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Title:
APPARATUS AND METHOD FOR USE IN A CHARACTERIZATION OF A WIRELESS COMMUNICATION COMPONENT/SYSTEM/NETWORK, SYSTEM FOR CHARACTERIZING A WIRELESS COMMUNICATION COMPONENT/SYSTEM/NETWORK AND WIRELESS COMMUNICATION COMPONENT AND METHOD FOR CHARACTERIZING A WIRELESS COMMUNICATION COMPONENT USING A DETERMINATION OF PERTURBATION
Document Type and Number:
WIPO Patent Application WO/2019/002221
Kind Code:
A1
Abstract:
An apparatus for use in a characterization of a wireless communication system or/and component or/and network in a measurement environment, wherein the apparatus is configured to determine a perturbation of a measurement environment based on one or more observation antenna signals.

Inventors:
ASKAR RAMEZ (DE)
LEATHER PAUL SIMON HOLT (DE)
SAKAGUCHI KEI (DE)
HAUSTEIN THOMAS (DE)
KEUSGEN WILHELM (DE)
Application Number:
PCT/EP2018/066989
Publication Date:
January 03, 2019
Filing Date:
June 25, 2018
Export Citation:
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Assignee:
FRAUNHOFER GES FORSCHUNG (DE)
International Classes:
H04B17/21; G01R29/08; H04B17/345
Domestic Patent References:
WO2003056349A12003-07-10
WO2016178778A12016-11-10
WO2017008851A12017-01-19
Foreign References:
EP17173796A2017-05-31
US20060055592A12006-03-16
Other References:
"Measurement of radiated performance for Multiple Input Multiple Output (MIMO) and multi-antenna reception for High Speed Packet Access (HSPA) and LTE terminals (Release 13", 3RD GENERATION PARTNERSHIP PROJECT (3GPP), TR 37.976, 2016
R. ASKAR; T. KAISER; B. SCHUBERT; T. HAUSTEIN; W. KEUSGEN: "Active self-interference cancellation mechanism for full-duplex wireless transceivers", COGNITIVE RADIO ORIENTED WIRELESS NETWORKS AND COMMUNICATIONS (CROWNCOM), 2014 9TH INTERNATIONAL CONFERENCE, 2014
R. ASKAR; B. SCHUBERT; W. KEUSGEN; T. HAUSTEIN: "Agile Full-Duplex Transceiver: The Concept and Self-Interference Channel Characteristics", EUROPEAN WIRELESS 2016; 22TH EUROPEAN WIRELESS CONFERENCE, 2016
R. ASKAR; B. SCHUBERT; W. KEUSGEN; T. HAUSTEIN: "Full-Duplex Wireless Transceiver in Presence of I/Q Mismatches: Experimentation and Estimation Algorithm", IEEE GC 2015 WORKSHOP ON EMERGING TECHNOLOGIES FOR 5G WIRELESS CELLULAR NETWORKS - 4TH INTERNATIONAL (GC'15 - WORKSHOP - ET5G), 2015
R. ASKAR; N. ZARIFEH; B. SCHUBERT; W. KEUSGEN; T. KAISER: "I/O imbalance calibration for higher self-interference cancellation levels in Full-Duplex wireless transceivers", 5G FOR UBIQUITOUS CONNECTIVITY (5GU), 2014 1ST INTERNATIONAL CONFERENCE, 2014
P.S.H. LEATHER; J.D. PARSONS: "Equalization for antenna pattern measurements: established technique - new application", IEEE ANTENNAS PROPAG. MAG., vol. 45, no. 2, 2003, pages 154 - 161
Attorney, Agent or Firm:
BURGER, Markus et al. (DE)
Download PDF:
Claims:
Claims

An apparatus (100; 210; 310) for use in a characterization of a wireless communication system (230) or/and wireless communication component (230) or/and wireless communication network (230) in a measurement environment (560), wherein the apparatus is configured to determine (1 10) a perturbation of a measurement environment based on one or more observation antenna signals (101 ).

An apparatus according to claim 1 , wherein the apparatus is configured to determine perturbations which are based on geometric changes of the

measurement environment.

An apparatus according to claim 1 or claim 2, wherein the apparatus is configured to detect the perturbation, wherein determining the perturbation comprises determining a change of a propagation characteristic.

An apparatus according to claim 2 or 3, wherein the apparatus is configured to determine if a change of one or more of the observation antenna signals goes beyond a change of the one or more observation signals caused by an emulation of a multipath propagation, and wherein the apparatus is configured to detect a perturbation in dependence on the determination.

An apparatus according to one of the claims 1 to 4, wherein the apparatus is configured to determine perturbations based on an interfering source (610) signal, which is included in the one or more observation antenna signals.

An apparatus according to one of the claims 1 to 5, wherein the apparatus is configured to determine perturbations in a frequency band of the one or more observation antenna signals.

7. An apparatus according to one of the claims 1 to 6, wherein the apparatus is

configured to at least partially compensate contributions of known test signals, used for characterization of the wireless communication component/system, which are included in the one or more observation antenna signals.

8. An apparatus according claim 7, wherein the apparatus is configured to filter the known test signals using channel estimates of one or more channels among one or more antennas (31 1 ; 51 1 ) receiving the one or more observation antenna signals and one or more antennas (323; 523; 230; 340) from which the test signals are transmitted, and to at least partially cancel the filtered test signal from the one or more observation antenna signals.

9. An apparatus according to claim 8, wherein the apparatus is configured to update the channel estimates, in response to a determination of a perturbation which is based on a change of a geometry of the measurement environment.

10. An apparatus according to one of the claims 1 to 10, wherein the apparatus is configured to determine a perturbation using test signals which are used for a characterization of the wireless communication component/system/network.

1 1 . An apparatus according to one of the claims 2 to 10, wherein the apparatus is configured to determine whether a perturbation is due to a change of a geometry of the measurement environment or an interfering source based on a correlation.

12. An apparatus according to claim 1 1 , wherein the apparatus is configured to

recognize a change of a geometry of the measurement environment when the apparatus finds a comparatively higher correlation between the one or more observation antenna signals, or a processed version thereof, and test signals, and/or wherein the apparatus is configured to recognize an interfering source (610) causing the perturbation when the apparatus finds a comparatively lower correlation between the one or more observation antenna signals, or a processed version thereof, and the test signals.

13. An apparatus according to one of the claims 1 to 12, wherein the apparatus

comprises one or more measurement antennas (323; 523), and one or more observation antennas (31 1 ; 51 1 ), wherein the apparatus is configured to perform a characterization of the wireless communication com ponent/system/network using the one or more measurement antennas, and wherein the apparatus is configured to determine a perturbation of the measurement environment using the one or more observation antennas.

An apparatus according to one of the claims 1 to 13, wherein the apparatus is configured to determine a perturbation due to a change of a geometry of the measurement environment, and wherein the apparatus is configured to trigger an estimation of an up-to-date channel information, which is used in the characterization of the wireless communication component/system/network, based on the determination.

