WO2019002225A1

WO2019002225A1 - Apparatus and method for use in a characterization of a wireless communication component/system/network and measurement arrangement for characterization of an entity under test usable for compensating changes of a measurement environment before they affect a measurement of the entity under test

Info

Publication number: WO2019002225A1
Application number: PCT/EP2018/066995
Authority: WO
Inventors: Ramez ASKAR; Paul Simon Holt Leather; Kei Sakaguchi; Thomas Haustein; Wilhelm Keusgen
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2017-06-26
Filing date: 2018-06-25
Publication date: 2019-01-03
Also published as: EP3646488A1

Abstract

An apparatus for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment, wherein the apparatus is configured to observe the measurement environment for changes of propagation characteristics, and wherein the apparatus is configured to provide an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change in the measurement environment degrades a characterization result by more than an acceptable impact.

Description

Apparatus and method for use in a characterization of a wireless communication component/system/network and Measurement arrangement for characterization of an entity under test usable for compensating changes of a measurement environment before they affect a measurement of the entity under test

Descri¾ion

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 the Invention Future communication systems, for example those that will be beyond the fourth generations of today (including 5G), will employ highly-integrated radio and antenna systems in which the traditional cable connected interface among the aforementioned parts of the air interface will be removed. With this level of integration, the discrete part of the radio interface chain cannot be examined individually. Therefore, in order to assess the performance of such systems, including the operation of the radio transmitters and receivers, measurements may only be made over the air (OTA).

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. Additionally, many OTA measurement setups will be time consuming (scanning the space etc.), therefore, it is preferred to reduce testing time to its practical minimum. Such time reductions must not however affect the accuracy of the OTA measurement being performed.

Therefore, there exists a desire for an improved concept to perform measurements of wireless communication components/systems/networks, e.g. in arbitrary and/or variable environments.

Summary of thejnverition Embodiments provide an apparatus for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment (wherein a measurement environment can be a measurement scenario, i.e. what an environment which the measurement is confronted with or a deployment environment where measurement is done in a deployed system) . The apparatus is configured to observe the measurement environment for changes of propagation characteristics and to provide an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact.

The described embodiment is based on the idea to observe or/and detect a change of the measurement environment, e.g. by tracking of channel variations, before it affects a measurement. Therefore, a measurement can continue as the changed propagation characteristics can be compensated, e.g. by dynamic channel recalibration, before they are observed in a measurement result, or they lead to degradation of the characterization by more than a predetermined level. Thereby, time-consuming additional recalibration can be avoided, leading to a more efficient characterization of a wireless communication component or of a wireless communication system or of a wireless network. In other words, uninterrupted over-the-air (OTA) measurements can be performed, i.e. a change of the measurement environment which may cause a characterization error which is larger than a tolerable characterization error can be compensated or accounted for.

In embodiments, the apparatus (which may also be termed "auxiliary system") may be configured to be more sensitive to changes of the measurement environment than an equipment (which may also be termed "measurement core system" or "primary receivers") used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network, such that it can detect the change of the measurement environment and update the channel information to allow compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than a (predetermined) acceptable impact. Having a higher sensitivity enables a detection of the change before it is received (or perceived) by other receivers. In embodiments, the apparatus may be configured to be relatively more sensitive to changes of the measurement environment than one or more primary receivers used to receive test signals from the wireless communication component or from the wireless communication system or from the wireless network. Alternatively, the apparatus may be configured to be more sensitive to changes of the measurement environment than one or more primary receivers contained within a wireless communication component to be characterized or than one or more primary receivers contained within the wireless communication system to be characterized or than one or more primary receivers contained within the wireless network to be characterized. The described embodiment can by means of the increased sensitivity allow for an earlier detection of changes before they are received (or perceived or effective to a measurement result) in a measurement chain. Thereby, the apparatus can be used to compensate the changes before they affect the measurement.

In embodiments, the apparatus may be configured to detect a change of the measurement environment which is negligible for the one or more primary receivers, e.g. does not affect a quantized output signal of the one or more primary receivers or is below a reception threshold of the one or more primary receivers. In other words, the change of the measurement environment is detected before the change of the measurement environment results in a non-negligible impact on the one or more primary receivers, e.g. before the change of the measurement environment degrades a characterization result by more than an acceptable impact. The described embodiment allows for detection of changes before they are perceived (or rise higher than sensitivity level) by the one or more primary receivers, thereby allowing for an (at least partial) predictive compensation of a change of signals obtained by the one or more primary receivers.

In embodiments, the apparatus may be configured to predict an update on the channel information and/or to predict the updated channel information. The described embodiment may be useful to provide updates on the channel information and/or an updated channel information, wherein the update on the channel information and/or updated channel information is useful to at least partially compensate propagation effects in a measurement environment (e.g. early enough to avoid a degradation of measurement results). In embodiments, the apparatus may be configured to report changes of the measurement environment to equipment used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network. The described embodiment is beneficial to allow for a measurement equipment to compensate the changes of the measurement environment based on the report.

In embodiments, the apparatus may be configured to provide an update on the channel information and/or the updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization to equipment used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network. The described embodiment is beneficial to allow for a measurement equipment to compensate the changes of the measurement environment based on the provided update on the channel information and/or the updated channel information.

In embodiments, the apparatus may also be configured to characterize the wireless communication component or the wireless communication system or the wireless network in a measurement environment. Further, the apparatus may be configured to use the updated channel information when characterizing the wireless communication component or the wireless communication system or the wireless network in a measurement environment. An apparatus which can observe changes and perform measurements in combination may be smaller and less costly than individual apparatuses.

It should be noted that the terms "entity under test", "device under test", "wireless communication component", "wireless communication system" and "wireless communication network" are used interchangeably herein.

Embodiments provide for a measurement arrangement for a characterization of an entity under test, which may be a wireless communication component or a wireless communication system or a wireless network, in a measurement environment. The measurement arrangement comprises an apparatus according to one of the abovementioned apparatuses for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment. The measurement arrangement further comprises, at least one primary antenna configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test. Moreover, the measurement arrangement comprises at least one observation antenna (which could also be designated as a "surveillance antenna") configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics. The described embodiment provides a flexible measurement arrangement for a wireless communication component or a wireless communication system or a wireless network. Further, the measurement arrangement allows for continuous measurement, even when changes in a measurement environment occur. Moreover, using separate antennas for the observation and for the characterization, allows for a high degree of flexibility, how antennas can be arranged. Accordingly, an appropriate placement of the antennas can help to observe changes of the measurement environment before the change of the measurement environment degrades the result of the measurement by more than an acceptable impact.

