WO2022074118A1

WO2022074118A1 - Re-configurable repeater device and access node reference signals

Info

Publication number: WO2022074118A1
Application number: PCT/EP2021/077694
Authority: WO
Inventors: Jose Flordelis; Erik Bengtsson; Kun Zhao; Olof Zander; Fredrik RUSEK
Original assignee: Sony Group Corporation; Sony Europe B.V.
Priority date: 2020-10-08
Filing date: 2021-10-07
Publication date: 2022-04-14

Abstract

Re-configurable repeater device and access node reference signals A wireless communication device can transmit a request to an access node to adjust a frequency of occurrence of downlink reference signals. This may depend on whether or not the wireless communication device is being served via a re-configurable repeater device.

Description

Re-configurable repeater device and access node reference signals

TECHNICAL FIELD

Various examples generally relate to operating a wireless communication device and an access node in the presence of a re-configurable repeater device. Various examples specifically relate to adjusting a reference-signal transmission.

BACKGROUND

To increase a coverage area for wireless communication, it is envisioned that re- configurable repeater devices (RRD) will become commonplace. Different kinds of RRDs are known.

A first kind of RRD is a re-configurable reflective device, sometimes also referred to as a reflecting large intelligent surface (LIS). See, e.g., Sha Hu, Fredrik Rusek, and Ove Edfors. "Beyond massive MIMO: The potential of data transmission with large intelligent surfaces." /EEE Transactions on Signal Processing 66.10 (2018): 2746- 2758. An LIS can be implemented by an array of antennas that reflect incident electromagnetic waves/signals or a meta-surface. The array of antennas can be semipassive. Semi-passive can correspond to a scenario in which the antennas do not provide signal amplification but can impose a variable phase shift and/or attenuation. An input spatial direction from which incident signals (incident onto the RRD) on a data carrier are accepted and an output spatial direction into which the incident signals are reflected can be re-configured, by changing a phase relationship between the antennas.

A second kind of RRD is a so-called smart repeater having an amplify-and-forward functionality. Amplify-and-forward functionality is different to a decode-and-forward functionality in that it is not required to translate RF signals into the baseband and decode. This simplifies the hardware design of smart repeaters when compared to decode-and-forward relays. On the other hand, noise imposed on the signal is also amplified and forwarded. SUMMARY

Accordingly, there is a need of improved techniques for operating nodes and devices in the presence of an RRD. Specifically, there is a need for techniques to reduce control-signaling overhead.

This need is met by the features of the independent claims. The features of the dependent claims define examples.

A method of operating a UE is provided. The UE can connect to a communications network. The UE is configured to communicate with an access node of the communications network via an RRD. The RRD is re-configurable to provide multiple spatial filters. Each one of the multiple spatial filters is associated with a respective input spatial direction from which incident signals on a data carrier are accepted, as well as with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD. The method includes transmitting a request to adjust the frequency of occurrence of downlink reference signals to the access node. Said transmitting is based on at least one decision criterion. The downlink reference signals are transmitted by the access node to the UE.

For example, it would be possible that at least one decision criterion includes information indicating whether or not the UE is being served via the RRD when communicating between the wireless communication device and the BS. Other decision criteria are possible, e.g., a state of a beam management procedure at the UE.

A computer program or a computer-program product or a computer-readable storage medium includes program code. The program code can be loaded and executed by least one processor. Loading and executing the program code can cause the at least one processor to perform a method of operating a UE. The UE can connect to a communications network. The UE is configured to communicate with an access node of the communications network via an RRD. The RRD is re-configurable to provide multiple spatial filters. Each one of the multiple spatial filters is associated with a respective input spatial direction from which incident signals on a data carrier are accepted, as well as with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD. The method includes transmitting a request to adjust the frequency of occurrence of downlink reference signals to the access node. Said transmitting is based on at least one decision criterion. The downlink reference signals are transmitted by the access node to the UE.

A wireless communication device connectable to a communications network is provided. The wireless communication device is configured to communicate with an access node of the communications network via a re-configurable repeater device, RRD, the RRD being re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD. The wireless communication device comprising control circuitry configured to, based on at least one decision criterion, transmit, to the access node, a request to adjust a frequency of occurrence of downlink reference signals transmitted by the access node to the wireless communication device.

A method is provided. The method includes transmitting and/or receiving (communicating), between a wireless communication device and an access node of a communications network, a control message. The control message is indicative of reserved resources for use by the wireless communication device to perform a beam management procedure. The beam management procedure includes alignment of beams between the wireless communication device and a reconfigurable repeater device, RRD, via which the access node and the wireless communication device communicate.

For example, the method could be executed by the UE and/or the access node.

It would then be possible to implement a beam management procedure at the wireless communication device by transmitting and/or receiving reference signals to or from the RRD.

A computer program or a computer-program product or a computer-readable storage medium includes program code. The program code can be loaded and executed by least one processor. Loading and executing the program code can cause the at least one processor to perform a method. The method includes transmitting and/or receiving, between a wireless communication device and an access node of a communications network, a control message. The control message is indicative of reserved resources for use by the wireless communication device to perform a beam management procedure. The beam management procedure includes alignment of beams between the wireless communication device and a reconfigurable repeater device via which the access node and the wireless communication device communicate.

A node comprising control circuitry configured to communicate, between a wireless communication device and an access node of a communications network, a control message. The control message is indicative of reserved resources for use by the wireless communication device to perform a beam management procedure. The beam management procedure includes alignment of beams between the wireless communication device and a reconfigurable repeater device via which the access node and the wireless communication device communicate.

A method of operating a re-configurable repeater device, RRD is provided. The RRD is re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD. The method includes temporarily, during a testing duration, divert or deactivate reflecting or amplifying incident signals towards a wireless communication device or towards an access node.

For example, the RRD may receive a respective request to temporarily divert or deactivate from the wireless communication device and/or the access node.

A method of operating a node - e.g., a UE and/or an access node - includes providing a respective request to temporarily divert or deactivate reflecting or amplifying incident signals to the RRD. This can be in response to a need to determine whether or not the wireless communication device is being served via the RRD.

A computer program or a computer-program product or a computer-readable storage medium includes program code. The program code can be loaded and executed by least one processor. Loading and executing the program code can cause the at least one processor to perform a method of operating a re-configurable repeater device, RRD. The RRD is re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD. The method includes temporarily, during a testing duration, divert or deactivate reflecting or amplifying incident signals towards a wireless communication device or towards an access node.

A re-configurable repeater device, RRD is provided. The RRD is re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier are accepted and with a respective output spatial direction into which incident signals are reflected or amplified by the RRD. The RRD includes a control circuitry configured to temporarily, during a testing duration, divert or deactivate reflecting or amplifying incident signals towards a wireless communication device or towards an access node.

It is to be understood that the features mentioned above and those yet to be explained below may be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a communication system including a base station (BS) and a wireless communication device (UE) according to various examples.

FIG. 2 schematically illustrates details of the communication system of FIG. 1 .

FIG. 3 schematically illustrates beamforming at the BS according to various examples, wherein FIG. 3 schematically illustrates a beam-establishment stage of a beam management process according to various examples.

FIG. 4 schematically illustrates beamforming at the BS according to various examples, wherein FIG. 4 schematically illustrates a beam-tracking stage of a beam management process according to various examples.

FIG. 5 schematically illustrates beamforming at the BS according to various examples, wherein the BS selects a beam directed towards an RRD. FIG. 6 schematically illustrates an RRD according to various examples.

FIG. 7 schematically illustrates beamforming at the BS on multiple spatial filters and an RRD according to various examples, wherein FIG. 7 schematically illustrates a beam-establishment stage of the beam management process at the RRD and the UE.

FIG. 8 schematically illustrates beamforming at the BS and the multiple spatial filters at the RRD according to various examples, wherein FIG. 8 schematically illustrates beam-tracking stage of the beam management process at the RRD and the UE.

FIG. 9 is a flowchart of a method according to various examples.

FIG. 10 is a flowchart of a method according to various examples.

FIG. 11 is a flowchart of a method according to various examples.

