Mobility management method

Abstract

The invention relates to a computer-implemented method (800) for performing mobility measurements in a radio network (100), the method being performed by a user equipment, UE (110), in the radio network (100), the UE (110) being configured for multiple transmission and reception point operation the method comprising: receiving mobility measurement configuration (610) from a network node (N1) in the radio network, the mobility measurement configuration (610) being indicative of rules for selecting a set of TRP candidates for which the UE (110) should acquire downlink synchronization, performing mobility measurements on TRP candidates in accordance with the measurement configuration, acquiring downlink synchronization for a first set of TRP candidates (TRP1, TRP3, TRP4) selected based on the rules and the mobility measurements, transmitting a mobility measurement report (620) to the node, the report indicating the downlink synchronized set of TRP candidates.

Description

[0001] MOBILITY MANAGEMENT METHOD

[0002] TECHNICAL FIELD

[0003] The present invention relates to mobility management for user equipment configured for multiple transmission and reception point (TRP) operation.

[0004] BACKGROUND

[0005] In a radio network, user equipment (UE) typically moves around geographically, or the surrounding radio environment conditions change, and it is of utmost importance to connect via suitable access points.

[0006] In current New Radio, NR, the access technology is evolving to support UE multi-Transmission Reception Point (mTRP) connectivity including L1 / L2 triggered mobility (LTM). The traditional concept of a Cell associated to a single TRP is changing, and the cell is becoming more a logical concept, where a Cell is potentially associated to multiple TRP’s. A node and associated cell can manage resources of one or more TRP’s per UE connection. The TRP’s are typically spatially separated on different geographical antenna positions often on the same frequency layer. Key aspects of future mobility management solutions are resource- and signalingefficiency for interruption free and fast change of allocated dedicated resources.

[0007] A problem with conventional solutions is that theoretical best TRP candidates in downlink, DL, and best theoretical TRP candidates in uplink, UL, will vary over time and may not be the same in DL and UL. As the UE must wait until explicitly instructed by the network (NW) to perform a synchronization effort for one or more TRPs, this has the drawback of extra battery consumption and time delays when changing TRPs.

[0008] Thus, there is a need for an improved mobility management method for enhancing radio network performance.

[0009] An object of the invention is to address the above-mentioned shortcomings of conventional solutions.

[0010] SUMMARY OF THE INVENTION

[0011] The above-described drawbacks are overcome by the subject matter described herein. Further advantageous implementation forms of the invention are described herein. The invention is set out in the appended set of claims.

[0012] According to a first aspect the objects of the invention are achieved by a computer- implemented method for performing mobility measurements in a radio network, the method being performed by a user equipment, UE, in the radio network, the UE being configured for multiple transmission and reception point, TRP, operation the method comprising: receiving mobility measurement configuration from a network node in the radio network, the mobility measurement configuration being indicative of rules for selecting a set of TRP candidates for which the UE should acquire downlink synchronization, performing mobility measurements on TRP candidates in accordance with the mobility measurement configuration, acquiring downlink synchronization for a first set of TRP candidates selected based on the rules and the mobility measurements, transmitting a mobility measurement report to the network node, the report indicating the downlink synchronized first set of TRP candidates.

[0013] In one embodiment according to the first aspect, mobility measurements are performed for a second set of TRP candidates, and wherein the first set of TRP candidates is selected from the second set.

[0014] In one embodiment according to the first aspect, the method further comprises: determining timing information for the TRP candidates of the first set of TRP candidates, wherein the transmitted mobility measurement report further comprises the determined timing information.

[0015] In one embodiment according to the first aspect, determining timing information comprises measuring reception timing difference between TRP candidates of the first set of TRP candidates.

[0016] In one embodiment according to the first aspect, selecting the first set of TRP candidates comprises at least one of adding one or more TRP candidates of the second set to the first set of TRP candidates and removing one or more TRP candidates from the first set of TRP candidates.

[0017] In one embodiment according to the first aspect, the steps of performing mobility measurements and acquiring downlink synchronization is performed for a plurality of frequency layers, wherein the mobility measurement report comprises a set of TRP candidates for each frequency layer.

[0018] In one embodiment according to the first aspect, the method further comprises receiving a TRP change command from the network node, the change command indicating a change to one of the TRPs from the first set of TRP candidates, and changing serving TRP according to the TRP change command. According to a second aspect the objects of the invention are achieved by a user equipment, UE, of a radio network (100), the UE comprising: a processor, and a memory, said memory containing instructions executable by said processor, whereby said UE is operative to perform the method according to the first aspect.

[0019] According to a third aspect the objects of the invention are achieved by a computer- implemented method for configuring a user equipment, UE, to perform mobility measurements configuration in a radio network, the UE being configured for multiple transmission and reception point, TRP, operation, the method being performed by a network node in the radio network, the method comprising: transmitting mobility measurement configuration to the UE, the mobility measurement configuration being indicative of rules for selecting TRP candidates for which the UE should acquire downlink synchronization, receiving a mobility measurement report from the UE in accordance with the mobility measurement configuration, the report indicating a set of TRP candidates for which the UE has acquired downlink synchronization.

[0020] In one embodiment according to the second aspect, the method further comprises determining one TRP candidate of the indicated set of TRP candidates to change to, and transmitting a TRP change command to the UE indicating a change to the determined TRP candidate.

[0021] In one embodiment according to the second aspect the method further comprises: preparing an associated node of the one TRP candidate for a change by the UE by communicating with the associated nodes.

[0022] In one embodiment according to the second aspect, the mobility measurement report further comprises timing information for each of the TRP candidates of the set of TRP candidates, wherein TRP change command further comprises Timing Advance, TA, information determined based on the timing information.

[0023] According to a fourth aspect the objects of the invention are achieved by a network node in a radio network, the node comprises a processor, and a memory, said memory containing instructions executable by said processor, whereby said node is operative to perform the method according to the third aspect.

