Signaling at detection of PING-PONG cell switching in long term evolution communication networks

Abstract

Methods performed by a central unit, CU, in a communications network include logging information about L1 / L2 triggered mobility, LTM,-related mobility events in an LTM UE mobility history residing in memory while the UE remains connected to the CU. The methods receive LTM-related information for a LTM cell switch relating to the UE and a distributed unit, DU. The methods detect ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history. Based on the detecting of the ping-pong LTM cell switches, the methods generate an information element (IE) indicating that an LTM ping-pong event was detected for the UE, and send other LTM-related information containing the IE to the DU and / or to another DU. Related methods by a DU and related CUs and DUs are disclosed.

Description

SIGNALING AT DETECTION OF PING-PONG CELL SWITCHING IN LONG TERM EVOLUTION COMMUNICATION NETWORKSTECHNICAL FIELD

[0001] The present disclosure relates generally to 3GPP specified mobile communications networks, in particular Mobility Robustness Optimization (MRO), part of Self Organizing Networks (SON).BACKGROUND

[0002] In release 8 of the 3GPP standard, the Evolved Packet System (EPS) was specified. EPS is based on the Long-Term Evolution (LTE) radio network and the Evolved Packet Core (EPC). It was originally intended to provide voice and mobile broadband (MBB) services but has continuously evolved to broaden its functionality. Since Release 13 NB-IoT and LTE-M are part of the LTE specifications and provide connectivity to massive machine type communications (mMTC) services.

[0003] In 3GPP release 15, the first release of the 5G system (5GS) was specified. This is anew generation radio access technology intended to serve use cases such as enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC) and mMTC services. 5G includes the New Radio (NR) access stratum interface and the 5G Core Network (5GC). The NR physical and higher layers are reusing parts of the LTE specification, and additional components are introduced when motivated by the new use cases. One such component is the introduction of a sophisticated framework for beam forming and beam management to extend the support of the 3GPP technologies to a frequency range going beyond 6 GHz.

[0004] In the work on release 15 of the 3GPP standard, 3GPP also started the work to prepare NR for operation in a Non-Terrestrial Network (NTN). The work was performed within the Study Item “NR to support Non-Terrestrial Networks” and resulted in 3GPP TR 38.811 [1], In 3GPP release 16, the work to prepare NR for operation in a Non-Terrestrial Network continued with the Study Item “Solutions for NR to support Non-Terrestrial Network” which resulted in 3GPP TR 38.821 [2],

[0005] The Release 16 study item resulted in a Work Item being agreed for NR in Release 17, “Solutions for NR to support non-terrestrial networks (NTN)”, which is described in the Work Item Description RP-193234.

[0006] Operations related to the concept of mobility in mobile networks are described. Mobility is the mechanisms where a UE can switch its attachment to a mobile network. Typical mobility is between cells and between beams within cells.

[0007] In 5G mobile networks, one base station (gNB) is logically split between one Centralized Unit (CU) and one or more Distributed Units (DU.) Each DU is responsible for one or more cells. Each cell can consist of one or more beams. The CU is responsible for the overall mobility, especially mobility between cells handled by different gNBs, but also between cells handled by the CU’s DUs. Mobility between cells controlled by one CU but between different DUs is called Inter-DU mobility. Mobility between cells controlled by one DU is called Intra-DU mobility.

[0008] Traditional mobility is handled by layer 3 handovers, where CUs are in charge of the mobility. Since 3GPP Rell8, a new mechanism has been specified for mobility. This mechanism, Layerl / Layer 2 triggered mobility (LTM) gives the DU more responsibility for the mobility, using a mechanism called LTM cell switch. See 3GPP TS 38.300 version 18.5.0, clause 9.2.3.5.

[0009] Optimization is a key feature of an operator’s mobile network. Optimization is the ability of network nodes (e.g. CUs and DUs) to improve performance of the network by gathering data of the current performance of the network, and perform changes to the configuration of the network nodes and it currently attached UEs.

[0010] In mobility, there is an unwanted condition called ping-pong. Ping-pong occurs when a UE is quickly moved back and forth between cells in an unwanted manner.

[0011] Ping-pong definition: Ping-pong is defined in the Inter-system case for NR, see 3GPP TS 38.300 version 18.5.0, clause 15.5.2.4. For the purpose of this invention, we define ping-pong LTM as the LTM cell switch of a UE from cell A to cell B, and that the UE returns using an LTM cell switch to cell A again, all within a limited time, typically within a few seconds. Note that this definition finds ping-pong even if three cells are involved, i.e. A -> B -> C -> A.

[0012] The information that a node (CU or DU) has about a connected UE is called the UE context. The UE context can be different between different nodes, as different nodes need to keep different data about the UE’s connection. The UE context is created when the UEconnects to the network node (CU and DU), and is deleted when the UE leaves the cells controlled by the CU and DU. The CU and DU may keep the UE context for some time after the UE leaves. The CU and DU may keep the UE context for different amounts of time. Typically, a DU deletes the UE context before the CU does, as the DU has less memory and processing capabilities than the CU.

[0013] This invention is related to the procedure for the LTM cell switch, as specified in 3GPP TS 38.401 version 18.5.0, clause 8.2.1.5, which describes Inter-DU LTM cell switches. Figure 8.2.1.5-1 from that specification is illustrated in the combined Figures 1 A and IB of the present disclosure.

[0014] In Figures 1A and IB, message 19 (DU-CU CELL SWITCH NOTIFICATION) is used, and message 20 (CU-DU CELL SWITCH NOTIFICATION) is updated.

[0015] Messages 19 and 20 are defined in 3GPP TS 38.473 version 18.5.0, clauses 9.2.2.15 and 9.2.2.16, respectively.

[0016] The operations illustrated in combined Figures 1A and IB are now described:1. The UE sends a MeasurementReport message (L3 measurement result) to the source gNB-DU containing measurements of neighbouring cells. The source gNB-DU sends an UL RRC MESSAGE TRANSFER message conveying the received MeasurementReport message to the gNB-CU.2. The gNB-CU determines to initiate LTM configuration.3. The gNB-CU sends a UE CONTEXT SETUP REQUEST message to the candidate gNB-DU(s) for each candidate cell, containing one candidate cell ID and the CSI resource configuration for subsequent LTM. The gNB-CU may provide the LTM configuration ID mapping list to the candidate gNB-DU(s). The gNB-CU may request PRACH resources from the candidate gNB-DU(s). The gNB-CU may request the candidate gNB-DU(s) to provide the lower layer configuration for the purpose of generating the reference configuration or provide the lower layer part of the reference configuration to the candidate gNB-DU(s).4. If the candidate gNB-DU accepts the request of LTM configuration, it responds with a UE CONTEXT SETUP RESPONSE message including the generated lower layer RRC configurations for the accepted target candidate cell.NOTE 1 : The CU-initiated UE Context Modification procedure may be initiated for preparing candidate cells in the source gNB-DU as specified in step 3 and 4 in 8.2.1.4 Intra-gNB-DU LTM.5. The gNB-CU sends a UE CONTEXT MODIFICATION REQUEST message to the source gNB-DU including the information related to early sync and the LTM configuration ID mapping list for the accepted target candidate cell(s). The gNB-CU may send the updated CSI resource configuration to the source gNB-DU. The gNB-CU may inform the source gNB-DU about intra-DU L2 reset configuration.6. The source gNB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message which includes an updated lower layer configuration, e.g., containing the updated CSI report configuration of the source cell.7. The gNB-CU may send a UE CONTEXT MODIFICATION REQUEST message for each candidate cell accepted in the candidate gNB-DU(s), containing the information for subsequent LTM or for updating the configurations of candidate cells. The gNB-CU may also provide the lower layer part of the reference configuration to the candidate gNB-DU(s). The gNB-CU may inform the candidate gNB-DU(s) about intra-DU L2 reset configuration.8. The candidate gNB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message including the updated lower layer configuration, e.g., containing the updated CSI report configuration of the requested candidate cell.NOTE 2: Step 7 may also be triggered after step 19, or after step 22 by implementation for subsequent LTM.9. The gNB-CU sends a DL RRC MESSAGE TRANSFER message to the source gNB-DU, which includes the generated RRCReconfiguration message with the LTM configuration.10. The source gNB-DU forwards the received RRCReconfiguration message to the UE.11. The UE responds to the source gNB-DU with an RRCReconfigurationComplete message.12. The source gNB-DU forwards the RRCReconfigurationComplete message to the gNB-CU via an UL RRC MESSAGE TRANSFER message.13. Early TA acquisition to the candidate cell(s) may be performed as specified in TS 38.300 [2],14. The candidate gNB-DU sends a DU-CU TA INFORMATION TRANSFER message to the gNB-CU, which includes the TA values, and the associated PRACH resource information.15. The gNB-CU forwards the TA value, and the associated PRACH resource information to the source gNB-DU in the CU-DU TA INFORMATION TRANSFER message.16. The UE sends the LI measurement result to the source gNB-DU.17. The source gNB-DU decides to execute LTM to a target cell.18. The source gNB-DU sends the Cell Switch Command to the UE.19. The source gNB-DU sends the DU-CU CELL SWITCH NOTIFICATION message to the gNB-CU to indicate the initiation of the Cell Switch Command to the UE, including the target cell ID and the TCI state ID(s). The TA value(s) related information applicable for subsequent LTM may also be included.20. The gNB-CU forwards in the CU-DU CELL SWITCH NOTIFICATION message to the target gNB-DU the target cell ID, the TCI state ID(s), and the TA value(s) related information received in step 19.21. The target gNB-DU detects the UE access as specified in TS 38.300 [2], 22. The target gNB-DU sends the ACCESS SUCCESS message to the gNB-CU with the target cell ID.23. The UE sends an RRCReconfigurationComplete message to the target gNB-DU.24. The target gNB-DU forwards the RRCReconfigurationComplete message to the gNB-CU via an UL RRC MESSAGE TRANSFER message.25. The gNB-CU may send the UE CONTEXT RELEASE COMMAND message to the source gNB-DU to release the resources of prepared cells.26. The source gNB-DU responds with a UE CONTEXT RELEASE COMPLETE message.

[0017] L1 / L2 Triggered Mobility (LTM) will now be described.

[0018] An overall description of L1 / L2 Triggered Mobility (LTM) is provided in section 9.2.3.5 of 3GPP TS 38.300 version 18.5.0. That section is copied and included below:

[0019] Section 9.2.3.5.1 General is now described.

[0020] LTM is a procedure in which a gNB receives LI or L3 measurement report(s) from a UE, and on their basis the gNB may change UE serving cell by a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency as described in Annex G.

[0021] When configured by the network, it is possible to activate TCI states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered. All the activated TCI states except those received in the cell switch command are deactivated upon LTM cell switch execution.

[0022] When configured by the network, it is possible to initiate UL TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTA as the current serving cells or NTA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by PDCCH order as specified in clause 9.2.6 or realized through UE-based TA measurement as configured by RRC. In the former case, the gNB / gNB-DU to which the candidate cell belongs calculates the TA value and sends it to the gNB / gNB-DU to which the serving cell belongs via gNB-CU. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command, if it does not include any valid TA value. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0023] When two TAG IDs are configured for an LTM candidate cell, the gNB-DU to which the LTM candidate cell belongs assigns the same TAG ID pointer value for each TRP to be used by the UEs.

[0024] Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the valid TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no valid TA value is provided in the cell switch command, the UE applies the valid TA value by itself if available. The UE performs RACH-less LTM cell switch upon receiving the cell switch command whenever a valid TA value is available. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

[0025] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes performing arandom access procedure towards one or more candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

[0026] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UE shall not trigger random access procedure if it does not have a valid PUCCH resource for triggered SRs.

[0027] The following principles apply to LTM:Security keys are maintained upon an LTM cell switch;Subsequent LTM is supported.

[0028] LTM supports both intra-gNB-DU and inter-gNB-DU mobility within the same gNB-CU. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. The following scenarios are supported:PCell change in non-CA scenario and non-DC scenario;PCell and SCell(s) change in CA scenario;Dual connectivity scenario: including PCell and MCG SCell(s) change and intra- SN PSCell and SCG SCell(s) change without MN involvement. LTM for simultaneous PCell and PSCell change is not supported.