FIG. 12 is a signaling diagram according to various examples.

FIG. 13 is a flowchart of a method according to various examples.

DETAILED DESCRIPTION OF THE DRAWINGS

Some examples of the present disclosure generally provide for a plurality of circuits or other electrical devices. All references to the circuits and other electrical devices and the functionality provided by each are not intended to be limited to encompassing only what is illustrated and described herein. While particular labels may be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation for the circuits and the other electrical devices. Such circuits and other electrical devices may be combined with each other and/or separated in any manner based on the particular type of electrical implementation that is desired. It is recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, a graphics processor unit (GPU), integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, any one or more of the electrical devices may be configured to execute a program code that is embodied in a non-transitory computer readable medium programmed to perform any number of the functions as disclosed.

In the following, examples of the disclosure will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of examples is not to be taken in a limiting sense. The scope of the disclosure is not intended to be limited by the examples described hereinafter or by the drawings, which are taken to be illustrative only.

The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling. A coupling between components may also be established over a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

Techniques are described that facilitate wireless communication between nodes. A wireless communication system includes a transmitter node and one or more receiver nodes. The nodes communicate on a data carrier. In some examples, the wireless communication system can be implemented by a wireless communication network, e.g., a radio-access network (RAN) of a Third Generation Partnership Project (3GPP)- specified cellular network (NW). In such case, the transmitter node can be implemented by an access node such as a BS of the RAN, and the one or more receiver nodes can be implemented by UEs. It would also be possible that the transmitter node is implemented by a UE and the one or more receiver nodes are implemented by a BS and/or further UEs.

According to various examples, it is possible to use multi-antenna techniques. Multiantenna techniques are sometimes used to enhance reliability and/or throughput of wireless communication. Here, the transmitter node and the receiver node both include multiple antennas that can be operated in a phase-coherent manner. Thereby, a signal can be transmitted redundantly (diversity multi-antenna mode) along multiple spatial data streams, or multiple signals can be transmitted on multiple spatial data streams (spatial multiplexing multi-antenna operational mode). It is possible to use beamforming: here, spatial data streams can be defined by focusing the transmission energy for transmitting (transmit beam, TX beam) and/or the receive sensitivity for receiving (receive beam, RX beam) to at least one spatial direction, i.e., having a tailored spatial profile. For beamforming, the process of identifying the appropriate beams is often referred to beam management. Various techniques described herein are concerned with beam management.

The techniques described herein are concerned with beam management at the BS. Beam management at the BS helps identify one or more TX beams and/or one or more RX beams to be used by the BS. The BS beams can be directed to communicate with the UE and, optionally, when the UE is being served by the RRD, towards the RRD.

Further techniques described herein are concerned with beam management at the UE. Beam management at the UE helps to identify one or more RX beams and/or one or more RX beams to be used by the UE. The beam management at the UE helps to identify UE beams directed towards the BS and, optionally, towards the RRD when the UE is being served by the RRD.

Still further techniques described herein are concerned with beam management at an RRD. Beam management at the RRD can facilitate determining one or more spatial filters to be applied by the RRD for reflecting and/or amplifying incident signals.

According to various examples, two nodes - e.g., the BS and the UE - can communicate with each other via an RRD. The RRD may include an antenna array. The RRD may include a meta-material surface. In examples, an RRD may include a reflective antenna array (RAA). The RRD can implement a smart repeater functionality using amplify-and-forward procedures. To forward an incident signal, the RRD may not decode the signal. The RRD may not translate an incident signal into the baseband.

As a general rule, the RRD is configured to employ multi-antenna techniques. In particular, the RRD is reconfigurable to provide multiple spatial filters. Thereby, a spatial data stream between two nodes - e.g., the BS and the UE - can be diverted. Each one of the multiple spatial filters is associated with at least one respective input spatial direction from which incident signals on a respective data carrier are accepted, as well as with at least one respective output spatial direction into which incident signals are reflected or amplified by the RRD. Each output spatial direction is associated with a respective beam. The RRD thereby implements beamforming. The process of selecting the appropriate spatial filter at the RRD is hereinafter also referred to as beam management.

There are many schools of thought for how RRDs should be integrated into 3GPP- standardized RANs. In an exemplary case, the NW operator has deployed the RRDs and is therefore in full control of the RRD operations. The UEs, on the other hand, may not be aware of the presence of any RRD, at least initially, i.e., it is transparent to a UE whether it communicates directly with the BS or via an RRD. The RRD essentially functions as a coverage-extender of the BS. It can provide strong reflections. The BS may have established a control link with the RRD. According to another exemplary case, it might be a private user or some public entity that deploys the RRD. Further, it may be that the UE, in this case, controls RRD operations. The BS, on the other hand, may not be aware of the presence of any RRD and, moreover, may not have control over it/them whatsoever. The UE may gain awareness of the presence of RRD by means of some short-range radio technology, such as Bluetooth, wherein Bluetooth may refer to a standard according to IEEE 802.15, or WiFi, wherein WiFi may refer to a standard according to IEEE 802.11 , by virtue of which it may establish the control link with the RRD. The control link can thus be on an auxiliary carrier which may be on the same or a different frequency than the data carrier. In a further exemplary case, neither the UE nor the BS are aware of the presence of the RRD. The RRD may be transparent with respect to a communication between the UE and the BS on a data carrier. The RRD may gain awareness of the UE and/or the BS and re-configure itself based on information obtained from the UE and/or BS.

The three exemplary cases described above are summarized in TAB. 1 below.

TAB. 1 : Scenarios for RRD integration into cellular NW. The various examples described herein can use, e.g., scenario A and/or scenario B.

The techniques described herein can be used to configure a reference-signal transmission of reference signals (RSs; sometimes also referred to as pilot signals or synchronization signals or beacon signals). Specifically, the techniques can be used to configure an RS transmission of downlink (DL) RSs transmitted by the BS. The RS transmission can be helpful for beam management at the BS. It would also be possible that the RS transmission is helpful for beam management at the BS. For instance, the RS transmission can be used for beam management at the BS, to determine one or more BS beams, based on feedback signaling from the UE. The RS transmission can be used for beam management at the UE, to determine one or more UE beams based on one or more receive properties of the DL RSs.

As a general rule, the RSs can have a predefined signal shape and/or symbol sequence. The RSs can have predefined transmit properties such as, e.g., transmit amplitude or phase, or even precoding. Thus, by using the RSs, one or more second nodes, e.g., the RRD, can obtain information on the channel between the first node and the respective one of the one or more second nodes. Such information may be obtained based on feedback signaling from a receiving node. As a general rule, various kinds and types of RSs can be subject to the techniques described herein. For instance, RSs that are not associated with one or more specific UEs - e.g., a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) broadcasted in a synchronization signal block (SSB) - can be subject to the techniques described herein. Broadcasted RSs can be transmitted on a Physical Broadcast Channel (PBCH). Alternatively, or additionally, it would be possible to apply the techniques described herein to RSs that are associated with one or more specific UEs; an example would be a Channel State Information (CSI)-RS. Such reference signals can be transmitted in time frequency resources allocated to the one or more specific UEs. Other examples of reference signals include sounding reference signals (SRS), e.g., communicated from a UE to a BS in the uplink direction.

In particular, according to various techniques described herein, it is possible to configure RS transmission, in particular to dynamically configure an on-demand RS transmission. For example, CSI-RSs may be flexibly activated or deactivated, or - more generally - the frequency of occurrence - i.e. , the time-domain density - of the respective transmission may be adjusted.

As a general rule, various decision criteria are conceivable to adjust the frequency of occurrence of the RS transmission. In particular, it is possible that at least one decision criterion is used.

According to various examples, the at least one decision criterion to adjust the frequency of occurrence of the RS transmission of DL RSs is dependent on the behavior of the UE. As a general rule, the decision criterion can be UE-centric. i.e., one or more parameters observed at the UE by the UE can be taken into account.

Specifically, it would be possible to take into account an impact of the RRD on the behavior of the UE.

