Electronically controllable reflector, and system

Abstract

An electronically controllable reflector (RIS), comprising at least one reflector element (RE), each having at least a first antenna element (AE-RX), which is designed to receive a reception signal (DS-TX) as an input signal (S-RX) with a first polarisation (POL1), and an amplifier device (AMP, UNI-AMP, Bi-AMP), which is designed to electronically amplify the input signal (S-RX) and to output it as an output signal (S-TX), and at least a second antenna element (AE-TX), which is designed to transmit the output signal (S-TX) with a second polarization (POL2) as a transmission signal (DS-RX), and a control device (CRTL), which is designed to control the magnitude and / or phase of the output signal (S-TX) using electronic control means in order to form a controllable antenna characteristic of the reflector, the second polarization (POL2) differing from the first polarization (POL1).

Description

[0001] Electronically controllable reflector and system

[0002] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0003] The invention relates to an electronically controllable reflector and a system with an electronically controllable reflector.

[0004] With an electronically controllable reflector (reflective intelligent surface, or RIS for short), radio communication can be improved at higher frequencies, such as 20 GHz and above, and with obstacles between a transmitter and a receiver. A RIS usually consists of several antenna elements whose size and geometry are generally identical. The antenna elements are geometrically arranged on the surface of a carrier, generally following specific rules. For example, round antenna elements are arranged in a hexagonal shape with a pitch of, for example, 0.8 wavelengths.

[0005] An antenna element receives the incoming power wave from the transmitter with a specific gain, depending on the respective antenna characteristics. Electronics within the element reflect this energy and modify its amplitude and / or phase. The control of the electronics in the individual elements is selected so that the sum of the individual reflections from the antenna elements constructively overlap at the receiver.

[0006] By using an electronically controllable reflector, communication between transmitter and receiver can be ensured even in a covert connection (non-line of sight). The range of radio communication, for example, is determined by the level plan, i.e. the sum of power losses from the transmitter to the receiver, taking into account the transmission power, the receiver sensitivity, and the noise power. A level plan also takes into account the reflection losses of the electronically controllable reflector.

[0007] The technical goal is to keep the reflection losses of the electronically controllable reflector as small as possible and, if possible, to achieve a reflection gain.

[0008] In the state of the art, there are several technical possibilities to keep the losses of an electronically controllable reflector small and to increase the reflector reflection gain:

[0009] • Use of a large RIS area with many individual antennas,

[0010] • Use of individual antenna elements with high efficiency, for example with low ohmic losses, and a high antenna gain,

[0011] • Use of control electronics for the individual antenna elements with little reflection loss or even amplification.

[0012] • Joint optimization of the control settings of the individual antenna elements in order to achieve the best possible field strength superposition of the reflections from the individual antenna elements at the location of the receiver.

[0013] The problem is that all these points are subject to limitations and restrictions and further improvements are sought.

[0014] State-of-the-art systems have a latent tendency toward self-oscillation due to the amplification in the RIS control electronics. Until now, the amplification often had to be reduced to the point where the tendency to oscillate no longer existed. This resulted in the losses in the RIS being compensated for, but beyond that, only very small amplifications could be selected.

[0015] This resulted in limitations such as transmit-receive isolation, which determines the ratio between the signal sent into the radiating element and the signal reflected back from it. Directional couplers, isolators, and the like are also associated with the radiating element in this context.

[0016] Furthermore, the inter-element isolation, which represents the isolation from the neighboring RIS antenna elements, is limited.

[0017] The achievable insulation levels are low and highly dependent on the immediate environment. Especially at millimeter-wave frequencies above 20 GHz, manufacturing and component tolerances also have a significant impact on insulation.

[0018] It is therefore an object of the invention to overcome the disadvantages of the prior art by means of a simple and efficient solution.

[0019] The object is achieved by an electronically controllable reflector, comprising at least one reflector element, each containing:

[0020] • at least one first antenna element which is designed to receive a reception signal as an input signal with a first polarization, and

[0021] • an amplifier device which is arranged to electronically amplify the input signal and output it as an output signal, and

[0022] • at least one second antenna element which is arranged to transmit the output signal with a second polarization as a transmission signal, • wherein the second polarization differs from the first polarization, and

[0023] • a control device which is configured to control the output signal in magnitude and / or phase with electronic control means in order to form a controllable antenna characteristic of the reflector, and the control device is further configured to receive a provided polarization control signal,

[0024] • wherein the amplifier device comprises a bidirectional signal amplifier with two adjustable amplification directions, which is configured to adjust the active amplification direction of the bidirectional signal amplifier according to the polarization control signal.

