Successful LTM cell switch report

Abstract

Methods and apparatuses for reporting a successful Layer 1 / Layer 2 – triggered mobility, LTM, cell switch An example method performed by a user equipment, UE, comprises determining (510) that a LTM cell switch triggered by an LTM cell switch command has been successfully executed. Upon determining that the execution of the LTM cell switch is successful, the UE logs (512) information related to the successful execution of the LTM cell switch. The UE transmits (520) a successful LTM cell switch report to a network node. The LTM cell switch report includes the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

Description

[0001] SUCCESSFUL LTM CELL SWITCH REPORT

[0002] TECHNICAL FIELD

[0003] The present application relates generally to the field of wireless networks, and more specifically to improving mobility of user equipment (UEs) across multiple cells in a wireless network, specifically mobility based on layer-1 (LI) and / or layer-2 (L2) procedures that incur less delay than conventional layer-3 mobility procedures.

[0004] BACKGROUND

[0005] Currently the fifth generation (5G) of cellular systems is being standardized within the Third- Generation Partnership Project (3GPP). NR is developed for maximum flexibility to support multiple and substantially different use cases. These include enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), side-link device-to- device (D2D), and several other use cases.

[0006] Figure 1 illustrates a high-level view of an exemplary 5G network architecture, consisting of a Next Generation Radio Access Network (NG-RAN, 199) and a 5G Core (5GC, 198). The NG-RAN can include one or more gNodeBs (gNBs) connected to the 5GC via one or more NG interfaces, such as gNBs (100, 150) connected via respective interfaces (102, 152). More specifically, the gNBs can be connected to one or more Access and Mobility Management Functions (AMFs) in the 5GC via respective NG-C interfaces and to one or more User Plane Functions (UPFs) in 5GC via respective NG- U interfaces. The 5GC can include various other network functions (NFs), such as Session Management Function(s) (SMF).

[0007] Figure 2 shows an exemplary configuration of NR user plane (UP) and control plane (CP) protocol stacks.

[0008] Although not shown in Figure 1, in some deployments the 5GC can be replaced by an Evolved Packet Core (EPC), which conventionally has been used together with a fourth generation (4G) Long-Term Evolution (LTE) Evolved UMTS RAN (E-UTRAN). In such deployments, gNBs (e.g., 100, 150) can connect to one or more Mobility Management Entities (MMEs) in EPC 198 via respective Sl-C interfaces. Similarly, gNBs can connect to one or more Serving Gateways (SGWs) in EPC via respective NG-U interfaces.

[0009] In addition, the gNBs can be connected to each other via one or more Xn interfaces, such as Xn interface (140) between gNBs (100, 150). The radio technology for the NG-RAN is often referred to as "New Radio" (NR). With respect to the NR interface to UEs, each of the gNBs can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each of the gNBs can serve a geographic coverage area including one or more cells and, in some cases, can also use various directional beams to provide coverage in the respective cells. In general, a DL "beam" is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE.

[0010] NG RAN logical nodes (e.g., gNB 100) include a Central Unit (CU or gNB-CU, e.g., 110) and one or more Distributed Units (DU or gNB-DU, e.g., 120, 130). CUs are logical nodes that host higher-layer protocols and perform various gNB functions such controlling the operation of DUs. DUs are decentralized logical nodes that host lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. Each CU and DU can include various circuitry needed to perform their respective functions, including processing circuitry, communication interface circuitry (e.g., transceivers), and power supply circuitry.

[0011] A gNB-CU connects to one or more gNB-DUs over respective Fl logical interfaces (e.g., 122 and 132 shown in Figure 1). However, a gNB-DU can be connected to only a single gNB-CU. The gNB-CU and its connected gNB-DU(s) are only visible to other gNBs and the 5GC as a gNB. In other words, the Fl interface is not visible beyond gNB-CU.

[0012] Seamless handovers are a key feature of 3GPP technologies. A UE is handed over from a source or serving cell, provided by a source node, to a target cell provided by a target node. Successful handovers ensure that the UE moves around in the coverage area of different cells without causing too many interruptions in the data transmission. However, handover can have various problems related to robustness. For example, a handover command (e.g., RRCReconfiguration message including a reconfigurationWithSync information element) is normally sent when the radio conditions for the UE are already quite bad and may not reach the UE before the UE's degraded connection with the source node / cell is dropped.

[0013] Upon receiving a handover command, a UE starts a timer T304 to monitor whether the handover is successful. Upon T304 expiry the UE considers the handover failed and performs recovery actions such as initiation of an RRC Re-establishment procedure including cell selection while another timer T311 is running. While T304 is running, the UE's radio resource control (RRC) layer triggers a randomaccess (RA) procedure with a target cell indicated in the reconfigurationWithSync IE. The handover is considered successful when the RA procedure is successfully completed before T304 expiry. The reconfiguration with sync procedure during handover is further defined in 3GPP TS 38.331 (vl7.2.0) section 5.3.5.5.2. A RACH-less handover was specified for LTE in 3GPP Rel-14. If the UE receives a handover command with a rach-Skip field, the UE should perform the handover to the target cell without performing a RA procedure. The UE initiates T304 in a similar manner as described above, but the handover is considered successful if the UE successfully receives certain information from the network via the target cell indicated in the handover command.

[0014] When the UE moves between the coverage areas of two cells, a serving cell change needs to be performed at some point. Currently, serving cell change is triggered by layer 3 (L3, e.g., RRC) measurements and involves RRC signaling to change PCell and / or PSCell (e.g., when dual connectivity is configured), as well as release / add SCells (e.g., when CA is configured). Currently, L3 inter-cell mobility involves complete layer 2 (L2) and layer 1 (LI, i.e., PHY) resets, leading to longer latency, increased signaling overhead, and longer interruptions than for intra-cell beam switching.

[0015] Layer 1 / Layer 2 (Ll / L2)-Triggered Mobility (LTM) in 3GPP Rel-18

[0016] Layer 1 / Layer 2-Triggered Mobility (LTM) has been specified in Release 18 of the 3GPP specifications as part of the Mobility enhancements Work Item. According to a version of the running change request (CR) for 3GPP TS 38.300, LTM is a procedure in which a gNB receives LI measurement report(s) from a UE and, on their basis, changes UE's serving cell using a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate cell configuration that the gNB previously prepared and provided to the UE through RRC signalling. Upon receipt of the command, the UE switches to the target cell, according to the cell switch command. The LTM procedure can be used to reduce mobility latency.

[0017] LTM supports both intra-gNB-DU and intra-gNB-CU / inter-gNB-DU mobility. LTM supports both intrafrequency and inter-frequency mobility, including mobility to an inter-frequency cell that is not a current serving cell.

[0018] Figure 3 illustrates the signaling procedure for LTM.

[0019] The steps shown in the procedure illustrated in Figure 3 are as follows:

[0020] 1. The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates candidate cell(s) preparation.

[0021] 2. The gNB transmits an RRCReconfiguration message to the UE including the LTM candidate cell configurations of one or multiple candidate cells.

[0022] 3. The UE stores the LTM candidate cell configurations and transmits an RRCReconfigurationComplete message to the gNB. 4a. The UE performs DL synchronization with the candidate cell(s) before receiving the cell switch command.

[0023] 4b. When UE-based TA measurement is configured, UE acquires the TA value(s) of the candidate cell(s) by measurement. Otherwise, UE performs early TA acquisition with the candidate cell (s) as requested by the network before receiving the cell switch command as specified in clause 9.2.6. This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell (s), the UE doesn't receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE doesn't maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.

[0024] 5. The UE performs LI measurements on the configured candidate cell(s) and transmits LI measurement reports to the gNB. LI measurement should be performed as long as RRC reconfiguration(step 2) is applicable.

[0025] 6. The gNB decides to execute cell switch to a target cell and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index.

[0026] 7. The UE performs the random access procedure towards the target cell, if UE does not have valid TA of the target cell. The UE performs CFRA if the LTM cell switch command MAC CE contains information for CFRA as specified in clause 6.1.3.xy of TS 38.321[6],

[0027] 8. The UE completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the UE has performed a RA procedure in step 7 the UE considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data. The UE determines successful reception of its first UL data by receiving a PDCCH addressing the UE's C-RNTI in the target cell, which schedules a new transmission following the first UL data. The PDCCH carries either a DL assignment or an UL grant addressing the same HARQ process as the first UL data.

[0028] Self-Organizing Networks (SON) in 3GPP

[0029] A Self-Organizing Network (SON) is an automation technology designed to make the planning, configuration, management, optimization and healing of mobile radio access networks simpler and faster. SON functionality and behavior has been defined and specified in generally accepted mobile industry recommendations produced by organizations such as 3GPP (3rd Generation Partnership Project) and the NGMN (Next Generation Mobile Networks).

[0030] In 3GPP, the processes within the SON area are classified into Self-configuration process and Selfoptimization process. Self-configuration process is the process where newly deployed nodes are configured by automatic installation procedures to get the necessary basic configuration for system operation.

[0031] This process works in pre-operational state. Pre-operational state is understood as the state from when the eNB is powered up and has backbone connectivity until the RF transmitter is switched on.

[0032] As illustrated in Figure 4, functions handled in the pre-operational state, such as basic setup and initial radio configuration, are covered by the Self Configuration process.

[0033] Self-optimization process is defined as the process where UE and access node measurements and performance measurements are used to auto-tune the network. This process works in operational state. Operational state is understood as the state where the RF interface is additionally switched on. As shown in Figure 4, functions handled in the operational state such as Optimization / Adaptation are covered by the Self Optimization process.

[0034] In LTE, support for Self-Configuration and Self-Optimization is specified, as described in 3GPP TS 36.300 section 22.2, including features such as Dynamic configuration, Automatic Neighbour Relation (ANR), Mobility load balancing, Mobility Robustness Optimization (MRO), RACH optimization and support for energy saving.

[0035] In NR, support for Self-Configuration and Self-Optimization is specified as well, starting with SelfConfiguration features such as Dynamic configuration, Automatic Neighbour Relation (ANR) in Rel-15, as described in 3GPP TS 38.300 section 15. In NR Rel-16, more SON features are being specified, including Self-Optimization features such as Mobility Robustness Optimization (MRO).

[0036] Mobility Robustness Optimization (MRO) in 3GPP

[0037] Seamless handovers are a key feature of 3GPP technologies. Successful handovers ensure that the UE moves around in the coverage area of different cells without causing too much interruptions in the data transmission. However, there will be scenarios when the network fails to handover the UE to the 'correct' neighbor cell in time and in such scenarios the UE will declare a radio link failure (RLF) or Handover Failure (HOF). Upon HOF and RLF, the UE may take autonomous actions, i.e., trying to select a cell and initiate reestablishment procedure, so that it can be reachable again. An RLF will cause a poor user experience, as the RLF is declared by the UE only when it realizes that there is no reliable communication channel (radio link) available between itself and the network. Also, reestablishing the connection requires signaling with the newly selected cell (random access procedure, RRC Reestablishment Request, RRC Reestablishment RRC Reestablishment Complete, RRC Reconfiguration and RRC Reconfiguration Complete) and adds some latency, until the UE can exchange data with the network again.

[0038] According to the specifications (3GPP TS 36.331), possible causes for the radio link failure could be one of the following:

[0039] 1) Expiry of the radio link monitoring related timer T310;

[0040] 2) Expiry of the measurement reporting associated timer T312 (not receiving the handover command from the network within this timer's duration despite sending the measurement report when T310 was running);

[0041] 3) Upon reaching the maximum number of RLC retransmissions;

[0042] 4) Upon receiving random access problem indication from the MAC entity;

[0043] As RLF leads to reestablishment, which degrades performance and user experience, it is in the interest of the network to understand the reasons for RLF and try to optimize mobility related parameters (e.g., trigger conditions of measurement reports) to avoid later RLFs. Before the standardization of MRO related report handling in the network, only the UE was aware of some information, such as how the radio quality looked at the time of RLF, the actual reason for declaring RLF, etc. For the network to identify the reason for the RLF, the network needs more information, both from the UE and also from the neighboring base stations.

[0044] As part of the MRO solution in LTE, the RLF reporting procedure was introduced in the RRC specification in Rel-9 RAN2 work. That has impacted the RRC specifications (especially 3GPP TS 36.331) in that it was standardized that the UE would log relevant information at the moment of an RLF and later report to a target cell to which the UE successfully connects (e.g., after reestablishment). That has also impacted the inter-gNodeB interface, i.e., X2AP specifications (3GPP TS 36.423), as an eNodeB receiving an RLF report could forward to the eNodeB where the failure has been originated. For the RLF report generated by the UE, its contents have been enhanced with more details in the subsequent releases. The measurements included in the measurement report based on the latest LTE RRC specification are:

[0045] 1) Measurement quantities (RSRP, RSRQ.) of the last serving cell (PCell).

[0046] 2) Measurement quantities of the neighbor cells in different frequencies of different RATs (EUTRA, UTRA, GERAN, CDMA2000).

[0047] 3) Measurement quantity (RSSI) associated to WLAN Aps.

[0048] 4) Measurement quantity (RSSI) associated to Bluetooth beacons.

[0049] 5) Location information, if available (including location coordinates and velocity)

[0050] 6) Globally unique identity of the last serving cell, if available, otherwise the PCI and the carrier frequency of the last serving cell.

[0051] 7) Tracking area code of the PCell.

[0052] 8) Time elapsed since the last reception of the 'Handover command' message.

[0053] 9) C-RNTI used in the previous serving cell.

[0054] 10) Whether or not the UE was configured with a DRB having QCI value of 1.

[0055] After an RLF is declared, the RLF report is logged and include in the VarRLF-Report and, once the UE selects a cell and succeeds with a reestablishment, it includes an indication that it has an RLF report available in the RRC Reestablishment Complete message, to make the target cell aware of that availability. Then, upon receiving an UElnformationRequest message with a flag "rlf-ReportReq-r9" the UE shall include the RLF report (stored in a UE variable VarRLF-Report, as described above) in an UElnformationResponse message and send it to the network.

[0056] Based on the RLF report from the UE and knowledge about which cell the UE reestablished itself with, the original source cell can deduce whether the RLF was caused due to a coverage hole or due to handover associated parameter configurations. If the RLF was deemed to be due to handover associated parameter configurations, the original serving cell can further classify the handover related failure among too-early, too-late, or handover to wrong cell classes. These handover failure classes are explained in brief below.