Various techniques are based on the finding that an RRD can sometimes be comparably static - i.e., exhibit reduced mobility - when compared to a UE. Therefore, DL RSs transmitted by the BS to the UE via the RRD may sometimes have limited value or may even be unnecessary for beam management at the BS. Further, it has been found that such DL RSs transmitted by the BS may also have limited value or may even be unnecessary for beam management at the UE; this can be the case where the beam management of the UE relies on other sources of RSs, e.g., RSs transmitted by the RRD. Further, it has been found that there can be tendencies that the UE level of change of orientation (i.e., how fast or how often the UE changes orientation) can significantly vary for UE’s that are being served via an RRD. An example would be a virtual-reality scenario with a head-mounted or backpack mounted UE. Accordingly, according to various examples, it would be possible that a high frequency of occurrence of DL RSs transmitted by the BS for beam management at the UE may sometimes not be required, depending on the level of change of orientation of the UE. Then, it is possible to free-up resources on the spectrum by reducing the frequency of occurrence of the RSs.

Where the positioning of the BS with respect to the RRD is comparably static, the beam management at the BS toward the RRD can also be comparably static. Thus, also the BS may not require feedback signaling from the UE indicative of one or more receive properties of DL RS. On the other hand, the UE is mobile and thus is typically required to continuously adjust the UE beams, either towards the RRD when being served via the RRD or towards the BS.

As a general rule, there can be three scenarios for beam management using DL RSs.

These are summarized in TAB. 1A.

TAB. 1 A: various options for use of RSs for beam management at the UE (scenario II and III) and the BS (scenario I).

Various techniques are based on the finding that, depending on at least one UE-centric decision criterion, it is sometimes possible to adjust the frequency of occurrence for one or more RS transmissions according to scenarios l-lll according to TAB. 1 A. Here, it has been found that, sometimes, for one and the same state of operation at the UE, it would be possible to increase the frequency of occurrence for, e.g., the RS transmission according to scenario I of TAB. 1A, while the frequency of occurrence for the RS transmission according to scenario II of TAB. 1A is decreased - and vice versa. Oftentimes, the frequency of occurrence for the scenario according to scenario III of TAB. 1 A will remain fixed.

According to various examples, it is possible that the UE transmits to the BS a request to adjust the frequency of occurrence of DL RSs transmitted by the BS to the UE. This transmitting of the request can be based on at least one decision criterion. The BS can then receive the request and adjust the frequency of occurrence of the downlink RSs in accordance with the request. In particular, the DL RSs may be for a beam management procedure at the BS.

Furthermore, according to various aspects it is possible that the BS provides reserved resources on the data carrier for the purpose of facilitating the beam management procedure at the UE. In particular, the UE and RRD can use the reserved resources to implement transmission of reference signals, to find suitable beam pairs. The UE can request such reserved resources. For instance, the UE can transmit UL RSs, e.g., sounding RSs (SRSs). Such resources could be reserved on the data carrier and/or an auxiliary carrier.

Still further, according to various examples it is possible to implement a testing procedure that facilitates determining whether a given UE is being served via the RRD or directly reached by the BS. For this purpose, the RRD can be controlled - using a control message - to temporarily, during a testing duration, divert or deactivate reflecting or amplifying incident signals towards the UE and/or towards the BS. Then, it is possible to transmit RSs during the testing duration and determine, based on one or more receive properties - e.g., receive strength -, information indicative of whether or not the UE is being served via the RRD. For instance, a comparison could be made between one or more receive properties of RSs that are transmitted during the testing duration and RSs that are transmitted before after the testing duration. Such testing can then serve as a decision criterion on whether or not the UE requests a reduced frequency of occurrence of DL RSs to be transmitted by the BS.

According to various examples, it would be possible to control the RRD so that the incident signals are reflected into directions at which no further nodes are located, to thereby mitigating interference. For instance, a target output spatial direction could be provided to the RRD. For instance, an omni-directional scattering would be conceivable.

By such and further techniques, the beam management at the BS and/or at the UE can be supported. In particular, it is possible to flexibly react to a change in the situation of the communication system with respect to the RRD. Control-signaling overhead can be reduced. For instance, fewer RSs may be required to be transmitted and/or reduced feedback signaling may be required.

FIG. 1 schematically illustrates a communication system 100. The communication system includes two nodes 101 , 102 that are configured to communicate with each other via a data carrier 111. For instance, the data carrier 111 may have a carrier frequency of not less than 20 GHz or even not less than 40 GHz. THz frequencies are conceivable. It would also be possible to use sub-6GHz frequencies. The data carrier 111 may be via an RRD (not illustrated in FIG. 1 ).

In the example of FIG. 1 , the node 101 is implemented by an access node, more specifically a BS, and the node 102 is implemented by a UE. The BS 101 can be part of a cellular NW (not shown in FIG.1 ) or another communications NW.

As a general rule, the techniques described herein could be used for various types of communication systems, e.g., also for peer-to-peer communication, etc. For the sake of simplicity, however, hereinafter, various techniques will be described in the context of a communication system that is implemented by a BS 101 of a cellular NW and a UE 102.

As illustrated in FIG. 1 , there can be DL communication, as well as uplink (UL) communication. Various examples described herein particularly focus on the DL communication of RSs that are repeatedly transmitted by the BS 101 to the UE 102. However, similar techniques may be applied to, e.g., UL communication of RSs repeatedly transmitted by the UE 102 to the BS 101.

FIG. 2 illustrates details with respect to the BS 101. The BS 101 implements an access node to a communications network, e.g., a 3GPP-specified cellular network. The BS 101 includes control circuitry that is implemented by a processor 1011 and a nonvolatile memory 1015. The processor 1011 can load program code that is stored in the memory 1015. The processor 1011 can then execute the program code. Executing the program code causes the processor to perform techniques as described herein, e.g.: adjusting a frequency of occurrence of DL RSs transmitted to the UE 102; receiving a request to adjust the frequency of occurrence of the DL RSs from the UE 102; reserving resources on the spectrum for beam management procedure at the UE 102, in particular for a scenario where the UE 102 communicates with an RRD; testing whether the UE 102 is served via an RRD; etc.

FIG. 2 also illustrates details with respect to the UE 102. The UE 102 includes control circuitry that is implemented by a processor 1021 and a non-volatile memory 1025. The processor 1021 can load program code that is stored in the memory 1025. The processor can execute the program code. Executing the program code causes the processor to perform techniques as described herein, e.g.: based on a state of a beam management procedure, requesting an adjusted frequency of occurrence of DL RSs and a BS; testing whether the UE 102 is served via an RRD; etc.

FIG. 2 also illustrates details with respect to communication between the BS 101 and the UE 102 on the data carrier 111. The BS 101 includes an interface 1012 that can access and control multiple antennas 1014. Likewise, the UE 102 includes an interface 1022 that can access and control multiple antennas 1024.

While the scenario of FIG. 2 illustrates the antennas 1014 being coupled to the BS 101 , as a general rule, it would be possible to employ transmit-receive points (TRPs) that are spaced apart from the BS.

The interfaces 1012, 1022 can each include one or more TX chains and one or more receiver chains. For instance, such RX chains can include low noise amplifiers, analogue to digital converters, mixers, etc. Analogue and/or digital beamforming would be possible.

Thereby, phase-coherent transmitting and/or receiving (communicating) can be implemented across the multiple antennas 1014, 1024. Thereby, the BS 101 and the UE 102 can selectively transmit on multiple TX beams (beamforming), to thereby direct energy into distinct spatial directions. Different spatial propagation paths can be addressed. By using a TX beam, the direction of the wavefront of signals transmitted by a transmitter of the communication system is controlled. Energy is focused into a respective direction or even multiple directions, by phase-coherent superposition of the individual signals originating from each antenna 1014, 1024. Thereby, the spatial data stream can be directed. The spatial data streams transmitted on multiple beams can be independent, resulting in spatial multiplexing multi-antenna transmission; or dependent on each other, e.g., redundant, resulting in diversity multi-input multi-output (MIMO) transmission.

As a general rule, alternatively or additionally to such TX beams, it is possible to employ receive (RX) beams.

