Uplink reference signal-based beam sweep

Abstract

There is provided techniques for performing an UL reference signal-based UE-sided beam sweep procedure. A method is performed by a UE. The method comprises sending a first message to a network node serving the UE indicating a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The method comprises receiving a second message from the network node comprising an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The method comprises transmitting the UL reference signal resources in different beams with the specified gap period between each beam switch.

Description

[0001] UPLINK REFERENCE SIGNAL-BASED BEAM SWEEP

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to a method, a user equipment, a computer program, and a computer program product for performing an uplink reference signal-based user equipment-sided beam sweep procedure. Embodiments presented herein further relate to a method, a network node, a computer program, and a computer program product for configuring the user equipment for the uplink reference signal-based user equipment-sided beam sweep procedure.

[0004] BACKGROUND

[0005] Terahertz (THz) band communication (i.e., communication in the frequency range 0.1-10 THz) might support ultra-broadband connectivity for sixth-generation (6G) telecommunication systems and beyond.

[0006] One impairment at such frequencies is increased phase noise. Large sub-carrier spacings (e.g., larger than in fourth-generation (4G) and fifth-generation (5G) telecommunication systems might be needed to combat to combat the phase noise. As a result, the symbol length used in for THz communication might be much smaller than in Frequency Range 1 (FR1) and Frequency Range 2 (FR2). For example, the sub-carrier spacing envisioned for sub-THz communication (0.1-0.3 THz) is of 960 kHz or 1920 kHz which will result in symbol times of around 1 pis, which is much smaller than the symbol length of 8.33 pis resulting for sub-carrier spacing of 120 kHz in FR2 bands. Furthermore, much smaller symbol lengths than 1 pis can take place beyond sub-THz bands, e.g., in THz frequencies bands from 300 GHz to 10 THz.

[0007] In such high frequency ranges, multiple radio-frequency (RF) beams, or just beams for short, may be used to transmit and receive signals at the network side (represented by a network node, such as a gNB) and the user side (represented by a user equipment (UE), such as a smartphone or the like.

[0008] Some UEs might have analog beamformers with poor beam correspondence, which implies that downlink / uplink (DL / UL) reciprocity cannot be used to determine the beams for these beamformers. For such UEs, the UE beam used for the UL cannot be derived from beam management procedures based on reference signals transmitted in the DL. This can be handled by means of UL beam. One difference between DL beam management and UL beam management is that UL beam management utilizes uplink reference signals, such as sounding reference signals (SRS), instead of DL reference signals. Two UL beam management procedures, denoted U2 and U3, are currently supported for communication over the New Radio (NR) air interface. In short, the U2 procedure is performed by the UE transmitting a burst of SRS resources in one and the same UE transmit beam and letting the network node, evaluate different network node receive beams. The U3 procedure lets the UE evaluate UE transmit beam by the UE transmitting different SRS resources in different UE transmit beams. Reference is here made to Fig. 1 which schematically illustrates a communication system 100 comprising a UE 110 and a network node 120. The UE 110 is performing an UL reference signal-based UE-sided beam sweep 140 in a set of B beams 130a: 130B. In this way, the UE is enabled to transmit different SRS resources in the B beams.

[0009] UL beam management can also be useful even if UEs have beam correspondence, as illustrated by the following two examples.

[0010] As a first example, an "UL only” network node is equipped with UL capability but with none or very limited downlink capability. In this case, since the "UL only” network node is not capable of transmitting DL reference signals, the beam pair link between a UE and an "UL only” node has to be based on UL beam management procedures.

[0011] As a second example, dense distributed multiple-input multiple-output (D-MIMO) communication systems comprise many different network nodes in terms of access points (AP) or transmission points (TRPs) that are distributed in a small geographical area. Each AP, or TRP, might be configured for beamforming. In case DL beam management is used to determine a which AP, or TRP, to serve a given UE, and further to determine which beam should be used by the AP, or TRP, for communication with the given UE, significant amount of reference signal overhead is need. The selection of AP, or TRP, and the corresponding beam selection might therefore be based on UL reference signal transmission in an effort to reduce the overhead. These UL reference signals could then be used to determine a which AP, or TRP, to serve the given UE, and further to determine which beam should be used by the AP, or TRP, for communication with the given UE.

[0012] In general terms, for UEs, signals can arrive from, and be emanated to, many different directions. Hence can be beneficial to have an antenna array implementation at the UE which has the possibility to generate omni- directional-like beams in addition to high gain narrow beams. One way to increase the omni-directional coverage at a UE is to install multiple antenna panels (each comprising one or more antenna arrays), and orient the antenna panels in distinct directions. However, in order to reduce the cost and energy consumption, transmission and reception is only possible from one (or two) antenna panel(s) at each time instance. Fig. 2 illustrates one example of a UE 200 comprising three antenna panels (generally comprising P antenna panels) 220a:220P. Each antenna panel 220a:220P comprises dual-polarized antenna elements 230. All antenna panels 220a:220P are, via a switch 240, connectible to one baseband chain 210 per polarization.

[0013] A UE can signal support for UL beam management procedures by indicating the capability "uplinkBeamManagement” during UE capability signaling. As part of this capability the UE can indicate the maximum number of supported SRS resources per SRS resource set with usage beam management with the parameter "maxNumberSRS-ResourcePerSet-BM”. This could be used as an indication of the number of narrow beams the UE can generate per antenna panel. However, only one single value can be reported. Hence there is no possibility to indicate different number of supported beams per antenna panels, or different number of beams for different beam widths. Due to the short symbol times at (sub-)THz frequencies, it will be challenging for some, or all, UEs to switch between different (analog) beams and / or between different antenna panels from one symbol to another during a UL reference signal-based beam sweep, as for example performed during the aforementioned U3 procedure. In addition, in case the UE turns off / on power amplifiers (PAs) at the RF front-ends when switching from one (analog) beam to another, the UL reference signal-based beam sweep procedure becomes even more challenging because of the transients resulting from switching the PAs on and off.

