Reporting l1 / l2-triggered mobility (LTM) information in conjunction with a radio-related failure

Abstract

Embodiments described herein related to methods and apparatus for reporting L1 / L2-triggered mobility (LTM) information in conjunction with a radio-related failure. A method for a UE configured to operate in a radio access network, the method comprises: receiving one or more configurations associated with respective one or more LTM candidate cells; subsequently detecting a radio-related failure while operating in the RAN; in response to detecting the radio- related failure, logging a failure report information about the radio-related failure, the logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations; and sending to a RAN node a message that includes the failure report.

Description

[0001] REPORTING L1 / L2-TRIGGERED MOBILITY (LTM) INFORMATION IN CONJUNCTION WITH A RADIO-RELATED FAILURE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to wireless networks, and more specifically to techniques for improving mobility of user equipment (UEs) across multiple cells in a radio access network (RAN) by reporting layer- 1 (LI) or layer-2 (L2) triggered inter-cell mobility (LTM) information in conjunction with radio-related failures (e.g., radio link failure, handover failure).

[0004] BACKGROUND

[0005] Currently the fifth generation (5G) of cellular systems is being standardized within the Third-Generation Partnership Project (3GPP). 5G is developed for maximum flexibility to support many different use cases including 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 gNodeB’s (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] Although not shown, in some deployments the 5GC can be replaced by an Evolved Packet Core (EPC, 198), which conventionally has been used together with a 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 the EPC via respective Sl-C interfaces and to one or more Serving Gateways (SGWs) in EPC via respective NG-U interfaces.

[0008] 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. The NG-RAN is layered into a Radio Network Layer (RNL) and a Transport Network Layer (TNL). The NG-RAN logical nodes and interfaces between them, is defined as part of the RNL. For each NG-RAN interface (NG, Xn, Fl) the related TNL protocol and the functionality are specified. The TNL provides services for user plane transport and signaling transport.

[0009] 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.

[0010] 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, each gNB-DU can be connected to only one 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.

[0011] 3 GPP Rel-10 introduced support for channel bandwidths larger than 20 MHz in LTE networks. To remain compatible with UEs from earlier releases (e.g., LTE Rel-8), a wideband LTE Rel-10 carrier appears as multiple component carriers (CCs), each having the same structure as an LTE Rel-8 carrier. A Rel-10 UE can receive the multiple CCs based on Carrier Aggregation (CA). The CCs can also be considered “cells,” such that a UE in CA has one primary cell (PCell) and one or more secondary cells (SCells) that are referred to collectively as a “cell group.” LTE Rel-12 introduced dual connectivity (DC) whereby a UE is connected simultaneously to a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG). NR includes support for CA and DC in Rel-15 and thereafter.

[0012] Self-Organizing Networks (SON) is an automation technology used to improve the planning, configuration, management, optimization, and healing of mobile RANs. SON features can broadly be categorized as either self-optimization or self-configuration, and are described in 3GPP TS 38.300 (vl7.6.0) for NR networks and in 3GPP TS 36.300 (vl7.5.0) for LTE networks.

[0013] Seamless mobility is a key feature of 3GPP radio access technologies (RATs). In general, a RAN (e.g., NG-RAN) configures a UE to perform and report radio resource management (RRM) measurements to assist network-controlled mobility decisions, such as for handover from a serving cell to a neighbor cell. Seamless handovers ensure that the UE moves around in the coverage area of different cells without excessive interruption to data transmission. However, there will be scenarios when the network fails to handover the UE to the “correct” neighbor cell in time, which can cause the UE to declare radio link failure (RLF) or handover failure (HOF). This can occur before the UE sends a measurement report in a source cell, before the UE receives a handover command to a target cell, shortly after the UE executes a successful handover to the target cell, or upon a HOF to the target cell (e.g., upon expiry of timer T304, started when the UE starts synchronization with the target cell).

[0014] An RLF reporting procedure was introduced as part of the mobility robustness optimization (MRO) in LTE Rel-9. In this procedure, a UE logs relevant information at the time of RLF and later reports such information to the network via a target cell to which the UE ultimately connects (e.g., after reestablishment). The reported information can include RRM measurements of various neighbor cells prior to the mobility operation (e.g., handover). Based on the RLF report from the UE and knowledge about the cell in which cell did the UE reestablished its connection, the RAN node serving the source cell in which the RLF occurred can determine whether it was caused due to a coverage hole or due to configuration of handover-related parameters. If due to handover-related parameters, the RAN node can classify the failure as too- early handover, too-late handover, or handover to wrong cell classes. For example, a handover could be classified as too early or to wrong cell if the UE declares failure in the target cell shortly after successfully completing the mobility operation from source cell towards the target cell.

[0015] Handovers generally can be considered “break-before-make” since the UE’s connection to its source cell is released before the UE’s connection to the target cell is established. As such, handovers involve a short interruption (e.g., 10-40 ms) during which no data can be exchanged between UE and network. To shorten this interruption time, a “make-before-break” Dual Active Protocol Stacks (DAPS) handover was introduced for NR and LTE in Rel-16. In DAPS handover, the UE maintains a connection with the source cell while the connection to the target is established. DAPS handover reduces the interruption but comes at the cost of increased UE complexity, since the UE must simultaneously receive from / transmit to source and target cells.

[0016] As specified in 3 GPP document RP-213565: Further NR Mobility Enhancement, NR Rel-18 includes a Work Item on NR mobility enhancements, including in the technical area of L1 / L2 based inter-cell mobility, also referred to as L1 / L2 triggered mobility (LTM). 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 PSCell (e.g., when dual connectivity is configured), as well as release / add SCells (e.g., when CA is configured).

[0017] Currently, all 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. Thus, a goal of Rel-18 L1 / L2 mobility enhancements is to facilitate serving cell changes via L1 / L2 signaling to address these problems and / or difficulties. SUMMARY

[0018] Once LTM has been standardized and implemented in UEs and RANs, a RAN node may instruct a UE to perform a cell change either via LTM or via a conventional layer-3 (L3) mobility operation such as handover (HO). When a UE declares failure after successfully completing such a cell change, however, the RLF related information conventionally stored by the UE does not enable a RAN node serving the UE’ s source cell to determine whether the UE’ s successful cell change was in response to an LTM cell switch command or an L3 mobility command (e.g., HO command). Since a UE may be configured with configurations for both LTM and L3 mobility, this ambiguity can hinder the RAN node’s determination of which configuration parameters for the source cell need to be adjusted.

[0019] An object of embodiments of the present disclosure is to improve reporting of handover related RLFs by UEs and usage of such information to improve RAN operation, such as by providing, enabling, and / or facilitating solutions to overcome exemplary problems summarized above and described in more detail below.

[0020] Embodiments include methods e.g., procedures) for a UE configured to operate in a radio access network (RAN, e.g., E-UTRAN, NG-RAN).

[0021] These exemplary methods include receiving from the RAN one or more configurations associated with respective one or more LTM candidate cells. These exemplary methods also include subsequently detecting a radio-related failure while operating in the RAN. These exemplary methods also include, in response to detecting the radio-related failure, logging in a failure report information about the radio-related failure. The logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. These exemplary methods also include sending to a RAN node a message that includes the failure report.

[0022] In some embodiments, these exemplary methods also include the following operations:

[0023] • storing the received one or more LTM candidate cell configurations;

[0024] • receiving from the RAN a command to execute the mobility procedure from a source cell to a target cell; and

[0025] • executing the mobility procedure in accordance with the command,

[0026] The radio-related failure is detected during execution of the mobility procedure or in the target cell after successful completion of the mobility procedure.

[0027] In some of these embodiments, the mobility procedure is an L3 mobility procedure. In other of these embodiments, the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells. In some of these embodiments, the RAN node serves a further cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0028] In some of these embodiments, the logged information includes one or more of the following:

[0029] • a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure;

[0030] • an identity of the source cell in which the command was received (;

[0031] • an identity of the UE’s last serving primary cell (PCell);

[0032] • a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure;

[0033] • a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure;

[0034] • a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure;

[0035] • a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and

[0036] • a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0037] In some variants of these embodiments, when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the logged information also includes one or more of the following:

[0038] • a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command;

[0039] • an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE;

[0040] • an eighth indication of a cell type for the first LTM candidate cell;

[0041] • a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch;

[0042] • a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and

[0043] • an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure. Other embodiments include exemplary methods (e.g., procedures) for a RAN node configured to serve UEs via a source cell. In general, these exemplary methods can be complementary to the exemplary methods for a UE summarized above.

[0044] These exemplary methods can include sending to a UE one or more configurations associated with respective LTM candidate cells. These exemplary methods also include receiving a message including a failure report about a radio-related failure detected by the UE. The failure report includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. These exemplary methods also include, based on the failure report, performing one or more adjustments to the source cell.

[0045] In some embodiments, these exemplary methods also include sending to the UE a command to execute the mobility procedure from the source cell to a target cell. The radio-related failure occurred during UE execution of the mobility procedure or in the target cell after successful UE completion of the mobility procedure.

[0046] In some of these embodiments, the mobility procedure is an L3 mobility procedure. In some variants of these embodiments, the command is sent by a centralized unit (CU) of the RAN node. In other of these embodiments, the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells. In some variants of these embodiments, the command is sent by a distributed unit (DU) of the RAN node.

[0047] In some of these embodiments, the message is received from a second RAN node that serves a cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0048] In various embodiments, the failure report can include any of the logged information summarized above in relation to UE embodiments.

[0049] Other embodiments include UEs (e.g., wireless devices) and RAN nodes (e.g., base stations, eNBs, gNBs, ng-eNBs, etc.) configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments include non-transitory, computer- readable media storing program instructions that, when executed by processing circuitry, configure such UEs and RAN nodes to perform operations corresponding to any of the exemplary methods described herein.

[0050] According to a first aspect of the invention there is provided a method for a user equipment configured to operate in a radio access network. The method comprises receiving from the RAN one or more configurations associated with respective one or more layer-1 (LI) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells. The method further comprises subsequently detecting a radio-related failure while operating in the RAN. The method further comprises in response to detecting the radio-related failure, logging in a failure report information about the radio-related failure. The logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. The method further comprises sending to a RAN node a message that includes the failure report.

[0051] According to an embodiment of the first aspect, the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

[0052] According to an embodiment of the first aspect, the method further comprises storing the received one or more LTM candidate cell configurations; receiving from the RAN a command to execute the mobility procedure from a source cell to a target cell; and executing the mobility procedure in accordance with the command. The radio-related failure is detected during execution of the mobility procedure or in the target cell after successful completion of the mobility procedure.