[0029] While the UE has stored LTM candidate configurations the UE can also execute any L3 handover except for DAPS handover. In the RRC message which the UE applies for any L3 handover (except DAPS), LTM candidate configurations can be added / modified / released by the target cell.

[0030] 9.2.3.5.2 C-Plane Handling is now described.

[0031] Cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0032] The overall procedure for LTM is shown in Figure 9.2.3.5.2-1 which is illustrated as Figure 2 of this disclosure. Subsequent LTM is done by repeating the early synchronization,LTM cell switch execution, and LTM cell switch completion steps without the need to release, reconfigure or add other LTM candidate configurations after each LTM cell switch completion. The general procedure over the air interface is applicable to SCG LTM. Further details of SCG LTM can be found in TS 37.340

[0021] ,

[0033] The procedure for LTM is now described with reference to Figure 2 of the present disclosure, as follows:1. The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates LTM preparation.2. The gNB transmits an RRCReconfiguration message to the UE including the LTM candidate configurations.3. The UE stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB.4a. The UE performs DL synchronization with the LTM candidate cell(s) before receiving the cell switch command. The UE may activate and deactivate TCI states of LTM candidate cell(s), as triggered by the gNB and defined in TS 38.133

[0013] , 4b. The UE may perform UL synchronization with LTM candidate cell(s) before receiving the cell switch command, by using UE-based TA measurement, if configured, and / or by transmitting a preamble towards the candidate cell, as triggered by the gNB. When UE-based TA measurement is configured, UE acquires the TA value(s) of the candidate cell(s) by measurement. UE performs early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command as specified in clause 9.2.6 and TS 38.133

[0013] , This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE does not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE does not maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity. 5. The UE performs LI measurements on the configured LTM candidate cell(s) and transmits LI measurement reports to the gNB. LI measurement should be performed as long as RRC reconfiguration (step 2) is applicable. The UE can also perform L3 measurement reporting to the gNB, including beam level measurement results on cell(s)which are configured as LTM candidate cell(s) according to the received network configuration.6. The gNB decides to execute cell switch to a target cell and transmits an LTM cell switch command MAC CE triggering cell switch by including a target configuration ID which indicates the index of the candidate configuration of the target cell, a beam indicated with a TCI state or beams indicated with DL and UL TCI states, and a timing advance command for the target cell, if available. The UE switches to the target cell and applies the candidate configuration indicated by the target configuration ID.7. The UE performs the random access procedure towards the target cell, if UE does not have valid TA of the target cell as specified in clause 5.18.35 of TS 38.321 [6] . 8. The UE completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the UE has performed a RA procedure in step 7 the UE considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data.

[0034] The steps 4-8 can be performed multiple times for subsequent LTM cell switch executions using the LTM candidate configuration(s) provided in step 2.

[0035] The procedure over the air interface described in Figure 9.2.3.5.2-1 is applicable to both intra-gNB-DU LTM and inter-gNB-DU LTM. The overall LTM procedures over Fl-C interface are captured in TS 38.401 [4],

[0036] Section 9.2.3.5.3 U-Plane Handling is now described.

[0037] After receiving an LTM cell switch command MAC CE, the UE performs MAC reset. Whether the UE performs RLC re-establishment and PDCP data recovery during cell switch is explicitly controlled by the network through RRC signalling.

[0038] Self-Organizing Networks (SON) are now described in the context of this disclosure. SON is a collection of functions for automatic configuration, optimization, and healing of networks. The aim of the framework is to perform routine maintenance and optimization where necessary without additional configuration. To enable this functionality, multiple reports are defined and collected from the UE. Some relevant ones are introduced below.

[0039] A Successful PSCell Addition / Change Report (SPR) is generated by a UE performing a PSCell addition or change if the conditions set by the network are fulfilled. Theseconditions are configured to trigger the UE to generate an SPR in cases where a PSCell addition or change is successful but close to failing.

[0040] If an RRC connected UE (i.e. a UE in RRC CONNECTED state) declares radio link failure it creates a Radio Link Failure report and network can fetch it from the UE. In a RLF report, UE includes necessary information and measurements for the network to analyze the radio condition and possibly physical location of the UE. Network thus can take appropriate action upon analyzing the RLF report. There are multiple scenarios where UE may declare radio link failure; details can be found in 3GPP TS 38.300 version 18.5.0 and 3GPP TS 38.331 version 18.5.0.

[0041] A UE operating in dual connectivity mode may encounter problems in the Secondary Cell Group (SCG) and declare failure on the SCG connectivity leg. If the connection to the Master Cell Group (MCG) connectivity leg is active, the UE does not declare radio link failure, instead it sends an SCGFailurelnformation RRC message to the MN. Upon receiving the message, the MN can take necessary actions to solve the problems.

[0042] A Successful Handover Report (SHR) is generated by a UE performing a PCell handover if the conditions set by the network are fulfilled. These conditions are configured to trigger the UE to generate an SHR in cases where a PCell handover is successful but close to failing.

[0043] The triggering conditions for the generation of the SHR can be configured by the source cell (before the HO execution), or by the target cell (in the HO command):• Elapsed T304 above configured T304 threshold (condition configured by the target cell)• Elapsed T310 above configured T310 threshold (condition configured by the source cell)• Elapsed T312 above configured T312 threshold (condition configured by the source cell)• RLF in source cell during DAPS HO (condition configured by the source cell)

[0044] In 3GPP release 19, the SHR will be extended with new fields / IEs to be used when the reported mobility procedure is an LTM procedure.

[0045] Adding SON support for LTM is in the scope of the work with release 19 of the 3GPP standard, it is generally regarded to belong to the part of SON referred to as Mobility Robustness Optimization (MRO). RAN3 and RAN2 have agreed on some information to be included in SON reports sent from the UE to the network, e.g. the RLF report and the SHR,wherein some of the information is chosen to be similar to what has been specified for those reports for handover and conditional handover. However, significant work remains until a comprehensive feedback framework is in place to properly support optimization of the LTM configuration.

[0046] There currently exist certain challenge(s).

[0047] A DU uses a set of parameters to determine whether it is suitable to trigger an LTM cell switch for a UE. Such parameters may e.g. be offset(s) and threshold(s) related to reported channel quality quantities, but may also comprise consideration of other aspects, such as the load in the cell. Such offset(s) and threshold(s) typically serve the dual purpose of ensuring that the LTM cell switch execution is performed when it is appropriate considering the current situation, and creating a hysteresis for LTM cell switches at a specific cell border (i.e. fast nonsignificant fluctuations of the channel qualities in the source and target cells should not trigger LTM cell switches back and forth between the same cells, i.e. so-called ping-pong LTM cell switches or ping-pong behavior). Hence, poor configuration of such offset(s) and threshold(s) may result in ping-pong LTM cell switches, which results in excessive use of signaling resources, waste of energy in the UE (e.g. draining the UE’s battery) reduced UE throughput (i.e. reduced experienced service quality) and inefficient use of transmission resources.

[0048] Ping-pong LTM cell switches between cells controlled by the same DU can (at least in principle) be detected by the DU and the DU can adjust their LTM cell switch execution trigger policies to avoid the ping-pong behavior, e.g. changing offset(s) and threshold(s) that control the hysteresis. However, when ping-pong LTM cell switches occur between cells controlled by different DUs (i.e. inter-DU ping-pong LTM) there is currently no way for the involved DUs to become aware of the ping-ponging and thus they cannot take any action to improve the situation. Furthermore, if a DU would perform adaptive adjustments of LTM cell switch triggering parameters when the ping-pong LTM cell switches occur between cells controlled by different DUs, uncoordinated offset / threshold adaptations in the two DUs may result in a new poor or even worse hysteresis configuration. Furthermore, uncoordinated adjustments of offsets and thresholds for LTM cell switch execution may result in biased UE distribution between the involved cells (i.e. an undesirable tendency to gather more cell edge UEs to one of the cells than to the other), e.g. if the adjustments are biased or one-sided.SUMMARY

[0049] Various embodiments of the present disclosure are directed to methods and operations by a CU and / or a DU to detect ping-pong L1 / L2 triggered mobility (LTM) cell switches.

[0050] In some embodiments, methods performed by a CU in a communications network include logging information about LTM-related mobility events in an LTM UE mobility history residing in memory while the UE remains connected to the CU. The methods receive LTM-related information for a LTM cell switch relating to the UE and a DU. The methods detect ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history. Based on the detecting of the ping-pong LTM cell switches, the methods generate an information element (IE) indicating that an LTM ping-pong event was detected for the UE, and send other LTM-related information containing the IE to the DU and / or to another DU.

[0051] In some other embodiments, methods performed by a DU in a communications network include receiving LTM-related information containing an IE indicating that a CU detected an LTM ping-pong event characterized by ping-pong LTM cell switches of a UE between at least two cells. The methods responsively adapt mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE.

[0052] In some other embodiments, a CU in a communications network includes processing circuitry configured to perform operations corresponding to one or more of the methods described herein by the CU.

[0053] In some other embodiments, a DU in a communications network includes processing circuitry configured to perform operations corresponding to one or more of the methods described herein by the DU.

[0054] Thus, in accordance with various embodiments disclosed herein, upon detection of ping-pong LTM switches (one-time or more times) which satisfies a defined rule, a CU can operate to inform one or both of the involved DUs and provide further instruction and information to ensure an optimal coordinated resolution of the problem, e.g. adaptation of parameters controlling LTM cell switch execution decision in order to increase the mobility hysteresis between the two involved cells. Various embodiments of the present disclosure may provide one or more of the following technical advantage(s). The CU communications provide the DUs involved in the ping-pong the operational ability to change their mobilityconfigurations for future LTM cell switches, in order to reduce the risk of future ping-pong cell switches. The operations also enable the CU or the DUs to stop the ongoing ping-pong mobility. Furthermore, the various embodiments enable coordination of adjustments of offsets and thresholds for LTM cell switch execution triggering in different DUs, so that a suitable (more optimal) hysteresis can be created to avoid ping-pong LTM cell switches and biases in UE distribution between cells controlled by different DUs.

[0055] Other methods, CUs, DUs, and corresponding computer program products according to embodiments of the present disclosure will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. Moreover, it is intended that all embodiments disclosed herein can be implemented separately or combined in any way and / or combination.BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Embodiments of the invention will be described in the following, reference being made to the appended drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice.

[0057] Figures 1A and IB illustrate a flowchart of communications between a UE and components of a communications network in accordance with some embodiments;

[0058] Figure 2 illustrates a flowchart of communications between a UE and gNB in accordance with some embodiments;

[0059] Figure 3 illustrates a flowchart of operations that can be performed by a CU in a communications network according to some embodiments;

[0060] Figure 4 illustrates a flowchart of operations that can be performed by a DU in a communications network according to some embodiments;

[0061] Figure 5 shows an example of a communication system in accordance with some embodiments;

[0062] Figure 6 is another example of a communication system according to some embodiments;

[0063] Figure 7 shows a wireless device, which may be configured to operate in communication system of Figure 5 or in communication system of Figure 6 in accordance with some embodiments;

[0064] Figure 8 shows a network node in accordance with some embodiments; and Figure 9 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized.DETAILED DESCRIPTION

[0065] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0066] Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges.

[0067] A CU can detect ping-pong LTM cell switches between two cells controlled by different ones of the DUs connected to the CU, e.g. by observing LTM cell switches and tracing whether an LTM cell switch is followed by an LTM cell switch in the other direction (i.e. back to the source cell of the preceding LTM cell switch) within a short time. If this happens often across the same cell border (i.e. between the same two cells), the CU may conclude that the offset(s) and / or threshold(s) the one or both of the UEs use for determining when to trigger LTM cell switching are suboptimal. The CU may get the input to this observation strategy from the F1AP messages DU-CU CELL SWITCH NOTIFICATION (sent from the source DU to the CU when an LTM cell switch has been triggered) and ACCESS SUCCESS (sent from the target DU to the CU when the UE has successfully accessed the target cell of an LTM cell switch (and similar also for other mobility procedures).