[0014] In addition, since the symbol time is very short in THz communications, the link budget for the reference signals used during a U3 procedures might become unreliably low, which could deteriorate the beam sweep procedure.

[0015] Hence, there is still a need for improved UL reference signal-based beam sweep procedures.

[0016] SUMMARY

[0017] An object of embodiments herein is to address the above issues and provide an UL reference signal-based beam sweep procedure that does not suffer from the above issues, or where the above issues at least are mitigated or reduced.

[0018] Due to the short symbol times at (sub-)THz frequencies, the network node might schedule UL reference signals in a way where there is not enough time for the UE to switch between different beams. The UE might therefore not be able to meet the demands as set by the network node for the UE to perform the U3 procedure. The U3 procedure might thereby fail, or possibly give suboptimal result, due to the UE being out of time sync with the network node. A particular object is therefore to provide an UL reference signal-based beam sweep procedure that allows the UE to perform the required switching between antenna panels and / or beams from one symbol to another during the UL reference signal-based beam sweep.

[0019] A particular object is to provide an UL reference signal-based beam sweep procedure that is feasible for THz- band communication.

[0020] According to a first aspect there is presented a method for performing an UL reference signal-based UE-sided beam sweep procedure. The method is performed by a UE. The method comprises sending a first message to a network node serving the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The method comprises receiving a second message from the network node. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The method comprises transmitting, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources in different beams with the specified gap period between each beam switch. According to a second aspect there is presented a UE for performing an UL reference signal-based UE-sided beam sweep procedure. The UE comprises processing circuitry. The processing circuitry is configured to cause the UE to send a first message to a network node serving the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The processing circuitry is configured to cause the UE to receive a second message from the network node. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The processing circuitry is configured to cause the UE to transmit, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources in different beams with the specified gap period between each beam switch.

[0021] According to a third aspect there is presented a UE for performing an UL reference signal-based UE-sided beam sweep procedure. The UE comprises a send module configured to send a first message to a network node serving the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE- sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The UE comprises a receive module configured to receive a second message from the network node. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The UE comprises a transmit module configured to transmit, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources in different beams with the specified gap period between each beam switch.

[0022] According to a fourth aspect there is presented a computer program for performing an UL reference signal-based UE-sided beam sweep procedure 140. The computer program comprises computer code which, when run on processing circuitry of a UE, causes the UE to perform actions. One action comprises the UE to send a first message to a network node serving the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. One action comprises the UE to receive a second message from the network node. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. One action comprises the UE to transmit, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources in different beams with the specified gap period between each beam switch. According to a fifth aspect there is presented a method for configuring a UE for an UL reference signal-based UE- sided beam sweep procedure. The method is performed by a network node. The method comprises receiving a first message from the UE. The first message indicates a capability of the UE to perform the UL reference signalbased UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The method comprises sending a second message to the UE. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The method comprises receiving, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources from the UE with the specified gap period between each of the UL reference signal resources.

[0023] According to a sixth aspect there is presented a network node for configuring a UE for an UL reference signalbased UE-sided beam sweep procedure. The network node comprises processing circuitry. The processing circuitry is configured to cause the network node to receive a first message from the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The processing circuitry is configured to cause the network node to send a second message to the UE. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The processing circuitry is configured to cause the network node to receive, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources from the UE with the specified gap period between each of the UL reference signal resources.

[0024] According to a seventh aspect there is presented a network node for configuring a UE for an UL reference signalbased UE-sided beam sweep procedure. The network node comprises a first receive module configured to receive a first message from the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. The network node comprises a send module configured to send a second message to the UE. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. The network node comprises a second receive module configured to receive, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources from the UE with the specified gap period between each of the UL reference signal resources. According to an eighth aspect there is presented a computer program for configuring a UE for an UL reference signal-based UE-sided beam sweep procedure. The computer program comprises computer code which, when run on processing circuitry of a network node, causes the network node to perform actions. One action comprises the network node to receive a first message from the UE. The first message indicates a capability of the UE to perform the UL reference signal-based UE-sided beam sweep procedure. The capability specifies at least a required gap period for the UE to switch beams during the beam sweep procedure. One action comprises the network node to send a second message to the UE. The second message comprises an UL reference signal configuration for a set of UL reference signal resources to be transmitted in the beams. The UL reference signal configuration comprises a specified gap period between two consecutive UL reference signal resources. The specified gap period is at least as long as the required gap period. One action comprises the network node to receive, during the UL reference signal-based UE-sided beam sweep procedure, the UL reference signal resources from the UE with the specified gap period between each of the UL reference signal resources.

[0025] According to a ninth aspect there is presented a computer program product comprising a computer program according to at least one of the fourth aspect and the eighth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

[0026] Advantageously, the proposed beam sweep procedure does not suffer from the above issues.

[0027] Advantageously, the proposed beam sweep procedure allows the UE to perform the required switching between antenna panels and / or beams from one symbol to another during an UL reference signal-based beam sweep.

[0028] Advantageously, these aspects enable UL reference signal-based beam sweep procedures to be introduced for THz-band communication.

[0029] Advantageously, by means of the proposed beam sweep procedure, larger beam selection accuracy can be obtained than if having a gap period shorter than the required gap period.

[0030] In turn, due to improved beam selection accuracy, the beam sweep overheads can be reduced (e.g., requiring less repeated transmissions) to maintain a certain beam selection accuracy.