[0024] The scope of the invention is defined by the claims, which are incorporated into this section by reference. Reference will be made to the appended sheets of drawings that will first be described briefly.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A more complete understanding of embodiments of the invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.

[0027] Fig. 1 shows an example of a radio network according to one or more embodiments of the present disclosure.

[0028] Fig. 2A illustrates an example of a UE performing mobility measurements according to one or more embodiments of the present disclosure.

[0029] Fig. 2B illustrates an example of a UE acquiring downlink synchronization for a set of TRP candidates according to one or more embodiments of the present disclosure.

[0030] Fig. 3A-B illustrates addition of a TRP to the set according to one or more embodiments of the present disclosure.

[0031] Fig. 4A-B illustrates removal of a TRP to the set according to one or more embodiments of the present disclosure.

[0032] Fig. 5A-D illustrates replacement TRPs in the set according to one or more embodiments of the present disclosure.

[0033] Fig. 6 shows a signaling chart according to one or more embodiments of the present disclosure.

[0034] Fig. 7 shows an example of signaling chart when the network alone decides the set of TRPs according to prior art.

[0035] Fig. 8 shows a flowchart of a method according to one or more embodiments of the present disclosure.

[0036] Fig. 9 shows a flowchart of a method according to one or more embodiments of the present disclosure.

[0037] Fig. 10 shows details of a radio network node according to one or more embodiments of the present disclosure.

[0038] Fig. 11 illustrates a UE comprising functional modules according to one or more embodiments of the present disclosure.

[0039] Fig. 12 illustrates a network node N1 comprising functional modules according to one or more embodiments of the present disclosure. A more complete understanding of embodiments of the invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.

[0040] DETAILED DESCRIPTION

[0041] The present disclosure relates to improving radio network performance. In particular, this relates to improving mobility management of User Equipment, UE.

[0042] The task for mobility management solutions is to always use the most relevant resources in DL and in UL, and thus be able to change resources and associated Transmission and Reception Points, TRP, used for the UE connection, as fast and seamless as possible.

[0043] NW configured UE measurement configuration and measurement reporting control have been introduced by 3rd Generation Partnership Project, 3GPP, since second generation, 2G, and further enhanced by introducing UE evaluated event and associated rules in 3G and continued in fourth generation, 4G and fifth generation, 5G.

[0044] The overall ambition is to, with a minimum of network, NW / UE signaling, allow each UE to use the most relevant resources, and respective associated TRP’s at all times. Resources can be configured for immediate use or pre-configured and later activated by NW or UE for maintaining UE connections. When the UE measures and monitors many TRP candidates, the downlink, DL, synchronization accuracy may be less accurate as compared to when using downlink, DL, and uplink, UL resources from a single TRP. This implies that the UE need to do an extra synchronization refinement effort and some reference symbol detections before using DL and UL resources, to ensure that sufficient synchronization accuracy is achieved.

[0045] The extra DL synchronization efforts is in this description sometimes referred to as “Pre-synch” or “Early synch”. In one non-limiting example, this involves comparing how a currently assigned timing advance, TA, value matches, uplink slots reception of UE transmission of a candidate TRP.

[0046] A drawback with conventional solutions is that there is a delay in responding to rapidly varying radio conditions, as best candidates in DL and best candidates in UL will vary over time and may not be the same in DL and UL. The conventional method is to select candidates by the NW and signal this selection to the UE to perform synchronization efforts, “Pre-synch” or “Early synch”. The required signaling introduces delays. These delays means that conditions for the UE likely changes, and that a TRP candidate selected by the NW, the UE may no longer be able to acquire synchronization for that candidate. In other words, the synchronization effort will fail. Furthermore, to mitigate the risk for failure the NW may select and prepare many TRP’s which imply an extra NW resource cost and an extra UE effort when trying to acquire presynch.

[0047] Fig. 7 shows an example of signaling chart when the NW alone decides the set of TRPs to perform. In other words, this is a conventional method.

[0048] Fig. 7 shows a UE currently connected to a source node N1 and having a target node N2 with an associated TRP in the environment of the UE. E.g., like the scenario shown in Fig 3A-B.

[0049] The UE 110 receives a signal 1 (RRC Reconfiguration) indicative of a mobility measurement configuration from the node N1 in the radio network 100.

[0050] Optionally, the UE sends a signal (RRC Reconfiguration complete) comprising a confirmation that the mobility measurement configuration has been received to the source node N1 .

[0051] The UE then performs mobility measurements on TRP candidates in accordance with the measurement configuration. This is further described in relation to Fig. 2A.

[0052] The UE then transmits a signal comprising a mobility measurement report 2 to the node, the report indicating signal characteristics of the measured TRPs.

[0053] The source node N1 then prepares TRP candidates by selecting a set of TRPs based on the reported signal characteristics of the measured TRPs, e.g., signal strength and SINR.

[0054] Optionally, the source node N1 then sends a signal 4 to the UE comprising an updated mobility measurement configuration (RRC Reconfiguration), typically indicative of the set of TRPs selected by the node N1.

[0055] Optionally, the UE sends a signal (RRC Reconfiguration complete) indicating that the set of TRPs selected by the node N1 has been received to the source node N1 .

[0056] Optionally, the UE then performs mobility measurements on TRP candidates and attempts to perform synchronization efforts / pre-synch on the set of TRPs selected by the node N1 in accordance with the updated measurement configuration. As the radio environment may have changed, synchronization efforts / pre-synch may fail for some TRP candidates.

[0057] Optionally, the UE then transmits a signal comprising an updated mobility measurement report (MAC / L1 Measurement Report) to the node N1 , the report indicating signal characteristics of the measured TRPs. Optionally, the source node N1 then makes a decision to change TRPs connected to the UE and sends a signal to the UE comprising a TRP change decision 8 (MAC / L1 TRP change command).