[0053] According to an embodiment of the first aspect, the logged information includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radiorelated failure; a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radiorelated failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0054] According to an embodiment of the first aspect, when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the logged information also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

[0055] According to an embodiment of the first aspect, the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

[0056] According to an embodiment of the first aspect, when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0057] According to an embodiment of the first aspect, the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

[0058] According to an embodiment of the first aspect, the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0059] According to an embodiment of the first aspect, the method further comprises: sending to the RAN node an indication that the UE has generated the failure report; and receiving from the RAN node a request for the failure report. The message is sent to the RAN node in response to the request.

[0060] According to a second aspect of the invention, there is provided a method for a radio access network node configured to serve user equipment via a source cell. The method comprises sending to a UE one or more configurations associated with respective one or more layer-1 (LI) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells. The method further comprises receiving a message including a failure report about a radio-related failure detected by the UE. The failure report includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. The method further comprises based on the failure report, performing one or more adjustments to the source cell. According to an embodiment of the second aspect, the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

[0061] According to an embodiment of the second aspect, the method further comprises sending to the UE a command to execute the mobility procedure from the source cell to a target cell. The radio-related failure occurred during UE execution of the mobility procedure or in the target cell after successful UE completion of the mobility procedure.

[0062] According to an embodiment of the second aspect, the message is received from a second RAN node that serves a cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0063] According to an embodiment of the second aspect, the failure report includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure; a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0064] According to an embodiment of the second aspect, performing one or more adjustments to the source cell comprises: when the first indication indicates that the mobility procedure was an LTM cell switch, adjusting by a distributed unit (DU) of the RAN node one or more parameters that affect LTM cell switches from the source cell served by the DU; and when the first indication indicates that the mobility procedure was an L3 mobility procedure, adjusting by a centralized unit (CU) of the RAN node one or more parameters that affect L3 mobility procedures from the source cell served by the CU.

[0065] According to an embodiment of the second aspect, when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the failure report also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

[0066] According to an embodiment of the second aspect, performing one or more adjustments to the source cell comprises, based on one or more of the fourth, ninth, tenth, and eleventh indications, adjusting a timing of when UEs served by the source cell are provided LTM candidate cell configurations for at least the first LTM candidate cell.

[0067] According to an embodiment of the second aspect, the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

[0068] According to an embodiment of the second aspect, when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0069] According to an embodiment of the second aspect, the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

[0070] According to an embodiment of the second aspect, the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0071] According to an embodiment of the second aspect, the method further comprises receiving from the UE an indication that the UE has generated the failure report; and sending to the UE a request for the failure report. The message is received from the UE in response to the request.

[0072] According to a third aspect of the invention, there is provided a user equipment (UE) configured to operate in a radio access network (RAN). The UE comprises communication interface circuitry configured to communicate with at least one RAN node; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments of the first aspect of the invention.

[0073] According to a fourth aspect of the invention, there is provided a user equipment (UE) configured to operate in a radio access network (RAN), the UE being further arranged to perform operations corresponding to the methods of any of embodiments of the first aspect of the invention.

[0074] According to a fifth aspect of the invention, there is provided a non-transitory, computer- readable medium storing computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radio access network (RAN), configure the UE to perform operations corresponding to the methods of any of embodiments of the first aspect of the invention.

[0075] According to a sixth aspect of the invention, there is provided a computer program product comprising computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radio access network (RAN), configure the UE to perform operations corresponding to the methods of any of embodiments of the first aspect of the invention.

[0076] According to a seventh aspect of the invention, there is provided a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell. The RAN node comprises communication interface circuitry configured to communicate with UEs via the source cell; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments of the second aspect of the invention.

[0077] According to an eighth aspect of the invention, there is provided a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the RAN node being further arranged to perform operations corresponding to the methods of any of embodiments of the second aspect of the invention.

[0078] According to a ninth aspect of the invention, there is provided a non-transitory, computer- readable medium storing computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of embodiments of the second aspect of the invention.

[0079] According to a tenth aspect of the invention, a computer program product comprising computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of embodiments of the second aspect of the invention.

[0080] These and other embodiments described herein can provide various advantages, benefits, and / or solutions to problems. For example, based on content of a failure report about a radiorelated by a UE, a RAN node can determine whether the UE was configured with LTM candidate cell configuration(s) at the time of the radio-related failure and if so, whether an LTM cell switch led to the radio-related failure. Moreover, based on an indication of whether the radio-related failure was associated with an LTM cell switch or an L3 mobility procedure, the RAN node can determine whether to send the report to a source DU (e.g., for LTM adjustment / optimization) or to a source CU / CU-CP (e.g., for L3 mobility adjustment / optimization). Furthermore, based on an indication of how long ago a UE had received its stored LTM candidate cell configuration(s), embodiments may enable the RAN to configure UEs more closely in time to when LTM candidate cell configurations are needed. At a high level, embodiments may improve UE mobility in RANs.

[0081] These and other objects, features, and advantages of embodiments of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

[0082] BRIEF DESCRIPTION OF THE DRAWINGS

[0083] For a better understanding of the embodiments of the present disclosure, and to show how it may be put into effect, reference will now be made, by way of example only, to the accompanying drawings in which:

[0084] Figures 1-2 illustrate two high-level views of an exemplary 5G / NR network architecture.

[0085] Figure 3 shows an exemplary configuration of NR user plane (UP) and control plane (CP) protocol stacks.

[0086] Figure 4 is a block diagram illustrating self-organization network (SON) functionality.

[0087] Figures 5A-B show an exemplary ASN.1 data structure for a UEInformationResponse message sent by a UE, according to various embodiments of the present disclosure.

[0088] Figure 6 shows a flow diagram of an exemplary method for a UE (e.g., wireless device), according to various embodiments of the present disclosure.

[0089] Figure 7 shows a flow diagram of an exemplary method for a RAN node (e.g., base station, eNB, gNB, ng-eNB, etc.), according to various embodiments of the present disclosure.

[0090] Figure 8 shows a communication system according to various embodiments of the present disclosure.

[0091] Figure 9 shows a UE according to various embodiments of the present disclosure. Figure 10 shows a network node according to various embodiments of the present disclosure.

[0092] Figure 11 shows host computing system according to various embodiments of the present disclosure.

[0093] Figure 12 is a block diagram of a virtualization environment in functions implemented by some embodiments of the present disclosure may be virtualized.

[0094] 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.

[0095] Figure 14 shows a signaling diagram illustrating an example implementation of the methods of Figure 6 and Figure 7.

[0096] DETAILED DESCRIPTION

[0097] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0098] In general, all terms used herein are to be interpreted according to their ordinary meaning to a person of ordinary skill in the relevant technical field, unless a different meaning is expressly defined and / or implied from the context of use. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise or clearly implied from the context of use. The operations of any methods and / or procedures disclosed herein do not have to be performed in the exact order disclosed, unless an operation is explicitly described as following or preceding another operation and / or where it is implicit that an operation must follow or precede another operation. Any feature of any embodiment disclosed herein can apply to any other disclosed embodiment, as appropriate. Likewise, any advantage of any embodiment described herein can apply to any other disclosed embodiment, as appropriate.

[0099] Furthermore, the following terms are used throughout the description given below:

[0100] • Radio Access Node: As used herein, a “radio access node” (or equivalently “radio network node,” “radio access network node,” or “RAN node”) can be any node in a radio access network (RAN) that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., gNB in a 3 GPP 5G / NR network or an enhanced or eNB in a 3GPP LTE network), base station distributed components (e.g., CU and DU), a high-power or macro base station, a low-power base station (e.g., micro, pico, femto, or home base station, or the like), an integrated access backhaul (IAB) node, a transmission point (TP), a transmission reception point (TRP), a remote radio unit (RRU or RRH), and a relay node.

[0101] • Core Network Node: As used herein, a “core network node” is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a serving gateway (SGW), a PDN Gateway (P-GW), a Policy and Charging Rules Function (PCRF), an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a Charging Function (CHF), a Policy Control Function (PCF), an Authentication Server Function (AUSF), a location management function (LMF), or the like.

[0102] • Wireless Device: As used herein, a “wireless device” (or “WD” for short) is any type of device that is capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Communicating wirelessly can involve transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information through air. Unless otherwise noted, the term “wireless device” is used interchangeably herein with the term “user equipment” (or “UE” for short), with both of these terms having a different meaning than the term “network node”.

[0103] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0104] • Network Node: As used herein, a “network node” is any node that is either part of the radio access network (e.g., a radio access node or equivalent term) or of the core network (e.g., a core network node discussed above) of a cellular communications network. Functionally, a network node is equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a wireless device and / or with other network nodes or equipment in the cellular communications network, to enable and / or provide wireless access to the wireless device, and / or to perform other functions (e.g., administration) in the cellular communications network.

[0105] • Node: As used herein, the term “node” (without prefix) can be any type of node that can in or with a wireless network (including RAN and / or core network), including a radio access node (or equivalent term), core network node, or wireless device. However, the term “node” may be limited to a particular type (e.g., radio access node, IAB node) based on its specific characteristics in any given context. The above definitions are not meant to be exclusive. In other words, various ones of the above terms may be explained and / or described elsewhere in the present disclosure using the same or similar terminology. Nevertheless, to the extent that such other explanations and / or descriptions conflict with the above definitions, the above definitions should control.

[0106] Note that the description given herein focuses on a 3 GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system and can be applied to any communication system that may benefit from them.

[0107] Figure 2 shows an exemplary configuration of NR user plane (UP) and control plane (CP) protocol stacks between a UE (210), a gNB (220), and an AMF (230). Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Protocol (PDCP) layers between UE and gNB are common to UP and CP. PDCP provides ciphering / deciphering, integrity protection, sequence numbering, reordering, and duplicate detection for both CP and UP, as well as header compression and retransmission for UP data.

[0108] On the UP side, Internet protocol (IP) packets arrive to PDCP as service data units (SDUs), and PDCP creates protocol data units (PDUs) to deliver to RLC. The Service Data Adaptation Protocol (SDAP) layer handles quality-of-service (QoS) including mapping between QoS flows and Data Radio Bearers (DRBs) and marking QoS flow identifiers (QFI) in UL and DL packets. RLC transfers PDCP PDUs to MAC through logical channels (LCH). RLC provides error detection / correction, concatenation, segmentation / reassembly, sequence numbering, reordering of data transferred to / from the upper layers. MAC provides mapping between LCHs and PHY transport channels, LCH prioritization, multiplexing into or demultiplexing from transport blocks (TBs), hybrid ARQ (HARQ) error correction, and dynamic scheduling (in gNB). PHY provides transport channel services to MAC and handles transfer over the NR radio interface, e.g., via modulation, coding, antenna mapping, and beam forming.