[0057] 1) Whether the handover failure occurred due to the 'too-late handover / mobility' cases a. The original serving cell can classify a handover failure to be 'too late handover / mobility' when the original serving cell fails to send the handover command to the UE associated to a handover towards a particular target cell and if the UE reestablishes itself in this target cell post RLF. b. An example corrective action from the original serving cell could be to initiate the handover procedure towards this target cell a bit earlier by decreasing the CIO (cell individual offset) towards the target cell that controls when the IE sends the event triggered measurement report that leads to taking the handover decision.

[0058] 2) Whether the handover failure occurred due to the 'too-early handover / mobility' cases a. The original serving cell can classify a handover failure to be 'too early handover / mobility' when the original serving cell is successful in sending the handover command to the UE associated to a handover however the UE fails to perform the random access towards this target cell or the UE declares RLF in the target cell soon afterwards. b. An example corrective action from the original serving cell could be to initiate the handover procedure towards this target cell a bit later by increasing the CIO (cell individual offset) towards the target cell that controls when the IE sends the event triggered measurement report that leads to taking the handover decision.

[0059] 3) Whether the handover failure occurred due to the 'handover / mobility-to-wrong-cell' cases a. The original serving cell can classify a handover failure to be 'handover / mobility-to- wrong-cell' when the original serving cell intends to perform the handover for this UE towards a particular target cell but the UE declares failure or declares failure shortly after successfully completing the handover and then reestablishes itself in a third cell. b. A corrective action from the original serving cell could be to initiate the measurement reporting procedure that leads to handover towards the target cell a bit later by decreasing the CIO (cell individual offset) towards the target cell or via initiating the handover towards the cell in which the UE reestablished a bit earlier by increasing the CIO towards the reestablishment cell.

[0060] SON and LTM

[0061] SON / MDT Enhancements remains a high priority item for standardization. There is interest in considering, for MRO:

[0062] RO enhancement for R18 mobility mechanisms, Lower layer triggered mobility (LTM), CHO with candidate SCGs, subsequent CPAC [RAN3, RAN2]: o Identify and specify necessary UE reporting to enhance the mobility parameter tuning [RAN2] A goal of LTM cell switch is to reduce latency, overhead and interruption time. The decision to trigger an LTM cell switch procedure is taken by the source DU, while the legacy L3 mobility decisions are taken by the source CU-CP. The LTM candidate cells are expected to be configured in a UE-specific way. A UE might have limitations on how many inter-cell mobility candidates can it keep in the memory (e.g., 8 LTM candidate cells) and thus different UEs in the same DU might be configured with different LTM candidate cells depending on each UE's location, mobility characteristics and other parameters. Further, 3GPP has decided to call L1 / L2 inter-cell mobility with the name of L1 / L2 Triggered Mobility (LTM).

[0063] A SON / MDT work item in Release 19 will comprise data collection for the LTM cell switch procedure, and for the sake of troubleshooting and enhancements the existing SON reports e.g., RLF report or successful handover report, etc., might be enhanced to collect measurements and information for the LTM cell switch procedure.

[0064] Several issues remain.

[0065] SUMMARY

[0066] One problem addressed by this disclosure is that LTM cell switch defines new ways of accessing a target cell, e.g., without random access, with random access, LTM cell switch including a Timing Advance (TA) value in the LTM cell switch command, assumptions regarding UE synchronization in UL and / or DL, TCI state activation / pre-activation, etc. Despite that the LTM cell switch may be successful, there might be different "flavors" of successful LTM cell switch, with different performance impacts in terms of interruption time, resource usage. In some cases, the source cell (e.g., S-DU) that generates the LTM cell switch command may not be fully aware of all the UE actions and conditions at the time of the execution.

[0067] Concerning the successful LTM cell switch procedure, as of now there is no designed solution tailored for the LTM cell switch procedure to collect measurements and information upon successful execution of the LTM cell switch procedure. Improved measurements and information upon success LTM cell switch execution can enable the network to troubleshoot lower layer issues and optimize LTM cell switch procedure.

[0068] One approach to addressing this problem is a method performed by the wireless terminal (a so- called user equipment (UE)), where the method comprises determining that an LTM cell switch triggered by an LTM cell switch command has been successfully executed and logging information related to the successful execution of the LTM cell switch, upon determining that the execution of the LTM cell switch is successful. In some embodiments, the UE may consider the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network. This method further comprises transmitting a successful LTM cell switch report to a network node (e.g., a target node the access in an LTM cell switch) including the information related to a successful execution of an LTM cell switch from a serving cell to an LTM candidate cell. Details of this information are provided below.

[0069] In some embodiments or instances, a method may include one or more of the following steps by the UE: the UE transmits the successful LTM cell switch report to the network node in response to a request for successful LTM cell switch report from the network node; the request for successful LTM cell switch report is included in a UE Information Request message; prior to receiving the request for successful LTM cell switch report the UE transmits an indication of availability of a successful LTM cell switch report; the successful LTM cell switch report is included in a UE Information Response message; the UE considers the execution of the LTM cell switch to the LTM candidate cell as a successful LTM cell execution in response to i) an internal indication from a first protocol layer to a second protocol layer; and / or ii) an indication received from the network; and / or iii) a transmission from the UE. This is what would trigger the UE to perform actions related to the generation and transmission of successful LTM cell switch report; the UE generates the successful LTM cell switch report in response of one or more of the following: o determining that the execution of the LTM cell switch is successful; o determining that one or more of the conditions for the generation of the successful LMT cell switch report are fulfilled; generation of the successful LTM cell switch report imply the UE logging (or storing, e.g., in a UE variable) the information related to the successful execution of an LTM cell switch the UE logs the information related to the successful execution of an LTM cell switch when it has been configured with a reporting configuration for successful LTM cell switch report; the UE determines the content of the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report; the UE generates the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report. the reporting configuration for successful LTM cell switch report comprises one or more of the conditions for the generation of the successful LMT cell switch report.

[0070] The information related to the successful execution of an LTM cell switch comprises information received or derived as part of the LTM cell switch execution.

[0071] In various embodiments or instances, the information related to the successful execution of an LTM cell switch from the serving cell to the LTM candidate cell, received or derived as part of the LTM cell switch execution, may comprise one or more of: a) one or more fields the UE received in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; b) information associated to one or more serving cell(s), e.g., source SpCell, from which the UE received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; c) further information about the target candidate cell indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; d) further information about other LTM candidate cell(s), i.e., not the one indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; e) information related to the performance of the LTM cell switch associated to the successful LTM cell switch report; f) information related to cause for which the successful LTM cell switch report is being logged

[0072] Correspondingly, embodiments described herein include a UE for operating in a wireless network, where the UE is adapted to determine that an LTM cell switch triggered by an LTM cell switch command has been successfully executed and, upon determining that the execution of the LTM cell switch is successful, log information related to the successful execution of the LTM cell switch. The UE according to these embodiments is further adapted to transmit a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell. In some embodiments, the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

[0073] Approaches to the problems described above further include methods at a first network node (e.g., a target node accessed with the LTM cell switch), such as a method comprising the network node receiving, from a UE, a successful LTM cell switch report including information related to a successful execution of an LTM cell switch from a serving cell to an LTM candidate cell.

[0074] In various embodiments or instances, such a method may include one or more of the following steps by the first network node (which receives the successful LTM cell switch report): forwarding the successful LTM cell switch report to a second network node (e.g., S-DU, S-gNB- DU) in which the LTM cell switch associated to the successful LTM cell switch report was triggered; receiving the successful LTM cell switch report from the UE in response to a request for successful LTM cell switch report transmitted the first network node; prior to transmitting the request for successful LTM cell switch report the first network node receives from the UE an indication of availability of a successful LTM cell switch report. prior the UE executing the successful LTM cell switch, transmitting to the UE a reporting configuration for successful LTM cell switch report, wherein the reporting configuration may comprise one or more of the conditions associated to the first network node for the generation of the successful LMT cell switch report.

[0075] Also disclosed herein are methods at a second network node (e.g., a source node in which the UE executes the LTM cell switch), such as a method comprising the network node transmitting to the UE a reporting configuration for successful LTM cell switch report, wherein the reporting configuration may comprise one or more of the conditions associated to the second network node for the generation of the successful LMT cell switch report. Embodiments or instances of such a method may include the step of receiving the successful LTM cell switch report from a first network node receiving the successful LTM cell switch report from the UE.

[0076] Solutions described herein may be used to enable the network to configure the UE to collect the measurement and information concerning a successful LTM cell switch procedure, and hence use such information in optimizing the mobility control parameters for the LTM cell switch operations as well as the L3 mobility procedures. The successful LTM cell switch reports described herein indicate to the network information related to an LTM cell switch which was successful (i.e., it did not end up in a failure), but it may have been sub-optimal (e.g., long interruption time). The transmission of such a report would enable the network to possibly optimize its further LTM cell switch decisions.

[0077] BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 shows a high-level view of an exemplary 5G network architecture.

[0079] Figure 2 shows an exemplary configuration of NR UP and CP protocol stacks. Figure 3 illustrates the signaling procedure for LTM.

[0080] Figure 4 shows ramifications of Self-Configuration / Self-Optimization functionality (from 3GPP TS

[0081] 36.300 figure 22.1-1).

[0082] Figure 5 shows an exemplary method (e.g., procedure) for a UE, according to various embodiments of the present disclosure.

[0083] Figure 6 shows an exemplary method (e.g., procedure) for a network node, according to various embodiments of the present disclosure.

[0084] Figure 7 shows another exemplary method (e.g., procedure) for a network node, according to various embodiments of the present disclosure.

[0085] Figure 8 shows a communication system according to various embodiments of the present disclosure.

[0086] Figure 9 shows a UE according to various embodiments of the present disclosure.

[0087] Figure 10 shows a network node according to various embodiments of the present disclosure.

[0088] Figure 11 shows a host computing system according to various embodiments of the present disclosure.

[0089] Figure 12 is a block diagram of a virtualization environment in which functions implemented by some embodiments of the present disclosure may be virtualized.

[0090] Figure 13 illustrates communication between a host computing system, a network node, and a UE via multiple connections, at least one of which is wireless, according to various embodiments of the present disclosure.

[0091] DETAILED DESCRIPTION

[0092] This disclosure uses the term "L1 / L2 based inter-cell mobility" as used in the Work Item Description in 3GPP, though it interchangeably also uses the terms L1 / L2 mobility, Ll-mobility, LI based mobility, Ll / L2-centric inter-cell mobility, L1 / L2 inter-cell mobility Ll / L2-Triggered Mobility, Lower-layer Triggered Mobility or simply LTM. The basic principle of LTM is that the UE receives a lower layer signaling from the network indicating to the UE a change (or switch or activation) of its serving cell (e.g., change of PCell, from a source to a target Peel I) in accordance with configuration information previously received by the UE, 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 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). An LTM candidate cell configuration may include parameters in the IE CellGroupConfig per candidate cell and / or an embedded RRC Reconfiguration per LTM candidate cell.

[0093] The term LTM cell switch procedure refers to the process of a UE switching (or changing) its cell from a source cell to a target cell (which may be called here an LTM candidate cell or a neighbour cell), using Ll / L2-triggered mobility (LTM). In the context of Ll / L2-triggered mobility (LTM), an LTM cell switch procedure may sometimes also be known as 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 invention, switching to the LTM candidate cell configuration comprises 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 Master Cell Group (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.

[0094] Where the term "change of cell" is used, the change of cell may comprise 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 Seel Is of the cell group (e.g., addition, modification and / or release of one or more Scells).

[0095] An LTM cell switch procedure may be triggered in the UE by reception of a LTM cell switch command, e.g., a MAC CE.

[0096] This document often refers to an LTM candidate cell, which is 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 called 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 network may take educated decision on which beam (e.g. 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). This disclosure also refers often to "at least one LTM candidate cell configuration" and may state that the UE has received at least one LTM candidate cell configuration. This is also sometimes 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 Ll / L2-Triggered Mobility. A LTM candidate cell configuration comprises 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 an 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. The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising 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). A LTM candidate cell configuration may in one example comprise one or more of: i) the PCell configuration and one or more SCell configuration(s) of a Master Cell Group (MCG); i) the PSCell configuration and one or more SCell configuration(s) of a secondary Cell Group (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 LTM candidate cell. This identifier is sometimes known as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0097] The terms "triggering" the LTM cell switch or "executing" the LTM cell switch are used interchangeably in this disclosure.

[0098] An example method performed by a wireless terminal (so-called a user equipment (UE)) comprises transmitting a successful LTM cell switch report to a network node (e.g., a target node the access in an LTM cell switch), the LTM cell switch report including information related to a successful execution of an LTM cell switch from a serving cell to an LTM candidate cell.

[0099] In some embodiments or instances, the UE transmits the successful LTM cell switch report to the network node in response to a request for successful LTM cell switch report from the network node. In one option, the request for successful LTM cell switch report is included in a UE Information Request message (UElnformationRequest), e.g., as a field and / or Information Element in the message. In some embodiments or instances, prior to receiving the request for successful LTM cell switch report, the UE transmits an indication of availability of a successful LTM cell switch report. In one option, that indication of availability is included in a message transmitted to the LTM candidate cell (e.g., the target cell for LTM cell switch) indicated in the LTM cell switch command, e.g., in an RRC Reconfiguration Complete message or in a MAC CE transmitted to the LTM Candidate cell in response to the reception of the LTM cell switch command.

[0100] In some embodiments or instances, the successful LTM cell switch report is included in a UE Information Response message.

[0101] In some embodiments or instances, the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM cell execution in response to i) an internal indication from a first protocol layer to a second protocol layer; and / or ii) an indication received from the network; and / or iii) a transmission from the UE. This is what would trigger the UE to perform actions related to the successful LTM cell switch report.

[0102] • The internal indication from a first protocol layer to a second protocol layer may be an indication from the Medium Access Control (MAC) layer (or Layer 2, L2, or lower layers) to the Radio Resource Control (RRC) layer (or layer 3, or L3, or higher layers or Access Stratum (AS). The indication may be indicated from MAC to RRC upon a successful completion of a MAC layer procedure for the LTM cell switch execution, such as the successful completion of one or more or: a contention free (CF) random access procedure, a contention based (CB) random access procedure, a 2-step random access (CB or CF), a 4-step random access procedure (CB or CF), a LTM cell switch not relying on random access (RACH-less), depending which procedure was used for LTM cell switch; or a successful completion for an LTM cell switch procedure.

[0103] • The internal indication from a first protocol layer to a second protocol layer may be an indication from the Radio Link Control (RLC) to the RRC layer. The indication may indicate from RLC to MAC upon a successful reception of a RLC ACK after sending an RRC message due to the LTM cell switch procedure (e.g., an RRCReconfigurationComplete message).

