Beam management procedure status indication

Abstract

There is provided techniques for receiving beam management procedure status indication from a UE. A method is performed by a network node. The method comprises transmitting, as part of performing a beam management procedure, a downlink reference signal in a set of beams. The method comprises performing an initial access procedure with the UE. As part of performing the initial access procedure, the network node receives an indication from the UE of a beam in the set of beams. The method comprises receiving a status indication from the UE during the initial access procedure. The method comprises performing a communication procedure with the UE. Which communication procedure to be performed is dependent on the received status indication.

Description

[0001] BEAM MANAGEMENT PROCEDURE STATUS INDICATION

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to a method, a network node, a computer program, and a computer program product for receiving beam management procedure status indication from a user equipment. Embodiments presented herein further relate to a method, a user equipment, a computer program, and a computer program product for providing the beam management procedure status indication to the network node.

[0004] BACKGROUND

[0005] Before a user equipment (UE) can properly communicate within a network, the UE must carry out a cell search procedure to find, synchronize and identify a cell. Then, the UE can acquire basic system information and perform an initial access procedure to establish a connection to the cell.

[0006] Taking the New Radio (NR) as a non-limiting illustrative example, the combination of synchronization signals (SS) and physical broadcast channel (PBCH) is referred to as an SS / PBCH block (SSB). Similar to the Long Term Evolution (LTE) air interface, a pair of SSs, namely a primary synchronization signal (PSS) and secondary synchronization signal (SSS), is periodically transmitted in the downlink from each cell to allow the UE to initiate initial access to the network. By detecting SSs, a UE can obtain the physical cell identity (PCI), achieve downlink synchronization in both time and frequency, and acquire the timing for the PBCH. The PBCH carries the master information block (MIB), which contains a minimum system information that a UE needs to acquire system information block 1 (SIB1). SIB1 carries the remaining minimum system information that is needed for a UE to be able to perform subsequent random-access procedure. The SIB1 information is transmitted on a physical downlink shared channel (PDSCH) and scheduling information, needed by the UE to find and decode the PDSCH, is transmitted on a physical downlink control channel (PDCCH).

[0007] The SSB periodicity can take different values (5 ms, 10 ms, 20 ms, 40ms, 80 ms, 160 ms). For initial access, the UE assumes an SSB periodicity of 20 ms. Within one SSB period, the SSBs can be transmitted in a burst confined in one half frame (5 ms). The maximum number (denoted L) of SSBs in one burst is determined by the sub-carrier spacing. For frequency range from 24.24GHz to 52.6GHz, L can be as large as 64.

[0008] A signal diagram of a 4-step initial access procedure 100, also referred to as Type-1 initial access procedure in 3GPP TS 38.213 "NR; Physical layer procedures for control”, version 18.4.0, is provided in Fig. 1. In a first step, the UE initiates the random-access procedure by transmitting a random-access preamble (Msg1) on a physical random-access channel (PRACH). After detecting the Msg1, the network node, in a second step, responds by transmitting a random-access response (RAR), or Msg2, on the PDSCH. In a third step, after successfully decoding Msg2, the UE continues the procedure by transmitting Msg3 on the PUSCH for terminal identification and radio resource control (RRC) connection establishment request. In a fourth step, the network node transmits Msg4 on the PDSCH for contention resolution. There can be cases where multiple UEs select the same random- access preamble and transmit the preamble on the same PRACH time / frequency resource. This preamble collision is called contention. One of the main purposes of applying the third and fourth steps is to resolve such potential contention.

[0009] A signal diagram of a 2-step initial access procedure 200, also referred to as Type-2 initial access procedure in aforementioned 3GPP TS 38.213, is provided in Fig. 2. In the first step, the UE sends on the PUSCH a message A (MsgA), including a random access preamble and higher layer data, such as RRC connection request, possibly with some small payload. After detecting the MsgA, the network in a second step sends a random access response (RAR) called message B (MsgB), comprising UE identifier assignment, timing advance information, and contention resolution message etc.

[0010] Msg1 and MsgA can both be referred to as random access initiation messages. In general, the random access initiation message (for both the 4-step and the 2-step initial access procedures) indicates a suitable SSB. Here, the UE may report an SSB that is received with a reference signal received power (RSRP) over a certain threshold. That is, the UE is not mandated to transmit a random access initiation message associated with the SSB received with highest RSRP. Hence, the UEs may only select and transmit a random access initiation message associated with an SSB for which the RSRP is above the threshold, and not the SSB for which the RSRP was highest.

[0011] A beam management procedure can be performed in order to identify a beam pair link (BPL) for communication between the network node and the UE. The BPL is defined by one beam as used by the network node and one beam as used by the UE. However, at least part of the beam management procedure may be unnecessary in case the UE has already performed measurements on some of the SSBs. Hence, performing a complete beam management procedure may cause unnecessary delay and / or signaling overhead.