[0109] On the CP side, the non-access stratum (NAS) layer between UE and AMF handles UE / gNB authentication, mobility management, and security control. RRC sits below NAS in the UE but terminates in the gNB rather than the AMF. RRC controls communications between UE and gNB at the radio interface as well as the mobility of a UE between cells in the NG-RAN. RRC also broadcasts system information (SI) and performs establishment, configuration, maintenance, and release of DRBs and Signaling Radio Bearers (SRBs) and used by UEs. Additionally, RRC controls addition, modification, and release of carrier aggregation (CA) and dual -connectivity (DC) configurations for UEs, and performs various security functions such as key management.

[0110] After a UE is powered ON it will be in the RRC IDLE state until an RRC connection is established with the network, at which time the UE will transition to RRC CONNECTED state (e.g., where data transfer can occur). The UE returns to RRC IDLE after the connection with the network is released. In RRC IDLE state, the UE’s radio is active on a discontinuous reception (DRX) schedule configured by upper layers. During DRX active periods (also referred to as “DRX On durations”), an RRQJDLE UE receives SI broadcast in the cell where the UE is camping, performs measurements of neighbor cells to support cell reselection, and monitors a paging channel on PDCCH for pages from 5GC via gNB. An NR UE in RRC IDLE state is not known to the gNB serving the cell where the UE is camping. However, NR RRC includes an RRC_INACTIVE state in which a UE is known (e.g., via UE context) by the serving gNB. RRC INACTIVE has some properties similar to a “suspended” condition used in LTE.

[0111] Figure 3 shows a logical architecture for an NG-RAN node (e.g., gNB or ng-eNB) arranged in the split CU / DU architecture, such as gNB 100 in Figure 1. This logical architecture separates the CU into CP and UP functionality, called CU-C (or CU-CP) and CU-U (or CU-UP) respectively. Furthermore, each of the NG, Xn, and Fl interfaces is split into a CP interface (e.g., NG-C) and a UP interface (e.g., NG-U). Moreover, the CU-U and CU-C can communicate via an El interface. Each DU may be connected to only one CU-C, and each CU-U may be connected to only one CU-C. However, a single DU may be connected to multiple CU-Us under the control of the same CU-C, or a single CU-U may be connected to multiple DUs under the control of the same CU-C. Note that the terms “Central Entity” and “Distributed Entity” in Figure 3 refer to physical network nodes.

[0112] As briefly mentioned above, 3 GPP Rel-12 introduced LTE dual connectivity (DC) whereby a UE is connected simultaneously to a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG). 3GPP TR 38.804 (vl4.0.0) describes various exemplary DC scenarios or configurations in which the MN and SN can apply NR, LTE, or both.

[0113] Each cell group includes one MAC entity, a set of logical channels with associated RLC entities, a primary cell (PCell or PSCell), and optionally one or more secondary cells (SCells). The term “Special Cell” (or “SpCell” for short) refers to the PCell of the MCG or the PSCell of the SCG depending on whether the UE’s MAC entity is associated with the MCG or the SCG. In non-DC operation (e.g., carrier aggregation), SpCell refers to the PCell. An SpCell is always activated and supports physical UL control channel (PUCCH) transmission and contention-based random access by UEs.

[0114] Self-Organizing Networks (SON) is an automation technology used to improve the planning, configuration, management, optimization, and healing of mobile RANs. SON functionality can broadly be categorized as either self-optimization or self-configuration. Selfoptimization employs UE and network measurements to auto-tune the RAN. This occurs when RAN nodes are in an operational state, after the node’s RF transmitter interface is switched on. Self-configuration operations include optimization and adaptation, which are typically performed before the RAN nodes are in operational state.

[0115] Self-configuration is a pre-operational process in which newly deployed RAN nodes (e.g., eNBs or gNBs) in a pre-operational state are configured by automatic installation procedures to get the necessary basic configuration for system operation. Pre-operational state generally refers to the time when the node is powered up and has backbone connectivity until the node’s RF transmitter is switched on. Self-configuration operations in pre-operational state include (A) basic setup and (B) initial radio configuration, which include the following sub-operations shown in Figure 4:

[0116] • (a-1) Configuration of IP address and detection of operations administration and maintenance (OAM);

[0117] • (a-2) Authentication of RAN node;

[0118] • (a-3) Associate to access gateway (aGW);

[0119] • (a-4) Downloading of RAN node software (SW) and operational parameters;

[0120] • (b-1) Neighbor list configuration; and

[0121] • (b-2) Coverage / capacity-related parameter configuration.

[0122] Self-optimization is a process in which UE and network measurements are used to autotune the network. This occurs when the nodes are in operational state, which generally refers to when a node’s RF transmitter interface is switched on. Self-configuration operations include optimization and adaptation, which includes the following sub-operations shown in Figure 4:

[0123] • (c-1) Neighbor list optimization; and

[0124] • (c-2) Coverage / capacity control.

[0125] Self-configuration and self-optimization features for NR networks are described in 3GPP TS 38.300 (vl7.6.0) and for LTE networks in 3GPP TS 36.300 (vl7.5.0). These features include dynamic configuration, automatic neighbor relations (ANR), mobility load balancing (MLB), mobility robustness optimization (MRO), random access channel (RACH) optimization, capacity and coverage optimization (CCO), and mobility settings change.

[0126] MLB involves coordination between two or more RAN nodes to optimize the traffic loads of their respective cells, thereby enabling a better use of radio resources available in a geographic area among served UEs. MLB can involve load-based handover of UEs between cells served by different nodes, thereby achieving “load balancing.”

[0127] CCO involves coordination between two or more RAN nodes to optimize the coverage and capacity offered by their respective cells. For example, a reduced coverage and / or capacity in a cell served by a first RAN node can be compensated by an increase in the coverage and / or capacity of neighboring cell served by a second RAN node.

[0128] Mobility settings change involves two RAN nodes negotiating a mutually agreeable value for a parameter that triggers UE handover (or other mobility operation) between neighbor cells. This parameter effectively defines a “virtual cell border” experienced by UEs based on their measurements and / or assessments, e.g., of quality and / or strength of reference signals received from the respective cells. For example, a setting change for a handover trigger parameter can expand or shrink the UE’s observed coverage area of a serving cell, thereby causing the UE to request a handover to a neighbor cell having a higher measured signal strength and / or quality.

[0129] Seamless mobility is a key feature of 3GPP radio access technologies (RATs). In general, a RAN (e.g., NG-RAN) configures a UE in RRC_CONNECTED state to perform and report radio resource management (RRM) measurements to assist network-controlled mobility decisions, such as for handover from a serving cell to a target cell. Upon the reported measurements meeting a certain condition or threshold, the serving RAN node may send a handover command to the UE, indicating a target cell for the handover. In NR, the handover command is an RRCReconfiguration message with a reconfigurationWithSync field. The procedure to perform a handover is sometimes also referred to as “L3 mobility”, as it is controlled by layer 3 (L3, i.e., RRC) and the messages exchanged are part of L3.

[0130] These reconfigurations are prepared in advance by a target RAN node serving the target cell, upon a request from the UE’s serving RAN node. This request is transmitted over the Xn interface in case the serving and target RAN nodes are part of the NG-RAN. The reconfiguration in the handover command takes into account the UE’s existing RRC configuration in its current serving cell (also referred to as “source cell”), which are provided in the inter-node request. In some cases, the reconfiguration can be provided as a “delta” to the UE’s existing configuration in the source cell, which reduces the size of the handover command.

[0131] The reconfiguration provided by the target RAN node contains all information the UE needs to access the target cell, e.g., random access configuration, a new cell radio network temporary identifier (C-RNTI) assigned to the UE in the target cell, and parameters enabling the UE to calculate security keys that it can use when communicating with the target cell (including sending a handover complete message).

[0132] In general, UE nobility in RRC CONNECTED state is network-based as the network has the most information about the current conditions such as cell loading (UEs and / or traffic), available node resources (e.g., processing), available frequencies, etc. Seamless handovers ensure that the UE moves around in the coverage area of different cells without excessive interruption to data transmission. However, there will be scenarios when the network fails to handover the UE to the “correct” neighbor cell in time, which can cause the UE will declare radio link failure (RLF) or handover failure (HOF).

[0133] A UE typically triggers an internal RLF procedure when something unexpected happens in any of these mobility-related procedures. The RLF procedure involves interactions between RRC and lower layer protocols such as PHY (or LI), MAC, RLC, etc. including radio link monitoring (RLM) on LI.

[0134] The principle of RLM is similar in LTE and NR. In general, the UE monitors link quality of the UE’s serving cell and uses that information to decide whether the UE is in-sync (IS) or out- of-sync (OOS) with respect to that serving cell. If RLM (i.e., by Ll / PHY) indicates number of consecutive OOS conditions to the RRC layer, then RRC starts an RLF procedure and declares RLF after expiry of a timer (e.g., T310). The LI RLM procedure is carried out by comparing the estimated measurements to some targets Qout and Qin, which correspond to block error rates (BLERs) of hypothetical transmissions from the serving cell. Exemplary values of Qout and Qin are 10% and 2%, respectively. In NR, the network can define RS type (e.g., CSLRS and / or SSB), exact resources to be monitored, and the BLER target for IS and OOS indications.

[0135] In case of HOF and RLF, the UE may take autonomous actions such as selecting a cell and initiating reestablishment to remain reachable by the network. In general, a UE declares RLF only when the UE realizes that there is no reliable radio link available between itself and the network, which can result in poor user experience. Also, reestablishing the connection requires signaling with a newly selected cell (e.g., random access procedure, exchanging various RRC messages, etc.), which introduces latency until the UE can again reliably transmit and / or receive user data with the network. Potential causes for RLF include:

[0136] 1) Radio link problem indicated by PHY (e.g., expiry of RLM-related timer T310);

[0137] 2) Random access problem indicated by MAC entity;

[0138] 3) Expiry of a measurement reporting timer (e.g., T312), due to not receiving a HO command from the network while the timer is running despite sending a measurement report;

[0139] 4) Reaching a maximum number of RLC retransmissions;

[0140] 5) Consistent UL LBT failures while operating in unlicensed spectrum; and

[0141] 6) Failing a beam failure recovery (BFR) procedure.

[0142] On the other hand, HOF is caused by expiry of T304 timer while performing the handover to the target cell.

[0143] Since RLF leads to reestablishment in a new cell and degradation of UE / network performance and end-user experience, it is in the interest of the network to understand the reasons for UE RLF and to optimize mobility-related parameters (e.g., trigger conditions of measurement reports) to reduce, minimize, and / or avoid subsequent RLFs. Before Rel-9 mobility robustness optimizations (MRO), only the UE was aware of radio quality at the time of RLF, the actual reason for declaring RLF, etc.