An apparatus according to one of the claims 1 to 14, wherein the apparatus is configured to determine a perturbation based on a power detection of a received signal of the apparatus, such that a perturbation is indicated when a power of the received signal exceeds a predefined threshold.

An apparatus according to one of the claims 1 to 15, wherein the apparatus is configured to determine a perturbation based on a power detection of a received signal of observation antennas or based on a determination by an observation antenna receiver.

An apparatus according to claim 15 or 16, wherein the apparatus is configured to estimate or re-estimate a channel information when a detected power exceeds a predefined threshold.

An apparatus according to one of claims 1 to 17, wherein the apparatus is configured to mark a measurement as compromised when a perturbation is detected. An apparatus according to one of the claims 1 to 18, wherein the apparatus is configured to obtain a knowledge on disturbances which disrupt a measurement fidelity.

An apparatus according to one of the claims 1 to 19, wherein the apparatus is configured to provide an interference estimate to a device under test (230; 340; 540), wherein the interference estimate is usable for an interference compensation at the device under test.

An apparatus according to one of the claims 1 to 20, wherein the apparatus is configured to provide an interference estimate to a measurement apparatus (220; 420), wherein the interference estimate is usable for an interference compensation at the measurement apparatus.

A system (200; 300; 400; 500) for characterizing a wireless communication component/system/network comprising an apparatus (100; 210; 310) for use in a characterization of a wireless

communication component/system/network according to one of the claims 1 to 21 , and an apparatus (220; 320; 420) for characterizing a wireless communication component/system/network, wherein the apparatus for use in a characterization of a wireless communication component/system/network is configured to provide measurement observation information (341 ) to the apparatus for characterizing a wireless communication component/system/network.

A system according to claim 22, wherein the apparatus for characterizing a wireless component/system/network is configured to filter a transmit signal using pre-equalization filter, such that an effect of multipath propagation at the wireless communication component is at least partially compensated, and/or such that a multipath propagation is emulated, and wherein the apparatus (100; 210; 310) for use in a characterization of a wireless communication component/system/network is configured to provide information to update the pre-equalization filter in response to a determination of a perturbation.

A system according to claim 22 or 23, wherein the apparatus for characterizing a wireless component/system/n etwo rk is configured to filter a receive signal with an equalization filter, such that an effect of multipath propagation between the wireless communication component and measurement antennas of the system is at least partially compensated, and/or such that a multipath propagation is emulated, and wherein the apparatus (100; 210; 310) for use in a characterization of a wireless communication component/system/network is configured to provide information to update the equalization filter in response to a determination of a perturbation.

A system according to one of the claims 22 to 24, wherein the system is configured to recalibrate a channel information utilizing knowledge about signals which are simultaneously used for a characterization of the wireless communication component/system/network, in response to a determination of a perturbation by the apparatus (100; 210; 310) for use in a characterization of a wireless communication component/system/network.

A system according to one of the claims 22 to 25, wherein the system is configured to provide a measurement of the wireless communication component based on a correction of received test signals, after a transmission of the test signals.

A system according to one of the claims 22 to 26, wherein the system is configured to determine a change of a location of an object (562; 564) in the measurement environment based on a detected perturbation.

A system according to one of the claims 22 to 27, wherein the system is configured to recalibrate a channel information utilizing knowledge about signals which are simultaneously used for a characterization of the wireless communication component/system/network, upon determination of a change of a geometry of the measurement environment. A system according to one of the claims 22 to 28, wherein the apparatus for use in a characterization of a wireless communication component/system/network is configured to at least partially compensate (313) a contribution of a test signal in an observation antenna signal, wherein the test signal is emitted by the apparatus for characterizing a wireless communication component/system/network or by the wireless communication component/system/network.

A wireless communication component (700), wherein the wireless communication component is configured to obtain an interference signal estimate (701 ) via a control channel (702), when the wireless communication component is in a characterization mode, and wherein the wireless communication component is configured to at least partially compensate an interference signal which is included in a received signal (703) based on the interference signal estimate.

A wireless communication component according to claim 30, wherein the interference signal is caused by an interfering source in a measurement environment.

Method (800) for use in a characterization of a wireless communication component/system/network in a measurement environment, comprising

Determining (810) a perturbation of a measurement environment based on one or more observation antenna signals.

Method (900) for characterizing a wireless communication component, comprising obtaining (910) an interference signal estimate via a control channel, when the wireless communication component is in a characterization mode, and at least partially compensating (920) an interference signal which is included in a received signal based on the interference signal estimate. Computer program with a program code for performing one of the methods 32 or 33, when the computer program runs on a computer or a microcontroller.

Description:
Apparatus and method for use in a characterization of a wireless communication component/system/network, System for characterizing a wireless communication component/system/network and wireless communication component and method for characterizing a wireless communication component using a determination of perturbation

Description

Embodiments of the present invention generally relate to characterization of wireless communication components and/or systems and/or networks. Embodiments according to the invention are related to a system that observes and corrects environmental changes in a characterization of such devices.

Background of thj lnvgntign

Performing over-the-air (OTA) measurements in non-anechoic environments will lead to a major reduction in building costs, as the need for the construction of an anechoic chamber becomes unnecessary. This will ease the entire OTA measurement procedure and make it possible for such measurements to be performed almost anywhere, irrespective of the surrounding environment.

Currently, OTA measurements take place in specially constructed surroundings such as multi-probe anechoic chambers (MPAC) or reverberation chambers [1], This is to create controlled multipath environments.

Presently, three main types of OTA measurement environments are proposed for standardization; the multi-probe anechoic chamber (MPAC), the compact antenna test range (CATR), and the reverberation chamber (RC) [1 ]. In a typical OTA measurement setup, the device under test (DUT), probes and the environment in which they reside, are arranged in such a way that the effects of multi-path reflection are eliminated or, at least reduced to a required level. This is in order to ensure measurement repeatability. All state- of-the-art solutions have thus considered OTA measurement setups that take place in controlled environments. Therefore, a desire exists for an improved concept which enables a better, e.g. more flexible or reliable, characterization of wireless communication components and/or systems and/or networks. Summary of the Invention

An embodiment according to the invention provides an apparatus for use in a characterization of a wireless communication system or/and of a wireless communication component or/and of a wireless communication network in a measurement environment. The apparatus is configured to determine a perturbation of a measurement environment based on one or more observation antenna signals. The wireless communication component may, for example, be a mobile phone or a radio system of a mobile phone. The wireless communication system may, for example, comprise one or more base stations and one or more mobile phones. The wireless communication network may, for example, comprise one or more base stations and one or more mobile phones and one or more control servers.

The described apparatus is based on the idea that, when performing measurements for characterization of the wireless communication system or/and component or/and network, it is beneficial to determine (or detect) if a perturbation of the measurement environment is occurring. The apparatus may for example indicate to a further measurement equipment (or to a further component of the apparatus) that the perturbation has been determined and an appropriate reaction can be performed by the further measurement equipment(or by the further component of the apparatus). The further measurement equipment (or the further component of the apparatus) may, for example, counteract the perturbation or label the measurement as compromised, based on the determination. Thus, it is possible to perform measurements in environments which are prone to perturbations (e.g. to a change of channel characteristics or to the presence of perturbing radio sources), which brings along an improved flexibility.

