at least four probes; receive from the terminal device a representation of a channel estimated by the terminal device, the channel including an over-the-air OTA channel portion between the at least four probes and the terminal device; derive a virtual cable calibration matrix for compensation of the OTA channel portion from the channel representation; and compensate for the OTA channel portion using the virtual cable calibration matrix. The terminal device and the at least four probes are located in a test chamber.

[0023] Also provided are example embodiments of methods, apparatus, and computer-readable media for virtual cable calibration in over-the-air (OTA) conformance testing. Such example embodiments generally correspond to the example embodiments of the terminal device and test device described above, and for convenience, a repeated description thereof is omitted herein.

[0024] Other features and advantages of example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Some example embodiments will now be described by way of non-limiting examples with reference to the accompanying drawings.

[0026] Figure 1 is a schematic block diagram illustrating a conduction test system.

[0027] Figure 2 is a schematic block diagram illustrating an over-the-air (OTA) test system.

[0028] Figure 3 is a schematic block diagram illustrating an OTA test system including a virtual cable calibration (VCC) block according to an example embodiment of the present disclosure.

[0029] Figure 4 is a message flow diagram illustrating a process according to an example embodiment of the present disclosure.

[0030] Figure 5 is a message flow diagram illustrating a process according to an example embodiment of the present disclosure.

[0031] Figure 6 is a message flow diagram illustrating a process according to an example embodiment of the present disclosure.

[0032] Figure 7 is a message flow diagram illustrating a process according to an example embodiment of the present disclosure.

[0033] Figure 8 is a schematic block diagram illustrating an apparatus according to an example embodiment of the present disclosure.

[0034] Fig. 9 is a schematic block diagram illustrating an apparatus according to an example embodiment of the present disclosure.

[0035] Fig.10 is a schematic block diagram illustrating a terminal device according to an example embodiment of the present disclosure.

[0036] Fig.11 is a schematic block diagram illustrating a test equipment arrangement according to an example embodiment of the present disclosure.

[0037] In all drawings, the same or similar reference numerals represent the same or similar elements, and repeated description of the same elements will be omitted. DETAILED DESCRIPTION

[0038] Hereinafter, some example embodiments will be described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known circuits, techniques, and components are shown in block diagram form to avoid obscuring the concepts and features described.

[0039] Figure 1 A conventional conductive test system 100 for FR1 requirement verification is schematically illustrated. Figure 1 As shown in FIG. 1 , the test system 100 may include a test equipment (TE) 110, a channel emulator 112, a test chamber 116, and a device under test (DUT) 120. The channel emulator 112 and the test chamber 116 are arranged in a Figure 1 Although shown as separate devices, they may be integrated as part of the test device 110 .

[0040] The test equipment 110 may include a system simulator (SS) that simulates the behavior of a base station, such as an evolved Node-B (eNB) or a next-generation Node-B (gNB). The DUT 120 may be implemented as a user equipment (UE) (also referred to as a terminal device), which is located in a test room 116 and connected to a channel emulator 112 and then to the test equipment 110 via a cable. Figure 1 In the example shown in FIG. 1 , the DUT 120 has two H and V dual polarized antenna panels / modules 122a, 122b. Figure 1 An example 4×4 system is shown, in which the four Rx antenna ports of the DUT 120 are connected to the four Tx antenna ports of the test equipment 110 through cables respectively via the channel emulator 112. The test equipment 110 generates four signals x1, x2, x3, x4, and transmits the signals from the four Tx antenna ports to the four Rx antenna ports of the DUT 120 via the channel emulator 112. The channel emulator 112 simulates the L Represents the wireless channel, the channel matrix H L The received signals x1, x2, x3, x4 are mixed and a linear combination of the signals x1, x2, x3, x4 is generated at each output of the channel emulator 112. The number of output branches of the channel emulator 112 depends on the number of RX antenna ports or antenna connectors present at the DUT 120, which is Figure 1In the example shown, it is 4. The linear combination signal is then sent from the output branch of the channel emulator 112 to the four Rx antenna ports of the DUT 120 via cables.

[0041] Since the signals are sent through the cable, they are well isolated from each other and there is no crosstalk / interference experienced in the channel, except for the crosstalk deliberately introduced by the channel emulator 112. Assuming the cable is perfect and has unity gain, i.e., there is no crosstalk between the cables or from the cable connectors, and there is no loss, then the channel H of the cable is cable can be modeled as a 4th order identity matrix. Then, the signal received at the DUT 120 can be modeled as (ignoring noise):

[0042] y = H L x (1)

[0043] where x is a column vector consisting of the transmitted signals (x1,x2,x3,x4)' (the prime symbol indicates the transpose of a vector or matrix), H L is the wireless channel matrix simulated at the channel emulator 112, and y is the signal received at the DUT 120. The channel emulator 112 converts the simulated wireless channel matrix H L Applied to signals x1, x2, x3, x4 to simulate the crosstalk / interference generated by the wireless channel for the purpose of conformance testing of UEs deployed in the field.

[0044] RAN4 is studying the requirements for FR2 multi-Rx chain downlink reception, aiming to specify the requirements for the reception of 4-layer downlink multiple-input multiple-output (MIMO) signals, and the reception from two different directions at the UE at the same time. As mentioned above, the RF requirements in FR2 need to be verified through over-the-air (OTA) testing. Figure 2 A Multi-TRP Multi-Rx OTA test system 200 is schematically illustrated, wherein a test chamber 116 (designed as an anechoic chamber in this case) is equipped with a plurality of probes (also referred to as probe antennas) located at different positions for generating beams in different directions. Figure 2 Two dual-polarized (i.e., cross-polarized) antenna probes 117a, 117b are shown at two different locations in the test chamber 116, and each dual-polarized antenna probe 117a, 117b may include two probes with different polarizations. The number of output branches of the channel emulator 112 depends on the number of probes in the test chamber 116. Figure 2In the example shown, there are 4. Four probes (collectively referred to as 117) are connected to the four output branches of the channel emulator 112 through cables, respectively, and then connected to the four Tx antenna ports of the test equipment 110. As described above, the channel emulator 112 generates a linear combination of the received signals x1, x2, x3, and x4 at each output branch, and the linear combination signal is sent to the DUT 120 placed in the test chamber 116 through the probe 117. It can be understood that the test chamber 116 can be equipped with more dual-polarization antenna probes at different locations, and each dual-polarization antenna probe can include at least two probes with different polarizations.

