Enhanced device-side beam-sweep procedure

Abstract

A method implemented in a user equipment, UE (120) for facilitating a determination of at least one UE beam to be used in relation to at least one transmit-receive point, TRP (115) in a wireless network (110), the method comprising: receiving from the network node a Channel State Information, CSI, report configuration which indicates at least one downlink reference signal, DL-RS, resource; performing an enhanced UE-side beam-sweep procedure, including: performing measurements on the DL-RS resources indicated by the CSI report configuration using one or more panels (126), and evaluating, based on the measurements performed using a single panel and on a single DL-RS resource, at least two UE beams; and selecting at least one of the evaluated UE beams for use in communication with the TRP.

Description

ENHANCED DEVICE-SIDE BEAM-SWEEP PROCEDURETECHNICAL FIELD

[0001] The present disclosure relates to the field of cellular communication between multiantenna transceivers. In particular, it proposes a novel device-side beam-sweep procedure, which can for example be performed by a user equipment (UE). Further disclosed are methods for facilitating a determination of a UE beam to be used by the UE in relation to a transmit-receive point (TRP), which make us of the novel beam-sweep procedure.BACKGROUND

[0002] The fact that current 3GPP NR beam management procedures are relatively time-consuming has been recognized as a problem. One factor that has contributed to this is that UEs which are limited to analog beamforming may need significant time to find a best UE beam, particularly to find a best receive beam. Indeed, because a conventional UE panel that uses analog beamforming is normally restricted to evaluating one UE beam at a time, a conventional beam management procedure will require as many downlink (DL) reference signal (RS) resources as the UE is going to evaluate by means of that panel. During the beam management procedure, accordingly, the network will transmit an identical DL RS for each of these resources, and the UE performs measurements on the DL RS using different candidate (analog) beamforming weights. In the terminology of the present disclosure, a panel (or UE panel, or antenna panel) is a group of related transmit or receive antennas, as described in detail in the applicant's prior disclosure PCT / EP2022 / 076975.

[0003] Recently released UE models are getting more sophisticated, also with respect to their beamforming architectures. This applies particularly to high-end UEs such as customer-premise equipment (CPE) used in fixed wireless access (FWA) and similar applications. For example, preliminary plans to introduce digital UE beamforming in UEs supporting higher frequencies as well, such as millimeter-wave frequencies, have been made public by some vendors. It is possible that at least some more capable UEs will be equipped with narrowband receivers to speed up the evaluation of UE beams. Digital beamforming may alternatively be referred to as baseband-level beamforming as it is carried out mainly by the UE's baseband circuitry; analog beamforming is carried out mainly by the radio-frequency (RF) circuitry.

[0004] Turning to the future sixth-generation 3GPP specifications (6G), there will be introduced new frequency bands between the frequency ranges FR1 and FR2 - that is, between 6 and 24 GHz - so that a number of similar problems will need to be addressed. These frequency bands to be introduced may include carrier frequencies at which some simpler UEs run analog beamforming, whereas more sophisticated UEs might have a narrowband receiver and / or be configured for digital beamforming. The simpler UEs need conventional beam management procedures to be able to determine a suitable UE beam. The most sophisticated UEs can carry out an equivalent evaluation by evaluating a single measurement while varying the applied digital beamforming settings. Intermediate UEs may still need multiple DL-RS resources to measure on, yet significantly fewer than in the fully- fledged beam management procedure outlined initially.

[0005] A further complicating factor is that some high-end expensive 6G-compliant UEs are expected to have advanced beamformers (e.g., fully digital beamformers) while cheaper UEs rely on simpler beamformers (that is, mainly analog beamformers) even for very high frequency bands above 30 GHz.

[0006] It would be an interesting outlook - both for existing 3GPP NR networks and in anticipation of the 6G technology - to control or to limit beam management's contribution to the total system overhead, and more precisely to find a systematic approach by which the network treats the simpler and the more sophisticated UEs differently in this respect.

[0007] To address a related problem, the applicant's prior disclosure WO2020119893A1 describes a UE which reports a beam sweeping property representing the UEs' ability to perform directional reception or transmission in more than one direction simultaneously.SUMMARY

[0008] One objective of the present disclosure is to reap the benefits of sophisticated UEs with partial digital beamforming (e., hybrid beamforming, time-domain digital beamforming) or full digital beamforming, while ensuring backward compatibility with simpler UEs that need conventional beamforming procedures. It would be desirable to establish a novel protocol by which the network interacts selectively with the UEs depending on their capabilities. A further objective is to liberate radio resources on system level by scheduling the UEs with full or partial digital beamforming capabilities determine a best UE beam in less time and / or with a reduced usage of time-frequency resources. A further objective is to propose an enhanced UE-side beam-sweep procedure.

[0009] At least some of these objectives are achieved by the invention as defined by the independent claims. The dependent claims are directed to advantageous embodiments of the invention.

[0010] In a first aspect of the present disclosure, there is provided a method implemented in a user equipment (UE) for facilitating a determination of at least one UE beam to be used in relation to at least one transmit-receive point (TRP) in a wireless network. The method comprises: receiving from the network node a Channel State Information (CSI) report configuration which indicates at least one downlink reference signal (DL-RS) resource; performing an enhanced UE-side beam-sweep procedure; and selecting at least one of the evaluated UE beams for use in communication with the TRP. The enhanced beam-sweep procedure according to said first aspect includes: performing measurements on the DL-RS resources indicated by the DL-RS configuration associated with the CSI report configuration using one or more panels; and evaluating at least two UE beams based on the measurements performed using a single panel and on a single DL-RS resource.

[0011] The novel beam-sweep procedure is enhanced in the sense that it causes the UE to evaluate two or more UE beams based on a single measurement. This is unlike the capabilities of a conventional UE panel with analog beamforming, which is normally restricted to receiving or transmitting on one UE beam per panel at a time. The two or more UE beams may be evaluated simultaneously during the receiving, or they may be evaluated by processing a recorded single measurement sequentially while applying different beamforming settings.

[0012] The single measurement is performed on a single DL-RS resource. The TRP and UE may operate under a telecommunication protocol where a DL-RS resource is defined as a set of time-frequency resources associated with one specified DL beam (one specified TRP beam). It is appreciated that the DL beam can be repeated for multiple DL-RSs to allow the UE to evaluate different receive beamforming settings (different UE beams) and find a suitable beam pair for the downlink. Based on a reciprocity assumption, the same beam pair may be used for uplink communication too.