According to embodiments, the apparatus may be configured to determine perturbations which are based on geometric changes of the measurement environment. Having the ability to detect geometric changes enables the ability to report, or/and provide appropriate countermeasures, e.g., reporting changes occurrence in the surrounding environment, or/and retraining of a geometric model of the measurement environment. Furthermore, a geometric change leads, in general, to a changed channel impulse response. When a system uses compensation of the channel impulse response it is helpful for the system to know of changes about the channel impulse response.

According to embodiments, the apparatus may be configured to detect the perturbation, wherein determining the perturbation comprises determining a change of a propagation characteristic. Determining the change of a propagation characteristic can be helpful, as it indicates a change of the measurement environment, which may influence the characterization. According to embodiments, the apparatus may be configured to determine if a change of one or more of the observation antenna signals goes beyond a change of the one or more observation signals caused by an emulation of a multipath propagation. Moreover, the apparatus may be configured to detect a perturbation in dependence on the determination. The described embodiment may be useful in distinguishing wanted from unwanted changes of the received signal characteristics, wherein the wanted changes in the received signal characteristics (which may be caused by a change of a configuration of a measurement apparatus, for example, by an intentional application of a channel impulse response filtering in a transmitter) may be useful for a characterization of the wireless communication component/system/network.

According to embodiments, the apparatus may be configured to determine perturbations based on an interfering source signal, which is included in the one or more observation antenna signals. The described embodiment is beneficial, for detecting an interfering source which may be active in the measurement environment. Knowledge about an interference can be helpful to grade a reliability of the characterization or to take countermeasures.

According to embodiments, the apparatus may be configured to determine perturbations in a frequency band or multiple bands of the one or more observation antenna signals. The described embodiment may observe only frequency bands which are used for the characterization, however, it may also be able to observe further frequency bands. Thereby, changes in other frequency bands may occur but do not influence the characterization and may be negligible. According to embodiments, the apparatus may be configured to at least partially compensate contributions of known test signals, used for characterization of the wireless communication component/system, which are included in the one or more observation antenna signals. The described embodiment may observe a characterization while not being hampered by test signals, which are basically desired signals. Thereby, the apparatus may focus on disturbances due to other sources, which are not wanted and, in general, emit signals different from the test signals.

According to embodiments, the apparatus may be configured to filter the known test signals using channel estimates of one or more channels among one or more antennas receiving the one or more observation antenna signals and one or more antennas from which the test signals are transmitted. Further, the embodiment may be configured to at least partially cancel the filtered test signal from the one or more observation antenna signals. The described embodiment is helpful in determining an unwanted interference, as desired signals do not hamper a detection of unwanted interference. Specifically, the test signals may be filtered with estimated channel impulse responses, to obtain an estimate of contributions of the test signals to the one or more observation antenna signals. Thus, a residual signal, which remains after the cancellation, is used as an indication whether there is another disturbing source or whether channel characteristics have changed.

According to embodiments, the apparatus may be configured to update the channel estimates or/and report a channel change update, in response to a determination of a perturbation which is based on a change of a geometry of the measurement environment. Having an updated channel estimate enables a determination of perturbations substantially free of influences from the test signals, as an influence of the test signals can be removed at the observation antennas.

According to embodiments, the apparatus may be configured to determine a perturbation, e.g. of a channel between observation antennas and characterization antennas, using test signals which are used for a characterization of the wireless communication component/system/network. The described embodiment can flexibly allow an observation of a channel between characterization antennas and observation antennas, e.g. using known test signals.

According to embodiments, the apparatus may be configured to determine whether a perturbation is due to a change of a geometry of the measurement environment or an interfering source based on a correlation. The described embodiment can flexibly determine a cause for a perturbation and initiate an appropriate reaction by a characterization system.

According to embodiments, the apparatus may be configured to recognize a change of a geometry of the measurement environment when the apparatus finds a comparatively higher correlation between the one or more observation antenna signals, or a processed version thereof (for example, a version in which test signals are at least partially cancelled or compensated), and test signals. Alternatively or additionally, the apparatus may be configured to recognize an interfering source causing the perturbation when the apparatus finds a comparatively lower correlation between the one or more observation antenna signals, or a processed version thereof, and the test signals. The use of a correlation enables a simple and efficient method to determine a cause of a perturbation. For example, when a room geometry changes, a larger contribution of the test signals leaks into the processed observation antenna signals, which is correlated to the test signals, and thereby can be easily identified using correlation.

According to embodiments, the apparatus may comprise one or more measurement antennas and one or more observation antennas. Moreover, the apparatus may be configured to perform a characterization of the wireless communication component/system/network using the one or more measurement antennas. Further, the apparatus may be configured to determine a perturbation of the measurement environment using the one or more observation antennas. Having separate observation antennas allows for higher flexibility as they can be positioned in a suitable position for observation. However, it should be noted that separate observation antennas are not necessary in some embodiments, as the observation antenna signals may also be obtained from the same antennas, which are used for measurement/characterization of the wireless communication component/system/network.

According to embodiments, the apparatus may be configured to determine a perturbation due to a change of a geometry of the measurement environment. Further, the apparatus may be configured to trigger an estimation of an up-to-date channel information, which is used in the characterization of the wireless communication component/system/network, based on the determination. When a geometry of the measurement changes, in general, a channel impulse response, between transmit and receive antennas will also change. Due to the change a formerly channel estimate may be insufficient in compensating contribution of the test signals. Therefore, updating the channel information allows for up- to-date compensation of undesired multipath-propagation effect between the DUT and an antenna used for characterization of the DUT (i.e. wireless communication component/system/network). The updated channel information may, for example, be used in a pre-equalization, e.g. using a linear model, of signals transmitted to the DUT, or in an equalization of signals received from the DUT.

According to embodiments, the apparatus may be configured to determine a perturbation based on a power detection of a received signal of the apparatus, such that a perturbation is indicated when a power of the received signal exceeds a predefined threshold. The described embodiment can, in general, detect perturbations based on a change of a power of the received signal, e.g. after contributions of test signals have been at least partially compensated.

According to embodiments, the apparatus may be configured to determine a perturbation based on a power detection of a received signal of observation antennas or based on a determination by an observation antenna receiver. The described embodiment may flexibly use directly the observation antenna signals or a power detection performed in an observation antenna receiver for performing the power detection. Thus, it is not necessary to use the signals of the measurement antennas.

According to embodiments, the apparatus may be configured to trigger an estimate or re- estimate a channel information when a detected power exceeds a predefined threshold. The described embodiment allows, e.g., for a recalibration of a characterization equipment, used for characterizing the wireless communication component/system/network. Alternatively, or in addition, it may also estimate or re- estimate a channel information used for the observation of the characterization.