[0031] In turn, due to mitigation of, e.g., PA, transients affect during beam switching, the proposed beam sweep procedure yields low (in-band and) out-of-band interference during the beam sweeping procedure.

[0032] Advantageously, these aspects enable the UL reference signal resource allocation to be matched to the available maximum transmit power, yielding a good tradeoff between UL link budget and reference signal overhead and latency. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0033] 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, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, 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.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0036] Fig. 1 is a schematic diagram illustrating an uplink reference signal-based user equipment-sided beam sweep according to examples;

[0037] Fig. 2 is a schematic block diagram of a user equipment according to examples;

[0038] Figs. 3 and 4 are flowcharts of methods according to embodiments;

[0039] Fig. 5 is a schematic illustration of a UE performing two examples of a UE reference signal-based UE-sided beam sweep procedure according to embodiments;

[0040] Fig. 6 is a schematic illustration of a specified gap period of two OFDM symbols during a UE reference signalbased UE-sided beam sweep procedure according to an embodiment;

[0041] Fig. 7 is a signaling diagram of a method according to an embodiment;

[0042] Fig. 8 is a schematic diagram showing structural units of a user equipment according to an embodiment;

[0043] Fig. 9 is a schematic diagram showing functional modules of a user equipment according to an embodiment;

[0044] Fig. 10 is a schematic diagram showing structural units of a network node according to an embodiment;

[0045] Fig. 11 is a schematic diagram showing functional modules of a network node according to an embodiment; and

[0046] Fig. 12 shows one example of a computer program product comprising computer readable means according to an embodiment. DETAILED DESCRIPTION

[0047] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0048] As disclosed above, there is still a need for improved UL reference signal-based beam sweep procedures.

[0049] The embodiments disclosed herein in particular relate to techniques for performing an UL reference signal-based UE-sided beam sweep procedure 140 and for configuring the UE 110 for the UL reference signal-based UE-sided beam sweep procedure 140. In order to obtain such techniques, there is provided a UE 110, a method performed by the UE 110, a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the UE 110, causes the UE 110 to perform the method. In order to obtain such techniques, there is further provided a network node 120, a method performed by the network node 120, and a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the network node 120, causes the network node 120 to perform the method.

[0050] Reference is now made to Fig. 3 illustrating a method for performing a UE reference signal-based UE-sided beam sweep procedure 140 as performed by the UE 110 according to an embodiment.

[0051] S102: The UE 110 sends a first message to a network node 120 serving the UE 110. The first message indicates a capability of the UE 110 to perform the UE reference signal-based UE-sided beam sweep procedure 140. The capability specifies at least a required gap period for the UE 110 to switch beams 130a: 130B during the beam sweep procedure 140. This enables gap periods to be defined for UL reference signals such as SRSs with usage 'beamManagement'. This enables the UE 110 to provide a capability report for UL reference signal beam sweeping where the UE can indicate, for example, a preferred, or at least a minimum required, gap period for switching beams within one and the same antenna panel and / or between different antenna panels during a U3 procedure. A gap period generally denotes a period associated with non-transmissions between subsequent UL transmissions of reference signals during the UE reference signal-based UE-sided beam sweep procedure 140. In this respect, the required gap period might be related to a certain performance level for the UE 110 to perform the UE reference signal-based UE-sided beam sweep procedure 140. The preferred gap period can be regarded as the required gap period plus some tolerance, as given by some tolerance level for the given performance level. The required gap period can be regarded as the bare minimum gap period based on hardware constraints, etc. in the UE 110 for performing the beam switch. S104: The UE 110 receives a second message from the network node 120. The second message comprises a UE reference signal configuration for a set of UE reference signal resources to be transmitted in the beams 130a: 130B. The UE reference signal configuration comprises a specified gap period between two consecutive UE reference signal resources. The specified gap period is at least as long as the required gap period.

[0052] S106: The UE 110 transmits, during the UE reference signal-based UE-sided beam sweep procedure 140, the UE reference signal resources in different beams 130a: 130B with the specified gap period between each beam switch.

[0053] Embodiments relating to further details of performing a UE reference signal-based UE-sided beam sweep procedure 140 as performed by the UE 110 will now be disclosed.

[0054] The herein disclosed UE reference signal-based UE-sided beam sweep procedure 140 can be performed for different types of carrier frequencies. Specifically, it is feasible for communication at frequencies above 30 GHz. In particular, in some embodiments, the UE reference signal-based UE-sided beam sweep procedure 140 is performed in a frequency band above 30 GHz. In some non-limiting examples, the UE reference signal-based UE-sided beam sweep procedure 140 is performed in a frequency band from 40 GHz to 70 GHz, or from 50 GHz to 150 GHz, or from 250 GHz to 350 GHz.

[0055] There can be different switches between the different beams 130a: 130B in step S106. For example, the beams 130a: 130B might be switched within one and the same antenna panel, or from one antenna panel to the next. That is, in some embodiments, the beam switch is performed between beams 130a: 130B generated by one same antenna panel 220a:220P at the UE 110 or between beams 130a: 130B generated by different antenna panels 220a:220P at the UE 110.

[0056] A first minimum gap period can be indicated when switching between beams 130a: 130B within one antenna panel and a second minimum gap period can be indicated when switching between beams 130a: 130B belonging to different antenna panels. That is, in some embodiments, the capability specifies at least one first required gap period for the UE 110 to switch between beams 130a: 130B generated by one same antenna panel 220a:220P at the UE 110 and / or at least one second required gap period for the UE 110 to switch between beams 130a: 130B generated by two different antenna panels 220a:220P at the UE 110. This can be advantageous in case the switching from one antenna panel to the next introduces some additional time delay.