[0104] • The indication received from the network may be a random access message, e.g., a Random Access Response (RAR), or a Contention Resolution message (MAC Control Element - MAC CE), or a message B for 2-step Random Access procedure. This is applicable in case the UE is configured to perform a random access procedure for LTM cell switch and the random access procedure is successful. • In one option, the LTM cell switch procedure is considered successful when in response to the LTM cell switch command the UE transmits a random access preamble and receives a RAR in response to it e.g. in case the LTM cell switch execution triggers a Contention Free Radnom Access (CFRA) procedure.

[0105] • In one option, the LTM cell switch procedure is considered successful when in response to the LTM cell switch command the UE transmits a random access preamble, receives a RAR in response to it, transmits a msg3, and receives a Contention Resolution message e.g. in case the LTM cell switch execution triggers a Contention Based Random Access (CBRA) procedure.

[0106] • In one option, the LTM cell switch procedure is considered successful when in response to the LTM cell switch command the UE transmits a random access preamble, receives a RAR in response to it, transmits a msg3, and receives a Contention Resolution message e.g. in case the LTM cell switch execution triggers a Contention Based Random Access (CBRA) procedure.

[0107] • The indication received from the network may in some cases be a Downlink message, on the lower layers, that is not a Random Access message. This is applicable in case the UE is configured to perform LTM cell switch without a random access procedure (i.e., a RACH-less LTM cell switch). o In one option, the UE receives the LTM cell switch command (e.g., MAC CE) and transmits a Scheduling Request on Physical Uplink Control Channel (PUCCH) and receives a Physical Downlink Control Channel (PDCCH) addressing a UE's identifier assigned to be used in the LTM candidate cell indicated in the LTM cell switch command (e.g., UE's Cell-Radio Network Temporary Identifier (C-RNTI)). Upon the reception of that PDCCH the UE considers the LTM cell switch procedure successful. o In one option, the UE receives the LTM cell switch command (e.g., MAC CE) and transmits Uplink (UL) information on Physical Uplink Shared (PUSCH) and receives a PDCCH addressing a UE's identifier assigned to be used in the LTM candidate cell indicated in the LTM cell switch command (e.g., UE's C-RNTI). Upon the reception of that PDCCH the UE considers the LTM cell switch procedure successful. o In one option, the UE receives the LTM cell switch command (e.g., MAC CE) and receives a PDCCH addressing a UE's identifier assigned to be used in the LTM candidate cell indicated in the LTM cell switch command (e.g., UE's C-RNTI). Upon the reception of that PDCCH the UE considers the LTM cell switch procedure successful. o In one option, when the UE (e.g. UE's MAC entity) has a C-RNTI, Temporary C-RNTI, CS-RNTI, G-RNTI or G-CS-RNTI, the UE (e.g. UE's MAC entity), for each PDCCH occasion during which it monitors PDCCH and for each Serving Cell; AND when there is an ongoing RACH-less LTM cell switch; AND when the downlink assignment has been received on the PDCCH for the UE's MAC entity's C-RNTI after the first PUSCH transmission to the Serving Cell; AND when the downlink assignment is for a new transmission: the UE considers the LTM cell switch to be successfully completed (and the UE indicates it to upper layers).

[0108] In some embodiments or instances, the UE logs (or stores, e.g., in a UE variable) the information related to the successful execution of an LTM cell switch when the UE determines that the execution of the LTM cell switch is successful, e.g., according to at least one of the possibilities listed above when determining that an LTM cell switch is successful.

[0109] In some embodiments or instances, the UE logs the information related to the successful execution of an LTM cell switch when it has been configured with a reporting configuration for successful LTM cell switch report. Such a reporting configuration may include instructions (e.g., triggering thresholds / event) to log and store measurement and information concerning a successful LTM cell switch procedure under certain conditions or previous target cell identities for which an LTM cell switch procedure has been triggered.

[0110] In some embodiments or instances, the UE determines the content of the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report. Further details are provided below, in the description of steps 1-3 of several steps performed by a wireless terminal.

[0111] In some embodiments or instances, the UE generates the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report. Further details are provided below, in the description of steps 1-3 of several steps performed by a wireless terminal.

[0112] In some embodiments or instances, the information related to the successful execution of an LTM cell switch from the serving cell to the LTM candidate cell, received or derived as part of the LTM cell switch execution, comprises one or more of: a) one or more fields the UE received in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; b) information associated to one or more serving cell(s), e.g., source SpCell, from which the UE received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; c) Further information about the target candidate cell indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; d) Further information about other LTM candidate cell(s), i.e., not the one indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; e) information related to the performance of the LTM cell switch associated to the successful LTM cell switch report; f) information related to cause for which the successful LTM cell switch report is being logged g) Further information about previous target candidate cell for which an LTM cell switch procedure has been completed (and for which an LTM cell switch command was not necessarily received).

[0113] Further details of these various information elements are provided below.

[0114] Embodiments of the techniques described herein may include some or all of the following set of steps performed by the wireless terminal (so-called a UE), in further detail:

[0115] Step 1:

[0116] Receiving a configuration including instructions (e.g., triggering conditions such as thresholds / event for the logging of information associated to the successful LTM cell switch) to log and store measurement and information concerning a successful LTM cell switch procedure under certain conditions.

[0117] • The configuration comprises thresholds and events; the thresholds and events are set by the network upon which the UE determines logging the successful LTM report upon fulfilment of one or more of the configured thresholds or events. o In various embodiments or instances, the triggering conditions are one or more of the following:

[0118] ■ Radio Link monitoring supervision timers, e.g., T310 timer and / or T312 timer as in successful handover report. For example, the UE logs the successful LTM cell switch report if the value of the timer T310 or T312 is above a certain relative or absolute value. In another example, the UE logs the report if the ratio between the value of the T310 / T312 and the configured value of T310 / T312 is above / below a certain configured percentage.

[0119] ■ LTM execution supervision timer, e.g., T304 timer, as in successful handover report. For example, the UE logs the successful LTM cell switch report if the value of the timer T304 is above a certain relative or absolute value. In another example, the UE logs the report if the ratio between the value of the T304 and the configured value of T304 is above / below a certain configured percentage.

[0120] ■ A flag indicating the UE to log the successful LTM cell switch report if the UE falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch.

[0121] ■ A flag indicating the UE to log the successful LTM cell switch report if the user plane interruption time is above / below a certain threshold.

[0122] ■ A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH).

[0123] ■ A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication.

[0124] ■ A list of cells such that if the UE performed LTM cell switch toward one of the listed cells the UE logs successful LTM cell switch report.

[0125] ■ A list of beam indexes (associated to the LTM candidate cells) such that if the UE performed LTM cell switch toward one of the listed beams associated to one or more cell, the UE logs the successful LTM cell switch report.

[0126] ■ An indication indicating the UE is to log the successful LTM cell switch report if the UE performed BFR right after the successful execution of the LTM cell switch.

[0127] ■ An indication indicating that the UE is to log the successful LTM cell switch if the UE performed LTM toward a beam different from the beam indicated in the LTM cell switch command.

[0128] In some embodiments or instances, the UE receives the successful LTM cell switch report configuration from the gNB-DU, e.g., as part of a MAC CE. The gNB-DU in these embodiments or instances configures the successful LTM cell switch report configuration and sends it to the UE.

[0129] In some other embodiments or instances, the UE receives the successful LTM cell switch report configuration from the gNB-CU, e.g., as part of RRC Reconfiguration message. The gNB-CU in these embodiments or instances configures the successful LTM cell switch report configuration and sends to the UE. The RRC reconfiguration message may be the same message in which LTM is configured, e.g., including an LTM candidate cell configuration.

[0130] In some embodiments or instances, the LTM cell switch report configuration including the one or more conditions is provided by the source gNB (DU or CU) of the LTM cell switch. In another embodiment, the LTM cell switch report configuration including the one or more conditions is provided by the target gNB (DU or CU) of the LTM cell switch. For example, the conditions pertaining to the target gNB, such as the threshold on the T304 timer, may be provided by the target gNB.

[0131] Step 2:

[0132] Performing an LTM cell switch procedure upon receiving an LTM execution indication from the network node e.g., gNB-DU either via a DCI indication in PDCCH or via a MAC CE, and successfully connecting to the target cell.

[0133] Step 3:

[0134] Determining whether to store and log measurement and information concerning the successfully executed LTM cell switch procedure, based on the received configuration in Step 1.

[0135] Step 4:

[0136] Logging measurements and information concerning the successfully executed LTM cell switch procedure in a UE storage upon determining whether to store the reports as done in Step 3. The measurements may comprise one or more of any of the following:

[0137] • Source cell ID and the associated measurements o The measurements may include layer 1 measurements. In a non-limiting example, the measurements, e.g., CSI measurements, are logged up to the moment of the LTM execution. o The measurements may also include layer 3 measurements. In a non-limiting example, the measurements, e.g., RSRP, RSRQ, SINR, or RSSI, performed and collected at the cell level or at beam level are logged up to the moment of the LTM execution.

[0138] • Target cell ID and the associated measurements o The measurements may include layer 1 measurements. In a non-limiting example, the measurements, e.g., CSI measurements, are logged up to the moment of the LTM execution. o The measurements may also include layer 3 measurements. In a non-limiting example, the measurements, e.g., RSRP, RSRQ., SINR, or RSSI, performed and collected at the cell level or at beam level are logged up to the moment of the LTM execution. o An indication indicating the beam index (SS / PBCH block CSI-RS indexes) the UE accessed when executing the LTM cell Switch.

[0139] • Neighbor cells identities and measurements o The measurements may include layer 1 measurements. In a non-limiting example, the measurements, e.g., CSI measurements, are logged up to the moment of the LTM execution. o The measurements may also include layer 3 measurements. In a non-limiting example, the measurements, e.g., RSRP, RSRQ, SINR, or RSSI, performed and collected at the cell level or at beam level are logged up to the moment of the LTM execution.

[0140] • An indication indicating whether each neighbor cell was a candidate LTM cell or not.

[0141] • An indication indicating time elapsed since receiving the LTM cell switch configuration till the successfully executing the LTM cell switch.

[0142] • An indication indicating the time elapsed since execution of the last layer 3 based mobility procedure.

[0143] • An indication indicating one or more fulfilled thresholds which based on them the successful LTM cell switch report is logged by the UE.

[0144] • An indication indicating the UE identifier e.g., C-RNTI of the source PCell and / or the target PCell C-RNTI.

[0145] • An indication indicating whether the UE received the Timing Advance (TA) value to perform a RACH less LTM cell switch procedure.

[0146] • An indication whether the UE estimated the TA value by itself (via UE based TA measurements) to perform RACH less LTM cell switch procedure and, eventually, the TA value of the estimated TA.

[0147] • An indication indicating the TA value if acquired by the UE for the successful LTM cell switch procedure.

[0148] • An indication indicating whether the UE falls back to the RACH based LTM cell switch procedure.

[0149] • An indication indicating the beam selected (SS / PBCH block CSI-RS indexes) by the UE for performing the RACH based LTM cell switch procedure, if it performed a RACH-based LTM cell switch.

[0150] • An indication indicating whether the RA access information have been received within the LTM cell switch command or within the LTM candidate cell

[0151] • The RA information associated to the RA procedure performed as part of successful LTM cell switch operation.

[0152] • An indication indicating whether the UE has used a configured grant or a dynamic grant to do the first UL transmission during the LTM cell switch procedure. Location information associated to the location at which the UE successfully performed the LTM cell switch procedure. o In some embodiments, the UE may provide the location information based on the location information configuration configured by the source PCell. o In some embodiments, the UE may provide the location information based on the location information configuration configured by the target PCell.

[0153] Step 5:

[0154] Sending the stored successful LTM cell switch report to the network, either directly or upon a network request received after indicating the availability of the report to the network.

[0155] • In some embodiments or instances, the UE logs the time elapsed from logging the successful LTM cell switch report until sending the report to the network.

[0156] • In some embodiments or instances, the UE sends the successful LTM cell switch report to the gNB-DU, e.g., if the gNB-DU configured the successful LTM cell switch report configuration. The gNB-DU may request the successful LTM cell switch report via a MAC CE.

[0157] • In some embodiments or instances, the UE sends the successful LTM cell switch report to the gNB-CU, e.g., if the gNB-CU configured the successful LTM cell switch report configuration. The gNB-CU may request the successful LTM cell switch report via UE information request message.

[0158] The successful LTM cell switch configuration and report may be "piggybacked" on a successful handover report, in some embodiments or instances:

[0159] • In some embodiments or instances, the UE receives the successful LTM cell switch configuration as part of the existing successful handover report configuration so-called successHO-Config according to the 3GPP TS 38.331 version 17.5.0.

[0160] • In some embodiments or instances, the UE logs and report the successful LTM cell switch report as part of the existing successful handover report so-called successHO-Report according to the TS 38.331 version 17.5.0.

[0161] The successful LTM cell switch report may be deleted by the UE at any of several times, e.g.:

[0162] • upon the report being fetched by the network.

[0163] • upon performing a new LTM cell switch.

[0164] • upon logging a new successful LTM cell switch report.

[0165] • after a certain period of time (e.g., 48 hours), if not being reported / retrieved to / by the network. In some embodiments or instances, when the UE applies the LTM candidate configuration due to an LTM cell switch (e.g., reconfigurationWithSync was included in spCellConfig of an Master Cell Group - MCG or Secondary Cell Group - SCG) and when the UE receives an indication from lower layer that the LTM cell switch execution has been successfully completed, the UE stops a supervision timer (e.g., T304) which had been started when LTM cell switch was triggered, and performs one or more actions related to the successful LTM cell switch report. In one option, the UE determines the remaining time which was left for the expiry of the supervision timer (or the elapsed time) and includes that value of the remaining time (or the elapsed time) in the success LTM cell switch report, to be transmitted to the network. With this approach, the network can see how much time the UE needed to access the LTM candidate cell and / or how much time the LTM cell switch procedure took.

[0166] In some embodiments or instances, the information included by the UE in the successful LTM cell switch report, related to the successful execution of an LTM cell switch from the serving cell to the LTM candidate, received or derived as part of the LTM cell switch execution, comprises one or more of: a) one or more fields the UE received in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report, such as: o The LTM candidate identifier (ID) of the LTM cell switch;

[0167] ■ This may also be called a Target Configuration identifier and it may refer to the index of candidate target configuration to apply for LTM cell switch, corresponding to the LTM candidate identifier minus 1 [Itm-Candidateld minus 1] in the RRC configuration for LTM.