As illustrated in FIG. 2, the UE 102 also includes an auxiliary interface 1082 that is configured to couple with a plurality of antennas 1084. Using the auxiliary interface 1082, the UE 102 can communicate on an auxiliary carrier 199.

As a general rule, at least in some scenarios, it would be possible that for communicating on the auxiliary carrier 199, the UE 102 can re-use the interface 1022 also used to communicate on the data carrier 111 ; in such a scenario it is not required that the UE 102 includes the additional auxiliary interface 1082.

FIG. 3 illustrates aspects with respect to beamforming at the BS 101. The BS 101 can use multiple beams 301 -308 - e.g., TX beams and/or RX beams - to communicate with the UE 102. The UE 102 is served by the beam 308.

In the illustrated example of FIG. 3, the beam width 399 of the beams 301 -308 is comparably large. Wide beam widths are typically used during a stage of the beam management corresponding to an initial beam-pair establishment or beam-pair reestablishment stage. Wide beams may be used in high-mobility cases. Typical RSs used for such stage of the beam management include synchronization signals broadcasted according to a predefined repetitive timing. It is also possible to use CSI- RSs. The beam management at the BS 101 to select the appropriate one of beams 301 -308 can be based on beam-swept DL RSs, cf. TAB. 1A, scenario I.

Above, it has been explained how the BS 101 can perform its beam management to select the beam 308. It is possible that based on further DL RSs - e.g., not transmitted in a beam sweep but rather on a single beam -, the UE 102 can perform its beam management to select beams reciprocal with the beam 308. Thus, the beam management at the UE 102 and at the BS 101 are based on different RSs.

FIG. 4 illustrates aspects with respect to beamforming at the BS 101. The BS 101 - upon identifying the general direction at which the UE 102 is located, corresponding to the beam 308 - can further refine the beam to be used. This corresponds to a beam refinement stage of the beam management. Again, DL RSs transmitted in a beam- swept RS transmission - cf. TAB. 1A, scenario I - can be used. As illustrated in FIG. 4, it is possible to select between multiple comparably narrow beams 311 -316 - e.g., TX beams and/or RX beams - that are all aligned with the wider beam 308. For example, it would be possible to continuously track which one of the narrow beams 311 -316 to use. If this tracking fails, a fallback to the establishment stage is possible.

Typically, during such beam refinement / tracking stage of the beam management, DL CSI-RSs are used. While broadcasted synchronization signals are typically always-on, CSI-RSs can have a periodic, semi-persistent or a periodic time behavior and, therefore, may not always need to be transmitted. They can be transmitted on demand.

FIG. 5 illustrates aspects with respect to beamforming. Here, the BS 101 uses the beam 308 to communicate in a direction at which a RRD 109 is arranged. Various techniques are based on the finding that the beam 308 can be activated comparably statically, because the RRD 109 and the BS 101 have a relatively fixed position. The beam 308 could be predefined. According to various examples, it is possible to reduce a frequency of occurrence of DL RSs required for the beam management at the BS 101 , as explained above in connection with FIG. 3 and FIG. 4.

The RRD 109 can implement multi-antenna operation to reflect or amplify signals towards the UE 102. Details with respect to the RRD 109 are illustrated in connection with FIG. 6.

FIG. 6 illustrates aspects in connection with the RRD 109. The RRD 109 could be implemented by a LIS or a smart repeater. The RRD 109 is configured for multiantenna operation. The RRD 109 includes a phased array of antennas 1094 that impose a configurable phase shift when reflecting incident signals. This defines respective spatial filters that are associated with spatial directions into which the incident signals are reflected. In one example, the antennas 1094 can be passive or semi-passive elements that do not provide any amplification. The RRD 109 thus provides coverage extension by reflection of radio-frequency (RF) signals. Another example includes amplification of RF signals. In any case, a translation to the baseband may not be required. This is different, to, e.g., decode-and-forward repeater or relay functionality. In particular, a latency associated with the operation of the RRD 109 may be significantly smaller than the latency of a decode-an-forward repeater. In particular, the latency introduced by the operation of the RRD 109 may be smaller than a typical symbol duration of symbols - e.g. OFDM symbols - communicated between the nodes.

The RRD 109 includes an antenna interface 1095 and a processor 1091 that can activate respective spatial filters one after another, e.g., in accordance with a reconfiguration timing that defines the dwell time per spatial filter.

Further, there is a communication interface 1092 such that communication on an auxiliary carrier 199 can be established between the RRD 109 and, e.g., the BS 101 and/or the UE 102 (cf. TAB. 1 : scenario A or B). Example implementations of the auxiliary carrier 199 include, e.g., a Wi-Fi protocol or a Bluetooth protocol. A control link with, e.g., the BS 101 and/or the UE 102 can be established on the auxiliary carrier 199.

For instance, RSs for the purpose of a beam management procedure at the RRD 109 may be communicated on the auxiliary carrier 199. For instance, the UE 102 may transmit RSs to the RRD 109. For example, it would be possible to perform angle-of- arrival measurements or other positioning techniques (e.g., path loss, and/or angle-of- departure, etc.) based on such RSs communicated on the auxiliary carrier 199 as part of the beam management procedure. Thereby, the relative positioning of the RRD with respect to the UE 102 can be probed and, accordingly, it is possible to select appropriately aligned TX and/or RX beams at the RRD 109 for communication on the data carrier 111. Such techniques assume that the spatial propagation paths of signals communicated on the auxiliary carrier 199 will not significantly deviate from the spatial propagation paths of signals communicated on the data carrier 111.

As will be appreciated from the above, the auxiliary carrier 199 can be used to assist the beam management procedure at the RRD 109. The processor 1091 can load program code from a non-volatile memory 1093 and execute the program code. Executing the program code causes the processor to perform techniques as described herein, e.g.: supporting a beam management procedure of the UE 102, e.g., by performing angle-of-arrival measurement on RSs transmitted by the UE 102 and/or by transmitting RSs to the UE 102 on the auxiliary carrier 199; receiving, via a control link - e.g., established on the auxiliary carrier 199 - control data, e.g., requesting the RRD to temporarily deactivate itself or reflect/amplify incident signals into a direction misaligned with, e.g., the BS 101 and/or the UE 102; other examples of control data include timing information, configuration information for unit cells, etc.

FIG. 6 is only one example implementation of the RRD 109. Other implementations are conceivable. For example, a meta-material surface not including distinct antenna elements may be used. The meta-material can have a configurable refraction index. To provide re-configurable refraction index, the meta-material may be made of repetitive tunable structures that have extensions smaller than the wavelength of the incident RF signals.

FIG. 7 schematically illustrates aspects with respect to beamforming. The scenario of FIG. 7 generally corresponds to the scenario of FIG. 3. In the scenario of FIG. 7, the UE 102 is served via the RRD 109. In the illustrated example, the RRD 109 is controlled via the control link 199A - e.g., implemented on the auxiliary carrier 199 or a fixed-wire connection - by the BS 101 (cf. TAB. 1 , scenario A). It would likewise be possible that the RRD 109 is controlled by the UE 102 (cf. TAB. 1 , scenario B). The RRD 109 can also be controlled by, both, the BS 101 , as well as the UE 102. Alternatively or additionally, it would also be possible that the RRD 109 is controlled by another entity, e.g., a cloud-based service provider.

In the illustrated example of FIG. 7, the RRD 109 can select between multiple spatial filters that are associated with the input/output spatial directions defined by beams 321 - 328.

From a comparison of FIG. 7 with FIG. 3 or FIG. 4 it follows that even in presence of UE mobility, the BS beam 308 remains static, i.e. , UE mobility is accounted for by the beam management at the RRD 109. Based on this finding, it is possible to reduce a frequency of occurrence of DL RSs used by the BS for the BS beam management. FIG. 7 generally corresponds to a beam establishment stage of the beam management procedure where a beam pair at the RRD 109 and the UE 102 is initially established or re-established. The beams 321 -327 are, accordingly, comparably wide.