[0057] In some examples, the gap period introduced when switching between beams of the same antenna panel, or between beams of different antenna panels, is the same. Expressed differently, there is only one gap period used during the UE beam sweep, regardless of whether the UE is switching between beams generated at the same antenna panel, or between beams generated by different antenna panels. In another example, the gap period introduced when switching between beams generated by one and the same panel is different compared to the gap period introduced when switching between beams generated by different panels. For example, there may be one gap period used when switching between two beams generated by one and the same antenna panel, and another gap period used when switching between two beams that not generated by one and the same panel (and thus two gap periods in total). In some examples, there is one and the same gap period for every time the UE switches beams generated at the same antenna panel, and P, possibly different, gap periods (where P is the number of panels) for the UE when switching across different antenna panels. One common minimum gap-period can thus be indicated for all antenna panels, or different minimum gap periods can be indicated for different antenna panels. Therefore, in some aspects, different minimum gap periods are indicated for different antenna panels. In particular, in some embodiments, the beams 130a: 130B are generated by P number of antenna panels 220a:220P at the UE 110, and the capability specifies one required gap period for each pair of antenna panels 220a:220P. In one non-limiting example, one gap period is reported per antenna panel, meaning that P gap periods are reported. In one example, one gap period is reported per antenna panel type, meaning that either P gap periods are reported or fewer than P gap periods are reported. In one non-limiting example, one gap period is reported per antenna panel pair, meaning that (P - 1)1 gap periods are reported; e.g., if there are P = 4 antenna panels in total, and these 4 antenna panels are denoted P1 , P2, P3, and P4, then one gap period can be reported between each of the (P - 1)! = (4-1)! = 3! = 3'2U = 6 antenna panel pairs: (P1, P2), (P1, P3), (P1, P4), (P2, P3), (P2, P4), and (P3, P4), i.e., six gap periods in total.

[0058] Likewise, one common minimum gap-period can be in indicated for all beams, or different minimum gap periods can be indicated for different beams. Therefore, in some aspects, different minimum gap periods indicated for different beams 130a: 130B. In particular, in some embodiments, B number of beams 130a: 130B are generated per antenna panel 220a:220P at the UE 110, and the capability specifies one required gap period for each pair of beams 130a: 130B. In summary, if there are B beams per antenna panel, and P antenna panels in total, there might in total be P-B gap periods. In general, the number of required gap periods (and the number of specified gap periods) may be between 1 and P-B gap periods.

[0059] There can be different ways for the UE 110 to specify the gap period. In some non-limiting examples, required gap period is specified in terms of any of: milliseconds, microseconds, number of time-domain symbols (e.g., orthogonal frequency-division multiplexing (OFDM) symbols). In some examples, the one or more gap periods consists of a certain number of time-domain symbols. In another example, the one or more gap periods between different SRS resources consists of at least a certain number of time-domain symbols.

[0060] Also further parameters might be specified in the capability. In some embodiments, the capability in the first message further pertains to at least one of: sub-carrier spacings supported by the UE 110 for performing the UE reference signal-based UE-sided beam sweep procedure 140, requested number of beams 130a: 130B at the UE 110 to be evaluated during the UE reference signal-based UE-sided beam sweep procedure 140, maximum supported number of simultaneously active antennas 230, power amplifiers, and / or radio-frequency front-ends per beam 130a: 130B. The minimum gap period can be reported for all sub-carrier spacing, or per sub-carrier spacing. That is, in some embodiments, one required gap period is specified per each sub-carrier spacing. The number of time-domain symbols might then depend on the sub-carrier spacing of the associated UE reference signals. In particular, in some embodiments, the number of time-domain symbols further depends on sub-carrier spacings used during the UE reference signal-based UE-sided beam sweep procedure 140. That is, the time duration of the one or more gap periods between transmission of the different UL reference signals might thus depend on the subcarrier spacing of the associated UL reference signal resources.

[0061] In some embodiments, the number of symbols per each of the UE reference signal resources depends on maximum supported number of simultaneously active antennas 230, power amplifiers, and / or radio-frequency front-ends per beam 130a: 130B at the UE 110. For example, the network node might configure the UE with UL reference signal resources according to the indicated number of simultaneously used antennas, RF front-ends, or PAs per beam, or maximum supported number of simultaneously used UE antennas, RF front-ends, or PAs. For example, beams that are to be generated with a given number, say X, of antennas, or RF front-ends, or PAs, which is the double compared to other beams which are only created with X / 2 number of antennas, RF frontends, or PAs, might be allocated half of the time domain resources for sounding compared to the resources for sounding allocated to beams which are only generated with X / 2 number of antennas, RF front-ends, or PAs. This will be further illustrated below with reference to Fig. 5.

[0062] Reference is now made to Fig. 4 illustrating a method for configuring a UE 110 for a UE reference signal-based UE-sided beam sweep procedure 140 as performed by the network node 120 according to an embodiment.

[0063] S202: The network node 120 receives a first message from the UE 110. The first message indicates a capability of the UE 110 to perform the UE reference signal-based UE-sided beam sweep procedure 140. The capability specifies at least a required gap period for the UE 110 to switch beams 130a: 130B during the beam sweep procedure 140.

[0064] S204: The network node 120 sending S204 a second message to the UE 110. The second message comprises a UE reference signal configuration for a set of UE reference signal resources to be transmitted in the beams 130a: 130B. The UE reference signal configuration comprises a specified gap period between two consecutive UE reference signal resources. The specified gap period is at least as long as the required gap period.

[0065] S206: The network node 120 receives, during the UE reference signal-based UE-sided beam sweep procedure 140, the UE reference signal resources from the UE 110 with the specified gap period between each of the UE reference signal resources.