According to embodiments, the apparatus may be configured to report a detected power to an apparatus for characterization of the wireless communication component/system/network, e.g. a recalibration and correction unit of the apparatus for characterization of the wireless communication component/system/network. Further, the detection unit may be configured to estimate a channel information when the detected power exceeds a predefined threshold. According to embodiments, the apparatus may be configured to mark a measurement as compromised when a perturbation is detected. The described embodiment allows for providing a side information for a measurement, which indicates the quality of the measurement.

According to embodiments, the apparatus may be configured to report a determined perturbation to an apparatus for characterization of the wireless communication component/system/network, e.g. a performance evaluation unit of the apparatus for characterization of the wireless communication component/system/network, wherein the apparatus for characterization of the wireless communication component/system/network may be configured to mark a measurement as compromised when a perturbation is detected.

According to embodiments, the apparatus may be configured to obtain a knowledge on disturbances which disrupt a measurement fidelity. The described embodiment may determine a disturbance based on an interfering source or a change of geometry, which would block the measurement fidelity. This can be avoided by the described embodiment by usage of the knowledge of the disturbance.

According to embodiments, the apparatus may be configured to provide an interference estimate to a device under test, wherein the interference estimate is usable for an interference compensation at the device under test. Thereby, an interference, e.g. caused by an interfering source, can at least partially be compensated at a signal used for characterization of the wireless communication component/system/network.

According to embodiments, the apparatus may be configured to provide an interference estimate to a measurement apparatus, wherein the interference estimate is usable for an interference compensation at the measurement apparatus. The described embodiment allows for a characterization of the wireless communication component/system/network even in the presence of interference. Embodiments provide for a system for characterizing a wireless communication component/system/network comprising an apparatus for use in a characterization of a wireless communication component/system/network according to one of the aforementioned embodiments and an apparatus for characterizing a wireless communication component/system/network. Moreover the apparatus for use in a characterization of a wireless communication component/system/network may be configured to provide measurement observation information to the apparatus for characterizing a wireless communication component/system/network. Thus, a configuration of the apparatus for characterization of a wireless communication component/system/network can be adapted in response to a detection of a perturbation, and a falsification of measurements can be avoided or reduced or at least recognized.

According to embodiments, the apparatus for characterizing a wireless component/system/network may be configured to filter a transmit signal using a pre- equalization filter, such that an effect of multipath propagation at the wireless communication component is at least partially pre-compensated, and/or such that a multipath propagation is emulated. Further, the apparatus for use in a characterization of a wireless communication component/system/network may be configured to provide information to update the pre-equalization filter in response to a determination of a perturbation. The described embodiment allows for a flexible compensation of unwanted multipath propagation effects by conditioning of the transmit signal. This filtering may, for example, be adapted in response to a recognition of a perturbation of a channel.

According to embodiments, the apparatus for characterizing a wireless component/system/network may be configured to filter a receive signal with an equalization filter, such that an effect of multipath propagation between the wireless communication component and measurement antennas of the system is at least partially compensated, and/or such that a multipath propagation is emulated. Further, the apparatus for use in a characterization of a wireless communication component/system/network may be configured to provide information to update the equalization filter in response to a determination of a perturbation. The described embodiment allows for a flexible compensation of unwanted multipath propagation effects by conditioning of the received signal. This filtering may, for example, be adapted in response to a recognition of a perturbation of a channel.

According to embodiments, the system may be configured to recalibrate for a channel information (for example, a channel information used to adjust a filtering of the transmit signal or a filtering of the received signal) utilizing knowledge about signals, e.g. test signals, which are simultaneously used for a characterization of the wireless communication component/system/network, in response to a determination of a perturbation by the apparatus for use in a characterization of a wireless communication component/system/network. By usage of knowledge of employed test signals, an at least partial compensation of contributions of the test signals to the one or more observation antennas signals can be easily performed. In other words, the channel information can be easily updated or/and then recalibrated using known signals used for characterization of the wireless communication component/system/network. According to embodiments, the system may be configured to provide a measurement of the wireless communication component/system/network based on a correction of received test signals, after a transmission of the test signals. The described embodiment allows for characterization of the wireless communication component/system/network based on a corrected received test signal, which more accurately describes the wireless communication component/system/network, e.g. substantially free of perturbations based on interference or unwanted multipath propagation effects.

According to embodiments, the system may be configured to determine a change of a location of an object in the measurement environment based on a detected perturbation. The described embodiment may flexibly observe a measurement environment, e.g. such that geometrical changes of the measurement environment can be easily recorded or compensated.

According to embodiments, the system may be configured to update on a channel information or/and then recalibrate utilizing knowledge about signals which are simultaneously used for a characterization of the wireless communication component/system/network, upon determination of a change of a geometry of the measurement environment. The described embodiment allows for the system to flexibly react to changes of a geometry of the measurement environment.

According to embodiments, the apparatus for use in a characterization of a wireless communication component/system/network may be configured to at least partially compensate a contribution of a test signal in an observation antenna signal, wherein the test signal is emitted by the apparatus for characterizing a wireless communication component/system/network or the wireless communication component/system/network. The described system can independent from test signals observe a measurement environment.

Embodiments according to the invention provide a wireless communication component. The wireless communication component may be configured to obtain an interference signal estimate via a control channel, when the wireless communication component is in a characterization mode. Moreover, the wireless communication component may be configured to at least partially compensate an interference signal which is included in a received signal based on the interference signal estimate. The wireless communication component may be a mobile phone which is able to be set in a characterization mode and remove known test signals to, e.g. allow for a compensation of perturbations of the test environment, e.g. multipath effects or disturbances of external sources.

According to embodiments, the interference signal may be caused by an interfering source in a measurement environment. The described embodiment can flexibly remove or at least partially compensate interference caused by an extraneous interferer.

Embodiments according to the invention provide for a method for use in a characterization of a wireless communication component/system/network in a measurement environment, comprising determining a perturbation of a measurement environment based on one or more observation antenna signals.

Embodiments according to the invention provide for a method that allow characterizing a wireless communication component, comprising obtaining an interference signal estimate via a control channel, when the wireless communication component is in a characterization mode. Moreover, the method may comprise at least partially compensating an interference signal which is included in a received signal based on the interference signal estimate

The described methods can be supplemented by any of the features or functionalities described herein with apparatuses, either individually or in combination.

A further preferred embodiment of the invention is a computer program with a program code for performing one of the aforementioned methods when the computer program runs on a computer or a microcontroller.