[0013] A DL-RS resource may last one time-domain symbol or multiple time-domain symbols. In this context, a time-domain symbol may correspond to an orthogonal frequency-division multiplexing (OFDM) symbol, a DFT- spread OFDM symbol (DFT-S-OFDM symbol), or a further type of time-domain symbol to be used in 6G technology. The duration of the DL-RS resource corresponds to the expected time a UE will need in order to evaluate the associated beam. For a DL-RS resource occupying multiple time-domain symbols, therefore, it is not a viable solution to try and evaluate different UE beams in different time-domain symbols within this DL-RS resource, but the enhanced UE-side beam-sweep procedure will normally require the UE to evaluate two or more UE beams based on measurements performed by a single panel and in the same time-domain symbol. This underlines the importance for the UE to have sophisticated beamforming capabilities, such as full or partial digital beamforming capabilities, if it is to perform the enhanced UE-side beam-sweep procedure.

[0014] In a second aspect of the disclosure, there is provided a method implemented in a network node of a wireless network for facilitating a determination of at least one UE beam to be used by a UE in relation to at least one TRP in the wireless network. According to the method, the network node transmits - to a UE with a number NPof simultaneously receiving panels - a CSI report configuration which indicates a number NRof DL-RS resources, such that a number NBof UE beams to be evaluated during an enhanced UE-side beam-sweep procedure is greater than the product of the number of DL-RS resources and number of panels. In other words, NB> NRNP. The network node then transmits on the DL-RS resources indicated by the CSI report configuration. This allows the UE to evaluate the full number NBof UE beams by means of the UE-side beamsweep procedure.

[0015] It is appreciated that the number NPof simultaneously receiving panels excludes such panels which, for some known or unknown reason, the UE will not use during the beam-sweep procedure. Further, the NPpanels are assumed to be associated with baseband circuitry which enables simultaneous receiving; it may exclude some UE hardware designs where one baseband chain is shared by two or more panels.

[0016] A network node which executes the method according to the second aspect makes use of the UE's ability to evaluate at least two UE beams based on measurements performed using a single panel and on a single DLRS resource. This way, the network node will contribute to more economic usage of the available radio resources in the system, which may allow the network node to serve a greater number of connected UEs.

[0017] There is further provided, according to a third and fourth aspect of the present disclosure, a UE and a network node that operate in accordance with the above-described two methods. In general terms, the UE andthe network node share the effects and advantages of these methods, and they can be implemented with a corresponding degree of technical variation.

[0018] This disclosure will further describe a computer program containing instructions for causing a computer, or any of the UE and network node in particular, to carry out the above methods. The computer program may be stored or distributed on a data carrier. As used herein, a "data carrier” may be a transitory data carrier, such as modulated electromagnetic or optical waves, or a non-transitory data carrier. Non-transitory data carriers include volatile and non-volatile memories, such as permanent and non-permanent storage media of magnetic, optical or solid-state type. Still within the scope of "data carrier”, such memories may be fixedly mounted or portable.

[0019] Some embodiments to be described herein make reference to a capability signifying that the UE supports an enhanced UE-side beam-sweep procedure. As explained above, the enhanced UE-side beam-sweep procedure is one where the UE evaluates at least two UE beams based on measurements performed by a single panel and on a single DL-RS resource. This capability may for example indicate how many UE beams the UE is capable of evaluating using a single panel and on a single DL-RS resource. The network node's decision to transmit a CSI report configuration which indicates not more than NRDL-RS resources (in the above-described operational state where the UE is going to use NPsimultaneously receiving panels to evaluate NB> NRNPUE beams) may be conditional on having received said capability from the UE. Similarly, the UE may expect to receive a CSI report configuration with this content only after it has indicated said capability to the network.

[0020] In one embodiment, the capability may include different values for different panels in the UE. For instance, the capability may include two or more values, which pertain to respective panels or panel types of the UE, for at least one indicated parameter of the capability.

[0021] In one embodiment, the capability may include different values for different frequency bands or different frequency-band combinations. The capability may include two or more values, which pertain to respective frequency bands or frequency-band combinations of the UE, for at least one indicated parameter of the capability.

[0022] For the purposes of the present disclosure, a "beam” may technically correspond to a beamforming setting of a receiver or transmitter. Further, a "beam” may be defined in terms of an DL-RS resource. More precisely, the network may enable UE-side measurements by transmitting on a set of DL-RS resources, wherein each DL-RS resource is transmitted on a separate beam. The network may then schedule the UE on one of said beams by referring to one of the transmitted DL-RS resources, e.g., in terms of DL-RS indices or beam identities (beam IDs), which are in a one-to-one relationship with the corresponding beams. When reciprocity holds, the UE may use the same beam for transmission and receipt, which justifies the term "UE beam”.

[0023] In the present disclosure, a "user equipment” may be a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless camera, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer-premise equipment (CPE), a vehicle-mounted wireless terminal device and the like. The terms wireless device and user equipment are used interchangeably.

[0024] A "network node” may be any equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a wireless device and / or with other network nodes or equipment in the wireless network to enable and / or provide wireless access to the wireless device and / or to perform other functions (e.g., administration) in the wireless network. Examples of network nodes include, but are not limited to, access points (APs), base stations (BSs) including radio base stations, evolved NodeBs (eNBs) and NR NodeBs (gNBs). It is understood that one network node may be associated with one TRP or multiple TRPs, wherein each TRP comprises at least one antenna panel and any associated radio and processing units. The special term access point (AP), which is sometimes used to designate antenna panels in dense localized deployment, shall be considered a special case of a TRP.

[0025] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, on which: figure 1 shows a wireless device in the coverage area of one single-TRP base station and one multi-TRP base station; figure 2 illustrates three example beam management procedures; figure 3 illustrates a transmitter which applies different beamforming weights in different frequency bands; figure 4 a perspective view of a UE with four panels; figure 5 is a schematic drawing of a UE with three panels oriented in orthogonal directions to improve coverage, wherein the UE has one baseband chain at its disposal that can be connected to one of the panels at a time; and figure 6 is a sequence diagram illustrating a method of determining a UE beam to be used for communication between a TRP and a UE.DETAILED DESCRIPTION

[0027] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, on which certain embodiments of the invention are shown. These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, theseembodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.System overview

[0028] Figure 1 relates to a first deployment where a wireless device (or UE) 120 is located in the coverage area of one base station 110 with a single TRP 115 (upper portion of figure 1 ), and one base station 110 with two TRPs 115a, 115b (lower portion of figure 1). The base stations 110 are configured as network nodes in a radio access network within a cellular telecommunication system, such as a 3GPP NR system.