[0066] Embodiments relating to further details of configuring a UE 110 for a UE reference signal-based UE-sided beam sweep procedure 140 as performed by the network node 120 will now be disclosed. As disclosed above, in some embodiments, the UE reference signal-based UE-sided beam sweep procedure 140 is performed in a frequency band above 30 GHz. As further disclosed above, in some non-limiting examples, the UE reference signal-based UE-sided beam sweep procedure 140 is performed in a frequency band from 40 GHz to 70 GHz, or from 50 GHz to 150 GHz, or from 250 GHz to 350 GHz.

[0067] As disclosed above, a first minimum gap period can be indicated when switching between beams 130a: 130B within one antenna panel and a second minimum gap period can be indicated when switching between beams 130a: 130B belonging to different antenna panels. That is, in some embodiments, the capability specifies at least one first required gap period for the UE 110 to switch between beams 130a: 130B generated by one same antenna panel 220a:220P at the UE 110 and / or at least one second required gap period for the UE 110 to switch between beams 130a: 130B generated by two different antenna panels 220a:220P at the UE 110.

[0068] As disclosed above, there could be different minimum gap periods indicated for different antenna panels. That is, in some embodiments, the capability specifies one required gap period for each pair of antenna panels 220a:220P at the UE 110.

[0069] As disclosed above, there could be different minimum gap periods indicated for different UE beams 130a: 130B. That is, in some embodiments, the capability specifies one required gap period for each pair of beams 130a: 130B per antenna panel 220a:220P at the UE 110.

[0070] As disclosed above, in some embodiments, the required gap period is specified in terms of any of: milliseconds, microseconds, number of time-domain symbols.

[0071] As disclosed above, in some embodiments, the capability in the first message further pertains to at least one of: sub-carrier spacings supported by the UE 110 for performing the UE reference signal-based UE-sided beam sweep procedure 140, requested number of beams 130a: 130B at the UE 110 to be evaluated during the UE reference signal-based UE-sided beam sweep procedure 140, maximum supported number of simultaneously active antennas 230, power amplifiers, and / or radio-frequency front-ends per beam 130a: 130B. As disclosed above, in some embodiments, the number of symbols per each of the UE reference signal resources depends on maximum supported number of simultaneously active antennas 230, power amplifiers, and / or radio-frequency front-ends per beam 130a: 130B at the UE 110.

[0072] In Fig. 5 is schematically illustrated a UE 110 performing two examples (a) and (b) of a UE reference signalbased UE-sided beam sweep procedure. The UE 110 comprises a digital baseband 210 operatively connected to an antenna panel 220 (with four antenna elements), via RF circuitry 250 comprising four RF components, such as RF front-ends and / or PAs. The RF circuitry 250 is powered by a power supply 240. In the first example, the UE is using one RF front-end, or PA. In the second example, the UE is using two RF front-ends, or PAs. This difference impacts how many symbols is used for the UL reference signal resources. In the first example, the single-antenna beams B1 , B2, B3, B4 with lowest transmit power are allocated four OFDM symbols per UL reference signal resource. In the second example, two-antenna beams, B1 , B2, are allocated two OFDM symbols each per UL reference signal resource. In both examples the received energy in the UL is the same, i.e., same UL reference signal link budget is supported.

[0073] In Fig. 6 schematically illustrates an example of a specified gap period of two OFDM symbols during a UE reference signal-based UE-sided beam sweep procedure in four beams B1 , B2, B3, B4. The UE first transmits a first UL reference signal resource in a first beam B1 , then, after a gap period of two OFDM symbols, transmits a second UL reference signal resource in a second beam B2, then, after another gap period of two OFDM symbols, transmits a third UL reference signal resource in a third beam B3, and then, after yet another gap period of two OFDM symbols, transmits a fourth UL reference signal resource in a fourth beam B4. In this example, the UE has thus indicated a minimum required gap period of two time-domain symbols to allow for proper beam switching.

[0074] One particular embodiment for a UE reference signal-based UE-sided beam sweep procedure 140 as performed by the UE 110 and the network node 120 based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signaling diagram of Fig. 7.

[0075] In this embodiment, the network node 120 is represented by a gNB. Further, in this embodiment, the UE reference signal-based UE-sided beam sweep procedure is a U3 procedure for THz frequencies using SRS as UL reference signals.

[0076] S301 : The UE indicates, e.g., during UE capability signaling, support for an SRS based UE-sided beam sweep procedure for frequencies above 30 GHz. The indication of support for UL-RS based UE-sided beam sweep procedure (i.e., an U3 procedure) for frequencies above 30 GHz could comprise information as disclosed next.

[0077] The information might specify for which sub-carrier spacings the U3 procedures is supported for (e.g., 960 kHz and / or higher sub-carrier spacing). The information might specify the minimum gap period between two different UE beams. The information might specify a preferred number of UE beams the UE requests to evaluate during the U3 procedure. The number of UE beams can be report per antenna panel, or as one value that is applicable for all antenna panels.

[0078] The information might specify at least a first minimum gap period for switching between beams within one antenna panel and a second minimum gap period for switching between beams belonging to different antenna panels. This is since antenna panel switching might introduce additional delay compared to switching between beams generated at one and the same antenna panel. However, more than two gap periods might be specified, such as per antenna panel, per antenna panel type, or per antenna panel pair, etc. In further detail, the information might specify the number of antenna panels (P), the number of beams per panel (B), as well as up to P-B gap periods, where each of the P-B gap periods is associated with the switching time related to each beam pair per each antenna panel. In another example, the UE can instead indicate a number of gap periods between 1 and P'B. The information might specify the number of simultaneously used antennas, RF front-ends, or PAs, per beam, or the maximum supported number of simultaneously used antennas, RF front-ends, or PAs. This is since the scheduler might allocate time domain SRS resources based on the supported number of simultaneously used antennas, or PAs. As the number of simultaneous antennas, or PAs, is typically proportional to the total transmit power, beams with a larger number of simultaneously used antennas need comparatively smaller number of time domain resources for transmission of the SRS resources to achieve the same UL link budget.