[0068] Based on these observations and detection of LTM cell switch ping-pong behavior, and taking various situational aspects known to the CU (e.g. known DU configurations, current cell load, current number of connected UEs in different cells) into account, the CU can inform one or both of the involved DUs of the detected LTM cell switch ping-pong behavior and / or instruct one or both of the involved DUs to perform certain actions to resolve / improve the situation without creating other problems (such as UE distribution bias) as a consequence of the actions.

[0069] A CU can also detect ping-pong LTM cell switches between two cells controlled by the same DU connected to the CU.

[0070] A DU can also detect ping-pong LTM cell switches between two cells of the DU and provide assistance information to the CU, to indicate the presence of ping-pong LTM cell switches.

[0071] A CU can further detect ping-pong Conditional LTM cell switches between cells controlled by different DUs under its control, or between cells controlled by the same DU under its control.

[0072] A DU can further detect ping-pong Conditional LTM cell switches between two cells of the DU and provide assistance information to the CU, to indicate the presence of ping-pong Conditional LTM cell switches.

[0073] Thus, in accordance with various operational embodiments disclosed herein, upon detection of ping-pong LTM switches (one-time or that this frequently happens) which satisfies a defined rule, a CU operates to inform one or both of the involved DUs and provide further instruction and information to ensure an optimal coordinated resolution of the problem, e.g. adaptation of parameters controlling LTM cell switch execution decision in order to increase the mobility hysteresis between the two involved cells.

[0074] These operations can include methods for detection of ping-pong LTM cell switches for intra-CU inter-DU LTM cell switches, intra-DU LTM cell switches and inter-CU LTM cell switches.

[0075] Various embodiments of the present disclosure may provide one or more of the following technical advantage(s).

[0076] The CU communications provide the DUs involved in the ping-pong the operational ability to change their mobility configurations for future LTM cell switches, in order to reduce the risk of future ping-pong cell switches. The operations also enable the CU or the DUs to stop the ongoing ping-pong mobility.

[0077] Furthermore, the various embodiments enable coordination of adjustments of offsets and thresholds for LTM cell switch execution triggering in different DUs, so that a suitable (more optimal) hysteresis can be created to avoid ping-pong LTM cell switches and biases in UE distribution between cells controlled by different DUs.

[0078] Before describing these embodiments in further detail, the following notes of terminology explanations and generalizations are relevant for understanding the described operations and methods in the context of this disclosure.

[0079] The term “network” is used herein to refer to a network node, which typically will be a gNB, but which may also be an eNB, or a base station or an access point in another type of network, or any other network node with the ability to directly or indirectly communicate with a UE. Refinements with finer granularity are also conceivable. For instance, a gNB may be an en-gNB, and if a split gNB architecture is applied (dividing the gNB into multiple separate entities or nodes), the term “node” may refer to a part of the gNB, such as a gNB-CU (often referred to as just CU), a gNB-DU (often referred to as just DU), a gNB-CU-CP or a gNB-CU-UP. Similarly, an eNB may be an ng-eNB, and if a split eNB architecture is applied(dividing the eNB into multiple separate entities or nodes), the term “network” (and the network node it implies) may refer to a part of the eNB, such as an eNB-CU, an eNB-DU, an eNB-CU-CP or an eNB-CU-UP. Furthermore, the term “network” (and the network node it implies) may also refer to an lAB-donor, lAB-donor-CU, lAB-donor-DU, lAB-donor-CU-CP, or an lAB-donor-CU-UP.

[0080] The terms “LTM candidate cell” and “LTM target cell” are used herein. The term “LTM candidate cell” refers to a cell which has been prepared to be the potential target of an LTM cell switch, wherein the preparation consists of configuration data that has been provided to the UE and which the UE should apply if / when executing the LTM cell switch towards the concerned LTM candidate cell as well as configuration data in the DU which serves and controls the LTM candidate cell. The term “LTM target cell” is used to refer to the LTM candidate cell for which execution of the LTM cell switch is triggered. Correspondingly, an “LTM candidate DU” refers to a DU that serves / controls one or more LTM candidate cell(s), and an “LTM target DU” refers to the DU that serves / controls the LTM target cell. In the context of this document, an LTM candidate cell may also simply be referred to as a “candidate cell” and an LTM target cell may be referred to as a “target cell”. Correspondingly, an LTM candidate DU may be referred to as a “candidate DU” and an LTM target DU may be referred to as a “target DU”. Furthermore, the source cell of an LTM cell switch (i.e. the cell in which the UE is connected when the LTM cell switch execution is triggered) may be referred to as the “LTM source cell” or, for simplicity, the “source cell”. Correspondingly, the DU controlling the LTM source cell may be referred to as the “LTM source DU” or, for simplicity, the “source DU”.

[0081] That a UE generates a SON report (e.g. generates an SHR) and that UE logs a SON report (e.g. logs an SHR) are herein considered to be the same type of action.

[0082] In this disclosure, NR is used as the radio access technology of reference. However, this is only an example taken for simplicity and it should not be limiting. The disclosed operations and methods apply to any radio access technology which supports a mobility mechanism that uses RACH-less access in the target cell of the mobility procedure, in particular (but not only) when the mobility mechanism uses early UL synchronization in the cell that will become the target cell to support RACH-less access in the target cell.

[0083] The terms information element (IE) and field are used more or less interchangeably herein. Also the term parameter is sometimes used to denote the same concept.

[0084] Parameters / IEs / fields used in ASN.1 code as well as in procedural text in the 3GPP RRC specification for 5G / NR, i.e. 3GPP TS 38.331 (of which the most recent official version at the time of writing is version 18.5.0), are often named with a suffix indicating the number of the release of the 3GPP standard the parameter / IE / field was introduced in (e.g. the suffix rl8” for a parameter / IE / field introduced in release 18 of the 3GPP standard). Parameters / IEs / fields following this naming convention are typically referred to both with and without the suffix, where the name including the suffix is used in the ASN.1 code (and thus defines the formal name from the ASN.l compiler’s perspective), while the name without the suffix is used in running text, e.g. in field descriptions and procedural text. In this disclosure, both name variants may occur for various parameters / IEs / fields.

[0085] When writing message names of a communication protocol, two equivalent principles are used in this disclosure. The writing principle “<protocol name> <message name> message”, for example “XnAP HANDOVER REQUEST message”, and the writing principle “<message name> <protocol name> message”, for example “HANDOVER REQUEST XnAP message” are equivalent, both referring to a message (i.e., “<message name>”) of a communication protocol (i.e., “<protocol name>”), e.g., the HANDOVER REQEUST message of the communication protocol XnAP. The same writing format equivalence applies to other communication protocols, such as NGAP, RRC and MAC.

[0086] This disclosure refers to a UE’s transmission timing error. It is noted that this is equivalent to the reception timing error in the node receiving the UE’s transmission, i.e. the amount of time by which the reception timing deviated from the ideal reception timing, i.e. the time at which the UE’s transmission should have been received if the UE had used a perfect TA.

[0087] In this disclosure, a “flag” that may be conveyed via signaling typically refers to a binary indication, i.e. an indication that may have only two possible values, e.g. a single-bit indicator. A “flag” may also refer to an indicator that may have only one possible value, while absence of the indicator in a certain signaling message implicitly indicates the other value.

[0088] In this disclosure, “presence of a UE transmission timing error” (which e.g. may be indicated / reported via signaling) means that a UE transmission timing error occurred.

[0089] The above and further related embodiments are now described in detail below.

[0090] The complete procedure of the main embodiment including an essential aspect of the invention is described briefly below. The procedure contains both prior art and inventive steps. In the following discussion, references to step numbers (e.g., messages) are made tocombined Figures 1A and IB of the present disclosure (further reference can be made to TS 38.401 version 18.5.0, figure 8.2.1.5-1):

[0091] Step 1 - The CU logs information about all LTM-related mobility events in an LTM UE mobility history and keeps it in memory while the UE is still connected to this CU. This information can comprise the following elements (but is not limited to):• source cell ID• target cell ID• absolute time of event

[0092] Step 2 - The CU receives message 19 (DU-CU CELL SWITCH NOTIFICATION) from the target DU and uses it to discover ping-pong. The CU uses the information contained in the LTM UE mobility history to detect LTM ping-pong.

[0093] Step 3 - The CU, after discovering a ping-pong, assembles an Information Element (IE) for notifying DUs about ping-pong, by collecting information from the UE context (which now includes the new LTM UE mobility history) and message 19, using fields in message 19 to locate the UE context. This IE contains one or more of the following:• an indication that an LTM ping-pong event was detected for this UE.• information about the previous mobility event, comprising one or more of the following information:a. previous (source) cell ID;b. previous (source) cell type; orc. the time the UE stayed in the previous (source) cell• optionally, information about more than one previous mobility events

[0094] Step 4 - The CU adds the IE created in the previous steps to message 20 (CU-DU CELL SWITCH NOTIFICATION) to the source DU, or to another existing F1AP message sent from CU to DU, or to a new Fl AP message sent from CU to DU.

[0095] Step 5 - The DU uses the ping-pong IE to modify mobility in order to lessen the risk of future ping-pongs.

[0096] Step 6 - Furthermore, taking steps 3-4 for a ping-pong-ping situation, the “other” DU can also be notified of the ping-pong situation, and act according to step 5.

[0097] The steps above are detailed below:

[0098] Steps 1 and 2: The CU finds ping-pong events by keeping a list of LTM cell switches for each connected UE. For each LTM cell switch, the CU adds one entry to the list,and records the time when the cell switch occurred. Entries in this list are deleted after an amount of time defined as the time a ping-pong can occur for a UE.

[0099] Using the definition above, when an LTM cell switch occurs for a UE, for example from cell A to cell B, the CU looks into the list to see if the UE did a previous LTM cell switch from cell A to another cell. If this is the case, a ping-pong event has occurred.

[0100] This procedure for finding ping-pong can also discover ping-pong between more than two cells, for example when there are quick cell switches like A -> B -> C -> A, or even longer chains of cell switches. It can also discover ping-pong for other mobility mechanisms, for example when the mobility from B to C uses another mobility mechanism.

[0101] Step 3: When the CU finds out that a ping-pong has occurred, it collects information from message 19 and the UE context (including the new LTM UE mobility history) in the CU. Specifically, it collects the identity of the target node of the previous LTM cell switch. For example, if there were cell switches of the from A -> B -> A, the target node is cell “B”. This is the cell switch direction that the DU of cell A may want to optimize.

[0102] Step 4: The CU creates an Information Element (IE) for notifying the DU controlling cell A that a ping-pong has occurred. The IE contains at least two items; the first being that a ping-pong has occurred, and the second information about the cell that was the target for the first leg of the ping-pong, is this case cell B. This IE is added to message 20, or another existing F1AP message, or a new F1AP message, and sent to the DU controlling cell A. Information about multiple previous steps can also be included.

[0103] Step 5: The DU uses the ping-pong IE to modify its mobility parameters (e.g. measurement configuration, mobility offset, ... ) in order to lessen the risk of future ping-pongs.

[0104] Step 6: The procedure according to these and other embodiments can be extended to include sending the ping-pong notification to other nodes in the ping-pong chain and not only cell A in the example above. This can be achieved if the ping-pong is allowed to continue for another cell switch. For example, if there is a ping-pong that, if left undisturbed, causes cell switches in the pattern A -> B -> A -> B, the ping-pong will be discovered when reaching cell A the second time as described in the previous step, but also when the UE reaches cell B the second time. The same procedure can then be used to signal that a ping-pong occurred to the DU controlling cell B.

[0105] This procedure can be generalized to any length of ping-pong chains, for example the chain A -> B -> C -> A described above.

[0106] Although these embodiment have been described with regard to certain particular example details, these embodiments are not limited to the example details. More general operations and corresponding methods are now described in the context of the flowcharts of Figures 3 and 4.

[0107] Figure 3 illustrates a flowchart of operations that can be performed by a CU in a communications network. The operations include logging 300 information about LTM-related mobility events in an LTM UE mobility history residing in memory while the UE remains connected to the CU. The operations receive 310 LTM-related information (e.g., which may be in one or more LTM-related messages or in one or more information elements) for a LTM cell switch relating to the UE and a DU. The operations detect 320 ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history. Based on the detecting of the ping-pong LTM cell switches, the operations generate 330 an information element (IE) indicating that an LTM ping-pong event was detected for the UE. The operations then send 340 other LTM-related information (e.g., which may be in one or more other LTM-related messages) containing the IE to the DU and / or to another DU.