[0025] This allows a significantly higher level of insulation to be achieved, which in turn makes it possible to significantly increase the reinforcement in the RIS elements compared to the state of the art.

[0026] The second polarization is preferably orthogonal to the first polarization, i.e., in the case of linear polarization, preferably rotated by 90°, or in the case of circular polarization, rotating in the other direction, for example, anticlockwise for the first polarization and clockwise for the second polarization, or vice versa. This advantageously decouples the input and output channels of the antenna element.

[0027] As long as the gain is smaller than the isolation, RIS stability, i.e., oscillation-free operation, can be achieved. This applies to both the transmit-receive isolation and the inter-element isolation. The amplifier device comprises a bidirectional signal amplifier, which can amplify signals either in the receive direction or back in the transmit direction.

[0028] The transmitted and received signals have different polarizations. However, it is clear in the present context that, in general, the polarizations of the signals can also be undesirably influenced by various effects during signal transmission, such as reflections. These undesirable effects are not considered separately in the present context, and the aforementioned difference in the polarization of the two signals is not applicable to the inventive feature in which the signal with the second polarization differs from the signal with the first polarization in the method.

[0029] By means of the bidirectional amplifier switched by a control signal, it is therefore possible to easily adapt the polarization when reversing the transmission direction, i.e. when a receiver changes to a transmission mode, in that a control signal from the respective transmitter signals to the reflector in which polarization is being transmitted, whereby the system complexity can be kept simple and bidirectional communication with changing polarization, which is carried out by the reflector, can be carried out in a simple and efficient manner.

[0030] The RIS can also be configured to shape the antenna characteristics of the reflector to minimize the attenuation of the radio signals between the transmitter, reflector, and receiver. This can be achieved by carefully selecting individual antenna elements and adjusting their control in magnitude and / or phase accordingly. The electronically controllable reflector can have a large number of reflector elements, for example, 10, 50, 100, or even more.

[0031] The antenna elements can be realized in different arrangements.

[0032] For example, the antenna elements for receiving and transmitting can be arranged alternately to form the reflector.

[0033] Alternatively, two reflectors can be arranged side by side. One of these reflectors, with antenna elements, serves as a receiver with a first polarization, and the other reflector serves as a transmitter with a second polarization. Or, with linear polarization, the other reflector can be mounted rotated 90° relative to the receiver.

[0034] The solution enables high gain and stable operation while avoiding amplifier oscillation.

[0035] Furthermore, the number of antenna elements can be reduced while maintaining the same reflector effect. For example, a gain of 3 dB halves the number of required elements, or halves the area required by the RIS.

[0036] The smaller number of required elements increases the beamwidth of the RIS's directional characteristic toward the receiver. This requires less precise "aiming," meaning movements in the S scenario have less impact, and finding radio participants, such as by scanning in two spatial angles, requires fewer iterations and is therefore faster.

[0037] The solution is also advantageous for optimizing energy consumption. Electronic control means for controlling the magnitude and / or phase of signals are known in the art, for example, electronic phase shifters, voltage dividers, or electronic amplifiers in digital or analog versions. Digital phase shifters, for example, can control two or more states.

[0038] In a further development of the invention, it is provided that the reflector is designed to operate at an operating frequency of at least 20 GHz.

[0039] Particularly at operating frequencies of an RIS of over 20 GHz, a sufficiently high number of antenna elements can be realized.

[0040] In a further development of the invention, it is provided that the at least one first antenna element and the at least one second antenna element are formed by a common antenna structure.

[0041] By using bidirectional amplifiers instead of unidirectional amplifiers, which are used in alternating RIS elements, the RIS can receive horizontally and reflect vertically at one time and with reversed polarization at another time. The advantage of this is that if the RIS knows which polarization is currently being received as the input signal, additional elements configured accordingly in the polarization can contribute to the amplification.

[0042] From the radio system's perspective, there are no significant differences in the channel characteristics for uplink and downlink. There are no restrictions on the radio system used.

[0043] Furthermore, from the radio system's perspective, the use of a specific polarization is advantageous, as simple terminal devices often only support one polarization, or environmental conditions exist that favor or weaken one polarization. Accordingly, the bidirectionally amplifying RIS enables the use of the best connection in each case.