FIG. 8 schematically illustrates aspects with respect to beamforming. The scenario of FIG. 8 generally corresponds to the scenario of FIG. 4. In the scenario of FIG. 8, the UE 102 is served via the RRD 109, as already explained above in connection with FIG. 7. In the scenario of FIG. 8, a beam refinement/tracking stage of a beam management procedure is implemented, to select the appropriate spatial filter 331 -336.

Likewise, FIG. 8 corresponds to beam refinement/tracking stage of the beam management procedure at the UE 102 where an appropriate TX beam and/or RX beam corresponding to one of the beams 331 -336 of the associated spatial filter at the RRD 109 is selected at the UE 102.

As a general rule, the beam management at the UE 102 - in presence of the RRD 109, as illustrated in FIGs. 7 and 8 - can be based on DL RSs transmitted by the BS 101 (cf. TAB. 1A, scenario I). In some scenarios, it would be possible that the beam management at the UE 102 in such a scenario is based on RSs transmitted by the RRD 109, e.g., in an auxiliary carrier 199; in this case, it may be possible to reduce the frequency of occurrence of DL RSs transmitted by the BS 101 for the purpose of beam management at the UE 102 (cf. TAB. 1A, scenario II).

With respect to FIG. 7 and FIG. 8, it is illustrated that the BS 101 and the RRD 109 communicate using a broad BS beam 308. As a general rule, it would also be possible to use a beam refinement using a narrower BS beam, e.g., one of the beams 311 -316. This could be, e.g., based on DL RSs transmitted via the RRD 109 to the UE 1021 (cf. TAB. 1A, scenario I) corresponding feedback signaling from the UE 102 to the BS 101 , the feedback signaling being indicative of one or more receive properties of the DL RSs. Once a narrower BS beam 31 1 -316 has been identified, even this narrower BS beam 311 -316 may again remain comparably static; and accordingly, it may not be required that the BS 101 transmits DL RSs used for beam management at the BS 101 at the high frequency of occurrence.

Thus, as explained above, according to various examples, it is possible to adjust the frequency of occurrence of the RSs transmitted by the BS 101 depending on at least one decision criterion. Thereby, resources on the spectrum can be freed up. Further savings of allocation of resources on the spectrum can be achieved by mitigating the need for measurement reports and feedback on one or more receive properties of such RSs where the frequency of occurrence of the RSs as reduced.

According to various examples, the frequency of occurrence of the RSs may be reduced to zero or may be reduced to a small, finite value. For example, there may be a residual intensity/time domain density of RSs transmitted by the BS 101 , e.g., to track the strength of the spatial channel from the BS 101 the UE 102. The strength of the spatial channel may vary, e.g., due to rotational movements of the UE 102.

As a general rule, there may be multiple DL RS transmissions implemented at the BS, cf. TAB. 1A, scenarios l-lll. It is generally possible, that the frequency of occurrence of DL RS associated with different ones of the DL RS transmissions is adjusted differently. For instance, it would be possible that the RS transmission according to TAB. 1 A, scenario I is adjusted so that the frequency of occurrence of the respective RSs is decreased; while the RS transmission according to TAB. 1A, scenario II is adjusted so that the frequency of occurrence of the respective RSs is increased.

Various techniques are based on the finding that, typically, the BS 101 is not in a position to autonomously decide to adjust the frequency of occurrence of the DL RSs. In a first example, this can be true where the BS is not aware of the presence or absence of the RRD, e.g., as in scenario B of TAB. 1. For instance, the BS 101 may not be able to discriminate between the UE 102 and a further UE 103 (cf. FIG. 7), the UE 102 being served via the RRD 109 and the UE 103 not being served via the RRD 109, but both arranged at a spatial sector for which the BS 101 relies on the beam 308. Thus, the BS 101 may not be able to determine autonomously whether the UE 102 may be eligible for reduced frequency of occurrence of RSs. In a second example, this can also be applicable for a scenario according in which the BS is aware that the UE 102 is being served via the RRD (e.g., cf. TAB. 1 : scenario A). The reason is that the UE 102 might still rely on the RSs transmitted by the BS for its beam management.

Accordingly, according to various techniques described herein, the UE 102 can transmit a request to the BS 101 to adjust the frequency of occurrence - i.e., the temporal density - of DL RSs transmitted by the BS 101 the UE 102, e.g., associated with multiple spatial filtering profiles (cf. TAB. 1A, scenario I). Then, the BS can receive that request and accordingly adjust the frequency of occurrence of the DL RSs.

Adjustment of the frequency of occurrence of the DL RSs may be restricted to the DL TX beam at the BS 101 used for communicating with the UE 102 (e.g., beam 308 in FIG. 7 and FIG. 8). i.e., it is possible to selectively adjust the frequency of occurrence of DL RSs for the DL TX beam at the BS 101 used for communicating with the UE 102. For instance, neighboring TX beams at the BS 101 may not be affected by the adjustment of the frequency of occurrence. Thereby, once the UE 102 moves out of coverage of the RRD, it can immediately provide feedback signaling to the BS 101. The BS 101 is thereby made aware that the UE 102 is not being served via the RRD 109 anymore. In an alternative scenario, the frequency of occurrence of the DL RS may be adjusted for all respective DL TX beams of the respective beam-swept RS transmission.

For example,, a scenario can arise in which the UE communicates to the BS 101 that it does not require a large frequency of occurrence of DL RSs from the BS 101 ; then, for some reasons, a need for a higher frequency of occurrence of RSs may re-arise and the UE 102 may request, at the BS 101 , a higher frequency of occurrence of the DL RSs. A potential reason could be that the support of the auxiliary carrier 199 and the beam management procedure at the UE 102 has stopped temporarily or has a limited quality. For instance, a scenario could be applicable where the frequency of the auxiliary carrier 199 is significantly lower than the frequency of the data carrier 111. For instance, the frequency of the data carrier 111 may be above 40 GHz; while the frequency of the auxiliary carrier 199 may be below 6 GHz, e.g., 2.4 GHz. At such comparably low frequencies, diffraction has an impact on the spatial propagation path, possibly resulting in a non-line-of-sight arrangement of the spatial propagation path. This can be different for the higher frequencies above, e.g., 40 GHz of the data carrier. Therefore, the accuracy of the beam management procedure being supported by the auxiliary carrier may be low at times. Thus, based on the quality it may be possible for the UE 102 to judge that DL RSs are required to be transmitted at a comparably higher frequency of occurrence by the BS 101 . Such and further techniques are explained in greater detail in connection with FIG. 9. In particular, FIG. 9 illustrates the UE operation of the UE 102. FIG. 9 is a flowchart of a method according to various examples. For example, the method of FIG. 9 may be executed by a UE, e.g., by the UE 102. For instance, the method of FIG. 9 may be executed by the processor 1021 upon loading program code from the memory 1025 and executing the program code. Optional boxes are illustrated with dashed lines.

At box 7005, it is judged whether an adjustment of the frequency of occurrence of DL referencing signals transmitted by the BS 101 is required or possible. In the affirmative, at box 7010, a request to adjust the frequency of occurrence of the DL RSs is transmitted to the BS 101 . The request can be indicative of a specific DL TX beam. Box 7005 can depend on at least one decision criterion. Some decision criteria are summarized below in TAB. 2.

TAB. 2: Various examples for decision criteria to adjust the frequency of occurrence of DL RSs. It is possible to combine such options as listed in TAB. 2, to form cumulative decision criteria.

As a general rule, the beam management procedure can include multiple stages (cf. TAB. 2, scenario II). Some of these stages are summarized in TAB. 3.

TAB. 3: Various options for stages of the beam management procedure.

As explained above, at box 7010, the request to adjust the frequency of occurrence of the RSs to be transmitted by the BS 101 is transmitted. The information content of such a request can vary according to different implementations. Some examples of the information content of the request are summarized in TAB. 4 below.