Brief Description of the Figures

In the following, embodiments of the present invention will be explained with reference to the accompanying drawings, in which: Fig. 1 shows a schematic block diagram of an apparatus according to embodiments of the invention;

Fig. 2 shows a schematic block diagram of a system according to embodiments of the invention;

Fig. 3 shows a schematic block diagram of a system according to embodiments of the invention in a downlink configuration; Fig. 4a shows a schematic block diagram of a system according to embodiments of the invention in an uplink configuration;

Fig. 4b shows a schematic block diagram of a system according to embodiments of the invention in a combined uplink and downlink configuration;

Fig. 5 shows a schematic of a measurement scenario in a first time step according to embodiments of the invention;

Fig. 6 shows a schematic of a measurement scenario in a second time step according to embodiments of the invention;

Fig. 7 shows a schematic block diagram of a wireless communication component according to embodiments of the invention; Fig. 8 shows a flow chart of a method according to embodiments of the invention;

Fig. 9 shows a flow chart of a method according to embodiments of the invention.

Detailed Description of the Embodiments

Fig. 1 shows a schematic block diagram of an apparatus 100 according to embodiments of the invention. The apparatus 100 for use in a characterization of a wireless communication component/system/network is configured to determine a perturbation of a measurement environment based on one or more observation antenna signals 101. For example, using perturbation determiner 1 10. The features and functionalities of apparatus 100 will be described in more detail in context of the systems 200, 300, 400, 500 and 600 in Figs. 2-6. Moreover, apparatus 100 of Fig. 1 can be supplemented by any of the features and functionalities described herein, either individually or in combination.

Fig. 2 shows a schematic block diagram of a system 200 according to embodiments of the invention. The system 200 for characterizing a wireless communication component/system/network comprises an apparatus 210 for use in a characterization of a wireless communication component/system/network, e.g. apparatus 100, and an apparatus 220 for characterizing a wireless communication component/system/network. Further, a device under test (DUT) 230, e.g. a wireless communication component/system/network, can be characterized by the system 200. Moreover, the apparatus 210 for use in a characterization of a wireless communication component/system/network is configured to provide measurement observation information to the apparatus for characterizing a wireless communication component/system/network.

The apparatus 210 can for example detect or determine if an interfering source is active in the measurement environment and report the activity. Moreover, the apparatus 210 may be able to provide an estimate of the interference to the apparatus 220, which may be able to compensate an influence of the interference on a characterization, based on the interference estimate. Alternatively or in addition, the apparatus 210 may be able to detect a change of a geometry of the measurement environment, leading to a changed channel impulse response between measurement antennas and a device under test. Upon detection, the detection may be reported to apparatus 220 or directly used to initiate an re- estimation of a channel impulse response in the apparatus 220 or in the device under test 230.

Fig. 3 shows a schematic block diagram of a system 300 according to embodiments of the invention in a downlink configuration. The system 300 comprises an apparatus 310 for use in a characterization of a wireless communication component/system/network, an apparatus for characterizing a wireless communication component/system/network 320, a performance evaluation unit 330. Furthermore, a DUT 340, e.g. a wireless communication component/system/network, is set up for characterization in a downlink configuration, i.e. signals are being transmitted from the system 300 to the DUT 340. The apparatus 310, as a further embodiment of apparatus 100, may comprise observation antennas 31 1 , which are each connected to individual receivers 312. Moreover, the apparatus 310 may comprise an interference cancellation unit 313, which uses test signals provided by the apparatus 320, to at least partially remove contributions of the test signals onto the observation antenna signals. For that purpose, the interference cancellation unit 313 may be calibrated initially and recalibrated upon changes of the measurement environment. Furthermore, the apparatus 320 may comprise a signal integrity detection unit 314 which is provided with the observation antenna signals, after removal of contributions of the test signals and reception by the receivers 312, to determine perturbations. The apparatus 310 may indicate a determined perturbation to the apparatus 320 and/or the performance evaluation unit 330 and/or the DUT 340. Moreover, the interference cancellation unit 313 may be adapted using the observation antenna signals after the at least partial removal/compensation of the test signals. Thereby, the interference cancellation unit 313 may obtain a channel estimate, e.g. a channel impulse response, to perform the compensation. Further, the signal integrity unit 314 may for example use a correlation to detect whether a perturbation is caused by a change of a room geometry or by an external interferer.

Moreover, the apparatus 320 may comprise a recalibration and correction unit 321 , a testing/calibration signal waveform generation unit 322 and/or a probe array 323. The recalibration and correction unit 321 may use test signals provided by the testing/calibration signal waveform generation unit 322 to obtain channel estimates. The recalibration and correction unit 321 may use the channel estimates (e.g. in the form inverted channel impulse responses) to precondition the test signals before transmission to the DUT 340 via the probe array 323, such that the test signals may be received substantially free of multi-path propagation effects at the DUT 340. In addition to compensating undesired channel characteristics, a pre-distortion may optionally be applied, to thereby emulate a desired channel characteristic. Moreover, the testing/calibration signal waveform generation unit 322 may provide the test signals (or control signals indicating which test signals should be transmitted to the DUT) to the performance evaluation unit 320 and/or the interference cancellation unit 313 and/or the recalibration and correction unit 321. Furthermore, the performance evaluation unit 330 may be used to evaluate a characterization or to label a characterization as compromised/invalid if an undesired interferer was active, which could not be compensated for. For that purpose, the performance evaluation unit is being notified by the apparatus 310 via a measurement integrity notification line 331. The DUT 340 may be provided with an interference estimate via a feed-forward line for post-correction 341. The interference estimate may be used by the DUT 340 to remove unwanted signal contributions from a received signal for characterization (or during characterization) of the DUT 340. Alternatively, the performance evaluation unit 330 may be part of the apparatus 320.

Fig.4a shows a schematic block diagram of a system 400 according to embodiments of the invention in an uplink configuration. The system 400 is similar to the system 300 and comprises the apparatus 310 and an apparatus 420 for characterization of a wireless communication component/system/network. Moreover, the system 400 may comprise the performance evaluation unit 330 and a DUT 340 may be arranged in a test environment, in which the system is located.

Fig. 4b show a bidirectional measurement setup in which the features and functionalities correspond to the features and functionalities describe with reference to Figs. 3 and 4a. Blocks having identical reference numerals comprise similar functionalities. The performance evaluation unit 330' combines the functionalities of the performance evaluation unit 330 according to Fig. 3 and of the performance evaluation unit 330 according to Fig. 4a. Recalibration and correction unit 421 ' is a bidirectional unit and combines the functionalities of the recalibration and correction units 421 and 321 . The probe array 423' is a bidirectional probe array an combines the functionalities of the probe arrays 323 and 423. Thus, the arrangement of Fig. 4b allows for test of both uplink and downlink functionalities, wherein the apparatus 310 is reused in both link directions. The apparatus 310 has the same functionalities and features as described with respect to Fig. 3.

The apparatus 420 is, in comparison to apparatus 320, slightly altered to work in uplink configuration, i.e. test signals are received from the DUT 340 by the apparatus 420. For that end, the apparatus 420 may perform an equalization of muitipath propagation effects in a recalibration an correction unit 421 . For that purpose, the recalibration and correction unit 421 may have initially estimated (inverted) channel impulse responses, which can be used in combination with test signals emitted by the DUT 340 to at least partially compensate an effect of multipath propagation. The compensation may alternatively also be performed at the performance evaluation unit 330. Moreover, the apparatus 420 comprises a testing/calibration signal waveform generation unit 422 which provides the test signals (or control signals indicating which test signals should be transmitted by the DUT) to the DUT 340 and/or the apparatus 310 and/or the recalibration and correction unit 421 and/or the performance evaluation unit 330. Further, the apparatus 420 may comprise a probe array 423 to receive signals from the DUT 340.