[0045] The DUT 120 placed in the test chamber 116 has two dual-polarized antenna panels / modules 124a, 124b. In an ideal case, when the DUT 120 is positioned at a specific location with a specific orientation, the first dual-polarized antenna panel 124a receives the first beam (beam 1) transmitted from the first dual-polarized antenna probe 117a, and the second dual-polarized antenna panel 124b receives the second beam (beam 2) transmitted from the second dual-polarized antenna probe 117b. However, since the wireless link between the dual-polarized antenna probes 117a, 117b and the DUT 120 is an unguided medium, the signal transmitted using a specific polarization of a given probe will be received at the two polarizations of the two DUT antenna modules / panels, causing undesirable crosstalk / interference during testing. The signal received at the DUT 120 can then be modeled as (ignoring noise):

[0046] y=H OTA H L x (2)

[0047] where x is a column vector containing the transmitted signal (x1, x2, x3, x4)', H L is the wireless channel matrix simulated at the channel emulator 112, H OTA is the inherent channel matrix of the OTA test chamber 116 , representing the OTA channel between the probe 117 and the DUT 120 , and y is the signal received at the DUT 120 .

[0048] Mitigation or elimination of crosstalk / interference introduced within the test chamber 116 is essential to obtaining correct test results, which can be achieved through wireless / virtual cable solutions. Wireless / virtual cable is a theoretical concept in which the effective channel between the channel emulator 112 and the DUT antenna module / panel is designed to be a unit matrix through appropriate calibration operations. More generally, virtual cable is a technical term used in testing to describe a connection between two points or devices that meets a specific set of isolation requirements between the separate links that make up the connection. It is defined to be media-independent and is generally understood to be an extension of the concept of wired cable in situations where wired cable cannot be used. In addition, virtual cable calibration is considered to be the process of improving the isolation between virtual cable links until the isolation requirements are met. The challenge for wireless / virtual cable solutions is that the OTA channel matrix H OTA It is difficult to characterize, making it difficult to determine an effective virtual cable calibration (VCC) matrix. Current methods for determining the VCC matrix include a brute force phase search method that adjusts the phase over a 360° range to determine the optimal phase for the channel coefficients, which is computationally complex and requires a long estimation time. It will take hours to determine the calibration matrix, which is too long for multiple Rx tests with various angles of arrival (AoA) to find enough DUT / probe positions.

[0049] Example embodiments of the present disclosure present a faster, simpler solution to obtain a valid VCC matrix for OTA testing, and potentially with greater isolation. In an example embodiment, the DUT can estimate the overall channel using a downlink training signal sent from the test equipment, and then send a representation of the estimated overall channel to the test equipment for compensation of the OTA channel portion. The test equipment can derive a valid VCC matrix from the estimated overall channel that pre-compensates for the crosstalk / interference introduced in the OTA channel portion, thereby producing a wireless / virtual cable connection for OTA conformance testing that performs comparable to a cable connection. The example embodiments also present three effective methods for the DUT to transmit / send a channel representation to the test equipment.

[0050] Figure 3is a schematic block diagram illustrating an OTA test system 300 according to an example embodiment of the present disclosure. The test system 300 includes a virtual cable calibration (VCC) block 114, which is located between the channel emulator 112 and the test chamber 116, and is used to pre-compensate for the effects of the OTA channel between the dual-polarized antenna probes 117a, 117b (i.e., four probes 117) and the DUT 120. The channel emulator 112 and the VCC block 114 can be implemented as separate devices, or can be integrated as a functional block in the test device 110. Similarly, the test chamber 116 can be implemented as a separate device, or it can be integrated as a functional block in the test device 110. Other aspects of the test system 300 can be similar to the test system 200 discussed above, and will not be repeated here.

[0051] Figure 4 4 is a message flow diagram illustrating a process 400 according to an example embodiment of the present disclosure. The process 400 may be performed in the test system 300, for example. Figure 4 Only the test equipment 110 and the DUT 120 are shown. It is understood that the channel emulator 112 and the VCC block 114 may be integrated in the test equipment 110, or the operation of the channel emulator 112 and the VCC block 114 implemented as separate devices may become apparent from the following description related to the operation of the test equipment 110 and the DUT 120.

[0052] refer to Figure 4 , the test device 110 may transmit a training signal to the DUT 120 at 410. The training signal may be transmitted from the 2P transmit antenna ports of the test device 110 and received at the 2P receive antenna ports of the DUT 120, where P is an integer greater than 1 and the factor of 2 is to account for dual polarization / cross polarization. Then, the total channel for transmission of the training signal between the 2P transmit antenna ports of the test device 110 and the 2P receive antenna ports of the DUT 120 may be represented by a 2P×2P matrix. Figure 3 In the example shown in , P=2, and four training signals x1, x2, x3, x4 are transmitted from the four transmit antenna ports of the test device 110 and received at the four receive antenna ports of the DUT 120, and thus the total channel matrix includes 16 elements / coefficients. The training signals may be defined in the time domain, in which case the training signals x1, x2, x3, x4 are transmitted from the four transmit antenna ports of the test device 110; or the training signals may be defined in the frequency domain, in which case the training signals are combined into transmit signals x1, x2, x3, x4 and transmitted from the four transmit antenna ports of the test device 110.

[0053] In an example embodiment, the training signal may be a reference signal with a dedicated or specific configuration selected from a channel state information reference signal (CSI-RS), a data demodulation reference signal (DM-RS), a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a tracking reference signal (TRS), a phase tracking reference signal (PT-RS), or a positioning reference signal (PRS), or may also be communication data. Before sending the training signal, the test device 110 may send the configuration of the training signal to the DUT 120 so that the DUT 120 knows the training signal to be sent from the test device 110.

[0054] During the transmission of the training signal, the wireless channel matrix H L is applied at the channel emulator 112, and the virtual cable calibration (VCC) matrix H VCC is applied at the VCC block 114. It should be noted here that the VCC matrix H applied at the VCC block 114 for the transmission of the training signal VCC It may not be possible to compensate for crosstalk / interference introduced in the OTA channel portion within the test chamber 116 because the test equipment 110 has not received any information about the OTA channel portion. The VCC matrix H applied at the VCC block 114 VCC can be set to the default matrix, which is represented here as H VCCd , to distinguish it from the VCC matrix H generated to compensate for the OTA channel part as described below VCC In an exemplary embodiment, the wireless channel matrix H L and the default VCC matrix H VCCd can be set as reversible matrices, that is, they have inverse matrices (H L ) -1 and (H VCCd ) -1 For example, the wireless channel matrix H L and the default VCC matrix H VCCd Each may be set as a unitary matrix. The signal received at the DUT 120 may be modeled as (ignoring noise):

[0055] y = H OTA H VCCd H L x (3)

[0056] Where x is a column vector consisting of the transmitted signals (x1, x2, x3, x4)', H L is the wireless channel matrix simulated at the channel emulator 112, H VCCd is the default VCC matrix applied at the VCC module 114, H OTAis the inherent channel matrix of the OTA test chamber 116, and y is the signal received at the DUT 120. In the exemplary embodiment, to simplify the subsequent calculation of the OTA channel matrix H OTA Estimation of the simulated wireless channel matrix H L and the default VCC matrix H VCCd is set to the identity matrix. If the matrix H L and H VCCd Both are set to the identity matrix, then Formula 3 can be rewritten as (ignoring noise):

[0057] y = H OTA x (4).