[0144] An RLF reporting procedure was introduced as part of mobility robustness optimization (MRO) in LTE Rel-9. In this procedure, a UE logs relevant information at the time of RLF and later reports such information to the network via a target cell to which the UE ultimately connects (e.g., after reestablishment). The reported information can include RRM measurements of various neighbor cells prior to the mobility operation (e.g., handover). A corresponding RLF reporting procedure was introduced as part of MRO for NR Rel-16. The UE can store the RLF report in a UE variable call varRLF-Report and retains it in memory for up to 48 hours, after which it may discard the information.

[0145] When sending certain RRC messages such as RRCReconfigurationComplete, RRCReestablishmentComplete, RRCSetup-Complete, and RRCResumeComplete, the UE can indicate it has a stored RLF report by setting a rlf-InfoAvailable field to “true.” If the gNB serving the target cell wants to receive the RLF report, it sends the UE an UEInformationRequest message with a flag “rlf-ReportReq-rl6”. In response, the UE sends the gNB an UEInformationResponse message that includes the RLF report, which can include any of the following information:

[0146] • Measurement quantities (RSRP, RSRQ) of the last serving cell (PCell).

[0147] • Measurement quantities of the neighbor cells in different frequencies of different RATs (e.g., EUTRA, UTRA, GERAN, CDMA2000).

[0148] • Measurement quantity (RS SI) associated to WLAN APs.

[0149] • Measurement quantity (RS SI) associated to Bluetooth beacons.

[0150] • Location information, if available (including location coordinates and velocity)

[0151] • Globally unique identity of the last serving cell, if available, otherwise the PCI and the carrier frequency of the last serving cell.

[0152] • Tracking area code of the PCell.

[0153] • Time elapsed since the last reception of the ‘Handover command’ message.

[0154] • C-RNTI used in the previous serving cell.

[0155] • Whether or not the UE was configured with a DRB having QCI = 1.

[0156] Based on a UE RLF report and knowledge of the cell in which the UE reestablished its connection, the RAN node serving the UE’s original source cell can deduce whether the RLF was due to a coverage hole or handover-related parameter configurations. If the latter case, the RAN node serving the UE’s original source cell can also classify the handover-related failure as too- early, too-late, or wrong-cell. These classes are described in more detail below.

[0157] The RAN node can classify a handover failure as “too late handover” when the original source cell fails to send the UE a command to handover to a particular target cell and if the UE ultimately reestablishes itself in this same target cell (i.e., post RLF). An example corrective action by the RAN node serving the UE’s original source cell is to initiate handovers towards this target cell slightly earlier, such as by decreasing the cell individual offset (CIO) towards the target cell. Note that CIO controls when the UE sends the RAN node an event-triggered measurement report that causes the RAN node to make a handover decision.

[0158] The RAN node can classify a handover failure as ‘too early handover’ when the original source cell successfully sends the UE a HO command for a particular target cell but the UE fails to perform RA towards the target cell or the UE declares RLF in the target cell soon after connection reestablishment. An example corrective action by the RAN node serving the UE’s original source cell is to initiate handovers towards this target cell slightly later, such as by increasing cell individual offset (CIO) for this target cell, which cause UEs in the source cell to send the event-triggered measurement report slightly later.

[0159] The RAN node can classify a handover failure as “wrong cell handover” when the original serving cell intends to perform the handover for this UE towards a particular target cell but the UE instead declares RLF and reestablishes its connection in a different cell, or declares RLF in the target cell soon after connection reestablishment. Example corrective actions by the RAN node serving the UE’s original source cell include initiating the UE measurement reporting procedure that leads to handover towards the target cell slightly later (e.g., by decreasing CIO for that cell) or initiating the handover towards the other cell in which the UE reestablished its connection slightly earlier (e.g., by increasing CIO for that cell).

[0160] In cases where the UE declares RLF in the target cell soon after connection reestablishment, the failure classification is aided by RLF report contents including an identifier of the source cell in which the UE had received a cell change command (previousPCelllD field) and a duration that UE stayed in the target cell prior to declaring RLF (timeConnFailure field).

[0161] NR Rel-15 introduced beam failure detection (BFD) and beam failure recovery (BFR). The serving RAN node configures a UE with BFD reference signals (e.g., SSB or CSLRS) to be monitored, and the UE declares beam failure when a quantity of beam failure indications from LI reaches a configured threshold before a configured timer expires. After BFD, the UE initiates a RA procedure in the serving cell and selects a suitable beam to perform BFR. In a multi-beam serving cell, RLF occurs when the UE is unable to find any suitable beam within the serving cell to recover the UE’s failed connection. In contrast, RLF is prevented by the UE’s successful BFR to another beam in the same cell.

[0162] 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 L3 (e.g., RSRP) measurements and involves RRC signaling to change PCell and PSCell (e.g., when dual connectivity is configured), as well as release / add SCells (e.g., when CA is configured). As specified in 3GPP document RP -213565: Further NR Mobility Enhancements, NR Rel-18 includes a Work Item on NR mobility enhancements, including in the technical area of L1 / L2 based inter-cell mobility, also referred to as L1 / L2 triggered mobility (LTM). Current L3-based inter-cell mobility procedures involve LI and L2 resets, leading to longer latency, increased signaling overhead, and longer interruptions than for intra-cell beam switching.

[0163] Thus, a goal of Rel-18 L1 / L2 mobility enhancements is to facilitate serving cell changes via L1 / L2 signaling to address these issues. Some more specific goals include specifying the following:

[0164] • Configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells;

[0165] • Dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1 / L2 signaling;

[0166] • LI enhancements for inter-cell beam management, including LI measurement and reporting, and beam indication;

[0167] • Timing Advance (TA) management; and

[0168] • CU-DU interface signaling to support L1 / L2 mobility, if needed.

[0169] These Rel-18 L1 / L2 mobility enhancements also must consider the split CU / DU architecture shown in Figures 1 and 3, including for intra-DU and inter-DU / intra-CU cell changes. In the inter-DU / intra-CU scenario, the candidate cell for LTM is a cell served by a neighbor DU to the (serving or source) DU that currently provides the UE’s PCell (or PSCell, for SCG change in DC). In the intra-DU scenario, the candidate cell for LTM is a cell served by the same DU that currently provides the UE’s PCell (or PSCell, for SCG change in DC).

[0170] In LTM a UE is pre-configured by its serving RAN with one RRC configuration per LTM candidate cell, sometimes referred to as an “LTM candidate cell configuration”. This configuration may be an RRCReconfiguration message or a portion thereof, such as one or more lEs / fields / parameters (e.g., CellGroupConfig IE). The UE performs measurements on configured LTM candidate cells and transmits corresponding measurement reports to the RAN, which triggers the execution of a LTM cell switch procedure by the UE to one of the configured LTM candidate cells. This triggering is done by transmitting an LTM cell switch command to the UE in lower layer signaling (e.g., DCI or MAC CE). Based on this command, the UE connects to the associated LTM candidate cell and uses the previously received RRC configuration for this cell.

[0171] Since one of the goals of LTM is to reduce the interruption time for UE data transmissions, the UE needs to be ready to communicate with the target cell upon (or shortly after) receiving the L1 / L2 signaling for mobility execution from the source cell. For example, the UE must be able to transmit UL data or a scheduling request (SR) to the target cell and / or monitor a DL control channel (e.g., PDCCH) from the target cell. In other words, UE needs to know the cell that it is moving to so it can apply the corresponding configuration, including the correct timing alignment and / or transmission configuration indicator (TCI) state for the cell. Likewise, when the source DU transmits the L1 / L2 signaling for mobility execution, the target DU needs to be prepared for scheduling UL and DL transmissions for the UE in the target cell, and for receiving scheduling requests (SR) from the UE.

[0172] To further reduce the interruption time and latency during LTM execution, a UE may perform early UL and / or DL synchronization with an LTM candidate cell before it receives the LTM cell switch command. For early UL synchronization, the UE obtains a Timing Advance (TA) value. This can be triggered by the network transmitting a PDCCH order to the UE in the source cell, followed by the UE transmitting a random access (RA) preamble in the LTM candidate cell indicated by the received PDCCH order. The TA value for the LTM candidate cell may be provided to the UE by the network before LTM execution. For example, the TA value may be included in a RAR (Random Access Response) to the RA preamble, a MAC control element (CE) similar to RAR, or in the LTM cell switch command.

[0173] 3GPP has also agreed to the following principles for LTM in Rel-18:

[0174] • No security update support in Rel-18 with LTM.

[0175] • RAN2 to confirm that the CellGroupConfig IE is (mandatory) needed within an LTM candidate cell configuration.

[0176] • RadioBearerConfig IE can be optionally supported in an LTM candidate configuration.

[0177] • MeasConfig IE can be optionally supported in an LTM candidate configuration.

[0178] • OtherConfig IE is not required to be part of the LTM candidate cell configuration.

[0179] • LTM candidate cell configuration should be designed as “To AddMod / ToRelease” structure.

[0180] • LTM candidate cell configuration ASN.l data structure includes at least a CellGroupConfig IE and a configuration ID.

[0181] • RRCReconfigurationComplete message is always sent after each LTM execution.

[0182] According to other 3GPP agreements, LTM can co-exist with L3 handover. For example, while a UE is configured with LTM candidate cells, the UE can also execute an L3 handover command sent by the RAN, with the RAN responsible for handling any race conditions (or conflicts) between an LTM cell switch procedure and an L3 handover).

[0183] In the split-node architecture illustrated by Figures 1 and 3, the decision to trigger an LTM cell switch procedure for a UE is made by a DU serving the UE’s source cell (also referred to as “source DU”). In contrast, the decision to trigger an L3 mobility decisions is made by a CU-CP associated with the UE’s source cell. Configurations for LTM candidate cells are provided to a UE in advance of an LTM cell switch procedure, and different UEs may have different limitations on how many LTM candidate cell configurations they can store at any given time (e.g., 8, 12, 16, etc.). Moreover, different UEs served by the same DU may store different LTM candidate cell configurations depending on their respective locations, mobility histories, mobility settings, etc.

[0184] Once LTM has been standardized and implemented in UEs and RANs, a RAN node may instruct a UE to perform a cell change either via LTM or via a conventional layer-3 (L3) mobility operation such as handover (HO). When a UE declares failure after successfully completing such a cell change, however, the RLF related information conventionally stored by the UE does not enable a RAN node serving the UE’ s source cell to determine whether the UE’ s successful cell change was in response to an LTM cell switch command or an L3 mobility command (e.g., HO command). Since a UE may be configured with configurations for both LTM and L3 mobility, this ambiguity can hinder the RAN node’s determination of which configuration parameters for the source cell need to be adjusted. Furthermore, this ambiguity also means that the target RAN node does not know whether the source DU (for LTM cell switch) or the CU- CP (for L3 mobility) should receive the UE’s reported information.