[0029] The figure schematically illustrates, in terms of a number of functional units, the components of the wireless device 120 according to an embodiment. Processing circuitry 122 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 124, e.g. in the form of a storage medium 123. The processing circuitry 122 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). Particularly, the processing circuitry 122 is configured to cause the wireless device 120 to perform a set of operations, or steps, as disclosed below with reference to figure 7. For example, the storage medium 123 may store the set of operations, and the processing circuitry 122 may be configured to retrieve the set of operations from the storage medium 123 to cause the wireless device 120 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 122 is arranged to execute the method 600 for facilitating the determination of a beam to be used when the wireless device 120 communicates with the network node 110, to be described with reference to figure 6. The storage medium 123 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0030] The wireless device 120 may further comprise a communications interface 125 for communications with the network nodes 110. As such, the communications interface 125 may comprise one or more transmitters and receivers, comprising analog and digital components. The processing circuitry 122 controls the general operation of the wireless device 120, e.g. by sending data and control signals to the communications interface 125 and the storage medium 123, by receiving data and reports from the communications interface 125, and by retrieving data and instructions from the storage medium 123. Other components, as well as the related functionality, of the wireless device 120 are omitted in order not to obscure the concepts presented herein.

[0031] Figure 1 further illustrates, in terms of a number of functional units, the components of the network nodes 110 according to an embodiment. Each network node 110 comprises a frontend unit 111 and at least one TRP 115. The frontend unit 111 may be co-located with the TRP 115 or located remotely from this. In the frontend unit 111, processing circuitry 112 is provided using any combination of one or more of a suitable CPU, multiprocessor, microcontroller, DSP, etc., capable of executing software instructions stored in a computer program product 114,e.g. in the form of a storage medium 113. The processing circuitry 112 may further be provided as at least one ASIC or FPGA. Particularly, the processing circuitry 112 is configured to cause each network node 110 to perform a set of operations, or steps, as disclosed below with reference to figure 7. For example, the storage medium 113 may store the set of operations, and the processing circuitry 112 may be configured to retrieve the set of operations from the storage medium 113 to cause the wireless device 110 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 112 is arranged to execute the method 600 for determining a beam to be used when the network node 110 communicates with the wireless device 120, to be described with reference to figure 6. The storage medium 113 may also comprise persistent storage, as exemplified above.

[0032] A network node 110 may further comprise a communications interface, including the TRP 115, for communications with the wireless device 120. As such, the communications interface may comprise one or more transmitters and receivers, comprising analogue and digital components. The processing circuitry 112 controls the general operation of the network node 110, e.g. by sending data and control signals to the communications interface (with the TRP 115) and the storage medium 113, by receiving data and reports from the communications interface, and by retrieving data and instructions from the storage medium 113. Other components, as well as the related functionality, of the network nodes 110 are omitted in order not to obscure the concepts presented herein.Use of SRS in 3GPP NR

[0033] In 3GPP NR, the sounding reference signal (SRS) is used for providing channel state information (CSI) to the gNB in the uplink (UL). The use of SRS includes, e.g., determining appropriate transmit beams or receive beams, and / or performing link adaptation. Link adaptation may include setting the transmission rank and the modulation and coding scheme (MGS). The measurements reported for SRS may also be used for selecting DL and UL (MIMO precoding, which may be used for PUSCH and PDSCH transmission, respectively.

[0034] According to 3GPP LTE and NR specifications, the SRS is configured via the RRC layer, wherein parts of the configuration can be updated (for reduced latency) through MAC-CE signaling. The configuration includes, for example, the SRS resource allocation (the time / frequency mapping and the SRS sequence to use) as well as the time-domain behavior (aperiodic, semi-persistent, or periodic). For aperiodic SRS transmission, the RRC configuration does not activate an SRS transmission from the UE but instead a dynamic activation trigger is transmitted from the gNB in the DL, via the DCI in the PDCCH, which instructs the UE to transmit the SRS once. The SRS is to be transmitted at a predetermined point in time.

[0035] When configuring SRS transmissions the gNB uses the information element (IE) SRS-Config to indicate a set of SRS resources and a set of SRS resource sets, where each SRS resource set contains one or more of the SRS resources.

[0036] Each SRS resource set can be configured with a certain usage. The usage expresses what the SRS transmission is intended to be used for; see 3GPP TS 38.214 for further details. In terms of the protocol, the RRC parameter 'usage' is set to one of 'antennaSwitching', ‘codebook', ‘nonCodebook', and 'beamManagement'.

[0037] An SRS resource set that is configured with usage 'antennaSwitching' is used for reciprocity-based DL precoding (i.e., used to sound the channel in the UL so that the gNB can use reciprocity to set a suitable DL precoder). The UE is expected to transmit one SRS port per UE antenna port.

[0038] An SRS resource set that is configured with usage ‘codebook' is used for codebook-based (CB-based) UL transmission. This is to say, the codebook is used to sound the different UE antennas, or antenna ports, and help the gNB to determine / signal a suitable UL precoder, transmission rank, and MCS for a PUSCH transmission. In an SRS resource set, there are up to two SRS resources with the usage ‘codebook'. How SRS ports are mapped to UE antenna ports is, however, up to UE implementation and not known to the gNB.

[0039] An SRS resource set that is configured with usage ‘nonCodebook' is used for NCB-based UL transmission. Specifically, the UE transmits one SRS resource per candidate beam: It is understood that suitable candidate beams are determined by the UE based on, e.g., CSI-RS measurements in the DL; at this point, an assumption of some degree of beam reciprocity may be relied upon. The gNB then measure such SRS resources and determines which UL beam(s) the UE should apply when carrying out the PUSCH transmission. The gNB further indicates to the UE which beams it should apply by designating a subset of said SRS resources. One UL layer will be transmitted per indicated SRS resource. It is noted once more that the UE is free to map SRS ports to UE antenna ports in whatever fashion; this is left up to UE implementation and generally unknown to the gNB.

[0040] An SRS resource set that is configured with usage 'beamManagement' is used to evaluate different UE beams for analog beamforming arrays. This applies mainly to resources in frequency bands above 6 GHz, that is, the FR2 as far as NR is concerned. The UE transmits one SRS resource per analog beam, and the gNB will perform one reference signal received power (RSRP) measurement per transmitted SRS resource and, in this way, will determine a suitable UE beam that is reported to the UE.Multi-beam operation

[0041] Beam management procedures. In the high frequency range (FR2), multiple radio-frequency (RF) beams may be used to transmit and receive signals at a gNB and a UE. For each DL transmit (Tx) beam used by the gNB, there is typically an associated best UE receive (Rx) beam for receiving the signals sent on the DL beam. The gNB DL beam and the associated UE Rx beam form a beam pair. Suitable beam pairs can be identified through a so-called beam management procedure in NR.