Embodiments provide for a measurement arrangement for a characterization of an entity under test, which is a wireless communication component or a wireless communication system or a wireless network, in a measurement environment. The measurement arrangement comprises an apparatus according to one of the abovementioned apparatuses for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment. The measurement arrangement further comprises at least one primary (probe) antenna (wherein the term "probe antenna" refers to an antenna configured for reception, and wherein the term "primary (probe) antenna" or the term "primary antenna" refers to antennas which may be configured for reception or for transmission or for reception and for transmission) configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test. Moreover, the measurement arrangement comprises at least one observation antenna configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics. Further, the at least one observation antenna is configured or arranged to allow for a detection of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact. For example, configured by choosing directivity of the antenna or arranged outside of electromagnetic attenuation barrier or arranged closer to an uncontrolled area in which an uncontrolled movement of objects which change the propagation characteristics can occur, when compared to the one or more primary (probe) antennas or when compared to the component/system/network to be characterized. The at least one observation antenna may for example, be arranged or be configured such that a change of the measurement environment causes a change of one or more signals provided by the one or more observation antennas which is larger than a change of one or more signals provided by one or more antennas of a link between the measurement arrangement and a wireless component/system/network to be characterized.

Embodiments provide for a measurement arrangement for a characterization of an entity under test, which is a wireless communication component or a wireless communication system or a wireless network, in a measurement environment. The measurement arrangement comprises an apparatus according to one of the abovementioned apparatuses for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment. The measurement arrangement further comprises at least one primary (probe) antenna configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test. Moreover, the measurement arrangement comprises at least one observation antenna configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics. Further, the one or more primary (probe) antennas and the one or more observation antennas are arranged or configured such that a response of the one or more observation antennas to a signal reflected or backscattered by an obstacle object is greater than a response of the one or more primary (probe) antennas to the signal reflected or backscattered by an obstacle object. The described embodiment enables a detection of a reflection or a backscattering, which may be based on a changed geometry of the measurement environment, before it affects signals derived from the one or more primary (probe) antennas, by the one or more observation antennas. Thereby, the embodiment may provide a compensation to signals derived from the one or more primary (probe) antennas, such that an effect of a changed reflection or backscattering is at least partially compensated.

Embodiments provide for a measurement arrangement for a characterization of an entity under test, which is a wireless communication component or a wireless communication system or a wireless network, in a measurement environment. The measurement arrangement comprises an apparatus according to one of the abovementioned apparatuses for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment. The measurement arrangement further comprises at least one primary (probe) antenna configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test. Moreover, the measurement arrangement comprises at least one observation antenna configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics. Further, the one or more primary (probe) antennas are configured or arranged such that directional characteristics of the one or more primary (probe) antennas are directed towards the entity under test. Accordingly, an antenna response to a signal backscattered from an obstacle object - e.g. from a direction behind the electromagnetic attenuation barrier - is at least 3 dB smaller than an antenna response to a signal originating the entity under test. Alternatively, in a transmit case, a signal emitted in the direction of an obstacle object - e.g. in a direction behind the electromagnetic attenuation barrier - is at least 3 dB smaller than a signal emitted in the direction of the entity under test. In other words, the described embodiment may perform, for example, a beamforming towards the device under test, to thereby reduce a sensitivity to reflections from obstacle objects in the characterization. It should be noted that this directivity based technique could be used itself without the presence of an electromagnetic attenuation barrier. Of course both techniques (directional antenna and electromagnetic attenuation barrier) can be combined in one setup as well.

In embodiments, the one or more observation antennas may be arranged further away from an entity-under-test region (region where the entity under test is to be placed, wherein the one or more primary (probe) antennas may be movable or arranged along a border of the entity-under-test region) than the one or more primary (probe) antennas. Moreover, the one or more observation antennas may be configured or arranged to have an omnidirectional characteristic and/or the one or more observation antennas may be configured or arranged to have a directional characteristic directed towards a region in which a presence of an obstacle object is expected, e.g. directed away from the entity under test, and/or the observation antennas may form an antenna array which provides a stronger signal (lower noise floor) than the one or more primary (probe) antennas, e.g. to provide a stronger signal than the one or more primary (probe) antennas. Alternatively or optionally, the one or more observation antenna array comprises a higher element count than the one or more primary (probe) antennas The described embodiment allows for flexible configuration of the observation antennas, wherein the arrangement of the one or more observation antennas to the contributes to the increased sensitivity of the apparatus with respect to the measurement environment. In embodiments, a combination of an observation antenna array gain and an electromagnetic barrier is also possible. In embodiments, the measurement arrangement may comprise an electromagnetic attenuation barrier. Further, the at least one primary (probe) antenna may be arranged on a first side of the electromagnetic attenuation barrier and the at least one observation antenna may be arranged on a second side of the electromagnetic attenuation barrier, such that the electromagnetic attenuation barrier is arranged between the one or more primary (probe) antennas and the one or more observation antennas. Thus, reflections by the one or more obstacle objects are typically received with larger signal strength by the observation antennas compared to the primary (probe) antennas. Accordingly, an early detection of changes of the measurement environment is possible using the observation antenna signals.

In embodiments, the first side of the electromagnetic attenuation barrier may be directed towards a region for a placement of an entity under test and in which a movement of scattering objects can be prevented. Further, the second side of the electromagnetic attenuation barrier may be directed towards a region in which a movement of scattering objects is possible. Thereby, the electromagnetic attenuation barrier allows for easy separation of the entity under test from moving scattering objects, such that signals reflected therefrom are attenuated in the characterization taking place on the first side. In embodiments the electromagnetic attenuation barrier may be configured to provide for a transmission attenuation between 1 dB and 100 dB for an electromagnetic wave in an operation frequency range of the measurement arrangement.