[0058] Optionally, the UE performs a TRP change 9 and connects to TRPs according to the TRP change decision 650. Connecting to the TRPs according to the TRP change decision 650 may comprise performing random access transmissions.

[0059] Optionally, the UE then performs mobility measurements on TRP candidates and attempts to perform synchronization efforts / pre-synch on any TRP of the set of TRPs selected by the node N1 . The UE may further perform UL random access.

[0060] The procedure for the TRP change 12 is then completed.

[0061] In other words, Fig. 7 illustrates the following:

[0062] 1 . Measurement configuration according to legacy.

[0063] 2. Measurement report according to legacy.

[0064] 3. Source and optionally target node, e.g., gNB, prepare NW resources for support of new configuration and how to use TRP's.

[0065] 4. UE receives information from node N1 , e.g., gNB, on how to prepare itself for use of candidate TRP’s.

[0066] 5. UE do DL pre-synch efforts which may take significant amount of time or in worst case fail on the candidates as indicated by node N1 , e.g., gNB, and start sending MAC / L1 measurement reports periodically.

[0067] 6. UE sends MAC / L1 a measurement report which fulfills source nodes criteria for initiating resource changes (adding / removing / replacing TRP's).

[0068] 7. Source node N1 decides resource changes by adding / removing TRP from usage and the manner of how to do the changes (e.g., with or without Random access) based on the MAC / L1 report.

[0069] 8. Source node N1 commands the UE to do resource change according to candidate preparation and source node N1 change decisions.

[0070] 9. UE executes the resource change.

[0071] 10. Optionally the UE sends random access if the node N1 have instructed the UE to do so in 7.

[0072] 11 . Data can continue to be transferred in DL and UL using the changed resources. 12. UE and source node N1 and target node N2 complete the resource change actions e.g., releasing old resources and continue using the new resources

[0073] Part of the present disclosure is the realization that if the UE is not allowed to influence the selection of TRP candidates to acquire synchronization for, then battery / energy resources for the UE are wasted. More precisely, if no rules are provided to UE by which the UE can select TRP’s that are relevant candidates to acquire pre-synch on, then the UE need to do that synchronization effort for all possible candidates detected. Alternatively, the UE must wait to be explicitly instructed to synchronize by the NW. As mentioned, this increases battery consumption and introduces time delays.

[0074] When the NW alone selects which TRP’s that are relevant candidates to acquire pre-synch on, this has the drawback of requiring very frequent signaling from NW to UEs or selecting and preparing many TRP’s in a speculative manner when the UE moves, and also introduce delay’s for pre-synch acquisition when changing resources.

[0075] The present disclose provides a solution that allows the UE to select and update a set of TRP’s that need periodic pre-synch / synchronization efforts, either with or without configured NW rules. This has the advantage that when there is a need for resource change, the DL synchronization accuracy will already be ok for some TRP candidates, and the status of the pre-synch / synchronization efforts is included in the measurement report. In other words, less delay is introduced and less TRP’s need to be prepared before DL and UL transmissions are performed on resources associated with new TRPs (not currently connected to the UE) as the UE and TRP have sufficient synchronization accuracy.

[0076] Since performing synchronization efforts / pre-synch also allows timing information to be measured from TRP’s, the measurement report can optionally include this timing information to be used by the NW. The NW may use this timing information for e.g., for determining if timing advance adjustment e.g. ,via Random access is needed or not before TRP can be used in UL i.e., determining if TRP UL reception will be within UL reception window or not .

[0077] The timing information can e.g., be by the UE received difference in time between signals from measured and pre-synched TRPs' (including the currently used / connected TRPs). Optionally the timing information may further include round trip time measurements from TRP's that the UE is connected to.

[0078] A change of TRP’s used in the NW to UE connection, can either be triggered directly based on NW signaling or be based on UE triggered Conditions that NW have prepared the UE for in advance, i.e., a “Conditional Handover / setup” concept. In brief, the present disclosure provides a solution where the UE use rules on how and when the UE should update a set of TRP’s for which pre-synch is maintained for (i.e., for which synchronization accuracy of a certain level is maintained). The UE may select TRP’s by adding / removing / replacing TRP’s to a set for which pre-synch is maintained. This is typically performed by detecting, identifying, and monitoring TRP candidates in the environment of the UE.

[0079] As the TRPs in the maintained set have sufficient synchronization accuracy, the UE may transmit on UL without additional pre-synch efforts. E.g., when trigger conditions are fulfilled or when NW order the UE to do so.

[0080] The advantages of the present disclosure are at least that each UE can maintain pre-synch efforts for a limited amount of TRPs and by that gain higher accuracy without using more battery power. A further advantage is that the UE is ready to transmit on UL and use DL directly (without delay) with TRPs in the maintained set. A further advantage is that signaling is reduced, as the NW and UE signaling effort will not increase exponentially with the amount of UE’s , UE speed , TRP coverage variations and number of potential TRPs for which pre-synch is maintained for. The UE pre-synch effort can also be reduced by the NW by configuring a smaller “max number” of TRP’s” in the rules that the measurement configuration is based upon. Further NW resource availability can be increased and associated requirements for fast response and no interruption can be achieved and made UE and service usage dependent.

[0081] In the present disclosure, the term “change command” denotes instructions to a UE regarding which TRPs to be connected to.

[0082] In the present disclosure, the term “change decision” denotes the procedure to identify the TRPs to be connected to in the change command. In other words, it is the decision made by the network node about which TRP / s to change to or connect to, which decision the UE then is informed about in the change command described above.

[0083] Fig. 1 shows an example of a radio network 100 according to one or more embodiments of the present disclosure. The radio network 100 comprises a plurality of Nodes N1-N3 controlling TRPs TRP1-TRP9 configured to receive / transmit radio signals from / to UEs 110 in the radio network 100. Each node N1-N3 and / or TRP TRP1-TRP9 comprises one or more antennas and circuitry capable of performing radio reception / transmission.

