Cell selection upon fast failure recovery for ue configured with l1 / l2 triggered mobility

Abstract

There is provided a method performed by a UE. The method includes receiving a configuration including one or more L1 / L2 triggered mobility, LTM, candidate cell configurations, wherein each LTM candidate cell configuration is associated to an LTM candidate cell. In response to a radio related failure, the method includes selecting a suitable cell out of multiple suitable cells according to one or more rules. Further, in response to the selected suitable cell being a LTM candidate cell for which the UE received a LTM candidate cell configuration, the method includes performing one or more steps of an LTM cell switch procedure; and, in response to the selected suitable cell being a cell other than a LTM candidate cell for which the UE received a LTM candidate cell configuration, the method includes performing a re-establishment procedure. A related UE is also provided.

Description

CELL SELECTION UPON FAST FAILURE RECOVERY FOR UE CONFIGURED WITH L1 / L2 TRIGGERED MOBILITYTECHNICAL FIELDThe present disclosure relates to wireless communication systems, and in particular, to establishment of timing alignment in wireless communication systems.BACKGROUND

[0001] In Third Generation Partnership Project (3 GPP) Release 18, a work item referred to as further new radio (NR) mobility enhancements has been agreed. This work item includes a technical area entitled L1 / L2 based inter-cell mobility. According to the Work Item Description, when a user equipment (UE) moves from a coverage area of one cell to another cell, at some point a serving cell change needs to be performed. Currently, a serving cell change is triggered by L3 measurements and is done by radio resource control (RRC) signalling triggered reconfiguration with synchronization for change of a primary cell (PCell) and primary secondary cell (PSCell), as well as release add for secondary cells (SCells) when applicable. See e.g., RP -231475, 3GPP work item description: Further NR mobility enhancements, MediaTek Inc, Apple, 3GPP TSG RAN Meeting#100, Taipei (June 12-14, 2023). All cases involve complete L2 (and LI) resets, which may lead to longer latency, larger overhead and longer interruption time than beam switch mobility. A goal of L1 / L2 based inter-cell mobility includes to enable a serving cell change via L1 / L2 signalling, in order to reduce the latency, overhead and interruption time.

[0002] In this work item, the following is included as one objective of the work:1. To specify mechanism and procedures of L1 / L2 based inter-cell mobility for mobility latency reduction: o Configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells [RAN2, RAN3] o Dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1 / L2 signalling [RAN2, RANI] o LI enhancements for inter-cell beam management, including LI measurement and reporting, and beam indication [RANI, RAN2]Note 1 : Early RAN2 involvement is necessary, including the possibility of further clarifying the interaction between this bullet with the previous bullet o Timing Advance management [RANI, RAN2] o CU-DU interface signaling to support L1 / L2 mobility, if needed [RAN3]Note 2: FR2 specific enhancements are not precluded, if any.Note 3: The procedure of L1 / L2 based inter-cell mobility are applicable to the following scenarios:■ Standalone, CA and NR-DC case with serving cell change within one CG■ Intra-DU case and intra-CU inter-DU case (applicable for Standalone and C A: no new RAN interfaces are expected)■ Both intra-frequency and inter-frequency■ Both FR1 and FR2■ Source and target cells may be synchronized or non-synchronized.

[0003] A principle of Ll / L2-triggered mobility (LTM) is that a UE is pre-configured, by the network, with an RRC configuration per LTM candidate cell, sometimes referred to as a LTM candidate cell configuration. Such a LTM candidate cell configuration may be a RRCReconfiguration message or one or more information elements (IEs) / fields / parameters such as CellGroupConfig which is stored when the UE is configured with LTM. The UE transmits lower layer measurements (e.g., LI -reference signal received power (RSRP)) on these candidate LTM candidate cells to the network. In response, the UE receives from the network a lower layer signal (such as a medium access control (MAC) control element (CE) or downlink control information (DCI)) to trigger the execution of LTM cell switch in the UE (which may also be referred to as a LTM cell switch command): in response the UE accesses the LTM candidate cell indicated in the LTM cell switch command and switches to a configuration of an LTM candidate cell. When the UE is configured with multiple LTM candidate cells, the UE receives multiple LTM candidate cell configuration(s), e.g. multiple RRCReconfiguration messages to be stored, each associated to an LTM candidate ID which may be later referred in the LTM cell switch command the UE may receive, to indicate to which of the LTM candidate cells the UE needs to perform the LTM cell switch.

[0004] In Rel-18, LTM is supported in a central unit (CU) / distributed unit (DU) split architecture, in which a gNodeB may be split into a CU and DU, and an LTM candidate cell may either be from the Source DU (S-DU), denoted as the same DU of the UE’ s current serving cell(s), e.g. Master Cell Group, or from a neighbour DU, denoted Candidate DU (C-DU), associated to the same CU, e.g., LTM in Rel-18 supports intra-CU intra- / inter-DU cases. Figurel is a sequence diagram showing a summary of the preparation procedures only for the inter- DU case, for simplicity, as discussed in the latest version of the running CR for TS 38.401 (see https: / / www.3gpp.org / ftp / tsg_ran / WG3_Iu / TSGR3_120 / Docs / R3-233495.zip (accessed on 7 August 2023). The procedure is used for a case when the UE 100 moves from one gNB-DU 102 to another gNB-DU 104 within the same gNB-CU 106 during NR operation for LTM.

[0005] In operation 1, the UE 100 sends a MeasurementReport message (e.g., L3 measurement result for future study (FFS)) to the source gNB-DU 102 containing measurements of neighboring cells. The source gNB-DU 102 sends an UL RRC MESSAGE TRANSFER message conveying the received MeasurementReport message to the gNB-CU 106.

[0006] The gNB-CU 106, in operation 2, determines to initiate LTM configuration.

[0007] In operation 3, the gNB-CU 106 sends a UE CONTEXT SETUP REQUEST message to the candidate gNB-DU 104, containing one target candidate cell ID.

[0008] In operation 4, the candidate gNB-DU 104 accepts the request of LTM configuration, and responds to the gNB-CU 106 with a UE CONTEXT SETUP RESPONSE message including the generated lower layer RRC configuration for the accepted target candidate cell.

[0009] In operation 5, the gNB-CU 106 sends a DL RRC MESSAGE TRANSFER message to the source gNB-DU 102, which includes the generated RRCReconfiguration message with the LTM configuration. FFS: whether it is DL RRC MESSAGE TRANSFER message or UE CONTEXT MODIFICATION REQUEST message.

[0010] The source gNB-DU 102, in operation 6, forwards the received RRCReconfiguration message to the UE 100.

[0011] In operation 7, the UE 100 responds to the source gNB-DU 102 with an RRCReconfigurationComplete message.

[0012] In operation 8, the source gNB-DU 102 forwards the RRCReconfigurationComplete message to the gNB-CU 106 via an UL RRC MESSAGE TRANSFER message. FFS: whether it is UL RRC MESSAGE TRANSFER message or UE CONTEXT MODIFICATION RESPONSE message.

[0013] UE 100, in operation 9, sends the lower layer measurement result to the source gNB-DU 102.

[0014] In operation 10, the source gNB-DU 102 decides to execute LTM to a candidate target cell. FFS: Notifying the LTM triggering decision to the other nodes as well.

[0015] In operation 11, the source gNB-DU 102 sends LTM command to the UE 100.

[0016] WA: In operation 12, the source gNB-DU 102 sends the LTM CELL CHANGE NOTIFICATION message to the gNB-CU 106 to indicate the initiation of the LTM command to the UE 100 including the target cell ID.

[0017] In operation 13, the target gNB-DU 104 sends the ACCESS SUCCESS message to the gNB-CU 106 with the target cell ID.

[0018] In operation 14, the gNB-CU 106 may send the UE CONTEXT RELEASE COMMAND message to the source gNB-DU 102 to release the resources of prepared cells.

[0019] In operation 15, the source gNB-DU 102 responds with a UE CONTEXT RELEASE COMPLETE message.

[0020] It has also been agreed that when a UE receives the LTM cell switch command and executes LTM the UE starts a supervision timer, whose behavior has been defined as follows:=> Following behaviors of LTM supervisor timer are agreed:- 1 : The UE starts the LTM supervisor timer, upon reception of the LTM cell switch MAC CE;- 2: The UE stops the LTM supervisor timer, upon successful completion of LTM cell switch;- 3 : If the LTM supervisor timer for MCG expires, as baseline, the UE considers LTM failure and initiates RRC re-establishment. (SCG switch case FFS)=> At RLF or LTM execution failure (for MCG), RAN2 intend to support fast recovery to a candidate cell by LTM execution.

[0021] There currently exist certain challenge(s). As discussed herein, a UE determines an LTM failure when a supervision timer expires (e.g., the supervision had been started when the UE received the LTM cell switch command indicating one of the configured LTM candidate cells).

[0022] In the RAN2#121bis meeting there was a high level agreement to support fast recovery to a candidate cell by LTM execution, at radio link failure (RLF) or LTM execution failure (for a master cell group (MCG)), but no details were agreed.

[0023] One approach for fast recovery that may be specified in 3GPP TS 38.331, V17.5.0 is the UE selecting an LTM candidate cell(s) upon detecting an LTM failure (e.g., expiry of the supervision timer). An example of how this may be specified in 3GPP TS 38.331 may be as follows (the supervision timer being denoted by T3xx):[38.331]5.3.5.8.X T3xx expiry (LTM cell switch failure)The UE shall:1> if T3xx of MCG expires:[ •]2> initiate the connection re-establishment procedure as specified in clause 5.3.7. [...]5.3.7 RRC connection re-establishment[...]5.3.7.2 InitiationThe UE initiates the procedure when one of the following conditions is met:1> upon detecting radio link failure of the MCG while configure with one or moreLTM candidate cells [...]; or[...] l>upon detecting an LTM cell switch failure, in accordance with 5.3.5.8.X; or[...]Upon initiation of the procedure, the UE shall:[...]1> if UE is not configured with attemptCondReconfig:[...]1> if the UE is acting as L2 U2N Remote UE:[...]1> else:2> if the UE is capable of L2 U2N Remote UE:[...]2> else:3> perform cell selection in accordance with the cell selection process as specified in TS 38.304

[0020] ,[...]5.3.7.3 Actions following cell selection while T311 is runningUpon selecting a suitable NR cell, the UE shall:[...]1> if the selected cell is one of the LTM candidate cells the UE is configured with:1> apply the LTM configuration according to clause 5.3.5.3 (e.g. in ue-LTM- Config within VarLTM-UE-Config), related to the LTM candidate cell configuration identity associated to the selected cell;[...] l>else:[...]2> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;[...]