[0042] It is possible to identify a DL beam in terms of an associated DL reference signal (RS) transmitted on the same beam, either periodically, semi-persistently, or aperiodically. The DL-RS for this purpose can be a Synchronization Signal (SS) and Physical Broadcast Channel (PBCH) block (SSB) or a Channel State Information RS (CSI-RS). By measuring on all the DL-RSs, the UE can determine and report to the gNB the bestDL beam to use for DL transmissions. The gNB can then transmit a burst of DL-RS in the reported best DL beam to let the UE evaluate candidate UE Rx beams.

[0043] Although not explicitly stated in the NR specification, beam management is in practice divided into three procedures, which are schematically illustrated in figure 2:P1: Purpose is to find an approximate direction for the UE 120 using wide gNB Tx beams 211, 212, 213 from the gNB 110 covering the whole angular sector. The UE 120 can use a single Rx beam 221. - P1 is expected to utilize beams with rather large beamwidths and where the beam reference signals are transmitted periodically and are shared between all UEs of the cell. Typically reference signals used in P1 are periodic CSI-RSs or SSBs. The UE then reports the N best beams to the gNB and, say, their corresponding RSRP values.P2: Purpose is to refine the gNB Tx beam by doing a new beam search around the coarse direction found in P1, namely, by transmitting regular (narrow) Tx beams 214, 215, 216. The UE 120 can use a single Rx beam 222. - P2 is expected to use aperiodic / or semi-persistent CSI-RS transmitted in narrow beams around the coarse direction found in P1.P3: Used for UEs that have analog beamforming to let them find a suitable UE Rx beam. In P3, the UE 120 receives on multiple beams 223, 224, 225 while the gNB 110 transmits on a constant beam 217, which is preferably a regular (narrow) beam. In the P3 procedure, aperiodic CSI-RSs transmitted in one narrow gNB beam may be used. - P3 is expected to use aperiodic or semi-persistent CSI-RSs repeatedly transmitted in one narrow gNB beam. One alternative way is to let the UE determine a suitable UE RX beam based on the periodic SSB transmission. Since each SSB consists of four OFDM symbols, a maximum of four UE RX beams can be evaluated during each SSB burst transmission. One benefit with using SSB instead of CSI-RS is that no extra overhead of CSI-RS transmission is needed.

[0044] As explained initially, the present disclosure addresses the problem that beam management procedures of the P3 type are relatively time-consuming and contribute noticeably to the CSI-RS overhead on system level.

[0045] Beam management framework in 3GPP NR. By way of technical background, the existing beam management framework according to 3GPP NR Releases 15 / 16 and Release 17 will be briefly summarized. The summary will refer to the concept of quasi co-location (QCL) and the related information element Transmission Configuration Indicator (TCI).

[0046] In NR, several signals can be transmitted from different antenna ports of a same base station. These signals can have the same large-scale properties such as Doppler shift / spread, average delay spread, or average delay. These antenna ports are then said to be quasi co-located (QCL).

[0047] If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g. Doppler spread), the UE can estimate that parameter based on one of the antenna ports and apply that estimate for receiving signal on the other antenna port.

[0048] For example, there may be a QCL relation between a CSI-RS for tracking RS (TRS) and the PDSCH DMRS. When UE receives the PDSCH DMRS it can use the measurements already made on the TRS to assist the DMRS reception.

[0049] Information about what assumptions can be made regarding QCL is signaled to the UE from the network. In NR, four types of QCL relations between a transmitted source RS and transmitted target reference signal (RS) were defined:- Type A: {Doppler shift, Doppler spread, average delay, delay spread}- Type B: {Doppler shift, Doppler spread}- Type C: {average delay, Doppler shift}- Type D: {Spatial Rx parameter}

[0050] QCL Type D was introduced to facilitate beam management with analog beamforming and is known as spatial QCL. There is currently no strict definition of spatial QCL, but the understanding is that if two transmitted antenna ports are spatially QCL, the UE can use the same Rx beam to receive them. This is helpful for a UE that uses analog beamforming to receive signals, since the UE needs to adjust its RX beam in some direction prior to receiving a certain signal. If the UE knows that the signal is spatially QCL with some other signal it has received earlier, then it can safely use the same RX beam to receive also this signal.

[0051] In NR, the spatial QCL relation for a DL or UL signal / channel can be indicated to the UE by using a so- called beam indication. The beam indication is used to help the UE find a suitable Rx beam for DL reception, and / or a suitable Tx beam for UL transmission. In NR, the beam indication for DL is conveyed to the UE by indicating a transmission configuration indicator (TCI) state to the UE, while in UL the "beam indication” can be conveyed by indicating a DL-RS or UL-RS as spatial relation in NR Releases 15 / 16 or by indicating a TCI state in the unified TCI state framework introduced in NR Release 17.

[0052] Beam management with unified TCI state framework. In NR, downlink beam management is performed by conveying spatial QCL (‘Type D') assumptions to the UE in the form of TCI states.

[0053] The NR Relelase-15 and Relelase-16 beam management framework allows great flexibility for the network to instruct the UE to receive signals from different spatial directions in DL, through at the cost of considerable signaling overhead and sometimes slow beam switching. These limitations are particularly noticeable and costly when moving UEs are considered. One example is that beam updating using DCI is only available for PDSCH. To update the beam for other reference signals and channels, MAC-CE and / or RRC signaling is required, which clearly adds extra overhead and latency.

[0054] Furthermore, in majority of cases, the network transmits to and receive from a UE in the same direction for both data and control. Hence, using a separate framework (TCI state respective spatial relations) for different channels and signals tends to complicate the implementations.

[0055] In Release 17, a unified TCI state-based beam indication framework was introduced to simplify beam management in the FR2 range, in which a common beam represented by a TCI state may be activated / indicated to a UE and the common beam is applicable for multiple channels / signals such as PDCCH and PDSCH. The common beam framework is sometimes referred to as unified TCI state framework. A TCI state configured under the newly introduced Rel-17 framework will henceforth be referred to as a unified TCI state.

[0056] The new framework can be RRC-configured in one out two modes of operation, i.e., "Joint DL / UL TCI” or "Separate DL / UL TCI”. For "Joint DL / UL TCI”, one common Joint TCI state is used for both DL and UL signals / channels. For "Separate DL / UL TCI”, one common DL-only TCI state is used for DL channels / signals and one common UL-only TCI state is used for UL signals / channels.

[0057] A unified TCI state for separate DL / UL or Joint DL / UL comprises identifiers of two QCL source reference signals as shown below, where the first RS acts as a QCL source RS for one of the QCL types typeA, typeB and typeC, while the second RS is a QCL source RS for QCL typeD. A QCL source may be understood to be a signal on which measurements are performed and which has a QCL relation to other, non-measured signals. The second RS is used to indicate a spatial beam or filter associated with the unified TCI state. An example of ASN.1 code for configuring separate UL / DL or Joint DL / UL TCI state is shown in Table 1.