In embodiments the measurement arrangement may be configured such that the one or more primary (probe) antennas are configured to transmit one or more signals to be received by the entity under test. Further, the measurement arrangement may be configured such that the one or more observation antennas, e.g. an observation array or an observation antenna manifold, are configured to receive one or more signals transmitted by the one or more primary (probe) antennas and, optionally, forwarded through the electromagnetic attenuation barrier. Moreover, the measurement arrangement may be configured such that the one or more observation antennas additionally receive one or more signals transmitted by the one or more primary (probe) antennas and, optionally, forwarded through the electromagnetic attenuation barrier, and backscattered or reflected or refracted or diffracted by an obstacle object in the presence of an obstacle object. Furthermore, the measurement arrangement may be configured to estimate or predict a changed channel characteristic, or a change of a channel characteristic, e.g. of a channel between the one or more primary (probe) antennas and the entity under test, and/or, e.g. caused by a change of a position of the obstacle object, on the basis of one or more signals from the one or more observation antennas. Moreover, the arrangement may be configured to determine a pre-correction, which is applied to one or more signals transmitted to the entity under test, and which pre-correction serves to at least partially compensate an impact of multipath propagation when transmitting a signal from the one or more primary (probe) antennas to the entity under test, on the basis of the estimation of the changed channel characteristic or on the basis of the estimation of the change of the channel characteristic. The described embodiment allows for characterization of wireless communication components/systems/networks in adverse environments, e.g. in a downlink scenario, i.e. transmission from the measurement arrangement to the entity under test, wherein the compensation of the impact of the changed multipath propagation is so fast that an impact on the measurement stays within an acceptable range. In embodiments, the measurement arrangement may be configured such that the one or more primary (probe) antennas are configured to receive one or more signals transmitted by the entity under test. Further, the measurement arrangement may be configured such that the one or more observation antennas are configured to receive one or more signals transmitted by the entity under test. Moreover, the measurement arrangement may be configured such that the one or more observation antennas additionally receive one or more signals transmitted by the entity under test and, optionally, forwarded through the electromagnetic attenuation barrier, and backscattered or reflected or refracted or diffracted by an obstacle object in the presence of an obstacle object. Further, the measurement arrangement may be configured to estimate or predict a changed channel characteristic, or a change of a channel characteristic, e.g. of a channel between the one or more primary (probe) antennas and the entity under test and/or e.g. caused by a change of a position of the obstacle object, on the basis of one or more signals from the one or more observation antennas. Moreover, the measurement arrangement may be configured to determine a post-correction, which is applied to one or more signals transmitted by the entity under test und received by the one or more primary (probe) antennas, and which post-correction serves to at least partially compensate an impact of multipath propagation when transmitting a signal from entity under test to the one or more primary (probe) antennas, on the basis of the estimation of the changed channel characteristic or on the basis of the estimation of the change of the channel characteristic. The described embodiment allows for characterization of wireless communication components/systems/networks in adverse environments, e.g. in an uplink scenario, i.e. transmission from the entity under test to the measurement arrangement, wherein the compensation of the impact of the changed multipath propagation is so fast that there is no need to buffer (delay) or pause (Interrupt) the measurement. In embodiments, the arrangement may be configured to predict an impact of changes of the measurement environment onto signals to be transmitted by the one or more primary (probe) antennas, e.g. in order to obtain desired signals at the location of the entity under test, or onto signals received by the primary (probe) antennas, e.g. an impact onto the "primary receivers", on the basis of the signals received via the observation antennas. For example, the measurement arrangement concludes from changes of the signals received by the observation antennas onto changes of the signals received by the primary (probe) antennas. Further, the measurement arrangement may be configured to provide an update on the channel information and/or the updated channel information on the basis of the prediction. The described embodiment can beneficially provide, based on a prediction, an update on the channel information and/or the updated channel information, wherein signals received by the observation antennas may be sufficient to predict changes of the channel between the entity under test and the primary (probe) antennas. Thus, it may not be necessary to use signals from the primary (probe) antennas for the updating of channel estimates.

In embodiments, the measurement arrangement may be configured to predict a change of geometry and/or to predict an effect of a change of geometry, for example, a change of a position of an obstacle object, which affects multipath propagation characteristics in the measurement environment, on the basis of signals received via the observation antennas, and to provide an update on the channel information and/or the updated channel information on the basis of the prediction. The described embodiment can predict a change of geometry and thereupon deliver an updated channel information.

In embodiments, the measurement arrangement may be configured to perform a calibration before starting a characterization of an entity under test, in order to determine an initial channel information describing a channel among the one or more primary (probe) antennas, the entity under test and the one or more observation antennas, and to use the initial channel information in order to compensate for undesired multipath characteristics of the channel between the one or more primary (probe) antennas and the entity under test. Further, the measurement arrangement may be configured to provide the updated channel information on the basis of signals received by the one or more observation antennas during a characterization of the entity under test, in order to allow for an uninterrupted characterization of the entity under test even in case of a change of multipath characteristics of the measurement environment which occurs during the characterization of the entity under test.

In embodiments, the measurement arrangement may be configured to at least partially cancel a signal component caused by the transmission of one or more signals from the one or more primary (probe) antennas or caused by the transmission of one or more signals from the entity under test from signals received by one or more observation antennas using a knowledge of a previously determined channel information describing a previously determined state of a channel among the one or more primary (probe) antennas and the one or more observation antennas, or between the entity under test and the one or more observation antennas, in order to obtain preprocessed observation antenna signals, such that a sensitivity of receivers for signal components caused by a change of multipath characteristics of the measurement environment is increased, e.g. by using an interference cancellation unit.

In embodiments, the measurement arrangement may be configured to provide the updated channel information on the basis of the preprocessed observation antenna signals, e.g. by use of a channel predictive estimation unit.

Embodiments provide for a method for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment. The method comprises observing the measurement environment for changes of propagation characteristics and providing an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization, e.g. using a dynamic channel recalibration, in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable, e.g. predetermined, impact. Thereby, uninterrupted OTA measurements can be performed. Moreover, before the change of the measurement environment causes a characterization error which is larger than a tolerable characterization error, a compensation can be performed.

The described method can be supplemented by any of the features or functionalities described herein with respect to apparatuses, either individually or in combination. A further preferred embodiment of the invention is a computer program with a program code for performing the method 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 measurement arrangement according to embodiments of the invention;

Fig. 3 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in a downlink configuration;

Fig. 4 shows a graphical representation of signals received at the device under test and at the auxiliary array;

Fig. 5 shows a graphical representation of signals received at the device under test and at the auxiliary array after processing according to embodiments of the invention;

Fig. 6 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in an uplink configuration;

Fig. 7 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in an uplink configuration;

Fig. 8 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in an uplink configuration; Fig. 9 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in a downlink configuration;

Fig. 10 shows a schematic block diagram of a measurement arrangement according to embodiments of the invention in a combined uplink and downlink configuration;

Fig. 1 1 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 or of a wireless communication system or of a wireless network in a measurement environment is configured to observe the measurement environment for changes of propagation characteristics, e.g. using observer 1 10. Further, the apparatus 100 is configured to provide an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact, e.g. using provider 120. Additionally or optionally, the apparatus 100 may comprise a low noise/high sensitivity receiver 130. The apparatus 100 may receive a signal 101 of an observation antenna through the receiver 130. Based on the received signal 101 an observation may be performed, by observer 1 10, to observe the measurement environment for changes. Based on an observed change, the change may be reported by the apparatus 100 to a further equipment or apparatus via the optional line 103. Alternatively or additionally, the apparatus 100 may report the change via line 102 to the provider 120. The provider 120 is configured to estimate an updated channel information and optionally provide it to a further apparatus or equipment via line 104.

More detailed features and functionalities of apparatus 100 will be described in in context of the measurement arrangements 200, 300, 600, 700, 800, 900 and 1000 in Figs. 2,3,6,7,8,9 and 10. 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 measurement arrangement 200 according to embodiments of the invention. The measurement arrangement 200 is usable for a characterization of an entity under test 230, which is a wireless communication component or a wireless communication system or a wireless network, in a measurement environment. The measurement arrangement 200 comprises an apparatus 210 which may correspond to apparatus 100. The measurement arrangement 200 further comprises at least one primary (probe) antenna 220 configured to transmit a test signal to an entity under test 230, and/or configured to receive a test signal from an entity under test 230. Further, the measurement arrangement 200 comprises at least one observation antenna 240 configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics.