[0024] A first scenario which may occur is when the UE is configured with multiple LTM candidate cell(s), receives the LTM cell switch command for one of the LTM candidate cells, starts the supervision timer (denoted above by T3xx) and the supervision timer expires (e.g., the UE detects an LTM cell switch failure). A second scenario which may occur is when other types of failures are detected while the UE is configured with multiple LTM candidate cell(s), e.g. an RLF, handover failure, reconfiguration with synchronization failure, beam failure recovery (BFR), etc.

[0025] In both scenarios, it is only specified that the UE selects a suitable cell (e.g., while timer T311 is running), which may possibly be an LTM candidate cell or not. Additionally, there may be multiple suitable cells, wherein some may be LTM candidate cells and some may not LTM candidate cells; and it is not specified which of the cells among the suitable cells the UE shall select. In other words, the criteria for selecting a suitable cell when there may be multiple suitable cells is left to UE implementation. A suitable cell in that context, as defined in 3GPP TS 38.340, is a cell on which a UE may camp. For a NR cell, that is a cell which fulfills among other higher layer criteria the cell selection criteria, defined as follows in 3GPP TS 38.304, V17.5.0:[38.304]The cell selection criterion S is fulfilled when:Srxlev > 0 AND Squal > 0 where:SrxleV Qrxlevmeas—(Qrxlevmin + Qrxlevminoffset )—P compensation—QoffsettempSqual Qqualmeas—(Qqualmin + Qqualminoffset)—Qoffsettemp where:

[0026] Selecting a suitable cell, or rather any suitable cell, means that the cell has good enough radio conditions in terms of RSRP and reference signal received quality (RSRQ). However, that may lead to disadvantages such as: o The UE selects a cell, which is a suitable cell, and which is an LTM candidate cell and, after applying the associated LTM candidate cell configuration and accessing that LTM candidate cell, the UE transmits a measurement report and receives a handover command, triggered to another cell (which may have been selected), which may lead to a waste of signaling which consumes power / energy at the UE and may increase interruption time and disrupt service continuity; o The UE selects a cell, which is a suitable cell, and which is an LTM candidate cell and, after applying the associated LTM candidate cell configuration and accessing that LTM candidate cell, the UE transmits lower layer measurement reports and receives an LTM cell switch command indicating another of the LTM candidate cells (which may have been selected): This may represent a waste of signalingwhich consumes power / energy at the UE and may increase interruption time and disrupt service continuity; o The UE selects a cell, which is a suitable cell, which is not an LTM candidate cell and, after triggering re-establishment the UE to that cell the UE transmits measurement reports and receives a handover command to another cell, which may be a previous LTM candidate cell: In that case, the UE may have lost the opportunity to directly perform an LTM cell switch and instead triggered a re-establishment followed by a handover, which may consume much more power / energy at the UE, and may increase interruption time and disrupt service continuity; o The UE selects a cell, which is a suitable cell, which is not an LTM candidate cell and, after triggering re-establishment the UE to that cell the UE transmits measurement reports and receives a handover command to another cell (not a previous LTM candidate cell): In that case, the UE may have lost the opportunity to directly perform the re-establishment to that target cell, which may lead to more signaling required for the handover, more power / energy at the UE, increased interruption time and disrupted service continuity.

[0027] In other words, selecting a suitable cell without further criteria (e.g., as presently specified by 3GPP) in scenarios in which there are multiple suitable cells may lead to disadvantages, e.g., when there are multiple suitable cells.SUMMARY

[0028] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. The present disclosure includes operations of a UE that is configured with one or more LTM candidate cells to perform fast recovery from radio related failures.

[0029] There is provided a method performed by a UE. The method includes receiving a configuration including one or more L1 / L2 triggered mobility, LTM, candidate cell configurations, wherein each LTM candidate cell configuration is associated to an LTM candidate cell. In response to a radio related failure, the method includes selecting a suitable cell out of multiple suitable cells according to one or more rules. Further, in response to the selected suitable cell being a LTM candidate cell for which the UE received a LTM candidate cell configuration, the method includes performing one or more steps of an LTM cell switch procedure; and, in response to the selected suitable cell being a cell other than a LTM candidate cell for which the UE received a LTM candidate cell configuration, the method includes performing a re-establishment procedure.

[0030] In some embodiment the method further comprises detecting a radio related failure.

[0031] There is also provided a UE. The UE includes a processing circuitry configure to receive a configuration including one or more L1 / L2 triggered mobility, LTM, candidate cell configurations, wherein each LTM candidate cell configuration is associated to an LTM candidate cell. In response to a radio related failure, the processing circuitry is configured to select a suitable cell out of multiple suitable cells according to one or more rules. Further, in response to the selected suitable cell being a LTM candidate cell for which the UE received a LTM candidate cell configuration, the processing circuitry is configured to perform one or more steps of an LTM cell switch procedure; and, in response to the selected suitable cell being a cell other than a LTM candidate cell for which the UE received a LTM candidate cell configuration, the processing circuitry is configured to perform a re-establishment procedure.

[0032] In some embodiments the processing circuitry is configured to detect a radio related failure.

[0033] The selecting a suitable cell out of multiple suitable cells according to one or more rules comprises at least one of the following rules: select a suitable cell in a same frequency as a frequency of the UE’s current primary cell, select a suitable cell in a same frequency as a frequency of an LTM candidate cell indicated in an LTM cell switch command, select a suitable cell for which the UE has a valid timing advance, TA, and at the same time is an LTM candidate cell, select a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or re-selection procedure and at the same time is an LTM candidate cell, select a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE, select a suitable cell for which the UE has established a downlink, DL, synchronization, select a suitable cell based on a LI measurement report, select a suitable cell based on a L3 measurement, select a suitable cell in a lower frequency or a lower frequency range, select a suitable cell with a short synchronization signal block, SSB, periodicity, select a strongest LTM candidate cell out of N suitable cells according to a measurement quantity, wherein a measurement quantity corresponds to at least one of a reference signalreceived power, RSRP, a reference signal received quality, RSRQ, and a signal to interference plus noise ratio, SINR. select a suitable cell that is controlled by a same network node as a network node controlling the PCell in which the radio related failure was detected, select a suitable cell that is controlled by a different network node than a network node controlling the PCell in which the radio related failure was detected, select a suitable cell towards which an LTM cell switch does not result in an L2 reset, select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells, select a suitable cell that is currently configured as an activated secondary cell, SCell, and select a suitable cell in a different frequency than frequencies for which measurement events are configured.

[0034] Certain embodiments may provide one or more of the following technical advantage(s). One overall benefit is to try to make the UE actions upon failure detection as close as possible to the actions as if a failure would have not happened.

[0035] In example operations, the UE, in response to detecting a radio related failure (e.g., LTM cell switch failure or RLF), select a cell, wherein the UE selects a suitable cell out of multiple suitable cells according to one or more rules. In response the UE selectively performs: (i) one or more steps of an LTM cell switch procedure when the selected cell has been determined to be a LTM candidate cell (for which the UE has a stored LTM candidate cell configuration); or (ii) a re-establishment procedure when the selected cell has been determined to be a cell which is not an LTM candidate cell the UE is configured with.

[0036] In one example, the UE selects one suitable cell out of multiple suitable cells according to one or more rules that may comprise that the UE selects one of the configured LTM candidate cells when there is at least one suitable cell which is an LTM candidate cell among the multiple suitable cells.

[0037] In yet a further example, the UE can use a combination of two or more of the rules for the selection of a suitable cell. For example, the UE may select a suitable cell based on a first rule X and a second rule Y, or based on a first rule X, a second rule Y and a third rule Z, and so on.

[0038] Thus, example operations of the UE include the UE selecting a suitable cell out of multiple suitable cells according to one or more rules. The rules can be used for the UE to select the suitable cell out of multiple suitable cells to selectively perform a re-establishmentprocedure (when the selected cell is not an LTM candidate) or to perform one or more steps of an LTM cell switch procedure (when the selected cell is an LTM candidate). When the UE performs one or more steps of an LTM cell switch procedure for the selected cell, the UE can apply the stored LTM candidate cell configuration associated to the selected cell and transmit, in the selected cell, a notification message (e.g., a RRC Reconfiguration Complete message).

[0039] Without one or more rules for selecting a suitable cell, beyond the cell selection criteria specified in 3GPP TS 38.304 for example, there may be multiple suitable cells, wherein some may be LTM candidate cells and some may not be LTM candidate cells; and it is not specified which of the cells among the suitable cells the UE may select. In other words, the criteria for selecting a suitable cell when there may be multiple suitable cells is left to UE implementation. Selecting any suitable cell may mean that the cell has good enough radio conditions in terms of RSRP and RSRQ. Based on the inclusion of one or more rules, one or more challenges may be prevented and one or more of the following technical advantages may be provided: o When the UE selects a cell which is an LTM candidate cell and, after applying the associated LTM candidate cell configuration and accessing that LTM candidate cell, that is a stable cell and handovers may not immediately follow. For example, the UE may not receive a handover command shortly after a failure recovery triggered to another cell. Thus, as a consequence of operations of the method, the UE may not transmit / receive unnecessary signaling, which may save power / energy at the UE and / or may prevent an interruption time and service disruption; o When the UE selects a cell which is an LTM candidate cell and, after applying the associated LTM candidate cell configuration and accessing that LTM candidate cell, the UE may not shortly receive an LTM cell switch command indicating another of the LTM candidate cells. Thus, as a consequence of operations of the method, there may not be unnecessary signaling and, thus, the UE may reduce its power / energy consumption, and / or may minimize the interruption time and service disruption; o When the UE selects a cell which is not an LTM candidate cell and, after triggering re-establishment of the UE with a stable cell, the UE may not shortly receive a handover command to another cell or even an LTM cell switch command. Thus, as a consequence of operations of the method, the UE may prevent a handover or LTMcell switch shortly after re-establishment, which may save signaling and / or UE power / energy consumption.

[0040] Thus, as a consequence of operations of the method, the one or more rules may enable a UE to save power / energy as a consequence of the UE avoiding exchanging unnecessary signaling between the UE and the network (e.g., in case an LTM cell switch or handover occurs shortly after the fast recovery, which would have indicated that the selected cell was not the best). Additionally, there may be a potential gain in robustness since mobility procedures (e.g., handover or LTM cell switches) shortly after fast recovery are an indication that the selected cell, even though suitable, is not the best, which may mean some risk of radio link failures, handover failures, or LTM cell switch failures shortly after the fast recovery.BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure l is a sequence diagram showing a summary of the preparation procedures only for the inter-DU case.