[0058] The common TCI state ID can be updated in a similar way as the TCI state ID is update for PDSCH in Release 15 / 16, i.e. with one of two alternatives:- Two-stage: RRC signaling is used to configure a number of TCI states in PDSCH-config, and MAC-CE is used to activate a single TCI state; this single TCI state will be applied.- Three-stage: RRC signaling is used to configure a number TCI state in PDSCH-config, MAC-CE is used to activate up to 8 TCI states, and a 3-bit TCI state bitfield (consisting of up to 8 codepoints) in DCI is used to indicate one of the activated TCI states; the indicated TCI state will be applied.

[0059] For "Joint DL / UL TCI” operation, maximum one Joint TCI state can be activated per TCI codepoint. One schematic example of how this may look is illustrated in figure 5, which is an example of activated TCI states and their mapping to TCI field codepoints for "Joint DL / UL TCI”. If the indicated TCI codepoint is "0”, the UE should apply "Joint TCI state 7” as common QCL source for both DL and UL signals / channels.

[0060] For "Separate DL / UL TCI” operation, up to two TCI states can be activated per TCI codepoint, one for DL signals / channels (DL-only TCI state) and one for UL signals / channels (UL-only TCI state). One schematic example of how this may look is illustrated in figure 6, in a similar format as figure 5. In case the TCI codepoint is "0”, the UE should apply "DL-only TCI state 3” as common QCL source for DL signals / channels, and not update the QCL source for UL signals channel. In case the TCI codepoint is "7”, the UE should apply "UL-only TCI state 57” as QCL source for UL signals / channels, and not update the QCL source for DL signals / channel. In case the TCI codepoint is "3”, the UE should apply "DL-only TCI state 9” as QCL source for DL signals / channels and apply "UL-only TCI state 1” as QCL source for UL signals / channels.

[0061] The existing DCI formats 1_1 and 1_2 in NR are reused (like in the Release-15 / 16 beam management framework) for beam indication, both with and without DL assignment. For DCI formats 1_1 and 1_2 with DL assignment, ACK / NACK of the PDSCH can be used as indication of successful reception of beam indication. For DCI formats 1_1 and 1_2 without DL assignment, a new ACK / NACK mechanism analogous to that for semi- persistent scheduling (SPS) PDSCH release with both type-1 and type-2 HARQ-ACK codebook is used, where upon a successful reception of the beam indication DCI, the UE reports an ACK.

[0062] For DCI-based beam indication, the first slot to apply the indicated TCI state is at least Y symbols after the last symbol of the acknowledgment of the joint or separate DL / UL beam indication. The Y symbols are configured by the gNB based on UE capability, which is also reported in units of symbols.UE beamforminq architecture

[0063] For UEs, the signals can arrive from and emanate into all different directions, which makes it is beneficial to have an antenna implementation at the UE which has the possibility to generate omni-directional-like coverage in addition to the high gain narrow beams. One way to increase the omni-directional coverage at a UE is to install multiple panels, and point (orient) these panels into different directions, which typically is the case for commercial UEs. Reference is made to the applicant's prior disclosure PCT / EP2022 / 076975. A panel may be implemented asmultiple antenna elements per polarization which are arranged in a linear or planar uniform array. However, in order to reduce the cost and energy consumption, some of these UEs can only transmit from one UE panel - or possibly two UE panels - at each point in time.

[0064] Figure 4 illustrates one example of a realistic UE 120 with two baseband chains (one per polarization) 122 which are used to switch between four different dual-polarized panels 126. Each panel 126 is operable to transmit beams in directions typically corresponding to a half plane into the main transmit direction of the panel. More precisely, the antennas in one panel 126 may be oriented parallel to each other into a common direction. Oftentimes though not necessarily, the antennas in one panel 126 are physically close, e.g., the mutual distances of the antennas in one panel 126 are smaller than the distance to an antenna in any other panel. Further, the antennas in one panel 126 may be fed with an RF signal at a common input point, which can be connected and disconnected to the baseband chain 122 collectively.

[0065] Figure 5 shows a wireless device 120 with three panels 126 oriented in orthogonal directions to improve spherical coverage. The wireless device has two baseband chains 122 at its disposal that can be connected to one of the panels 126 at a time. This ability is illustrated by an analog switch in figure 5. Further, the panels 126 differ from each other with respect to maximum number of TX / RX chains, and number of antenna elements. In the drawing, the slash-like symbol inside a panel 126 refers to an antenna element with a first polarization, and the backslash-like symbol refers to an antenna element with a second polarization different from the first polarization.

[0066] With reference to a similar UE structure, it is described in the presentation- Qualcomm Technologies, Breaking the Wireless Barriers to Mobilize 5G NR mmWave, May 2019, downloaded from https: / / www.qualcomm.com / content / dam / qcomm-martech / dm-assets / documents / breaking_the_wireless_baniers_to_mobilize_5g_nr_mmwave.pdf how antenna switching can be used to switch between three UE panel modules.Enhanced UE-side beam-sweep procedure

[0067] In line with the objectives discussed initially, and particularly to control the contribution of beam management procedures to the total overhead, the inventors have developed the UE beam determination method 600 to be described next.

[0068] Reference is made to figure 6, which is a sequence diagram illustrating a method 600 of determining one or more UE beams to be used for communication between a UE 120 (or wireless device) and at least one network node 110 in a wireless network. The method 600 will be described here in an example 3GPP NR context, where the network node 110 acts as a gNB. From the UE's 120 point of view, figure 6 provides a method 600 for facilitating the determination of one or more UE beams to be used by the UE 120 for uplink or downlink communication with a TRP, which may coincide with the network node 110. From the network node's 110perspective, figure 6 provides a method 600 for determining one or more UE beams to be used by the UE 120 for communication with a TRP 115, which may coincide with the network node 120. The network node 110 may additionally determine one or more beams for its own use in said communication. The UE 120 is assumed to be capable of at least partially digital beamforming (or baseband-level beamforming), including various forms of constrained digital beamforming, such as time-domain digital beamforming or frequency-domain digital beamforming. Such forms of digital beamforming may be constrained in the sense that they are available only in a subrange which is significantly smaller than the carrier bandwidth. The distinction between digital and analog beamforming can be understood by comparing figures 9 and 10 in the applicant's above-referenced disclosure WO2020119893A1.

[0069] In an optional first step 610, the UE 120 indicates to the network node 110 a capability signifying that it supports an enhanced UE-side beam-sweep procedure, that is, a procedure where the UE evaluates at least two UE beams based on the measurements performed using a single panel and on a single DL-RS resource. The capability can for example be indicated by RRC signaling, such as within a UECapabilitylnformation message (see 3GPP TS 38.331). The method 600 may in principle be performed without the step 610, for example, if an applicable future standard specifies that a compliant UE 120 shall support at least a number N of instances of UE beam evaluation per UE panel and DL-RS resource, wherein N is 2, 3, 4 or higher.