[0058] When the DUT 120 receives the training signal from the test equipment 110, the DUT 120 may estimate the channel based on the received training signal at 412. Here, the estimation is performed on the entire channel from the transmit antenna port of the test equipment 110 to the receive antenna port of the DUT 120, which includes the OTA channel portion between the dual-polarized antenna probes 117a, 117b (i.e., four probes 117) and the DUT 120. Since the DUT 120 has knowledge of the training signal x transmitted from the test equipment 110, it can estimate the channel based on the training signal x and the received signal y according to the above formula 3. The DUT 120 may estimate the channel as H OTA H VCCd H L .exist Figure 3 In the example shown in FIG, the channel estimate H OTA H VCCd H L It can be represented by a 4×4 channel matrix.

[0059] Then, at 414, the DUT 120 may send a representation of the estimated channel, H, to the test equipment 110 for compensation of the OTA channel portion. OTA The DUT 120 may send the estimated channel matrix H to the test equipment 110. OTA H VCCd H L Each element / coefficient of , or the estimated channel matrix H may be sent to the test device 110 OTA H VCCd H L Other information obtained will be discussed in detail below.

[0060] After receiving the channel representation, the test equipment 110 may derive the VCC matrix H at 416. VCC For example, the test equipment 110 may first calculate H OTA HVCCd H L (H L ) -1 (H VCCd ) -1 To obtain the OTA channel matrix H OTA , where (H L ) -1 and (H VCCd ) -1 They are H L and H VCCd If the wireless channel matrix H L With the default VCC matrix H VCCd If both are set to the identity matrix, this calculation can be omitted, and the test equipment 110 can directly use the channel estimate received from the DUT 120 as the OTA channel matrix H according to the above formula 4 OTA Then the test equipment 110 can derive the matrix H for compensating the OTA channel OTA The VCC matrix H VCC In an example embodiment, the test equipment 110 may derive the VCC matrix H VCC is the OTA channel matrix H OTA The inverse or pseudo-inverse of H VCC =(H OTA ) -1 .

[0061] The test equipment 110 can be based on the obtained VCC matrix H VCC To perform virtual cable calibration for consistency testing of DUT 120 at 418. For example, test equipment 110 may set VCC module 114 to generate the resulting VCC matrix H VCC =(H OTA ) -1 OTA channel part (ie H OTA ) will be composed of VCC matrix H VCC The test equipment 110 and the DUT 120 can then be used to perform OTA conformance testing using the calibrated test system 300.

[0062] In process 400, by estimating the channel based on the training signal by the DUT 120 and sending the channel estimation information back to the test equipment 110, the test equipment 120 can quickly and easily find the VCC matrix for compensating for the crosstalk / interference introduced in the OTA channel portion. The test equipment 110 can use the VCC matrix to perform calibration to establish a wireless / virtual cable connection for OTA consistency testing. Compared with existing methods, process 400 has reduced computational complexity and lower time cost, and can achieve performance comparable to that of a cable connection. The test signals sent from the test equipment 110 to the DUT 120 via the OTA channel portion will be well isolated, just as if they were sent in a cable, which ensures that correct test results will be obtained in the OTA consistency test.

[0063] Also presented herein are some example methods for the DUT 120 to send the channel representation to the test equipment 110. In one example embodiment, the DUT 120 may send the channel representation to the test equipment 110 via a UE Assistance Information framework. Figure 5 A process 500 of transmitting a channel representation through a UE assistance information framework according to an example embodiment of the present disclosure is illustrated.

[0064] refer to Figure 5 At 510, DUT 120 may report to test equipment 110 its ability to support channel estimation reporting for compensation of the OTA channel portion. For example, a new information element (IE) may be defined in a conventional UE capability report message to indicate that the UE (i.e., DUT 120) has the ability to report channel estimation for compensation of the OTA channel portion during UE conformance testing. An example of a new information element in a UE capability report message is as follows:

[0065]

[0066] The field “Hota-Feedback-Ind-r1x” is included and its value is set to “supported” to indicate that the UE is able to provide channel estimation feedback for compensation of the OTA channel portion to the test device 110 .

[0067] In response to the capability report received from the DUT 120, the test device 110 may send a configuration for channel estimation to the DUT 120 at 512. The configuration may enable the DUT 120 to trigger the UE assistance information procedure and report channel estimation information to the test device 110. In one example, the configuration may also specify a periodicity and / or prohibition time for channel estimation information reporting. An example of a configuration for channel estimation is shown below:

[0068]

[0069] The field "Hota-feedback-config-r1X" configures the UE (i.e., DUT 120) to report channel estimation information to inform the base station (i.e., test equipment 110) about the UE estimate of the channel from the Tx antenna port of the base station to the Rx antenna port of the UE. The field "Hota-Feedback-Config-ProhibitTimer" indicates the time when reporting channel estimation information is prohibited since the last report, and it can have a value in seconds. The value s0 means that the prohibit timer is set to 0 seconds and is therefore disabled, the value s0.5 means that the prohibit timer is set to 0.5 seconds, the value s1 means that the prohibit timer is set to 1 second, and so on. When the prohibit timer is running, the DUT 120 is prohibited from sending channel estimation information to the test equipment 110, thereby preventing too frequent channel estimation reports and reducing RRC signaling overhead.

[0070] When the DUT 120 receives a configuration including the field "Hota-feedback-config-r1X" set to "setup", the DUT 120 will estimate the channel as described above and send a representation of the channel estimate to the test equipment 110 at 514. In an example, the DUT 120 may periodically estimate the channel and report the channel representation until it receives a command from the test equipment 110 to stop reporting the channel estimation information. For example, if the DUT 120 receives a channel estimation configuration in which the field "Hota-feedback-config-r1X" is set to "release", the DUT 120 will stop reporting the channel estimation information to the test equipment 110. In an example embodiment, the DUT 120 may report the representation of the channel estimated by the DUT 120 in a UE Assistance Information message, but it may also send the channel representation in another message. An example of a UE Assistance Information message including a channel representation is shown below:

[0071]

[0072] In this example, the proposed "UEAssistanceInformation-v18xx-IEs" contains a field "OTA-Matrix-Elements-List" which is used to send a list of channel coefficients of the estimated channel back to the test device 110 for compensation of the OTA channel part. The field "max-Elements-OTA-Matrix" indicates the size of the list, i.e., the number of coefficients / elements included in the 2P×2P channel matrix, which is Figure 3In the example shown, it is 16. The field "OTA-RxPower-Range" indicates the estimated and quantized power value in each coefficient of the estimated channel matrix. In an example embodiment, the field "OTA-RxPower-Range" may have a quantized value ranging from 0 to N-1, where N is the number of quantization levels. For example, if the field "OTA-RxPower-Range" has a value of n, the actual value may be calculated as:

[0073] ActualValue=Lmin+n*(Lmax-Lmin) / (N-1)dBm (5)

[0074] Where Lmin and Lmax represent the lower and upper limits of the reference signal received power (RSRP) level to be reported. For N quantization levels, the quantization step size Δ can be calculated as:

[0075] △=(Lmax-Lmin) / (N-1) (6)

[0076] It can be understood that for a certain range from Lmin to Lmax, a smaller quantization step size Δ will result in more quantization levels N and therefore more bits are needed to transmit the channel unit / coefficient list. For example, for a channel matrix including 2P*2P coefficients, the list of "OTA-RxPower-Range" has a length of (2P) 2 *ceil(log2(N)) bits, or (1 / 8)*(2P)2*ceil(log2(N)) bytes. The values ​​of Lmin, Lmax and N may be determined according to future 3GPP RAN4 protocols.

[0077] In the above example, the quantized power value (i.e., RSRP value) is sent to the test device 110 as a channel coefficient. It is understood that the channel coefficient may include at least one of a power, an amplitude, and a phase value. For example, each channel coefficient may include an amplitude and a phase value to define a complex coefficient. The amplitude and phase values ​​may be quantized and sent in a similar manner, and repeated description is omitted here.

[0078] In another example embodiment, the DUT 120 may send a channel representation to the test equipment 110 via a UE-specific conformance test function. Figure 6 A process 600 of sending a channel representation by a UE-specific conformance test function according to an example embodiment of the present disclosure is illustrated.

[0079] See also Figure 6, at 610, the test equipment 120 may send a UE conformance test command to the DUT 120, instructing the DUT 120 to report channel estimation information for compensation of the OTA channel portion. The UE conformance test command may be sent in a non-access stratum (NAS) message, which may have a standard layer 3 message format. In an example embodiment, the UE conformance test command may activate a UE demodulation performance test preparation function (UDPTPF) (or a different function, or the function may have a different name) at the DUT 120, by which the DUT 120 performs necessary preparation operations for the UE demodulation performance conformance test, including, for example, reporting channel estimation information to the test equipment 110 for compensation of the OTA channel portion. The UDPTPF may be mandatory for UEs operating in FR2.

[0080] In response to the received UE conformance test command, the DUT 120 may estimate the channel based on the received training signal and send a representation of the estimated channel (e.g., quantized channel coefficients) to the test device 110 in a UE conformance test response message at 612. The quantization and transmission of the channel coefficients have been described above with respect to the UE assistance information, and a repeated description is omitted here.

[0081] In an example embodiment, the DUT 120 may also periodically report the channel representation to the test equipment 110 at 614. The period of the channel representation reporting may be specified in the UE conformance test command or predefined / preconfigured at the DUT 120. The DUT 120 may keep periodically reporting the channel representation until it receives a command to stop doing so from the test equipment 110. For example, if the DUT 120 receives a command from the test equipment 110 to deactivate the UDPTPF function, the DUT 120 will stop reporting the channel representation to the test equipment 110.

[0082] In another example embodiment, the DUT 120 may send the channel representation to the test equipment 110 by reusing a Type II, or enhanced Type II (eType II) precoding matrix indicator (PMI) feedback framework. Figure 7 A process 700 for sending a channel representation through a PMI feedback framework is illustrated according to an example embodiment of the present disclosure.

[0083] refer to Figure 7At 710, the test device 110 may send a channel state information reference signal (CSI-RS) configured as the above-mentioned training signal to the DUT 120. Before sending the CSI-RS, the test device 110 may configure the DUT 120 to receive the CSI-RS signal on 2P (P>1) orthogonal CSI-RS ports, and use a type II codebook, an enhanced type II codebook, or an extension thereof to periodically or aperiodically report measurements for the 2P orthogonal CSI-RS ports. As described above, the DUT 120 may estimate the channel based on the received CSI-RS.

[0084] At 712, the DUT 120 may measure the CSI-RS and send a measurement report containing channel state information (CSI) to the test device 110. The CSI may include, among other things, a precoding matrix indicator (PMI) determined based on a type II codebook, an enhanced type II (eType II) codebook, or another extension thereof. The PMI indicates a precoding matrix associated with a channel estimate determined at the DUT 120. In an example embodiment, the PMI is used as a representation of an estimated channel that is sent to the test device 110.

[0085] At 714, the test equipment 110 can derive the VCC matrix H from the PMI. VCC For example, the test device 110 may first derive an estimate of the channel from the PMI. In an example embodiment, the test device 110 may use the precoding matrix indicated by the PMI as the conjugate transpose of the overall channel matrix, ie, (H OTA H VCCd H L ) H =PMI_Matrix (the superscript "H" indicates the conjugate transpose / Hermitian of a vector or matrix). Then, the test equipment 110 can derive the VCC matrix H from the channel estimate. VCC For example, the test equipment 110 may first calculate H OTA H VCCd H L (H L ) -1 (H VCCd ) -1 To obtain the OTA channel matrix H OTA , then the VCC matrix H is obtained VCC is the OTA channel matrix H OTA The inverse or pseudo-inverse of H VCC =(H OTA ) -1 .

[0086] Optionally, if the resulting VCC matrix H VCCIf the OTA channel part cannot be fully compensated, further operations can be performed to refine the resulting VCC matrix H VCC In an example embodiment, the test equipment 110 may use the derived VCC matrix H at 716 VCC For example, the test equipment 110 may set the VCC block 114 to generate a VCC matrix H for compensating the OTA channel portion. VCC The compensated OTA channel part can be expressed as (H OTA H VCC ).

[0087] At 718, the test equipment 110 may iteratively perform the above steps 710 to 714 to obtain a new VCC matrix H VCC For example, the test equipment 110 may send a new CSI-RS as a new training signal to the DUT 120, receive a new CSI including a new PMI from the DUT 120, and derive a new VCC matrix H from the new PMI. VCC Here, in order to distinguish the previously obtained VCC matrix from the new VCC matrix, the previous VCC matrix is ​​represented by H VCCp , and the new VCC matrix is ​​denoted as H VCCn . New VCC matrix H VCCn is derived as follows:

[0088] H VCCn =(H OTA H CCCp ) -1 (7).

[0089] At 720, the test device 110 may determine whether the OTA channel portion is adequately compensated. For example, the test device 110 may calculate the residual crosstalk of the compensated OTA channel portion as a new VCC matrix H VCCn 722 based on the new VCC matrix H. VCCn To update the previous VCC matrix H VCCp For example, the test equipment 110 can use the new VCC matrix H VCCn The obtained disturbance is used to update the previous VCC matrix H VCCp The algorithm can be used to determine the VCC matrix H from the new VCCnThe disturbance of the previous VCC matrix H is updated VCCp The OTA channel part can be better compensated, ie the residual crosstalk is further reduced.