[0168] ■ The advantage of indicating the target candidate ID is that it enables the network node in which the LTM cell switch was triggered to identify the target cell which had been selected for that possibly sub-optimal LTM cell switch. o Information related to the Timing Advance Command

[0169] ■ In one option, the UE includes the same information which had been included in the LTM cell switch command;

[0170] ■ In one option, the UE includes information based on the Timing Advance Command received in the LTM cell switch command e.g. an indication indicating whether the TA was valid or not (e.g. for the Primary TA group - PTAG of the LTM target cell), an indication indicating that no valid timing adjustment was available, and / or an index value TA used by the UE to control the amount of timing adjustment that the MAC entity has to apply, and / or whether the UE has skipped the Random Access procedure for this LTM cell switch. ■ The TA command in the LTM cell switch command indicated to the UE at the time of the LTM cell switch whether the TA was valid for the LTM target cell (i.e. the SpCell corresponding to the target configuration indicated by Target Configuration ID field). If the value of this field was set to FFF, this field indicated that no valid timing adjustment was available (e.g. for the Primary TA group - PTAG of the LTM target cell). Otherwise, it indicated the index value TA used to control the amount of timing adjustment that the MAC entity has to apply and that the UE can skip the Random Access procedure for this LTM cell switch.

[0171] ■ The inclusion is useful since it indicates to the network node receiving the report under which conditions the LTM cell switch has occurred e.g. validity of TA, whether that was a RACH based or RACH-less, etc.

[0172] ■ In one option, the UE includes information on whether it was configured to do UE based TA measurement in order to estimate the TA value by itself. In this case, the UE may include additional information such case the ID assigned for the UE based TA measurement feature, and what is the TA value estimated for the LTM cell switch. Information related to an indication of the "target beam" indicated in the LTM cell switch command:

[0173] ■ The "indication of the target beam" may correspond to a beam indication, TCI state ID, or Reference Signal ID associated to the target beam (e.g. SSB ID). That beam is associated to the LTM candidate cell indicated the target cell in the LTM cell switch command.

[0174] ■ In one option, that information corresponds to a TCI ID, that indicates the TCI state to be activated for the LTM target cell (i.e. the SpCell of the target configuration indicated by the Target Configuration ID field). The TCI state which had been indicated is identified by TCI-Stateld as in the RRC configuration of the LTM candidate cell indicated in the LTM cell switch command. If the value of unifiedTCI-StateType in the SpCell of the target configuration indicated by Target Configuration ID field is joint, this field is for joint TCI state, otherwise, this field is for downlink TCI state.

[0175] ■ The benefit of indicating the beam in the successful LTM cell switch report to the network is that it enables the network to identify the target beam in which the UE access associated to the other performance information the UE reports e.g. delay to access the LTM candidate cell. ■ In one option, the information corresponds to the Uplink (UL) TCI state ID and indicates the uplink TCI state for the LTM target cell (i.e. the SpCell of the target configuration indicated by the Target Configuration ID field) which was activated a the time of the LTM cell switch. o In an embodiment the UE includes the target beam identifier if the UE immediately after a successful LTM cell switch procedure changed the target beam e.g., performed a BFR right after successful LTM cell switch.

[0176] With the above information, such as candidate cell identifier or the configured TA value or the target beam indicated in the LTM cell switch command, the network can figure out the actual configuration used for the sub-optimally executed LTM cell switch procedure, and based on the other information and measurements in the report, e.g., CSI measurements, the network can optimize the candidate cells or the beam to be configured for the next LTM cell switch operation. o Information related to the usage of Random Access

[0177] ■ In one option, the information indicates whether CFRA, or CBRA or 2-step RA, or 4-step RA was used during the LTM cell switch procedure associated to the successful LTM cell switch report.

[0178] ■ In one option, the information indicates the presence of contention-free

[0179] Random Access Resources fields in the LTM cell switch command associated to the LTM cell switch associated to the successful LTM cell switch report.

[0180] ■ In one option the information indicates the usage by the UE of one or more of these during the LTM cell switch: Random Access Preamble index field, S / U field, SS / PBCH index field, PRACH Mask index field, wherein these were used for the LTM cell switch associated to the successful LTM cell switch report.

[0181] ■ In one option, the information indicates a Random Access Preamble index, which indicates the Random Access Preamble index of the contention-free Random Access Resources indicated to the UE in the LTM cell switch command.

[0182] ■ In one option, the information indicates which UL carrier the UE has used to transmit the PRACH of the contention-free Random Access Resources e.g. whether it was Supplementary UL or Noraml Uplink.

[0183] ■ In one option, the information indicates an SS / PBCH index which indicates the SS / PBCH that UE has used to determine the RACH occasion for the PRACH transmission of the contention-free Random Access Resources. ■ In one option, the information indicates a PRACH Mask index which indicates the RACH occasion associated with the SS / PBCH indicated by "SS / PBCH index" for the PRACH transmission of the contention-free Random Access Resources, referring to the rach-ConfigCommon in the UL BWP configuration of firstActiveUplinkBWP-ld in the RRC configuration of the LTM candidate cell indicated as the target candidate for the LTM cell switch. o The network may store the context information including UE's configuration at the time the failure has occurred, but the network may not store state related information, such as information included in the LTM cell switch command provided to a given UE at a given point in time. Hence, the importance of the UE to include information in the successful LTM cell switch report and transmit to the network, even though that information actually came from the network. o In an embodiment, the UE logs the RA related information if at least one of the report configuration associated to the random access procedure is fulfilled, in a non-limiting example, when the UE is configured to log the successful LTM cell switch report if the UE falls back from RACH-less to RACH-based LTM cell swtich the UE logs the RA related information. o With the RA information such as RA type performed by the UE, the network can figure out the actual configuration and resources used for the random access procedure were optimal or not. With such information, the network can optimize the RA procedure for the next LTM cell switches properly. b) information associated to one or more serving cell(s), e.g., source SpCell, from which the UE received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report, such as: o An identifier associated to a serving cell (e.g SpCell) from which the UE receives the LTM cell switch associated to the successful LTM cell switch report e.g. a PCI, a cell identity, an LTM configuration identity (in case the serving cell was also a candidate for sub-sequent LTM). That would enable the network node receiving the report to identify the source cell at the moment of the LTM cell switch. o An indication of the activated TCI state of the serving cell when the UE has received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report. That would enable the network node receiving the report to identify the activated TCI state (and spatial direction and / or RS identifier associated) at the moment of the LTM cell switch. An indication of a beam (e.g. beam identifier), e.g., of the serving cell, when the UE has received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report. That would enable the network node receiving the report to identify the source beam (or the activated TCI state) at the moment of the LTM cell switch. One or more measurements of the serving cell, such as :

[0184] ■ Cell measurement(s) such as cell-based RSRP, RSRQ or SINR e.g. based on SSB and / or CSI-RS;

[0185] ■ Beam measurement(s) such as SSB based or and / or CSI-RS-based RSRP, RSRQ. or SINR per beam of the serving cell.

[0186] ■ Beam measurement(s) of the beam in which the UE has received the LTM cell switch command. That may give insights to the network what was the situation of the UE's source beam at the moment of the LTM cell switch.

[0187] ■ SSB and / or CSI-RS measurement(s) associated to the TCI state which was activated when the UE has received the LTM cell switch command. Being associated in this context means that ta given SSB (e.g. SSB index=X) or CSI-RS is / are configured as Quasi-Co-Location (QCL) source of the activated TCI state. That may give insights to the network what was the situation of the UE's source TCI state at the moment of the LTM cell switch.

[0188] ■ Other available beam measurement(s) of beams which are different from the beam in which the UE has received the LTM cell switch command. That may give insights to the network what was the situation of other beams in contrast to the UE's source beam at the moment of the LTM cell switch. A sub-optimal performance may have happened possibly due to the poor beam coverage from the source's perspective, which could indicate that the UE should have been in another source's beam before receiving the LTM cell switch command. Or, that the LTM cell switch should have not been triggered in case there were good beams from the serving cell.

[0189] ■ Other available SSB / CSI-RS measurement(s) associated to other TCI state(s) different from the TCI state activated when the UE has received the LTM cell switch command. That may give insights to the network what was the situation of other SSBs / CSI-RSs in contrast to the UE's source TCI state activated at the moment of the LTM cell switch. A sub-optimal performance may have happened possibly due to the poor coverage for the source's TCI state which was activated, which could indicate that the UE should have another source's TCI state activated instead before receiving the LTM cell switch command. Or, that the LTM cell switch should have not been triggered in case there were good TCI states which could have been activated in the serving cell.

[0190] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are lower layer measurements e.g. Ll-RSRP, Ll-SINR, , Ll-RSRQ, SS-RSRP, SS-RSRQ, SS-SINR, or differential Ll-RSRP, etc. In one sub-option, these are available lower layer measurements performed according to a LTM CSI reporting configuration and / or a LTM CSI resource configuration. In one suboption, these are available lower layer measurements performed according to a CSI reporting configuration (for intra-cell beam management) and / or a CSI resource configuration (for intra-cell beam management).

[0191] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are Layer 3 (L3) filtered beam measurements. In one sub-option, these are available L3 measurements performed according to a MeasConfig.

[0192] With the above information related to the measurements at the cell level and beam level, in particular if combined with the candidate cells and target beam (and non-target beams) and the configured TA value, the network can figure out the optimal configuration for the LTM cell switch procedure and optimize the candidate cells or the beam to be configured for the next LTM cell switch operation. c) Further information about the target candidate cell indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report, such as: o One or more measurements of the target candidate cell, such as:

[0193] ■ Cell measurement(s) such as cell-based RSRP, RSRQ or SINR e.g. based on SSB and / or CSI-RS;

[0194] ■ Beam measurement(s) such as SSB based or and / or CSI-RS-based RSRP, RSRQ. or SINR per beam of the target cell.

[0195] ■ Beam measurement(s) of the beam which the UE uses upon reception of the LTM cell switch command. In this context, "uses upon reception" means that the UE monitors DL control channel(s), e.g., PDCCH of the target candidate cell in that beam. That may give insights to the network regarding the situation of the UE's target beam at the moment of the LTM cell switch. ■ SSB and / or CSI-RS measurement(s) associated to the TCI state of the target candidate which is activated in response when the UE has received the LTM cell switch command. Being associated in this context means that a given SSB (e.g. SSB index=X) or CSI-RS is / are configured as Quasi-Co-Location (Q.CL) source of the activated TCI state. That may give insights to the network what was the situation of the UE's target candidate TCI state at the moment, or shortly before after the LTM cell switch.

[0196] ■ Other available beam measurement(s) of beams of the target candidate cell which are different from the beam in which the UE monitors DL control channel(s) in the target candidate cell in response to the LTM cell switch command. That may give insights to the network what was the situation of other beams of the target cell (which in principle could have been selected by the network and indicated in the LTM cell switch command) in contrast to the target beam at the moment of the LTM cell switch. A sub-optimal performance may have happened possibly due to the fact that the network has not indicated the optimal beam of the target cell to the UE in the LTM cell switch command.

[0197] ■ Other available SSB / CSI-RS measurement(s) associated to other TCI state(s) different from the TCI state activated of the LTM target candidate cell when the UE has received the LTM cell switch command. That may give insights to the network what was the situation of other SSBs / CSI-RSs of the target candidate cell in contrast to the TCI state of the target candidate cell indicated to be activated by the LTM cell switch command.

[0198] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are lower layer measurements e.g. Ll-RSRP, Ll-SINR, , Ll-RSRQ, SS-RSRP, SS-RSRQ, SS-SINR, or differential Ll-RSRP, etc. In one sub-option, these are available lower layer measurements performed according to a LTM CSI reporting configuration and / or a LTM CSI resource configuration.

[0199] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are Layer 3 (L3) filtered beam measurements.

[0200] With the above information related to the measurements at the cell level and beam level of the candidate cell in particular if combined with the candidate cells and target beam (and non-target beams) and the configured TA value, the network can figure out the optimal configuration for the LTM cell switch procedure and optimize the candidate cells or the beam to be configured for the next LTM cell switch operation. d) Further information about other LTM candidate cell(s), i.e., not the one indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report, such as: o The LTM candidate identifier (ID) of the other LTM candidate cell(s);

[0201] ■ This may refer to the ID associated to an LTM candidate cell as configured as part of the LTM configuration, e.g., Itm-Candidateld, in the RRC configuration for LTM.

[0202] ■ An advantage of indicating the LTM candidate ID is that it enables the network node in which the LTM cell switch was triggered to identify information about other LTM candidate cells which had not been selected for that possibly sub- optimal LTM cell switch. o One or more measurements of the other candidate cell(s), such as :

[0203] ■ Cell measurement(s) such as cell-based RSRP, RSRQ or SINR e.g. based on SSB and / or CSI-RS;

[0204] ■ Beam measurement(s) such as SSB based or and / or CSI-RS-based RSRP, RSRQ. or SINR per beam of the target cell.

[0205] ■ Beam measurement(s) of the beam which the UE uses upon reception of the LTM cell switch command. In this context, using, means that the UE monitors DL control channel(s) e.g. PDCCH of the target candidate cell in that beam. That may give insights to the network what was the situation of the UE's target beam at the moment of the LTM cell switch.

[0206] ■ SSB and / or CSI-RS measurement(s) associated to the TCI state of the target candidate which is activated in response when the UE has received the LTM cell switch command. Being associated in this context means that a given SSB (e.g. SSB index=X) or CSI-RS is / are configured as Quasi-Co-Location (QCL) source of the activated TCI state. That may give insights to the network what was the situation of the UE's target candidate TCI state at the moment, or shortly before after the LTM cell switch.

[0207] ■ Other available beam measurement(s) of beams of the target candidate cell which are different from the beam in which the UE monitors DL control channel(s) in the target candidate cell in response to the LTM cell switch command. That may give insights to the network what was the situation of other beams of the target cell (which in principle could have been selected by the network and indicated in the LTM cell switch command) in contrast to the target beam at the moment of the LTM cell switch. A sub-optimal performance may have happened possibly due to that the network has not indicated the optimal beam of the target cell to the UE in the LTM cell switch command.

[0208] ■ Other available SSB / CSI-RS measurement(s) associated to other TCI state(s) different from the TCI state activated of the LTM target candidate cell when the UE has received the LTM cell switch command. That may give insights to the network what was the situation of other SSBs / CSI-RSs of the target candidate cell in contrast to the TCI state of the target candidate cell indicated to be activated by the LTM cell switch command.