[0079] S302: The gNB configures the UE with SRS resources according to the UE capability signaling. A specified gap period is inserted between the different SRS resources to allow the UE to switch UE beam (either between two beams within one and the same antenna panel or between two beams belonging to different antenna panels).

[0080] S303: The gNB triggers the UE to transmit the SRS resources.

[0081] S304: The UE performs the SRS transmission, while switching UE beam between the different SRS resources. Here, the UE uses the gap period configurations signaled by the gNB in step S302 during the SRS transmissions, and / or the time domain resource configuration.

[0082] S305: The gNB determines a suitable UE beam based on the measured SRS resources and indicates that to the UE.

[0083] S306: The UE uses the indicated beam for coming DL and / or UL communication with the gNB.

[0084] Fig. 8 schematically illustrates, in terms of a number of structural units, the components of a user equipment 800 according to an embodiment. Processing circuitry 810 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 1210a (as in Fig. 12), e.g., in the form of a storage medium 830. The processing circuitry 810 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0085] Particularly, the processing circuitry 810 is configured to cause the user equipment 800 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 830 may store the set of operations, and the processing circuitry 810 may be configured to retrieve the set of operations from the storage medium 830 to cause the user equipment 800 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 810 is thereby arranged to execute methods as herein disclosed.

[0086] The storage medium 830 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. The user equipment 800 may further comprise a communications (comm.) interface 820 for communications with other entities, functions, nodes, and devices, such as the network node 120, 1000, 1100. As such the communications interface 820 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0087] The processing circuitry 810 controls the general operation of the user equipment 800 e.g., by sending data and control signals to the communications interface 820 and the storage medium 830, by receiving data and reports from the communications interface 820, and by retrieving data and instructions from the storage medium 830. Other components, as well as the related functionality, of the user equipment 800 are omitted in order not to obscure the concepts presented herein.

[0088] Fig. 9 schematically illustrates, in terms of a number of functional modules, the components of a user equipment 900 according to an embodiment. The user equipment 900 of Fig. 9 comprises a number of functional modules; a send module 910 configured to perform step S102, a receive module 920 configured to perform step S204, and a transmit module 930 configured to perform step S106. The user equipment 900 of Fig. 9 may further comprise a number of optional functional modules, as represented by functional module 940. In general terms, each functional module 910:940 may be implemented in hardware or in software. Preferably, one or more or all functional modules 910:940 may be implemented by the processing circuitry 810, possibly in cooperation with the communications interface 820 and / or the storage medium 830. The processing circuitry 810 may thus be arranged to from the storage medium 830 fetch instructions as provided by a functional module 910:940 and to execute these instructions, thereby performing any steps of the user equipment 110, 800, 900 as disclosed herein.

[0089] Fig. 10 schematically illustrates, in terms of a number of structural units, the components of a network node 1000 according to an embodiment. Processing circuitry 1010 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 1210b (as in Fig. 12), e.g., in the form of a storage medium 1030. The processing circuitry 1010 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0090] Particularly, the processing circuitry 1010 is configured to cause the network node 1000 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 1030 may store the set of operations, and the processing circuitry 1010 may be configured to retrieve the set of operations from the storage medium 1030 to cause the network node 1000 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 1010 is thereby arranged to execute methods as herein disclosed. The storage medium 1030 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.

[0091] The network node 1000 may further comprise a communications interface 1020 for communications with other entities, functions, nodes, and devices, such as the user equipment 110, 800, 900. As such the communications interface 1020 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0092] The processing circuitry 1010 controls the general operation of the network node 1000 e.g., by sending data and control signals to the communications interface 1020 and the storage medium 1030, by receiving data and reports from the communications interface 1020, and by retrieving data and instructions from the storage medium 1030. Other components, as well as the related functionality, of the network node 1000 are omitted in order not to obscure the concepts presented herein.

[0093] Fig. 11 schematically illustrates, in terms of a number of functional modules, the components of a network node 1100 according to an embodiment. The network node 1100 of Fig. 11 comprises a number of functional modules; a first receive module 1110 configured to perform step S202, a send module 1120 configured to perform step S204, and a second receive module 1130 configured to perform step S206. The network node 1100 of Fig. 11 may further comprise a number of optional functional modules, as represented by functional module 1140. In general terms, each functional module 1110:1140 may be implemented in hardware or in software. Preferably, one or more or all functional modules 1110:1140 may be implemented by the processing circuitry 1010, possibly in cooperation with the communications interface 1020 and / or the storage medium 1030. The processing circuitry 1010 may thus be arranged to from the storage medium 1030 fetch instructions as provided by a functional module 1110:1140 and to execute these instructions, thereby performing any steps of the network node 120, 1000, 1100 as disclosed herein.

[0094] The network node 120, 1000, 1100 may be provided as a standalone device or as a part of at least one further device. For example, the network node 120, 1000, 1100 may be provided in a node of the radio access network or in a node of the core network. Alternatively, functionality of the network node 120, 1000, 1100 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the radio access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time. Thus, a first portion of the instructions performed by the network node 120, 1000, 1100 may be executed in a first device, and a second portion of the instructions performed by the network node 120, 1000, 1100 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the network node 120, 1000, 1100 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a network node 120, 1000, 1100 residing in a cloud computational environment. Therefore, although a single processing circuitry 810 is illustrated in Fig. 8 the processing circuitry 810 may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 1110:1140 of Fig. 9 and the computer program 1220a of Fig. 12.