The at least one observation antenna 240 is connected to the apparatus 210, to provide an observation signal. Based on the observation signal, the apparatus 210 can detect or predict changes in the measurement environment such that they can be accounted for in the measurement of the entity under test 240. In the following, ways of accounting for changes of the measurement environment will be described in more detail, with respect to measurement arrangements 300, 600, 700, 800, 900 and 1000 in Figs. 3,6,7,8,9 and 10.

The measurement arrangement 200 can be supplemented by any of the features or functionalities described below, either individually or in combination.

Fig. 3 shows a schematic block diagram of a measurement arrangement 300 according to embodiments of the invention in a downlink configuration, i.e. test signals are transmitted by the arrangement 300 and received by a device under test (DUT) 330. The measurement arrangement 300 comprises an apparatus 320 for use in a characterization of a wireless communication component/system/network, an apparatus for characterizing a wireless communication component/system/network 330 (entity under test). Moreover, the arrangement 300 comprises a recalibration and correction unit 305, which may also be used for pre-correction, a testing/calibration signal waveform generation unit 315, a probe array 320, an electromagnetic attenuation barrier 325, an auxiliary array 335 (e.g. comprising observation antennas) and a device under test 330. Further, in the measurement environment an obstacle 340a-c is moving. The apparatus 310 comprises an auxiliary array 335, an interference cancellation unit 31 1 , a signal integrity detection unit 312 and a channel predictive estimation unit 313. The device under test 330 is placed under an arc-shaped probe array 320, which comprises the primary (probe) antennas. Further distanced from the device under test 330, beyond the probe array 320, the electromagnetic attenuation barrier 325 is located. The electromagnetic attenuation barrier 325 is placed between the obstacle 340a-c and the device under test 330. The obstacle is shown for a first time frame as 340a, for a second time frame as 340b and for a third time frame as 340c, wherein the second time frame follows the first time frame and the third time frame follows the second time frame. Further, reflected signal propagation paths are illustrated showing a test signal being emitted from a probe of the probe array 320, reflected from the obstacle. In each of the time frames 340a-c, a signal path is shown towards the auxiliary array 335 and the device under test 330, via the obstacle 340a-c. A path 341 a for the first time frame, a path 341 b for the second time frame and a path 341 c for the third time frame from the probe to the auxiliary array 335 is shown in dashed lines. Moreover, solid lines 342a-c are illustrating reflections from the obstacle in the first, second and third time frame to the device under test 330, traversing the electromagnetic attenuation barrier 325 twice on the way from the probe array 320 to the device under test 330.

The auxiliary array 335 receives the test signals emitted via the probe array 320 and reflected from the obstacle in the individual time frames. In the first time frame the apparatus 310 may be in a calibrated state, i.e. signals emitted from the probe array 320 may be suppressed or cancelled (at least partially) using interference cancellation unit 31 1 and test signals provided by the testing/calibration signal waveform generation unit 315. Based on the processed signal, i.e. after interference cancellation, the signal integrity detection unit 312 can detect changes of a channel in the measurement environment. When a change has been detected it can be used by the channel prediction estimation unit 313 to provide an updated channel information, e.g. based on a previously estimated channel information. The recalibration an correction unit 305 can, based on the updated channel information, provide signals to the probe array 320, such that they are perceived as free of multipath propagation at the device under test 330 (or such that a desired channel characteristic is emulated irrespective of the movement of the obstacle). In consequence, due to the interference cancellation unit 31 1 , which aims at cancelling received signals based on the test signals and based on a channel condition at a time of an initial calibration, a reflection received via signal path 341 a may be received strongly attenuated at the apparatus 310. In the second time frame the obstacle has moved and its location is now 340b, which may not be covered within the initial calibration of the interference cancellation unit 31 1 . Therefore, a signal may be received by the apparatus 310 which has a higher level than in the first time frame. The movement also causes a change of the received signal of the device under test 330, which is, however, smaller than the one observed in the apparatus 310, due to the electromagnetic attenuation barrier 325. As the reflected signal needs to cross the electromagnetic attenuation barrier 325 only once on the way to the auxiliary array 335, compared to twice on the way to the device under test 330, it is observed stronger at the apparatus 310. The apparatus 310 can, therefore, use a knowledge of a changed channel, based on the movement of the obstacle, to compensate, for example, quasi-instantaneously or in a third time frame, an potential influence or impact of the movement onto the reflected signal received by the device under test 330.

The arrangement 300 may perform a preprocessing to the test signals before they are emitted from the probe array 320. The preprocessing can be used to achieve a compensation of multipath effects at the DUT 330, thereby, measurements can be performed in non-anechoic environments, saving the need for an anechoic environment.

Similarly, in an uplink scenario, the arrangement 300 can equalize signals received from the DUT 330 such that multipath propagation effects are at least partially compensated.

However, both preprocessing and equalization benefit from up-to-date channel information, which can be dynamically provided by apparatus 310, such that pausing of measurements can be avoided.

Generally speaking, Figure 3 illustrates an OTA measurement device placed in a non- anechoic/no-stationary environment. The OTA measurement device measures the downlink (DL). An example of an one-moving-obstacle environment is shown; the obstacle movement is flashed in three consecutive positions (1 ~>2->3). The system blocks are also shown in the figure. The surface of the measurement equipment may be covered with absorptive (non-reflective) material to prevent reflection on it. The dashed lines 341 a-c represent the signal reflected from obstacle to the auxiliary antenna array manifold 335, while the solid lines 342a-c represent the reflected back signal to the DUT. The dash- dotted line depicts the line-of-sight (LoS) multipath component between the probe 320 and the auxiliary antenna 335. The double dotted and dashed line represents the LoS between the probes 320 and the DUT 330.

Fig. 4 and Fig. 5 show graphical representations 400A, 400B, 450A and 450B of signals received at the device under test 330 and at the auxiliary array 335. The graphs 400A, 400B, 450A and 450B correspond to the scenario depicted in Fig. 3.

In graph 400A signals received at the device under test are shown for the first time frame t_lt the second time frame t₂ and the third time frame t₃, corresponding to the time frames of obstacle movement 341 a-c. A line-of-sight (LoS) component is observed for the first time frame 40 a, for the second time frame 40 b and for the third time frame 401 c. Moreover, a reflection component is shown for the first time frame 402a, the second time frame 402b and the third time frame 402c. In the first time frame the reflection component 402a is pre calibrated (e.g. at least partially cancelled by the interference cancellation unit 31 1 on the basis of a previously available channel information) and lower than a receiver sensitivity level. In the second time frame the reflection component 402b is equivalent to the receiver sensitivity level and, therefore, still not impacting a measurement. In the third time frame the reflection component 402c is above the receiver sensitivity and, therefore, impacts a measurement in the absence of processing discussed herein.