[0108] The logging 300 of information may include, for each LTM cell switch of the UE adding an entry to a list in the LTM UE mobility history to indicate the LTM cell switch of the UE occurred and a time when the LTM cell switch occurred. The operations may also delete an entry in the list in the LTM UE mobility history responsive to the entry having an indicated time when the LTM cell switch occurred that exceeds a threshold time defined as associated with ping-pong LTM cell switches.

[0109] The logging 300 of information may include logging at least one of a source cell identifier, a target cell identifier, or an absolute time of the mobility event for the UE into the LTM UE mobility history.

[0110] The receiving 310 of the LTM-related information (e.g., LTM-related message(s) or IE(s)) for the LTM cell switch relating to the UE and the DU, may include receiving a DU-CU cell switch notification indicating a target cell ID and a Transmission Configuration Indicator (TCI) state ID.[oni] The detecting 320 of ping-pong LTM cell switches of the UE between two cells may include, responsive to determining from content of the LTM-related information (e.g., LTM-related message(s) or IE(s)) that a LTM cell switch has been triggered for the UE,determining from a list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell.

[0112] This determining from the list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell, may include determining that the present LTM cell switch and the previous cell switch of the UE were controlled by different DUs.

[0113] The generating 330 of the IE indicating that the LTM ping-pong event was detected for the UE, may include generating the IE to include information indicating at least one of:• a source cell ID;• a target cell ID;• an absolute time for the LTM cell switch;• a previous source cell type of a previous LTM cell switch of the UE;• a previous target cell ID of the previous LTM cell switch of the UE;• a previous target cell type of the previous LTM cell switch of the UE; • a time duration that the UE spent in a previous cell before a LTM cell switch;and• an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.

[0114] The generating 330 of the IE indicating that the LTM ping-pong event was detected for the UE, may include generating the IE to include information indicating at least one of:• an indication that the target DU or the another DU is to operate to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;• an indication that the target DU and the another DU are both to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;• an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;• an indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;• an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs; and• an indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs.

[0115] The sending 340 of the other LTM-related information (e.g., LTM-related message(s)) containing the IE to the DU and / or to another DU, may include sending the IE in a CU-DU cell switch notification or a Fl interface application protocol message.

[0116] Figure 4 illustrates a flowchart of operations that can be performed by a DU in a communications network. The operations include receiving 400 LTM-related information (e.g., LTM-related message(s)) containing an IE indicating that a CU detected an LTM ping-pong event characterized by ping-pong LTM cell switches of a UE between at least two cells. The operations further include adapting 410 mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE.

[0117] The adapting 410 of the mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, may include adapting a measurement configuration parameter and / or a mobility offset parameter used to control present or future LTM cell switch of the UE or other UEs, based on the IE.

[0118] The operations may further include identifying based on the IE at least one of:• a source cell ID;• the target cell ID;• an absolute time for the LTM cell switch;• a previous source cell type of a previous LTM cell switch of the UE;• a previous target cell ID of the previous LTM cell switch of the UE;• a previous target cell type of the previous LTM cell switch of the UE; • a time duration that the UE spent in a previous cell before a LTM cell switch;and• an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.

[0119] The adapting 410 of the mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, may include at least one of:• adapting a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;• adapting a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs; and• adapting a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs.

[0120] The received 400 LTM-related information (e.g., LTM-related message(s)) may include a CU-DU cell switch notification or a Fl interface application protocol message.

[0121] Examples of additional information that can be included in the CU-DU signaling are now described for additional or alternative embodiments.

[0122] When a CU detects frequent cases of ping-pong LTM cell switches between two cells controlled by different ones of the CU’s DUs, the CU can inform one or both of the involved DUs and add further information guiding the DU(s) in how to resolve / improve the situation. Such further information may e.g. be guiding information or instruct! on(s), e.g. one or more of:• Ping-pong LTM cell switches have been detected between cell X and cell Y.• Ping-pong mobility between cell X and cell Y has been detected (where at least one of the mobility procedures was an LTM cell switch).• Ping-pong LTM cell switches have been detected between cell X and cell Y for UE Z (where the indication of the UE may be explicit, e.g. using a UE identifier, or implicit by using UE associated F1AP signaling).• Ping-pong mobility between cell X and cell Y has been detected (where at least one of the mobility procedures was an LTM cell switch, and where the indication of the UE may be explicit, e.g. using a UE identifier, or implicit by using UE associated F1AP signaling).• An identifier of the previous cell in the ping-ponging (e.g. the source cell of the LMT cell switch for which the cell controlled by the DU was the target cell).• The cell type of the previous cell in the ping-ponging (e.g. the source cell of the LMT cell switch for which the cell controlled by the DU was the target cell).• The time duration spent in the previous cell in the ping-ponging (e.g. the source cell of the LMT cell switch for which the cell controlled by the DU was the target cell).a. The average time duration for UEs averaged over many ping-pong procedures, and / orb. The time duration for a certain UE during a certain ping-pong event, wherein the indication of the UE may be explicit, e.g. using a UE identifier, or implicit by using UE associated F1AP signaling).• An indication to a DU that it is responsible for increasing the hysteresis. In this case, as an option, only the DU responsible for increasing the hysteresis needs to be informed.• The other DU is responsible for increasing the hysteresis.• You are both responsible for increasing the hysteresis, i.e. each of you should increase e.g. half the default increment.• Adjust a channel quality quantity (e.g. RSRP, RSRQ, SINR, SNR, RSSI) offset by an X defined or indicated amount.• Adjust a channel quality quantity (e.g. RSRP, RSRQ, SINR, SNR, RSSI) threshold by an X defined or indicated amount.

[0123] When determining what information and / or instruction(s) to send the DU(s), as well as which DU(s) to send information and / or instructions to (e.g. both or only one, and if only one then which one), the CU could take various aspects into account. For instance, the CU could use as basis at least in part one or more of:• The load (e.g. traffic load) in the respective cells. (The load in the respective cells may be important input data since changing an offset and / or a threshold for LTM cell switch triggering in one of the cells with the intention to increase the hysteresis means that the DU will make UEs stay a bit longer in the cell, which in turn means increasing the average number of UEs in the cell which in turn means increasing the load).a. The current load in the respective cells, orb. The average load in the respective cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The sliding average number of RLF reports and / or SHRs, or the number of or frequency of RLF reports and / or SHRs during a recent time period, associated with the DUs or cells controlled by the DUs, e.g. cells involved in frequent and / or detected ping-pong LTM cell switch sequences (or ping-pong mobility sequences which may consist of mixtures of LTM cell switches and othermobility procedures). This can provide an indication of the recent performance of the DU(s) which can be taken into account in deciding if the DU(s) can bear the additional load involved in mitigating ping-pong LTM cell switches, e.g. taking on more UEs as a result of adjusting parameters controlling LTM cell switch execution triggering or mobility triggering, and if so, which of them is better suited.• LTM cell switch failures (and optionally other mobility failures) occurring during ping-pong LTM cell switch sequences (and optionally during mobility ping-pong sequences, e.g. consisting of mixes of LTM cell switches and handovers). If a ping-pong LTM cell switch sequence (or a ping-pong mobility sequence) ends with an LTM cell switch failure (or a mobility failure) towards a certain one of the involved cells, or if this happens frequently (e.g. more frequently than that ping-pong LTM cell switch sequences end (or more frequently than that ping-pong mobility sequences end) with LTM cell switch failures (or mobility failures) towards the other cell), then that may imply that the source cell of the failing LTM cell switch (or failing mobility) is the one for which parameters controlling LTM cell switch execution triggering (or mobility execution triggering), e.g. offset(s) and / or threshold(s) should be adjusted in order to increase the hysteresis. Note that this does not exclude that such parameters for the other cell are also adjusted in order to increase the hysteresis, albeit to a lesser extent.• The total capacity of each of the involved cells (e.g. in terms of total maximum throughput or traffic load that can be handled).• The composite available capacity of the respective cells (total, or separately in downlink and uplink).a. The current composite available capacity of the respective cells, or b. The average composite available capacity of the respective cells (e.g.calculated over a recent time period or as a sliding average or an exponential average).• The number of active UEs in the respective cells.a. The current number of active UEs in the respective cells, orb. The average number of active UEs in the respective cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The number of RRC connection in the respective cells.a. The current number of RRC connection in the respective cells, or b. The average number of RRC connection in the respective cells (e.g.calculated over a recent time period or as a sliding average or an exponential average).• The per slice available capacity for the network slices in the respective cells.a. The current per slice available capacity for the network slices in the respective cells, orb. The average per slice available capacity for the network slices in the respective cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The Transport Network Layer (TNL) Capacity indicator for the respective cells.• The Synchronization Signal Block (SSB) Area Radio Resource Status for the SSB areas in the respective cells, currently or on average (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The remaining unused capacity in each of the involved cells (e.g. in terms of throughput or traffic load that can be handled).a. The current remaining unused capacity in each of the cells, or b. The average remaining capacity in each of the involved cells (e.g.calculated over a recent time period or as a sliding average or an exponential average).• The relative load (e.g. traffic load) in each of the cells, i.e. the load divided by the maximum load the cell can handle.a. The current relative load in each of the cells, orb. The average relative load in each of the cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The relative used capacity in each of the cells, i.e. the used capacity divided by the total capacity.a. The current relative used capacity in each of the cells, orb. The average relative used capacity in each of the cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The relative unused capacity in each of the cells, i.e. the unused capacity divided by the total capacity.a. The current relative unused capacity in each of the cells, orb. The average relative unused capacity in each of the cells (e.g. calculated over a recent time period or as a sliding average or an exponential average).• The number of connected UEs in each of the cells. (The number of connected UEs in the respective cells may be important input data since changing an offset and / or a threshold for LTM cell switch triggering in one of the cells with the intention to increase the hysteresis means that the DU will make UEs stay a bit longer in the cell, which in turn means increasing the average number of UEs in the cell which in turn means increasing the load).a. The current number of connected UEs in each of the two cells, or b. The average number of connected UEs in each of the two cells (e.g.calculated over a recent time period or as a sliding average or an exponential average).• The L3 measurements reported by the UE for each of the involved cells. The rationale is that probably one of cells is slightly better, and then it is better that that is the cell that retains the UE a bit longer, and then it is in that cell that offset(s) and / or threshold(s) governing the LTM cell switch execution decisions should be adjusted to increase the hysteresis. This may be the most relevant for the semi-real-time stopping of an ongoing ping-ponging for a certain UE, but can also be used for more long-term adjustments for all UEs based on statistics.• In which cell the ping-ponging ends (unless it ends up in LTM failure, handover failure or RLF, or by semi-real -time adjustments of offset(s) and / or threshold(s)), i.e. the cell in which the UE remains when the ping-ponging has ended, provided that it ends without failure or intervention (e.g. configuration changes) from the network. A potential conclusion of this piece of input information may be that that cell is probably the main culprit (i.e. the main causes of the ping-ponging) and should adjust its threshold(s) and / or offset(s).• If the ping-pong sequence also involved one or more L3 handover(s), and the CU triggered L3 handover(s) (or the UE autonomously triggered conditional handover(s)) in only one of the two ping-pong directions, this may be an indication that the target cell of that / those handover(s) is the main culprit and should adjust its threshold(s) and / or offset(s).• Reported measurement results from one or more UE(s) involved in ping-pong mobility, in particular ping-pong LTM cell switches, between the two involved cells, e.g. reported L3 measurement results, wherein the reported measurement results were obtained in the two involve cells.

[0124] Although these embodiment have been described with regard to certain particular example details, these embodiments are not limited to the example details. More general operations and corresponding methods are now described with further reference to the flowcharts of Figure 3.