[0185] Accordingly, embodiments of the present disclosure provide flexible and efficient techniques whereby a UE logs (or stores) various LTM-related information in conjunction with declaring a radio-related failure, such as RLF or a mobility-related failure (e.g., HOF). For example, the LTM-related information can include an indication of whether the radio-related failure was associated with an LTM cell switch or an L3 mobility procedure. As another example, the LTM-related information can include an indication of whether the target cell for LTM cell switch was a PCell, a PSCell, an SCell, or a non-serving cell. Various other LTM- related information can be included, as described below. The UE then sends the logged information to the RAN in an appropriate failure report, such as an RLF report in an RRC UEInformationResponse message.

[0186] Embodiments of the present disclosure can provide various advantages, benefits, and / or solutions to problems. For example, based on content of the failure report, a RAN node can determine whether the UE was configured with LTM candidate cell configuration(s) at the time of the radio-related failure and if so, whether an LTM cell switch led to the radio-related failure. Moreover, based on an indication of whether the radio-related failure was associated with an LTM cell switch or an L3 mobility procedure, the RAN node can determine whether to send the report to a source DU (e.g., for LTM adjustment / optimization) or to a source CU / CU-CP (e.g., for L3 mobility adjustment / optimization). Furthermore, based on an indication of how long ago a UE had received its stored LTM candidate cell configuration(s), embodiments can enable the RAN to configure UEs more closely in time to when LTM candidate cell configurations are needed. At a high level, embodiments may improve UE mobility in RANs.

[0187] In the present disclosure, the following terms may be used interchangeably: “L1 / L2 based inter-cell mobility”, “L1 / L2 mobility,” “LI -mobility,” “LI based mobility,” “Ll / L2-centric inter-cell mobility,” “L1 / L2 inter-cell mobility,” “inter-cell beam management,” “inter-DU L1 / L2 based inter-cell mobility”, and “L1 / L2 triggered mobility” (or LTM). These terms refer to a scenario in which a UE receives lower layer (i.e., below RRC, such as MAC or PHY) signaling from a network indicating for the UE to change of its serving cell (e.g., PCell) from a source cell to a target cell.

[0188] The content of the lower layer signaling may be referred to as “LTM cell switch command”. Exemplary lower layer signaling includes LI DL control information (DCI) and L2 MAC control element (CE). Compared to conventional RRC signaling, lower layer signaling reduces processing time and interruption time during mobility and may also increase mobility robustness since the network can respond more quickly to changes in the UE’s channel conditions.

[0189] The term “LTM candidate cell” refers to a cell for which the UE is configured for LTM, specifically a cell the UE can move to in a LTM cell switch procedure in response to receiving an LTM cell switch command. An LTM candidate cell may also be referred to herein as “candidate cell”, “(LTM) candidate, “mobility candidate”, “non-serving cell”, “additional cell”, “(LTM) target candidate cell”, “(LTM) target candidate”, and comparable terms. A UE may perform and report measurements (e.g., CSI measurements) on an LTM candidate cell, based on which the UE’s serving RAN node may make an informed decision about which beam (or TCI state) and / or cell to switch the UE. 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). In the case of LTM fast recovery, when a failure is detected and the UE selects an LTM candidate cell, the UE performs an LTM cell switch towards the selected LTM candidate cell (e.g., by applying the associated LTM candidate cell configuration) rather than performing RRC re-establishment.

[0190] The change of serving cell (e.g., PCell) may also lead to a change in SCell(s) of the same cell group, e.g., in case an LTM cell switch command triggers the UE to change to another cell group configuration of the same type (e.g., another MCG configuration). For example, an LTM cell switch may include a change in SpCell (e.g., PCell for MCG, PSCell for SCG) and a change (e.g., addition, modification and / or release) in SCells of the same cell group. This may happen when the command triggers the UE to change to another cell group configuration of the same type (e.g., another SCG 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” via an RRCReconfiguration message. The terms “(LTM) candidate configuration”, “(LTM) candidate target cell configuration”, and “(LTM) target candidate (cell) configuration” may be used interchangeably with LTM candidate cell configuration.

[0191] An LTM candidate cell configuration may be included in an RRC IE such as CellGroupConfig, SpCellConfig, or SCellConfig and / or an embedded RRCReconfiguration message for an LTM candidate cell. An LTM candidate cell configuration includes configuration parameters the UE needs to operate in that LTM candidate cell when it performs an LTM cell switch procedure, e.g., upon reception of the LTM cell switch command. As some more specific examples, an LTM candidate cell configuration can include a PCell configuration and one or more SCell configurations of an MCG, or a PSCell configuration and one or more SCell configurations of an SCG. The exact content and / or structure of the IE and / or embedded message for an LTM candidate cell configuration may be called “RRC model for the candidate configuration” or more simply “RRC model”.

[0192] A UE may receive an LTM candidate cell configuration in complete form or as a delta (or difference) relative to a reference configuration (which may be signaled separately). In the latter case, the actual LTM candidate configuration is a combination of the delta configuration and the reference configuration.

[0193] The lower layer signaling from the RAN may include an identifier (or index) associated with an LTM candidate cell configuration. The identifier may be sent together with an LTM cell switch command, indicating for the UE to perform an LTM cell switch to the associated LTM candidate cell.

[0194] The term “LTM configuration” refers to a data structure that is used for or related to UE LTM operations, and may include one or more of the following elements (non-exclusive):

[0195] • an LTM candidate configuration, i.e., for an LTM candidate cell;

[0196] • a measurement configuration, e.g., LI measurement and reporting configuration for the LTM candidate cell;

[0197] • a configuration for DL pre-sync, e.g., for early TCI state activation;

[0198] • a configuration for UL pre-sync, e.g., for transmission of PDCCH ordered preamble transmission and reception of timing advance (TA);

[0199] • a configuration for execution of an LTM cell switch procedure according to a given LTM candidate cell configuration (e.g., whether to perform RA, RLC reestablishment, MAC reset, PDCP recovery, etc.). The term “part of an LTM configuration” may refer to a subset of the elements in the above list, and / or a subset of items comprising any of the elements present (e.g., subset of configurations for DL pre-sync).

[0200] The phrase “LTM cell switch procedure” refers to the process of a UE switching (or changing) from a source cell to a target cell (i.e., an LTM candidate cell) using LTM. An LTM cell switch procedure may also be referred to 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”. Similarly, the phrase “switching to an LTM candidate cell configuration” means that the UE applies an LTM candidate cell configuration such that the associated LTM candidate cell becomes its new special cell (SpCell, e.g., PCell for LTM in MCG or PSCell for LTM in SCG) or its new SCell. In other words, an LTM candidate cell can be a candidate for the UE’s PCell, PSCell, or SCell.

[0201] Furthermore, an LTM cell switch procedure may involve a UE switching (or changing) from a source cell group to a target cell group using LTM. For example, this may involve a change in the SpCell for a cell group (e.g., PCell for MCG, PSCell for SCG), a change in SCells of the cell group (e.g., addition, modification, and / or release of one or more SCells), and / or a swap between SpCell and SCell roles for two cells in the same cell group.

[0202] Although embodiments of the present disclosure are described in the context of RLF for PCell related handover, principles of the described embodiments are equally applicable to failures for PSCell changes, such as declaring SCG failure after performing LTM in SCG. In such case, rather than sending an RLF report, the UE sends an SCGFailurelnformation message that indicates whether the performed mobility operation was an L3 mobility procedure or an LTM cell switch. In the latter case, the UE may also indicate whether the LTM cell switch was initiated by an LI trigger (e.g., DCI) or an L2 trigger (e.g., MAC CE).

[0203] Some embodiments of the present disclosure involve procedures performed by a UE configured to operate in a RAN. The UE declares or detects a radio-related failure. At that time, the UE may be configured with one or more LTM candidate cell configurations, e.g., for respective LTM candidate cells. The radio-related failure can be an RLF, which may be due to reaching a maximum number of re-transmissions, expiration of one or more REM supervision timers (e.g., T310, T312, etc.), expiration of a LTM cell switch supervision timer, or a combination thereof.

[0204] In some embodiments, the radio-related failure can be detected during or after executing a command for the UE to perform a mobility procedure from a source cell to a target cell. In other embodiments, the radio-related failure can be detected while the UE is connected to the serving cell and is configured with one or more LTM candidate cell configurations. In any event, the UE logs (or stores) various information in conjunction with the radiorelated failure. The following are some examples of the information logged by the UE:

[0205] • an indication of whether the mobility procedure that led to the radio-related failure was an LTM cell switch or an L3 mobility procedure;

[0206] • an identity of the source cell in which the command to perform the mobility procedure that led to the failure was received by the UE;

[0207] • when the mobility procedure is an LTM cell switch, the cell in which the LTM candidate cell configuration used for the LTM cell switch was received by the UE;

[0208] • an identity of the UE’s last serving PCell;

[0209] • when the mobility procedure is an LTM cell switch, an indication of whether the target cell was the UE’s PCell, a PSCell, an SCell, or a non-serving cell;

[0210] • when the target cell for the LTM cell switch procedure is an SCell, whether the SCell is associated with the UE’s MCG or with the UE’s SCG;

[0211] • an indication of whether the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure;

[0212] • an indication of time elapsed between storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch procedure;

[0213] • an indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure;

[0214] • an indication of time elapsed between receiving the LTM candidate cell configuration used for the LTM cell switch procedure, and initiating execution of the LTM cell switch procedure;

[0215] • an indication of time elapsed between receiving the LTM candidate cell configuration used for the LTM cell switch procedure, and detecting the radio-related failure;

[0216] • an indication of whether the most recently executed LTM cell switch was performed based on one or more conditions associated with the LTM candidate cell configuration (e.g., “conditional configuration”); and

[0217] • an indication of whether the most recently executed LTM cell switch was performed in response to another failed LTM cell switch procedure (e.g., autonomously by the UE after a network triggered LTM cell switch procedure failed).

[0218] Subsequently, the UE sends the

[0219] Some embodiments can be realized as 3 GPP specifications of messages, information elements (IES), and / or fields sent by a UE and received by the RAN. Figures 5A-B show an exemplary ASN.1 data structure for an RRC UEInformationResponse message sent by a UE in response to a UEInformationRe quest message from the RAN. The RAN may send the UEInformationRequest message in response to an indication from the UE (e.g., in an RRCReconfiguration message) that the UE has logged information in a failure report. Figure 5A shows a high-level definition of IES of this message, including an rlf-Report-rl6 IE that is defined further in Figure 5B. The following table provides definitions for fields in Figure 5B that are most relevant for embodiments of the present disclosure.