In Fig. 5 a graph 400B is shown, similar to graph 400A, which represents signals after processing by embodiments of the invention, wherein the reflection component 402d, corresponding to 402c, is compensated, such that it does not impact the measurement. In graph 450A signals received at the auxiliary array are shown for the first time frame t_{l t} the second time frame t₂ and the third time frame t₃, corresponding to the time frames of obstacle movement 341 a-c. LoS components 451 a-c and reflection components 452a-c are shown, corresponding to the first time frame, the second time frame and the third time frame. The auxiliary receiver receives the reflection component 451 b in the second time frame higher (i.e. detectable) compared to reflection component 402b in the DUT, such that the apparatus can use the reception to predict a rising reflection component in the DUT receiver. In other words, a rising reflection component can be detected by the apparatus 310 before it is perceived by the DUT 300 being above a noise floor or receiver sensitivity. Therefore, based on the reception of the rising reflection components 452b, a compensation of the reflection can be performed by an adaptation of signals (e.g. using recalibration an correction unit 305) transmitted to the DUT. Moreover, a re-estimation of channel information is triggered by embodiments, as can be seen in graph 450B in Fig. 5, for example, in response to a detection of a rising reflection by the apparatus 310. Thereby, the reflection component in the third time step 452d in graph 450B may stay constant, i.e. has a comparable level to reflection component 452b in the second time step in graph 450A or graph 450B. Moreover, by adapting the signals transmitted to the DUT based on the knowledge of the changed reflection by the obstacle (which adaptation is initiated or performed by the apparatus 310), it can be achieved that the reflection component 402d received by the DUT in the third time frame remains small enough so as not to impact a measurement result (at least not by more than an acceptable impact). Thus, the measurement result can be considered as "still calibrated" even in the third time frame when using the concept according to the present invention.

Similarly, the compensation may be performed in an uplink (UL) scenario, in a receiver path of the probe array 320.

Generally speaking, in Figure 4 the timeline of changes of the channel impulse responses (CIRs) due to the movement of the obstacle in the surrounding environment are compared between the auxiliary and DUT receivers, where no predictive recalibration method is used.

Generally speaking, in Figure 5 the timeline of changes of the CIRs changes due to the movement of the obstacle in the surrounding environment are compared between the auxiliary and DUT receivers. The predictive re-estimation and recalibration method, which is underlying embodiments of the invention, is triggered at time instant t₂ to maintain the calibrated state before it affects the DUT receivers. The first CIR figure at the DUT receiver shows how the calibrated state of the channel remains valid as the auxiliary predictive recalibration method ("re-estimation", update of channel information) reacts (e.g. triggered by the detection of the increased reflection component by the auxiliary receiver in the second time frame).

Fig. 6 shows a schematic block diagram of a measurement arrangement 600 according to embodiments of the invention in an uplink configuration, i.e. test signals are transmitted by the device under test 330 and received by the arrangement 600. The arrangement 600 comprises the same features and functionalities as the arrangement 300. Moreover, the arrangement 600 comprises probes in the probe array 320 which are directional, i.e. receive signals impinging from a certain direction with a higher power than from other direction. The probes of the probe array 320 direct beams 321 , 322, 323, 324 and 325 at the DUT 330 such that signals or reflections originating from other directions are comparably attenuated to signals impinging from the DUT 330. Thereby, the auxiliary array 335 has an increased sensitivity to the reflections backscattered from the obstacle 340a-c compared to the probes of the probe array 320. In consequence, signals received via the auxiliary array 335 can be used to predict signals having an impact on the measurement.

Alternatively, in Figure 6 The probes of the OTA measurement device are beamforming towards the DUT to pick up less (attenuated) multipath channel components.

Fig. 7 shows a schematic block diagram of a measurement arrangement 700 according to embodiments of the invention in an uplink configuration, i.e. test signals are transmitted by the device under test 330 and received by the arrangement 700. The measurement arrangement 700 is similar to the measurement arrangement 600, without usage of the directional probes. Moreover, Fig.7 shows predictive channel re-estimation in UL case. The dashed lines 341 a-c represent the signal reflected from obstacle 340a-c to the auxiliary antenna array manifold 335, while the solid lines 642a-c represent the reflected back signal to the OTA measurement device probes 320. The dash-dotted line depicts the LoS multipath component between the DUT 330 and the auxiliary antenna 335. The double dotted and dashed line represents the LoS between the DUT 330 and the probes 320.

Fig. 8 shows a schematic block diagram of a measurement arrangement 800 according to embodiments of the invention in an uplink configuration. The measurement arrangement can be understood as an alternative illustration of the arrangement 700. Further, same reference signs compared to arrangement 300, 600 or 700 indicate similar or same functionality. Fig. 8 shows further, a block diagram showing a system model of the functionality of the invention in the case of an OTA UL measurement.

Fig. 9 shows a schematic block diagram of a measurement arrangement 900 according to embodiments of the invention in a downlink configuration. The measurement arrangement can be understood as an alternative illustration of the arrangement 300. Further, same reference signs compared to arrangement 300, 600 or 700 indicate similar or same functionality. Fig. 9 shows further, a block diagram showing a system model of the functionality of the invention in the case of an OTA DL measurement. Fig. 10 shows a schematic block diagram of a measurement arrangement 1000 according to embodiments of the invention in a combined uplink and downlink configuration. The measurement arrangement can be understood as an alternative illustration of the arrangement 300 and 700. Further, same reference signs compared to arrangement 300, 600 or 700 indicate similar or same functionality. Fig. 10 shows further, a block diagram showing a system model of the functionality of the invention in the case of a combined UL and DL OTA measurement. To conclude, embodiments of the invention allow for a fast recalibration based on a predicted rise of reflection components. Moreover, by having separate auxiliary or observation antennas a change can be detected before it impacts a measurement. Based on the detection appropriate countermeasures, e.g. re-estimation of channel information and/or compensation of the reflection components, can be provided.

Fig. 1 1 shows a flow chart of a method 1 100 according to embodiments of the invention. The method 1 100 comprises observing 1 1 10 the measurement environment for changes of propagation characteristics. Further, the method 1100 comprises providing 1120 an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact.

The method 1 100 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.

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. Anechoic chambers have been used for many decades to perform antenna radiation pattern measurements.

It has been recognized that considering a non-anechoic environment to perform OTA measurements imposes three major issues that should be addressed:

1 . No Shielding

^• The device is vulnerable to interference originating from external sources

^• The device can create interference that affects external and vulnerable components/systems/equipment

2. No Absorption

• Measurement signals travel 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 [7, 8, 9]

3. Un predicted Channel Variation

^• Channel changes - due to variations in the surrounding - occur without warning. Maintaining a valid state of calibration for such multipath channels may thus be considered as an anti-causal system problem

· The recalibration of the multipath channel may, in conventional concepts, result in an interruption of the OTA measurement (time is needed to restore the calibrated channel state);

^• The recalibration process might also lead to system complications due to an OTA measurement being corrupted as the result of recalibration (the channel calibrated state is violated)

It has also been recognized that the OTA test measurements may be performed in a non- anechoic environment preferably after the completion of a prior calibration phase [7, 8, 9]. The pre-calibration phase may then be followed by an active OTA measurement phase throughout which the calibration should remain fully valid.