[0125] The operations by the CU may further include determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:• current communication resource load utilization in the DUs;• average of the resource load utilization in the DUs;• sliding average of number of radio link failure reports and / or successful handover reports of the DUs;• sliding average of number of or frequence of radio link failure reports and / or successful handover reports associated with the DUs or cells controlled by the DUs;• LTM cell switch failures occurring during ping-pong LTM cell switch sequences involving the DUs;• total capacity of the respective cells controlled by the DUs;• composite available capacity of the respective cells controlled by the DUs; • number of active UEs in the respective cells controlled by the DUs;• number of radio resource control, RRC, connections in the respective cells controlled by the DUs;• per slice available capacity for network slices in the respective cells controlled by the DUs; and• Transport Network Layer, TNL, capacity for the respective cells controlled by the DUs.

[0126] The operations by the CU may further include determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:• Synchronization Signal Block (SSB) Area Radio Resource Status for the SSB areas in the respective cells controlled by the DUs;• remaining unused communication resource capacity in the respective cells controlled by the DUs;• comparison between the DUs of relative communication resource load of respective cells controlled by the DUs;• comparison between the DUs of a ratio of used communication resource capacity and total communication resource capacity of the respective DUs; and • comparison between the DUs of a ratio of unused communication resource capacity and total communication resource capacity of the respective DUs.

[0127] The operations by the CU may further include determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:• number of connected UEs in the respective cells controlled by the DUs; • L3 measurements reported by the UE;• in which cell of which of the DUs the UE remains when the ping-pong switching is determined to end;• which of the DUs involved in ping-pong LTM cell switches with the UE was also involved in a L3 handover; and• reported measurement results from other UEs involved in ping-pong LTM cell switches.

[0128] When both or any one of the involved DUs receive the information and / or instruction(s), a DU may evaluate the received information from the CU, where the evaluation may include one or more of the following determinations:• If the DU is able to handle the ping-pong issue, a message or an indication can be sent back to the CU informing that the ping-pong is handled and / or the suggested instruction(s) from the CU is(are) executed.• If the DU is unable to handle the ping-pong issue, or if the DU evaluates that it is not its responsible to handle the ping-pong issue, the DU may send a message or an indication to the CU informing that it cannot resolve the ping-pong, or theDU may not send any response message to the CU, which can be used for the CU as an implicit indication that the DU has not resolved the ping-pong.• The DU can indicate to the CU that the other involved DU should be responsible for this ping-pong issue.• The DU can send to the CU of the LTM cell switch mobility change suggestions that the CU may forward to the other involved DU. The suggested LTM cell switch mobility change can be, e.g. adjust a channel quality quantity (e.g. RSRP, RSRQ, SINR, SNR, RSSI) offset by X, adjust a channel quality quantity (e.g. RSRP, RSRQ, SINR, SNR, RSSI) threshold by X, adjust conditional LTM conditions etc.

[0129] More general operations and corresponding methods by the DU are now described with further reference to the flowcharts of Figure 4.

[0130] The operations by the DU may further include sending a response message to the CU indicating that DU has adapted based on the CU indicated detection of the LTM ping-pong event.

[0131] The operations by the DU may further include sending a response message to the CU indicating that DU has not adapted based on the CU indicated detection of the LTM ping-pong event.

[0132] The operations by the DU may further include sending a response message to the CU indicating that another DU is responsible for adapting based on the CU indicated detection of the LTM ping-pong event.

[0133] The operations by the DU may further include sending in the response message to the CU an indication of LTM cell switch mobility change suggestions that the CU can forward to the another DU.

[0134] Various additional or alternative embodiments are now described for performing ping-pong LTM cell switch detection. Any one or more of these embodiments may be combined in any manner.

[0135] In one embodiment a CU detects ping-pong LTM cell switches between two cells controlled by the same DU connected to the CU, e.g. by observing the cell identities of the cells serving the UEs before the CU received from the source DU first message (e.g. DU-CU CELL SWITCH NOTIFICATION messages or ACCESS SUCCESS messages) indicating that the UEs were moved to another cell, and the cell identities comprised in first or second messages the CU received from the DU (e g., DU-CU CELL SWITCH NOTIFICATION messages orACCESS SUCCESS messages), indicating the cells towards which the DU moved the UEs with the LTM Cell Switch Command.

[0136] In another embodiment, a DU detects ping-pong LTM cell switches between two cells of the DU e.g. by observing the cell identities of the cells serving UEs before the DU sent the LTM Cell Switch commands to the UEs and the cell identities towards which the DU moved the UEs with the LTM Cell Switch Commands. The DU provides assistance information to the CU, to indicate the presence of ping-pong LTM cell switches.

[0137] In another embodiment a CU detects ping-pong Conditional LTM cell switches between two cells controlled by different DUs controlled by the CU, e.g. by observing the cell identities of the cells serving the UEs before the CU received from the target DU first messages (e.g., a DU-CU CELL SWITCH NOTIFICATION messages or ACCESS SUCCESS messages) indicating that the UEs moved to another cell, and the cell identities comprised in first or second messages the CU received from the target DU (e.g., DU-CU CELL SWITCH NOTIFICATION messages or ACCESS SUCCESS messages), indicating the cells towards which the UEs moved with Conditional LTM Cell Switch.

[0138] In another embodiment a CU detects ping-pong Conditional LTM cell switches between two cells controlled by the same DU controlled by the CU, e.g. by observing the cell identities of the cells serving the UEs before the CU received from the DU in its role as target DU first messages (e.g. DU-CU CELL SWITCH NOTIFICATION messages or ACCESS SUCCESS messages) indicating that the UEs moved to another cell, and the cell identities comprised in first or second messages the CU received from the DU in its role as target DU (e.g., DU-CU CELL SWITCH NOTIFICATION messages or ACCESS SUCCESS messages), indicating the cells towards which the UEs moved with Conditional LTM Cell Switch.

[0139] More general operations and corresponding methods are now described with further reference to the flowcharts of Figure 3.

[0140] The detecting 320 of ping-pong LTM cell switches of the UE may include comparing cell identity of a cell serving the UE before the CU received from a source DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the source DU indicating the cell towards which the DU moved the UE based on a LTM Cell Switch Command.

[0141] The detecting 320 of ping-pong LTM cell switches of the UE may include comparing cell identity of a cell serving the UE before the CU received from a target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the firstmessage or a second message the CU received from the target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

[0142] The detecting 320 of ping-pong LTM cell switches of the UE may include comparing cell identity of a cell serving the UE before the CU received from the DU in its roles as target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the DU in its roles as target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

[0143] In another embodiment, a DU detects ping-pong Conditional LTM cell switches between two cells of the DU e.g. by observing the cell identities of the cells serving UEs before the DU in its role of source (or serving) DU received first messages (e.g., CU-DU CELL SWITCH NOTIFICATION messages) indicating that the UE moved away from the source cell, and the cell identities comprised in first or second messages (e.g., CU-DU CELL SWITCH NOTIFICATION messages or CU-DU CONDITIONAL CELL SWITCH NOTIFICATION messages), indicating the cells towards which the UEs moved with Conditional LTM Cell Switch. The DU provides assistance information to the CU, to indicate the presence of ping-pong Conditional LTM cell switches.

[0144] More generate operations by the DU are now described with reference to Figure 4.

[0145] The operations by the DU may further include detecting ping-pong LTM cell switches of the UE between at least two cells of the DU based on comparing cell identity of a cell serving the UE before the DU in its role of source DU received a first message indicating that the UE moved away from the cell of the source DU, and a cell identity comprised in the first message or a second message the CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

[0146] In another embodiment a first CU detects ping-pong LTM cell switches between two cells, a first controlled by the first CU (gNB), and a second cell controlled by a second CU (gNB), e.g. by observing the cell identities of the cells serving the UEs before the first CU received from the second CU (gNB) first messages (e.g. CELL SWITCH NOTIFICATION XnAP messages) indicating that the UEs moved to another cell, and the cell identities comprised in first or second messages the first CU received from the second CU (e.g., CELL SWITCH NOTIFICATION XnAP messages), indicating the cells towards which the UEs moved due to LTM Cell Switch.

[0147] More general operations and corresponding methods are now described with further reference to the flowcharts of Figure 3.

[0148] In Figure 3, the CU can be referred to as a first CU. The detecting 320 of ping-pong LTM cell switches of the UE between at least two cells may include detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a LTM Cell Switch.

[0149] In another embodiment a first CU detects ping-pong Conditional LTM cell switches between two cells, a first controlled by the first CU (gNB), and a second cell controlled by a second CU (gNB), e.g. by observing the cell identities of the cells serving the UEs before the first CU received from the second CU (gNB) first messages (e.g. CELL SWITCH NOTIFICATION XnAP messages) indicating that the UEs moved to another cell, and the cell identities comprised in first or second messages the first CU received from the second CU (e.g., CELL SWITCH NOTIFICATION XnAP messages), indicating the cells towards which the UEs moved due to Conditional LTM Cell Switch.

[0150] More general operations and corresponding methods are now described with further reference to the flowcharts of Figure 3.

[0151] In Figure 3, the CU can be referred to as a first CU. The detecting 320 of ping-pong LTM cell switches of the UE between at least two cells may include detecting ping-pong Conditional LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

[0152] In another embodiment, the CU detects ping-pong LTM cell switches between cells controlled by different DUs and decides to “anchor” the UE to a particular DU if the signal quality quantities (e.g. RSRP, RSRQ, SINR, SNR, RS SI) are above a threshold, and informs the concerned DU of this decision. The UE in this case is not sent any LTM cell switch command for a certain time even if the LI measurements indicate that the conditions aresuitable for an LTM cell switch. This prevents any ping-pong LTM cell switches for this time period.

[0153] More general operations and corresponding methods are now described with further reference to the flowcharts of Figure 3.

[0154] In Figure 3, the CU can be referred to as a first CU. The detecting 320 of ping-pong LTM cell switches of the UE between at least two cells may include detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, and responsive to the detecting preventing further LTM cell switch of the UE while the a signal quality quantity is above a defined threshold.

[0155] These and and other embodiments which are disclosed or understood from the present disclosure can be implemented and operate with the components of various communication systems described below.

[0156] Figure 5 shows an example of a communication system QQ100 in accordance with some embodiments.

[0157] In the example, the communication system QQ100 includes a telecommunications network QQ102 that includes an access network QQ104, such as a radio access network (RAN), and a core network QQ106, which includes one or more core network nodes QQ108. The access network QQ104 includes one or more access network nodes or base stations of various types, access network nodes QQ110A and QQ110B are depicted (which may be collectively referred to as network nodes QQ110), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points (APs). Some embodiments of the access network QQ104 may include more than one access network technology. The network nodes QQ110 of access network QQ104 facilitate direct or indirect connection of wireless devices, also referred to as user equipments (UEs), such as by connecting UEs QQ112A, QQ112B, QQ112C, and QQ112D (one or more of which may be generally referred to as UEs QQ112) to the core network QQ106 over one or more wireless connections.

[0158] Moreover, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunications network QQ102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a network node in the telecommunications network QQ102 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operatealone or together with other network nodes to implement one or more functionalities of any network node in the telecommunications network QQ102, including one or more access network nodes QQ110 and / or core network nodes QQ108.

[0159] 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 anon-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). An ORAN network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN network node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (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 0-2 interface defined by the 0-RAN Alliance or comparable technologies.

[0160] The network nodes QQ110 facilitate direct or indirect connection of one or more UEs QQ112 to the core network QQ106 over one or more wireless connections. Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system QQ100 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system QQ100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0161] The UEs QQ112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes QQ110 and other communication devices. Similarly, the network nodes QQ108, QQ110 are arranged, capable, configured, and / or operable to communicate directly orindirectly (e.g., via other devices of telecommunications network QQ102) with the UEs QQ112 and / or with other network nodes or equipment in the telecommunications network QQ102 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunications network QQ102. More specifically, UEs QQ112 may send messages, data, and / or other signals to network nodes QQ108, QQ110 or other elements of the telecommunications network QQ102 by transmitting such signals to the relevant device directly without the signals passing through any intervening devices or by transmitting such signals to the relevant device indirectly through an intervening device (or multiple intervening devices) that then transmit the signal to the relevant device. Similarly, network nodes QQ108, QQ110 may send messages, data, and other signals to UEs QQ1122, other network nodes QQ108, QQ110, and other devices in telecommunications network QQ102 directly or indirectly. As one specific example, a core network node 108 may transmit a particular message to a UE QQ112 by transmitting the message to an access network node QQ110 that will then transmit the message to the intended UE QQ112. Similarly, a core network node 108 may receive a particular message from a UE QQ112 by receiving the message from an access network node QQ110 that itself received the message from the UE QQ112.