[0042] Figure 2 is a sequence diagram of an example in accordance with some embodiments.

[0043] Figure 3 is a flow chart of operations of UE performed in accordance with some embodiments.

[0044] Figure 4 shows an example of a communication system in accordance with some embodiments.

[0045] Figure 5 shows a UE in accordance with some embodiments.

[0046] Figure 6 shows a network node in accordance with some embodiments.

[0047] Figure 7 is a block diagram of a host.

[0048] Figure 8 is a block diagram illustrating a virtualization environment.

[0049] Figure 9 shows a communication diagram of a host.DETAILED DESCRIPTION

[0050] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0051] As referred to herein, the phrase “L1 / L2 based inter-cell mobility” refers without limitation to the Work Item Description in 3GPP discussed herein. This phrase further refers to, and may be interchangeable with, the terms L1 / L2 mobility, Ll-mobility, LI basedmobility, Ll / L2-centric inter-cell mobility, L1 / L2 inter-cell mobility Ll / L2-triggered mobility, lower-layer triggered mobility, or LTM.

[0052] A principle of some examples herein includes that a UE receives a lower layer signaling from the network indicating to the UE a change (or switch or activation, for example) of its serving cell (e.g., change of PCell from a source to a target PCell), wherein a lower layer signaling is a message / signaling of a lower layer protocol, which may be referred as a L1 / L2 inter-cell mobility execution command or a LTM cell switch command. The change of serving cell (e.g. change of PCell) may also lead to a change in SCell(s) for the same cell group, e.g. in case the command triggers the UE to change to another cell group configuration of the same type (e.g., another MCG configuration). Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more LTM candidate cell configurations (e.g., reception of an RRC Reconfiguration message, with at least one LTM candidate cell configuration). A LTM candidate cell configuration may include parameters in the IE CellGroupConfig per candidate cell and / or an embedded RRC Reconfiguration per LTM candidate cell, for example.

[0053] As referred to herein, the phrase “LTM cell switch procedure” refers to a process of a UE switching (or changing) its cell from a source cell to a target cell (which may be referred to herein as an LTM candidate cell or a neighbour cell), using LI / L2 -triggered mobility (LTM). In the context of LTM, an LTM cell switch procedure also may be referred to as a L1 / L2 based inter-cell mobility execution, LTM execution, dynamic switch, LTM switch, (LTM) cell switch, (LTM) serving cell change, or (LTM) cell change. In the context of the present disclosure, switching to the LTM candidate cell configuration includes the UE considering that an LTM candidate cell becomes its new special cell (SpCell) (e.g. PCell in case of LTM being configured for a MCG and / or PSCell in case of LTM being configured for a secondary cell group (SCG)); or, changing its SpCell from the current PCell to an LTM candidate cell.

[0054] The term “change of cell” includes a change of a whole cell group configuration, which includes a change in the SpCell (e.g., change of PCell, or change of PSCell) and a change in SCells of the cell group (e.g., addition, modification and / or release of one or more SCells).

[0055] An LTM cell switch procedure may be triggered in the UE by reception of a LTM cell switch command, or alternatively, triggered by some other event, such as a condition (e.g., a triggering condition used for conditional configuration, such as conditional handover) being fulfilled as a result of recovery from radio link failure or handover failure.

[0056] As referred to herein, a “LTM candidate cell” refers to a cell the UE is configured with when configured with Ll / L2-triggered mobility. That is, a cell the UE can move to in a LTM cell switch procedure, upon reception of a LTM cell switch command. These cells may also be referred to as candidate cell(s), candidates, mobility candidates, non-serving cells, additional cells, target candidate cell, target candidate, etc. A LTM candidate cell is a cell the UE perform measurements on (e.g., CSI measurements) so that the UE reports these measurements and the network may take an educated decision on which beam (e.g., transmission configuration indication (TCI) state) and / or cell the UE is to be switched to. An LTM candidate cell may be a candidate to be a target PCell or PSCell, or an SCell of a cell group (e.g. MCG SCell).

[0057] As discussed herein, there may be at least one LTM candidate cell configuration and the UE may have received at least one LTM candidate cell configuration. The phrase “at least one LTM candidate cell” also may be referred to as a configuration of a LTM candidate cell, which may be an RRC configuration, such as encapsulated in an RRC Reconfiguration message, that the UE receives when being configured with L1 / L2 -triggered mobility. A LTM candidate cell configuration includes the configuration the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to that LTM candidate cell (e.g., upon reception of the LTM cell switch command indicating the UE to perform a LTM cell switch procedure to that LTM candidate cell) which becomes the target cell and the current (new) SpCell, or an SCell in a serving frequency.

[0058] The LTM candidate cell configuration can include parameters of a serving cell (or multiple serving cells, such as a cell group), including one or more of the groups of parameters, such as an RRCReconfiguration message, an IE CellGroupConfig, or an IE SpCellConfig (or the IE SCellConfig, in the case of a Secondary Cell).

[0059] In one example, a LTM candidate cell configuration includes one or more of: (i) the PCell configuration and one or more SCell configuration(s) of a MCG; and (ii) the PSCell configuration and one or more SCell configuration(s) of a SCG. The terms (LTM) candidate configuration, LTM configuration, (LTM) candidate target cell configuration, (LTM) target candidate (cell) configuration may be used interchangeably when referring to LTM candidate cell configuration. An LTM candidate cell configuration is associated with an identifier which is used in the signaling when referring to a certain LTM candidate cell configuration, such as when the UE receives the LTM candidate cell configuration and when the UE receives an LTM cell switch command indicating the UE to perform a LTM cell switch procedure to that LTMcandidate cell. This identifier also can be referred to as the LTM candidate cell configuration identity or LTM candidate configuration index, etc.

[0060] The actual LTM candidate cell configuration, and its exact content and / or structure of an IE and / or embedded message may be called an RRC model for the candidate configuration, or simply an RRC model.

[0061] An LTM candidate cell configuration includes the configuration which the UE needs to operate accordingly when it performs (executes) L1 / L2 based inter-cell mobility execution to a LTM candidate cell, upon reception of the lower layer signaling (e.g., MAC CE) indicating a L1 / L2 based inter-cell mobility to a LTM candidate cell (which becomes the target cell and the current (new) PCell, or an SCell in a serving frequency), or upon reception of the lower layer signaling (e.g., MAC CE) indicating a L1 / L2 based inter-cell mobility to a LTM candidate cell configuration indicated with a candidate configuration index (sometimes also referred to as candidate configuration ID).

[0062] The UE may be configured with multiple LTM candidate cell configurations, so a candidate DU can generate and send to a CU multiple configuration(s). The actual LTM candidate cell configuration the UE receives during the LTM configuration may be a delta signaling to be applied on top of a reference configuration, so that the actual configuration the UE is to use in the candidate cell upon LTM cell switch is the combination of the LTM candidate cell configuration and the reference configuration (e.g., separately signaled by the network to the UE).

[0063] As discussed herein, in some example, the UE has a stored LTM candidate cell configuration for an LTM candidate cell. A stored LTM candidate cell configuration for an LTM candidate cell may have been received when being configured with L1 / L2 -triggered mobility (e.g., in an RRC Reconfiguration message which includes an LTM candidate cell configuration). The stored LTM candidate cell configuration may be a combination of a received LTM candidate cell configuration (which uses delta signaling) and the reference configuration (e.g., separately signaled by the network to the UE). The stored LTM candidate cell configuration may alternatively be obtained by the UE by other means, e.g. preconfigured, a default or specified configuration, restored after exiting idle mode or a UE power saving state such as transition from RRC INACTIVE to RRC CONNECTED state, read from a memory card, or by other means been provided out-of-band outside of 3 GPP specified interfaces or as user data.

[0064] As discussed herein, operations of examples refer to a suitable cell and that the UE has selected a suitable cell. An example of conditions for a suitable cell is that the UE is ableto camp on the cell and the cell fulfils the cell selection criteria. For example, during the cell selection process, the UE selects a suitable cell. The selection of a suitable cell may imply the UE selects any cell which is considered as suitable cell, or selects a cell among multiple cells that all are considered as suitable. Examples of conditions that defines a suitable cell include are those that are specified in 3GPP TS 38.304, V17.5.0 including, for example:• The cell is part of either the selected public land mobile network (PLMN) or the registered PLMN or PLMN of the equivalent PLMN list, and for that PLMN either: o The PLMN-ID of that PLMN is broadcast by the cell with no associated carrier aggregation group (CAG)-IDs and CAG-only indication in the UE for that PLMN (TS 23.501

[0010] ) is absent or false; o Allowed CAG list in the UE for that PLMN (TS 23.501

[0010] ) includes a CAG- ID broadcast by the cell for that PLMN; o The cell selection criterion S is fulfilled as specified in 3GPP TS 38.304 according to Srxlev > 0 AND Squal > 0.■ In other words, when the cell selection criterion S is fulfilled it means that the cell has good enough radio conditions in terms of RSRP and RSRQ.

[0065] During cell selection to find a suitable cell, the UE may or may not use prior knowledge and / or stored information, such as knowledge of frequencies and / or measurement information previously obtained. This may be referred to as cell selection leveraging stored information. In some examples, when no such information is available or cell selection using such information resulted in that no suitable cell was found, the UE falls back to use what may be referred to as initial cell selection which may include a scan of radio frequency (RF) channels in relevant bands and searching for the strongest cell(s).

[0066] In some examples, as cell selection may result in that the UE identifies multiple cells that are classified as suitable cells, it may be up to the UE implementation to select one of these cells, which may include using other criteria not specified as requirements, such as a cell that is configured as an LTM candidate cell.

[0067] The term “beam” may correspond to a spatial direction in which a signal is transmitted (e.g., by a network node) or received (e.g., by the UE), or a spatial filter applied to a signal which is transmitted or received. Thus, in some examples, transmitting signals different beams can correspond to transmitting signals in different spatial directions. The phrase “beam which is selected” or similar may refer to a beam index and / or a reference signal (RS) index oridentifier, such as a synchronization signal block (SSB) index, or a channel state informationreference signal (CSI-RS) resource identifier. Thus, selecting a beam may correspond to selecting an SSB, associated to an SSB index, selecting a CSI-RS, or associated to a CSI-RS resource identifier.