Moreover, the apparatus 420 may compensate for an external interferer using an interference estimate, for example, obtained via the feed-forward line for post-correction 341 . Furthermore, the apparatus may be set to re-estimate a channel estimate upon reception of a notice via a channel calibration update line 424.

To conclude, the systems 200, 300 and 400 can observe a measurement of a DUT, such that perturbations caused, e.g. by change of a room geometry of the measurement environment or by an undesired object and/or caused by an interfering source, can be determined. Based on the determination the systems can react appropriately, e.g. use countermeasures like interference cancellation or re-estimation of channel estimates used for characterization of the DUT. Alternatively or additionally, the determination of the perturbation can be used to grade a measurement, e.g. mark it as invalid if strong perturbations occurred, e.g. indicating a need of repeating a measurement. Fig. 5 shows a schematic of a measurement scenario in a first time step according to embodiments of the invention. In the measurement scenario a system 500 is used, corresponding to systems 200 or 300 or 400. The system comprises a probe array (e.g. an antenna array or an antenna movable, e.g., by a robotic arm) 523 used for characterization of a DUT 540 and an auxiliary probe array 51 1 used for an observation of the characterization. The auxiliary probe array 51 1 is used to obtain the observation antenna signals.

The auxiliary antenna array 51 1 comprises, for example, 3 antennas (generally speaking, at least one antenna, or typically more than two antennas such as a distributed or collocated antenna array). The probe array 523 for characterization of the DUT 540 is arranged (or movable), for example, along an arc over the DUT 540. The DUT 540 is placed in a measurement environment 560, which comprises a quiet zone (a zone where environment changes are not supposed to occur) 560a and an outer zone 560b. In the measurement environment first obstacles 562 are present which cause reflections, which may be perceived by antennas of the system 500 or the DUT 540. Therefore, a calibration is first performed to account for the reflections of the first obstacles 562. The first obstacles 562 are, for example, arranged further distanced from the DUT 540 than the probe array 523 and are also typically further distanced from the DUT 540 than the auxiliary antennas 51 1 . Moreover, second obstacles 564 may be present in the measurement environment, which are sufficiently distanced to the system 500 or the DUT 540, such that no significant influence is perceived, due to reflections from the second obstacles 564. In other words, the second obstacles 564 are located further away from the DUT 540 than the first obstacles 562. Fig. 6 shows a schematic of a measurement scenario, based on the scenario from Fig.5, in a second time step according to embodiments of the invention. In Fig. 6 one of the first obstacles 562 has moved compared to Fig. 5, causing a change of room geometry of the measurement environment. Moreover, one of the second obstacles 564 has moved closer to the system 500 and the DUT, such that its reflections are no longer negligible, leading to an additional perceived change of the room geometry. The change of room geometry is captured via the auxiliary array 51 1 (since the change of the room geometry is reflected by a change of signals provided by the antennas of the auxiliary array) and detected, e.g. using power detection and/or a correlation (performed on the basis of the antenna signals of the antennas of the auxiliary array 51 1 , or on the basis of signals originating from the antennas of the auxiliary array 51 1 in which an impact of the transmitted signals used for the characterization of the DUT 540 is (at least partially) cancelled under the assumption of a channel corresponding to a previous room geometry). Further, the change of room geometry can be accounted for by recalibration, e.g. recalibration using unit 321 , 421 and/or 313, or by labeling of the measurement as compromised.

Moreover, an additional external disturbance source 610 may be active which may be detected using the auxiliary array 51 1 , e.g. using power detection and/or a correlation. The interference captured using the auxiliary array 51 1 can be used to obtain an interference estimate, which may be used to compensate for the interference in the characterization. Alternatively, the measurement may be marked as compromised and may for example be repeated. Fig. 7 shows a schematic block diagram of a wireless communication component 700 according to embodiments of the invention. The wireless communication component 700 is configured to obtain an interference signal estimate 701 via a control channel 702, when the wireless communication component 700 is in a characterization mode. Moreover, the wireless communication component may be configured to at least partially compensate an interference signal which is included in a received signal 703 based on the interference signal estimate 701 . The wireless communication component 700 may for example be one of the DUTs 230, 340 or 540. The wireless communication component 700 allows fast and easy characterization using the control channel 702.

Fig. 8 shows a flow chart of a method 800 according to embodiments of the invention. The Method 800 can be used for use in a characterization of a wireless communication component/system/network in a measurement environment. The method 800 comprises determining 8 0 a perturbation of a measurement environment based on one or more observation antenna signals.

Fig. 9 shows a flow chart of a method 900 according to embodiments of the invention. The Method 900 can be used for characterizing a wireless communication component. The method 900 comprises obtaining 910 an interference signal estimate via a control channel, when the wireless communication component is in a characterization mode. Moreover, the method 900 comprises at least partially compensating 920 an interference signal which is included in a received signal based on the interference signal estimate The methods 800 and 900 can be supplemented by any of the features and functionalities described herein, also with respect to the apparatus.

Further aspects and conclusion In the following, some aspects and thoughts according to the present invention are treated.

Anechoic chambers have been used for decades to perform RF measurements. It has been found that considering a non-anechoic environment to perform OTA measurements imposes two major issues that should be addressed: 1 . No Shielding

• The device is vulnerable to interference originating from externa! sources

• The measurement should take place in a controlled environment, however, the device should still be able to observe unpredicted channel changes 2. No Absorption

• Measurement signals travels through a multipath wireless channel

• A pre-calibration phase should be performed in order to determine the correction needed for a particular multipath channel and the same shall be updated with respect to the changes of the wireless channel

The OTA test measurements can be performed in a non-anechoic environment providing that a prior calibration phase has been completed. The pre-calibration phase is then followed by an active OTA measurement phase throughout which the calibration should remain fully valid and, moreover, no other sporadic disturbances should occur within the active measurement phase.

According to embodiments of the present invention, the possibility of conducting such tests in an echoic and (potentially) non-stationary (The stationarity property of the channel can be violated to some certain degree with respect to the channel change from the pre- calibration phase to the active measurement phase) environment is enabled by checking the pre-calibration validity and/or observing the source of disturbances while the measurement is taking place. When the observation is being handled (as in this invention), the correction of any variation or deviation of the observed channel may optionally be performed. Additionally, the disturbances (in-band interference) caused by external sources, which could unpredictably occur any time, may optionally be dealt with.

In contrast to conventional concepts, embodiments of the present invention assures high- fidelity OTA measurements in (non-stationary) multipath environments. In the following OTA measurements in non-anechoic environments are discussed.