[0012] SUMMARY

[0013] An object of embodiments herein is to address the aforementioned issues to enable more efficient beam management procedures.

[0014] A particular object is to enable the network node to identify whether any part, parts, of the beam management procedure can be skipped for a UE.

[0015] According to a first aspect there is presented a method for receiving beam management procedure status indication from a UE. The method is performed by a network node. The method comprises transmitting, as part of performing a beam management procedure, a downlink reference signal in a set of beams. The method comprises performing an initial access procedure with the UE. As part of performing the initial access procedure, the network node receives an indication from the UE of a beam in the set of beams. The method comprises receiving a status indication from the UE during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of the beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. The method comprises performing a communication procedure with the UE. Which communication procedure to be performed is dependent on the received status indication.

[0016] According to a second aspect there is presented a network node for receiving beam management procedure status indication from a UE, the network node comprising processing circuitry. The processing circuitry is configured to cause the network node to transmit, as part of performing a beam management procedure, a downlink reference signal in a set of beams. The processing circuitry is configured to cause the network node to perform an initial access procedure with the UE. As part of performing the initial access procedure, the network node receives an indication from the UE of a beam in the set of beams. The processing circuitry is configured to cause the network node to receive a status indication from the UE during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of the beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. The processing circuitry is configured to cause the network node to perform a communication procedure with the UE. Which communication procedure to be performed is dependent on the received status indication.

[0017] According to a third aspect there is presented a computer program for receiving beam management procedure status indication from a UE. 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 transmit, as part of performing a beam management procedure, a downlink reference signal in a set of beams. One action comprises the network node to perform an initial access procedure with the UE. As part of performing the initial access procedure, the network node receives an indication from the UE of a beam in the set of beams. One action comprises the network node to receive a status indication from the UE during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of the beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. One action comprises the network node to perform a communication procedure with the UE. Which communication procedure to be performed is dependent on the received status indication.

[0018] According to a fourth aspect there is presented a method for providing beam management procedure status indication to a network node. The method is performed by a UE. The method comprises performing a measurement on a downlink reference signal as having been transmitted by the network node in a set of beams. The method comprises performing an initial access procedure with the network node. As part of performing the initial access procedure, the UE sends an indication of one beam in the set of beams. The method comprises sending a status indication of the UE to the network node during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of a beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. The method comprises performing a communication procedure with the network node. Which communication procedure to be performed is dependent on the sent status indication.

[0019] According to a fifth aspect there is presented a UE for providing beam management procedure status indication to a network node, the UE comprising processing circuitry. The processing circuitry is configured to cause the UE to perform a measurement on a downlink reference signal as having been transmitted by the network node in a set of beams. The processing circuitry is configured to cause the UE to perform an initial access procedure with the network node. As part of performing the initial access procedure, the UE sends an indication of a beam in the set of beams. The processing circuitry is configured to cause the UE to send a status indication of the UE to the network node during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of a beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. The processing circuitry is configured to cause the UE to perform a communication procedure with the network node. Which communication procedure to be performed is dependent on the sent status indication.

[0020] According to a sixth aspect there is presented a computer program for providing beam management procedure status indication to a network node. 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 perform a measurement on a downlink reference signal as having been transmitted by the network node in a set of beams. One action comprises the UE to perform an initial access procedure with the network node. As part of performing the initial access procedure, the UE sends an indication of a beam in the set of beams. One action comprises the UE to send a status indication of the UE to the network node during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE has participated in at least part of a beam management procedure or not, whether the indication of said beam was of a beam in the set of beams for which the downlink reference signal was received with highest received power by the UE or not. One action comprises the UE to perform a communication procedure with the network node. Which communication procedure to be performed is dependent on the sent status indication.

[0021] According to a seventh aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect and the sixth 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. Advantageously, by means of the status indication as received from the U E, the network node is can decide whether the network node needs to perform any beam management procedure with the UE or not before scheduling the UE with data transmissions, etc.

[0022] Advantageously, these aspects enable savings with respect to latency and signaling overhead. In turn, this enables improvements in terms of UE energy efficiency (as the UE does not need to re-perform beam measurements).

[0023] In this way, the herein disclosed embodiments can improve the performance for UEs with low latency requirements as well as for UEs with low energy levels.

[0024] 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.

[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, 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.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0028] Figs. 1 and 2 are signaling diagrams of initial access procedures according to examples;

[0029] Fig. 3 is a schematic diagram illustrating a communication network according to embodiments;

[0030] Figs. 4 and 5 are flowcharts of methods according to embodiments;

[0031] Fig. 6 is a schematic diagram showing structural units of a network node according to an embodiment;

[0032] Fig. 7 is a schematic diagram showing structural units of a UE according to an embodiment; and

[0033] Fig. 8 shows one example of a computer program product comprising computer readable means according to an embodiment.