[0070] In some embodiments, the "enhanced UE-side beam-sweep procedure capability” (which may carry a different name) includes one or more of the following:1 . how many UE beams the UE is capable of evaluating using a single panel and on a single DL-RS resource;2. support of using a narrowband receiver;3. a maximum bandwidth of the narrowband receiver;4. a maximum number of time-domain symbols (e.g., OFDM symbols, DFT-S-OFDM symbols) per slot that the narrowband receiver is capable of processing;5. a start frequency and end frequency of the narrowband receiver;6. whether the narrowband receiver is capable of dynamic frequency-band adaptation;7. support of using a fully digital receiver (or fully frequency-selective digital receiver);8. support of using a time-domain digital receiver (or time-domain digital beamformer), i.e., a digital receiver which can simultaneously apply separate digital beamforming settings in different sub-ranges of its total operational bandwidth;9. a maximum number of simultaneous UE beams that the time-domain digital receiver is capable of evaluating using a single panel;10. a frequency-band granularity per UE beam of the time-domain digital receiver;11. a total number of UE beams.These parameters may be specified in future versions of 3GPP TS 38.306.

[0071] With reference to item 1, the UE may for example be capable of evaluating 2, 3, 4, 8 or 16 beams per panel 126. If UE uses two panels 126 simultaneously, it can normally evaluate the sum the respective numbers of beams. For example, if two panels identified as panel_1 and panel_2 allow simultaneous evaluation of 4 and 2 UE beams, respectively, the combination of these panels allows simultaneous evaluation of 6 UE beams.

[0072] With reference to item 2, a narrowband receiver may for example be understood to be a receiver with a maximum bandwidth of at most 20 MHz (i.e., the receiver is not configured for simultaneous reception over a larger bandwidth than 20 MHz). In a further example, the narrowband receiver is a receiver with a maximum bandwidth of at most 20% of a carrier bandwidth of the wireless network; it is recalled that the current maximum carrier bandwidth in 3GPP NR is 100 MHz.

[0073] With reference to item 3, it is noted that the maximum bandwidth can be expressed in terms of frequency, or as a number of subcarriers or a number of resource blocks.

[0074] With respect to item 6, dynamic frequency-band adaptation refers to the capability of shifting the bandwidth supported by the narrowband receiver within the carrier bandwidth. For example, a UE which operates at a carrier bandwidth of 100 MHz, has a 20-MHz narrowband receiver at its disposal and is capable of dynamic frequency-band adaptation may be able to apply the narrowband receiver in at least two different sub-ranges, such as for example 0-20 MHz, 20-40 MHz, 40-60 MHz, 60-80 MHz and 80-100 MHz. Possibly the sub-ranges may be overlapping, such as 0-20 MHz and 10-30 MHz.

[0075] With reference to item 10, the frequency-band granularity refers to how densely, with respect to frequency, independent values can be assigned to the beamforming weights, such as 50 or 100 subcarriers, or 5 or 20 resource blocks of 12 subcarriers each. For example, if the frequency-band granularity is 50 MHz and the carrier beamwidth is 100 MHz, then the UE can receive on a first UE beam in the range 0-50 MHz and a second UE beam in 50-100 MHz. Related to this, figure 3 illustrates an advanced network-side transmitter which applies different beamforming weights in different frequency bands, so as to transmit to a large number of FWA subscribers.

[0076] With reference to item 11, the total number of UE beams may be a quantity of relevance to the network when determining how many DL-RS resources the UE needs to be allocated in order to evaluate the beams. For example, if the UE is capable of forming a total number of 8 unique beams by means of beamforming and if it can evaluate 2 beams simultaneously, the network may decide to allocate 4 DL-RS resources to the UE.

[0077] In some embodiments, one or more of the above parameters of the capability are indicated independently for different UE panels (i.e., there two or more values pertaining to respective panels of the UE). In some embodiments, one or more of the above parameters of the capability are indicated independently for different UE panel types. In some embodiments, one or more of the above parameters of the capability are indicatedindependently for different groups of UE panels. In some embodiments, one or more of the above parameters of the capability are indicated independently for different frequency band or frequency-band combinations. In some embodiments, further, one or more of the above parameters of the capability are indicated by a common value for all panels of the UE.

[0078] In some embodiments, at least one of the values assigned to the above parameters is associated with a metaparameter which signifies the scope of applicability of the value. The metaparameter can be defined to have any of the values in one of the following sets:- identities of individual panels (e.g. panel_1, panel_2, panel_3, .... panel_ / VP), identities of groups of panels, and optionally all panels;- identities of individual panels, all panels;- identities of individual panels, identities of individual panel types, and optionally all panels;- identities of individual frequency bands, the full frequency range;- identities of individual frequency-band combinations, the full frequency range.Alternatively, the metaparameter can be defined to have any of the values in a set formed by combining two or more of the above sets. Referring to the parameters above, the capability may include the value assignment according to Table 2.This signifies that a first panel with identifier "1” can evaluate 2 simultaneous UE beams, and a second panel with identifier "2” can evaluate 4 simultaneous UE beams. Further all panels of the UE 110 are associated with a narrowband receiver.

[0079] The method 600 may include an optional step 612, where the network node 110 transmits - and the UE 120 receives - a CSI report configuration indicating at least one DL-RS resource. The CSI configuration may be conveyed using semistatic signaling, such as RRC signaling. In some embodiments, the CSI report configuration indicates the DL-RS resource(s) through the intermediary of a DL-RS configuration; for example, in 3GPP NR, a CSI-ReportConfig may activate a separately configured CSI-ResourceConfig by referring to its ID. In otherembodiments, the CSI report configuration indicates the DL-RS resource(s) explicitly. The DL-RS resources may correspond to Channel State Information RS (CSI-RS) resources or to SSB or an equivalent DL-RS type yet to be specified in 6G. In some embodiments, the DL-RS resources may form a number of DL-RS resource sets. The DL-RS resources may for example be expressed in terms of time-frequency resources or beam identities (beam IDs). As noted initially, a DL-RS resource may last one time-domain symbol or multiple time-domain symbols.

[0080] In a situation where the UE 120 has NPsimultaneously receiving panels 126 and is going to evaluate NBUE beams during the beam-sweep procedure and where the CSI report configuration indicates no more than NRDL-RS resources, a CSI report configuration that mandates the performing of an enhanced beam-sweep procedure can be recognized by the fact that NB> NRNP. The network node 110 may be configured to transmit 612 a CSI report configuration with this number NRof DL-RS resources on the condition that the UE 110 indicated 610 that it supports the enhanced UE-side beam-sweep procedure. In terms of item 1, the condition may be that the UE 110 has indicated a value of at least 2 for at least one of its panels.