The invented system offers unprecedented possibility to perform OTA measurements in non-anechoic and many other uncontrolled environments. The system mechanism is invented to observe significant changes/disturbances - that fall within the frequency range of interest - and that when they occur, the system is notified and then reacts accordingly. The invented system - including the proposed auxiliary hardware and operation procedures - offers one or more of the following features: 1. In-band disturbance detection method caused by the external sources

2. Detection of multipath channel calibration obsolescence (not being up-to-date), due to surrounding environment changes

3. Dynamic (on-the-fly) recalibration procedure for the channel information

4. Feed-forward and post-correction/evaluation capability

The need of performing the measurements in an anechoic chamber [1 ] can be eliminated by the utilization of the invention concept. Additionally, the same concept can be combined to enhance some existing systems such as in an anechoic chamber. For instance, integrating the invented system to a conventional anechoic chamber can offer a "watch dog" feature. In other words, the occurrence of unwanted variation can be observed and reported (if not corrected). This assures a measurement of high fidelity and no violation during such that passes through undetected (unprocessed).

Figure 5 Illustrates the non-anechoic OTA measurement system 500 concept. The auxiliary array manifold 51 1 and zone 560b of potential significant reflection are shown. The zone 560b of potential significant reflection is presumed to remain stationary within the pre-calibration phase. A quiet zone surrounds the DUT and measurement device setup can be imagined assuring that there are no reflections exceeding an upper bound of the reflected signal power, which can still be treated (compensated) by the system. Residing inside the quiet zone 560a should not lay an external obstacle that reflects back significant power (that could desensitize the system receivers).

Figure 5 and Figure 6 illustrate the concept of an/the improved OTA measurement system. The measuring probes and the DUT as part of any ordinary OTA measurement setup are shown in the figures. An example of the auxiliary antenna array manifold, is represented by a 3-antenna collocated (distributed) array 51 1 in the same figures (It should be noted that the number of the antennas is not limited to three and that their location can be anywhere within or outside of the OTA measurement environment.). The auxiliary antenna array 51 1 (In the realization of the system, the antenna array elements are connected to receiving front-ends. Then, the digital output from the front-ends is connected to the Interference cancellation unit.) is proposed to observe and detect the (1 ) unpredicted variation in the multipath environment and/or (2) the source of disturbances. This auxiliary system (e.g. apparatuses 100, 210 or 310) - an augmentation to the ordinary OTA setup - detects channel variation and/or in-band disturbances while the system performs OTA measurements (e.g. simultaneously). In other words, the OTA measurement setup calibrates a current multipath environment, then starts to perform the OTA measurements. Within the OTA measurement phase, all changes and/or disturbances to the channel that fall in the measurement frequency range of interest are detected and recorded by the auxiliary antenna array and its associated equipment. The auxiliary system is continuously fed by the OTA transmit signals, this allows the auxiliary system to distinguish between the actual (physical) multipath changes and different kind of emulated multipath; assuming that the OTA system tries to simulate (or emulate) a multipath channel, e.g. pre-equalizing (or pre-distorting) the signal for test purposes (which may be conducted by the recalibration and correction unit 321 ). In this, way the auxiliary system does not confuse between the deliberate/emulated multipath components and the environment caused ones, enabling by that the auxiliary system to correct for the relevant multipath changes. Figure 6 Illustrates the non-anechoic OTA measurement system 500 concept. The influences caused by: (1 ) in-band disturbance external sources 610, and/or (2) due to environment changes are shown (obstacles 562 and 564 are moved). The gray shaded area 560 represents the virtual anechoic calibrated environment 560. The dotted line arrows depict the movement of the reflection obstacles that have influence on the virtual anechoic calibrated environment 560 (This is to illustrate the effectivity of the invented system in maintaining the virtual anechoic environment).

The system mechanism is engineered to cope with multipath components for the OTA measurements or any kind of measurement that requires a virtual anechoic environment. For this purpose, the system may execute a calibration phase to acquire the multipath channel reverberation and pre-/post-equalize for it, see Figure 5. During this phase, the channel is assumed to be stationary or its stationary property is handled within the estimation techniques. This calibration (estimation and equalization) routine is executed among all components - the ordinary set of OTA-device probes, DUT antennas and the auxiliary set of antennas. This calibration routine allows the on-hand setup to maintain what shall be called a virtual anechoic calibrated environment (see the gray shaded area 560 in Figure 6); it can be imagined as a space surrounding the system in which all the reflection caused by the obstacles inside it are effectively suppressed (pre-/post- equalized), and the expansion of such is dictated by the required power dynamics at the receivers of the OTA equipment. Once the knowledge of all these channels has been acquired, the system starts performing the OTA measurement.

The rest of the paragraph explains the proposed mechanism, in order to maintain a calibrated system state, an idea underlying embodiments of the invention. The auxiliary antenna array manifold 51 1 cancels the ongoing OTA measurement signal at their connected receivers 312, this is possible by taking advantage of the measurement waveform knowledge and the recently acquired channel knowledge during the calibration phase (self-interference cancellation techniques can be used to realize this function [2] [3] [4] [5] [6]). This enables the receivers 312 that are connected to the auxiliary antenna array manifold 51 1 or 311 to pick up any changes in the environment. Technically, having the interference cancelled on the auxiliary manifold 51 1 or 31 1 receivers frees their dynamic ranges and allows them to sense significant changes in the environment based on power increment detection techniques. The system detects any increment in the received signal power, records it and analyzes it in a real-time process, and then reacts accordingly. The channel variation (which may, for example, be estimated or determined based on the signals receive by the receivers) is then used to update the channel information (for example, describing the channel between a transmit antenna and the auxiliary array, and a channel between the transmit antenna and the DUT) that may have been acquired during the pre-calibration phase. These frequent channel updates based on the observed events allow the validity (calibration) of the virtual anechoic environment to be maintained.

In the following components are discussed of a system according to embodiments of the invention which may be incorporated individually or in combination into the apparatus 100 or the system 200, 300, 400 or 500. However, it should be noted that the separation into different blocks or unit may be chosen differently. In other words, some or all functionalities may be combined in a processing block, or distributed to separate apparatuses.

In the following the signal integrity detection unit 314 is further described. During the OTA active measurement phase, this unit constantly listens to reception signal at the auxiliary array manifold 31 1 or 51 1 . This allows the unit to observe the channel (surrounding) changes or 3rd source disturbances. For the sake of observance realization, power detection mechanism is utilized within this unit. The detection of power increment is reported by this unit to the Recalibration and correction unit 321 or 421. These raised flags based on the detection of power increment can be delivered to some other unit - for instance a performance evaluation unit 330, see Figure 3 or 4 - to obtain the knowledge about any disturbance that has disrupted the measurement fidelity. A deliberately created interference or perhaps interference should not be eliminated to mimic realistic cases can be fed to this unit. Hence, this unit 314 offers a feature where these declared (fed) interferences are skipped over untreated to recreate the wanted realistic environment conditions.