[0084] In Fig. 1 , the radio access nodes N1-N3 may offer different radio access technologies.

[0085] In one example, the radio network 100 is a New Radio, NR, network supporting UE multiTransmission Reception Point (mTRP) connectivity including L1 / L2 triggered mobility (LTM) or a future 6G radio network. Each node N1-N3 comprises one or more cells C1-C3 that are each associated to multiple TRP’s. Cell C1 is associated with TRP1-3, cell C2 is associated with TRP 4-6 and cell C3 is associated with TRP7-9.

[0086] A cell C1-C3 can manage resources of one or more TRP’s per UE connection. More than one cell and / or node may be involved in the UE connection. I.e., mTRP connectivity. The TRP’s are typically spatially separated on different geographical antenna positions often on the same frequency layer.

[0087] Fig. 2A illustrates an example of a UE performing mobility measurements according to one or more embodiments of the preset disclosure.

[0088] The UE initially receives a mobility measurement configuration, e.g., from a connected node N1. The mobility measurement configuration is indicative of rules for selecting a set of TRP candidates, e.g., how many candidates, for which the UE 110 should acquire downlink synchronization.

[0089] Optionally, the measurement configuration is further indicative of a “baseline set”, for which synchronization efforts / pre-synch should be performed. The baseline set may comprise TRP1 , TRP6 and TRP8.

[0090] The UE then detects, identifies and monitors TRP candidates in the environment of the UE. In the example shown in Fig. 2A this is performed for TRP1 , TRP3, TRP4, TRP6, TRP7 and TRP8. In other words, the UE performs mobility measurements on TRP candidates in accordance with the measurement configuration.

[0091] The UE measures DL signal characteristics of the TRPs, e.g., timing information and / or signal strength and / or pathloss and / or signal-to-interference-plus-noise ratio, SINR, SS-Pathgain, SS-Pathloss, SS-RSRP, SS-RSRQ, SS-SINR, CSI-RSRP, CSI-SINR.

[0092] Fig. 2B illustrates an example of a UE acquiring downlink synchronization for a set of TRP candidates TRP1 , TRP3, TRP4 according to one or more embodiments of the present disclosure. In Fig. 2B, a maximum of three candidates are shown. However, any suitable number of candidates may be used.

[0093] After performing mobility measurements on TRP candidates TRP1 , TRP3, TRP4, TRP6, TRP7, the signal characteristics may be ranked or ordered, e.g., by identifying a Top-K list. In other words, by identifying the K TRPs having the best characteristics and ordering them from best to worst. The UE may in one example identify a set of TRP candidates TRP1 , TRP3, TRP4, e.g., three candidates, that are most suitable for maintaining a connection to the UE based on the rules of the measurement configuration and the mobility measurements.

[0094] Optionally, the UE starts with the baseline set TRP1 , TRP6 and TRP8, removes TRP6 and TRP8, and adds TRP3, TRP4.

[0095] The UE then acquires downlink synchronization (performs synchronization efforts / pre-synch) for the set of TRP candidates TRP1 , TRP3, TRP4.

[0096] In one example, acquiring downlink synchronization further includes determining synchronization accuracy, which is indicative of a reception timing of signals from the set of TRP candidates TRP1 , TRP3, TRP4.

[0097] The UE then transmits a mobility measurement report to the node N1 , the report indicating the downlink synchronized set of TRP candidates TRP1 , TRP3, TRP4 and optionally also timing information. In other words, indicating synchronization status and / or timing information.

[0098] As mentioned previously, timing information can be by the UE received difference in time between signals from measured and pre-synched TRPs' (including currently used), and optionally round-trip time measurements from TRP's that the UE is connected to.

[0099] Fig. 3A-B illustrates addition of a TRP to the set according to one or more embodiments of the present disclosure.

[0100] In Fig. 3A, the set for which synchronization efforts / pre-synch is to be performed for, initially comprises TRP1 and TRP3.

[0101] Based on the rules of the measurement configuration and the mobility measurements, TRP4 is added to the set.

[0102] In Fig. 3B, the set for which synchronization efforts / pre-synch is to be performed is shown, and now comprises TRP1 , TRP3 and TRP4.

[0103] Fig. 4A-B illustrates removal of a TRP to the set according to one or more embodiments of the present disclosure.

[0104] In Fig. 4A, the set for which synchronization efforts / pre-synch is to be performed for, initially comprises TRP1 , TRP3 and TRP4.

[0105] Based on the rules of the measurement configuration and the mobility measurements, TRP4 is removed from the set.

[0106] In Fig. 4B, the set for which synchronization efforts / pre-synch is to be performed is shown, and now comprises TRP1 and TRP3. Fig. 5A-B illustrates replacement TRPs in the set according to one or more embodiments of the present disclosure.

[0107] In Fig. 5A, the set for which synchronization efforts / pre-synch is to be performed for, initially comprises TRP1 and TRP3 of cell C1 .

[0108] Based on the rules of the measurement configuration and the mobility measurements, TRP1 and TRP3 are removed from the set, and TRP4 and TRP6 of cell C2 are added to the set.

[0109] This may be needed if TRP relations between Cell 1 and Cell 2 does not allow MTRP usage between TRP’s belonging to different cells.

[0110] In Fig. 5B, the set for which synchronization efforts / pre-synch is to be performed is shown, and now comprises TRP4 and TRP6 of cell C2.

[0111] It is understood that the add, remove, replace operations may be performed on TRPs associated to the same node / cell and / or TRPs associated to different nodes / cells without departing from the present disclosure.

[0112] In Fig. 5C, the set for which synchronization efforts / pre-synch is to be performed for, initially comprises TRP1 and TRP3 of cell C1 , and further TRP4 of cell C2.

[0113] Based on the rules of the measurement configuration and the mobility measurements, TRP4 is removed from the set, and TRP6 of cell C2 is added to the set.