[0068] As referred to herein, a radio related failure may be triggered for a MCG or a SCG and may be one of• A beam failure detection (BFD), e.g. as defined in 3GPP TS 38.321, V17.5.0;• A failure to execute a LTM cell switch procedure, e.g. expiry of the LTM supervision timer;• A handover failure (HOF) or reconfiguration with sync failure, e.g. expiry of timer T304;• A radio link failure (RLF), e.g. expiry of timer T310 or T316; and / or• A RLC unrecoverable error, e.g. a failure to (re)transmit a maximum number N of RLC packet data unit (PDU) (e.g., that the maximum number of retransmissions has been reached for an RLC entity as defined in 3GPP TS 38.322, V17.3.0).

[0069] In examples discussed herein, references to the “network” refer to a network entity or network node from which the UE receives one or more configurations and / or parameters, such as LTM candidate configuration(s).

[0070] In an example, a UE, in response to detecting a radio related failure (e.g., LTM cell switch failure or RLF), selects a cell, wherein the UE selects a suitable cell out of multiple suitable cells according to one or more rules. In response, the UE selectively performs: (i) one or more steps of an LTM cell switch procedure when the selected cell has been determined to be a LTM candidate cell (for which the UE has a stored LTM candidate cell configuration); or (ii) a re-establishment procedure when the selected cell has been determined to be a cell which is not an LTM candidate cell the UE is configured with.

[0071] The UE can select a suitable cell out of multiple suitable cells according to one or more rules. The one or more rules include one or more of the following:

[0072] First rule: The UE selects one of the configured LTM candidate cells when there is at least one suitable cell which is an LTM candidate cell among the multiple suitable cells.

[0073] In some examples, the UE has stored the LTM candidate configuration(s) for LTM candidates (e.g., A, B, C, D) and, when the failure is detected, a subset of LTM candidate cells are suitable (e.g., A, B are LTM candidate cells which are suitable), in addition to other suitable cells (e.g., E and F). Thus, the UE has as suitable cells the cells A (LTM candidate), B (LTMcandidate), E, F. According to the first rule, the UE selects the cell A or the cell B. Another rule may be applicable for determining which one among A and B are to be selected. A technical advantage in selecting a suitable LTM candidate cell may be that the UE performs an LTM cell switch execution instead of re-establishment, which may reduce signaling exchanged between the UE and the network, may reduce the UE’s energy consumption, and / or may improve the resource usage as LTM is a more efficient than a re-establishment.

[0074] In one example, the first rule is always applied regardless of other conditions: when there is at least one suitable LTM candidate cell, the UE always selects that one, regardless of the existence of other suitable cells (e.g., which may have better radio conditions, such as RSRP and / or RSRQ). A technical advantage may be that the LTM cell switch is executed, whenever it is possible, instead of re-establishment, which may reduce signaling exchanged between the UE and the network, may reduce the UE’s energy consumption, and / or may improve the resource usage as LTM is a more efficient than a re-establishment.

[0075] In another example, there is one or more exception(s) in which the rule is not applied, including: o The rule is applied except when the suitable LTM candidate cell(s) are not in the same frequency as the PCell in which the radio related failure was detected, or the PCell the UE was coming from when an LTM cell switch failure or handover failure was detected. A technical advantage of having such an exception may be that the UE tries to select a suitable LTM candidate cell in the same frequency as the PCell, which means that the UE tries to benefit from executing LTM and stay in the same frequency as the previous PCell, which is the frequency which the network prefers the UE to be (which may consider aspects the UE may not be aware of, such as load distribution across multiple frequencies deployed by the network). Thus, this may prevent the UE performing an LTM cell switch to a suitable LTM candidate cell in a frequency (e.g., Fl) different than the UE’s previous PCell frequency (e.g., F0) and, after the LTM cell switch, the network anyways triggering an inter-frequency handover or inter-frequency LTM cell switch for that UE; o The rule is applied except when the suitable LTM candidate cell(s) have much worse radio conditions than the strongest suitable cell which is not an LTM candidate cell. For example, when the suitable LTM candidate cells (in the previous example) have RSRP (LTM candidate A), RSRP (LTM candidate B) and another suitable cell which is not an LTM candidate has RSRP (cell E)» RSRP (LTM candidate A) and RSRP (cell E) » RSRP (LTM candidate B), the UE selects thesuitable cell E. A technical advantage of such an exception may be that the UE triggers an LTM cell switch most of the time, which may have the technical advantages described above; however, when there is a much better suitable cell the UE does not select the LTM candidate cell and a technical advantage may be that the UE would otherwise perform an LTM cell switch likely followed by a handover; and / or o The rule is applied except when the suitable LTM candidate cell(s) are in a frequency which differs from the PCell frequency (e.g., SSB frequency and / or subcarrier spacing) and there is at least one suitable cell (which is not an LTM candidate cell) in the same frequency as the PCell (in the case of an RLF) or the same frequency as the source PCell or the same frequency as the LTM candidate cell indicated in the LTM cell switch command, in case of an LTM cells switch failure. A technical advantage in having such an exception may be that the UE selects a cell in a frequency which the network seems to want the UE to be (e.g., due to load related reasons), which avoids the UE to execute an LTM cell switch to a frequency and, shortly receive a handover command to another cell in the previous frequency. Thus, as a consequence of this exception, a handover shortly after the LTM cell switch may be prevented.

[0076] In a further example, the UE has been configured with at least a first LTM candidate cell and at least a second LTM candidate cell, and the UE receives an LTM cell switch command including an indication of the first LTM candidate cell (e.g. MAC CE including an LTM candidate ID). When that LTM cell switch procedure with the first LTM candidate cell fails, the UE selects the second LTM candidate cell and performs the LTM cell switch to that cell (e.g., the UE accesses the second LTM candidate cell).

[0077] Second rule: The UE selects a suitable cell in the same frequency as the frequency of the UE’s current primary cell (e.g., SSB frequency of the UE’s PCell). o In one example, being in the same frequency means for example that the selected cell has the same SSB frequency as the SSB frequency of the UE’s current primary cell and / or that the selected cell has the same subcarrier spacing the UE’s current primary cell. o In another example, the selected cell in the same frequency as the UE’s current PCell frequency is a cell for which the UE has a stored LTM candidate cell configuration, so that after cell selection the UE applies the stored LTM candidate cell configuration and accesses the selected cell with an LTM cellswitch. In another example, the selected cell, in the same frequency as the UE’s current PCell frequency, is a cell for which the UE does not have a stored LTM candidate cell configuration, so that after cell selection the UE continues with an RRC Re-establishment procedure with the selected cell (e.g., by transmitting an RRC Reestablishment request). In a sub-example, the UE searches for a cell in the same frequency as the frequency of the UE’s current PCell for which the UE has a stored LTM candidate cell configuration and selects that one. o In another example, this rule for cell selection occurs when the failure which leads to the cell selection procedure is a radio link failure on the primary cell. o In yet another example, this rule for cell selection occurs when the failure which leads to the cell selection procedure is a handover failure (e.g., expiry of the timer T304); o In another example, this rule for cell selection occurs when the failure which leads to the cell selection procedure is a handover failure (e.g., expiry of the timer T304) and the handover command (e.g., RRCReconfiguration including a reconfiguration with synchronization IE) to a target cell which is in the same frequency as the UE’s current PCell. o In yet another example, this rule for cell selection occurs when the failure which leads to the cell selection procedure is an LTM cell switch failure (e.g., expiry of a supervision timer for LTM, maximum number of attempts is reached, etc.) and the LTM cell switch command indicates an LTM candidate cell which is in the same frequency as the UE’s current PCell.

[0078] Third rule: The UE selects a suitable cell in the same frequency as the frequency of an LTM candidate cell indicated in an LTM cell switch command. o In one example, being in the same frequency means, e.g., that the selected cell has the same SSB frequency and the UE’s current primary cell and / or that the selected cell has the same subcarrier spacing the UE’s current primary cell. o In another example, the UE has been configured with at least a first LTM candidate cell in the same serving frequency as the UE’s current primary cell (e.g., special cell, special cell of the MCG, PCell, PSCell, special cell of the SCG) and at least a second LTM candidate cell which is not in the in the same serving frequency as the UE’s current primary cell. The UE receives an LTM cell switch command including an indication of the first LTM candidate cell (e.g., MAC CE including an LTM candidate ID) and when the LTM cell switch procedure failsfor the first LTM candidate cell, the UE selects a cell in the same serving frequency as the UE’s current primary cell (e.g., the UE does not select a cell in another frequency, even if that cell is a cell for which the UE has a stored LTM cell switch). Thus, the UE triggers a re-establishment procedure (e.g., by transmitting an RRC Reestablishment Request message) with the selected cell in the UE’s current serving frequency.

[0079] Fourth rule: The UE selects a suitable cell for which it has a valid timing advance (TA), for example when the UE has received an timing advance value and / or an time alignment timer (TAT) is running. A technical advantage of selecting that cell among cells for which the UE has available coverage may be that the access may be much faster. For example, when there is a valid TA, the UE may avoid random access procedure towards that cell.

[0080] Fifth rule: The UE selects a suitable cell whose frequency is part of a configuration provided to the UE for performing the cell (re)selection procedure, and at the same time is an LTM candidate cell. o In one example, the UE is provided with a set of frequencies that the UE scans first when performing a cell (re)selection procedure and, if there is also a LTM candidate cell deployed on one or more of these frequencies, the UE prioritizes these frequencies first. o If there is more than an LTM candidate cell that is deployed on a frequency that is also part of a configuration that the UE uses for performing the cell (re)selection procedure, the UE may prioritize one of this cell according to one or more of the following:■ The cell deployed on FR1 is prioritized.■ The cell deployed on FR2 is prioritized.■ The cell for which LTM cell switch information are available is prioritized.■ The cell deployed on the same frequency of the current UE primary cell is prioritized.■ The cell deployed on the same radio access network (RAN) area (RNA) of the current UE primary cell is prioritized.■ The cell deployed on the same TA of the current UE primary cell is prioritized.■ The cell for which the UE has already UL synchronization is prioritized.■ The cell for which the UE has already DL synchronization is prioritized.■ The cell for which the UE has already UL and DL synchronization is prioritized.

[0081] Sixth rule: The UE selects a suitable cell for which an LTM candidate configuration is available and further selects the cell based in the order in which the LTM candidate configuration is provided to the UE. o In one example, the UE is configured with at least more than one LTM candidate cell configuration and the LTM candidate cell configuration are provided in a list. In this example, the UE considers the LTM candidate cell configuration is the first position of the list as the cell with the highest priority, the second one in the list as the second highest priority and so on. o In another example, the UE selects the cell which has the lowest LTM candidate cell configuration identity (also referred to as LTM candidate configuration index) among the suitable cells for which there exist an LTM candidate cell configuration.