In the following the recalibration and correction unit 321 or 421 is further described.

For example, triggered by the Signal integrity unit 314, this unit 321 or 421 may execute a recalibration routine. Additionally, the initial phase of calibration (the precedent phase to the OTA measurement active phase) is done by this unit 321 or 421. The (re)calibration may be achieved by estimation procedure utilizing either predefined pilot sequence or a (causal) knowledge of the ongoing OTA transmission signal.

This unit may have another function, which is pre-/post-equalization; or even both equalization phases based on the implementation requirements. The equalization may be done by utilizing mainly the acquired knowledge from the (re)calibration.

In the following the interference cancellation unit 313 is further described.

This unit 313 is fed by a stream of the ongoing OTA transmission signal (most likely digital samples), e.g. the test signals, in addition to an up-to-date channel knowledge, e.g. channel estimate. The unit utilizes these feeds to cancel the self-interference cancellation (SIC) signal at the auxiliary antenna array manifold [3].

In the following an observation and correction procedure is described according to embodiments of the invention, which may be performed e.g. by system 200, 300, 400 or 500. 1 . During a calibration phase the auxiliary antenna array manifold 31 1 or 51 1 simultaneously receives and estimates the characteristics of the multipath channel within the required range of frequencies

2. Once the knowledge of the required channels among the components has been obtained, the OTA measurement phase may be triggered

3. During the OTA measurement phase, the Interference cancellation unit 313 continuously cancels the received signal at its input; SIC technique is used to achieve this step [2], This signal may go through a corresponding multipath wireless channel, by means of this channel knowledge and the ongoing OTA transmission signal feed, this signal may be canceled. By that, the power dynamic at the auxiliary receivers is freed for better sensitization. This allows the Signal integrity detection unit 314 to sense/detect based on power increasing occurrence.

4. The Signal integrity detection unit 314 may observe/detect the environmental changes by implementing a power detection mechanism. Note that; this may be enabled by means of the SIC within the former step.

5. Once a disturbance to the measurement environment has been observed, the cross-correlation property of the concurrent recorded signal may be examined to determine its category:

a) Uncorrelated may indicate the presence of external source of disturbance b) Correlated may indicate a channel variation occurrence based on surrounding environment change(s)

6. Based on the previous categorization, the system (e.g. 200, 300, 400 or 500) reacts accordingly:

a) The external source signals may be recorded and fed forward for post- correction purpose either to the DUT or the OTA device based on the link direction, see Figure 3 and Figure 4

b) Channel-variation based changes may be used to update/re-§§tim§te the multi-path calibration information, e.g., the reflectors geo-location may be calculated and corrected for the DUT or OTA device antenna(s)/probe(s) location

In the following some application areas are listed.

An OTA Measurement Setup in a Non-Anechoic Environment: The Down and Up Links. Figure 3 and Figure 4 show the embodiments according to the invention in two setups of the OTA measurement, the downlink (DL) and the uplink (UL), respectively. In these two realization concepts:

· Both categories may have an interference cancellation unit 313 that cancels the test sequence at the auxiliary system receivers; based on the estimated channel knowledge and the test signal waveform feed [3,4].

• The Recalibration and correction unit 321 lies in between the Test/calibration

signal waveform generation unit 322/422 and the OTA measurement device probes 323/423 for both realization cases - the DL and UL. This is due to the consideration of a pre-equalizer in the DL case and a post-equalizer for the UL case.

• The Signal integrity detection unit 314 has the assignment of detecting the channel variation or the in-band source of disturbances.

· Once Signal integrity detection unit 314 detects, the unit acts according to the disturbance type. Three feed lines connect the unit to rest of the system blocks.

• In both UL and DL implementations, the Signal integrity detection unit 314 may notify the Performance evaluation unit 330 about the detected test quality (a graded warning system can be considered for such).

· The detected channel variation by Signal integrity detection unit 314 may utilized to update the channel knowledge at the Recalibration and correction unit 321/421 , this is in both UL and DL implementations as on-the-fly recalibration method.

• The feedforward line for post correction 341 , however, differs in the DL

implementation from the UL one. In the DL, it should be delivered to the DUT which is designed to offer a compatible input port and a system feature. In the UL, it can be corrected at the probes output lines, see the difference between Figure 3 and Figure 4.

Figure 3 shows a block diagram showing a system model of the functionality of the invention in the case of an OTA DL measurement. Figure 4 shows a block diagram showing a system model of the functionality of the invention in the case of an OTA UL measurement.

A third realization embodiment, the UL the and DL setups - that are illustrated in Figure 4 and Figure 3 - are combined into one setup where bidirectional link to the DUT may be required to be measured (evaluated). The combined setup is supposed to be an almost straightforward approach where both setup components are combined into one setup. The doubled units such as the Interference cancellation unit 313, and the Signal integrity detection unit 314 do not have to be repeated two times, it can be evolved to a single unit of extended functionality; to handle the jobs from both links/setups in parallel. By that, one auxiliary receiver(s) array manifold is required for this combined setup.

Embodiments describe an observation and correction method for measurement fidelity and signal integrity in non-anechoic OTA measurement environments.

An embodiment according to the invention describes a measurement device, which is capable of coping with wireless channel variations (detecting or/and correcting). In general, embodiments describe devices capable of performing OTA measurement routines in echoic environment - more generally uncontrolled environment.

Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be executed by (or using) a hardware apparatus, like for example, a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important method steps may be executed by such an apparatus. Depending on certain implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be performed using a digital storage medium, for example a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable.

Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed. Generally, embodiments of the present invention can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer. The program code may for example be stored on a machine readable carrier.

Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. The data carrier, the digital storage medium or the recorded medium are typically tangible and/or non- transitionary. A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet.

A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein. A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

A further embodiment according to the invention comprises an apparatus or a system configured to transfer (for example, electronically or optically) a computer program for performing one of the methods described herein to a receiver. The receiver may, for example, be a computer, a mobile device, a memory device or the like. The apparatus or system may, for example, comprise a file server for transferring the computer program to the receiver.

In some embodiments, a programmable logic device (for example a field programmable gate array) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein. Generally, the methods are preferably performed by any hardware apparatus. The apparatus described herein may be implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

The apparatus described herein, or any components of the apparatus described herein, may be implemented at least partially in hardware and/or in software.

The methods described herein may be performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

The methods described herein, or any components of the apparatus described herein, may be performed at least partially by hardware and/or by software.

The above described embodiments are merely illustrative for the principles of the present invention. It is understood that modifications and variations of the arrangements and the details described herein will be apparent to others skilled in the art. It is the intent, therefore, to be limited only by the scope of the impending patent claims and not by the specific details presented by way of description and explanation of the embodiments herein.

Abbreviations:

OTA Over-the-air

UL Uplink

DL Downlink

DUT Device under test

RC Reverberation chamber

MP AC Multi-probe anechoic chamber

CATR Compact antenna test range

SIC Self-interference cancellation

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