[0209] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are lower layer measurements e.g. Ll-RSRP, Ll-SINR, , Ll-RSRQ, SS-RSRP, SS-RSRQ, SS-SINR, or differential Ll-RSRP, etc. In one sub-option, these are available lower layer measurements performed according to a LTM CSI reporting configuration and / or a LTM CSI resource configuration.

[0210] ■ In one option, the beam measurement or SSB measurements, or CSI-RS measurements are Layer 3 (L3) filtered beam measurements. In one sub-option, these are available L3 measurements performed according to a MeasConfig. o In one option, the LTM candidates for which information is included are limited to the LTM candidate cells in the same frequency as the serving frequency of the UE's current SpCell, when the UE receives the LTM cell switch command.

[0211] ■ The "same frequency" in this context may correspond to the same SSB frequency, the same point A frequency (e.g., same reference for resource block #0), same subcarrier spacing. o In one option, the LTM candidate for which information is included are limited to the "best" LTM candidate cells in terms of a measurement quantity, e.g., RSRP.

[0212] ■ The "best" In this context would mean the strongest cells in terms of the measurement quantity, e.g., strongest RSRP.

[0213] With the above information related to the measurements at the cell level and beam level of the candidate cells not indicated in the cell switch command in particular if combined with the candidate cells and target beam (and non-target beams) and the configured TA value, the network can figure out the optimal configuration for the LTM cell switch procedure and optimize the candidate cells or the beam to be configured for the next LTM cell switch operation. e) Information related to the performance of the LTM cell switch associated to the successful LTM cell switch report, such as: interval between the LTM configuration phase and the LTM execution phase

[0214] ■ In one option, the information comprises the time interval between the reception of the LTM configuration for a given LTM candidate cell by the UE (TO) and the reception of the LTM cell switch command;

[0215] • In one option, TO is maintained separately for each of the LTM candidate cell included in the LTM configuration. Thus, if there is a modification in the LTM candidate configuration after receiving the first LTM candidate configuration then the UE would continue to use the time of reception of first LTM candidate configuration as TO for whose cells which are not modified or removed in the subsequent LTM candidate configuration. Further, the UE would start new timer for those cells that are newly added in the subsequent LTM configuration or those cells whose LTM configurations were modified in the subsequent LTM configuration. o This option provides more detailed information per LTM candidate cell which would aid the network to know which LTM candidate might be configured more recently and which other LTM candidate cell might be configured at a much earlier point in time.

[0216] • In one option, a single TO related timer is maintained for all the LTM candidate cells i.e., every time a new LTM configuration is received, the UE would reset the TO to the time of reception of the latest LTM configuration. o This option is simpler for the UE as this reduces the number of computations / processing and memory required for the UE.

[0217] ■ In one option, the information comprises the time elapsed between the initiation of the LTM cell switch execution for the target candidate cell and the reception of the last LTM configuration including the LTM candidate cell configuration of the target candidate cell indicated in the LTM cell switch command;

[0218] ■ In one option, the information comprises the time elapsed between the initiation of the LTM cell switch execution for the target candidate cell and the transmission of the latest lower layer measurement report (for LTM);

[0219] ■ One benefit in transmission this information is to enable the network to understand how long resource were being reserved for a given procedure ■ In one option, the information comprises the time elapsed between the reception of the LTM cell switch command and the transmission of the RRC reconfiguration complete message to the target candidate cell indicated in the LTM cell switch command.

[0220] ■ In one option, the information comprised the time elapsed between the reception the reception of the LTM cell switch command and the transmission of the first UL transmission to the target candidate cell indicated in the LTM cell switch command after the LTM cell switch procedure has been considered completed. Information related to the "state" of a supervision timer (e.g. timer T304) upon LTM cell switch

[0221] ■ When the UE receives the LTM cell switch command the UE starts a supervision timer (e.g. timer T304). The timer is stopped when the UE is indicated that the procedure is successful (e.g. indication from lower layers to RRC).

[0222] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the time elapsed for timer T304 from the instant the UE started until the instant in which the timer was stopped. That indicates to the network how much time it took to perform the LTM cell switch.

[0223] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the value of the timer T304 when it was stopped. That indicates to the network how much time it took to perform the LTM cell switch.

[0224] ■ In one option, the UE includes in the successful LTM cell switch report the ratio between the value of the elapsed time of the supervision timer (e.g. T304) and the configured value of the supervision timer (configured value for T304) included in the LTM candidate cell configuration applied in response to the LTM cell switch. Information related to how prepared the UE was for applying the LTM candidate cell configuration.

[0225] ■ When the UE receives the LTM cell switch command the needs to apply the stored LTM candidate cell configuration indicated in the LTM cell switch command. That may include the time it takes to generate the complete LTM candidate cell configuration e.g. based on the reference configuration and / or the UE's current configuration. ■ In one option, the UE includes in the successful LTM cell switch report the time elapsed from the instant the UE receives the LTM cell switch command until the instant in which the supervision timer is started, which is an indication that the RRC configuration of the LTM candidate cell has been processed.

[0226] ■ In one option, the UE includes in the successful LTM cell switch report the time elapsed from the instant the UE receives the LTM candidate cell configuration until the time on when the LTM candidate cell configuration has been applied by the UE.

[0227] ■ In one option, the UE includes the in the successful LTM cell switch report the time elapsed from the instant the UE receives the LTM candidate cell configuration until the time on when the UE has performed the ASN.l decoding and validity check on this LTM candidate cell configuration. Information related to the "state" of a Radio Link Failure (RLF) timer (e.g. timer T310) upon LTM cell switch

[0228] ■ When the UE receives the LTM cell switch command the UE may have an RLF timer running e.g. timer T310. That could be because while the UE was in the source cell, and before receiving the LTM cell switch command, the link quality of the serving cell (E.g. SpCell) degrades and the UE counts a number of out of sync indications from lower layers to higher layers above a counter e.g. N310 so the RLF timer is started. In other words, the UE may have been in a risky situation when it receives the LTM cell switch command and it may be useful for the network to be aware that LTM cell switch occurred in such a situation, indicating that perhaps it should have been triggered earlier.

[0229] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the time elapsed for the RLF timer (e.g. T310) from the instant the UE started the RLF timer until the instant in which the RLF timer was stopped (e.g. upon an indication from lower layer that the LTM cell switch execution has been successfully completed). That indicates to the network how much time the UE was in trouble before the UE successfully completed the LTM cell switch procedure.

[0230] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the value of the timer T310 when it was stopped. That indicates to the network how much time the UE was in trouble before the UE successfully completed the LTM cell switch procedure. ■ In one option, the UE includes in the successful LTM cell switch report the ratio between the value of the elapsed time of the RLF timer (e.g. T310) and the configured value of the RLF for the serving cell. That indicates to the network how much time the UE was in trouble before the UE successfully completed the LTM cell switch procedure. Information related to a counter associated to RLF timer (e.g. N310) upon LTM cell switch

[0231] ■ When the UE receives the LTM cell switch command the UE may started the counter for a number of failure indications e.g. Out of Sync (OOS) indication from lower layers. While the UE was in the source cell, and before receiving the LTM cell switch command, the link quality of the serving cell (E.g. SpCell) could be degraded and the UE counts a number of OOS indications from lower layers to higher layers, and, when that is not above the value set for N310 the situation is risky but the RLF timer has not started. In other words, the UE may have been in a risky situation when it receives the LTM cell switch command and it may be useful for the network to be aware that LTM cell switch occurred in such a situation, indicating that perhaps it should have been triggered earlier, otherwise the RLF timer (e.g., timer T310) would have started.

[0232] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the current number of OOS indications until the instant in which the LTM cell switch execution has been successfully completed. That indicates to the network how much time the UE was in trouble before the UE successfully completed the LTM cell switch procedure. Information related to a counter associated to Beam failure (e.g. Beam Failure Indication(s)) upon LTM cell switch

[0233] ■ When the UE receives the LTM cell switch command the UE may have started the counter for a number of BFI(S), for beam failure detection (BFD). A Beam Failure Recovery would have been triggered in case the number of BFI(s) exceeds a configured threshold. While the UE was in the source cell, and before receiving the LTM cell switch command, the link quality of the beam and / or Q.CL source of an activated TCI state of the serving cell (E.g. SpCell) could be degraded and the UE counts a number of BFI(s) from lower layers, and, when that is not above the value set for the BFI threshold the situation is risky in terms of BFR, but that has not (yet) been triggered. In other words, the UE may have been in a risky situation for BFD when it receives the LTM cell switch command and it may be useful for the network to be aware that LTM cell switch occurred in such a situation, indicating that perhaps it should have been triggered earlier, otherwise the BFR could have been triggered.

[0234] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the current number of BFI(s) until the instant in which the LTM cell switch execution has been successfully completed. That indicates to the network whether and to which extent the UE was in trouble before the UE successfully completed the LTM cell switch procedure.

[0235] ■ Thus, in one option, the UE includes in the successful LTM cell switch report the ratio between the value of the BFI at the time of the LTM cell switch and the configured value of the BFI threshold for the serving cell.

[0236] In a non-limiting example embodiment, the information related to the performance of the LTM cell switch procedure will be logged by the UE only if at least one of the configurations associated to the performance of the LTM cell switch procedure is fulfilled during the successful execution of the LTM cell switch procedure. For example, the UE may log one or more information related to the performance of the LTM cell switch procedure is the triggering condition for successful LTM cell switch report is T304 related threshold or T310 or T312 related threshold.

[0237] With such information, the network can optimize the radio link failure parameters, such as T310 or T312, or decide to trigger the next LTM cell switch procedure earlier to avoid that such timers start running. f) Information related to cause for which the successful LTM cell switch report is being logged o That may be related to the configuration for the report o In one option, the reporting configuration for successful LTM cell switch report may indicate to the UE that the report is to be logged when the ratio between the value of the elapsed time of the RLF timer (e.g. T310) and the configured value of the RLF for the serving cell is above a configured threshold, indicated in the reporting configuration for successful LTM cell switch report. In that case, the UE may include in the report a case value associated to the RLF timer e.g. t310-cause, or rlf-timer-cause or set a flag to 'true'. o In one option, the reporting configuration for successful LTM cell switch report may indicate to the UE that the report is to be logged when the ratio between the value of the elapsed time of the supervision timer (e.g. T304) and the configured value of the RLF for the serving cell is above a configured threshold, indicated in the reporting configuration for successful LTM cell switch report. In that case, the UE may include in the report a case value associated to the supervision timer e.g. t304-cause, or sup-timer- cause, or set a flag to 'true'. Similar reasoning may be applicable for the number of or ratio of BFI(s), etc. In one option, if the measurement quantity associated to a beam (e.g., SSB) of the source cell of the LTM switch procedure changes by more than a threshold, then the UE would include an indication in the successful LTM cell switch report that indicates that the fluctuations in the measurement quantity associated to the source cell is above the threshold.

[0238] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the source cell's measurement quantities to the time of receiving the LTM cell switch command.

[0239] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the source cell's measurement quantities to the time of executing the LTM cell switch procedure.

[0240] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the source cell's measurement quantities to the time of completing the LTM cell switch procedure.

[0241] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of receiving the LTM cell switch command.

[0242] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of executing the LTM cell switch procedure.

[0243] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of completing the LTM cell switch procedure. In one option, if the measurement quantity associated to a beam (e.g., SSB) of the target LTM cell of the LTM switch procedure changes by more than a threshold, then the UE would include an indication in the successful LTM cell switch report that indicates that the fluctuations in the measurement quantity associated to the target LTM cell is above the threshold.

[0244] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the target cell's measurement quantities to the time of receiving the LTM cell switch command.

[0245] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the target cell's measurement quantities to the time of executing the LTM cell switch procedure.

[0246] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the target cell's measurement quantities to the time of completing the LTM cell switch procedure.

[0247] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of receiving the LTM cell switch command.

[0248] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of executing the LTM cell switch procedure.

[0249] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of completing the LTM cell switch procedure. In one option, if the measurement quantity associated to the beam (e.g., SSB) of the target LTM cell of the LTM switch procedure that is indicated as part of the LTM cell switch command changes by more than a threshold, then the UE would include an indication in the successful LTM cell switch report that indicates that the fluctuations in the measurement quantity associated to the beam of target LTM cell that is indicated in the LTM cell switch command is above the threshold.

[0250] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the beam of the target cell that is included in the LTM cell switch command to the time of receiving the LTM cell switch command. ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the beam of the target cell that is included in the LTM cell switch command to the time of executing the LTM cell switch procedure.

[0251] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the beam of the target cell that is included in the LTM cell switch command to the time of completing the LTM cell switch procedure.

[0252] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of receiving the LTM cell switch command.

[0253] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of executing the LTM cell switch procedure.

[0254] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of completing the LTM cell switch procedure. In one option, if the measurement quantity associated to a beam (e.g., SSB) of a candidate LTM cell associated to the LTM configuration changes by more than a threshold, then the UE would include an indication in the successful LTM cell switch report that indicates that the fluctuations in the measurement quantity associated to the candidate LTM cell is above the threshold.

[0255] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the candidate LTM cell's measurement quantities to the time of receiving the LTM cell switch command.

[0256] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the candidate cell's measurement quantities to the time of executing the LTM cell switch procedure.

[0257] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) including the candidate LTM cell's measurement quantities to the time of completing the LTM cell switch procedure. ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of receiving the LTM cell switch command.

[0258] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of executing the LTM cell switch procedure.

[0259] ■ In one option, the change in the measurement quantity is measured between the time instances of the transmission of the last measurement report (e.g., CSI report) to the time of completing the LTM cell switch procedure.

[0260] Including the cause of which the successful LTM cell switch is logged enables the network to better pinpoint the root cause issues for the sub-optimal performance of the executed LTM cell switch procedure.

[0261] Methods described above include, but are not limited to, the following examples.

[0262] 1. A method performed by a user equipment (UE), the method comprising: transmitting a successful LTM cell switch report to a network node, wherein the successful LTM cell switch report includes information related to a successful execution of an LTM cell switch from a serving cell to an LTM candidate cell, wherein the information related to the successful execution of an LTM cell switch from the serving cell to the LTM candidate cell, received or derived as part of the LTM cell switch execution, comprises one or more of: a) one or more fields the UE received in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; b) information associated to one or more serving cell(s), e.g., source SpCell, from which the UE received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; c) further information about the target candidate cell indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; d) further information about other LTM candidate cell(s), i.e., not the one indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; e) information related to the performance of the LTM cell switch associated to the successful LTM cell switch report; f) information related to cause for which the successful LTM cell switch report is being logged

[0263] 2. A method according to 1, further comprising transmitting the successful LTM cell switch report to the network node in response to a request for successful LTM cell switch report from the network node.