[0220]

[0221] Some embodiments can be realized as procedural text in 3 GPP specifications, which specify UE and / or RAN implementation. The following text for 3GPP TS 38.331 (vl7.6.0) illustrates one example of UE determination of RLF report content according to embodiments of the present disclosure. The impact of embodiments of the present disclosure on 3GPP TS 38.331 V17.6.0 is shown in bold and underlined. Note that ellipses indicated existing portions of this section that have been omitted for conciseness.

[0222] *** Begin exemplary text for 3GPP TS 38.331 ***

[0223] 5.3.10.5 RLF report content determination

[0224] The UE shall determine the content in the VarRLF-Report as follows:

[0225] 1> clear the information included in VarRLF-Report, if any; l>set the plmn-IdentityList to include the list of EPLMNs stored by the UE (i.e., includes the RPLMN);

[0226] 1> if the failure is detected due to a LTM cell switch execution failure or while being configured with LTM cell switch configuration, set the fields in VarRLF-report as follows:

[0227] 2>set the connectionFailureType to ItmFailure:,

[0228] 2> if the LTM cell switch was initiated by a PCI indication in PDCCH;

[0229] 2> if the LTM cell switch was initiated by a MAC CE; 2> include the previousLTMCell and set it to the global cell identity and the tracking area code of the PCell where the last LTM inter-cell mobility command was received;

[0230] 2> set previousCellType to scell if the Pcell in which the failure occurred was an Scell while performing the LTM cell switch, to PSCell if the Pcell in which the failure occurred was a PSCell while performing LTM cell switch,

[0231] 2> set timeSinceLTMConfisuration to the time elapsed between receiving the last configuration of the LTM cell switch and the failure.

[0232] 1> if available, set the locationinfo as in 5.3.3.7.

[0233] The UE may discard the radio link failure information or handover failure information, i.e., release the UE variable VarRLF -Report, 48 hours after the radio link failure / handover failure is detected. NOTE 2: In this clause, the term 'handover failure' has been used to refer to 'reconfiguration with sync failure'.

[0234] *** End exemplary text for 3GPP TS 38.331 ***

[0235] In some embodiments, the UE may include in the RLF report previousPCelUD and timeConnFailure fields associated with the most recent L3 mobility procedure as well as previousL!L2Cell and timeSinceLlL2Mobility fields associated with the most recent LTM cell switch. In other embodiments, the UE only includes the pair of fields associated with the most recent mobility procedure by which the UE entered the cell in which the failure was detected - previousPCellld and timeConnFailure fields when the most recent mobility procedure was L3, or previousL!L2Cell and timeSinceLlL2Mobility fields when the most recent mobility procedure was LTM. The following text for 3GPP TS 38.331 (vl7.6.0) illustrates an example of these embodiments of the present disclosure. The impact of embodiments of the present disclosure on 3GPP TS 38.331 V17.6.0 is shown in bold and underlined. Note that ellipses indicated existing portions of this section that have been omitted for conciseness.

[0236] *** Begin exemplary text for 3GPP TS 38.331 ***

[0237] 5.3.10.5 RLF report content determination

[0238] The UE shall determine the content in the VarRLF-Report as follows:

[0239] 1> clear the information included in VarRLF-Report, if any; l>set the plmn-IdentityList to include the list of EPLMNs stored by the UE (i.e., includes the RPLMN); l>if the failure is detected due to reconfiguration with sync failure as described in 5.3.5.8.3, set the fields in VarRLF-report as follows: 2>set the connectionFailureType to hofi l>else if the failure is detected due to Mobility from NR failure as described in 5.4.3.5, set the fields in VarRLF-report as follows: 2>set the connectionFailureType to hof: l>else if the failure is detected due to radio link failure as described in 5.3.10.3, set the fields in VarRLF-report as follows:

[0240] 2>set the connectionFailureType to rlf

[0241] 2> set the rlf-Cause to the trigger for detecting radio link failure in accordance with clause 5.3.10.4;

[0242] 2>set the nrFailedPCellldm failedPCellld to the global cell identity and the tracking area code, if available, and otherwise to the physical cell identity and carrier frequency of the PCell where radio link failure is detected;

[0243] 2> if the UE had received either an RRCReconfisuration message including the reconfisurationWithSync was received before the connection failure or a L1 / L2 based inter-cell mobility command was received before the connection failure: 3> if a L1 / L2 based inter-cell mobility command was used to enter the cell in which the radio link failure was declared:

[0244] 4> include the previousLTMCell and set it to the global cell identity and the tracking area code of the PCell where the last L1 / L2 inter-cell mobility command was received;

[0245] 4>set the timeSinceLTM to the elapsed time since the execution of the last L1 / L2 inter-cell mobility command;

[0246] 3>else if the last RRCReconfiguration message including the reconfigurationWithSync concerned an intra NR handover:

[0247] 4> include the nrPreviousCell in previousPCellld and set it to the global cell identity and the tracking area code of the PCell where the last executed RRCReconfiguration message including reconfigurationWithSync was received;

[0248] 4> if the last executed RRCReconfiguration message including reconfigurationWithSync was concerning a DAPS handover: 5> set lastHO-Type to daps

[0249] 4>else if the last executed RRCReconfiguration message including reconfigurationWithSync was concerning a conditional handover: 5> set lastHO-Type to cho.:

[0250] 4> set the timeConnFailure to the elapsed time since the execution of the last RRCReconfiguration message including the reconfigurationWithSync,

[0251] 3>else if the last RRC Reconfiguration message including the reconfigurationWithSync concerned a handover to NR from E-UTRA and if the UE supports Radio Link Failure Report for Inter-RAT MRO EUTRA:

[0252] 4> include the eutraPreviousCell in previousPCellld and set it to the global cell identity and the tracking area code of the E-UTRA PCell where the last RRCReconfiguration message including reconfigurationWithSync was received embedded in E-UTRA RRC message MobilityFromEUTRACommand message as specified in TS 36.331

[0010] clause 5.4.3.3;

[0253] 4> set the timeConnFailure to the elapsed time since reception of the last RRCReconfiguration message including the reconfigurationWithSync embedded in E-UTRA RRC message MobilityFromEUTRACommand message as specified in TS 36.331

[0010] clause 5.4.3.3;

[0254] 3>if configuration of the conditional handover is available in VarConditionalReconfig at the moment of radio link failure:

[0255] 3>set choCandidateCellList to include the global cell identity and tracking area code of all the candidate target cells for conditional handover included in condRRCReconfig within VarConditionalReconfig at the time of radio link failure, excluding the candidate target cells included in measResulNeighCells,'

[0256] 2> if configuration of the conditional handover is available in VarConditionalReconfig at the moment of declaring the radio link failure:

[0257] 3> set timeSinceCHO-Reconfig to the time elapsed between the detection of the radio link failure, and the reception, in the source PCell, of the last conditionalRe configuration including the condRRCReconfig message;

[0258] 1> if connectionFailur eType is rlf and the rlf-Cause is set to randomAccessProblem or beaml'dilureRecoveryFailure or

[0259] 1> if connectionFailur eType is hof and if the failed handover is an intra-RAT handover:

[0260] 2> set the ra-InformationCommon to include the random-access related information as described in clause 5.7.10.5;

[0261] 1> if available, set the locationinfo as in 5.3.3.7.

[0262] The UE may discard the radio link failure information or handover failure information, i.e., release the UE variable VarRLF -Report, 48 hours after the radio link failure / handover failure is detected. NOTE 2: In this clause, the term 'handover failure' has been used to refer to 'reconfiguration with sync failure'.

[0263] *** End exemplary text for 3GPP TS 38.331 ***

[0264] In other embodiments, the UE only includes lastHO-Type field set to Itm and the previousPCellld and timeConnFailure fields. If lastHO-Type is set to Itm, the previousPCelUD and timeConnFailure fields represent the previous LTM target cell and the time elapsed since execution of LTM cell switch to that cell, respectively. On the other hand, if lastHO-Type is set to a different value or not set at all, the previousPCelUD field represents the previous source cell that triggered a L3 mobility procedure by sending the UE a reconfigurationWithSync, and the timeConnFailure field represents time elapsed since execution of the L3 mobility (i.e., the reconfiguration WithSync) .

[0265] Various features of the embodiments described above correspond to various operations illustrated in Figures 6-7, which show exemplary methods (e.g., procedures) for a UE and a RAN node, respectively. In other words, various features of the operations described below correspond to various embodiments described above. Furthermore, the exemplary methods shown in Figures 6-7 can be used cooperatively to provide various benefits, advantages, and / or solutions to problems described herein. Although Figures 6-7 show specific blocks in particular orders, the operations of the exemplary methods can be performed in different orders than shown and can be combined and / or divided into blocks having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

[0266] In particular, Figure 6 shows an exemplary method (e.g., procedure) for a UE configured to operate in a radio access network (RAN), according to various embodiments of the present disclosure. The exemplary method can be performed by a UE (e.g., wireless device) such as described elsewhere herein.

[0267] The exemplary method includes the operations of block 610, where the UE receives from the RAN one or more configurations associated with respective one or more layer- 1 (L2) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells. The exemplary method also includes the operations of block 650, where the UE subsequently detects a radio-related failure while operating in the RAN. The exemplary method also includes the operations of block 660, where in response to detecting the radio-related failure, the UE logs in a failure report information about the radio-related failure. The logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. The exemplary also includes the operations of block 690, where the UE sends to a RAN node a message that includes the failure report.

[0268] In some embodiments, the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report. In some embodiments, the exemplary method also includes the following operations, labelled with corresponding block numbers:

[0269] • (620) storing the received one or more LTM candidate cell configurations;

[0270] • (630) receiving from the RAN a command to execute the mobility procedure from a source cell to a target cell; and

[0271] • (640) executing the mobility procedure in accordance with the command,

[0272] The radio-related failure is detected during execution of the mobility procedure or in the target cell after successful completion of the mobility procedure.