[0114] This may be needed if TRP relations between Cell 1 and Cell 2 does not allow MTRP usage between TRP’s belonging to different cells.

[0115] In Fig. 5D, the set for which synchronization efforts / pre-synch is to be performed is shown, and now comprises TRP1 and TRP3 of cell C1 , and further TRP4 of cell C2.

[0116] It is understood that the add, remove, replace operations may be performed on TRPs associated to the same node / cell and / or TRPs associated to different nodes / cells without departing from the present disclosure.

[0117] Fig. 6 shows a signaling chart according to one or more embodiments of the present disclosure.

[0118] Steps performed by the UE is further described in relation to Fig. 8. Steps performed by the network node is further described in relation to Fig. 9.

[0119] Fig. 6 shows a UE currently connected to a source node N1 and having a target node N2 with an associated candidate TRP in the environment of the UE. E.g., like the scenario shown in Fig 3A-B. The UE 110 receives a signal indicative of a mobility measurement configuration 610 from the network node N1 in the radio network 100. The mobility measurement configuration 610 is indicative of rules for selecting a set of TRP candidates for which the UE 110 should acquire downlink synchronization. In one example, the rules indicate that up to three TRPs should be included in the set based on best received signal strength and / or SINR.

[0120] Optionally, the UE sends a signal comprising a confirmation that the mobility measurement configuration 610 has been received to the source node N1.

[0121] The UE then performs mobility measurements on TRP candidates in accordance with the measurement configuration. This is further described in relation to Fig. 2A.

[0122] The UE maintains / selects the set of TRPs for which synchronization efforts / pre-synch should be performed based on the rules of the mobility measurement configuration 610.

[0123] An example of how the UE may maintains / selects the set is provided below and is illustrated in relation to Fig. 2B. In this example, there are three TRPs and that any of these TRPs either in isolation or in combination with one or two other TRPs is a member of the set. At the outset, a performance metric is highest for TRP1 and lowest for TRP3. Further, neither TRP 4 nor TRP 4 has a performance metric that qualifies these two TRPs to be part of the set. Hence, at the outset, the set consists of TRP1 . A selection range may be used and has a fixed offset with respect to the currently best performance metric of the measured TRPs. Any TRP having a performance metric within the selection range is to be considered for inclusion selection into the set. Further, the performance metric needs to be better than an entering threshold value (defined as range ± hysteresis) during the duration of a timer to be selected. Further, for a TRP to leave the set, the performance metric needs to be lower than a leaving threshold value (defined as reporting range ± hysteresis) during the duration of a timer. The performance metric for TRP 1 may reach a peak and decline whereas the performance metric for TRP 3 may increase and eventually become better than the entering threshold value longer than the timer duration. This causes TRP2 to also be included in the set. Further, the performance metric for TRP3 may even become better than the performance metric for TRP1 which will mean that TRP3 is the best TRP and used by UE as reference for reporting range. Eventually, also a performance metric for TRP4 may become better than the entering threshold value longer than the timer duration. This causes TRP4 to also be included in the set. Eventually, the performance metric for TRP1 becomes so low that it will be lower than the leaving threshold value longer than timer duration. This will cause TRP1 to be removed from the active TRP measurement set. The performance metric is typically applied to signal characteristics measured by the UE, as described in relation to Fig. 2A. The UE then acquires downlink synchronization for the set of TRP candidates TRP1 , TRP3, TRP4 that was selected based on the rules and the mobility measurements. As mentioned previously, this typically involves performing synchronization efforts / pre-synch.

[0124] The UE then transmits a signal comprising a mobility measurement report 620 to the node, the report indicating at least the downlink synchronized set of TRP candidates. Optionally, the report also comprises timing information.

[0125] There could be different criteria for when the UE is to provide the measurement reporting to the network node N1. In particular, in some embodiments, the UE 110 further is configured by the network node N1 to only provide the measurement reporting when the first active TRP measurement set fulfils a measurement report triggering condition. The first report triggering condition is selected from a set of events. Non-limiting examples of such events are:

[0126] Event 1 : A detected TRP enters Reporting Range,

[0127] Event 2: An active TRP leaves Reporting Range,

[0128] Event 3: A detected TRP leaves Reporting Range,

[0129] Event 4: A detected TRP becomes better than an active TRP,

[0130] Event 5: Change of best active TRP,

[0131] Event 7: An active TRP becomes worse than an absolute threshold,

[0132] Event 8: An active TRP becomes better than an absolute threshold,

[0133] Event 9: Change of best TRP (active or detected),

[0134] Event 10: A TRP becomes worse than an absolute threshold, and

[0135] Event 11 : A TRP becomes better than an absolute threshold.

[0136] These are all just some examples of events.

[0137] The source node N1 then prepares TRP candidates in the mobility measurement report 620 by communicating with associated nodes of TRPs in the set of TRPs to ensure that resources are available to the UE and that the UE can be connected to the respective indicated TRP. Note that some TRP may be used in DL only and some in UL only and some both in DL and UL.

[0138] Optionally, the source node N1 then performs a TRP change decision to change TRPs connected to the UE and transmits a TRP change command 630 to the UE comprising the TRP change decision. Optionally, the UE received the TRP change command 630 and executes a TRP change and connects to TRPs according to the TRP change decision. Connecting to the TRPs according to the TRP change decision 650 may comprise performing random access transmissions.

[0139] Fig. 8 shows a flowchart of a method 800 according to one or more embodiments of the present disclosure. The method may be a computer-implemented method 800 for performing mobility measurements in a radio network 100. The method is performed by a user equipment, UE 110, in the radio network 100. The UE 110 is configured for multiple transmission and reception point operation the method comprising:

[0140] Step 810: receiving mobility measurement configuration 610 from a network node N1 in the radio network, the mobility measurement configuration 610 being indicative of rules for selecting a set of TRP candidates for which the UE 110 should acquire downlink synchronization.