[0034] DETAILED DESCRIPTION

[0035] 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.

[0036] Fig. 3 is a schematic diagram illustrating a communication network 300 where embodiments presented herein can be applied. The communication network 300 comprises a network node 310 that, via transmission and reception point (TRP) 320, is configured to provide network access, and thus network coverage, to a UE 330 located in a cell served by the network node 310. The network node 310 could be any of a (radio) access network node, radio base station, base transceiver station, node B (NB), evolved node B (eNB), gNB, access point, access node, integrated access and backhaul (IAB) node. The UE 330 could be any of a portable wireless device, mobile station, mobile phone, handset, wireless local loop phone, smartphone, laptop computer, tablet computer, wireless modem, wireless sensor device, network equipped vehicle, Internet of Things (loT) device, game controller.

[0037] At least the network node 310 is configured to, via the TRP 320, perform beamformed transmission and reception in a set of beams 340. In the illustrative example of Fig. 3, the set of beams 340 comprises three beams 360a, 360b, 360c, but generally the set of beams 340 may comprise a plurality of beams. Further, the set of beams 340 may comprise different subsets of beams with different beamwidths. A beam sweep may be performed as indicated by arrow 350. In some aspects, also the UE 330 is configured to perform beamformed transmission and reception in a set of beams 370. In the illustrative example of Fig. 3, the set of beams 370 comprises three beams, but generally the set of beams 370 may comprise a plurality of beams. Further, the set of beams 370 may comprise different subsets of beams with different beamwidths. A beam sweep may be performed as indicated by arrow 380.

[0038] In general terms, a beam management procedure can be performed in order to identify a beam pair link (BPL) for communication between the network node 310 and the UE 330. The BPL is defined by one beam as used by the network node 310 (i.e., one of the beams 360a, 360b, 360c in the set of beams 340) and one beam as used by the UE 330 (i.e., one of the beams in the set of beams 370). In further detail, 3GPP has in 3GPP TR 38.802 "Study on new radio access technology Physical layer aspects”, version 14.2.0, section 6.1.6, defined layer 1 and layer 2 beam management procedures. Procedure 1 (P1) represents an initial access procedure, Procedure 2 (P2) is used for beam refinement and tracking at the network node, and Procedure 3 (P3) is used for UE beam refinement. The procedures P1, P2, and P3 can be summarized as follows. For the P1 procedure the network node broadcasts SSBs in the downlink in a set of wide beams such that the UE, using a beam for reception of the SSBs, is able to measure and send a random-access preamble for the beam corresponding to the strongest SSB. SSBs are transmitted over a set of wide beams to cover several UEs at the same time. After the initial access is completed, the network node triggers a procedure to identify the best narrow beam within the strongest wide beam that was identified during the P1 procedure. Typically, the P2 procedure involves the network node to transmit channel state information reference signals (CSI-RSs) in the downlink in a set of narrow beams such that the UE, using a beam for reception of the CSI-RSs, is able to measure and report (such as in a CSI report) at least the narrow beam for which the RSRP was highest. In case the UE is capable of beamforming, a P3 procedure can be performed where the network transmits CSI-RSs in the downlink in the beam identified in the P2 procedure as the best for serving the UE such that the UE, using a set of beams for reception of the CSI-RSs, is able to identify which of the narrow beams is the best for subsequent communication with the network node.

[0039] As noted above at least part of the beam management procedure may be unnecessary in case the UE has already performed measurements on some of the SSBs. Performing a complete beam management procedure may therefore, in some cases, cause unnecessary delay and / or signaling overhead.

[0040] Further, different UEs may have different properties in terms of type and number of antenna panels, number of transmit and receive chains, antenna elements per antenna panel, etc. Information about these properties may help the network node to properly serve the UE with low latency, e.g., by scheduling an appropriate rank without additional channel state information reports. At least some of the herein disclosed embodiments are therefore based on providing such information as early as possible to the network node.

[0041] In particular, at least some of the herein disclosed embodiments are based on reducing signaling overhead and latency of the beam management procedure based on an early status indication as provided from the UE to the network node during initial access. As will be disclosed in further detail below, the status indication may comprise information about whether the UE has performed at least part of any of the aforementioned P1-P3 procedures or not, an estimation of the channel quality associated with the indicated SSB, information about the number of transmit and / or receive chains associated with the antenna panel used at the UE to receive the indicated SSB, etc. The network node could then perform the appropriate actions based on the received status indication. As will be disclosed in further detail below, the actions may comprise canceling one or more steps of the management procedure, scheduling the UE with, e.g., certain transmission ranks, etc.