[0082] Seventh rule: The UE selects a suitable cell for which it has established DL synchronization. o A technical advantage may be that the access towards a cell for which the UE has established DL synchronization is faster as it avoids the delay to establish the DL synchronization. o In one example, the UE has been provided a TCI state towards the cell.

[0083] Eighth rule: The UE selects a suitable cell for which it has selected a beam. o A technical advantage may be that this rule speeds up the access as the UE can use a good beam from the beginning, and thus may save power and may increase the likelihood for the failure recovery to succeed. o In one example, the UE has been provided a TCI state towards the cell.

[0084] Ninth rule: The UE selects a suitable cell based on LI measurement reports (e.g., SS-RSRP of an LTM candidate cell which has been reported). o A technical advantage of this rule may be that the UE has knowledge of a recent measurement on the cell and can select a cell with good radio conditions which may speed up the access, may save power and / or may increase the likelihood for the failure recovery to succeed. o In one example, the UE selects a cell for which it sent the latest (e.g., most recent) LI measurement report.

[0085] Tenth rule: The UE selects a suitable cell based on L3 measurements (e.g., cell based RSRP of a cell). A technical advantage of this rule may be that with knowledge of a recent measurement on the cell, the UE can select a cell with good radio conditions which may speed up the access, may save power, and / or may increase the likelihood for the failure recovery to succeed.

[0086] Eleventh rule: The UE selects a suitable cell in lower frequencies or lower frequency range, e.g. FR1. A technical advantage of this rule may be that these cells may have a higher likelihood for failure recovery to succeed than cells on higher frequencies.

[0087] Twelfth rule: The UE selects a suitable cell with “short” SSB periodicity. A technical advantage of this rule may be that it speeds up the access since the delay to wait for the SSB becomes shorter.

[0088] Thirteenth rule: The UE selects the strongest LTM candidate cell out of “N” suitable cells, according to a measurement quantity, wherein a measurement quantity may correspond to RSRP, RSRQ, SINR, etc. o A technical advantage of this rule may be that the UE selects a cell with good radio conditions which may speed up the access, may save power may increase the likelihood for the failure recovery to succeed, and / or may avoid failure or cell change directly after the recovery. o In one sub-example, the measurement quantity is pre-defined (e.g., UE always uses RSRP). o In another example, the UE selects the suitable LTM candidate cell with a strongest measurement quantity (e.g., RSRP), wherein the measurement quantity used is the one which has been configured in the lower layer measurement reports (e.g., set in a report quantity parameter such as reportQuantity). o In another example, this rule is applied unless some other conditions is fulfilled: When there is at least one suitable LTM candidate cell, the UE always selects that one, regardless of the existence of other suitable cells (e.g., which may have better radio conditions, such as RSRP and / or RSRQ). o In a sub-example, the UE first selects one or more LTM candidate cell which are suitable and, among the suitable LTM candidate cells, the UE selects the LTM candidate cell with the highest measurement quantity (e.g., highest RSRP, highest RSRQ, highest SINR, etc.).o In another example, the UE first determines whether there were LTM candidate cells which were suitable (e.g., according to the suitability criteria defined in TS 38.304) and, when there is one cell that is the cell the UE selects; when there are multiple cells, the UE selects the LTM candidate cell with the highest RSRP, RSRQ or SINR, for example. o A technical benefit of such a rule may be that upon a failure, the UE tries to perform an LTM execution first, and, only when there are no suitable LTM candidate cells.

[0089] Fourteenth rule: The UE selects a suitable cell which is controlled by a same network node (e.g., gNB, gNB-DU or gNB-CU) as a network node controlling a PCell in which the radio related failure was detected. A technical advantage of this rule may be that the rule may result in shorter interruption or less data loss compared to selecting a cell that is controlled by a different node, in which case an L2 reset and / or data forwarding may be needed.

[0090] Fifteenth rule: The UE selects a suitable cell which is controlled by a different network node (e.g., gNB, gNB-DU or gNB-CU) than the network node controlling the PCell in which the radio related failure was detected. A technical advantage of this rule may be that the rule may result in faster recovery in case there was a node failure in the network node (e.g., gNB, gNB-DU or gNB-CU) controlling the PCell in which the radio related failure was detected.

[0091] Sixteenth rule: The UE selects a suitable cell towards which an LTM cell switch does not result in an L2 reset (e.g., MAC reset, HARQ reset, RLC re-establishment, PDCP data recovery, or PDCP re-establishment), such as determined by an LTM candidate cell configuration. A technical advantage of this rule may that avoiding L2 reset may result in shorter interruption or less data loss compared to performing L2 reset.

[0092] Seventeenth rule: The UE selects a suitable cell towards which an LTM cell switch would result in lower UE processing delay than other cells that are LTM candidate cells. o In one example, the UE selects a cell for which a LTM candidate cell configuration has already been processed (e.g., the UE has performed a compliance check and generated a complete LTM candidate cell configuration). o In another example, the UE selects a cell for which a LTM candidate cell configuration uses s delta configuration instead of a complete or full configuration.

[0093] Eighteenth rule: The UE selects a suitable cell which is currently configured as an activated secondary cell (SCell). A technical advantage of this rule may be that the UE hasbetter knowledge of the radio conditions of this cell and this may save power, may increase the likelihood for the failure recovery to succeed and / or may avoid failure or cell change directly after the recovery.

[0094] Nineteenth rule: The UE selects a suitable cell in a different frequency than the frequencies for which measurement events are configured. o For example, a different frequency than a frequency where a measurement object for an event (e.g., an A4 event) is configured, o A technical advantage of this rule may be that there is a tendency that the network aims for load balancing for these frequencies. o The frequencies can be the frequencies on which the UE should select the cell first; and, only when there are none available, the UE selects another cell on another frequency, but an LTM candidate cell; a sub-example includes to select the frequency even if there is not a LTM candidate cell in that frequency.

[0095] In some examples, when the UE selects one suitable cell out of multiple suitable cells according to one or more rules, the UE may use a combination of two or more of the rules for the selection of a suitable cell. For example, the UE may select a suitable cell based on a first rule X and a second rule Y, or based on a first rule X, a second rule Y and a third rule Z, and so on. Referring to the rules herein, the UE may, for example, select a cell based on the thirteenth rule as a 1st rule, that is: The UE selects the strongest LTM candidate cell out of “N” suitable cells, for which it has a stored LTM candidate cell configuration, according to a measurement quantity, wherein a measurement quantity may correspond to RSRP, RSRQ, SINR, etc., and the fourth rule as a 2nd rule, that is: The UE selects a suitable cell for which it has a valid TA. In this example, the result of combining these two rules is the following rule: The UE selects the strongest cell out of “N” suitable cells for which it has a valid TA according to a measurement quantity, wherein a measurement quantity may correspond to RSRP, RSRQ, SINR, etc. Corresponding combinations of other rules can be performed that will result in new rules.

[0096] Figure 2 is a sequence diagram of an example in accordance with some embodiments of the present disclosure. In this example, the UE 100 detects a radio related failure, selects a suitable cell out of multiple suitable cells according to one or more rules, and trigger an LTM cell switch towards the selected cell.

[0097] In operation 1, the network 200, 202, 204 prepares LTM candidate cells for the UE 100. One of these cells is the target cell controlled by the target DU 202.

[0098] The serving DU 200, in operations 2-3, configures the UE 100 with LTM candidate cell configurations.

[0099] In operation 4, the UE 100 detects a radio related failure, for example a radio link failure.

[0100] In operation 5, UE 100 selects a suitable cell out of multiple suitable cells according to one or more rules described herein.

[0101] UE 100, in operation 6, determines the selected cell to be an LTM candidate cell (for which the UE 100 has a stored LTM candidate cell configuration).

[0102] In operation 7, UE 100 performs an LTM cell switch towards the selected cell including applying the stored LTM candidate cell configuration associated with the selected cell.

[0103] The target DU 202, in operations 8-9, detects the first UL transmission from the UE 100 and transmits an ACCESS SUCCESS message to the CU 204 to indicate the arrival of the UE 100.

[0104] In operations 10-11, UE 100 transmits an RRCReconfigurationComplete message in the target cell to the target DU 202, which forwards the message to the CU 204.

[0105] Figure 3 is a flow chart of operations of UE performed in accordance with some embodiments.

[0106] A method performed by a UE 100 (configured in accordance with Figure 5 as discussed further herein) is provided. The method includes receiving (operation 300 in Figure 3) a configuration including one or more LTM candidate cell configurations. Each LTM candidate cell configuration is associated to an LTM candidate cell. The method further includes detecting (operation 302 in Figure 3) a radio related failure; and, in response to detecting the radio related failure, selecting (operation 304 in Figure 3) a suitable cell out of multiple suitable cells according to one or more rules. The method further includes, in response to selecting the suitable cell, selectively performing (operation 306 in Figure 3) (i) one or more steps of an LTM cell switch procedure (operation 308) when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration; or (ii) a re-establishment procedure (operation 310 when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with.

[0107] In response to a radio related failure, the UE selects a suitable cell out of multiple suitable cells according to one or more rules. The one or more rules include at least one of selecting a suitable cell in a same frequency as a frequency of the UE’s current primary cell, selecting a suitable cell in a same frequency as a frequency of an LTM candidate cell indicatedin an LTM cell switch command, selecting a suitable cell for which the UE has a valid timing advance, TA, and at the same time is an LTM candidate cell, selecting a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or reselection procedure and at the same time is an LTM candidate cell, selecting a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE, selecting a suitable cell for which the UE has established a downlink, DL, synchronization, selecting a suitable cell based on a LI measurement report, selecting a suitable cell based on a L3 measurement, selecting a suitable cell in a lower frequency or a lower frequency range, selecting a suitable cell with a short synchronization signal block, SSB, periodicity, selecting a strongest LTM candidate cell out of N suitable cells according to a measurement quantity, wherein a measurement quantity corresponds to at least one of a reference signal received power, RSRP, a reference signal received quality, RSRQ, and a signal to interference plus noise ratio, SINR, select a suitable cell that is controlled by a same network node as a network node controlling the PCell in which the radio related failure was detected, select a suitable cell that is controlled by a different network node than a network node controlling the PCell in which the radio related failure was detected, select a suitable cell towards which an LTM cell switch does not result in an L2 reset, select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells, and selecting a suitable cell that is currently configured as an activated secondary cell, SCell, If the selected suitable cell is a LTM candidate cell for which the UE received a LTM candidate cell configuration, the UE performs one or more steps of an LTM cell switch procedure. If the selected suitable cell is a cell that is a cell other than LTM candidate cell for which the UE received a LTM candidate cell configuration, the UE performs a re-establishment procedure.