[0095] Some (radio) access network architectures define network nodes (or gNBs) comprising multiple component parts or nodes: a central unit (CU), one or more distributed units (DUs), and one or more radio units (RUs). The protocol layer stack of the network node is divided between the CU, the DUs and the RUs, with one or more lower layers of the stack implemented in the RUs, and one or more higher layers of the stack implemented in the CU and / or DUs. The CU is coupled to the DUs via a fronthaul higher layer split (HLS) network; the CU / DUs are connected to the RUs via a fronthaul lower-layer split (LLS) network. The DU may be combined with the CU in some embodiments, where a combined DU / CU may be referred to as a CU or simply a baseband unit. A communication link for communication of user data messages or packets between the RU and the baseband unit, CU, or DU is referred to as a fronthaul network or interface. Messages or packets may be transmitted from the network node in the downlink (i.e., from the CU to the RU) or received by the network node in the uplink (i.e., from the RU to the CU).

[0096] Fig. 12 shows one example of a computer program product 1210a, 1210b comprising computer readable means 1230. On this computer readable means 1230, a computer program 1220a can be stored, which computer program 1220a can cause the processing circuitry 810 and thereto operatively coupled entities and devices, such as the communications interface 820 and the storage medium 830, to execute methods according to embodiments described herein. The computer program 1220a and / or computer program product 1210a may thus provide means for performing any steps of the user equipment 110, 800, 900 as herein disclosed. On this computer readable means 1230, a computer program 1220b can be stored, which computer program 1220b can cause the processing circuitry 1010 and thereto operatively coupled entities and devices, such as the communications interface 1020 and the storage medium 1030, to execute methods according to embodiments described herein. The computer program 1220b and / or computer program product 1210b may thus provide means for performing any steps of the network node 120, 1000, 1100 as herein disclosed.

[0097] In the example of Fig. 12, the computer program product 1210a, 1210b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 1210a, 1210b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable readonly memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1220a, 1220b is here schematically shown as a track on the depicted optical disk, the computer program 1220a, 1220b can be stored in any way which is suitable for the computer program product 1210a, 1210b. The inventive concept has 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 inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1. A method for performing an uplink reference signal-based user equipment-sided beam sweep procedure (140), wherein the method is performed by a user equipment (110), and wherein the method comprises: sending (S102) a first message to a network node (120) serving the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); receiving (S104) a second message from the network node (120), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; and transmitting (S106), during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources in different beams (130a: 130B) with the specified gap period between each beam switch.

2. The method according to claim 1, wherein the uplink reference signal-based user equipment-sided beam sweep procedure (140) is performed in a frequency band above 30 GHz.

3. The method according to claim 1 or 2, wherein the beam switch is performed between beams (130a: 130B) generated by one same antenna panel (220a:220P) at the user equipment (110) or between beams (130a: 130B) generated by different antenna panels (220a:220P) at the user equipment (110).

4. The method according to any preceding claim, wherein the capability specifies at least one first required gap period for the user equipment (110) to switch between beams (130a: 130B) generated by one same antenna panel (220a:220P) at the user equipment (110) and / or at least one second required gap period for the user equipment (110) to switch between beams (130a: 130B) generated by two different antenna panels (220a:220P) at the user equipment (110).

5. The method according to any preceding claim, wherein the beams (130a: 130B) are generated by P number of antenna panels (220a:220P) at the user equipment (110), and wherein the capability specifies one required gap period for each pair of antenna panels (220a:220P).

6. The method according to any preceding claim, wherein B number of beams (130a: 130B) are generated per antenna panel (220a:220P) at the user equipment (110), and wherein the capability specifies one required gap period for each pair of beams (130a: 130B).

7. The method according to any preceding claim, wherein the required gap period is specified in terms of any of: milliseconds, microseconds, number of time-domain symbols.

8. The method according to claim 7, wherein the number of time-domain symbols further depends on subcarrier spacings used during the uplink reference signal-based user equipment-sided beam sweep procedure (140).

9. The method according to claim 8, wherein one required gap period is specified per each sub-carrier spacing.

10. The method according to any preceding claim, wherein the capability in the first message further pertains to at least one of: sub-carrier spacings supported by the user equipment (110) for performing the uplink reference signalbased user equipment-sided beam sweep procedure (140), requested number of beams (130a: 130B) at the user equipment (110) to be evaluated during the uplink reference signal-based user equipment-sided beam sweep procedure (140), maximum supported number of simultaneously active antennas (230), power amplifiers, and / or radiofrequency front-ends per beam (130a: 130B).11 . The method according to any preceding claim, wherein number of symbols per each of the uplink reference signal resources depends on maximum supported number of simultaneously active antennas (230), power amplifiers, and / or radio-frequency front-ends per beam (130a: 130B) at the user equipment (110).

12. The method according to any preceding claim, wherein the uplink reference signal-based user equipmentsided beam sweep procedure (140) is performed in a frequency band from 40 GHz to 70 GHz, or from 50 GHz to 150 GHz, or from 250 GHz to 350 GHz.

13. A method for configuring a user equipment (110) for an uplink reference signal-based user equipmentsided beam sweep procedure (140), wherein the method is performed by a network node (120), and wherein the method comprises: receiving (S202) a first message from the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); sending (S204) a second message to the user equipment (110), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period betweentwo consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; and receiving (S206), during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources from the user equipment (110) with the specified gap period between each of the uplink reference signal resources.