[0090] At 724, the test device 110 may repeatedly perform steps 716 to 722 until the OTA channel portion is sufficiently compensated, ie, the residual crosstalk is below a threshold. The process 700 then proceeds to step 726 to perform UE conformance testing.

[0091] In process 700, the VCC matrix H VCC can be trained (i.e., updated) over multiple cycles and eventually converge to a target matrix that can adequately compensate for the OTA channel portion. In process 700, a training algorithm similar to that used in a neural network training process can be used. In an example embodiment, steps 716 to 724 can be periodically re-executed to maintain the VCC matrix H VCC Verified and ensure the accuracy of OTA conformance test results.

[0092] Figure 8 8 is a schematic block diagram illustrating an apparatus 800 according to an example embodiment of the present disclosure. The apparatus 800 may be implemented to include, or form at least a portion of the above-mentioned DUT 120 to perform at least a portion of the operations associated with the DUT 120. Figures 1 to 7 The operations related to the DUT 120 are discussed, so the blocks of the apparatus 800 will be briefly described here, and the details thereof may refer to the above description.

[0093] refer to Figure 8 , the apparatus 800 may include: a first component 810 for receiving a training signal from at least four probes; a second component 820 for estimating a channel based on the received training signal; and a third component 830 for sending a representation of the estimated channel to a test device coupled to the at least four probes.

[0094] In an example embodiment, the apparatus 800 and at least four probes may be located in a test room. A training signal may be transmitted from 2P transmit antenna ports of the test equipment and received at 2P receive antenna ports of the apparatus 800, where P is an integer greater than 1. The estimated channel is the channel between the 2P transmit antenna ports and the 2P receive antenna ports, and it includes an over-the-air (OTA) channel portion between the at least four probes and the apparatus 800. The apparatus 800 transmits a channel representation to the test equipment for compensation of the OTA channel portion.

[0095] In an exemplary embodiment, the third component 830 may send the channel representation to the test device in a user equipment assistance information message. The apparatus 800 may also include: a fourth component (not shown) for reporting to the test device a capability of supporting channel estimation reporting for compensation of the OTA channel portion; and a fifth component (not shown) for receiving a configuration for estimating the channel from the test device. The apparatus 800 may send the channel representation to the test device according to the received configuration for channel estimation.

[0096] In an example embodiment, the third component 830 may send a channel representation to the test device through a user equipment dedicated consistency test function. For example, the apparatus 800 may further include: a sixth component (not shown) for receiving a user equipment consistency test command from the test device; and a seventh component (not shown) for sending a user equipment consistency test response to the test device in response to the user equipment consistency test command, the user equipment consistency test response including the channel representation.

[0097] In an example embodiment, the channel representation sent to the test device may be encoded as a list of channel coefficients for the channel, and the channel coefficients may include at least one of power, amplitude, and phase values.

[0098] In an example embodiment, the third component 830 may use a type II codebook, an enhanced type II codebook, or another extension thereof to send a channel representation to the test device through a precoding matrix indicator PMI feedback. For example, the apparatus 800 may also include: an eighth component (not shown) for receiving a channel state information reference signal sent from the test device as a training signal; and a ninth component (not shown) for sending a measurement report of the channel state information reference signal to the test device. The measurement report includes: a PMI determined based on the type II codebook, the enhanced type II codebook, or another extension thereof. The PMI indicates a precoding matrix associated with the estimated channel.

[0099] In an example embodiment, the eighth component and the ninth component may be configured to repeatedly perform the operations of receiving a channel state information reference signal and sending a measurement report until the OTA channel portion is sufficiently compensated.

[0100] Fig. 9 1 is a schematic block diagram of an apparatus 900 according to an example embodiment of the present disclosure. The apparatus 900 may be implemented to include, or form at least a portion of, the above-mentioned test device 110 to perform at least a portion of the operations associated with the test device 110. Figures 1 to 7 The operations related to the test device 110 are discussed, so the blocks of the apparatus 900 will be briefly described here, and the details thereof can be referred to the above description.

[0101] See also Fig. 9 , the apparatus 900 may include: a first component 910, for sending a training signal to a terminal device through at least four probes; a second component 920, for receiving a representation of a channel estimated by the terminal device from the terminal device; a third component 930, for deriving a virtual cable calibration matrix from the channel representation; and a fourth component 940, for compensating an OTA channel portion using the virtual cable calibration matrix.

[0102] In an example embodiment, a terminal device and at least four probes may be placed in a test room. A training signal may be transmitted from 2P transmit antenna ports of apparatus 900 and received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1. The channel estimated by the terminal device is a channel between the 2P transmit antenna ports and the 2P receive antenna ports, and it includes an over-the-air OTA channel portion between the at least four probes and the terminal device. Apparatus 900 derives a virtual cable calibration matrix from the received channel representation for compensation of the OTA channel portion.

[0103] In an exemplary embodiment, the apparatus 900 may receive a channel representation from a terminal device in a user equipment assistance information message. The apparatus 900 may also include: a fifth component (not shown) for receiving a capability report from the terminal device, the capability report indicating a capability for supporting a channel estimation report for compensation of an OTA channel portion; and a sixth component (not shown) for sending a configuration for estimating a channel to the terminal device. The terminal device may send a channel representation to the apparatus 900 based on the received configuration for channel estimation.

[0104] In an exemplary embodiment, the apparatus 900 may receive a channel representation from the terminal device through a user equipment dedicated consistency test function. For example, the apparatus 900 may further include: a seventh component (not shown) for sending a user equipment consistency test command to the terminal device; and an eighth component (not shown) for receiving a user equipment consistency test response from the terminal device in response to the user equipment consistency test command, the user equipment consistency test response including the channel representation.

[0105] In an example embodiment, the channel representation received at the apparatus 900 may be encoded as a list of channel coefficients for the estimated channel, and the channel coefficients may include at least one of power, amplitude, and phase values.

[0106] In an example embodiment, the apparatus 900 may receive a channel representation from a terminal device using feedback of a type II codebook, an enhanced type II codebook, or another extension thereof, via a precoding matrix indicator PMI. For example, the apparatus 900 may include: a ninth component (not shown) for sending a channel state information reference signal to a terminal device as a training signal; a tenth component (not shown) for receiving a measurement report of a channel state information reference signal from a terminal device, the measurement report including: a PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof; an eleventh component (not shown) for deriving a virtual cable calibration matrix from the PMI; and a twelfth component for compensating an OTA channel portion using the virtual cable calibration matrix.