[0042] Reference is now made to Fig. 4 illustrating a method for receiving beam management procedure status indication from a UE 330 as performed by the network node 310 according to an embodiment.

[0043] S102: The network node 310 transmits, as part of performing a beam management procedure, a downlink reference signal in a set of beams 340.

[0044] S104: The network node 310 performs an initial access procedure with the UE 330. As part of performing the initial access procedure, the network node 310 receives an indication from the UE 330 of a beam 360c in the set of beams 340.

[0045] S106: The network node 310 receives a status indication from the UE 330 during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE 330 has participated in at least part of the beam management procedure or not, whether the indication of said beam 360c was of a beam in the set of beams 340 for which the downlink reference signal was received with highest received power by the UE 330 or not.

[0046] The status indication enables the network node to reduce latency and / or overhead signaling associated with the beam management procedure.

[0047] S108: The network node 310 performs a communication procedure with the UE 330. Which communication procedure to be performed is dependent on the received status indication.

[0048] Embodiments relating to further details of receiving beam management procedure status indication from a UE 330 as performed by the network node 310 will now be disclosed.

[0049] As disclosed above, as part of performing the initial access procedure, the network node 310 receives an indication from the UE 330 of a beam 360c in the set of beams 340. Here, each of the beams 360a: 360c in the set of beams 340 may have a respective beam index that is transmitted together with the downlink reference signal, and the indication received from the UE 330 of said beam 360c in the set of beams 340 can then be the beam index of said beam 360c in the set of beams 340.

[0050] There may be different ways in which the UE 330 can send the status indication during (or immediately after) the initial access procedure. For example, the status indication may be received from the UE 330 during the aforementioned four-step initial access procedure 100, during the aforementioned two-step initial access procedure 200, during some other type of initial access procedure, via a physical random access channel transmission from the UE 330, or via some other transmission from the UE 330.

[0051] Further aspects of the status indication will be disclosed next.

[0052] In some embodiments, the status indication comprises channel measurements (e.g., RSRP, reference signal received quality (RSRQ), signal to noise ratio (SNR), signal to interference plus noise ratio (SINR), etc.) made by the UE 330 based on the downlink reference signal as transmitted in said beam 360c.

[0053] In some examples, the status indication provides information of where the downlink reference signal associated with the indicated beam 360c ranks among the strongest N downlink reference signals measured by the UE 330 (e.g., that the indicated beam 360c is associated with the downlink reference signal received with highest RSRP, received with second highest RSRP, received with third highest RSRP, etc. Hence, in some embodiments, the status indication comprises an indication of how said beam 360c ranks among the beams 360a:360c in the set of beams 340 with respect to level of received power by the UE 330 of the downlink reference signal as transmitted in the beams 360a:360c in the set of beams 340. For instance, a flag indicator may indicate whether the indicated beam 360c is associated with the downlink reference signal with highest RSRP or not. In another example, a flag indicator may indicate whether the UE has performed at least part of the aforementioned steps P1-P3 of the beam management procedure or not.

[0054] In some embodiments, the status indication comprises an indication (e.g., an SSB index and its associated RSRP) of N beams 360a:360c in the set of beams 340 for which the downlink reference signal was received with highest received power by the UE 330, where N>1 is an integer.

[0055] In some embodiments, the status indication comprises information of number of radio chains (i.e., transmit and receive chains) associated with an antenna panel used by the UE 330 for receiving the downlink reference signal transmitted in said beam 360c. For example, the UE may indicate if the number of radio chains is equal to 1 or larger than one. If the antenna panel is associated with one single radio chain, this is a single-polarized panel. Likewise, if the antenna panel is associated with two or more radio chains, the antenna panel may have two orthogonal polarizations (and hence be dual-polarized). In some embodiments, the status indication comprises information of polarization of an antenna panel used by the UE 330 for receiving the downlink reference signal transmitted in said beam 360c (e.g., whether the antenna panel is single-polarized or dual-polarized). Since the transmission between a TRP and UE may use a single narrow beam at both the TRP and the UE, it may only be possible to either use a single layer transmission in case the antenna panel has a single-polarized antenna array or use two-layer transmission incase the UE has a dual-polarized antenna panel. Hence, by indicating if the UE has one radio chain or more than one radio chain the network node may know whether the network node can apply single-layer transmission or dual-layer transmission when communicating with the UE.

[0056] In some embodiments, the status indication comprises information of (the maximum) transmission and / or reception rank associated with the antenna panel used by the UE 330 for receiving the downlink reference signal transmitted in said beam 360c. In this respect, the UE may here only indicate if the associated antenna panel supports only single-layer transmission and / or reception or more than one layer transmission and / or reception. Further, the network node may determine the rank for communication with the UE based on, e.g., the estimated channel quality (e.g., RSRP, SINR, etc.) received from the UE, information obtained about the antenna panel used to receive the indicated downlink reference signal, etc. This will help the network node to properly serve the UE with low latency, by scheduling an appropriate rank without additional channel state information reports.