14. The method according to claim 13, wherein the uplink reference signal-based user equipment-sided beam sweep procedure (140) is performed in a frequency band above 30 GHz.

15. The method according to claim 13 or 14, wherein the capability specifies at least one first required gap period for the user equipment (110) to switch between beams (130a: 130B) generated by one same antenna panel (220a:220P) at the user equipment (110) and / or at least one second required gap period for the user equipment (110) to switch between beams (130a: 130B) generated by two different antenna panels (220a:220P) at the user equipment (110).

16. The method according to any of claims 13 to 15, wherein the capability specifies one required gap period for each pair of antenna panels (220a:220P) at the user equipment (110).

17. The method according to any of claims 13 to 16, wherein the capability specifies one required gap period for each pair of beams (130a: 130B) per antenna panel (220a:220P) at the user equipment (110).

18. The method according to any of claims 13 to 17, wherein the required gap period is specified in terms of any of: milliseconds, microseconds, number of time-domain symbols.

19. The method according to any of claims 13 to 18, wherein the capability in the first message further pertains to at least one of: sub-carrier spacings supported by the user equipment (110) for performing the uplink reference signalbased user equipment-sided beam sweep procedure (140), requested number of beams (130a: 130B) at the user equipment (110) to be evaluated during the uplink reference signal-based user equipment-sided beam sweep procedure (140), maximum supported number of simultaneously active antennas (230), power amplifiers, and / or radiofrequency front-ends per beam (130a: 130B).

20. The method according to any of claims 13 to 19, wherein number of symbols per each of the uplink reference signal resources depends on maximum supported number of simultaneously active antennas (230), power amplifiers, and / or radio-frequency front-ends per beam (130a: 130B) at the user equipment (110).21 . The method according to any of claims 13 to 20, wherein the uplink reference signal-based user equipment-sided beam sweep procedure (140) is performed in a frequency band from 40 GHz to 70 GHz, or from 50 GHz to 150 GHz, or from 250 GHz to 350 GHz.

22. A user equipment (110, 800) for performing an uplink reference signal-based user equipment-sided beam sweep procedure (140), the user equipment (110, 800) comprising processing circuitry (810), the processing circuitry being configured to cause the user equipment (110, 800) to: send a first message to a network node (120) serving the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipmentsided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); receive a second message from the network node (120), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; and transmit, during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources in different beams (130a: 130B) with the specified gap period between each beam switch.

23. A user equipment (110, 900) for performing an uplink reference signal-based user equipment-sided beam sweep procedure (140), the user equipment (110, 900) comprising: a send module (910) configured to send a first message to a network node (120) serving the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); a receive module (920) configured to receive a second message from the network node (120), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; anda transmit module (930) configured to transmit, during the uplink reference signal-based user equipmentsided beam sweep procedure (140), the uplink reference signal resources in different beams (130a: 130B) with the specified gap period between each beam switch.

24. The user equipment (110, 800, 900) according to claim 22 or 23, further being configured to perform the method according to any of claims 2 to 12.

25. A network node (120, 1000) for configuring a user equipment (110) for an uplink reference signal-based user equipment-sided beam sweep procedure (140), the network node (120, 1000) comprising processing circuitry (1010), the processing circuitry being configured to cause the network node (120, 1000) to: receive a first message from the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); send a second message to the user equipment (110), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; and receive, during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources from the user equipment (110) with the specified gap period between each of the uplink reference signal resources.

26. A network node (120, 1100) for configuring a user equipment (110) for an uplink reference signal-based user equipment-sided beam sweep procedure (140), the network node (120, 1100) comprising: a first receive module (1110) configured to receive a first message from the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); a send module (1120) configured to send a second message to the user equipment (110), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; anda second receive module (1130) configured to receive, during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources from the user equipment (110) with the specified gap period between each of the uplink reference signal resources.

27. The network node (120, 1000, 1100) according to claim 25 or 26, further being configured to perform the method according to any of claims 14 to 21 .

28. A computer program (1220a) for performing an uplink reference signal-based user equipment-sided beam sweep procedure (140), the computer program comprising computer code which, when run on processing circuitry (810) of a user equipment (110, 800), causes the user equipment (110, 800) to: send (S102) a first message to a network node (120) serving the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); receive (S104) a second message from the network node (120), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; and transmit (S106), during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources in different beams (130a: 130B) with the specified gap period between each beam switch.

29. A computer program (1220b) for configuring a user equipment (110) for an uplink reference signal-based user equipment-sided beam sweep procedure (140), the computer program comprising computer code which, when run on processing circuitry (1010) of a network node (120, 1000), causes the network node (120, 1000) to: receive (S202) a first message from the user equipment (110), wherein the first message indicates a capability of the user equipment (110) to perform the uplink reference signal-based user equipment-sided beam sweep procedure (140), and wherein the capability specifies at least a required gap period for the user equipment (110) to switch beams (130a: 130B) during the beam sweep procedure (140); send (S204) a second message to the user equipment (110), wherein the second message comprises an uplink reference signal configuration for a set of uplink reference signal resources to be transmitted in the beams (130a: 130B), wherein the uplink reference signal configuration comprises a specified gap period between two consecutive uplink reference signal resources, and wherein the specified gap period is at least as long as the required gap period; andreceive (S206), during the uplink reference signal-based user equipment-sided beam sweep procedure (140), the uplink reference signal resources from the user equipment (110) with the specified gap period between each of the uplink reference signal resources.

30. A computer program product (1210a, 1210b) comprising a computer program (1220a, 1220b) according to at least one of claims 28 and 29, and a computer readable storage medium (1230) on which the computer program is stored.

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