TAB. 4: Various options for implementing the request to adjust the frequency of occurrence of DL RSs transmitted by the BS 101 to the UE 102. It is possible to combine such information content as explained in the different options of TAB. 4 with each other. Furthermore, it would be possible that the request includes respective information also for adjustment of the frequency of occurrence of further RSs. Thereby, different adjustment of the frequency of occurrence for, e.g., scenario I and scenario II according to TAB. 1A could be requested, i.e. , the request can pertain to multiple RSs transmissions.

Next, at box 7015, it is possible to receive a confirmation of the adjusted frequency of occurrence. Again, the confirmation can indicate a specific value for the frequency of occurrence, e.g., a timing configuration and/or a timing value (cf. TAB. 4: options I and III). For example, time-frequency resources may be scheduled in a time-frequency resource grid implemented by a modulation scheme on the data carrier 111 , the timefrequency resources being allocated to the DL RSs.

Then, at box 7020, the UE 102 can monitor for the RSs in accordance with the adjusted frequency of occurrence.

Above, a behavior of the UE 102 has been explained. Next, the behavior of the BS 101 will be explained, in connection with FIG. 10.

FIG. 10 is a flowchart of a method according to various examples. The method of FIG. 10 can be executed by an access node of a communications network. For instance, the method of FIG. 10 can be executed by a BS of a cellular communications network, e.g., the BS 101. Specifically, it would be possible that the method of FIG. 10 is executed by the processor 1011 of the BS 101 upon loading program code from the memory 1015 and executing the program code. Optional boxes are labelled with dashed lines.

At box 7105, the BS 101 receives a request to adjust the frequency of occurrence of RSs transmitted to the UE 102 (and optionally one or more further UEs 103). The request is received from the UE 102. Box 7105 is interrelated with box 7010 of FIG. 9. The BS 101 may allow the request or deny the request, box 7110, based on at least one further decision criterion (different from the decision criterion considered at box 7005). For instance, if other UEs (such as the UE 103, cf. FIG. 7) are also served by a respective TX beam (TX beam 308 in the example of FIG. 7) and/or are associated with the same RSs, then the BS 101 may decide to reject the request. The BS 101 may, e.g., deny the request for the beam establishment stage of the beam management procedure at the BS (cf. FIG. 3), but may grant the request for the beam tracking state of the beam management procedure the BS (cf. FIG. 4). Another decision criterion for denying the request would be that the BS is a mobile BS that relatively moves with respect to the RRD 109. Then, the BS may require a beam-swept DL RS transmission for its beam management. Yet another decision criterion for allowing or denying the request would be the availability of the auxiliary carrier 199 also between the BS 101 and the RRD 109.

In case the request is granted, the BS 101 may in some scenarios transmit a confirmation at box 7115. Box 7115 is interrelated with box 7015 of FIG. 9. For instance, the confirmation could be a measurement configuration commanding the UE to monitor for DL RSs at a certain timing and, optionally, provide a respective measurement report to the BS.

Then, at box 7120, the BS adjusts the frequency of occurrence of the DL RSs in accordance with the request of box 7005 and transmits the RSs at the adjusted frequency.

Here, in particular, the frequency of occurrence of the DL RSs can be selectively adjusted for the at least one DL TX beam used for communicating with the UE 102 that has requested the adjusted frequency of occurrence. Where UE-specific RSs - e.g., CSI-RSs - are being used, it is possible to adjust the frequency of occurrence of these UE-specific RSs associated with the requesting UE 102. Other RSs - associated with other UEs - may remain unaffected. In other scenarios, it would be, however, also possible that the frequency of occurrence is adjusted for all TX beams of the beam- swept RS transmission.

Furthermore, it is not required that the frequency of occurrence of all types of DL RSs transmitted to the UE are adjusted. For instance, it would be possible that the frequency of occurrence of a first type of DL RS transmitted to the UE is adjusted, but the frequency of occurrence of a second type of DL RS is not adjusted, or adjusted differently. For instance, it would be possible that in the presence of an RRD and/or depending on a state of the beam management procedure at the UE the frequency of occurrence of the DL RS transmission according to scenario I of TAB. 1A is decreased, the frequency of occurrence of the DL RS transmission according to scenario II of TAB. 1 A is increased, the frequency of occurrence of the DL RS transmission according to scenario III of TAB. 1A is left unaltered. This has the advantage that control signaling overhead on a spectrum can be reduced, at the same time beam management at the UE can be implemented at high speed, and, thirdly, identification of new beam pairs between the BS and the UE - e.g., if the UE moves out of coverage of the RRD - is available.

FIG. 11 is a flowchart of a method according to various examples. The method of FIG. 11 can be executed by a UE, e.g., the UE 102. For instance, the method of FIG. 11 may be executed by the processor 1021 upon loading program code from the memory 1025 and executing the program code.

The method of FIG. 11 illustrates aspects with respect to determining whether or not the UE 102 is served via the RRD 109. For instance, the method of FIG. 11 may be used as part of box 7005 of FIG. 9, i.e. , (cf. TAB. 2, variant V). It is possible to test whether the UE is being served via the RRD and the state of the beam management procedure can depend on said testing.

In particular, at box 7050, it is possible to request reserved resources. The reserved resources can be requested at the BS 101 . The reserved resources can be protected to perform the beam management procedure at the UE 102, to align the beams between the UE 102 the RRD 109. The reserved resources can reside on the data carrier 111 and/or the auxiliary carrier 199.

At box 7055, it is possible to control the RRD to temporarily stop reflecting and/or amplifying (repeating) incident signals towards the UE 102 and/towards the BS 101. Thus, the repeating functionality of the RRD may be temporarily suspended, defining a testing duration. Incident signals may be diverted away from the UE 102 and/or the BS 101. Depending on the particular scenario of TAB. 1 , such controlling may be implemented by through the BS 101 or by the UE 102 having direct access to a control link towards the RRD 109. A cloud server may be contacted.

At box 7060, a configuration of said testing can be communicated between the UE and the BS 101. For example, the configuration of the testing may specify the reserved resources. The configuration may specify the testing duration. The reserved resources can be scheduled during the testing duration. The configuration could include an RX level threshold for RSs that are transmitted to the UE 102 or from the UE 102 during the testing duration. The particular RSs used during the testing duration can be specified. For instance, a relative threshold or some other quantity that can be used to declare whether a received RS is associated with a reflection/amplification from the RRD may be communicated. Such configuration may be transmitted from the UE 102 to the BS 101 or vice versa. An index of the spatial filter deactivated temporarily by the RRD may be signaled. It would also be possible that the RRD is configured to toggle through multiple spatial filters (beamsweep), where at least one of the candidate angles is directed away (or randomly scattered) from the UE. The beamsweep is associated with RS from the BS with a same spatial filtering.

Then, at box 7065, the RSs for testing whether the UE 102 is being served via the RRD 109 are transmitted. The RSs can be, in particular, transmitted during the testing duration and optionally outside - i.e. , before and/or after - the testing duration.

Based on the method of FIG. 11 , it is possible to determine whether the transmitted RSs at box 7065 are associated with a reflection/amplification from the RRD. The UE 102 may be within the coverage of both the BS 101 and the RRD 109. Thus, it can be served via a beam from the BS 101 directly, or via reflection/notifications at the RRD.

Based on the techniques of FIG. 11 , the UE can determine whether it is being served via the RRD 109 by switching off the RRD or controlling the RRD to redirect reflections away from the UE 102. Then, it is possible to schedule the RSs to be transmitted at box 7065 - using one and the same spatial precoding at the BS, i.e., using the same TX beam at the BS 101 - during and outside of the testing duration. If the RSs received during the testing duration exhibit the same receive properties - e.g., received signal power or receive signal quality - as the RSs received outside of the testing duration, then it can be judged that the UE 102 is not served via the RRD 109. On the other hand, if one or more receive properties of the RSs differ significantly - e.g., by a predefined amount then it can be judged that the UE 102 is being served via the RRD 109.

While the above example has been explained for the UE 102 determining whether it is being served via the RRD 109, in other scenarios, the BS 101 can determine whether the UE 102 is being served via the RRD. Here, the BS can configure the UE 102 to transmit uplink RSs e.g., sounding RSs, during and outside of the testing duration at a fixed uplink TX beam. The BS can configure the RRD temporarily deactivate its repeater functionality by not reflecting incident signals are reflecting incident signals away from the BS.