[0273] In some of these embodiments, the mobility procedure is a layer-3 (L3) mobility procedure. In other of these embodiments, the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells. In some of these embodiments, the RAN node serves a further cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0274] In some of these embodiments, the logged information includes one or more of the following:

[0275] • a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure (e.g., lastHO-Type field discussed above);

[0276] • an identity of the source cell in which the command was received (e.g., previousLTMCell field discussed above);

[0277] • an identity of the UE’s last serving primary cell (PCell);

[0278] • a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure (e.g., timeConnFailure field discussed above);

[0279] • a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure (e.g., targetLTM-Configured field discussed above);

[0280] • a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure (e.g., timeSinceLTMConfiguration field discussed above);

[0281] • a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and • a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0282] In some variants of these embodiments, when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the logged information also includes one or more of the following:

[0283] • a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command (e.g., LTMTrigger field discussed above);

[0284] • an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE;

[0285] • an eighth indication of a cell type for the first LTM candidate cell (e.g., previousCellType field discussed above);

[0286] • a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch (e.g., timeSinceLTMConfiguration field discussed above);

[0287] • a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch;

[0288] • an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure;

[0289] In some further variants, the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell. For example, when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0290] In some of these embodiments, the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch. In some variants of these embodiments, the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure;. Also, the second information includes the following: an identity of the UE’ s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0291] In some embodiments, the exemplary method also includes the operations of blocks 670- 680, where the UE sends to the RAN node an indication that the UE has generated the failure report and receives from the RAN node a request for the failure report. The message is sent to the RAN node in block 690 in response to the request received in block 680.

[0292] In addition, Figure 7 shows an exemplary method (e.g., procedure) for a RAN node configured to serve UEs via a source cell, according to various embodiments of the present disclosure. The exemplary method can be performed by a RAN node (e.g., base station, eNB, gNB, ng-eNB, etc.) such as described elsewhere herein.

[0293] The exemplary method includes the operations of block 710, where the RAN node sends to a UE one or more configurations associated with respective LTM candidate cells. The exemplary method also includes the operations of block 750, where the RAN node receives a message including a failure report about a radio-related failure detected by the UE. The failure report includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations. The exemplary method also includes the operations of block 760, where based on the failure report, the RAN node performs one or more adjustments to the source cell.

[0294] In some embodiments, the radio-related failure is an RLF and the failure report is an RLF report. In some embodiments, the exemplary method also includes the operations of block 720, where the RAN node sends to the UE a command to execute the mobility procedure from the source cell to a target cell. The radio-related failure occurred during UE execution of the mobility procedure or in the target cell after successful UE completion of the mobility procedure.

[0295] In some of these embodiments, the mobility procedure is an L3 mobility procedure. In some variants of these embodiments, the command is sent by a centralized unit (CU) of the RAN node.

[0296] In other of these embodiments, the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells. In some variants of these embodiments, the command is sent by a distributed unit (DU) of the RAN node.

[0297] In some of these embodiments, the message is received in block 750 from a second RAN node that serves a cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0298] In some of these embodiments, the failure report includes one or more of the following:

[0299] • a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure (e.g., lastHO-Type field discussed above);

[0300] • an identity of the source cell in which the command was received (e.g., previousLTMCell field discussed above); • an identity of the UE’s last serving primary cell (PCell);

[0301] • a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure (e.g., timeConnFailure field discussed above);

[0302] • a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure (e.g., targetLTM-Configured field discussed above);

[0303] • a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure (e.g., timeSinceLTMConfiguration field discussed above);

[0304] • a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and

[0305] • a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0306] In some variants of these embodiments, performing one or more adjustments to the source cell in block 760 includes the following operations, labelled with corresponding sub-block numbers:

[0307] • (761) when the first indication indicates that the mobility procedure was an LTM cell switch, adjusting by a distributed unit (DU) of the RAN node one or more parameters that affect LTM cell switches from the source cell served by the DU; and

[0308] • (762) when the first indication indicates that the mobility procedure was an L3 mobility procedure, adjusting by a centralized unit (CU) of the RAN node one or more parameters that affect L3 mobility procedures from the source cell served by the CU.

[0309] In some variants of these embodiments, when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the failure report also includes one or more of the following:

[0310] • a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command (e.g., LTMTrigger field discussed above);

[0311] • an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE;

[0312] • an eighth indication of a cell type for the first LTM candidate cell (e.g., previousCellType field discussed above); • a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch (e.g., timeSinceLTMConfiguration field discussed above);

[0313] • a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and

[0314] • an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

[0315] In some further variants, performing one or more adjustments to the source cell in block 760 includes the operations of sub-block 763, where based on one or more of the fourth, ninth, tenth, and eleventh indications, the RAN node adjusts a timing of when UEs served by the source cell are provided LTM candidate cell configurations for at least the first LTM candidate cell.

[0316] In some further variants, the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a PCell, a PSCell, an SCell, or a non-serving cell. For example, when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0317] In some of these embodiments, the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch. In some variants of these embodiments, the first information includes the following: an identity of the UE’s last serving PCell prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure;. Also, the second information includes the following: an identity of the UE’ s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0318] In some embodiments, the exemplary method also includes the operations of blocks 730- 740, where the RAN node receives from the UE an indication that the UE has generated the failure report and sends to the UE a request for the failure report. The message is received from the UE in block 750 in response to the request sent in block 740.

[0319] 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. Figure 8 shows an example of a communication system 800 in accordance with some embodiments. In this example, communication system 800 includes a telecommunication network 802 that includes an 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 3 GPP access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor.

[0320] Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, telecommunication network 802 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in telecommunication network 802 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in telecommunication network 802, including one or more network nodes 810 and / or core network nodes 808.

[0321] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. 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.

[0322] 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.

[0323] 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.

[0324] 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).

[0325] 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. 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.

[0326] 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.

[0327] 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).

[0328] 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 if one or more of the UEs are low energy loT devices.

[0329] 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.

[0330] 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, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by 3 GPP, including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0331] 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).

[0332] UE 900 includes processing circuitry 902 that is operatively coupled via a bus 904 to an input / output interface 906, a power source 908, a memory 910, a communication interface 912, and / or any other component, or any combination thereof. 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.

[0333] 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).

[0334] 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.

[0335] 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 of 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.

[0336] 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 read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, 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.

[0337] 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 (eUICC), 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.

[0338] 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 an 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 a transmitter 918 and / or a 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., antenna 922) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0339] 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), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0340] 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 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0341] 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.

[0342] 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.

[0343] 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 3 GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0344] 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.

[0345] Figure 10 shows a network node 1000 in accordance with some embodiments. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (e.g., radio base stations, Node Bs, eNBs, gNBs), and 0-RAN nodes or components of an 0-RAN node (e g., 0-RU, 0-DU, O-CU).

[0346] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an 0-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0347] 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).

[0348] 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.

[0349] 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.

[0350] 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.

[0351] 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 (collected denoted computer program 1004a, which may be in the form of a computer program product) 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.

[0352] 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 frontend 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 an 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 front-end 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 baseband processing circuitry 1014, which is part of a digital unit (not shown).

[0353] 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.

[0354] 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.

[0355] 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.

[0356] 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.

[0357] 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. As used 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.

[0358] 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.

[0359] 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.

[0360] 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. In some embodiments, the virtualization environment 1200 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0361] 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 1200 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0362] Hardware 1204 includes processing circuitry, memory that stores software and / or instructions (collected denoted computer program 1204a, which may be in the form of a computer program product) 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 and 1208b (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. Virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to the VMs 1208.

[0363] 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 be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0364] 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 VM 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 the hardware 1204 and corresponds to the application 1202.

[0365] 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 function 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 a control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0366] 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.

[0367] 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.

[0368] 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. 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.

[0369] OTT connection 1350 may extend via a connection 1360 between host 1302 and network node 1304 and via a 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.

[0370] 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.

[0371] 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.

[0372] 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. For example, based on content of a failure report by a UE, a RAN node can determine whether the UE was configured with LTM candidate cell configuration(s) at the time of a radiorelated failure and if so, whether an LTM cell switch led to the radio-related failure. Moreover, based on an indication of whether the radio-related failure was associated with an LTM cell switch or an L3 mobility procedure, the RAN node can determine whether to send the report to a source DU (e.g., for LTM adjustment / optimization) or to a source CU / CU-CP (e.g., for L3 mobility adjustment / optimization). Furthermore, based on an indication of how long ago a UE had received its stored LTM candidate cell configuration(s), embodiments can enable the RAN to configure UEs more closely in time to when LTM candidate cell configurations are needed. At a high level, embodiments may improve UE mobility in RANs. When RANs improved in this manner are used to delivering OTT services to end users, they increase the value of the OTT services to the end users and to the service providers.

[0373] 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 non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0374] 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.

[0375] Figure 14 is a signaling diagram illustrating an example implementation of the methods of Figure 6 and Figure 7.

[0376] The network elements involved in the signaling diagram of Figure 14 are the UE 1410, which is configured to perform the method of Figure 6, and the network node 1420 which is configured to perform the method of Figure 7.

[0377] The UE 1410 receives one or more configurations 1430 from the network node 1420. The one or more configurations 1430 may correspond to the one or more configurations of the step 610 of the method of Figure 6, or may correspond to the one or more configurations of the step 710 of the method of Figure 7.

[0378] In an embodiment, the UE 1410 receives a command 1440. The command 1440 may correspond to the command 630 of the method of Figure 6, or may correspond to the command 720 of the method of Figure 7.

[0379] In an embodiment, the UE 1410 sends an indication 1450. The indication 1450 may correspond to the indication 670 of the method of Figure 6, or may correspond to the indication 730 of the method of Figure 7.

[0380] In an embodiment, the UE 1410 receives a request 1460. The request 1460 may correspond to the request 680 of the method of Figure 6, or may correspond to the request 740 of the method of Figure 7.

[0381] The UE 1410 sends a message 1470. The message 1470 may correspond to the message 690 of the method of Figure 6, or may correspond to the message 750 of the method of Figure 7. 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] 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.

[0386] 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.

[0387] Embodiments of the techniques and apparatus described herein also include, but are not limited to, the following enumerated examples:

[0388] Al . A method for a user equipment (UE) configured to operate in a radio access network (RAN), the method comprising: receiving from the RAN one or more configurations associated with respective one or more layer- 1 (L2) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells; subsequently detecting a radio-related failure while operating in the RAN; in response to detecting the radio-related failure, logging in a failure report information about the radio-related failure, wherein the logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations; and sending to a RAN node a message that includes the failure report.

[0389] A2. The method of embodiment Al, wherein the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

[0390] A3. The method of any of embodiments A1-A2, further comprising: storing the received one or more LTM candidate cell configurations; receiving from the RAN a command to execute the mobility procedure from a source cell to a target cell; and executing the mobility procedure in accordance with the command, wherein the radio-related failure is detected during execution of the mobility procedure or in the target cell after successful completion of the mobility procedure.

[0391] A4. The method of embodiment A3, wherein one of the following applies: the mobility procedure is a layer-3 (L3) mobility procedure; or the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells.