It has also been found that reliability may be improved by checking the validity of the calibration from time to time. However, the possibility of conducting such tests in a non-anechoic and (potentially) non- stationary environment may be obstructed by the necessity of checking the pre-calibration validity while the measurement is taking place. Even though the measurement process may be under observation, an interruption and delay in the overall measurement process results from the need for recalibration. For example, when performing the observation during an over-the-air (OTA) measurement phase, the interference cancellation unit continuously cancels the received signals at its input. Self-interference cancellation (SIC) may be used to achieve this step [2]. This signal goes through a corresponding multipath wireless channel and, by means of this channel knowledge, the ongoing OTA transmission signal feed should be cancelled so that the dynamic range of the auxiliary receivers is improved for better sensitivity. This allows the signal integrity detection unit 312 to sense/detect based on power increasing occurrence. Embodiments of this Invention thus propose a solution to the problem of tracking channel changes in a non-stationary (multipath) environment to enable an appropriate system recalibration in order to allow eventually an uninterrupted OTA measurement. In contrast to the inventive solution proposal, a non-prediction based method has the following disadvantages:

1 . Interrupted Measurement

• Executing a recalibration routine increases the effective time of measurements and affects continuity

^• In relatively rapid-changing environments, there is a high risk that intermediate recalibration may not provide an accurate and timely set of calibration data to the measurement system

2. Measurement System Complexity

^• In non-prediction based methods, the system most likely must consider a feed-forward correction technique to cope with already-preformed or completed (inaccurate) measurements, during which the system was not in a fully calibrated state. This is due to the relatively slow reaction - detection, estimation and recalibration - of the system to the channel changes; as it does not rely on a prediction basis. 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 DUT, probes and the environment in which they reside, are arranged in such a way that the effects of multipath 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. In contrast, the present invention assures uninterrupted high-fidelity OTA measurements in (non-stationary) multipath environments.

Embodiments of the invented method will offer an the possibility to perform uninterrupted OTA measurements in non-anechoic and many other uncontrolled environments.

A general principle of operation underlying embodiments is to provide a prediction method that allows the system to recalibrate due to changes in the surroundings of the measurement environment before they affect and hence distort the current measurement procedure. An idea underlying embodiments is that an auxiliary measurement system (for example, comprising the observation antennas 240, 335 and the apparatus 100, 310) is continuously observing the environment and hence all (or only some, which may have an impact on the measurement) environmental changes and reports the latter to the measurement system before such changes influence the OTA measurement receivers of the DUT and/or the device probes (collectively, the primary receivers). This may require the auxiliary system to be more sensitive to those changes and to predict their next effect in time reference to the primary receivers.

As a possibility, a delayed reception of the signals, before they are scattered or reflected or refracted or diffracted from surrounding obstacles and arrive at the primary receivers, provides an adequate solution.

Instead of trying to gain a time lag that favors the auxiliary system, in other embodiments (as explained for example taking reference to Figures 1 to 10) the auxiliary system (for example, comprising the observation antennas 240, 335 and the apparatus 100, 310) could be engineered to be more sensitive than the primary receivers (for example, receivers of the entity under test or receivers coupled to the primary (probe) antennas). The auxiliary system is thus enabled to sense and capture minor changes that have concurrently a negligible effect on the primary receivers. Such changes, which may increase over time, have a non-negligible impact on the primary receivers, unless the auxiliary receiver starts to compensate when their effect is still small. This can be thought of as a countermeasure which treats the minor alterations before their manifestation. It is reasonable to assume that channel perturbations are the result of physical changes in the environment (for example a movement of an obstacle) and that such changes therefore occur at much slower speeds than the speed of light (Assuming that the recalibration system reacts faster than the channel changes) ; e.g., caused by obstacle movement. In summary, the gradual nature of the mu!tipath channel reflection changes allows the oversensitive (highly-sensitive, enhanced sensitivity or high sensitivity) auxiliary system to capture them. Such changes are relatively minor and can be processed immediately by the primary receivers' recalibration systems. Eventually, continuous prediction methods ensure that multipath channel variations are dynamically recalibrated and thus have no noticeable effect on the primary receivers.

In the following, a predictive channel re-estimation for OTA measurement systems is discussed, underlying embodiments of the invention. Figure 3 shows an OTA measurement setup 300 measuring of the downlink (DL). The application of the invention is not limited to the DL. The DL is used as a use case to explain an idea of the invention. The reader is referred to the uplink (UL) embodiments to see the UL use case. The OTA measurement device 300 is functioning as a transmitter whereas the DUT 330 is the receiver. A one-moving-obstacle environment is chosen to illustrate the principle of operation. The obstacle (reflector) is depicted at three consecutive positions 340a-c corresponding to three time instances t_{l t} t₂ and t₃ , respectively. The auxiliary array 335 receives the reflected signal from the environment obstacles and uses it to re-estimate the channel impulse response (CIR), e.g. in the channel predictive unit 313. The updated CIR will be used to recalibrate the channel information and retain the channel calibrated state; assuming that the system starts from a multipath-channel-calibrated state (the channel where the obstacle at position 1 340a is pre-calibrated).

In the following, it is discussed how the system achieves a prediction of unexpected environmental changes. As shown in Figure 3, the signal transmitted by the the probes of the OTA measurement device is received by both the DUT receiver(s) and the auxiliary antenna array 335. However, the mu!tipath or reflected component(s) (excluding the LoS component) are attenuated by a factor of 2a before reaching the DUT 330 receivers. By comparison, the same components are attenuated by a factor of a before impinging on the auxiliary array 335 (a difference in the received attenuation factor due to the pathloss variation, between the auxiliary and the DUT receivers, is neglected; assuming that both receiving systems are located close to each other). The attenuation factor of the material is represented by a as illustrated by the red barrier 325 in Figure 3. This makes the auxiliary array receiver relatively more sensitive to the multipath channel variation.

Figure 4 and Figure 5 show the CIR of the multipath wireless channel without and with utilization of the proposed prediction method, respectively. These figures interpret what is illustrated in Figure 3 - i.e. the one-moving-obstacle environment - in terms of the channel impulse response. The CIR at the DUT in Figure 4 shows how the moving obstacle violates the multipath calibrated state as the moving obstacle approaches position 3. In contrary, in Figure 5 the success of the prediction method in maintaining the calibrated state is illustrated as the re-estimation and the update (correction) on the channel state information triggered at time instant t₂. By that the DUT was not affected by the channel changes as the auxiliary predicts and updates the channel information. The prediction allows the pre-equalization method to react fast enough as no post-correction would be required anymore.