[0108] In some embodiments the radio related failure comprises a LTM cell switch failure or a supervision timer expiry.

[0109] In some embodiments the multiple suitable cells comprise at least one LTM candidate cell and at least one candidate cell other than a LTM candidate cell. The candidate cell other than the LTM candidate may be a candidate cell for the which the UE has not received a LTM candidate cell configuration.

[0110] In some embodiments, detecting (operation 302) a radio related failure includes at least one of: detecting a while configured with one or more LTM candidate cell configurations; detecting a reconfiguration with synchronization failure or handover failure while configured with one or more LTM candidate cell configurations; detecting an LTM cell switch failurewhile configured with one or more LTM candidate cell configurations; detecting a beam failure detection, BFD, failure while configured with one or more LTM candidate cell configurations (e.g. due to maximum count of beam failure indications (BFIs) from lower layer at the UE received at the MAC entity being reached, as defined in TS 38.321, V17.4.0); and detecting a RLC unrecoverable error (e.g. that the maximum number of retransmissions has been reached for an RLC entity).[OHl] In some embodiments, performing one or more steps of an LTM cell switch procedure (operation 308) when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration further includes applying the stored LTM candidate cell configuration associated with the selected cell.

[0112] In some embodiments, performing a re-establishment procedure (operation 310) when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with further includes transmitting a RRC reestablishment request message to the selected cell and receiving a response message.

[0113] In response to detecting the radio related failure, in some embodiments, the method further includes initiating a re-establishment procedure and starting a timer (e.g. timer T311); and selecting a suitable cell while the timer is running.

[0114] In some embodiments, selecting (operation 304) one suitable cell out of multiple suitable cells is according to one or more rules includes selecting one of the configured LTM candidate cells when there is at least one suitable cell which is an LTM candidate cell among the multiple suitable cells.

[0115] In some embodiments, there is one or more exceptions in which the one or more rules is not applied.

[0116] The one or more exceptions can include at least one ofThe one or more rules is applied except when the at least one suitable LTM candidate cell is not in a same frequency as a PCell in which the radio related failure was detected, or the PCell the UE was coming from when an LTM cell switch failure or handover failure was detected;The one or more rules is applied except when the at least one suitable LTM candidate cell has substantially worse radio conditions than a strongest suitable cell which is not an LTM candidate cell; andThe one or more rules is applied except when the at least one suitable LTM candidate cell is in a frequency which differs from the PCell frequency (e.g. SSB frequency and / or subcarrier spacing) and there is at least one suitable cell which is not an LTM candidatecell in the same frequency as the PCell in a case of a RLF or the same frequency as a source PCell or the same frequency as the LTM candidate cell indicated in a LTM cell switch command in a case of an LTM cell switch failure.

[0117] In some embodiments, there are multiple suitable cells which are LTM candidate cells and the method further includes applying another one or more rules for selecting one of the suitable LTM candidate cells.

[0118] In some embodiments, selecting (operation 304) a suitable cell out of multiple suitable cells according to one or more rules comprises at least one of the following rules: select a suitable cell in a same frequency as a frequency of the UE’s current primary cell; select a suitable cell in a same frequency as a frequency of an LTM candidate cell indicated in an LTM cell switch command; select a suitable cell for which the UE has a valid TA, and at the same time is an LTM candidate cell; select a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or re-selection procedure and at the same time is an LTM candidate cell; select a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE; select a suitable cell for which the UE has established a downlink, DL synchronization; select a suitable cell based on a LI measurement report (e.g. SS-RSRP of an LTM candidate cell which has been reported); select a suitable cell based on a L3 measurement (e.g. cell based RSRP of a cell); select a suitable cell in a lower frequency or a lower frequency range (e.g. FR1); select a suitable cell with a short SSB periodicity; select a strongest LTM candidate cell out of N suitable cells according to a measurement quantity, wherein a measurement quantity corresponds to at least one of RSRP, RSRQ, SINR; select a suitable cell that is controlled by a same network node (e.g. gNB, gNB-DU or gNB-CU) as a network node controlling the PCell in which the radio related failure was detected; select a suitable cell that is controlled by a different network node (e.g. gNB, gNB-DU or gNB-CU) than a network node controlling the PCell in which the radio related failurewas detected; select a suitable cell towards which an LTM cell switch does not result in an L2 reset (e.g. MAC reset, HARQ reset, RLC re-establishment, PDCP data recovery or PDCP reestablishment), such as determined by an LTM candidate cell configuration; select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells; select a suitable cell that is currently configured as an activated SCell; and select a suitable cell in a different frequency than frequencies for which measurement events are configured.

[0119] Some other embodiments are directed to a UE including processing circuitry configured to: receive a configuration including one or more LTM candidate cell configurations. Each LTM candidate cell configuration is associated to an LTM candidate cell. The processing circuitry is further configured to detect a radio related failure; and in response to detect the radio related failure, select a suitable cell out of multiple suitable cells according to one or more rules. The processing circuitry is further configured to, in response to select the suitable cell, selectively perform (i) one or more steps of an LTM cell switch procedure when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration; or (ii) a re-establishment procedure when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with

[0120] In response to a radio related failure, the progressing circuitry is configured to select a suitable cell out of multiple suitable cells according to one or more rules. The one or more rules include at least one of selecting a suitable cell in a same frequency as a frequency of the UE’s current primary cell, selecting a suitable cell in a same frequency as a frequency of an LTM candidate cell indicated in an LTM cell switch command, selecting a suitable cell for which the UE has a valid timing advance, TA, and at the same time is an LTM candidate cell, selecting a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or re-selection procedure and at the same time is an LTM candidate cell, selecting a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE, selecting a suitable cell for which the UE has established a downlink, DL, synchronization, selecting a suitable cell based on a LI measurement report, selecting a suitable cell based on a L3 measurement, selecting a suitable cell in a lower frequency or a lower frequency range, selecting a suitable cell with a short synchronization signal block, SSB, periodicity, selecting a strongest LTM candidate cell out of N suitable cells according to a measurement quantity,wherein a measurement quantity corresponds to at least one of a reference signal received power, RSRP, a reference signal received quality, RSRQ, and a signal to interference plus noise ratio, SINR, select a suitable cell that is controlled by a same network node as a network node controlling the PCell in which the radio related failure was detected, select a suitable cell that is controlled by a different network node than a network node controlling the PCell in which the radio related failure was detected, select a suitable cell towards which an LTM cell switch does not result in an L2 reset, select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells, and selecting a suitable cell that is currently configured as an activated secondary cell, SCell, If the selected suitable cell is a LTM candidate cell for which the UE received a LTM candidate cell configuration, the processing circuitry is configured to perform one or more steps of an LTM cell switch procedure. If the selected suitable cell is a cell that is a cell other than LTM candidate cell for which the UE received a LTM candidate cell configuration, the processing circuitry is configured to perform a re-establishment procedure.

[0121]

[0122] In some embodiments, the processing circuitry of the UE is further configured to perform any of the methods described above as being implementable by a UE.

[0123] Some other embodiments are directed to a UE including an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to: receive a configuration including one or more LTM candidate cell configurations. Each LTM candidate cell configuration is associated to an LTM candidate cell; detect a radio related failure; in response to detect the radio related failure, select a suitable cell out of multiple suitable cells according to one or more rules; and in response to select the suitable cell, selectively perform(i) one or more steps of an LTM cell switch procedure when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration; or(ii) a re-establishment procedure when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with. The UE further includes an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

[0124] In some embodiments, the processing circuitry of the UE is further configured to perform any of the methods described above as being implementable by a UE.

[0125] Yet other embodiments are directed to a method implemented by a host operating in a communication system that further includes a network node and a UE. The method includes providing user data for the UE; and initiating a transmission carrying the user data to the UE via a cellular network comprising the network node. The UE performs the following operations to receive the user data from the host: receiving a configuration including one or more LTM candidate cell configurations. Each LTM candidate cell configuration is associated to an LTM candidate cell; detecting a radio related failure; in response to detecting the radio related failure, selecting (304) a suitable cell out of multiple suitable cells according to one or more rules; and in response to selecting the suitable cell, selectively performing (306) (i) one or more steps of an LTM cell switch procedure (308) when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration; or (ii) a re-establishment procedure (310) when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with.

[0126] In some embodiments, the method implemented by the host further includes performing any of the methods described above as being implementable a host.

[0127] Some other embodiments are directed to a host configured to operate in a communication system to provide an over-the-top, OTT, service. The host includes processing circuitry configured to provide user data, and a network interface configured to initiate transmissions of the user data to a cellular network for transmission to a UE. The UE includes a communication interface and processing circuitry. The communication interface and processing circuitry of the UE being configured to perform the following operations to receive the user data from the host: receive a configuration including one or more LTM candidate cell configurations. Each LTM candidate cell configuration is associated to an LTM candidate cell; detect a radio related failure; in response to detect the radio related failure, select a suitable cell out of multiple suitable cells according to one or more rules; and in response to select the suitable cell, selectively perform (i) one or more steps of an LTM cell switch procedure when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration; or (ii) a re-establishment procedure when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with.

[0128] In some further embodiments, the processing circuitry of the host is further configured to perform any of the methods described above as being implementable by a host.

[0129] Figure 4 shows an example of a communication system QQ100 in accordance with some embodiments.

[0130] In the example, the communication system QQ100 includes a telecommunication network QQ102 that includes an access network QQ104, such as a RAN, and a core network QQ106, which includes one or more core network nodes QQ108. The access network QQ104 includes one or more access network nodes, such as network nodes QQ110a and QQ110b (one or more of which may be generally referred to as network nodes QQ110), or any other similar 3GPP access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node 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 telecommunication network QQ102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network QQ102 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 nodes to implement one or more functionalities of any node in the telecommunication network QQ102, including one or more network nodes QQ110 and / or core network nodes QQ108.

[0131] 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). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) 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 O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes QQ 110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs QQ112a, QQ112b, QQ112c, and QQ112d (one or more of which maybe generally referred to as UEs QQ112) to the core network QQ106 over one or more wireless connections.

[0132] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system QQ100 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system QQ100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0133] The UEs QQ112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes QQ110 and other communication devices. Similarly, the network nodes QQ110 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs QQ112 and / or with other network nodes or equipment in the telecommunication network QQ102 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network QQ102.