[0264] 3. A method according to 1, 2 wherein the request for successful LTM cell switch report is included in a UE Information Request message.

[0265] 4. A method according to 1, 2, 3 wherein prior to receiving the request for successful LTM cell switch report, transmitting an indication of availability of the successful LTM cell switch report.

[0266] 5. A method according to 1, 2, 3, 4, wherein the successful LTM cell switch report is included in a UE Information Response message.

[0267] 6. A method according to 1, 2, 3, 4, 5, wherein determining the execution of the LTM cell switch to the LTM candidate cell as a successful LTM cell execution in response to i) an internal indication from a first protocol layer to a second protocol layer; and / or ii) an indication received from the network; and / or iii) a transmission from the UE. This is what would trigger the UE to perform actions related to the successful LTM cell switch report.

[0268] 7. A method according to 1, 2, 3, 4, 5, 6, further comprising generating the successful LTM cell switch report when the UE determines that the execution of the LTM cell switch is successful.

[0269] 8. A method according to 1, 2, 3, 4, 5, 6, 7, further comprising generating the successful LTM cell switch report when the UE determines that one or more conditions for the generation of the successful LTM cell switch report are fullfilled.

[0270] 9. A method according to 7, 8, wherein generating the successful LTM cell switch report comprises logging (or storing e.g. in a UE variable) the information related to the successful execution of an LTM cell switch

[0271] 10. A method according to 1-9, further comprising logging the information related to the successful execution of an LTM cell switch when the UE has been configured with a reporting configuration for successful LTM cell switch report. 11. A method according to 10, wherein the reporting configuration for successful LTM cell switch report comprises one or more conditions for the logging of the information related to the successful execution, wherein one or more conditions can include any of: o LTM execution supervision timer e.g., T304 timer, as in successful handover report, i.e., the UE logs the successful LTM cell switch report if the value of the timer T304 is above a certain relative or absolute value. o A flag indicating the UE to log the successful LTM cell switch report if the UE falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch. o A flag indicating the UE to log the successful LTM cell switch report if the user plane interruption time is above / below a certain threshold. o A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH). o A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication. o A list of cells such that if the UE performed LTM cell switch toward one of the listed cells the UE logs successful LTM cell switch report. o A list of beam indexes (associated to the LTM candidate cells) such that if the UE performed LTM cell switch toward one of the listed beam associated to one or more cell, the UE logs the successful LTM cell switch report.

[0272] 12. A method according to 1-11, further comprising determining the content of the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report.

[0273] 13. A method according to 1-12, further comprising generating the successful LTM cell switch report based on the reporting configuration for successful LTM cell switch report.

[0274] 14. A method according to 1-13, wherein the information related to the successful execution of an LTM cell switch comprises: information received or derived as part of the LTM cell switch execution.

[0275] 15. A method performed by a first network node (e.g., a target node the access in an LTM cell switch), the method comprising receiving from a UE a successful LTM cell switch report including information related to a successful execution of an LTM cell switch from a serving cell to an LTM candidate cell, wherein the information and measurements can be one or more of a) one or more fields the UE received in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; b) information associated to one or more serving cell(s), e.g., source SpCell, from which the UE received the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; c) Further information about the target candidate cell indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; d) Further information about other LTM candidate cell(s), i.e., not the one indicated in the LTM cell switch command, associated to the LTM cell switch associated to the successful LTM cell switch report; e) information related to the performance of the LTM cell switch associated to the successful LTM cell switch report; f) information related to cause for which the successful LTM cell switch report is being logged

[0276] 16. A method according to 15, wherein the successful LTM cell switch report includes information related to a second network node (e.g. S-DU, S-gNB-DU) in which the LTM cell switch associated to the successful LTM cell switch report was triggered.

[0277] 17. A method according to 15 or 16, the method further comprising the network node (e.g. Central Unit, gNB-CU) forwarding the successful LTM cell switch report to a second network node (e.g. S-DU, S-gNB-DU, another CU-gNB) in which the LTM cell switch associated to the successful LTM cell switch report was triggered.

[0278] 18. A method according to 15-17, further comprising receiving the successful LTM cell switch report from the UE in response to a request for successful LTM cell switch report transmitted the first network node.

[0279] 19. A method according to 15-18, wherein prior to transmitting the request for successful LTM cell switch report the first network node receives from the UE an indication of availability of a successful LTM cell switch report.

[0280] 20. A method according to 15-19, wherein prior the UE executing the successful LTM cell switch, transmitting to the UE a reporting configuration for successful LTM cell switch report, wherein the reporting configuration may comprise one or more of the conditions to determine whether to log the successful LMT cell switch such as: a) LTM execution supervision timer, e.g., T304 timer, as in successful handover report, i.e., the UE logs the successful LTM cell switch report if the value of the timer T304 is above a certain relative or absolute value. b) A flag indicating the UE to log the successful LTM cell switch report if the UE falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch. c) A flag indicating the UE to log the successful LTM cell switch report if the user plane interruption time is above / below a certain threshold. d) A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH). e) A flag indicating the UE to log the successful LTM cell switch report if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication. f) A list of cells such that if the UE performed LTM cell switch toward one of the listed cells the UE logs successful LTM cell switch report. g) A list of beam indexes (associated to the LTM candidate cells) such that if the UE performed LTM cell switch toward one of the listed beam associated to one or more cell, the UE logs the successful LTM cell switch report.

[0281] 21. A method performed by a second network node (e.g., a source node in which the UE executes the LTM cell switch), the method comprising the network node transmitting to the UE a reporting configuration for successful LTM cell switch report,

[0282] 22. A method according to Cl, wherein the reporting configuration comprises one or more of the conditions associated to the second network node for the generation of the successful LMT cell switch report.

[0283] 23. A method performed by a second network node, comprising receiving the successful LTM cell switch report from a first network node receiving the successful LTM cell switch report from the UE.

[0284] In view of the detailed examples given above, it should be understood that Figure 5 is a process flow illustrating an example method carried out by a UE or other wireless terminal operating in a wireless network. The illustrated method is intended to be a generalization of the UE-related techniques described above - hence, where terminology used to describe the method of Figure 5 differs in some respects from similar or related terminology used above, the former should be understood to at least encompass the latter, unless the context clearly indicates otherwise. As shown at block 510, the method includes the step of determining that a Layer 1 / Layer 2 - triggered mobility (LTM) cell switch triggered by an LTM cell switch command has been successfully executed. In some embodiments or instances, the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM cell execution in response to i) an internal indication from a first protocol layer to a second protocol layer; and / or ii) an indication received from the network; and / or iii) a transmission from the UE. This is what would trigger the UE to perform actions related to the successful LTM cell switch report. The indication received from the network may be a message other than a Random Access message. Thus, in some embodiments, the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

[0285] As shown at block 520, the method further includes the step of transmitting a report of the successful LTM cell switch. This report may comprise any one or more of any of:

[0286] • one or more fields received in the LTM cell switch command;

[0287] • information associated to one or more serving cell(s) from which the UE received the LTM cell switch command;

[0288] • information about a target candidate cell indicated in the LTM cell switch command;

[0289] • information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command;

[0290] • information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report;

[0291] • information indicating a cause of the successful LTM cell switch report being logged.

[0292] As noted above, in some embodiments of instances, determining that the LTM cell switch has been successfully executed may be based on at least one of: an indication sent from a first protocol layer in the UE or other wireless terminal to another protocol layer; an indication received from the wireless network; and a transmission by the UE or other wireless terminal to the wireless network. In some embodiments or instances, the UE receives the LTM cell switch command and a PDCCH addressing an identifier of the UE assigned to be used in the LTM candidate cell indicated in the LTM cell switch command, and the UE considers the LTM cell switch procedure successful upon reception of the PDCCH.

[0293] In some embodiments or instances, the method comprises: logging information for the report upon determining that the LTM cell switch has been successfully executed, as shown at block 512 in Figure 5; and subsequently transmitting the report. In some embodiments or instances, the report comprises one or more information elements indicated in a reporting configuration previously received by the UE or other wireless terminal. In some of these embodiments or instances, the reporting configuration comprises one or more conditions for logging one or more respective information elements related to the successful LTM cell switch, the one or more conditions comprising any one or more of any of:

[0294] • a value or threshold for an LTM execution supervision timer;

[0295] • a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch;

[0296] • a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0297] • A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH);

[0298] • a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication;

[0299] • a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and

[0300] • a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0301] In some embodiments or instances, the transmitting is performed in response to receiving a request for the report. This is shown at block 516 in Figure 5. In some embodiments or instances, the method comprises transmitting an indication that the report is available, prior to receiving said request for the report. This is shown at block 513 in Figure 5.

[0302] Figure 6 and Figure 7 are each process diagrams illustrating respective methods performed in a network node operating in a wireless network, such as a gNB. Again, the illustrated methods are intended to be generalizations of the gNB techniques described above - hence, where terminology used to describe the method of Figure 6 or 7 differs in some respects from similar or related terminology used above, the former should be understood to at least encompass the latter, unless the context clearly indicates otherwise.

[0303] As shown at block 610, the first method comprises receiving, from a user equipment (UE) or other wireless terminal, a report of a successful LTM cell switch by the UE or other wireless terminal. The report may comprise any one or more of any of: • one or more fields received in the LTM cell switch command;

[0304] • information associated to one or more serving cell(s) from which the UE received the LTM cell switch command;

[0305] • information about a target candidate cell indicated in the LTM cell switch command;

[0306] • information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command;

[0307] • information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report;

[0308] • information indicating a cause of the successful LTM cell switch report being logged.

[0309] In some embodiments or instances, the network node operates the cell to which the LTM cell switch was successfully made. n some embodiments or instances, the method further comprises forwarding the report to a second network node. This is shown at block 620 in Figure 6.

[0310] In some embodiments or instances, the method comprises receiving the report in response to a request for the report sent to the UE or other wireless terminal. In some embodiments or instances, the method comprises receiving, from the UE or other wireless terminal, an indication that the report is available and sending the request for the report in response to said indication. These steps are shown at block 604 and 606 of Figure 6.

[0311] In some embodiments or instances, the method comprises sending, to a UE or other wireless terminal, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch, the one or more conditions comprising any one or more of any of:

[0312] • a value or threshold for an LTM execution supervision timer;

[0313] • a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch;

[0314] • a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0315] • A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH);

[0316] • a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; • a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and

[0317] • a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0318] Figure 7 illustrates another example method, as carried out by another network node operating in a wireless network. This network node might be the gNB serving the UE prior to an LTM cell switch, for example. As shown at block 710, this method comprises the step of sending, to a UE or other wireless terminal served by the network node, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch. The one or more conditions may comprise any one or more of any of:

[0319] • a value or threshold for an LTM execution supervision timer;

[0320] • a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch;

[0321] • a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0322] • A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH);

[0323] • a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication;

[0324] • a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and

[0325] • a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0326] In some embodiments or instances, the method may further comprise receiving, from a second network node, a report of a successful LTM cell switch by the UE or other wireless terminal. This is shown at block 720. The report may comprise any one or more of any of the following, in various embodiments or instances:

[0327] • one or more fields received in an LTM cell switch command triggering the successful LTM cell switch; • information associated to one or more serving cell(s) from which the UE received the LTM cell switch command;

[0328] • information about a target candidate cell indicated in the LTM cell switch command;

[0329] • information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command;

[0330] • information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report;

[0331] • information indicating a cause of the successful LTM cell switch report being logged.

[0332] Although various embodiments are described above in terms of methods, techniques, and / or procedures, the person of ordinary skill will readily comprehend that such methods, techniques, and / or procedures can be embodied by various combinations of hardware and software in various systems, communication devices, computing devices, control devices, apparatuses, non-transitory computer-readable media, computer program products, etc.

[0333] Figure 8 shows an example of a communication system 800 in accordance with some embodiments. In this example, communication system 800 includes telecommunication network 802 that includes access network 804 (e.g., RAN) and a core network 806, which includes one or more core network nodes 808. Access network 804 includes one or more access network nodes, such as network nodes 810a-b (one or more of which may be generally referred to as network nodes 810), or any other similar 3GPP access node or non-3GPP access point. Network nodes 810 facilitate direct or indirect connection of UEs, such as by connecting UEs 812a-d (one or more of which may be generally referred to as UEs 812) to core network 806 over one or more wireless connections.

[0334] 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, communication system 800 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. Communication system 800 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0335] UEs 812 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with network nodes 810 and other communication devices. Similarly, network nodes 810 are arranged, capable, configured, and / or operable to communicate directly or indirectly with UEs 812 and / or with other network nodes or equipment in telecommunication network 802 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in telecommunication network 802.

[0336] In the depicted example, core network 806 connects network nodes 810 to one or more hosts, such as host 816. 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. Core network 806 includes one or more core network nodes (e.g., 808) 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 core network node 808. 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).

[0337] Host 816 may be under the ownership or control of a service provider other than an operator or provider of access network 804 and / or telecommunication network 802, and may be operated by the service provider or on behalf of the service provider. Host 816 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.

[0338] As a whole, communication system 800 of Figure 8 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.

[0339] In some examples, telecommunication network 802 is a cellular network that implements 3GPP standardized features. Accordingly, telecommunication network 802 may support network slicing to provide different logical networks to different devices that are connected to telecommunication network 802. For example, telecommunication network 802 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.

[0340] In some examples, UEs 812 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to access network 804 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from access network 804. 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).

[0341] In the example, hub 814 communicates with access network 804 to facilitate indirect communication between one or more UEs (e.g., UE 812c and / or 812d) and network nodes (e.g., network node 810b). In some examples, hub 814 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, hub 814 may be a broadband router enabling access to core network 806 for the UEs. As another example, hub 814 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 810, or by executable code, script, process, or other instructions in hub 814. As another example, hub 814 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, hub 814 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, hub 814 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which hub 814 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, hub 814 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices. Hub 814 may have a constant / persistent or intermittent connection to network node 810b. Hub 814 may also allow for a different communication scheme and / or schedule between hub 814 and UEs (e.g., UE 812c and / or 812d), and between hub 814 and core network 806. In other examples, hub 814 is connected to core network 806 and / or one or more UEs via a wired connection. Moreover, hub 814 may be configured to connect to an M2M service provider over access network 804 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with network nodes 810 while still connected via hub 814 via a wired or wireless connection. In some embodiments, hub 814 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to network node 810b. In other embodiments, hub 814 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 810b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0342] Figure 9 shows a UE 900 in accordance with some embodiments. 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-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by 3GPP, including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0343] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP 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).