[0057] In some embodiments, the status indication comprises information (e.g., in terms of UE panel identifier, UE panel type identifier, etc.) of an antenna panel used by the UE 330 for receiving the downlink reference signal.

[0058] In some embodiments, the status indication comprises information of how many antenna panels have been used by the UE 330 for evaluating the reference signal as transmitted in the set of beams 340. Here, if the UE indicates that it has measured and evaluated all or some of its antenna panels during initial access, the UE may not have to now transmit uplink reference signals from all the antenna panels at a later instance (e.g., as part of a beam management procedure) after initial access. In some embodiments, the status indication comprises an indication of for which of the beams 360a:360c in the set of beams 340 the UE 330, as part of having participated in at least part of the beam management procedure, has performed a respective beam sweep 370 for. For example, the status indication may comprise an indication of whether the UE has performed the aforementioned P3 procedure for all beams in the set of beams 340, for more than one but less than all of the beams in the set of beams 340, or for only the indicated beams 360c. For example, the status indication may comprise an indication of that the UE has performed a complete beam sweep 370 (i.e., a complete P3 procedure) for all beams in the set of beams 340. For example, the status indication may comprise an indication of that the UE has performed a complete beam sweep 370 (i.e., a complete P3 procedure) for the indicated beams 360c. For example, the status indication may comprise an indication of that the UE has performed a complete P1 procedure (i.e., that the UE has measured and evaluated the RSRP for all beams 360a:360c associated with the initial access).

[0059] As disclosed above, which communication procedure the network node 310 performs in step S108 is dependent on the received status indication. In this respect, there can be different actions performed by the network node 310. In some embodiments, the communication procedure comprises at least one of: cancelling at least one step of the beam management procedure with the UE 330, performing at least part of the beam management procedure with the UE 330 for beams 360a, 360b in the set of beams 340 not indicated in the status indication, determining transmission rank for communication with the UE 330, scheduling the UE 330 for data transmission based on the status indication.

[0060] In further detail, the network node may analyze if, e.g., the downlink reference signal associated with the indicated beam provides an RSRP above a certain satisfactory performance threshold (e.g., sufficient to guarantee a certain link throughput). If this is not the case, the network node may not use information obtained in the status indication and therefore perform complete P1-P3 procedures. On the other hand, if this is the case (i.e., that the downlink reference signal associated with the indicated beam indeed provides an RSRP above a certain satisfactory performance threshold), the network node can use the information obtained in the status indication as follow.

[0061] For instance, if the network node understands that the indicated beam is associated with the downlink reference signal for which the RSRP is highest, the network node may cancel the beam management procedure after the initial access and directly schedule the UE with data transmission based on the received indication. Alternatively, if the network node understands that one or more of the steps P1-P3 have been performed by the UE during (or immediately after) the initial access procedure, the network node may cancel those steps during the beam management procedure as performed following the initial access.

[0062] How the network node made trigger one of the steps e.g., P1-P3 of the beam management procedure without using beams reported during status will be disclosed next. The network node may still trigger a P1 procedure after the random-access procedure is completed, but the network node may omit performing a beam sweep 350 in some of the beams for which information has been reported in the status indication. For example, the network node may omit performing the beam sweep 350 in the beam 360c for which an indication was received in step S104 in an upcoming P1 procedure. This is since the network node then already knows the RSRP associated with this beam. In general terms, the network node may omit performing the beam sweep 350 in (some of) the beams for which the network node has obtained associated RSRPs.

[0063] Further, in some embodiments, which communication procedure to be performed further is dependent on at least one of: a quality-of-service requirement for the UE 330, received power at the UE 330 of the downlink reference as transmitted in said beam 360c, a latency requirement for the UE 330, a network node subscription of the UE 330.

[0064] For example, if the RSRP of the indicated downlink reference signal is above a threshold, i.e., RSRP > x dB where, e.g., x = -10 dB, the network node may cancel one or more steps of the beam management procedure. On the other hand, with RSRP < x dB, the network node may still perform the complete beam management procedure. In another example, if the UE subscription implies another threshold y, i.e., that RSRP needs to exceed y, where y is a threshold determined based on the UE subscription (e.g., y = -10 dB), and the received RSRP satisfies this threshold, the network node may cancel at least part of the beam management procedure. In yet another example, if the UE requires a latency less than a threshold T, i.e., latency < T, the network node may cancel part of the beam management procedure when the status indication indicates that at least part of the beam management procedure has been performed during (or immediately after) the initial access. On the other hand, with a relaxed latency requirement, the network node may still perform at least part of the beam management procedure after the initial access.