[0134] In the depicted example, the core network QQ106 connects the network nodes QQ110 to one or more hosts, such as host QQ116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network QQ106 includes one more core network nodes (e.g., core network node QQ108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node QQ108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0135] The host QQ116 may be under the ownership or control of a service provider other than an operator or provider of the access network QQ104 and / or the telecommunication network QQ102, and may be operated by the service provider or on behalf of the service provider. The host QQ116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0136] As a whole, the communication system QQ100 of Figure 4 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0137] In some examples, the telecommunication network QQ102 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network QQ102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network QQ102. For example, the telecommunications network QQ102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0138] In some examples, the UEs QQ112 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network QQ104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network QQ104. Additionally, a UE may be configured for operating in single- or multi-RAT or multi -standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio)and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN- DC).

[0139] In the example, the hub QQ114 communicates with the access network QQ104 to facilitate indirect communication between one or more UEs (e.g., UE QQ112c and / or QQ112d) and network nodes (e.g., network node QQ110b). In some examples, the hub QQ114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub QQ114 may be a broadband router enabling access to the core network QQ106 for the UEs. As another example, the hub QQ114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes QQ110, or by executable code, script, process, or other instructions in the hub QQ114. As another example, the hub QQ114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub QQ114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub QQ114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub QQ114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub QQ114 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0140] The hub QQ114 may have a constant / persistent or intermittent connection to the network node QQ110b. The hub QQ114 may also allow for a different communication scheme and / or schedule between the hub QQ114 and UEs (e.g., UE QQ112c and / or QQ112d), and between the hub QQ114 and the core network QQ106. In other examples, the hub QQ114 is connected to the core network QQ106 and / or one or more UEs via a wired connection. Moreover, the hub QQ114 may be configured to connect to an M2M service provider over the access network QQ104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes QQ110 while still connected via the hub QQ114 via a wired or wireless connection. In some embodiments, the hub QQ114 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node QQ110b. In other embodiments, the hub QQ114 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node QQ110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0141] Figure 5 shows a UE QQ200 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0142] A UE may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle- to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0143] The UE QQ200 includes processing circuitry QQ202 that is operatively coupled via a bus QQ204 to an input / output interface QQ206, a power source QQ208, a memory QQ210, a communication interface QQ212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 5. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0144] The processing circuitry QQ202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory QQ210. The processing circuitry QQ202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or morestored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry QQ202 may include multiple central processing units (CPUs).

[0145] In the example, the input / output interface QQ206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE QQ200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0146] In some embodiments, the power source QQ208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source QQ208 may further include power circuitry for delivering power from the power source QQ208 itself, and / or an external power source, to the various parts of the UE QQ200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source QQ208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source QQ208 to make the power suitable for the respective components of the UE QQ200 to which power is supplied.

[0147] The memory QQ210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory QQ210 includes one or more application programs QQ214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data QQ216. Thememory QQ210 may store, for use by the UE QQ200, any of a variety of various operating systems or combinations of operating systems.

[0148] The memory QQ210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory QQ210 may allow the UE QQ200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory QQ210, which may be or comprise a device-readable storage medium.

[0149] The processing circuitry QQ202 may be configured to communicate with an access network or other network using the communication interface QQ212. The communication interface QQ212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna QQ222. The communication interface QQ212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter QQ218 and / or a receiver QQ220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter QQ218 and receiver QQ220 may be coupled to one or more antennas (e.g., antenna QQ222) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0150] In the illustrated embodiment, communication functions of the communication interface QQ212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may beimplemented in according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0151] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface QQ212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0152] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0153] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE inthe form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE QQ200 shown in Figure 5.

[0154] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0155] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0156] Figure 6 shows a network node QQ300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR. NodeBs (gNBs)), 0-RAN nodes or components of an 0-RAN node (e.g, 0-RU, 0-DU, O-CU).

[0157] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an 0-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio.Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0158] Other examples of network nodes include multiple transmission point (multi-TRP)5G access nodes, multi -standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0159] The network node QQ300 includes a processing circuitry QQ302, a memory QQ304, a communication interface QQ306, and a power source QQ308. The network node QQ300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node QQ300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeB s. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node QQ300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory QQ304 for different RATs) and some components may be reused (e.g., a same antenna QQ310 may be shared by different RATs). The network node QQ300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node QQ300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node QQ300.

[0160] The processing circuitry QQ302 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 QQ300 components, such as the memory QQ304, to provide network node QQ300 functionality.

[0161] In some embodiments, the processing circuitry QQ302 includes a system on a chip (SOC). In some embodiments, the processing circuitry QQ302 includes one or more of radio frequency (RF) transceiver circuitry QQ312 and baseband processing circuitry QQ314. In some embodiments, the radio frequency (RF) transceiver circuitry QQ312 and the baseband processing circuitry QQ314 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 QQ312 and baseband processing circuitry QQ314 may be on the same chip or set of chips, boards, or units.

[0162] The memory QQ304 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 the processing circuitry QQ302. The memory QQ304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry QQ302 and utilized by the network node QQ300. The memory QQ304 may be used to store any calculations made by the processing circuitry QQ302 and / or any data received via the communication interface QQ306. In some embodiments, the processing circuitry QQ302 and memory QQ304 is integrated.

[0163] The communication interface QQ306 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface QQ306 comprises port(s) / terminal(s) QQ316 to send and receive data, for example to and from a network over a wired connection. The communication interface QQ306 also includes radio front-end circuitry QQ318 that may be coupled to, or in certain embodiments a part of, the antenna QQ310. Radio front-end circuitry QQ318 comprises filters QQ320 and amplifiers QQ322. The radio front-end circuitry QQ318 may be connected to an antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry may be configured to condition signals communicated between antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry QQ318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry QQ318 may convert the digital data into a radio signal having the appropriate channel andbandwidth parameters using a combination of filters QQ320 and / or amplifiers QQ322. The radio signal may then be transmitted via the antenna QQ310. Similarly, when receiving data, the antenna QQ310 may collect radio signals which are then converted into digital data by the radio front-end circuitry QQ318. The digital data may be passed to the processing circuitry QQ302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0164] In certain alternative embodiments, the network node QQ300 does not include separate radio front-end circuitry QQ318, instead, the processing circuitry QQ302 includes radio front-end circuitry and is connected to the antenna QQ310. Similarly, in some embodiments, all or some of the RF transceiver circuitry QQ312 is part of the communication interface QQ306. In still other embodiments, the communication interface QQ306 includes one or more ports or terminals QQ316, the radio front-end circuitry QQ318, and the RF transceiver circuitry QQ312, as part of a radio unit (not shown), and the communication interface QQ306 communicates with the baseband processing circuitry QQ314, which is part of a digital unit (not shown).

[0165] The antenna QQ310 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna QQ310 may be coupled to the radio front-end circuitry QQ318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna QQ310 is separate from the network node QQ300 and connectable to the network node QQ300 through an interface or port.

[0166] The antenna QQ310, communication interface QQ306, and / or the processing circuitry QQ302 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna QQ310, the communication interface QQ306, and / or the processing circuitry QQ302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0167] The power source QQ308 provides power to the various components of network node QQ300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source QQ308 may further comprise, or be coupled to, power management circuitry to supply the components of the network nodeQQ300 with power for performing the functionality described herein. For example, the network node QQ300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source QQ308. As a further example, the power source QQ308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0168] Embodiments of the network node QQ300 may include additional components beyond those shown in Figure 6 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node QQ300 may include user interface equipment to allow input of information into the network node QQ300 and to allow output of information from the network node QQ300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node QQ300.

[0169] Figure 7 is a block diagram of a host QQ400, which may be an embodiment of the host QQ116 of Figure 4, in accordance with various aspects described herein. As used herein, the host QQ400 may be or comprise various combinations hardware and / or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host QQ400 may provide one or more services to one or more UEs.

[0170] The host QQ400 includes processing circuitry QQ402 that is operatively coupled via a bus QQ404 to an input / output interface QQ406, a network interface QQ408, a power source QQ410, and a memory QQ412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures QQ2 and QQ3, such that the descriptions thereof are generally applicable to the corresponding components of host QQ400.

[0171] The memory QQ412 may include one or more computer programs including one or more host application programs QQ414 and data QQ416, which may include user data, e.g., data generated by a UE for the host QQ400 or data generated by the host QQ400 for a UE. Embodiments of the host QQ400 may utilize only a subset or all of the components shown. The host application programs QQ414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audiocodecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs QQ414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host QQ400 may select and / or indicate a different host for over-the-top services for a UE. The host application programs QQ414 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

[0172] Figure 8 is a block diagram illustrating a virtualization environment QQ500 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments QQ500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment QQ500 includes components defined by the 0-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0173] Applications QQ502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0174] Hardware QQ504 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers QQ506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMsQQ508a and QQ508b (one or more of which may be generally referred to as VMs QQ508), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer QQ506 may present a virtual operating platform that appears like networking hardware to the VMs QQ508.

[0175] The VMs QQ508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer QQ506. Different embodiments of the instance of a virtual appliance QQ502 may be implemented on one or more of VMs QQ508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0176] In the context of NFV, a VM QQ508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs QQ508, and that part of hardware QQ504 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs QQ508 on top of the hardware QQ504 and corresponds to the application QQ502.

[0177] Hardware QQ504 may be implemented in a standalone network node with generic or specific components. Hardware QQ504 may implement some functions via virtualization. Alternatively, hardware QQ504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration QQ510, which, among others, oversees lifecycle management of applications QQ502. In some embodiments, hardware QQ504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system QQ512 which may alternatively be used for communication between hardware nodes and radio units.

[0178] Figure 9 shows a communication diagram of a host QQ602 communicating via a network node QQ604 with a UE QQ606 over a partially wireless connection in accordancewith some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE QQ112a of Figure 4 and / or UE QQ200 of Figure 5), network node (such as network node QQ110a of Figure 4 and / or network node QQ300 of Figure 6), and host (such as host QQ116 of Figure 4 and / or host QQ400 of Figure 7) discussed in the preceding paragraphs will now be described with reference to Figure 9.

[0179] Like host QQ400, embodiments of host QQ602 include hardware, such as a communication interface, processing circuitry, and memory. The host QQ602 also includes software, which is stored in or accessible by the host QQ602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE QQ606 connecting via an over-the-top (OTT) connection QQ650 extending between the LTE QQ606 and host QQ602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection QQ650.