[0044] A further extension is provided by control electronics, which can on the one hand act purely passively, and on the other hand can also work in an amplifying manner (uni- and / or bidirectionally).

[0045] The advantage of this solution is that it allows you to choose whether or not amplification, and thus more supply power, is required. The RIS can be configured and operated in an energy-optimized manner with sufficient performance. This feature is particularly relevant for applications requiring high availability, i.e., 24 / 7 operation.

[0046] This allows the reflector to be pre-adjusted to a preferred polarization plane and reception losses can be reduced.

[0047] Electronic means for adjusting the polarization are known in the art, such as the use of separate feed points on a corresponding antenna, such as a patch antenna, or the use of orthogonally arranged dipole antennas.

[0048] The object is achieved by a system comprising a radio transmitter for transmitting a data transmission signal and electronic means for controlling the polarization of the data signal, an electronically controllable reflector according to one of the preceding claims for reflecting the data transmission signal, a radio receiver for receiving the reflected data signal and a system control device connected to the radio transmitter by means of communication, wherein the radio transmitter is set up to set a predetermined polarization with its electronic means and to transmit information about this polarization to the system control device with the aid of the communication means, and the system control device is set up to set the polarization on the reflector when receiving the data signal with the aid of the respective electronic means for setting the polarization.

[0049] This allows the reflector to be pre-adjusted to a preferred polarization and reception losses can be reduced.

[0050] In a further development of the invention, it is provided that the system comprises a first radio transmitter according to the system according to the invention and a second radio transmitter, as well as a first radio receiver according to the system according to the invention and a second radio receiver, wherein the first radio transmitter and the first radio receiver form a first transceiver, and the second radio transmitter and the second radio receiver form a second transceiver, and a controllable reflector according to the system according to the invention, which is configured to connect the first transceiver to the second transceiver by means of a radio connection via the reflector, and the first radio transmitter is configured to transmit a first data signal with a first polarization at a first time, and the second radio transmitter is configured to transmit a second data signal with a second polarization at a subsequent second time,which differs from the first polarization.,

[0051] The reflector can be configured so that the first transceiver transmits and receives on the first polarization, and the second transceiver transmits and receives on the second polarization. This means that expanding the radio system with an RIS does not require any changes or adaptations to the existing transmission technology between the transceivers. These can continue to use the same antennas, and thus the same polarizations, for transmitting and receiving.

[0052] In a further development of the invention, it is provided that the transmitter is designed to transmit polarization information relating to the first polarization to the controllable reflector according to the invention, and the reflector is designed to receive the polarization information and to adjust the amplification direction of the bidirectional signal amplifier so that it corresponds to the first polarization.

[0053] This allows the polarization to be adjusted in a simple manner according to the polarization of the signal sent by the transmitter by using the bidirectional signal amplifier.

[0054] In other words, this achieves that the transmit path in the combined antenna becomes the receive path of the combined antenna, and the receive path becomes the transmit path of the combined antenna.

[0055] In the combined antenna, a first polarization direction is provided for a switchable transmit / receive path, and a second polarization direction is provided for the second switchable transmit / receive path, wherein the first polarization direction differs from the second polarization direction, preferably the first polarization direction and the second polarization direction are orthogonal to one another.

[0056] This formulation, as a further development of the invention, can also be understood as an independent system, independent of the system descriptions as stated above. The invention is explained in more detail below with reference to an exemplary embodiment shown in the accompanying drawings. The drawings show:

[0057] Fig. 1 A symbolic representation of an electronically controllable reflector,

[0058] Fig. 2 is a block diagram of the electronically controllable reflector,

[0059] Fig. 3 is a diagram of an antenna element according to the prior art,

[0060] Fig. 4 shows an embodiment of an antenna element with an inserted unidirectional amplifier and two antenna connections for different polarizations,

[0061] Fig. 5 shows an embodiment of two antenna elements, each with an inserted unidirectional amplifier and two antenna connections for different polarizations,

[0062] Fig. 6 shows an exemplary embodiment of an antenna element with an inserted bidirectional amplifier and two antenna connections for different polarizations.

[0063] Fig. 1 shows symbolically an example of an electronically controllable reflector RIS with a plurality of round antenna elements AE, which are arranged on a planar circuit carrier with a hexagonal contour.