[0141] Step 820: performing mobility measurements on TRP candidates in accordance with the measurement configuration.

[0142] Step 830: acquiring downlink synchronization for a first set of TRP candidates TRP1 , TRP3, TRP4 selected based on the rules and the mobility measurements.

[0143] Step 840: transmitting a mobility measurement report 620 to the node, the report indicating the downlink synchronized first set of TRP candidates.

[0144] Additionally, or alternatively, mobility measurements are performed for a second set of TRP candidates TRP1 , TRP3, TRP4, TRP6, TRP7, TRP8, and wherein the first set of TRP candidates TRP1 , TRP3, TRP4 is selected from the second set.

[0145] Additionally, or alternatively, the method further comprises determining timing information for the TRP candidates of the first set of TRP candidates, wherein the transmitted mobility measurement report further comprises the determined timing information.

[0146] Additionally, or alternatively, determining timing information comprises measuring reception timing difference between TRP candidates of the first set of TRP candidates.

[0147] Additionally, or alternatively, selecting the first set of TRP candidates comprises at least one of adding one or more TRP candidates of the second set to the first set of TRP candidates and removing one or more TRP candidates from the first set of TRP candidates.

[0148] Additionally, or alternatively, the steps of performing mobility measurements and acquiring downlink synchronization is performed for a plurality of frequency layers, wherein the mobility measurement report 620 comprises a set of TRP candidates for each frequency layer. Additionally, or alternatively, the method further comprises receiving 850 a TRP change command from the network node N1 , the change command indicating a change to one of the TRPs from the first set of TRP candidates and changing serving TRP according to the TRP change command. In one embodiment, the TRP change command comprises updated timing advance, TA, values.

[0149] Fig. 9 shows a flowchart of a method 900 according to one or more embodiments of the present disclosure. The method is a computer-implemented method for configuring a user equipment, UE, 110, to perform mobility measurements configuration in a radio network 100. The UE is configured for multiple transmission and reception point operation. The method is performed by a node N1 , N2 in the radio network. The method comprises:

[0150] Step 910: transmitting mobility measurement configuration 610 of the UE 110, the mobility measurement configuration 610 being indicative of rules for selecting TRP candidates for which the UE should acquire downlink synchronization.

[0151] Step 920: receiving a mobility measurement report 620 from the UE 110 in accordance with the mobility measurement configuration 610, the report 620 indicating TRP candidates TRP1 , TRP3, TRP4 for which the UE 110 has acquired downlink synchronization.

[0152] Additionally, or alternatively, the method further comprises determining 930 one TRP candidate of the indicated set of TRP candidates TRP1 , TRP3, TRP4 to change to, and transmitting 940 a TRP change command 630 to the UE indicating a change to the determined TRP candidate.

[0153] Additionally, or alternatively, the method further comprises preparing an associated node of the one TRP candidate for a change by the UE by communicating with the associated nodes.

[0154] Additionally, or alternatively, the mobility measurement report 620 further comprises timing information for each of the TRP candidates of the set of TRP candidates. In one embodiment, the TRP change command further comprises Timing Advance, TA, information determined based on the timing information.

[0155] Fig. 10 shows details of a radio network node 1000 according to one or more embodiments of the present disclosure.

[0156] The network node 1000 may be in the form of a selection of any of a gNB, a virtual node in a cloud, a network node, a desktop computer, server, laptop, mobile device, a smartphone, a tablet computer, a smart watch etc. The network node 1000 may comprise processing circuitry 1012. The network node 1000 may optionally comprise or be communicatively coupled to a communications interface 1004 for wired and / or wireless communication. Further, the network node 1000 may further comprise at least one optional antenna (not shown in figure). The antenna may be coupled to a transceiver of the communications interface 1004 and is configured to transmit and / or emit and / or receive wireless signals, e.g., in a wireless communication system.

[0157] In one example, the processing circuitry 1012 may be any of a selection of processor and / or a central processing unit and / or processor modules and / or multiple processors configured to cooperate with each-other. Further, the network node 1000 may further comprise a memory 1015. The memory 1015 may contain instructions executable by the processing circuitry 1012, that when executed causes the processing circuitry 1012 to perform any of the methods and / or method steps described herein.

[0158] The communications interface 1004, e.g., the wireless transceiver and / or a wired / wireless communications network adapter is configured to send and / or receive data values or parameters as a signal. In an embodiment, the communications interface 1004 communicates directly between nodes or via a communications network.

[0159] In one or more embodiments the network node ,1000 may further comprise an input device or interface 1017, configured to receive input or indications from a user and output / send a userinput signal indicative of the user input or indications to the processing circuitry 1012. In other words, the input device / interface 1017 receives input or indications from the user and translates this into data that the processing circuitry 1012 can interpret.

[0160] In one or more embodiments the network node 1000 may further comprise a display 1018 configured to receive a display signal indicative of rendered objects, such as text or graphical user input objects, from the processing circuitry 1012 and to display the received signal as objects, such as text or graphical user input objects. In other words, the display receives data that the processing circuitry 1012 can interpret and display the data in a format that the user can understand.

[0161] In one embodiment the display 1018 is integrated with the user input device / interface 1017 and is configured to receive a display signal indicative of rendered objects, such as text or graphical user input objects, from the processing circuitry 1012 and to display the received signal as objects, such as text or graphical user input objects, and / or configured to receive input or indications from a user and send a user-input signal indicative of the user input or indications to the processing circuitry 1012.

[0162] In one or more embodiments the network node 1000 may further comprise one or more additional sensors (not shown). In embodiments, the processing circuitry 1012 is communicatively coupled to the memory 1015 and / or the communications interface 1004 and / or the input device 1017 and / or the display 1018.

[0163] In embodiments, the communications interface and / or transceiver 1004 communicates using wired and / or wireless communication techniques.

[0164] In embodiments, the one or more memory 1015 may comprise a selection of a hard RAM, disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a CD or DVD drive (R or RW), or other removable or fixed media drive.