FIG. 12 is a signaling diagram of communication between the BS 101 , the RRD 109, as well as the UE 102.

Initially, an optional testing procedure 5900 is executed. The testing procedure 5900 enables judgement of whether the UE 102 is being served via the RRD 109 or not. The testing procedure 5900 can be executed in isolation of other processes described in FIG. 12 in some examples.

At 4005, the UE 102 transmits, to the BS 101 , a request 5001 for reserved resources. This corresponds to box 7050 of FIG. 11. For instance, the request 5001 may be a higher layer control message, e.g., a Radio Resource Control (RRC) layer control message.

At 4010, the BS 101 provides a configuration of the testing procedure 5900 to the UE 102. For instance, the configuration can be indicative of a testing duration 5905. The reserved resources are scheduled during the testing duration 5905. Details with respect to the configuration have been discussed in FIG. 11 : box 7060.

At 4012, the BS 101 controls the RRD 109 to temporarily, during the testing duration 5905, divert or deactivate reflecting or amplifying incident signals towards the UE 102.

Instead of the BS 101 controlling the RRD 109, it would also be possible that the UE 102 controls the RRD 109 accordingly. For instance, a respective control message may be provided via the control link 199A to the RRD 109. The control message could be indicative of a target output spatial direction into which the incident signals are to be temporarily diverted during the testing duration 5905, to thereby mitigate interference. This temporary diversion can be achieved, e.g., by a beamsweep at the RRD 109.

Then, the BS 101 transmits RSs 5010 at 4015 and at 4020, i.e. , during and optionally outside of the testing duration 5905. Alternatively or additionally to the BS 101 transmitting the RSs 5010, it would be possible that the UE 102 transmits RSs during and optionally outside of the testing duration 5905 to the BS 101 ; in such case, the RRD 109 would be configured to divert or deactivate reflecting or amplifying incident signals towards the BS 101 during the testing duration 5905.

Then, one or more receive properties - e.g., received signal power or receive signal quality or receive amplitude - can be compared for the RSs 5010 received at the UE 102 at 4015 and at 4020. In case of a significant difference, can be judged at the UE 102 is served via the RRD 109.

The BS 101 informs the UE 102 accordingly (not shown in FIG. 12). This can serve as a decision criterion for determining whether to request the adjusted frequency of occurrence of the DL RS (cf. TAB. 3, example IV). As a general rule, other use cases for such additional information regarding whether the UE 102 is being served via the RRD 109 are possible. An example use case would include the management at the BS. For instance, a certain DL RS used for beam management at the BS - for which the BS receives feedback signaling from the UE - could be increased in its frequency of occurrence or otherwise adjusted. Also, based on such information a count of UEs being served via the RRD can be determined which can be helpful, e.g., for load balancing purposes or other configuration tasks.

The UE 102, at 4025, transmits a request for an adjusted frequency of occurrence of DL RSs to be transmitted by the BS 101 (cf. FIG. 9, box 7010).

The BS 101 , at 4030 transmits the DL RSs 5050 at the adjusted reduced frequency of occurrence (cf. FIG. 10, box 7120). A beam-swept transmission is used, on beams 301 -308. The RS 5050 can be the same or different than the RS 5010.

At 4032, the UE 102 provides feedback signaling 5055 to the BS 101 that is indicative of, e.g., received signal strength of the RS 5050 transmitted on the multiple beams 301 -308. Then, the BS 101 can select the appropriate beam 301 -308. FIG. 12 also illustrates the RS 5090 transmitted by the UE 102 at 4035 on the auxiliary carrier 199, e.g., sounding RS. These RSs 5090 are for the management at the RRD 109. In some other scenarios, it would also be possible that the RRD 109 transmits RSs to the UE 102 for beam management at the UE. This is not the case in the illustrated scenario. Rather, beam management at the UE 102 is implemented using DL RS 5080.

FIG. 12 also illustrates a DL RS 5080 transmitted by the BS 101 only on the single beam 308 (cf. FIG. 5; cf. TAB. 1A, scenario II). The UE 102 can implement an RX beam sweep while the DL RS 5080 are repeatedly transmitted by the BS 101. Then, the UE can select the appropriate beam. In some scenarios, it would be possible to adjust the frequency of occurrence of these RSs 5080 alternatively or additionally to adjusting the frequency of occurrence of the RSs 5050. It would be possible that the request 5001 is for both the RSs 5050, as well as the RSs 5080.

FIG. 13 is a flowchart of a method according to various examples. The method of FIG. 13 can be executed by an access node of a communications network. For instance, the method of FIG. 13 can be executed by a BS of a cellular communications network, e.g., the BS 101. Specifically, it would be possible that the method of FIG. 13 is executed by the processor 1011 of the BS 101 upon loading program code from the memory 1015 and executing the program code. The method of FIG. 13 could also be executed by a UE, e.g., the UE 102. For instance, the method of FIG. 13 may be executed by the processor 1021 upon loading program code from the memory 1025 and executing the program code.

FIG. 13 illustrates aspects with respect to a method of requesting reserved resources. A request is transmitted and/received (communicated) at box 7305. The request is from the UE 102 to the BS 101 (where a scheduling functionality resides). The request is for time-frequency resources of a time-frequency resource grid that are blocked for use by other nodes accessing the spectrum so that the UE 102 and the RRD 109 can autonomously communicate RSs in the respective beam management procedure of the UE 102. This can be, e.g., for a beam-establishment stage of the beam management procedure. The reserved resources can be guaranteed by the BS 101 to not experience interference from other UEs, e.g., the UE 103. The BS also guarantees that other wireless collocated devices will not interfere with the reconfigurable device and the UE. For example, the BS may schedule ZP-CSI-RS. The resources could reside on the data carrier 111 and/or the auxiliary carrier 199.

These reserved resources could - alternatively or additionally to establishing an initial beam pair at the RRD 109 and the UE 102 - be used to implement the testing duration 5905 (cf. FIG. 12).

Summarizing, above, signaling from a UE to a BS has been described that indicates that DL RSs are no longer required for the purpose of beam management at the UE. Also, signaling from the UE to the BS has been described that DL RSs are required by the UE for the purpose of beam management at the UE, e.g., beam (re-)establishment, beam refinement I beam tracking. The signaling might come as part of a beam recovery procedure that is triggered, e.g., when an angle-of-arrival estimation procedure on an auxiliary data carrier fails or is temporarily unavailable or when the UE moves out of coverage of the RRD into direct coverage of the BS.

In particular, the UE can request a certain intensity/frequency of occurrence of DL RSs, e.g., a certain number of DL RSs per unit time with the same precoder at the BS, i.e. , the same TX beam at the BS. For periodic DL RSs, the intensity can depend on the requested duration and on the number of requested RSs per duration.

The UE can alternatively or additionally request a certain time behavior of the DL RSs which can be periodic RSs, aperiodic RSs, and/or semi-persistent RSs.

The techniques facilitate a reduced control-signaling overhead. For instance, fewer RSs may be required per time. Feedback signaling regarding one or more receive properties of the RSs - e.g., amplitude and/or phase - may be reduced.

Although the invention has been shown and described with respect to certain preferred examples, equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the appended claims.

For illustration, various scenarios have been described according to which the UE determines, depending on information indicative of whether the UE is being served via the RRD, whether or not to transmit a request for an adjusted frequency of occurrence of RSs to the BS. Such a scenario can be, in particular, helpful where the UE has the knowledge on whether it is being served via the RRD or not. According to various examples, it would also be possible that the BS has direct knowledge on whether a UE is being served via the RRD or not. For instance, this could be the case where the BS maintains a control link to the RRD (cf. TAB. 1 , scenario A). Here, it may be dispensable that the UE provides the request. Furthermore, according to various examples, the at least one decision criterion used by the UE to judge whether it is possible to reduce the frequency of occurrence of DL RSs includes, at least, whether or not the UE is being served via the RRD. But this is not mandatory. In other scenarios, it would be possible that other decision criteria used. For instance, according to various examples, it would be possible that at least one decision criterion includes a state of a beam management procedure at the UE (but it does not depend on whether the UE is being served via the RRD).