In the following, further techniques to compete with the system's anti-causality are discussed

The attenuation barrier 325 is not the only technique that could be utilized to compete with the anti-causality of the system. Other techniques can be used to provide the relative over-sensitivity needed for the auxiliary receiving. The following techniques, in addition to the conventional attenuation barrier based one, are proposed to be used either separately or in a combination of many:

1. The auxiliary array receiving system is more sensitive than the rest. An over- dimensioned array (an array having a high element count) is used to reduce the noise level of the receivers in accordance to the array gain. 2. The probes' receiving beam pattern are highly directed towards the DUT, i.e. the reception multipath reflections are attenuated, see Figure 6 beams 321 , 322, 323, 324 and 325. This makes the auxiliary system more sensitive to the multipath reflections than the OTA measurement device probes.

In the following, features of the predictive channel re-estimation method are discussed.

Embodiments of the invented prediction method - rely on an auxiliary receiver system and operation procedure - which offers the following features: . Continuous re-estimation (updating) of the multipath wireless channel

2. Dynamic channel recalibration, i.e. non-obsolete (outdated) channel information

3. Predictive channel re-estimation and tracking for the channel variations

4. Uninterrupted OTA measurements in non-anechoic environments

5. Reduction in measurement system complexity

6. Speed improvement of the measurement process

In the following, application areas are discussed.

In addition to the DL application of the predictive channel re-estimation, the same concept can be applied to the UL case. Figure 7 shows similar setup to the DL one where the DUT plays the transmitter and the OTA measurement device probes 320 are the receivers.

In the following a prediction enhanced OTA measurement setup in a non-anechoic environment in downlink and uplink is discussed.

Figure 8 and Figure 9 show the predictive method involvement in realization embodiments of the two setups of the OTA measurement, the DL and the UL, respectively. A combination of both UL and DL are shown in Figure 10; where the recalibration and correction unit is handling both directions by means of pre- and post-equalization. Embodiments of the invention have the capability of coping with wireless channel variations (detecting or/and correction). In general, embodiments of the invention are capable of performing the OTA measurement routines in a non-anechoic environment - more generally uncontrolled environment.

Further embodiments describe a prediction-based method for performing uninterrupted OTA measurements in non-stationary multipath environments.

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

MPAC Multi-probe anechoic chamber

CATR Compact antenna test range

SIC Self-interference cancellation

SI Self-interference

LoS Line-of-sight

CIR Channel impulse response References:

[1 ] 3rd Generation Partnership Project (3GPP), "TR 37.976, 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)," 3GPP, 2016.

[2] R. Askar, B. Schubert und W. Keusgen, "TRANSCEIVER AND METHOD FOR REDUCING A SELF-INTERFERENCE OF A TRANSCEIVER". PCT Patent WO/2017/008851 , 19 1 2017.

[3] R. Askar, T. Kaiser, B. Schubert, T. Haustein und W. Keusgen, "Active self- interference cancellation mechanism for full-duplex wireless transceivers," in Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM), 2014 9th International Conference on, 2014.

[4] R. Askar, B. Schubert, W. Keusgen und T. Haustein, "Agile Full-Duplex Transceiver:

The Concept and Self-Interference Channel Characteristics," in European Wireless 2016; 22th European Wireless Conference, 2016.

[5] R. Askar, N. Zarifeh, B. Schubert, W. Keusgen und T. Kaiser, "l/Q imbalance calibration for higher self-interference cancellation levels in Full-Duplex wireless transceivers," in 5G for Ubiquitous Connectivity (5GU), 2014 1st International Conference on, 2014.

[6] R. Askar, B. Schubert, W. Keusgen und T. Haustein, "Full-Duplex Wireless Transceiver in Presence of l/Q Mismatches: Experimentation and Estimation Algorithm," in IEEE GC 2015 Workshop on Emerging Technologies for 5G Wireless Cellular Networks - 4th International (GC'15 - Workshop - ET5G), 2015.

[7] EP17173796

[8] P. S. H. Leather and J. D. Parsons, "Antenna measurement systems". US Patent 2006/0055592 A1 , 16th March 2006

[9] P.S.H. Leather, J.D. Parsons, 'Equalization for antenna pattern measurements: established technique— new application', IEEE Antennas Propag. Mag., 2003, 45, (2), pp. 154-161

Claims

An apparatus (100; 210; 310) for use in a characterization of a wireless

communication component or of a wireless communication system or of a wireless network in a measurement environment, wherein the apparatus is configured to observe (1 10) the measurement environment for changes of propagation characteristics, and wherein the apparatus is configured to provide ( 20) an updated channel information for compensation of an impact of a wireless channel in the

measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact.

The apparatus according to claim 1 , wherein the apparatus is configured to be more sensitive (130) to changes of the measurement environment than an equipment used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network.

The apparatus according to claim 1 or 2, wherein the apparatus is configured to be more sensitive to changes of the measurement environment than one or more primary receivers (220; 320) used to receive test signals from the wireless communication component or from the wireless communication system or from the wireless network, or wherein the apparatus is configured to be more sensitive to changes of the measurement environment than one or more primary receivers contained within a wireless communication component to be characterized or than one or more primary receivers contained within the wireless communication system to be characterized or than one or more primary receivers contained within the wireless network to be characterized.

The apparatus according to claim 3, wherein the apparatus is configured to detect a change of the measurement environment which is negligible for the one or more primary receivers.

The apparatus according to one of claims 1 to 4, wherein the apparatus is configured to predict an update on the channel information and/or to predict the updated channel information.

The apparatus according to one of claims 1 to 5, wherein the apparatus is configured to report changes of the measurement environment to equipment (305) used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network.

The apparatus according to one of claims 1 to 6, wherein the apparatus is configured to provide an update on the channel information and/or the updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization to equipment (305) used for the characterization of the wireless communication component or of the wireless communication system or of the wireless network.

The apparatus according to one of claims 1 to 7, wherein the apparatus is also configured to characterize the wireless communication component or the wireless communication system or the wireless network in a measurement environment, wherein the apparatus is configured to use the updated channel information when characterizing the wireless communication component or the wireless

communication system or the wireless network in a measurement environment.

A measurement arrangement (200; 300; 600; 700; 800; 900; 1000) for a characterization of an entity under test (230; 330), which is a wireless

communication component or a wireless communication system or a wireless network, in a measurement environment, wherein the measurement arrangement comprises an apparatus (100; 210; 310) according to one of claims 1 to 8; wherein the measurement arrangement further comprises at least one primary antenna (220; 320) configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test; and wherein the measurement arrangement comprises at least one observation antenna (240; 335) configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics.

10. A measurement arrangement (200; 300; 600; 700; 800; 900; 1000) for a

characterization of an entity under test (230; 330), which is a wireless

communication component or a wireless communication system or a wireless network, in a measurement environment, wherein the measurement arrangement comprises an apparatus (100; 210; 310) according to one of claims 1 to 8; wherein the measurement arrangement further comprises at least one primary antenna (220; 320) configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test; and wherein the measurement arrangement comprises at least one observation antenna (240; 335) configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics; wherein the at least one observation antenna is configured or arranged to allow for a detection of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact.