[0162] In the depicted example, the core network QQ106 connects elements of the access network QQ104 (e.g., one or more of the network nodes QQ110) to one or more host computing systems, such as host QQ116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network QQ106 includes one or more core network nodes (e.g., core network node QQ108) of various types, one or more of which may be generally referred to as network nodes QQ108. Network nodes QQ108 are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, access network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node QQ108. Example core network nodes provide 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).

[0163] The host QQ116 may be under the ownership or control of a service provider other than an operator or provider of the access network QQ104 and / or the telecommunications network QQ102. The host QQ116 may be operated by the service provider or on behalf of the service provider. The host QQ116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0164] As a whole, the communication system QQ100 of Figure 5 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system QQ100 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 (Wi-Fi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (Wi-Max), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, Li-Fi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox. Moreover, the communication system QQ100 may be configured to support multiple different standards, protocols, or other rule sets, with individual components supporting all of the relevant rule sets or with different components or sub-systems within the communication system QQ100 supporting different standards, protocols, or rule sets.

[0165] As one example, in certain embodiments, access network QQ104 may contain some access network nodes QQ110 that support 3GPP radio access technologies (RAT), such as LTE or NR, while other access network nodes QQ110 support (or the same access network nodes QQ110 additionally support) non-3GPP RATs, such as Wi-Fi or a proprietary RAT. As another example, telecommunications network QQ102 may support multiple generations of related communication standards (e.g., 4G and 5G 3GPP communication standards) and, as a result, may include an access network 104 and / or a core network 106 that supports multiple different standard generations or may include multiple access networks 104 and / or multiplecore networks 106 with individual networks 104, 106 supporting different standard generations.

[0166] Telecommunications network QQ102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunications network QQ102. For example, the telecommunications network QQ102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0167] In some examples, one or more of the UEs QQ112 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network QQ104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network QQ104. Additionally, a UE may be configured for operating in single- or multi -RAT or multistandard 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).

[0168] In the example, the hub QQ114 communicates with the access network QQ104 to facilitate indirect communication between one or more UEs (e.g., UE QQ112C and / or QQ112D) and network nodes (e.g., network node QQ110B). In some examples, the hub QQ114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub QQ114 may be a broadband router enabling access to the core network QQ106 for the UEs. As another example, the hub QQ114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes QQ110, or by executable code, script, process, or other instructions in the hub QQ114.

[0169] As another example, the hub QQ114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub QQ114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub QQ114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub QQ114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hubQQ114 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0170] The hub QQ114 may have a constant / persistent or intermittent connection to the network node QQ110B. The hub QQ114 may also allow for a different communication scheme and / or schedule between the hub QQ114 and UEs (e.g., UE QQ112C and / or QQ112D), and between the hub QQ114 and the core network QQ106. In other examples, the hub QQ114 is connected to the core network QQ106 and / or one or more UEs via a wired connection. Moreover, the hub QQ114 may be configured to connect to an M2M service provider over the access network QQ104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes QQ110 while still connected via the hub QQ114 via a wired or wireless connection. In some embodiments, the hub QQ114 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node QQ110B. In other embodiments, the hub QQ114 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node QQ110B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0171] Figure 6 is another example of a communication system QQ200 according to some embodiments. As used herein, the communication system QQ200 includes multiple access points (APs) QQ210 (with four exemplary APs QQ210A, QQ210B, QQ210C, and QQ210D being depicted) and multiple wireless devices, referred to in the context of communication system QQ200 as stations (STAs) QQ212 (referred to individually as STA QQ212A, STA QQ212B, STA QQ212C, STA QQ212D, and STA QQ212E). STA QQ212A is served by AP QQ210A in a first basic service set (BSS) QQ220A. STA QQ210B and STA QQ210C are served by AP QQ210B in a second BSS, BSS QQ220B. STA QQ212D is served by AP QQ210C in a third BSS, BSS QQ220C. STA QQ212E is served by AP QQ210D in a fourth BSS, BSS QQ220D. Stations QQ212 may be non-AP STAs and correspond to various kinds of wireless devices, for example, user terminals, such as mobile or stationary computing devices like smartphones, laptop computers, desktop computers, tablet computers, gaming devices, head-mounted displays (HMDs) for Augmented Reality (AR) or Virtual Reality (VR), or the like. Further, stations QQ212 could, for example, correspond to other kinds of equipment like smart home devices, printers, multimedia devices, data storage devices, or the like.

[0172] Each of STAs QQ212 may connect through a radio link to one of APs QQ210. For example, depending on location or channel conditions experienced by a given STA QQ212,the STA may select an appropriate AP and BSS for establishing the radio link. The radio link may be based on one or more orthogonal frequency-division multiplexing (OFDM) carriers from a frequency spectrum that is shared on the basis of a contention-based mechanism, e.g., an unlicensed or license exempt band like 2.4 GHz Industrial, Scientific, and Medical (ISM) band, the 5 GHz band, the 6 GHz band, or the 60 GHz band.

[0173] Each AP QQ210 may provide data connectivity to STAs QQ212 connected to a particular AP QQ210. As illustrated, APs QQ210 may be connected to a data network QQ230. In this way, APs QQ210 may also provide data connectivity between STAs QQ212 and other entities, e.g., to one or more servers, service providers, data sources, data sinks, user terminals, or the like. Accordingly, the radio link established between a given STA QQ212 and its serving AP QQ210 may be used for providing various kinds of services to STA QQ212, e.g., a voice service, a multimedia service, or other data service. Such services may be based on applications that are executed on STA QQ212 and / or on a device linked to STA QQ212. By way of example, Figure 6 illustrates an application service platform QQ232 provided in data network QQ230. The application(s) executed on STA QQ212 and / or on one or more other devices linked to STA QQ212 may use the radio link for data communication with one or more other STA QQ212 and / or the application service platform QQ232, thereby enabling utilization of the corresponding service(s) at STA QQ212.

[0174] Figure 7 shows a wireless device QQ300, which may be configured to operate in communication system QQ100 of Figure 5 or in communication system QQ200 of Figure 6. The wireless device QQ300 may be alternatively referred to as a UE QQ300, like a UE QQ112 within the context of communication system QQ100, or as a station (STA) QQ300 or as a nonaccess-point station (non-AP STA) QQ300, like a STA QQ212 within the context of the communication system QQ200, in accordance with respective embodiments. As used herein, a wireless device refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Examples of a wireless device 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, and wireless terminal. Other examples include any type of UE identified by the 3rd GenerationPartnership Project (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.

[0175] A wireless device QQ300 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, wireless device QQ300 may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, wireless device QQ300 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, wireless device QQ300 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).

[0176] In particular embodiments, wireless device QQ300 includes processing circuitry QQ302 that is operatively coupled via a bus QQ304 to an input / output interface QQ306, a power source QQ308, a memory QQ310, a communication interface QQ312, and / or any other component, or any combination thereof. Certain embodiments of wireless device QQ300 may include all or a subset of the components shown in Figure 7. The level of integration between the components may vary from one embodiment of wireless device QQ300 to another. In general, in a particular embodiment of wireless device QQ300, processing circuitry QQ302, input / output interface QQ306, power source QQ308, memory QQ310, and communication interface QQ312 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of wireless device QQ300. Further, certain embodiments of wireless devices QQ300 may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0177] The processing circuitry QQ302 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory QQ310. The processing circuitry QQ302 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, the processing circuitry QQ302 may include multiple central processing units (CPUs).

[0178] In the example, the input / output interface QQ306 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 wireless device QQ300. 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.

[0179] In some embodiments, the power source QQ308 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 to supply power to circuitry or to charge an associated battery. The power source QQ308 may further include power circuitry for delivering power from the power source QQ308 itself, and / or an external power source, to the various parts of wireless device QQ300 via input circuitry or an interface such as an electrical power cable. Power source QQ308 may perform any formatting, converting, or other modification to make accessible power suitable for the respective components of the wireless device QQ300 to which power is supplied.

[0180] The memory QQ310 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory QQ310 includes one or more programs QQ314, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data QQ316. The memory QQ310 maystore, for use by wireless device QQ300, any of a variety of various operating systems or combinations of operating systems.

[0181] The memory QQ310 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory QQ310 may allow wireless device QQ300 to access instructions, programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory QQ310, which may be or comprise a device-readable storage medium.

[0182] The processing circuitry QQ302 may be configured to communicate with an access network or other network via or using the communication interface QQ312. The communication interface QQ312 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna QQ322. The communication interface QQ312 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 wireless device or a network node in an access network). Each transceiver may include a transmitter QQ318 and / or a receiver QQ320 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter QQ318 and receiver QQ320 may be coupled to one or more antennas (e.g., antenna QQ322) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0183] In the illustrated embodiment, communication functions of the communication interface QQ312 may include cellular communication, Wi-Fi communication (e.g., according to an IEEE 802.11 family standard), 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 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 / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0184] In particular embodiments, wireless device QQ300 may provide an output of data captured via a sensor, through its communication interface QQ312, via a wireless connection to a network node, and / or in any appropriate manner. Data captured by sensors of a wireless device QQ300 can be communicated through a wireless connection to a network node via another wireless device QQ300. In particular embodiments, such 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).

[0185] As another example, wireless device QQ300 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, wireless device QQ300 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.

[0186] Wireless device QQ300, 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, wearable technology, extended industrial application and healthcare. Nonlimiting 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 parkingmonitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, 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. In particular embodiments, wireless device QQ300 represents an loT device that comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the example embodiment of wireless device QQ300 shown in Figure 7.

[0187] As yet another specific example, in an loT scenario, wireless device QQ300 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 wireless device and / or a network node. Wireless device QQ300 may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, wireless device QQ300 may implement the 3GPP NB-IoT standard. In other scenarios, wireless device QQ300 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.

[0188] In practice, any number of wireless devices QQ300 may be used together with respect to a single use case. For example, a first wireless device QQ300 might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second wireless device QQ300 that is a remote controller operating the drone. When a user makes changes from the remote controller, the first wireless device QQ300 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 wireless device QQ300 can also include more than one of the functionalities described above. For example, wireless device QQ300 might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0189] Figure 8 shows a network node QQ400 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunications network. In accordance with respective embodiments, network node QQ400 may be configured to operate in communication system QQ100 of Figure 5, like network nodes QQ108 or QQ110, or in communication system QQ200 of Figure 6, like an APQQ210 or a station QQ212. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0190] Network nodes QQ400 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. Network node QQ400 may be a relay node or a relay donor node controlling a relay. Network nodes QQ400 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 O-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).

[0191] Other examples of network nodes QQ400 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).

[0192] In particular embodiments, network node QQ400 includes a processing circuitry QQ402, a memory QQ404, a communication interface QQ406, and a power source QQ408. In general, in a particular embodiment of network node QQ400, processing circuitry QQ402, memory QQ404, communication interface QQ406, and power source QQ408 may, in whole or in part, represent or include physical components common to or shared by one or more of the other elements of network node QQ400.

[0193] The network node QQ400 may be composed of multiple distinct network entities (e.g., a NodeB entity and a RNC entity, or a BTS entity and a BSC entity, etc.), which may each have or utilize their own respective physical components. In certain scenarios in which the network node QQ400 comprises multiple such entities (e.g., BTS and BSC), one or more of the separate entities may be shared among several network nodes. For example, a singleRNC 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, the network node QQ400 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories QQ404 or portions of memory QQ404 for different RATs) and some components may be reused (e.g., a same antenna QQ410 may be shared by different RATs). The network node QQ400 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node QQ400, for example GSM, WCDMA, LTE, NR, Wi-Fi (e.g., according to an IEEE 802.11 family standard), 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 QQ400.

[0194] The processing circuitry QQ402 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 components, such as the memory QQ404, to provide network node QQ400 functionality.