[0107] In an exemplary embodiment, the apparatus 900 may further include: a thirteenth component (not shown) for iterating the ninth component, the tenth component and the eleventh component to iteratively perform their operations to obtain a new virtual cable calibration matrix; a fourteenth component (not shown) for updating the virtual cable calibration matrix using the perturbation obtained from the new virtual cable calibration matrix; and a twelfth component for compensating the OTA channel portion using the updated virtual cable calibration matrix until the OTA channel portion is fully compensated.

[0108] In an exemplary embodiment, the apparatus 900 may further include a fifteenth component (not shown) for performing a user equipment conformance test after the apparatus 900 is calibrated (ie, after the OTA channel portion is fully compensated).

[0109] Fig.10 1 is a schematic block diagram illustrating a terminal device 1000 according to an example embodiment of the present disclosure. The terminal device 1000 may be implemented as the DUT 120 discussed above.

[0110] like Fig.10As shown in , the terminal device 1000 may include one or more processors 1011, one or more memories 1012, and one or more transceivers 1013 interconnected by one or more buses 1014. One or more buses 1014 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, an optical fiber, an optical device or other optical communication device, etc. Each of the one or more transceivers 1013 may include a receiver and a transmitter, which are connected to one or more antennas 1016. One or more antennas 1016 may include, for example, two dual-polarized antenna panels. The terminal device 1010 may wirelessly communicate with a radio access network via one or more antennas 1016. One or more memories 1012 may include instructions 1015, which, when executed by one or more processors 1011, may enable the terminal device 1000 to perform operations and processes related to the DUT 120 as described above.

[0111] Fig.11 1 is a schematic block diagram illustrating a test device 1100 according to an example embodiment of the present disclosure. The test device 1100 may be implemented as the test device 110 described above.

[0112] like Fig.11 As shown in , the test device 1100 may include one or more processors 1111, one or more memories 1112, and one or more transceivers 1113 interconnected by one or more buses 1114. The one or more buses 1114 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fibers, optical devices, or other optical communication devices. Each of the one or more transceivers 1113 may include a receiver and a transmitter, which are connected to one or more antennas 1116. The one or more antennas 1116 may include, for example, at least two dual-polarized antenna panels, which may be located at different locations within a test chamber (not shown), and each panel may include at least two probes. The test device 1100 may simulate the behavior of a base station, providing a plurality of probes to the base station. Fig.10 1000 sends a signal to the terminal device 1000 shown in . In an example embodiment, the test device 1100 may send multiple beams in different directions to the terminal device 1000 through one or more antennas 1116. The one or more memories 1112 may include instructions 1115, which, when executed by one or more processors 1111, may cause the test device 1100 to perform the operations and processes related to the test device 110 as described above.

[0113] The one or more processors 1011, 1111 may be any suitable type suitable for the local communication network, and may include a general-purpose processor, a dedicated processor, a microprocessor, a digital signal processor (DSP), one or more processors in a processor-based multi-core processor architecture, and a dedicated processor, such as those developed based on a field programmable gate array (FPGA) and an application-specific integrated circuit (ASIC). The one or more processors 1011, 1111 may be configured to control other elements of the terminal device / test equipment and operate in conjunction with them to implement the above process.

[0114] One or more memories 1012, 1112 may include at least one storage medium in various forms, such as transient memory and / or non-transient memory. Transient memory may include, but is not limited to, for example, random access memory (RAM) or cache. Non-transient memory may include, but is not limited to, for example, read-only memory (ROM), hard disk, flash memory, etc. The term "non-transient" used herein is a limitation of the medium itself (i.e., tangible, not a signal), rather than a limitation of data storage persistence (e.g., RAM vs. ROM). In addition, one or more memories 1012, 1112 may include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any combination thereof.

[0115] It should be understood that the blocks in the figure can be implemented in various ways, including software, hardware, firmware, or any combination thereof. In some embodiments, one or more blocks can be implemented using software and / or firmware, for example, machine executable instructions stored in a storage medium. In addition to or in place of machine executable instructions, some or all of the blocks in the figure can be implemented at least in part by one or more hardware logic components. Exemplary types of hardware logic components that can be used include, for example, but not limited to, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), etc.

[0116] Some exemplary embodiments also provide one or more program instructions, which, when executed by one or more processors, can enable equipment or devices to perform the above process. The program instructions for performing the process of exemplary embodiments can be written in any combination of one or more programming languages. The program instructions can be provided to one or more processors or controllers of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program instructions, when executed by a processor or controller, enable the function / operation specified in the flow chart and / or block diagram to be realized. The program instructions can be executed completely on the machine, partially on the machine, executed as an independent software package, partially on the machine, partially on a remote machine, or completely on a remote machine or server.

[0117] Some exemplary embodiments also provide a computer program product or a computer readable medium having one or more program instructions stored therein. A computer readable medium may be any tangible medium that may contain or store a program for use by or in connection with an instruction execution system, device, or apparatus. A machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination thereof. More specific examples of machine readable storage media include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0118] As used herein, “at least one of: ” and “at least one of ” and similar expressions (wherein a list of two or more elements is connected by “and” or “or”) mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0119] In addition, although the operations are shown in a specific order, it should not be understood that these operations are required to be performed in the specific order shown or in a sequential order, or that all the operations shown are required to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, they should not be interpreted as limitations on the scope of the present disclosure, but rather as descriptions of the features of specific embodiments. Certain features described in the context of separate embodiments may also be combined in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or implemented in any suitable sub-combination.

[0120] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims.

[0121] The embodiments of the present disclosure provide the following examples:

[0122] Example 1. A terminal device, comprising:

[0123] at least one processor; and

[0124] At least one memory, used to store instructions, which, when executed by the at least one processor, cause the terminal device to at least execute:

[0125] receiving a training signal from at least four probes, the terminal device and the at least four probes being located in a test room;

[0126] estimating a channel based on the received training signal, the channel comprising an over-the-air OTA channel portion between the at least four probes and the terminal device; and

[0127] A representation of the estimated channel is sent to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

[0128] Example 2. The terminal device according to Example 1, wherein the training signal is transmitted from 2P transmit antenna ports of the test device, and the training signal is received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1, and

[0129] The channel is a channel between 2P transmit antenna ports and 2P receive antenna ports.

[0130] Example 3. The terminal device of Example 1, wherein the channel representation is sent to the test device in a user equipment assistance information message.

[0131] Example 4. The terminal device according to Example 3, wherein the at least one memory further stores instructions, which when executed by the at least one processor, cause the terminal device to at least perform: before sending the channel representation to the test device:

[0132] Ability to report channel estimation reporting to the test equipment to support compensation for the OTA channel portion; and

[0133] A configuration for estimating the channel is received from the test equipment.

[0134] Example 5. A terminal device according to Example 1, wherein the channel representation is sent to the test device via a user equipment specific consistency test function.