[0081] In some embodiments, the network node 110 transmits 612 the configuration in response to being explicitly or implicitly requested by the wireless device 120 to do so.

[0082] If the network node 110 has received, in step 610, a UE capability which contains specifics about the wireless device 120, the network node 110 may in some embodiments adapt at least one characteristic of the CSI report - notably at least one UE-dependent characteristic - to these specifics. These are a few envisioned examples:- The network node 110 is configured to establish the number NBof UE beams to be evaluated (item 11) and the number NPof panels to be used by the UE during the enhanced UE-side beam-sweep procedure; the network node 110 then determines the number NRof DL-RS resources, while optionally considering how many UE beams the UE is capable of evaluating using a single panel 126 (item 1).- The network node 110 is configured to transmit a CSI report configuration which indicates CSI-RS resources having a scheduled bandwidth contained in the maximum bandwidth of the narrowband receiver (item 3).- The network node 110 is configured to transmit a CSI report configuration which indicates CSI-RS resources having a scheduled bandwidth contained between the start frequency and end frequency of the narrowband receiver (item 5).- The network node 110 is configured to transmit a CSI report configuration that indicates a number of CSI-RS resources equal to a ratio of the total number of UE beams and the maximum number of simultaneous UE beams that the time-domain digital receiver is capable of evaluating using a single panel (items 1, 11).

[0083] In embodiments of the method 600 where no explicit configuration is transmitted (i.e., where step 612 is absent), the wireless device 120 may be implicitly configured to perform the enhanced UE-side beam-sweep procedure by a pre-agreed (standardized) specification.

[0084] In a further optional step 614 of the method 600, the network node 110 transmits - or causes a TRP 115 to transmit- a measurement trigger for the UE 120 to perform measurements on one or more of the configured DL-RS resources. The measurement trigger is received by the UE 120. The measurement trigger can be conveyed in Downlink Control Information (DCI), in a MAC-layer control element (MAC-CE), by RRC signaling, or by another suitable signaling vehicle. Relevant 3GPP specifications for NR include 38.212 and 38.321 . Optionally, the measurement trigger includes an indication of a beam type to be used for receiving the DL-RS resources. The beam type is preferably a beam type selected from a plurality of beam types with different beam widths, e.g., by indicating an index of that beam type from a pre-agreed list. The indication of the beam type may be in part implicit, e.g. there may be a pre-agreed rule that the absence of a beam-type data element in the measurement trigger indicates that the UE 120 shall receive a default beam type.

[0085] Triggering is required mainly if the DL-RS resources have an aperiodic time-domain behavior. It is advantageous, for example, if the UE 120 has different beamforming architectures for different UE panels or different UE panel types and if moreover the UE has indicated a certain UE panel or UE panel type associated with a previous gNB beam report (similarly to what was introduced in NR Release 17, where the UE can indicate a UE panel type for each reported beam in a gNB beam report). In this situation, the network node 110 may trigger an enhanced UE-side beam sweep based on the UE capability signaling associated with the indicated UE panel or UE panel type. In one possible scenario, the UE has indicated - in a previous gNB beam report - that the best DL-RS (corresponding to the best gNB beam) is associated with UE panel_1 and has furthermore indicated - during UE capability signaling (step 610) - that UE panel_1 is equipped with a digital narrowband receiver. In this scenario, the gNB can trigger an enhanced UE-side beam sweep procedure consisting of a single DL-RS resource; the scheduled bandwidth of the indicated DL-RS resources should match the bandwidth of the narrowband receiver of UE panel_1.

[0086] Subsequently, in a step 616, the network node 110 transmits on the DL-RS resources indicated by the CSI report configuration. (In alternative language, which is closer to the terminology of 3GPP TS 38.214, the gNB 110 transmits said DL-RS resources.) Optionally, the network node 110 performs the transmission on the DL-RS resources through the intermediary of one or more TRPs 115, i.e., it causes one or more TRPs 115 to perform the transmission. In particular, the network node 110 may transmit on the DL-RS resources using at least one TRP 115 that was not used for transmitting the DL-RS configuration and / or the measurement trigger.

[0087] The UE 120 is expected to perform, in a step 618, measurements on these DL-RS resources. If multiple panels 126 are used, at least some of the measurements may be simultaneous or partially overlapping in time. It is recalled that simultaneity of measurements is not essential for the UE's ability to evaluate more than one UE beam based on measurements performed on a single DL-RS resource; indeed, the evaluation of multiple UEbeams may also be achieved by recording a single measurement and processing it while applying different (receiver) beamforming settings and comparing the outcomes. The processing while applying different beamforming settings may be carried out as a sequence of procedures or as a number of parallel, timeoverlapping procedures. The measurements may be CSI-RS measurements in accordance with a 3GPP NR specification or in accordance with a forthcoming 6G specification; it is understood that the 6G specification may specify the CSI-RS measurements identically or similarly to 3GPP NR, or in a novel way.

[0088] In a next step 620, on the basis of the measurements in step 618, the UE 120 may select a most suitable UE beam or UE beams. The UE beam may be identified by the DL-RS resource; it may be the one on which the DL-RS was received by the UE 120 with highest signal energy or highest signal to interference and noise ratio (SI NR).

[0089] The UE 120 may indicate its selection of a UE beam to the the network node 110, optionally through the intermediary of a TRP 115. The UE 120 may indicate its selection by transmitting a CSI report according to the 3GPP NR specifications and by transmitting it on the same channels and uplink resources. In future 3GPP releases, including future 6G technology, the indicated selection of a UE beam may have the format of a new type of beam report (new type of CSI report) that is transmitted either on newly defined uplink channels or on legacy uplink channels (e.g., PUCCH, PUSCH) in this technology.

[0090] The selected UE beam or beams are then used by the network node 110 and UE 120, in a step 622, for communication. The communication, which could proceed through the intermediary of a TRP 115, may include downlink transmission of data and signaling, in which a selected UE beam corresponds to a setting of the receiver beamformer in the UE 110. Alternatively or additionally, the communication may include an uplink transmission of data and signaling, in which the selected UE beam corresponds to a setting of the transmitter beamformer in the UE 110. In some embodiments, a smaller bandwidth - e.g., a bandwidth where digital beamforming is available, such as a bandwidth supported by a narrowband receiver - is used for the UE beam evaluation, wherein the communication in step 622 is performed on the full bandwidth. These embodiments, in other words, include performing the enhanced UE-side beam-sweep procedure (step 618) at a first bandwidth and performing the UL or DL communication (step 622) at a second bandwidth, which is greater than the first bandwidth. In particular, some embodiments may include performing the enhanced UE-side beam-sweep procedure (step 618) in a first frequency range and performing the UL or DL communication (step 622) in a second frequency range, such that the first frequency range is contained in the second frequency range.