[0195] In some embodiments, the processing circuitry QQ402 includes a system on a chip (SOC). In some embodiments, the processing circuitry QQ402 includes one or more of radio frequency (RF) transceiver circuitry QQ412 and baseband processing circuitry QQ414. In some embodiments, the RF transceiver circuitry QQ412 and the baseband processing circuitry QQ414 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 QQ412 and baseband processing circuitry QQ414 may be on the same chip or set of chips, boards, or units.

[0196] The memory QQ404 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computerexecutable memory devices that store information, data, and / or instructions that may be used by the processing circuitry QQ402. The memory QQ404 may store any suitable instructions,data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry QQ402 and utilized by the network node QQ400. The memory QQ404 may be used to store any calculations made by the processing circuitry QQ402 and / or any data received via the communication interface QQ406. In some embodiments, the processing circuitry QQ402 and memory QQ404 is integrated.

[0197] The communication interface QQ406 is used in wired or wireless communication of signaling and / or data with UEs, other network nodes, and / or any other network equipment. In the illustrated embodiment, communication interface QQ406 comprises port(s) / terminal(s) QQ416 to send and receive data, for example to and from a network over a wired connection. In particular embodiments, network node QQ300 may be capable of wireless communication and communication interface QQ406 may also include radio front-end circuitry QQ418 that may be coupled to, or in certain embodiments a part of, an antenna QQ410. Particular embodiments of radio front-end circuitry QQ418 include filter(s) QQ420 and amplifier(s) QQ422. The radio front-end circuitry QQ418 may be connected to an antenna QQ410 and processing circuitry QQ402. The radio front-end circuitry may be configured to condition signals communicated between antenna QQ410 and processing circuitry QQ402. The radio front-end circuitry QQ418 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry QQ418 may convert the digital data into a radio signal(s) having the appropriate channel and bandwidth parameters using a combination of filters QQ420 and / or amplifiers QQ422. The radio signal(s) may then be transmitted via the antenna QQ410. Similarly, when receiving data, the antenna QQ410 may collect radio signals which are then converted into digital data by the radio front-end circuitry QQ418. The digital data may be passed to the processing circuitry QQ402. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0198] In certain alternative embodiments, network node QQ400 may be capable of wireless communication but does not include separate radio front-end circuitry QQ418, instead, the processing circuitry QQ402 includes radio front-end circuitry and is connected to the antenna QQ410. Similarly, in some embodiments, all or some of the RF transceiver circuitry QQ412 is part of the communication interface QQ406. In still other embodiments, the communication interface QQ406 includes one or more ports or terminals QQ416, the radio front-end circuitry QQ418, and the RF transceiver circuitry QQ412, as part of a radio unit (notshown), and the communication interface QQ406 communicates with the baseband processing circuitry QQ414, which is part of a digital unit (not shown).

[0199] The antenna QQ410 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna QQ410 may be coupled to the radio front-end circuitry QQ418 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna QQ410 is separate from the network node QQ400 and connectable to the network node QQ400 through one or more interfaces or ports.

[0200] The antenna QQ410, communication interface QQ406, and / or the processing circuitry QQ402 may be configured to perform some or all of the receiving operations and / or obtaining operations described herein as being performed by the network node QQ400. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna QQ410, the communication interface QQ406, and / or the processing circuitry QQ402 may be configured to perform some or all of the transmitting or sending operations described herein as being performed by the network node QQ400. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0201] The power source QQ408 provides power to the various components of network node QQ400 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source QQ408 may further comprise, or be coupled to, power management circuitry to supply the components of the network node QQ400 with power for performing the functionality described herein. For example, the network node QQ400 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source QQ408. As a further example, the power source QQ408 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.

[0202] Embodiments of the network node QQ400 may include additional components beyond those shown in Figure 8 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node QQ400 may include user interface equipment to allow input of information into the networknode QQ400 and to allow output of information from the network node QQ400. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node QQ400.

[0203] Figure 9 is a block diagram illustrating a virtualization environment QQ500 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments QQ500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as an access network node, UE, core network node, or host. Further, in embodiments in which a virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment QQ500 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0204] Applications QQ502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0205] Hardware QQ504 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers QQ506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VM QQ508A and VM QQ508B (which may be collectively referred to as VMs QQ508), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer QQ506 may present a virtual operating platform that appears like networking hardware to one or more of the VMs QQ508.

[0206] The VMs QQ508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by virtualization layer QQ506. Differentembodiments of the instance of a virtual appliance QQ502 may be implemented on one or more of VMs QQ508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0207] In the context of NFV, each of the VMs QQ508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, nonvirtualized machine. Each of the VMs QQ508, and that part of hardware QQ504 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more of the VMs QQ508 on top of the hardware QQ504 and corresponds to an application QQ502.

[0208] Hardware QQ504 may be implemented in a standalone network node with generic or specific components. Hardware QQ504 may implement some functions via virtualization. Alternatively, hardware QQ504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration QQ510, which, among others, oversees lifecycle management of applications QQ502. In some embodiments, hardware QQ504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system QQ512 which may alternatively be used for communication between hardware nodes and radio units.

[0209] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting theobtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0210] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.EMBODIMENTSGroup A Embodiments1. A method performed by a central unit, CU, in a communications network, the method comprising:logging (300) information about L1 / L2 triggered mobility, LTM, -related mobility events in an LTM user equipment, UE, mobility history residing in memory while the UE remains connected to the CU;receiving (310) a LTM-related message for a LTM cell switch relating to the UE and a distributed unit, DU;detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history;based on the detecting of the ping-pong LTM cell switches, generating (330) an information element, IE, indicating that an LTM ping-pong event was detected for the UE; and sending (340) another LTM-related message containing the IE to the DU and / or to another DU.2. The method of Embodiment 1, wherein the logging (300) of information comprises, for each LTM cell switch of the UE adding an entry to a list in the LTM UE mobility history to indicate the LTM cell switch of the UE occurred and a time when the LTM cell switch occurred.3. The method of Embodiment 2, further comprising:deleting an entry in the list in the LTM UE mobility history responsive to the entry having an indicated time when the LTM cell switch occurred that exceeds a threshold time defined as associated with ping-pong LTM cell switches.4. The method of any of Embodiments 1 to 3, wherein the logging (300) of information comprises logging at least one of a source cell identifier, a target cell identifier, or an absolute time of the mobility event for the UE into the LTM UE mobility history.5. The method of any of Embodiments 1 to 4, wherein the receiving (310) of the LTM-related message for the LTM cell switch relating to the UE and the DU, comprises receiving a DU-CU cell switch notification indicating a target cell ID and a Transmission ConfigurationIndicator, TCI, state ID.6. The method of any of Embodiments 1 to 5, wherein the detecting (320) of ping-pong LTM cell switches of the UE between two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:responsive to determining from content of the LTM-related message that a LTM cell switch has been triggered for the UE, determining from a list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell.7. The method of Embodiment 6, wherein the determining from the list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell, comprises:determining that the present LTM cell switch and the previous cell switch of the UE were controlled by different DUs.8. The method of any of Embodiments 1 to 7, wherein the generating (330) of the IE indicating that the LTM ping-pong event was detected for the UE, comprises:generating the IE to include information indicating at least one of:a source cell ID;a target cell ID;an absolute time for the LTM cell switch;a previous source cell type of a previous LTM cell switch of the UE; a previous target cell ID of the previous LTM cell switch of the UE; a previous target cell type of the previous LTM cell switch of the UE; a time duration that the UE spent in a previous cell before a LTM cell switch; and an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.9. The method of any of Embodiments 1 to 8, wherein the generating (330) of the IE indicating that the LTM ping-pong event was detected for the UE, comprises:generating the IE to include information indicating at least one of:an indication that the target DU or the another DU is to operate to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;an indication that the target DU and the another DU are both to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;an indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs; andan indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs.10. The method of any of Embodiments 1 to 9, wherein the sending (340) of the another LTM-related message containing the IE to the DU and / or to another DU, comprises:sending the IE in a CU-DU cell switch notification or a Fl interface application protocol message.11. The method of any of the Embodiments 1 to 10, further comprising:determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:current communication resource load utilization in the DUs;average of the resource load utilization in the DUs;sliding average of number of radio link failure reports and / or successful handover reports of the DUs;sliding average of number of or frequence of radio link failure reports and / or successful handover reports associated with the DUs or cells controlled by the DUs;LTM cell switch failures occurring during ping-pong LTM cell switch sequences involving the DUs;total capacity of the respective cells controlled by the DUs;composite available capacity of the respective cells controlled by the DUs; number of active UEs in the respective cells controlled by the DUs; number of radio resource control, RRC, connections in the respective cells controlled by the DUs;per slice available capacity for network slices in the respective cells controlled by the DUs; andTransport Network Layer, TNL, capacity for the respective cells controlled by the DUs.12. The method of any of the Embodiments 1 to 11, further comprising: determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:Synchronization Signal Block, SSB, Area Radio Resource Status for the SSB areas in the respective cells controlled by the DUs;remaining unused communication resource capacity in the respective cells controlled by the DUs;comparison between the DUs of relative communication resource load of respective cells controlled by the DUs;comparison between the DUs of a ratio of used communication resource capacity and total communication resource capacity of the respective DUs; andcomparison between the DUs of a ratio of unused communication resource capacity and total communication resource capacity of the respective DUs.13. The method of any of the Embodiments 1 to 12, further comprising: determining which of a plurality of DUs controlled by the CU to send the another LTM-related message based on at least one of:number of connected UEs in the respective cells controlled by the DUs; L3 measurements reported by the UE;in which cell of which of the DUs the UE remains when the ping-pong switching is determined to end;which of the DUs involved in ping-pong LTM cell switches with the UE was also involved in a L3 handover; andreported measurement results from other UEs involved in ping-pong LTM cell switches.14. The method of any of the Embodiments 1 to 13, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from a source DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the source DU indicating the cell towards which the DU moved the UE based on a LTM Cell Switch Command.15. The method of any of the Embodiments 1 to 14, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from a target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.16. The method of any of the Embodiments 1 to 15, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from the DU in its roles as target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the DU in its roles as target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.17. The method of any of the Embodiments 1 to 16, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a LTM Cell Switch.18. The method of any of the Embodiments 1 to 17, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong Conditional LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.19. The method of any of the Embodiments 1 to 18, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related message and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, and responsive to the detecting preventing further LTM cell switch of the UE while the a signal quality quantity is above a defined threshold.Group B Embodiments1. A method performed by a distributed unit, DU, in a communications network, the methodcomprising:receiving (400) a L1 / L2 triggered mobility, LTM, -related message containing an information element, IE, indicating that a central unit, CU, detected an LTM ping-pong event characterized by ping-pong LTM cell switches of a UE between at least two cells; and adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE.2. The method of any of Embodiments 1 to 2, wherein the adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, comprises:adapting a measurement configuration parameter and / or a mobility offset parameter used to control present or future LTM cell switch of the UE or other UEs, based on the IE.3. The method of any of Embodiments 1 to 3, further comprising:identifying based on the IE at least one of:a source cell ID;the target cell ID;an absolute time for the LTM cell switch;a previous source cell type of a previous LTM cell switch of the UE; a previous target cell ID of the previous LTM cell switch of the UE; a previous target cell type of the previous LTM cell switch of the UE; a time duration that the UE spent in a previous cell before a LTM cell switch; and an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.4. The method of any of Embodiments 1 to 3, wherein the adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, comprises at least one of:adapting a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;adapting a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs; andadapting a mobility parameter for a channel quality quantity threshold used forLTM cell switching of the UE or other UEs.5. The method of any of Embodiments 1 to 4, wherein the received (400) LTM-related message comprises a CU-DU cell switch notification or a Fl interface application protocol message.6. The method of any of Embodiments 1 to 5, further comprising:sending a response message to the CU indicating that DU has adapted based on the CU indicated detection of the LTM ping-pong event.7. The method of any of Embodiments 1 to 5, further comprising:sending a response message to the CU indicating that DU has not adapted based on the CU indicated detection of the LTM ping-pong event.8. The method of any of Embodiments 1 to 7, further comprising:sending a response message to the CU indicating that another DU is responsible for adapting based on the CU indicated detection of the LTM ping-pong event.9. The method of Embodiment 8, further comprising:sending in the response message to the CU an indication of LTM cell switch mobility change suggestions that the CU can forward to the another DU.10. The method of any of the Embodiments 1 to 9, further comprising:detecting ping-pong LTM cell switches of the UE between at least two cells of the DU based on comparing cell identity of a cell serving the UE before the DU in its role of source DU received a first message indicating that the UE moved away from the cell of the source DU, and a cell identity comprised in the first message or a second message the CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.Group C Embodiments1. A central unit, CU, in a communications network, comprising:processing circuitry configured to perform operations corresponding to the methods of any of the Group A embodiments; anda power source configured to supply power to the processing circuitry.Group D Embodiments1. A distributed unit, DU, in a communications network, comprising:processing circuitry configured to perform operations corresponding to the methods of any of the Group B embodiments; anda power source configured to supply power to the processing circuitry.