[0392] A5. The method of any of embodiments A3-A4, wherein the RAN node serves a further cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0393] A6. The method of any of embodiments A3-A5, wherein the logged information includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure; a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0394] A7. The method of embodiment A6, wherein when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the logged information also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

[0395] A8. The method of embodiment A7, wherein the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

[0396] A9. The method of embodiment A8, wherein when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0397] A10. The method of any of embodiments A3-A9, wherein the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

[0398] Al 1. The method of embodiment A10, wherein: the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0399] A12. The method of any of embodiments Al-Al 1, further comprising: sending to the RAN node an indication that the UE has generated the failure report; and receiving from the RAN node a request for the failure report, wherein the message is sent to the RAN node in response to the request.

[0400] Bl. A method for a radio access network (RAN) node configured serve user equipment (UEs) via a source cell, the method comprising: sending to a UE one or more configurations associated with respective one or more layer-1 (L2) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells; receiving a message including a failure report about a radio-related failure detected by the UE, wherein the failure report includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations; and based on the failure report, performing one or more adjustments to the source cell.

[0401] B2. The method of embodiment Bl, wherein the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

[0402] B3. The method of any of embodiments B1-B2, further comprising sending to the UE a command to execute the mobility procedure from the source cell to a target cell, wherein the radio-related failure occurred during UE execution of the mobility procedure or in the target cell after successful UE completion of the mobility procedure.

[0403] B4. The method of embodiment B3, wherein one of the following applies: the mobility procedure is a layer-3 (L3) mobility procedure; or the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells.

[0404] B5. The method of embodiment B4, wherein when the mobility procedure is an L3 mobility procedure, the command is sent by a centralized unit (CU) of the RAN node, and when the mobility procedure is an LTM cell switch, the command is sent by a distributed unit (DU) of the RAN node. B6. The method of any of embodiments B3-B5, wherein the message is received from a second RAN node that serves a cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

[0405] B7. The method of any of embodiments B3-B6, wherein the failure report includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure; a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

[0406] B8. The method of embodiment B7, wherein performing one or more adjustments to the source cell comprises: when the first indication indicates that the mobility procedure was an LTM cell switch, adjusting by a distributed unit (DU) of the RAN node one or more parameters that affect LTM cell switches from the source cell served by the DU; and when the first indication indicates that the mobility procedure was an L3 mobility procedure, adjusting by a centralized unit (CU) of the RAN node one or more parameters that affect L3 mobility procedures from the source cell served by the CU.

[0407] B9. The method of any of embodiments B7-B8, wherein when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the failure report also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

[0408] BIO. The method of embodiment B9, wherein performing one or more adjustments to the source cell comprises, based on one or more of the fourth, ninth, tenth, and eleventh indications, adjusting a timing of when UEs served by the source cell are provided LTM candidate cell configurations for at least the first LTM candidate cell.

[0409] Bl 1. The method of any of embodiments B9-B10, wherein the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

[0410] Bl 2. The method of embodiment Bl 1, wherein when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

[0411] B13. The method of any of embodiments B3-B12, wherein the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

[0412] B14. The method of embodiment Bl 3, wherein: the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

[0413] B15. The method of any of embodiments B1-B14, further comprising: receiving from the UE an indication that the UE has generated the failure report; and sending to the UE a request for the failure report, wherein the message is received from the LIE in response to the request.

[0414] Cl . A user equipment (UE) configured to operate in a radio access network (RAN), the UE comprising: communication interface circuitry configured to communicate with at least one RAN node; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments A1-A12.

[0415] C2. A user equipment (UE) configured to operate in a radio access network (RAN), the UE being further arranged to perform operations corresponding to the methods of any of embodiments A1-A12.

[0416] C3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radio access network (RAN), configure the UE to perform operations corresponding to the methods of any of embodiments A1-A12.

[0417] C4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radio access network (RAN), configure the UE to perform operations corresponding to the methods of any of embodiments A1-A12. DI . A radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the RAN node comprising: communication interface circuitry configured to communicate with UEs via the source cell; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments B 1 -B 15.

[0418] D2. A radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the RAN node being further arranged to perform operations corresponding to the methods of any of embodiments B1-B15.

[0419] D3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of embodiments B1-B15.

[0420] D4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of embodiments B1-B15.

Claims

CLAIMS1. A method for a user equipment (UE) configured to operate in a radio access network (RAN), the method comprising: receiving from the RAN one or more configurations associated with respective one or more layer- 1 (LI) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells; subsequently detecting a radio-related failure while operating in the RAN; in response to detecting the radio-related failure, logging in a failure report information about the radio-related failure, wherein the logged information includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations; and sending to a RAN node a message that includes the failure report.

2. The method of claim 1, wherein the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

3. The method of any of claims 1-2, further comprising: storing the received one or more LTM candidate cell configurations; receiving from the RAN a command to execute the mobility procedure from a source cell to a target cell; and executing the mobility procedure in accordance with the command, wherein the radio-related failure is detected during execution of the mobility procedure or in the target cell after successful completion of the mobility procedure.

4. The method of any of claim 3, wherein the logged information includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure;a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

5. The method of claim 4, wherein when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the logged information also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

6. The method of claim 5, wherein the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

7. The method of claim 6, wherein when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

8. The method of any of claims 3-7, wherein the information about a mobility procedureexecuted by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

9. The method of claim 8, wherein: the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

10. The method of any of claims 1-9, further comprising: sending to the RAN node an indication that the UE has generated the failure report; and receiving from the RAN node a request for the failure report, wherein the message is sent to the RAN node in response to the request.

11. A method for a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the method comprising: sending to a UE one or more configurations associated with respective one or more layer-1 (LI) or layer-2 (L2) triggered inter-cell mobility (LTM) candidate cells; receiving a message including a failure report about a radio-related failure detected by the UE, wherein the failure report includes one or more of the following: information about a mobility procedure executed by the UE, and information related to at least one of the LTM candidate cell configurations; and based on the failure report, performing one or more adjustments to the source cell.

12. The method of claim 11, wherein the radio-related failure is a radio link failure (RLF) and the failure report is an RLF report.

13. The method of any of claims 11-12, further comprising sending to the UE a command to execute the mobility procedure from the source cell to a target cell, wherein the radio-relatedfailure occurred during UE execution of the mobility procedure or in the target cell after successful UE completion of the mobility procedure.

14. The method of any of claim 13, wherein the message is received from a second RAN node that serves a cell in which the UE reestablished its connection to the RAN after successful completion of the mobility procedure to the target cell and the radio-related failure in the target cell.

15. The method of any of claims 13-14, wherein the failure report includes one or more of the following: a first indication of whether the mobility procedure was an LTM cell switch or an L3 mobility procedure; an identity of the source cell in which the command was received; an identity of the UE’s last serving primary cell (PCell); a second indication of time elapsed between the UE initiating execution of the mobility procedure and detecting the radio-related failure; a third indication that the UE was configured with one or more LTM candidate cell configurations at the time of the radio-related failure; a fourth indication of time elapsed between storing the last received LTM candidate cell configuration and detecting the radio-related failure; a fifth indication of whether the UE’s most recent LTM cell switch was initiated based on one or more conditions associated with the LTM candidate cell configuration used for the most recent LTM cell switch; and a sixth indication of whether the UE’s most recent LTM cell switch was performed autonomously by the UE in response to another failed LTM cell switch.

16. The method of claim 15, wherein performing one or more adjustments to the source cell comprises: when the first indication indicates that the mobility procedure was an LTM cell switch, adjusting by a distributed unit (DU) of the RAN node one or more parameters that affect LTM cell switches from the source cell served by the DU; and when the first indication indicates that the mobility procedure was an L3 mobility procedure, adjusting by a centralized unit (CU) of the RAN node one or more parameters that affect L3 mobility procedures from the source cell served by the CU.

17. The method of any of claim 15-16, wherein when the mobility procedure is an LTM cell switch and the target cell is a first one of the LTM candidate cells, the failure report also includes one or more of the following: a seventh indication of whether the command to execute the LTM cell switch was a LI command or a L2 command; an identity of a cell in which the configuration for the first LTM candidate cell was received by the UE; an eighth indication of a cell type for the first LTM candidate cell; a ninth indication of time elapsed between the UE storing the last received LTM candidate cell configuration and initiating execution of the LTM cell switch; a tenth indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and initiating execution of the LTM cell switch; and an eleventh indication of time elapsed between the UE receiving the configuration for the first LTM candidate cell and detecting the radio-related failure.

18. The method of claim 17, wherein performing one or more adjustments to the source cell comprises, based on one or more of the fourth, ninth, tenth, and eleventh indications, adjusting a timing of when UEs served by the source cell are provided LTM candidate cell configurations for at least the first LTM candidate cell.

19. The method of any of claims 17-18, wherein the eighth indication of the cell type indicates that the first LTM candidate cell is one of the following: a primary cell (PCell), a primary secondary cell group cell (PSCell), a secondary cell (SCell), or a non-serving cell.

20. The method of claims 19, wherein when the eighth indication of the cell type indicates that the first LTM candidate cell is an SCell, the eighth indication of cell type further indicates whether the first LTM candidate cell is associated with the UE’s master cell group (MCG) or the UE’s SCG.

21. The method of any of claims 13-20, wherein the information about a mobility procedure executed by the UE includes at least one of the following: first information associated with a most recent L3 mobility procedure, and second information associated with a most recent LTM cell switch.

22. The method of claim 21, wherein: the first information includes the following: an identity of the UE’s last serving primary cell (PCell) prior to the most recent L3 mobility procedure, and an indication of time elapsed between initiating execution of the most recent L3 mobility procedure and detecting the radio-related failure; and the second information includes the following: an identity of the UE’s last serving PCell prior to the most recent LTM cell switch, and an indication of time elapsed between initiating execution of the most recent LTM cell switch and detecting the radio-related failure.

23. The method of any of claims 11-22, further comprising: receiving from the UE an indication that the UE has generated the failure report; and sending to the UE a request for the failure report, wherein the message is received from the UE in response to the request.

24. A user equipment (UE) configured to operate in a radio access network (RAN), the UE comprising: communication interface circuitry configured to communicate with at least one RAN node; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of claims 1-10.

25. A user equipment (UE) configured to operate in a radio access network (RAN), the UE being further arranged to perform operations corresponding to the methods of any of claims 1- 10.

26. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radio access network (RAN), configure the UE to perform operations corresponding to the methods of any of claims 1-10.

27. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a user equipment (UE) configured to operate in a radioaccess network (RAN), configure the UE to perform operations corresponding to the methods of any of claims 1-10.

28. A radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the RAN node comprising: communication interface circuitry configured to communicate with UEs via the source cell; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of claims 11-23.

29. A radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, the RAN node being further arranged to perform operations corresponding to the methods of any of claims 11-23.

30. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of claims 11-23.

31. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to serve user equipment (UEs) via a source cell, configure the RAN node to perform operations corresponding to the methods of any of claims 11-23.

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