[0064] Fig. 2 shows a block diagram of the electronically controllable reflector RIS and a radio communication system.

[0065] The electronically controllable reflector RIS comprises a plurality of reflector elements RE, each of which has a receiving antenna element AE-RX and a transmitting antenna element AE-TX. A reflector RIS can comprise a plurality of reflector elements RE.

[0066] Each reflector element RE has a first antenna element AE-RX which is configured to receive a signal DS-TX transmitted by a transmitter TX as a received signal with a first polarization POL1 as an input signal S-RX.

[0067] Furthermore, an amplifier device AMP is provided which is designed to electronically amplify the input signal S-RX and to output it as an output signal S-TX to the transmitting antenna element AE-TX.

[0068] Each reflector element RE has a second antenna element AE-TX, which is designed to send the output signal S-TX with a second polarization POL2 as a transmission signal DS-RX to a receiver RX.

[0069] Furthermore, a control device CRTL is provided which is designed to control the output signal S-TX in magnitude and / or phase with electronic control means in order to form a controllable antenna characteristic of the reflector and in such a way that the second polarization POL2, for example a vertical polarization, differs from the first polarization POL1, for example a horizontal polarization.

[0070] The amplifier device AMP can be included in a reflector element RE.

[0071] The reflector RIS is preferably dimensioned to operate at an operating frequency of at least 20 GHz.

[0072] The first antenna element AE-RX and the second antenna element AE-TX are optionally formed by a common antenna structure AE, which, together with the amplifier device AMP, forms the reflector element RE. The amplifier device AMP can comprise a bidirectional signal amplifier.

[0073] In a special embodiment, the amplifier device AMP is controlled so that the antenna element AE-RX or AE-TX, which ensures the better transmission quality of the signal DS-TX with polarization POL1, is used as the receiving element. At the same time, the other antenna element AE-TX or AE-RX is used to transmit the signal DS-RX with polarization POL2. The setting or control is optionally carried out using a control signal POL-C, which is transmitted from the transmitter TX. The control POL-C of the system control device CTRL is shown in the figure separately from the data transmission signal DS-TX. This representation is only a logical representation, because the data transmission signal DS-TX and the signal for controlling the polarization POL-C can optionally be transmitted over the same radio channel, but alternatively also over separate transmission channels.

[0074] In a further embodiment, a system comprises a radio transmitter TX for transmitting a data transmission signal DS-TX with electronic means for controlling the polarization POL1 of the data signal, an electronically controllable reflector RIS according to the invention for reflecting the data transmission signal DS-TX, a radio receiver RX for receiving the reflected data signal DS-RX and a system control device CTRL.

[0075] The system control device CTRL is designed to adjust the polarization POL2 when transmitting the data signal DS-RX at the reflector RIS by means of the respective electronic means for adjusting the polarization.

[0076] Electronic means for adjusting the polarization are known in the art, such as the use of separate feed points on a corresponding antenna, such as a patch antenna, or the use of orthogonally arranged dipole antennas.

[0077] The radio transmitter TX can further be configured to transmit a first data signal with a first polarization at a first time and to transmit a second data signal with a second polarization that differs from the first polarization at a subsequent second time.

[0078] The controllable reflector can be configured to reflect the first and second data signals to the radio receiver, which receives the two signals.

[0079] The system shown only represents a unidirectional signal path from the transmitter TX via the reflector RIS to the receiver RX. However, it is clear that the system can also operate bidirectionally, and the transmitter TX and the receiver RX can each be formed by a transceiver that can send and receive data. It also implies that a system control device CTRL is controlled by the transmitter of the transceiver, which includes the receiver RX, in the corresponding transmit mode. In other words, the system control device CTRL can optionally be connected to the transceiver of the transmitter TX as well as to the transceiver of the receiver RX. For the sake of clarity, this functionality is not shown.

[0080] It is also advantageous if the RIS is connected to only one of the transceivers, namely if the transceiver is part of a "base station." The base station knows all data regarding transmission and reception times, as well as the transmission directions (uplink / downlink) of all participants.

[0081] In a specific embodiment, a system is provided, comprising a radio transmitter TX for transmitting a data transmission signal DS-TX with electronic means for controlling the polarization POLI of the data signal, an electronically controllable reflector RIS for reflecting the data transmission signal DS-TX, a radio receiver RX for receiving the reflected data signal DS-RX and a system control device CTRL connected to the radio transmitter TX with a communication means.