[0065] In this way, the status indication as provided by the UE to the network node during (or immediately after) the initial access enables the network node to determine whether one or more steps of the beam management procedures following the initial access can be skipped, and even if the network node can directly serve the UE with data transmission. This not only reduces the latency and signaling overhead, but also improves the UE energy efficiency since redundant beam management and reports are avoided.

[0066] Reference is now made to Fig. 5 illustrating a method for providing beam management procedure status indication to a network node 310 as performed by the UE 330 according to an embodiment.

[0067] S202: The UE 330 performs a measurement on a downlink reference signal as having been transmitted by the network node 310 in a set of beams 340.

[0068] S204: The UE 330 performs an initial access procedure with the network node 310. As part of performing the initial access procedure, the UE 330 sends an indication of a beam 360c in the set of beams 340. S206: The UE 330 sends a status indication of the UE 330 to the network node 310 during (or immediately after) the initial access procedure. The status indication specifies at least one of: whether the UE 330 has participated in at least part of a beam management procedure or not, whether the indication of said beam 360c was of a beam in the set of beams 340 for which the downlink reference signal was received with highest received power by the UE 330 or not.

[0069] S208: The UE 330 performs a communication procedure with the network node 310. Which communication procedure to be performed is dependent on the sent status indication.

[0070] Embodiments relating to further details of providing beam management procedure status indication to a network node 310 as performed by the UE 330 will now be disclosed.

[0071] As disclosed above, in some embodiments, each of the beams 360a:360c in the set of beams 340 has a respective beam index that is transmitted together with the downlink reference signal, and the indication sent from the UE 330 of said beam 360c in the set of beams 340 is the beam index of said beam 360c in the set of beams 340.

[0072] As disclosed above, in some embodiments, the measurement is performed as part of the UE 330 participating in at least part of the beam management procedure.

[0073] All aspects, embodiments, and examples relating to the status indication as disclosed above with respect to the network node apply also to the UE. This is especially the case since it is the UE that sends the status indication of the UE 330 to the network node 310, and hence the UE has access to all information that is sent in the status indication.

[0074] Fig. 6 schematically illustrates, in terms of a number of structural units, the components of a network node 600 according to an embodiment. Processing circuitry 610 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 810a (as in Fig. 8), e.g. in the form of a storage medium 630. The processing circuitry 610 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0075] Particularly, the processing circuitry 610 is configured to cause the network node 600 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 630 may store the set of operations, and the processing circuitry 610 may be configured to retrieve the set of operations from the storage medium 630 to cause the network node 600 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 610 is thereby arranged to execute methods as herein disclosed. The storage medium 630 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.

[0076] The network node 600 may further comprise a communications (comm.) interface 620 for communications with other entities, functions, nodes, and devices, as in Fig. 3. As such the communications interface 620 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0077] The processing circuitry 610 controls the general operation of the network node 600 e.g. by sending data and control signals to the communications interface 620 and the storage medium 630, by receiving data and reports from the communications interface 620, and by retrieving data and instructions from the storage medium 630. Other components, as well as the related functionality, of the network node 600 are omitted in order not to obscure the concepts presented herein.

[0078] The network node 600 may be provided as a standalone device or as a part of at least one further device. For example, the network node 600 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 600 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 a radio access network or a 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 600 may be executed in a first device, and a second portion of the instructions performed by the network node 600 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 600 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a network node 600 residing in a cloud computational environment. Therefore, although a single processing circuitry 610 is illustrated in Fig. 6 the processing circuitry 610 may be distributed among a plurality of devices, or nodes. The same applies to the computer program 820a of Fig. 8.

[0079] Moreover, a network node 600 is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the network node may be an open radio access network (ORAN) network node. An ORAN network node is a network node that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other network nodes to implement one or more functionalities of any network node, including one or more access network nodes and / or core network nodes. Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective "open” designating support of an ORAN specification). An ORAN network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1, F1, W1, E1, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN network node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies.

[0080] Fig. 7 schematically illustrates, in terms of a number of structural units, the components of a UE 700 according to an embodiment. Processing circuitry 710 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 810b (as in Fig. 8), e.g. in the form of a storage medium 730. The processing circuitry 710 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0081] Particularly, the processing circuitry 710 is configured to cause the UE 700 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 730 may store the set of operations, and the processing circuitry 710 may be configured to retrieve the set of operations from the storage medium 730 to cause the UE 700 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 710 is thereby arranged to execute methods as herein disclosed.

[0082] The storage medium 730 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.