[0165] In a further embodiment, the network node 1000 may further comprise and / or be coupled to one or more additional sensors (not shown) configured to receive and / or obtain and / or measure physical properties pertaining to the network node or the environment of the network node and send one or more sensor signals indicative of the physical properties to the processing circuitry 1012.

[0166] It is to be understood that a network node comprises any suitable combination of hardware and / or software needed to perform the tasks, features, functions, and methods disclosed herein. Moreover, while the components of the network node are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, a network node may comprise multiple different physical components that make up a single illustrated component (e.g., memory 1015 may comprise multiple separate hard drives as well as multiple RAM modules).

[0167] Similarly, the network node 1000 may be composed of multiple physically separate components, which may each have their own respective components.

[0168] The communications interface 1004 may also include multiple sets of various illustrated components for different wireless technologies, such as, for example, Global System for Mobile Communications GSM, Wideband Code-Division Multiple Access, WCDMA, Long- Term Evolution, LTE, New Radio, NR, Wireless Fidelity, Wi-Fi, or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node 1000.

[0169] Processing circuitry 1012 is configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being provided by a network node . These operations performed by processing circuitry 1012 may include processing information obtained by processing circuitry 1012 by, for example, converting the obtained information into other information, comparing the obtained information, or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination.

[0170] Processing circuitry 1012 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1000 components, such as device readable medium, computer ,1000 functionality. For example, processing circuitry 1012 may execute instructions stored in device readable medium 1015 or in memory within processing circuitry 1012. Such functionality may include providing any of the various wireless features, functions, or benefits discussed herein. In some embodiments, processing circuitry 1012 may include a system on a chip.

[0171] In some embodiments, processing circuitry 1012 may include one or more of radio frequency, RF, transceiver circuitry and baseband processing circuitry. In some embodiments, RF transceiver circuitry and baseband processing circuitry may be on separate chips or sets of chips, boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry and baseband processing circuitry may be on the same chip or set of chips, boards, or units.

[0172] In certain embodiments, some or all the functionality described herein as being provided by a network node may be performed by the processing circuitry 1012 executing instructions stored on device readable medium 1015 or memory within processing circuitry 1012. In alternative embodiments, some or all the functionalities may be provided by processing circuitry 1012 without executing instructions stored on a separate or discrete device readable medium, such as in a hard-wired manner. In any of those embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry 1012 can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry 1012 alone or to other components of network node but are enjoyed by network node 1000 and / or by end users.

[0173] Device readable medium or memory 1015 may comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device readable and / or computerexecutable memory devices that store information, data, and / or instructions that may be used by processing circuitry 1012. Device readable medium 1015 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, etc. and / or other instructions capable of being executed by processing circuitry 1012 and, utilized by network node. Device readable medium may be used to store any calculations made by processing circuitry 1012 and / or any data received via interface 1004. In some embodiments, processing circuitry 1012 and device readable medium 1015 may be considered to be integrated.

[0174] The communications interface 1004 is used in the wired or wireless communication of signaling and / or data between network node ,1000, and other nodes. Interface 1004 may comprise port(s) / terminal(s) to send and receive data, for example to and from network node ,1000 over a wired connection. Interface 1004 also includes radio front end circuitry that may be coupled to, or in certain embodiments a part of, an antenna. Radio front end circuitry may comprise filters and amplifiers. Radio front end circuitry may be connected to the antenna and / or processing circuitry 1012.

[0175] Examples of a network node 1000 include, but are not limited to an gNB, a gateway, a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a desktop computer, a personal digital assistant (PDA), a wireless cameras, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer-premise equipment (CPE), a vehicle-mounted wireless terminal device, a drone, an O-CU (O-RAN Central Unit), an O-DU (O-RAN Distributed Unit), an O-RU (O-RAN Radio Unit), a Near-RT RIC (Near Real-Time RAN Intelligent Controller), a Non-RT RIC, SMO (Service Management and Orchestration) etc.

[0176] The communication interface 1004 may encompass wired and / or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. The communication interface may be configured to include a receiver and a transmitter interface used to communicate with one or more other devices over a communication network according to one or more communication protocols, such as Ethernet, TCP / IP, SONET, ATM, optical, electrical, and the like). The transmitter and receiver interface may share circuit components, software, or firmware, or alternatively may be implemented separately.

[0177] In one embodiment, a node N1 , N2 in a radio network 100 is provided, the node comprising: a processor, and a memory, said memory containing instructions executable by said processor, whereby said node N1 , N2 is operative to perform the methods described herein.

[0178] In one embodiment, a UE in a radio network 100 is provided, the UE comprises: a processor, and a memory, said memory containing instructions executable by said processor, whereby said UE 110 is operative to perform the methods described herein.

[0179] In one embodiment, a system is provided and comprises at least one network node N1 , N2 and a UE 110, both communicatively coupled to the radio network 100, the system comprises: at least one processor, and at least one memory, said memory containing instructions executable by said processor, whereby said system is operative to perform the methods described herein.

[0180] Fig. 11 illustrates a UE comprising functional modules according to one or more embodiments of the present disclosure. The UE comprising:

[0181] A receiver module 1110 configured to receiving mobility measurement configuration 610 from a network node N1 in the radio network, the mobility measurement configuration 610 being indicative of rules for selecting a set of TRP candidates for which the UE 110 should acquire downlink synchronization.

[0182] A measurement module 1120 configured to performing mobility measurements on TRP candidates in accordance with the measurement configuration.

[0183] An acquisition module 1130 configured to acquiring downlink synchronization for a first set of TRP candidates TRP1 , TRP3, TRP4 selected based on the rules and the mobility measurements.

[0184] A transmitting module 1140 configured to transmitting a mobility measurement report 620 to the node, the report indicating the downlink synchronized first set of TRP candidates.