[0082] The radio transmitter TX is designed to set a predetermined polarization POL1 with its electronic means and to transmit information about this polarization POL1 to the system control device CTRL using the communication means.

[0083] A predetermined polarization POL1 is set on the radio transmitter TX using its electronic means.

[0084] This polarization POL1 is transmitted to the system control device CTRL by means of the communication means.

[0085] The system control device CTRL is designed to adjust the polarization POL1 on the reflector RIS upon receiving the data signal DS-TX by means of the respective electronic means for adjusting the polarization.

[0086] In a further specific embodiment, a system is provided comprising a first radio transmitter TX and a second radio transmitter, as well as a first radio receiver RX and a second radio receiver.

[0087] The first radio transmitter TX and the first radio receiver RX form a first transceiver.

[0088] The second radio transmitter and the second radio receiver form a second transceiver.

[0089] A controllable reflector RIS is configured to connect the first transceiver to the second transceiver via a radio link and the reflector RIS. The first radio transmitter TX is configured to transmit a first data signal with a first polarization at a first time.

[0090] The second radio transmitter is configured to transmit a second data signal with a second polarization that differs from the first polarization at a subsequent second point in time.

[0091] In Fig. 3 an antenna element according to the prior art is shown.

[0092] An antenna element AE receives a signal, feeds the signal to a divider circuit DIV, amplifies the received signal with a unidirectional amplifier UNI-AMP, and feeds the amplified signal back to the antenna element AE for radiation via the divider DIV.

[0093] If the gain of the UNI-AMP amplifier is set too high, this can lead to undesired oscillation of the arrangement.

[0094] Fig. 4 shows an exemplary embodiment of an antenna element with an inserted unidirectional amplifier and two antenna connections for different polarizations.

[0095] An antenna element AE receives a signal via a first feed connection, which only detects a vertical polarization plane VER, amplifies the received signal with a unidirectional amplifier UNI-AMP, and feeds the amplified signal back to the antenna element AE for radiation, but via a second feed connection with a different, horizontal polarization plane HÖR compared to the polarization plane VER of the first feed connection.

[0096] The vertical polarization plane VER corresponds to the first polarization POL1 according to the previous figures, and the horizontal polarization plane HÖR corresponds to the second polarization POL2 according to the previous figures, which is different from the first polarization POL1.

[0097] Fig. 5 shows an exemplary embodiment for two antenna elements, each with an inserted unidirectional amplifier and two antenna connections for different polarizations HÖR and VER.

[0098] The arrangement corresponds to a duplicate arrangement according to the previous figure, but a separate signal path is provided for two different polarization planes HÖR and VER.

[0099] Fig. 6 shows an exemplary embodiment of an antenna element with an inserted bidirectional amplifier BI-AMP and two antenna connections for different polarizations of a common, combined antenna AE, wherein the bidirectional amplifier BI-AMP provides a single signal path for both feed connections for a first, horizontal and a second, vertical polarization plane HÖR and VER.

[0100] The bidirectional signal amplifier BI-AMP can, for example, be realized by two anti-parallel connected unidirectional amplifiers with the aid of controllable switches, i.e. two unidirectional amplifiers which are connected to each other in anti-parallel and switchable manner via two high-frequency switches (SPDT, English "single pole, double throw").

[0101] In other words, the nodes of the bidirectional amplifier BI-AMP shown in Fig. 6 can each be replaced by SPDT switches and controlled accordingly to set only one active amplification direction of the bidirectional signal amplifier BI-AMP.

[0102] Alternatively, the two anti-parallel connected unidirectional amplifiers of the bidirectional signal amplifier BI-AMP can each be operated by activation or deactivation in the respective branches with a unidirectional amplifier in order to effect a switching of the active amplification direction of the bidirectional signal amplifier BI-AMP.

[0103] This can be done by applying or disconnecting a supply voltage, or by changing control voltages, for example to set the respective operating point on the respective unidirectional amplifier in order to set only one active amplification direction of the bidirectional signal amplifier BI-AMP.

[0104] By changing the active amplification direction of the bidirectional signal amplifier BI-AMP, the change in polarization direction can be achieved.

[0105] The transmit path in the combined antenna AE thus becomes the receive path of the combined antenna AE , and the receive path becomes the transmit path of the combined antenna AE .