1 1. A measurement arrangement (200; 300; 600; 700; 800; 900; 1000) for a

characterization of an entity under test (230; 330), which is a wireless

communication component or a wireless communication system or a wireless network, in a measurement environment, wherein the measurement arrangement comprises an apparatus (100; 210; 310) according to one of claims 1 to 8; wherein the measurement arrangement further comprises at least one primary antenna (220; 320) configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test; and wherein the measurement arrangement comprises at least one observation antenna (240; 335) configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics; wherein the one or more primary antennas and the one or more observation antennas are arranged or configured such that a response of the one or more observation antennas to a signal reflected or scattered by an obstacle object is greater than a response of the one or more primary antennas to the signal reflected or scattered by an obstacle object.

12. A measurement arrangement (200; 300; 600; 700; 800; 900; 1000) for a

characterization of an entity under test (230; 330), which is a wireless

communication component or a wireless communication system or a wireless network, in a measurement environment, wherein the measurement arrangement comprises an apparatus (100; 210; 310) according to one of claims 1 to 8; wherein the measurement arrangement further comprises at least one primary antenna (220; 320) configured to transmit a test signal to an entity under test, and/or configured to receive a test signal from an entity under test; and wherein the measurement arrangement comprises at least one observation antenna (240; 335) configured to provide an observation signal for the observation of the measurement environment for changes of propagation characteristics; wherein the one or more primary antennas are configured or arranged such that directional characteristics of the one or more primary antennas are directed towards the entity under test. The measurement arrangement according to one of claims 9 to 12, wherein the one or more observation antennas are arranged further away from an entity-under- test region, and/or wherein the one or more observation antennas are configured or arranged to have an omnidirectional characteristic; and/or wherein the one or more observation antennas are configured or arranged to have a directional characteristic (321 , 322; 323; 324; 325) directed towards a region in which a presence of an obstacle object is expected; and/or wherein the observation antennas form an antenna array which provides a stronger signal than the one or more primary antennas; and/or which comprises a higher element count than the one or more primary antennas.

The measurement arrangement according to one of claims 9 to 13, wherein the measurement arrangement comprises an electromagnetic attenuation barrier (325), wherein the at least one primary antenna is arranged on a first side of the electromagnetic attenuation barrier, and wherein the at least one observation antenna is arranged on a second side of the electromagnetic attenuation barrier, such that the electromagnetic attenuation barrier is arranged between the one or more primary probe antennas and the one or more observation antennas.

The measurement arrangement according to claim 14,

wherein the first side of the electromagnetic attenuation barrier is directed towards a region for a placement of an entity under test; and wherein the second side of the electromagnetic attenuation barrier is directed towards a region in which a movement of scattering objects is possible. The measurement arrangement according to one of claims 14 and 15, wherein the electromagnetic attenuation barrier is configured to provide for a transmission attenuation between 1 dB and 100 dB for an electromagnetic wave in an operation frequency range of the measurement arrangement.

The measurement arrangement according to one of claims 9 to 16, wherein the measurement arrangement is configured such that the one or more primary antennas are configured to transmit one or more signals to be received by the entity under test, and such that the one or more observation antennas are configured to receive one or more signals transmitted by the one or more primary antennas, and such that the one or more observation antennas additionally receive one or more signals transmitted by the one or more primary antennas scattered or reflected or refracted or diffracted by an obstacle object in the presence of an obstacle object, wherein the measurement arrangement is configured to estimate a changed channel characteristic, or a change of a channel characteristic, on the basis of one or more signals from the one or more observation antennas, and wherein the arrangement is configured to determine a pre-correction, which is applied to one or more signals transmitted to the entity under test, and which pre- correction serves to at least partially compensate an impact of multipath propagation when transmitting a signal from the one or more primary antennas to the entity under test, on the basis of the estimation of the changed channel characteristic or on the basis of the estimation of the change of the channel characteristic.

The measurement arrangement according to one of claims 9 to 17, wherein the measurement arrangement is configured such that the one or more primary antennas are configured to receive one or more signals transmitted by the entity under test, and such that the one or more observation antennas are configured to receive one or more signals transmitted by the entity under test and such that the one or more observation antennas additionally receive one or more signals transmitted by the entity under test and scattered or reflected or refracted or diffracted by an obstacle object in the presence of an obstacle object, wherein the measurement arrangement is configured to estimate a changed channel characteristic, or a change of a channel characteristic, on the basis of one or more signals from the one or more observation antennas, and wherein the arrangement is configured to determine a post-correction, which is applied to one or more signals transmitted by the entity under test and received by the one or more primary antennas, and which post-correction serves to at least partially compensate an impact of multipath propagation when transmitting a signal from the entity under test to the one or more primary antennas, on the basis of the estimation of the changed channel characteristic or on the basis of the estimation of the change of the channel characteristic. 19. The measurement arrangement according to one of claims 9 to 18, wherein the arrangement is configured to predict an impact of changes of the measurement environment onto signals to be transmitted by the one or more primary antennas or onto signals received by the primary antennas on the basis of the signals received via the observation antennas, and wherein the measurement arrangement is configured to provide an update on the channel information and/or the updated channel information on the basis of the prediction. 20. The measurement arrangement according to claim 19, wherein the measurement arrangement is configured to predict a change of geometry and/or to predict an effect of a change of geometry, which affects multipath propagation characteristics in the measurement environment, on the basis of signals received via the observation antennas, and to provide an update on the channel information and/or the updated channel information on the basis of the prediction. The measurement arrangement according to one of claims 8 to 19, wherein the measurement arrangement is configured to perform a calibration before starting a characterization of an entity under test, in order to determine an initial channel information describing a channel between the one or more primary antennas and the entity under test, and to use the initial channel information in order to compensate for undesired multipath characteristics of the channel among the one or more primary antennas and the entity under test; and wherein the measurement arrangement is configured to provide the updated channel information on the basis of signals received by the one or more

observation antennas during a characterization of the entity under test.

The measurement arrangement according to one of claims 9 to 21 , wherein the measurement arrangement is configured to at least partially cancel (31 1 ) a signal component caused by the transmission of one or more signals from the one or more primary antennas or caused by the transmission of one or more signals from the entity under test from signals received by one or more observation antennas using a knowledge of a previously determined channel information describing a previously determined state of a channel between the one or more primary antennas and the one or more observation antennas, or between the entity under test and the one or more observation antennas, in order to obtain preprocessed observation antenna signals.

The measurement arrangement according to claim 22, wherein the measurement arrangement is configured to provide the updated channel information on the basis of the preprocessed observation antenna signals.

A method (1 100) for use in a characterization of a wireless communication component or of a wireless communication system or of a wireless network in a measurement environment, wherein the method comprises observing (1 1 10) the measurement environment for changes of propagation characteristics, and wherein the method comprises providing (1120) an updated channel information for compensation of an impact of a wireless channel in the measurement environment on the characterization in case of a change of the measurement environment before the change of the measurement environment degrades a characterization result by more than an acceptable impact.

A computer program for performing the method according to claim 24 when the computer program runs on a computer.