[0344] UE 900 includes processing circuitry 902 that is operatively coupled via bus 904 to input / output interface 906, power source 908, memory 910, communication interface 912, and possibly other components not explicitly shown. Certain UEs may utilize all or a subset of the components shown in Figure 9. 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.

[0345] Processing circuitry 902 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 memory 910. Processing circuitry 902 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 more stored 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, processing circuitry 902 may include multiple central processing units (CPUs).

[0346] In the example, input / output interface 906 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 UE 900. 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.

[0347] In some embodiments, power source 908 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. Power source 908 may further include power circuitry for delivering power from power source 908 itself, and / or an external power source, to the various parts of UE 900 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging power source 908. Power circuitry may perform any formatting, converting, or other modification to the power from power source 908 to make the power suitable for the respective components of UE 900 to which power is supplied. Memory 910 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 readonly 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, memory 910 includes one or more application programs 914, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 916. Memory 910 may store, for use by UE 900, any of a variety of various operating systems or combinations of operating systems.

[0348] Memory 910 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 (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as 'SIM card.' Memory 910 may allow UE 900 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 memory 910, which may be or comprise a device-readable storage medium.

[0349] Processing circuitry 902 may be configured to communicate with an access network or other network using communication interface 912. Communication interface 912 may comprise one or more communication subsystems and may include or be communicatively coupled to antenna 922. Communication interface 912 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 transmitter 918 and / or receiver 920 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, transmitter 918 and receiver 920 may be coupled to one or more antennas (e.g., 922) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0350] In the illustrated embodiment, communication functions of communication interface 912 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 be implemented 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), Q.UIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0351] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 912, 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 13 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., an alert is sent when moisture is detected), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0352] 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.

[0353] 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 in the 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 UE 900 shown in Figure 9.

[0354] 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-loT 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.

[0355] 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.

[0356] Figure 10 shows a network node 1000 in accordance with some embodiments. Examples of network nodes include, but are not limited to, access points (e.g., radio access points) and base stations (e.g., radio base stations, Node Bs, eNBs, and gNBs).

[0357] 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 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). 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).

[0358] Network node 1000 includes processing circuitry 1002, memory 1004, communication interface 1006, and power source 1008. Network node 1000 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 network node 1000 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 NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, network node 1000 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1004 for different RATs) and some components may be reused (e.g., a same antenna 1010 may be shared by different RATs). Network node 1000 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1000, 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 1000.

[0359] Processing circuitry 1002 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1000 components, such as memory 1004, to provide network node 1000 functionality.

[0360] In some embodiments, processing circuitry 1002 includes a system on a chip (SOC). In some embodiments, processing circuitry 1002 includes one or more of radio frequency (RF) transceiver circuitry 1012 and baseband processing circuitry 1014. In some embodiments, RF transceiver circuitry 1012 and baseband processing circuitry 1014 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 1012 and baseband processing circuitry 1014 may be on the same chip or set of chips, boards, or units.

[0361] Memory 1004 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 computer-executable memory devices that store information, data, and / or instructions that may be used by processing circuitry 1002. Memory 1004 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 (collectively denoted computer program product 1004a) capable of being executed by processing circuitry 1002 and utilized by network node 1000. Memory 1004 may be used to store any calculations made by processing circuitry 1002 and / or any data received via communication interface 1006. In some embodiments, processing circuitry 1002 and memory 1004 is integrated.

[0362] Communication interface 1006 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, communication interface 1006 comprises port(s) / terminal(s) 1016 to send and receive data, for example to and from a network over a wired connection. Communication interface 1006 also includes radio front-end circuitry 1018 that may be coupled to, or in certain embodiments a part of, antenna 1010. Radio front-end circuitry 1018 comprises filters 1020 and amplifiers 1022. Radio front-end circuitry 1018 may be connected to antenna 1010 and processing circuitry 1002. The radio front-end circuitry may be configured to condition signals communicated between antenna 1010 and processing circuitry 1002. Radio frontend circuitry 1018 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. Radio front-end circuitry 1018 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1020 and / or amplifiers 1022. The radio signal may then be transmitted via antenna 1010. Similarly, when receiving data, antenna 1010 may collect radio signals which are then converted into digital data by radio front-end circuitry 1018. The digital data may be passed to processing circuitry 1002. In other embodiments, the communication interface may comprise different components and / or different combinations of components. In certain alternative embodiments, network node 1000 does not include separate radio front-end circuitry 1018, instead, processing circuitry 1002 includes radio front-end circuitry and is connected to antenna 1010. Similarly, in some embodiments, all or some of RF transceiver circuitry 1012 is part of communication interface 1006. In still other embodiments, communication interface 1006 includes one or more ports or terminals 1016, radio front-end circuitry 1018, and RF transceiver circuitry 1012, as part of a radio unit (not shown), and communication interface 1006 communicates with the baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0363] Antenna 1010 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. Antenna 1010 may be coupled to radio front-end circuitry 1018 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, antenna 1010 is separate from network node 1000 and connectable to network node 1000 through an interface or port.

[0364] Antenna 1010, communication interface 1006, and / or processing circuitry 1002 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, antenna 1010, communication interface 1006, and / or processing circuitry 1002 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.

[0365] Power source 1008 provides power to the various components of network node 1000 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source 1008 may further comprise, or be coupled to, power management circuitry to supply the components of network node 1000 with power for performing the functionality described herein. For example, network node 1000 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 power source 1008. As a further example, power source 1008 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.

[0366] Embodiments of network node 1000 may include additional components beyond those shown in Figure 10 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, network node 1000 may include user interface equipment to allow input of information into network node 1000 and to allow output of information from network node 1000. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1000.

[0367] Figure 11 is a block diagram of a host 1100, which may be an embodiment of host 816 of Figure 8, in accordance with various aspects described herein. Host 1100 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. Host 1100 may provide one or more services to one or more UEs.

[0368] Host 1100 includes processing circuitry 1102 that is operatively coupled via a bus 1104 to an input / output interface 1106, a network interface 1108, a power source 1110, and a memory 1112. 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 9 and 10, such that the descriptions thereof are generally applicable to the corresponding components of host 1100.

[0369] Memory 1112 may include one or more computer programs including one or more host application programs 1114 and data 1116, which may include user data, e.g., data generated by a UE for host 1100 or data generated by host 1100 for a UE. Embodiments of host 1100 may utilize only a subset or all of the components shown. Host application programs 1114 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 audio codecs (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). Host application programs 1114 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, host 1100 may select and / or indicate a different host for over-the-top services for a UE. Host application programs 1114 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. Figure 12 is a block diagram illustrating a virtualization environment 1200 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 1200 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.

[0370] Applications 1202 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1100 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0371] Hardware 1204 includes processing circuitry, memory that stores software and / or instructions (collectively denoted computer program product 1204a) 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 1206 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1208a-b (one or more of which may be generally referred to as VMs 1208), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to VMs 1208.

[0372] VMs 1208 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1206. Different embodiments of the instance of a virtual appliance 1202 may be implemented on one or more of VMs 1208, and the implementations may differ. 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. In the context of NFV, each VM 1208 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 VMs 1208, and that part of hardware 1204 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 1208 on top of hardware 1204 and corresponds to application 1202.

[0373] Hardware 1204 may be implemented in a standalone network node with generic or specific components. Hardware 1204 may implement some functions via virtualization. Alternatively, hardware 1204 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 1210, which, among others, oversees lifecycle management of applications 1202. In some embodiments, hardware 1204 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 control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0374] Figure 13 shows a communication diagram of a host 1302 communicating via a network node 1304 with a UE 1306 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE 812a of Figure 8 and / or UE 900 of Figure 9), network node (such as network node 810a of Figure 8 and / or network node 1000 of Figure 10), and host (such as host 816 of Figure 8 and / or host 1100 of Figure 11) discussed in the preceding paragraphs will now be described with reference to Figure 13.

[0375] Like host 1100, embodiments of host 1302 include hardware, such as a communication interface, processing circuitry, and memory. Host 1302 also includes software, which is stored in or accessible by host 1302 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 UE 1306 connecting via an over-the- top (OTT) connection 1350 extending between UE 1306 and host 1302. In providing the service to the remote user, a host application may provide user data which is transmitted using OTT connection 1350. Network node 1304 includes hardware enabling it to communicate with host 1302 and UE 1306. Connection 1360 may be direct or pass through a core network (like core network 806 of Figure 8) 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.

[0376] UE 1306 includes hardware and software, which is stored in or accessible by UE 1306 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 1306 with the support of host 1302. In host 1302, an executing host application may communicate with the executing client application via OTT connection 1350 terminating at UE 1306 and host 1302. 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. OTT connection 1350 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 OTT connection 1350.

[0377] OTT connection 1350 may extend via a connection 1360 between host 1302 and network node 1304 and via wireless connection 1370 between network node 1304 and UE 1306 to provide the connection between host 1302 and UE 1306. Connection 1360 and wireless connection 1370, over which OTT connection 1350 may be provided, have been drawn abstractly to illustrate the communication between host 1302 and UE 1306 via network node 1304, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0378] As an example of transmitting data via OTT connection 1350, in step 1308, host 1302 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 UE 1306. In other embodiments, the user data is associated with a UE 1306 that shares data with host 1302 without explicit human interaction. In step 1310, host 1302 initiates a transmission carrying the user data towards UE 1306. Host 1302 may initiate the transmission responsive to a request transmitted by UE 1306. The request may be caused by human interaction with UE 1306 or by operation of the client application executing on UE 1306. The transmission may pass via network node 1304, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1312, network node 1304 transmits to UE 1306 the user data that was carried in the transmission that host 1302 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1314, UE 1306 receives the user data carried in the transmission, which may be performed by a client application executed on UE 1306 associated with the host application executed by host 1302. In some examples, UE 1306 executes a client application which provides user data to host 1302. The user data may be provided in reaction or response to the data received from host 1302. Accordingly, in step 1316, UE 1306 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 UE 1306. Regardless of the specific manner in which the user data was provided, UE 1306 initiates, in step 1318, transmission of the user data towards host 1302 via network node 1304. In step 1320, in accordance with the teachings of the embodiments described throughout this disclosure, network node 1304 receives user data from UE 1306 and initiates transmission of the received user data towards host 1302. In step 1322, host 1302 receives the user data carried in the transmission initiated by UE 1306.

[0379] One or more of the various embodiments improve the performance of OTT services provided to UE 1306 using OTT connection 1350, in which wireless connection 1370 forms the last segment. More precisely, embodiments can reduce and / or prevent undesired recovery actions by UEs. For example, due to the conditions for considering an LTM cell switch procedure successful (causing UE to stop a supervision timer), undesired recovery actions due to supervision timer expiration are prevented at the UE. This is especially an issue in the scenarios where LTM cell switch needs to be performed without a RA procedure (i.e., "RACH-less"). Preventing undesired recovery actions makes LTM RACH- less solutions more efficient, which reduces the delay to access an LTM candidate cell. Embodiments can facilitate predictable UE behavior in LTM execution failures and can reduce and / or eliminate ambiguity for UE actions in the event of LTM failures that are concurrent other failures such as radio link failure (RLF). By improving operation of UEs and RANs in this manner, embodiments increase the value of OTT services delivered to / from the UE via the RAN, to both end users and service providers.

[0380] In an example scenario, factory status information may be collected and analyzed by host 1302. As another example, host 1302 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, host 1302 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, host 1302 may store surveillance video uploaded by a UE. As another example, host 1302 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, host 1302 may be used for energy pricing, remote control of nontime 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. 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 OTT connection 1350 between host 1302 and UE 1306, 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 host 1302 and / or UE 1306. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which OTT connection 1350 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 OTT connection 1350 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of network node 1304. 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 host 1302. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or 'dummy' messages, using OTT connection 1350 while monitoring propagation times, errors, etc.

[0381] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

[0382] The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and / or electronic devices and can include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0383] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0384] As described herein, device and / or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and / or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

[0385] Furthermore, functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and / or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

[0386] In addition, certain terms used in the present disclosure, including the specification, drawings and embodiments thereof, can be used synonymously in certain instances, including, but not limited to, e.g., data and information. It should be understood that, while these words and / or other words that can be synonymous to one another, can be used synonymously herein, that there can be instances when such words can be intended to not be used synonymously. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly incorporated herein in its entirety. All publications referenced are incorporated herein by reference in their entireties. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0387] In addition, certain terms used in the present disclosure, including the specification and drawings, can be used synonymously in certain instances (e.g., "data" and "information"). It should be understood, that although these terms (and / or other terms that can be synonymous to one another) can be used synonymously herein, there can be instances when such words can be intended to not be used synonymously.

[0388] The techniques and apparatus described herein include, but are not limited to, the following enumerated examples:

[0389] Al. A method, in a user equipment (UE) or other wireless terminal operating in a wireless network, the method comprising: determining that a Layer 1 / Layer 2 - triggered mobility (LTM) cell switch triggered by an LTM cell switch command has been successfully executed; and, transmitting a report of the successful LTM cell switch, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0390] A2. The method of example embodiment Al, wherein determining that the LTM cell switch has been successfully executed is based on at least one of: an indication sent from a first protocol layer in the UE or other wireless terminal to another protocol layer; an indication received from the wireless network; and a transmission by the UE or other wireless terminal to the wireless network.

[0391] A3. The method of example embodiment Al or A2, wherein the method comprises: logging information for the report upon determining that the LTM cell switch has been successfully executed; and subsequently transmitting the report.

[0392] A4. The method of any one of example embodiments A1-A3, wherein the report comprises one or more information elements indicated in a reporting configuration previously received by the UE or other wireless terminal.

[0393] A5. The method of example embodiment A4, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to the successful LTM cell switch, the one or more conditions comprising any one or more of any of: a value or threshold for an LTM execution supervision timer; a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch; a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0394] A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH); a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0395] A6. The method of any one of example embodiments A1-A5, wherein said transmitting is performed in response to receiving a request for the report. A7. The method of example embodiment A6, wherein the method comprises transmitting an indication that the report is available, prior to receiving said request for the report.

[0396] A8. A method performed by a user equipment, UE, operating in a wireless network, the method comprising: determining that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, logging information related to the successful execution of the LTM cell switch; and transmitting a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

[0397] A9. A method according to embodiment A8, wherein the UE receives the LTM cell switch command and a Physical Downlink Control Channel, PDCCH, addressing an identifier of the UE assigned to be used in the LTM candidate cell indicated in the LTM cell switch command, and wherein the UE considers the LTM cell switch procedure successful upon reception of the PDCCH.