[0185] In embodiments, the UE 110 may be configured to perform all the features described in relation to Fig. 8, or a subset of the features described in relation to Fig. 8.

[0186] Fig. 12 illustrates a network node N1 comprising functional modules according to one or more embodiments of the present disclosure. The network node N1 comprises:

[0187] A transmitter module 1210 configured to transmitting mobility measurement configuration 610 of the UE 110, the mobility measurement configuration 610 being indicative of rules for selecting TRP candidates for which the UE should acquire downlink synchronization. A receiver module 1220 configured to receiving a mobility measurement report 620 from the UE 110 in accordance with the mobility measurement configuration 610, the report 620 indicating TRP candidates TRP1 , TRP3, TRP4 for which the UE 110 has acquired downlink synchronization. In embodiments, the network node N1 may be configured to perform all the features described in relation to Fig. 10, or a subset of the features described in relation to Fig. 9.

[0188] Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

CLAIMS1. A computer-implemented method (800) for performing mobility measurements in a radio network (100), the method being performed by a user equipment, UE (110), in the radio network (100), the UE (110) being configured for multiple transmission and reception point, TRP, operation the method comprising: receiving (810) mobility measurement configuration (610) from a network node (N1) in the radio network, the mobility measurement configuration (610) being indicative of rules for selecting a set of TRP candidates for which the UE (110) should acquire downlink synchronization, performing (820) mobility measurements on TRP candidates in accordance with the mobility measurement configuration, acquiring (830) downlink synchronization for a first set of TRP candidates (TRP1 , TRP3, TRP4) selected based on the rules and the mobility measurements, transmitting (840) a mobility measurement report (620) to the network node, the report indicating the downlink synchronized first set of TRP candidates.

2. The method according to claim 1 , wherein mobility measurements are performed for a second set of TRP candidates (TRP1 , TRP3, TRP4, TRP6, TRP7, TRP8), and wherein the first set of TRP candidates (TRP1 , TRP3, TRP4) is selected from the second set.

3. The method according to any of the preceding claims, the method further comprising: determining timing information for the TRP candidates of the first set of TRP candidates, wherein the transmitted mobility measurement report further comprises the determined timing information.

4. The method according to claim 3, wherein determining timing information comprises measuring reception timing difference between TRP candidates of the first set of TRP candidates.

5. The method according to any of claims 2-4, wherein selecting the first set of TRP candidates comprises at least one of adding one or more TRP candidates of thesecond set to the first set of TRP candidates and removing one or more TRP candidates from the first set of TRP candidates.

6. The method according to any of the preceding claims, wherein the steps of performing mobility measurements and acquiring downlink synchronization is performed for a plurality of frequency layers, wherein the mobility measurement report (620) comprises a set of TRP candidates for each frequency layer.

7. The method according to any of the preceding claims, further comprising: receiving (850) a TRP change command from the network node, the change command indicating a change to one of the TRPs from the first set of TRP candidates, and changing serving TRP according to the TRP change command.

8. A user equipment, UE, (110) configured to perform mobility measurements in a radio network (100), the UE (110) being configured for multiple transmission and reception point, TRP, operation, the UE further configured to: receive a mobility measurement configuration (610) from a network node (N1) in the radio network, the mobility measurement configuration (610) being indicative of rules for selecting a set of TRP candidates for which the UE (110) should acquire downlink synchronization, perform mobility measurements on TRP candidates in accordance with the mobility measurement configuration, acquire downlink synchronization for a first set of TRP candidates (TRP1 , TRP3, TRP4) selected based on the rules and the mobility measurements, transmit a mobility measurement report (620) to the network node, the report indicating the downlink synchronized first set of TRP candidates.

9. The user equipment, UE, (110) of claim 8, further configured to perform the methods of any of claims 2-7.

10. A user equipment, UE, of a radio network (100), the UE comprising: a processor, anda memory, said memory containing instructions executable by said processor, whereby said UE is operative to perform the method according to any of claims 1-7.11 . A computer-implemented method (900) for configuring a user equipment, UE (110), to perform mobility measurements configuration in a radio network (100), the UE being configured for multiple transmission and reception point, TRP, operation, the method being performed by a network node (N1 ) in the radio network (100), the method comprising: transmitting (910) mobility measurement configuration (610) to the UE (110), the mobility measurement configuration (610) being indicative of rules for selecting TRP candidates for which the UE should acquire downlink synchronization, receiving (920) a mobility measurement report (620) from the UE (110) in accordance with the mobility measurement configuration (610), the report (620) indicating a set of TRP candidates (TRP1 , TRP3, TRP4) for which the UE (110) has acquired downlink synchronization.

12. The method according to claim 9, further comprising determining (930) one TRP candidate of the indicated set of TRP candidates (TRP1 , TRP3, TRP4) to change to, and transmitting (940) a TRP change command to the UE indicating a change to the determined TRP candidate.

13. The method according to any of claims 10, wherein the mobility measurement report (620) further comprises timing information for each of the TRP candidates of the set of TRP candidates, and wherein the TRP change command further comprises Timing Advance, TA, information determined based on the timing information.

14. A network node (N1) adapted to configure a user equipment, UE (110), to perform mobility measurements in a radio network, the UE being configured for multiple transmission and reception point, TRP, operation, the network node (N1) being configured to:transmit mobility measurement configuration (610) to the UE (110), the mobility measurement configuration (610) being indicative of rules for selecting TRP candidates for which the UE should acquire downlink synchronization, receive a mobility measurement report (620) from the UE (110) in accordance with the mobility measurement configuration (610), the report (620) indicating a set of TRP candidates (TRP1 , TRP3, TRP4) for which the UE (110) has acquired downlink synchronization.

15. The network node (N1) of claim 14, further configured to perform the methods of any of claims 12-13.

16. A network node (N1) of a radio network, the node (N1) comprising: a processor, and a memory, said memory containing instructions executable by said processor, whereby said node is operative to perform the method according to any of claims 11-13.

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