Claims

1 . A method of operating a wireless communication device (102) connectable to a communications network, the wireless communication device (102) being configured to communicate with an access node (101 ) of the communications network via a re-configurable repeater device, RRD (109), the RRD (109) being re- configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier (111 ) are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD (109), the method comprising:

- based on at least one decision criterion, transmitting, to the access node (101 ), a request (5001 ) to adjust a frequency of occurrence of downlink reference signals (5050, 5080) transmitted by the access node (101 ) to the wireless communication device (102) wherein the at least one decision criterion comprises information indicating whether or not the wireless communication device (102) is being served via the RRD (109) when communicating between the wireless communication device (102) and the access node (101 ).

2. A method of operating an access node (101 ) of a communications network, the access node (101 ) communicating with a wireless communication device (102) via a re-configurable repeater device, RRD (109), the RRD (109) being re- configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier (111 ) are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD (109), the method comprising:

- receiving, in accordance with at least one decision criterion and from the wireless communication device (102), a request (5001 ) to adjust a frequency of occurrence of downlink reference signals (5050, 5080) transmitted by the access node (101 ) to the wireless communication device (102), and

- adjusting the frequency of occurrence of the downlink reference signals (5050, 5080) in accordance with the request (5001 ), wherein the at least one decision criterion comprises information indicating whether or not the wireless communication device (102) is being served via the RRD (109) when communicating between the wireless communication device (102) and the access node (101 ).

3. The method of CLAIM 2, further comprising:

- adjusting the frequency of occurrence of further downlink reference signals (5050, 5080) transmitted by the access node (101 ) to the wireless communication device differently to said adjusting of the frequency of occurrence of the downlink reference signals (5050, 5080).

4. The method of CLAIM 3, wherein the further downlink reference signals are for a beam management procedure at the wireless communication device for determining one or more beams to be used by the wireless communication device.

5. The method of any one of CLAIMS 2 to 4, wherein the frequency of occurrence is selectively adjusted depending on at least one further decision criterion.

6. The method of CLAIM 5, wherein the at least one further decision criterion comprises a state of a beam management procedure at the access node for determining one or more beams to be used by the access node and/or a mobility level of the access node.

7. The method of any one of any one of the preceding CLAIMS, wherein the downlink reference signals are for a beam management procedure at the access node for determining one or more beams to be used by the access node.

8. The method of any one of the preceding CLAIMS, wherein the at least one decision criterion further comprises a state of a beam management procedure at the wireless communication device for determining one or more beams to be used by the wireless communication device.

9. The method of CLAIM 8, wherein the state of the beam management procedure at the wireless communication device comprises a stage of the beam management procedure at the wireless communication device, the stage of the beam management procedure being selected from a group comprising: initial beam establishment; beam tracking.

10. The method of any one of the preceding CLAIMS, wherein the at least one decision criterion comprises a change level of an orientation of the wireless communication device.

11 . The method of any one of the preceding CLAIMS, wherein the at least one decision criterion comprises an availability of an auxiliary carrier (199) to assist a beam management procedure at the RRD (109) and/or at the wireless communication device, the auxiliary carrier (199) being different than the data carrier (111 ).

12. The method of any one of the preceding CLAIMS, wherein the at least one decision criterion comprises a quality of a beam management procedure at the RRD and/or at the wireless communication device being assisted by an auxiliary carrier (199), the auxiliary carrier (199) being different than the data carrier (111 ).

13. The method of any one of the preceding CLAIMS, further comprising:

- testing whether the wireless communication device (102) is being served via the RRD (109), wherein the at least one decision criterion comprises a result of said testing.

14. The method of CLAIM 13, wherein said testing comprises controlling the RRD (109) to temporarily, during a testing duration (5905), divert or deactivate reflecting or amplifying the incident signals towards the wireless communication device (102) or towards the access node (101 ), wherein the testing further comprises transmitting the downlink reference signals (5050) or further downlink reference signals (5010) towards the RRD (109) during and/or outside of the testing duration (5905).

15. The method of CLAIM 14, further comprising:

- communicating a configuration of said testing between the wireless communication device (102) and the access node (101 ).

16. The method of CLAIM 15, wherein the configuration comprises a receive level threshold for the downlink reference signals (5050, 5080) or the further downlink reference signals (5090) transmitted during the testing duration towards the RRD (109).

17. The method of CLAIM 15 or 16, wherein the configuration is indicative of at least one of the testing duration (5905) or the downlink reference signals (5050, 5080) or the further downlink reference signals (5090).

18. The method of any one of the preceding CLAIMS, wherein the request (5001 ) is indicative of a requested timing value associated with the frequency of occurrence of the downlink reference signals (5050, 5080).

19. The method of any one of the preceding CLAIMS, wherein the request (5001 ) is indicative of a request for at least one of a

CLAIM periodic timing of the downlink reference signals (5050, 5080), an aperiodic timing of the downlink reference signals (5050, 5080), or a semi-persistent timing of the downlink reference signals (5050, 5080).

20. A method, comprising.

- communicating, between a wireless communication device (102) and an access node (101 ) of a communications network, a control message, the control message being indicative of reserved resources for use by the wireless communication device (102) to perform a beam management procedure, the beam management procedure comprising alignment of beams between the wireless communication device (102) and a reconfigurable repeater device via which the access node (101 ) and the wireless communication device (102) communicate.

21. The method of CLAIM 14 and CLAIM 20, wherein the reserved resources are scheduled during the testing duration (5905).

22. A method of operating a re-configurable repeater device, RRD (109), the RRD (109) being re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier (111 ) are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD (109), the method comprising:

- temporarily, during a testing duration (5905), divert or deactivate reflecting or amplifying incident signals towards a wireless communication device (102) or towards an access node (101 ).

23. The method of CLAIM 22, further comprising:

- receiving a control message requesting the RRD to temporarily divert or deactivate said reflecting or amplifying of the incident signals.

24. The method of CLAIM 23, wherein the control message is indicative of a target output spatial direction into which the incident signals are to be temporarily diverted.

25. A wireless communication device (102) connectable to a communications network, the wireless communication device (102) being configured to communicate with an access node (101 ) of the communications network via a re-configurable repeater device, RRD (109), the RRD (109) being re-configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier (111 ) are accepted and with a respective output spatial direction into which the incident signals are reflected or amplified by the RRD (109), the wireless communication device comprising control circuitry configured to: - based on at least one decision criterion, transmit, to the access node (101 ), a request (5001 ) to adjust a frequency of occurrence of downlink reference signals (5050, 5080) transmitted by the access node (101 ) to the wireless communication device (102) wherein the at least one decision criterion comprises information indicating whether or not the wireless communication device (102) is being served via the RRD (109) when communicating between the wireless communication device (102) and the access node (101 ).

26. The wireless communication device of CLAIM 25, wherein the control circuitry is configured to perform the method of any one of CLAIMS 1 to 19.

27. A node (101 , 102) comprising control circuitry configured to:

- communicate, between a wireless communication device (102) and an access node (101 ) of a communications network, a control message, the control message being indicative of reserved resources for use by the wireless communication device (102) to perform a beam management procedure, the beam management procedure comprising alignment of beams between the wireless communication device (102) and a reconfigurable repeater device via which the access node (101 ) and the wireless communication device (102) communicate.

28. The node of CLAIM 27, wherein to control circuitry is configured to perform the method of CLAIM 20 or 21 .

29. A re-configurable repeater device, RRD (109), the RRD (109) being re- configurable to provide multiple spatial filters, each one of the multiple spatial filters being associated with a respective input spatial direction from which incident signals on a data carrier (111 ) are accepted and with a respective output spatial direction into which incident signals are reflected or amplified by the RRD (109), the RRD comprising a control circuitry configured to:

30. The RRD of CLAIM 29, wherein the control circuitry is configured to perform the method of any one of CLAIMS 22 to 24.