[0180] The network node QQ604 includes hardware enabling it to communicate with the host QQ602 and UE QQ606. The connection QQ660 may be direct or pass through a core network (like core network QQ106 of Figure 4) and / or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

[0181] The UE QQ606 includes hardware and software, which is stored in or accessible by UE QQ606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE QQ606 with the support of the host QQ602. In the host QQ602, an executing host application may communicate with the executing client application via the OTT connection QQ650 terminating at the UE QQ606 and host QQ602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection QQ650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection QQ650.

[0182] The OTT connection QQ650 may extend via a connection QQ660 between the host QQ602 and the network node QQ604 and via a wireless connection QQ670 between the network node QQ604 and the UE QQ606 to provide the connection between the host QQ602 and the UE QQ606. The connection QQ660 and wireless connection QQ670, over which the OTT connection QQ650 may be provided, have been drawn abstractly to illustrate thecommunication between the host QQ602 and the UE QQ606 via the network node QQ604, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0183] As an example of transmitting data via the OTT connection QQ650, in step QQ608, the host QQ602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE QQ606. In other embodiments, the user data is associated with a UE QQ606 that shares data with the host QQ602 without explicit human interaction. In step QQ610, the host QQ602 initiates a transmission carrying the user data towards the UE QQ606. The host QQ602 may initiate the transmission responsive to a request transmitted by the UE QQ606. The request may be caused by human interaction with the UE QQ606 or by operation of the client application executing on the UE QQ606. The transmission may pass via the network node QQ604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step QQ612, the network node QQ604 transmits to the UE QQ606 the user data that was carried in the transmission that the host QQ602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step QQ614, the UE QQ606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE QQ606 associated with the host application executed by the host QQ602.

[0184] In some examples, the UE QQ606 executes a client application which provides user data to the host QQ602. The user data may be provided in reaction or response to the data received from the host QQ602. Accordingly, in step QQ616, the UE QQ606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input / output interface of the UE QQ606. Regardless of the specific manner in which the user data was provided, the UE QQ606 initiates, in step QQ618, transmission of the user data towards the host QQ602 via the network node QQ604. In step QQ620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node QQ604 receives user data from the UE QQ606 and initiates transmission of the received user data towards the host QQ602. In step QQ622, the host QQ602 receives the user data carried in the transmission initiated by the UE QQ606.

[0185] One or more of the various embodiments improve the performance of OTT services provided to the UE QQ606 using the OTT connection QQ650, in which the wireless connection QQ670 forms the last segment. More precisely, the teachings of these embodiments mayimprove the reduce signaling and / or prevent a handover or LTM cell switch command and thereby provide benefits such as saving power / energy at the UE, and / or prevent an interruption time and service disruption.

[0186] In an example scenario, factory status information may be collected and analyzed by the host QQ602. As another example, the host QQ602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host QQ602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host QQ602 may store surveillance video uploaded by a UE. As another example, the host QQ602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host QQ602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0187] In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection QQ650 between the host QQ602 and UE QQ606, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host QQ602 and / or UE QQ606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection QQ650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection QQ650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node QQ604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host QQ602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection QQ650 while monitoring propagation times, errors, etc.

[0188] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information 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. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0189] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer- readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

Claims

CLAIMS1. A method performed by a user equipment, UE, the method comprising: receiving (300) a configuration including one or more L1 / L2 triggered mobility, LTM, candidate cell configurations, wherein each LTM candidate cell configuration is associated to an LTM candidate cell; in response to a radio related failure, selecting (304) a suitable cell out of multiple suitable cells according to one or more rules; in response to the selected suitable cell being a LTM candidate cell for which the UE received a LTM candidate cell configuration, performing (306) one or more steps of an LTM cell switch procedure (308); and, in response to the selected suitable cell being a cell other than a LTM candidate cell for which the UE received a LTM candidate cell configuration, performing a re-establishment procedure (310); wherein the selecting (304) a suitable cell out of multiple suitable cells according to one or more rules comprises at least one of the following rules: select a suitable cell in a same frequency as a frequency of the UE’s current primary cell, select a suitable cell in a same frequency as a frequency of an LTM candidate cell indicated in an LTM cell switch command, select a suitable cell for which the UE has a valid timing advance, TA, and at the same time is an LTM candidate cell, select a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or re-selection procedure and at the same time is an LTM candidate cell, select a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE, select a suitable cell for which the UE has established a downlink, DL, synchronization, select a suitable cell based on a LI measurement report, select a suitable cell based on a L3 measurement, select a suitable cell in a lower frequency or a lower frequency range, select a suitable cell with a short synchronization signal block, SSB, periodicity,select a strongest LTM candidate cell out of N suitable cells according to a measurement quantity, wherein a measurement quantity corresponds to at least one of a reference signal received power, RSRP, a reference signal received quality, RSRQ, and a signal to interference plus noise ratio, SINR. select a suitable cell that is controlled by a same network node as a network node controlling the PCell in which the radio related failure was detected, select a suitable cell that is controlled by a different network node than a network node controlling the PCell in which the radio related failure was detected, select a suitable cell towards which an LTM cell switch does not result in an L2 reset, select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells, select a suitable cell that is currently configured as an activated secondary cell, SCell, and select a suitable cell in a different frequency than frequencies for which measurement events are configured.

2. The method of claim 1, wherein the method further comprises: detecting (302) a radio related failure.

3. The method of claim 2, wherein the radio related failure comprises a LTM cell switch failure or a supervision timer expiry.

4. The method of any of claims 1-3, wherein the multiple suitable cells comprise at least one LTM candidate cell and at least one candidate cell other than a LTM candidate cell.

5. The method of any of claims 1-4, wherein a suitable cell is a cell on which the UE can camp.

6. The method of any of claims 1-5, wherein the detecting a radio related failure comprises at least one of detecting a radio link failure, RLF, while configured with one or more LTM candidate cell configurations, detecting a reconfiguration with synchronization failure or handover failure while configured with one or more LTM candidate cell configurations,detecting an LTM cell switch failure while configured with one or more LTM candidate cell configurations, detecting a beam failure detection, BF, failure while configured with one or more LTM candidate cell configurations, and detecting a radio link control, RLC, unrecoverable error.

7. The method of claim 1, wherein the performing one or more steps of an LTM cell switch procedure (308) when the selected cell is determined to be a LTM candidate cell for which the UE has a stored LTM candidate cell configuration further comprises applying the stored LTM candidate cell configuration associated with the selected cell.

8. The method of claim 1, wherein the performing a re-establishment procedure (310) when the selected cell is determined to be a cell which is not an LTM candidate cell the UE is configured with further comprises transmitting a radio resource control, RRC, reestablishment request message to the selected cell and receiving a response message.

9. The method of claim 1, wherein in response to detecting the radio related failure, the method further comprises: initiating a re-establishment procedure and starting a timer; and selecting a suitable cell while the timer is running.

10. The method of claim 1, wherein the selecting (304) one suitable cell out of multiple suitable cells is according to one or more rules comprises selecting one of the configured LTM candidate cells when there is at least one suitable cell which is an LTM candidate cell among the multiple suitable cells.

11. The method of claim 10, wherein there is one or more exceptions in which the one or more rules is not applied.

12. The method of claim 11, wherein the one or more exceptions comprise at least one of: the one or more rules is applied except when the at least one suitable LTM candidate cell is not in a same frequency as a primary cell, PCell, in which the radio related failurewas detected, or the PCell the UE was coming from when an LTM cell switch failure or handover failure was detected, the one or more rules is applied except when the at least one suitable LTM candidate cell has substantially worse radio conditions than a strongest suitable cell which is not an LTM candidate cell, and the one or more rules is applied except when the at least one suitable LTM candidate cell is in a frequency which differs from the PCell frequency and there is at least one suitable cell which is not an LTM candidate cell in the same frequency as the PCell in a case of a RLF or the same frequency as a source PCell or the same frequency as the LTM candidate cell indicated in a LTM cell switch command in a case of an LTM cell switch failure.

13. The method of claim 10, wherein there are multiple suitable cells which are LTM candidate cells and the method further comprises: applying another one or more rules for selecting one of the suitable LTM candidate cells.

14. A user equipment, UE, (100, QQ112A-QQ112D, QQ200) comprising: processing circuitry (QQ202) configured to: receive a configuration including one or more L1 / L2 triggered mobility, LTM, candidate cell configurations, wherein each LTM candidate cell configuration is associated to an LTM candidate cell; in response to a radio related failure, select a suitable cell out of multiple suitable cells according to one or more rules; in response to the selected suitable cell being a LTM candidate cell for which the UE received a LTM candidate cell configuration, perform (i) one or more steps of an LTM cell switch procedure; and, in response to the selected suitable cell being a cell other than a LTM candidate cell for which the UE received a LTM candidate cell configuration perform a reestablishment procedure, wherein the selecting a suitable cell out of multiple suitable cells according to one or more rules comprises at least one of the following rules: select a suitable cell in a same frequency as a frequency of the UE’s current primary cell,select a suitable cell in a same frequency as a frequency of an LTM candidate cell indicated in an LTM cell switch command, select a suitable cell for which the UE has a valid timing advance, TA, and at the same time is an LTM candidate cell, select a suitable cell whose frequency is part of a configuration provided to the UE for performing a cell selection or re-selection procedure and at the same time is an LTM candidate cell, select a suitable cell for which an LTM candidate configuration is available and further select the cell based on the order in which the LTM candidate configuration is provided to the UE, select a suitable cell for which the UE has established a downlink, DL, synchronization, select a suitable cell based on a LI measurement report, select a suitable cell based on a L3 measurement, select a suitable cell in a lower frequency or a lower frequency range, select a suitable cell with a short synchronization signal block, SSB, periodicity, select a strongest LTM candidate cell out of N suitable cells according to a measurement quantity, wherein a measurement quantity corresponds to at least one of a reference signal received power, RSRP, a reference signal received quality, RSRQ, and a signal to interference plus noise ratio, SINR. select a suitable cell that is controlled by a same network node as a network node controlling the PCell in which the radio related failure was detected, select a suitable cell that is controlled by a different network node than a network node controlling the PCell in which the radio related failure was detected, select a suitable cell towards which an LTM cell switch does not result in an L2 reset, select a suitable cell towards which an LTM cell switch that results in a lower UE processing delay than other cells that are LTM candidate cells, select a suitable cell that is currently configured as an activated secondary cell, SCell, and select a suitable cell in a different frequency than frequencies for which measurement events are configured.

15. The UE of claim 14, wherein the processing circuitry (QQ202) is further configured to perform the method of any of Claims 2 to 13.

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