[0083] The UE 700 may further comprise a communications interface 720 for communications with other entities, functions, nodes, and devices, as in Fig. 3. As such the communications interface 720 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0084] The processing circuitry 710 controls the general operation of the UE 700 e.g. by sending data and control signals to the communications interface 720 and the storage medium 730, by receiving data and reports from the communications interface 720, and by retrieving data and instructions from the storage medium 730. Other components, as well as the related functionality, of the UE 700 are omitted in order not to obscure the concepts presented herein.

[0085] Fig. 8 shows one example of a computer program product 810a, 810b comprising computer readable means 830. On this computer readable means 830, a computer program 820a can be stored, which computer program 820a can cause the processing circuitry 610 and thereto operatively coupled entities and devices, such as the communications interface 620 and the storage medium 630, to execute methods according to embodiments described herein. The computer program 820a and / or computer program product 810a may thus provide means for performing any steps of the network node 310, 600 as herein disclosed. On this computer readable means 830, a computer program 820b can be stored, which computer program 820b can cause the processing circuitry 710 and thereto operatively coupled entities and devices, such as the communications interface 720 and the storage medium 730, to execute methods according to embodiments described herein. The computer program 820b and / or computer program product 810b may thus provide means for performing any steps of the UE 330, 700 as herein disclosed.

[0086] In the example of Fig. 8, the computer program product 810a, 810b 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 810a, 810b 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 read-only 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 820a, 820b is here schematically shown as a track on the depicted optical disk, the computer program 820a, 820b can be stored in any way which is suitable for the computer program product 810a, 810b.

[0087] 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 receiving beam management procedure status indication from a user equipment, UE (330, 700), wherein the method is performed by a network node (310, 600), and wherein the method comprises: transmitting (S102), as part of performing a beam management procedure, a downlink reference signal in a set of beams (340); performing (S104) an initial access procedure with the UE (330, 700), where, as part of performing the initial access procedure, the network node (310, 600) receives an indication from the UE (330, 700) of a beam (360c) in the set of beams (340); receiving (S106) a status indication from the UE (330, 700) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of the beam management procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and performing (S108) a communication procedure with the UE (330, 700), wherein which communication procedure to be performed is dependent on the received status indication.

2. The method according to claim 1, wherein each of the beams (360a:360c) in the set of beams (340) has a respective beam index that is transmitted together with the downlink reference signal, and wherein the indication received from the UE (330, 700) of said beam (360c) in the set of beams (340) is the beam index of said beam (360c) in the set of beams (340).

3. The method according to claim 1 or 2, wherein the initial access procedure is a four-step initial access procedure (100) or a two-step initial access procedure (200).

4. The method according to any preceding claim, wherein the status indication is received via a physical random access channel transmission from the UE (330, 700).

5. The method according to any preceding claim, wherein the status indication comprises channel measurements made by the UE (330, 700) based on the downlink reference signal as transmitted in said beam (360c).

6. The method according to any preceding claim, wherein the status indication comprises an indication of how said beam (360c) ranks among the beams (360a: 360c) in the set of beams (340) with respect to level of received power by the UE (330, 700) of the downlink reference signal as transmitted in the beams (360a:360c) in the set of beams (340).

7. The method according to any preceding claim, wherein the status indication comprises an indication of N beams (360a:360c) in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700), where N>1 is an integer.

8. The method according to any preceding claim, wherein the status indication comprises information of number of radio chains associated with an antenna panel used by the UE (330, 700) for receiving the downlink reference signal transmitted in said beam (360c).

9. The method according to any preceding claim, wherein the status indication comprises information of transmission and / or reception rank associated with an antenna panel used by the UE (330, 700) for receiving the downlink reference signal transmitted in said beam (360c).

10. The method according to any preceding claim, wherein the status indication comprises information of polarization of an antenna panel used by the UE (330, 700) for receiving the downlink reference signal transmitted in said beam (360c).11 . The method according to any preceding claim, wherein the status indication comprises information of an antenna panel used by the UE (330, 700) for receiving the downlink reference signal.

12. The method according to any preceding claim, wherein the status indication comprises information of how many antenna panels have been used by the UE (330, 700) for evaluating the reference signal as transmitted in the set of beams (340).

13. The method according to any preceding claim, wherein the status indication comprises an indication of for which of the beams (360a:360c) in the set of beams (340) the UE (330, 700), as part of having participated in at least part of the beam management procedure, has performed a respective beam sweep (370) for.

14. The method according to any preceding claim, wherein the communication procedure comprises at least one of:- cancelling at least one step of the beam management procedure with the UE (330, 700),- performing at least part of the beam management procedure with the UE (330, 700) for beams (360a, 360b) in the set of beams (340) not indicated in the status indication,- determining transmission rank for communication with the UE (330, 700),- scheduling the UE (330, 700) for data transmission based on the status indication.