[0135] Example 6. The terminal device according to Example 5, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the terminal device to at least execute:

[0136] receiving a user equipment conformance test command from a test device; and

[0137] In response to the user equipment consistency test command, a user equipment consistency test response is sent to the test device, where the user equipment consistency test response includes the channel representation.

[0138] Example 7. A terminal device according to any of Examples 3 to 6, wherein the channel representation is encoded as a list of channel coefficients for the channel, the channel coefficients comprising at least one of power, amplitude and phase values.

[0139] Example 8. The terminal device of Example 1, wherein the channel representation is sent to the test device via a precoding matrix indicator (PMI) feedback using a type II codebook, an enhanced type II codebook, or another extension thereof.

[0140] Example 9. The terminal device according to Example 8, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the terminal device to at least execute:

[0141] receiving a channel state information reference signal from a test device as the training signal;

[0142] A measurement report of the channel state information reference signal is sent to the test device, the measurement report including: a PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof, the PMI indicating a precoding matrix associated with the estimated channel.

[0143] Example 10. The terminal device according to Example 9, wherein the steps of receiving the channel state information reference signal and sending the measurement report are repeated until the OTA channel portion is fully compensated.

[0144] Example 11. A test device comprising:

[0145] at least one processor; and

[0146] At least one memory storing instructions, which when executed by the at least one processor, cause the test device to at least perform:

[0147] Sending a training signal to a terminal device through at least four probes, wherein the terminal device and the at least four probes are located in a test room;

[0148] receiving, from the terminal device, a representation of a channel estimated by the terminal device, the channel comprising a portion of an over-the-air OTA channel between the at least four probes and the terminal device;

[0149] deriving a virtual cable calibration matrix for compensation of the OTA channel portion from the channel representation; and

[0150] Use the virtual cable calibration matrix to compensate for the OTA channel portion.

[0151] Example 12. The test device according to Example 11, wherein the training signal is transmitted from 2P transmit antenna ports of the test device, and the training signal is received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1, and

[0152] The channel is a channel between 2P transmit antenna ports and 2P receive antenna ports.

[0153] Example 13. The test device of Example 11, wherein the channel representation is received from the terminal device in a user equipment assistance information message.

[0154] Example 14. The test device of Example 13, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the test device to at least perform: before receiving the channel representation from the terminal device:

[0155] receiving a capability report from the terminal device, the capability report indicating a capability to support channel estimation reporting for compensation of an OTA channel portion; and

[0156] A configuration for estimating the channel is sent to the terminal device.

[0157] Example 15. The test device of Example 11, wherein the channel representation is received from the terminal device via a user equipment-specific conformance test function.

[0158] Example 16. The test device of Example 15, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the test device to at least perform:

[0159] Sending a user equipment consistency test command to the terminal device; and

[0160] In response to the user equipment conformance test command, a user equipment conformance test response is received from the terminal device, the user equipment conformance test response including the channel representation.

[0161] Example 17. A terminal device according to any of Examples 13 to 16, wherein the channel representation is encoded as a list of channel coefficients for the channel, the channel coefficients comprising at least one of power, amplitude and phase values.

[0162] Example 18. The test device of Example 11, wherein the channel representation is received from the test device via precoding matrix indicator (PMI) feedback using a type II codebook, an enhanced type II codebook, or another extension thereof.

[0163] Example 19. The test device of Example 18, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the test device to at least perform:

[0164] Sending a channel state information reference signal to the terminal device as the training signal;

[0165] Receiving a measurement report of the channel state information reference signal from the terminal device, the measurement report comprising: a PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof;

[0166] deriving a virtual cable calibration matrix from the PMI; and

[0167] Use the virtual cable calibration matrix to compensate for the OTA channel portion.

[0168] Example 20. The test device of Example 19, wherein the at least one memory further stores instructions that, when executed by the at least one processor, cause the test device to at least: iterate through the following steps until the OTA channel portion is sufficiently compensated:

[0169] Sending a new channel state information reference signal to the terminal device as a new training signal;

[0170] Receiving a new measurement report of a new channel state information reference signal from the terminal device, the new measurement report comprising: a new PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof;

[0171] derive a new virtual cable calibration matrix from the new PMI;

[0172] updating the virtual cable calibration matrix using the perturbations obtained from the new virtual cable calibration matrix; and

[0173] The OTA channel portion is compensated using the updated virtual cable calibration matrix.

[0174] Example 21. A method comprising:

[0175] At a terminal device, receiving a training signal from at least four probes, the terminal device and the at least four probes being located in a test room;

[0176] estimating a channel based on the received training signal, the channel comprising an over-the-air OTA channel portion between the at least four probes and the terminal device; and

[0177] A representation of the estimated channel is sent to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

[0178] Example 22. The method according to Example 21, wherein the training signal is transmitted from 2P transmit antenna ports of the test device, and the training signal is received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1, and

[0179] The channel is a channel between 2P transmit antenna ports and 2P receive antenna ports.

[0180] Example 23. The method of Example 21, wherein the channel representation is sent to the test device in a user equipment assistance information message.

[0181] Example 24. The method of Example 23, further comprising: before sending the channel representation to the test device:

[0182] Ability to report channel estimation reporting to the test equipment to support compensation for the OTA channel portion; and

[0183] A configuration for estimating the channel is received from the test equipment.

[0184] Example 25. The method of Example 21, wherein the channel representation is sent to the test equipment via a user equipment specific conformance test function.

[0185] Example 26. The method according to Example 25, further comprising:

[0186] receiving a user equipment conformance test command from a test device; and

[0187] In response to the user equipment consistency test command, a user equipment consistency test response is sent to the test device, where the user equipment consistency test response includes the channel representation.

[0188] Example 27. A method according to any one of Examples 23 to 26, wherein the channel representation is encoded as a list of channel coefficients for the channel, the channel coefficients comprising at least one of power, amplitude, and phase values.

[0189] Example 28. The method of Example 21, wherein the channel representation is sent to the test device via precoding matrix indicator (PMI) feedback using a type II codebook, an enhanced type II codebook, or another extension thereof.

[0190] Example 29. The method according to Example 28, further comprising:

[0191] receiving a channel state information reference signal from a test device as the training signal;

[0192] A measurement report of the channel state information reference signal is sent to the test device, the measurement report including: a PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof, the PMI indicating a precoding matrix associated with the estimated channel.

[0193] Example 30. The method of Example 29, wherein the steps of receiving the channel state information reference signal and sending the measurement report are repeated until the OTA channel portion is fully compensated.

[0194] Example 31. A method comprising:

[0195] Sending a training signal to a terminal device through at least four probes, wherein the terminal device and the at least four probes are located in a test room;

[0196] receiving, from the terminal device, a representation of a channel estimated by the terminal device, the channel comprising a portion of an over-the-air OTA channel between the at least four probes and the terminal device;

[0197] deriving a virtual cable calibration matrix for compensation of the OTA channel portion from the channel representation; and

[0198] Use the virtual cable calibration matrix to compensate for the OTA channel portion.