[0398] A10. A method according to any one of embodiments A8 or A9, wherein the information related to the successful execution of the LTM cell switch comprises one or more fields the UE received in the LTM cell switch command associated to the successful LTM cell switch report.

[0399] All. A method according to embodiment A10, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE received in the LTM cell switch command comprises information relating to a Timing Advance Command.

[0400] A12. A method according to any one of embodiments A10 or All, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE received in the LTM cell switch command comprises information related to an indication of a target beam indicated in the LTM cell switch command. A13. The method of any one of example embodiments A8-A12, wherein said transmitting is performed in response to receiving a request for the report.

[0401] A14. The method of example embodiment A13, wherein the method comprises transmitting an in

[0402] Bl. A method, in a network node operating in a wireless network, the method comprising: receiving, from a user equipment (UE) or other wireless terminal, a report of a successful LTM cell switch by the UE or other wireless terminal, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0403] B2. The method of example embodiment Bl, wherein the network node operates the cell to which the LTM cell switch was successfully made.

[0404] B3. The method of example embodiment Bl or B2, further comprising forwarding the report to a second network node.

[0405] B4. The method of any one of example embodiments B1-B3, wherein the method comprises receiving the report in response to a request for the report sent to the UE or other wireless terminal.

[0406] B5. The method of example embodiment B4, wherein the method comprises receiving, from the UE or other wireless terminal, an indication that the report is available and sending the request for the report in response to said indication.

[0407] B6. The method of any one of example embodiments B1-B5, wherein the method comprises sending, to a UE or other wireless terminal, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch, the one or more conditions comprising any one or more of any of: a value or threshold for an LTM execution supervision timer; a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch; a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0408] A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH); a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0409] B7. A method, in a network node operating in a wireless network, the method comprising: sending, to a UE or other wireless terminal served by the network node, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch, the one or more conditions comprising any one or more of any of: a value or threshold for an LTM execution supervision timer; a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch; a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0410] A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH); a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0411] B8. The method of example embodiment B7, further comprising subsequently receiving, from a second network node, a report of a successful LTM cell switch by the UE or other wireless terminal.

[0412] B9. The method of example embodiment B8, wherein the report comprises any one or more of any of: one or more fields received in an LTM cell switch command triggering the successful LTM cell switch; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0413] Cl. A user equipment, UE, configured for Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the UE comprising: communication interface circuitry configured to communicate with a RAN node via at least one serving cell; and processing circuitry operably coupled to the communication interface circuitry, wherein the processing circuitry and communication interface circuitry are configured to: determine that a Layer 1 / Layer 2 - triggered mobility (LTM) cell switch triggered by an LTM cell switch command has been successfully executed; and, transmit a report of the successful LTM cell switch, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0414] C2. The UE of example embodiment Cl, wherein the processing circuitry and communication interface circuitry are further configured to perform operations corresponding to any of the methods of example embodiments A2-A7.

[0415] C3. A user equipment, UE, adapted for Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the UE being further adapted to: determine that a Layer 1 / Layer 2 - triggered mobility (LTM) cell switch triggered by an LTM cell switch command has been successfully executed; and, transmit a report of the successful LTM cell switch, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0416] C4. The UE of example embodiment C3, being further adapted to perform operations corresponding to any of the methods of example embodiments A2-A7. C5. A user equipment, UE, for operating in a wireless network, the UE comprising: communication interface circuitry configured to communicate with the wireless network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the UE is configured to: determine that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, log information related to the successful execution of the LTM cell switch; and transmit a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the processing circuitry considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

[0417] C6. The UE of example embodiment C5, wherein the processing circuitry and communication interface circuitry are further configured to perform operations corresponding to any of the methods of example embodiments A9-A14.

[0418] C7. A user equipment, UE, for operating in a wireless network, adapted to: determine that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, log information related to the successful execution of the LTM cell switch; and transmit a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

[0419] C8. The UE of example embodiment C7, being further adapted to perform operations corresponding to any of the methods of example embodiments A9-A14.

[0420] C9. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a user equipment, UE, configured for Ll / L2-triggered mobility, LTM, in a radio access network, RAN, configure the UE to perform operations corresponding to any of the methods of example embodiments A1-A14.

[0421] CIO. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a user equipment, UE, configured for Ll / L2-triggered mobility, LTM, in a radio access network, RAN, configure the UE to perform operations corresponding to any of the methods of example embodiments A1-A14.

[0422] DI. A network node configured to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the network node comprising: communication interface circuitry configured to communicate with one or more user equipments, UEs, via at least one serving cell; and processing circuitry operably coupled to the communication interface circuitry, wherein the processing circuitry and communication interface circuitry are configured to: receive, from a user equipment (UE) or other wireless terminal, a report of a successful LTM cell switch by the UE or other wireless terminal, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0423] D2. The network node of example embodiment DI, wherein the processing circuitry and communication interface circuitry are configured to carry out a method according to any one of example embodiments B2-B6.

[0424] D3. A network node adapted to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the network node being further adapted to: receive, from a user equipment (UE) or other wireless terminal, a report of a successful LTM cell switch by the UE or other wireless terminal, the report comprising any one or more of any of: one or more fields received in the LTM cell switch command; information associated to one or more serving cell(s) from which the UE received the LTM cell switch command; information about a target candidate cell indicated in the LTM cell switch command; information about one or more LTM candidate cell other than the target candidate cell indicated in the LTM cell switch command; information characterizing the performance of the LTM cell switch associated to the successful LTM cell switch report; information indicating a cause of the successful LTM cell switch report being logged.

[0425] D4. The network node of example embodiment DI, wherein the network node is adapted to carry out a method according to any one of example embodiments B2-B6.

[0426] D5. A network node configured to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the network node comprising: communication interface circuitry configured to communicate with one or more user equipments, UEs, via at least one serving cell; and processing circuitry operably coupled to the communication interface circuitry, wherein the processing circuitry and communication interface circuitry are configured to: sending, to a UE or other wireless terminal served by the network node, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch, the one or more conditions comprising any one or more of any of: a value or threshold for an LTM execution supervision timer; a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch; a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0427] A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH); a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0428] D6. The network node of example embodiment DI, wherein the processing circuitry and communication interface circuitry are configured to carry out a method according to B8 or B9.

[0429] D7. A network node adapted to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, the network node being further adapted to: send, to a user equipment, UE, or other wireless terminal served by the network node, a reporting configuration for reporting a successful LTM cell switch, wherein the reporting configuration comprises one or more conditions for logging one or more respective information elements related to successful LTM cell switch, the one or more conditions comprising any one or more of any of: a value or threshold for an LTM execution supervision timer; a flag indicating logging of the information element or elements if the UE or other wireless terminal falls back from a RACH-less LTM cell switch to a RACH based LTM cell switch; a flag indicating logging of the information element or elements if the user plane interruption time is above / below a certain threshold;

[0430] A flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a LI mobility indication (DCI indication in PDCCH); a flag indicating logging of the information element or elements if the UE received the LTM cell switch command via a L2 (MAC CE) mobility indication; a list of cells such that if the successful LTM cell switch is performed towards one of the listed cells, the information element or elements are logged; and a list of beam indexes such that if the UE performed LTM cell switch towards a beam identified by one of the listed beam indexes, the information element or elements are logged.

[0431] D8. The network node of example embodiment DI, wherein the network node is adapted to carry out a method according to example embodiment B8 or B9.

[0432] D9. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a network node configured to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, configure the network node to perform operations corresponding to any of the methods of example embodiments B1-B9.

[0433] DIO. A computer-readable medium comprising, stored thereupon, a computer program product comprising computer-executable instructions that, when executed by processing circuitry of a network node configured to support Ll / L2-triggered mobility, LTM, in a radio access network, RAN, configure the network node to perform operations corresponding to any of the methods of example embodiments B1-B9.

[0434] Some abbreviations:

[0435] BFI Beam Failure Indication

[0436] BFR Beam Failure Recovery BWP Bandwidth Part

[0437] CE Control Element

[0438] CBRA Contention Based Random Access

[0439] CFRA Contention Free Random Access

[0440] CHO Conditional Handover

[0441] CP Control Plane

[0442] C-RNTI Cell- Radio Network Temporary Identifier.

[0443] CSI Channel State Information

[0444] CSI-RS Channel State Information - Reference Signal

[0445] CU Central unit

[0446] CU-gNB gNB-CU

[0447] DCI Downlink Control Information

[0448] DL Downlink

[0449] DRB Data Radio Bearer

[0450] DU Distributed unit eNB Base station supporting the LTE air interface gNB Base station supporting the NR air interface gNB-CU gNB Central Unit gNB-DU gNB Distributed Unit

[0451] HARQ. Hybrid Automatic Repeat Request

[0452] HOF Handover Failure

[0453] IE Information Element

[0454] LI Layer-1

[0455] L2 Layer-2

[0456] L3 Layer-3

[0457] LTE Long Term Evolution

[0458] LTM Layer 1 / Layer 2 (Ll / L2)-Triggered Mobility

[0459] MAC Medium Access Control

[0460] MDT Minimization of Drive Test

[0461] MHI Mobility History Report

[0462] MCG Master Cell Group

[0463] MN Master Node

[0464] NR New Radio

[0465] PCell Primary Cell PCI Physical cell identifier

[0466] PDCCH Physical Downlink Control Channel

[0467] PSCell Primary Secondary Cell

[0468] PRACH Physical Random Access Channel

[0469] QCI Quality of Service Class Indicator

[0470] RA Random Access

[0471] RACH Random Access Channel

[0472] RACH based Random Access Channel based

[0473] RACH-less Random Access Channel Less (i.e., without RA procedure)

[0474] RAN Radio Access Network

[0475] RAT Radio Access Technology

[0476] RLF Radio Link Failure

[0477] RRC Radio Resource Control

[0478] RSRP Received Signal Received Power

[0479] RSRQ Received Signal Received Quality

[0480] RSSI Received Signal Strength Indicator

[0481] SCell Secondary Cell

[0482] S / U supplementary uplink / uplink

[0483] SCG Secondary Cell Group

[0484] S-DU Source Distributed Unit

[0485] S-gNB-DU Source-gNB-Distributed Unit

[0486] SINR Signal to Interference Noise ratio

[0487] SN Secondary Node

[0488] SpCell Special Cell

[0489] SSB Synchronization Signal / PBCH block (SSB)

[0490] SS / PBCH Synchronization Signal / Physical Broadcast Channel

[0491] SS-RSRP Synchronization Signal-Received Signal Received Power

[0492] SS-RSRQ Synchronization Signal-Received Signal Received Quality

[0493] SS-SINR Synchronization Signal-Signal To Interference Noise Ratio

[0494] TA Time Advance

[0495] TCI Transmission Configuration Indicator

[0496] UE User Equipment

[0497] UL Uplink

[0498] WLAN AP wireless local-area network Access Point

Claims

CLAIMS1. A method performed by a user equipment, UE, operating in a wireless network, the method comprising: determining (510) that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, logging (512) information related to the successful execution of the LTM cell switch; and transmitting (520) a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the UE considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

2. A method according to claim 1, wherein the UE receives the LTM cell switch command and a Physical Downlink Control Channel, PDCCH, addressing an identifier of the UE assigned to be used in the LTM candidate cell indicated in the LTM cell switch command, and wherein the UE considers the LTM cell switch procedure successful upon reception of the PDCCH.

3. A method according to any one of claims 1 or 2, wherein the information related to the successful execution of the LTM cell switch comprises one or more fields the UE received in the LTM cell switch command associated to the successful LTM cell switch report.

4. A method according to claim 3, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE received in the LTM cell switch command comprises information relating to a Timing Advance Command.

5. A method according to any one of claims 3-4, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE received in the LTM cell switch command comprises information related to an indication of a target beam indicated in the LTM cell switch command.

6. A method according to any one of claims 1-5, wherein the UE transmits the successful LTM cell switch report to the network node in response to receiving (516) a request for successful LTM cell switch report from the network node.

7. A method according to claim 6, wherein prior to receiving the request for successful LTM cell switch report, the UE transmits an indication of availability of a successful LTM cell switch report.

8. A user equipment, UE, (900) for operating in a wireless network, the UE (900) comprising: communication interface circuitry (912) configured to communicate with the wireless network; and processing circuitry (902) operatively coupled to the communication interface circuitry (912), whereby the UE (900) is configured to: determine that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, log information related to the successful execution of the LTM cell switch; and transmit a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the processing circuitry (902) considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

9. A UE (900) according to claim 8, wherein the UE (900) is configured to receive the LTM cell switch command and a Physical Downlink Control Channel, PDCCH, addressing an identifier of the UE assigned to be used in the LTM candidate cell indicated in the LTM cell switch command, and wherein the UE (900) is further configured to consider the LTM cell switch procedure successful upon reception of the PDCCH.

10. A UE (900) according to any one of claims 8 or 9, wherein the information related to the successful execution of the LTM cell switch comprises one or more fields the UE (900) received in the LTM cell switch command associated to the successful LTM cell switch report.

11. A UE (900) according to claim 10, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE (900) received in the LTM cell switch command comprises information relating to a Timing Advance Command.

12. A UE (900) according to any one of claims 10 or 11, wherein the information related to the successful execution of the LTM cell switch which comprises one or more fields the UE (900) received in the LTM cell switch command comprises information related to an indication of a target beam indicated in the LTM cell switch command.

13. A UE (900) according to any one of claims 8-12, wherein the UE (900) is configured to transmit the successful LTM cell switch report to the network node in response to a request for successful LTM cell switch report from the network node.

14. A UE (900) according to claim 13, wherein the UE (900) is configured to transmit an indication of availability of a successful LTM cell switch report.

15. A UE (900) for operating in a wireless network, adapted to: determine that a Layer 1 / Layer 2 - triggered mobility, LTM, cell switch triggered by an LTM cell switch command has been successfully executed; upon determining that the execution of the LTM cell switch is successful, log information related to the successful execution of the LTM cell switch; and transmit a successful LTM cell switch report to a network node, the LTM cell switch report including the information related to the successful execution of the LTM cell switch from a serving cell to an LTM candidate cell, wherein the UE (900) considers the execution of the LTM cell switch to the LTM candidate cell a successful LTM execution in response to receiving a downlink message that is not a Random Access message from the network.

16. A UE (900) according to claim 15, wherein the UE is adapted to carry out a method according to any one of claims 2-7.

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