[0091] The aspects of the present disclosure have mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims

CLAIMS1. A method (600) implemented in a user equipment, UE (120) for facilitating a determination of at least one UE beam to be used in relation to at least one transmit-receive point, TRP (115) in a wireless network (110), the method comprising: receiving (612) from the network node a Channel State Information, CSI, report configuration which indicates at least one downlink reference signal, DL-RS, resource; performing an enhanced UE-side beam-sweep procedure (618), including: performing measurements on the DL-RS resources indicated by the CSI report configuration using one or more panels (126); and evaluating, based on the measurements performed using a single panel and on a single DL-RS resource, at least two UE beams; and selecting (620) at least one of the evaluated UE beams for use in communication with the TRP.

2. The method of claim 1 , further comprising: receiving (614) from the network a measurement trigger, wherein the enhanced UE-side beam-sweep procedure is initiated in response to receiving the measurement trigger.

3. The method of claim 1 or 2, further comprising: indicating (610), to a network node of the wireless network, a capability signifying that the UE supports an enhanced UE-side beam-sweep procedure.

4. A method (600) implemented in a network node of a wireless network (110) for facilitating a determination of at least one user equipment, UE, beam to be used by a UE (120) in relation to at least one transmit-receive point, TRP (115) in the wireless network, the method comprising: to a UE with a number NPof simultaneously receiving panels (126), transmitting (612) a Channel State Information, CSI, report configuration which indicates a number NRof downlink reference signal, DL-RS, resources, such that a number NBof UE beams to be evaluated during an enhanced UE-side beam-sweep procedure is greater than the product of the number of DL-RS resources and number of panels, NB> NPNP; and transmitting (616) on the DL-RS resources indicated by the CSI report configuration.

5. The method of claim 4, further comprising: establishing the number NBof UE beams to be evaluated and the number NPof panels to be used by the UE during the enhanced UE-side beam-sweep procedure.

6. The method of claim 4 or 5, further comprising:receiving (610) a capability signifying that the UE supports an enhanced UE-side beam-sweep procedure, wherein the transmitting (612) of the CSI report configuration which indicates NRDL-RS resources is conditional on having received said capability.

7. The method of any of claim 6, further comprising: adapting at least one characteristic of the CSI report configuration in accordance with the received capability.

8. The method of any of the preceding claims, wherein the CSI report configuration indicates the DL-RS resource(s) through the intermediary of a DL-RS configuration.

9. The method of any of the preceding claims, wherein the CSI report configuration indicates CSI-RS resources.

10. The method of claim 3 or 6, wherein the capability indicates how many UE beams the UE is capable of evaluating using a single panel and on a single DL-RS resource.11 . The method of claim 3 or 6, wherein the capability indicates one or more of: a) support of using a narrowband receiver with a maximum bandwidth of at most 20 MHz and / or at most 20% of a carrier bandwidth of the wireless network; b) a maximum bandwidth of the narrowband receiver; c) a maximum number of time-domain symbols per slot that the narrowband receiver is capable of processing; d) a start and end frequency of the narrowband receiver; e) whether the narrowband receiver is capable of dynamic frequency-band adaptation.

12. The method of claim 11, wherein the CSI report configuration indicates CSI-RS resources having a scheduled bandwidth contained in the maximum bandwidth of the narrowband receiver.

13. The method of claim 3 or 6, wherein the capability indicates: a) support of using a fully digital receiver.

14. The method of claim 3 or 6, wherein the capability indicates one or more of: a) support of using a time-domain digital receiver; b) a maximum number of simultaneous UE beams that the time-domain digital receiver is capable of evaluating using a single panel; c) a frequency-band granularity of the time-domain digital receiver; d) a total number of UE beams.

15. The method of claim 14, wherein the CSI report configuration indicates a number of CSI-RS resources equal to a ratio of the total number of UE beams and the maximum number of simultaneous UE beams that the time-domain digital receiver is capable of evaluating using a single panel.

16. The method of any of claims 10 to 15, wherein, for at least one indicated parameter of the capability, there are two or more values pertaining to respective panels or panel types of the UE.

17. The method of any of claims 10 to 16, wherein, for at least one indicated parameter of the capability, there is a single value pertaining to two or more panels of the UE, in particular, pertaining to all panels of the UE.

18. The method of any of claims 10 to 17, wherein, for at least one indicated parameter of the capability, there are two or more values pertaining to respective frequency bands or respective frequency-band combinations.

19. The method of any of claims 10 to 18, wherein at least one of the values assigned to the parameters of the capability is associated with a metaparameter which signifies its scope of applicability.

20. The method of any of the preceding claims, further comprising: performing communication (622) between the UE and the network node.

21. A user equipment, UE (120) for facilitating a determination of at least one UE beam to be used in relation to at least one transmit-receive point, TRP (115) in a wireless network (110), the UE comprising processing circuitry (122) configured: to receive from the network node a Channel State Information, CSI, report configuration which indicates at least one downlink reference signal, DL-RS, resource; to perform an enhanced UE-side beam-sweep procedure (618), including: performing measurements on the DL-RS resources indicated by the DL-RS configuration associated with the CSI report configuration using one or more panels (126); and evaluating, based on the measurements performed using a single panel and on a single DL-RS resource, at least two UE beams; and to select at least one of the evaluated UE beams for use in communication with the TRP.

22. A network node of a wireless network (110) for facilitating a determination of at least one user equipment, UE, beam to be used by a UE (120) in relation to at least one transmit-receive point, TRP (115) in the wireless network, the network node comprising processing circuitry (112) configured: to transmit, to a UE with a number NPof simultaneously receiving panels (126), a Channel State Information, CSI, report configuration which indicates a number NRof downlink reference signal, DL-RS, resources, such that a number NBof UE beams to be evaluated during an enhanced UE-side beam-sweep procedure is greater than the product of the number of DL-RS resources and number of panels, NB> NBNP; and to transmit on the DL-RS resources indicated by the CSI report configuration.

23. A computer program (124) comprising instructions which, when run on processing circuitry (122) of a UE (120), cause the UE to perform the method (600) of any of claims 1 to 3 and 8 to 20.

24. A computer program (114) comprising instructions which, when run on processing circuitry (112) of a network node, cause the network node to perform the method (600) of any of claims 4 to 20.

25. A computer program product comprising the computer program (114, 124) of claim 23 or 24 and a computer-readable storage medium on which the computer program is stored.

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