15. The method according to any preceding claim, wherein which communication procedure to be performed further is dependent on at least one of: a quality-of-service requirement for the UE (330, 700), received power at the UE (330, 700) of the downlink reference as transmitted in said beam (360c), a latency requirement for the UE (330, 700), a network subscription of the UE (330, 700).

16. A method for providing beam management procedure status indication to a network node (310, 600), wherein the method is performed by a user equipment, UE (330, 700), and wherein the method comprises: performing (S202) a measurement on a downlink reference signal as having been transmitted by the network node (310, 600) in a set of beams (340); performing (S204) an initial access procedure with the network node (310, 600), where, as part of performing the initial access procedure, the UE (330, 700) sends an indication of a beam (360c) in the set of beams (340); sending (S206) a status indication of the UE (330, 700) to the network node (310, 600) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of a beam management procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and performing (S208) a communication procedure with the network node (310, 600), wherein which communication procedure to be performed is dependent on the sent status indication.

17. The method according to claim 16, wherein each of the beams (360a:360c) in the set of beams (340) has a respective beam index that is transmitted together with the downlink reference signal, and wherein the indication sent from the UE (330, 700) of said beam (360c) in the set of beams (340) is the beam index of said beam (360c) in the set of beams (340).

18. The method according to claim 16 or 17, wherein the measurement is performed as part of the UE (330, 700) participating in said at least part of the beam management procedure.

19. A network node (310, 600) for receiving beam management procedure status indication from a user equipment, UE (330, 700), the network node (310, 600) comprising processing circuitry (610), the processing circuitry being configured to cause the network node (310, 600) to: transmit, as part of performing a beam management procedure, a downlink reference signal in a set of beams (340); perform an initial access procedure with the UE (330, 700), where, as part of performing the initial access procedure, the network node (310, 600) receives an indication from the UE (330, 700) of a beam (360c) in the set of beams (340); receive a status indication from the UE (330, 700) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of the beammanagement procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and perform a communication procedure with the UE (330, 700), wherein which communication procedure to be performed is dependent on the received status indication.

20. The network node (310, 600) according to claim 19, further being configured to perform the method according to any of claims 2 to 15.21 . A user equipment, UE (330, 700), for providing beam management procedure status indication to a network node (310, 600), the UE (330, 700) comprising processing circuitry (710), the processing circuitry being configured to cause the UE (330, 700) to: perform a measurement on a downlink reference signal as having been transmitted by the network node (310, 600) in a set of beams (340); perform an initial access procedure with the network node (310, 600), where, as part of performing the initial access procedure, the UE (330, 700) sends an indication of a beam (360c) in the set of beams (340); send a status indication of the UE (330, 700) to the network node (310, 600) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of a beam management procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and perform a communication procedure with the network node (310, 600), wherein which communication procedure to be performed is dependent on the sent status indication.

22. The UE (330, 700) according to claim 21, further being configured to perform the method according to any of claims 17 to 18.

23. A computer program (820a) for receiving beam management procedure status indication from a user equipment, UE (330, 700), the computer program comprising computer code which, when run on processing circuitry (610) of a network node (310, 600), causes the network node (310, 600) to: transmit (S102), as part of performing a beam management procedure, a downlink reference signal in a set of beams (340);perform (S104) an initial access procedure with the UE (330, 700), where, as part of performing the initial access procedure, the network node (310, 600) receives an indication from the UE (330, 700) of a beam (360c) in the set of beams (340); receive (S106) a status indication from the UE (330, 700) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of the beam management procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and perform (S108) a communication procedure with the UE (330, 700), wherein which communication procedure to be performed is dependent on the received status indication.

24. A computer program (820b) for providing beam management procedure status indication to a network node (310, 600), the computer program comprising computer code which, when run on processing circuitry (710) of a user equipment, UE (330, 700), causes the UE (330, 700) to: perform (S202) a measurement on a downlink reference signal as having been transmitted by the network node (310, 600) in a set of beams (340); perform (S204) an initial access procedure with the network node (310, 600), where, as part of performing the initial access procedure, the UE (330, 700) sends an indication of a beam (360c) in the set of beams (340); send (S206) a status indication of the UE (330, 700) to the network node (310, 600) during the initial access procedure, wherein the status indication specifies at least one of: whether the UE (330, 700) has participated in at least part of a beam management procedure or not, whether the indication of said beam (360c) was of a beam in the set of beams (340) for which the downlink reference signal was received with highest received power by the UE (330, 700) or not; and perform (S208) a communication procedure with the network node (310, 600), wherein which communication procedure to be performed is dependent on the sent status indication.

25. A computer program product (810a, 810b) comprising a computer program (820a, 820b) according to at least one of claims 23 and 24, and a computer readable storage medium (830) on which the computer program is stored.

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