[0106] In the combined antenna AE for the two polarization planes HÖR and VER, the first polarization direction HÖR is provided for a switchable transmit / receive path, and the second polarization direction VER is provided for the second switchable transmit / receive path, wherein the first polarization direction HÖR differs from the second polarization direction VER, preferably the first polarization direction HÖR and the second polarization direction VER are orthogonal to each other. List of reference symbols:

[0107] AE , AE-RX,

[0108] AE-TX antenna element

[0109] DIV directional coupler

[0110] DS-RX signal sent to a receiver, transmit signal of the reflector

[0111] DS-TX signal sent by a transmitter TX, received signal of the reflector

[0112] LISTEN to horizontal polarization

[0113] POLI, POL2 polarization

[0114] POL-C polarization control signal

[0115] RIS electronically controllable reflector

[0116] AMP, UNI-AMP,

[0117] BI-AMP amplifier

[0118] RE reflector element

[0119] RX receiver

[0120] TX transmitter

[0121] VER vertical polarization

Claims

Patent claims 1. Electronically controllable reflector (RIS) comprising a plurality of reflector elements (RE), each comprising a first antenna element (AE-RX) which is configured to receive a received signal (DS-TX) as an input signal (S-RX) with a first polarization (POL1), and an amplifier device (AMP, UNI-AMP, BI-AMP) which is configured to electronically amplify the input signal (S-RX) and output it as an output signal (S-TX), and a second antenna element (AE-TX) which is configured to transmit the output signal (S-TX) with a second polarization (POL2) as a transmitted signal (DS-RX), wherein the second polarization (POL2) differs from the first polarization (POL1), and a control device (CRTL) which is configured to electronically control the output signal (S-TX) in magnitude and / or phase. control means to form a controllable antenna characteristic of the reflector, characterized inthat the control device (CRTL) is further configured to receive a provided polarization control signal (POL-C), wherein the amplifier device (AMP) comprises a bidirectional signal amplifier (BI-AMP) with two adjustable amplification directions, which is configured to adjust the active amplification direction of the bidirectional signal amplifier (BI-AMP) according to the polarization control signal (POL-C).

2. Reflector (RIS) according to the preceding claim, wherein the reflector (RIS) is adapted to operate at an operating frequency of at least 20 GHz.

3. Reflector (RIS) according to one of the preceding claims, wherein the at least one first antenna element (AE-RX) and the at least one second antenna element (AE-TX) are formed by a common antenna structure (AE).

4. System comprising a radio transmitter (TX) for transmitting a data transmission signal (DS-TX) and electronic means for controlling the polarization (POL1) of the data signal, an electronically controllable reflector (RIS) according to one of the preceding claims for reflecting the data transmission signal (DS-TX), a radio receiver (RX) for receiving the reflected data signal (DS-RX), and a system control device (CTRL) connected to the radio transmitter (TX) by a communication means, wherein the radio transmitter (TX) is configured to set a predetermined polarization (POL1) with its electronic means and to transmit information (POL-C) about this polarization (POL1) to the system control device (CTRL) using the communication means, and the system control device (CTRL) is configured toto adjust the polarization (POL1) on the reflector (RIS) when receiving the data signal (DS-TX) using the respective electronic means for adjusting the polarization.

5. System according to the preceding claim, comprising a first radio transmitter (TX) according to the system of the preceding claim and a second radio transmitter, as well as a first radio receiver (RX) according to the system of the preceding claim and a second radio receiver, wherein the first radio transmitter (TX) and the first radio receiver (RX) form a first transceiver, and the second radio transmitter and the second radio receiver form a second transceiver, and a controllable reflector (RIS) according to the system of the preceding claim, which is designed to connect the first transceiver to the second transceiver by means of a radio Connection and the reflector (RIS), and the first radio transmitter (TX) is configured to transmit a first data signal with a first polarization at a first time, and the second radio transmitter is configured to transmit a second data signal with a second polarization, which differs from the first polarization, at a subsequent second time.

6. System according to one of the preceding claims, wherein the transmitter (TX) is configured to transmit polarization information (POL-C) relating to the first polarization (POL1) to the controllable reflector (RIS) according to one of claims 1 to 3, and the reflector is configured to receive the polarization information (POL-C) and to adjust the amplification direction of the bidirectional signal amplifier (BI-AMP) so that it corresponds to the first polarization (POL1).

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