[0199] Example 32. The method according to Example 31, wherein the training signal is transmitted from 2P transmit antenna ports of the test device, and the training signal is received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1, and

[0200] The channel is a channel between 2P transmit antenna ports and 2P receive antenna ports.

[0201] Example 33. The method of Example 31, wherein the channel representation is received from the terminal device in a user equipment assistance information message.

[0202] Example 34. The method of Example 33, further comprising: before receiving the channel representation from the terminal device:

[0203] receiving a capability report from the terminal device, the capability report indicating a capability to support channel estimation reporting for compensation of an OTA channel portion; and

[0204] A configuration for estimating the channel is sent to the terminal device.

[0205] Example 35. The method of Example 31, wherein the channel representation is received from the terminal device via a user equipment-specific conformance test function.

[0206] Example 36. The method according to Example 35, further comprising:

[0207] Sending a user equipment consistency test command to the terminal device; and

[0208] In response to the user equipment conformance test command, a user equipment conformance test response is received from the terminal device, the user equipment conformance test response including the channel representation.

[0209] Example 37. A method according to any one of Examples 33 to 36, wherein the channel representation is encoded as a list of channel coefficients for the channel, the channel coefficients comprising at least one of power, amplitude, and phase values.

[0210] Example 38. The method of Example 31, wherein the channel representation is received from the test device via precoding matrix indicator (PMI) feedback using a type II codebook, an enhanced type II codebook, or another extension thereof.

[0211] Example 39. The method of Example 38, further comprising:

[0212] Sending a channel state information reference signal to the terminal device as the training signal;

[0213] Receiving a measurement report of the channel state information reference signal from the terminal device, the measurement report comprising: a PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof;

[0214] deriving a virtual cable calibration matrix from the PMI; and

[0215] Use the virtual cable calibration matrix to compensate for the OTA channel portion.

[0216] Example 40. The method of Example 39, further comprising iterating through the following steps until the OTA channel portion is sufficiently compensated:

[0217] Sending a new channel state information reference signal to the terminal device as a new training signal;

[0218] Receiving a new measurement report of a new channel state information reference signal from the terminal device, the new measurement report comprising: a new PMI determined based on a type II codebook, an enhanced type II codebook, or another extension thereof;

[0219] derive a new virtual cable calibration matrix from the new PMI;

[0220] updating the virtual cable calibration matrix using the perturbations obtained from the new virtual cable calibration matrix; and

[0221] The OTA channel portion is compensated using the updated virtual cable calibration matrix.

[0222] Example 41. An apparatus comprising:

[0223] means for receiving training signals from at least four probes, the apparatus and the at least four probes being located in a test chamber;

[0224] means for estimating a channel based on the received training signal, the channel comprising an over-the-air OTA channel portion between the at least four probes and the device; and

[0225] Means for transmitting a representation of the estimated channel to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

[0226] Example 42. An apparatus comprising:

[0227] A component for sending a training signal to a terminal device through at least four probes, the terminal device and the at least four probes being located in a test chamber;

[0228] means for receiving, from the terminal device, a representation of a channel estimated by the terminal device, the channel comprising a portion of an over-the-air OTA channel between the at least four probes and the terminal device;

[0229] means for deriving a virtual cable calibration matrix for compensation of the OTA channel portion from the channel representation; and

[0230] Means for compensating for portions of the OTA channel using a virtual cable calibration matrix.

[0231] Example 43. A computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to at least perform:

[0232] receiving training signals from at least four probes, the apparatus and the at least four probes being located in a test chamber;

[0233] estimating a channel based on the received training signal, the channel comprising an over-the-air (OTA) channel portion between the at least four probes and the device; and

[0234] A representation of the estimated channel is sent to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

[0235] Example 44. A computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to at least perform:

[0236] Sending a training signal to a terminal device through at least four probes, wherein the terminal device and the at least four probes are located in a test room;

[0237] receiving, from the terminal device, a representation of a channel estimated by the terminal device, the channel comprising a portion of an over-the-air OTA channel between the at least four probes and the terminal device;

[0238] deriving a virtual cable calibration matrix for compensation of the OTA channel portion from the channel representation; and

[0239] Use the virtual cable calibration matrix to compensate for the OTA channel portion.

Claims

1. A terminal device, comprising: at least one processor; as well as At least one memory, for storing instructions, which, when executed by the at least one processor, cause the terminal device to at least perform: receiving a training signal from at least four probes, the terminal device and the at least four probes being located in a test room; estimating a channel based on the received training signal, the channel comprising an over-the-air OTA channel portion between the at least four probes and the terminal device; as well as The estimated representation of the channel is sent to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

2. The terminal device according to claim 1, wherein the training signal is transmitted from 2P transmit antenna ports of the test device, and the training signal is received at 2P receive antenna ports of the terminal device, where P is an integer greater than 1, and The channel is a channel between the 2P transmitting antenna ports and the 2P receiving antenna ports.

3. The terminal device according to claim 1, wherein the channel representation is sent to the test device in a User Equipment Assistance Information message.

4. The terminal device according to claim 3, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the terminal device to at least perform: before sending the channel representation to the test device: reporting to the test equipment a capability to support channel estimation reporting for compensation of the OTA channel portion; and A configuration for estimating the channel is received from the test equipment.

5. The terminal device according to claim 1, wherein the channel representation is sent to the test device through a user equipment specific conformance test function.

6. The terminal device according to claim 5, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the terminal device to at least execute: receiving a user equipment conformance test command from the test device; and In response to the user equipment consistency test command, a user equipment consistency test response is sent to the test device, where the user equipment consistency test response includes the channel representation.

7. A terminal device according to any one of claims 3 to 6, wherein the channel representation is encoded as a list of channel coefficients for the channel, the channel coefficients comprising at least one of power, amplitude and phase values.

8. The terminal device of claim 1, wherein the channel representation is sent to the test device via a precoding matrix indicator (PMI) feedback using a type II codebook, an enhanced type II codebook, or another extension thereof.

9. The terminal device according to claim 8, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the terminal device to at least execute: receiving a channel state information reference signal from the test device as the training signal; Sending a measurement report of the channel state information reference signal to the test device, the measurement report comprising: A PMI determined based on the type-II codebook, the enhanced type-II codebook, or the further extension thereof, the PMI indicating a precoding matrix associated with the estimated channel.

10. A method for communication, comprising: At a terminal device, receiving a training signal from at least four probes, the terminal device and the at least four probes being located in a test room; estimating a channel based on the received training signal, the channel comprising an over-the-air OTA channel portion between the at least four probes and the terminal device; as well as The estimated representation of the channel is sent to a test device coupled to the at least four probes for use in compensation of the OTA channel portion.

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