[0211] A listing of documents referenced herein follows:

[0212] 1. 3GPP TR 38.811 Study on New Radio (NR) to support non-terrestrial networks (Rel-15)

[0213] 2. 3GPP TR 38.821 Solutions for NR to support non-terrestrial networks (NTN) (Rel-16)

[0214]

[0215] At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).3GPP 3rd Generation Partnership Project5G 5th Generation5GC 5G Core5GS 5G SystemARFCN Absolute Radio Frequency Channel NumberASN.1 Abstract Syntax Notation OneCA Carrier AggregationCE Control ElementCGI Cell Global IdentityCHO Conditional HandoverCN Core NetworkCP Control PlaneCP Cyclic PrefixCPA Conditional PSCell AdditionCP AC Conditional PSCell Addition / ChangeCPC Conditional PSCell ChangeCU Central UnitDAPS Dual Active Protocol StackDC Dual ConnectivityDL DownlinkDU Distributed UniteNB Evolved NodeB (A radio base station in LTE.)EPC Evolved Packet CoreEPS Evolved Packet SystemFl The interface between a CU and a DU in NR.F1AP Fl Application ProtocolGEO Geostationary Earth OrbitgNB A radio base station in NR.GNSS Global Navigation Satellite SystemGSO Geosynchronous OrbitHO HandoverIAB Integrated Access BackhaulIE Information ElementloT Internet of ThingsLI Layer 1L2 Layer 2L3 Layer 3LEO Low Earth OrbitLTE Long Term EvolutionLTM L1 / L2 Triggered MobilityMAC Medium Access ControlMBB Mobile BroadbandMCG Master Cell GroupMEO Medium Earth OrbitmMTC Massive MTCMN Master NodeMRO Mobility Robustness OptimizationMsgB Message BMTC Machine Type CommunicationNB NarrowbandNCGI NR CGI NG Next Generation (Or the interface between the 5G RAN and the 5G core network.) NGAP NG Application Protocol (The protocol used between the NG-RAN and the 5G core network.)NGSO Non-Geosynchronous OrbitNR New RadioNTN Non-Terrestrial NetworkOAM Operation and MaintenancePCell Primary CellPCI Physical Cell IdentityPDCCH Physical Downlink Control ChannelPSCell Primary Secondary CellPUCCH Physical Uplink Control ChannelPUSCH Physical Uplink Shared ChannelRA Random AccessRACH Random Access ChannelRAN Radio Access NetworkRAR Random Access ResponseRLF Radio Link FailureRRC Radio Resource ControlRSRP Reference Signal Received PowerRSRQ Reference Signal Received Quality7SCell Secondary CellSCG Secondary Cell GroupSFN System Frame NumberSI System InformationSIB System Information BlockSHR Successful Handover ReportSN Secondary NodeSON Self-Organizing NetworkSPR Successful PSCell Addition / Change Report (or “Successful PSCell Report”) TA Timing AdvanceTAT Time Alignment TimerTCI Transmission Configuration IndicatorTR Technical ReportTS Technical SpecificationUE User EquipmentUL UplinkUP User PlaneURLLC Ultra-Reliable Low-Latency Communication UTC Coordinated Universal TimeXn The interface between two gNBs.XnAP Xn Application Protocol

Claims

CLAIMS:

1. A method performed by a central unit, CU, in a communications network, the method comprising:logging (300) information about L1 / L2 triggered mobility, LTM, -related mobility events in an LTM user equipment, UE, mobility history residing in memory while the UE remains connected to the CU;receiving (310) LTM-related information for a LTM cell switch relating to the UE and a distributed unit, DU;detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history;based on the detecting of the ping-pong LTM cell switches, generating (330) an information element, IE, indicating that an LTM ping-pong event was detected for the UE; and sending (340) other LTM-related information containing the IE to the DU and / or to another DU.

2. The method of Claim 1, wherein the logging (300) of information comprises, for each LTM cell switch of the UE adding an entry to a list in the LTM UE mobility history to indicate the LTM cell switch of the UE occurred and a time when the LTM cell switch occurred.

3. The method of Claim 2, further comprising:deleting an entry in the list in the LTM UE mobility history responsive to the entry having an indicated time when the LTM cell switch occurred that exceeds a threshold time defined as associated with ping-pong LTM cell switches.

4. The method of any of Claims 1 to 3, wherein the logging (300) of information comprises logging at least one of a source cell identifier, a target cell identifier, or an absolute time of the mobility event for the UE into the LTM UE mobility history.

5. The method of any of Claims 1 to 4, wherein the receiving (310) of the LTM-related information for the LTM cell switch relating to the UE and the DU, comprises receiving a DU-CU cell switch notification indicating a target cell ID and a Transmission ConfigurationIndicator, TCI, state ID.

6. The method of any of Claims 1 to 5, wherein the detecting (320) of ping-pong LTM cell switches of the UE between two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:responsive to determining from content of the LTM-related information that a LTM cell switch has been triggered for the UE, determining from a list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell.

7. The method of Claim 6, wherein the determining from the list of LTM cell switches for the UE contained in the LTM UE mobility history that the UE completed a previous LTM cell switch from one cell to another cell, comprises:determining that the present LTM cell switch and the previous cell switch of the UE were controlled by different DUs.

8. The method of any of Claims 1 to 7, wherein the generating (330) of the IE indicating that the LTM ping-pong event was detected for the UE, comprises:generating the IE to include information indicating at least one of:a source cell ID;a target cell ID;an absolute time for the LTM cell switch;a previous source cell type of a previous LTM cell switch of the UE; a previous target cell ID of the previous LTM cell switch of the UE; a previous target cell type of the previous LTM cell switch of the UE; a time duration that the UE spent in a previous cell before a LTM cell switch; and an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.

9. The method of any of Claims 1 to 8, wherein the generating (330) of the IE indicating that the LTM ping-pong event was detected for the UE, comprises:generating the IE to include information indicating at least one of:an indication that the target DU or the another DU is to operate to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;an indication that the target DU and the another DU are both to adapt a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;an indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs;an indication that the target DU or the another DU is to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs; andan indication that the target DU and the another DU are both to operate to adapt a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs.

10. The method of any of Claims 1 to 9, wherein the sending (340) of the other LTM-related information containing the IE to the DU and / or to another DU, comprises:sending the IE in a CU-DU cell switch notification or a Fl interface application protocol message.

11. The method of any of the Claims 1 to 10, further comprising:determining which of a plurality of DUs controlled by the CU to send the other LTM-related information based on at least one of:current communication resource load utilization in the DUs;average of the resource load utilization in the DUs;sliding average of number of radio link failure reports and / or successful handover reports of the DUs;sliding average of number of or frequence of radio link failure reports and / or successful handover reports associated with the DUs or cells controlled by the DUs;LTM cell switch failures occurring during ping-pong LTM cell switch sequences involving the DUs;total capacity of the respective cells controlled by the DUs;composite available capacity of the respective cells controlled by the DUs; number of active UEs in the respective cells controlled by the DUs; number of radio resource control, RRC, connections in the respective cells controlled by the DUs;per slice available capacity for network slices in the respective cells controlled by the DUs; andTransport Network Layer, TNL, capacity for the respective cells controlled by the DUs.

12. The method of any of the Claims 1 to 11, further comprising:determining which of a plurality of DUs controlled by the CU to send the other LTM-related information based on at least one of:Synchronization Signal Block, SSB, Area Radio Resource Status for the SSB areas in the respective cells controlled by the DUs;remaining unused communication resource capacity in the respective cells controlled by the DUs;comparison between the DUs of relative communication resource load of respective cells controlled by the DUs;comparison between the DUs of a ratio of used communication resource capacity and total communication resource capacity of the respective DUs; andcomparison between the DUs of a ratio of unused communication resource capacity and total communication resource capacity of the respective DUs.

13. The method of any of the Claims 1 to 12, further comprising:determining which of a plurality of DUs controlled by the CU to send the other LTM-related information based on at least one of:number of connected UEs in the respective cells controlled by the DUs; L3 measurements reported by the UE;in which cell of which of the DUs the UE remains when the ping-pong switching is determined to end;which of the DUs involved in ping-pong LTM cell switches with the UE was also involved in a L3 handover; andreported measurement results from other UEs involved in ping-pong LTM cell switches.

14. The method of any of the Claims 1 to 13, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from a source DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the source DU indicating the cell towards which the DU moved the UE based on a LTM Cell Switch Command.

15. The method of any of the Claims 1 to 14, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from a target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

16. The method of any of the Claims 1 to 15, wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:comparing cell identity of a cell serving the UE before the CU received from the DU in its roles as target DU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the CU received from the DU in its roles as target DU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

17. The method of any of the Claims 1 to 16, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a LTM Cell Switch.

18. The method of any of the Claims 1 to 17, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong Conditional LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, based on comparing cell identity of a cell serving the UE before the first CU received from the second CU a first message indicating that the UE moved to another cell, and a cell identity comprised in the first message or a second message the first CU received from the second CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

19. The method of any of the Claims 1 to 18, wherein the CU is a first CU, and wherein the detecting (320) ping-pong LTM cell switches of the UE between at least two cells based on content of the LTM-related information and information about the LTM-related mobility events of the UE in the LTM UE mobility history, comprises:detecting ping-pong LTM cell switches of the UE between a first cell controlled by the first CU and a second cell controlled by a second CU, and responsive to the detecting preventing further LTM cell switch of the UE while the a signal quality quantity is above a defined threshold.

20. A method performed by a distributed unit, DU, in a communications network, the method comprising:receiving (400) a L1 / L2 triggered mobility, LTM, -related message containing an information element, IE, indicating that a central unit, CU, detected an LTM ping-pong event characterized by ping-pong LTM cell switches of a UE between at least two cells; and adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE.

21. The method of Claim 20, wherein the adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, comprises: adapting a measurement configuration parameter and / or a mobility offset parameter used to control present or future LTM cell switch of the UE or other UEs, based on the IE.

22. The method of any of Claims 20 to 21, further comprising:identifying based on the IE at least one of:a source cell ID;the target cell ID;an absolute time for the LTM cell switch;a previous source cell type of a previous LTM cell switch of the UE; a previous target cell ID of the previous LTM cell switch of the UE; a previous target cell type of the previous LTM cell switch of the UE; a time duration that the UE spent in a previous cell before a LTM cell switch; and an average time duration that a plurality of UEs spend in the previous cell before LTM cell switch.

23. The method of any of Claims 20 to 22, wherein the adapting (410) mobility parameters used to control a present or future LTM cell switch of the UE or other UEs, based on the IE, comprises at least one of:adapting a mobility parameter to increase hysteresis for LTM cell switching of the UE or other UEs;adapting a mobility parameter for a channel quality quantity offset used for LTM cell switching of the UE or other UEs; andadapting a mobility parameter for a channel quality quantity threshold used for LTM cell switching of the UE or other UEs.

24. The method of any of Claims 20 to 23, wherein the received (400) LTM-related information comprises a CU-DU cell switch notification or a Fl interface application protocol message.

25. The method of any of Claims 20 to 24, further comprising:sending a response message to the CU indicating that DU has adapted based on the CU indicated detection of the LTM ping-pong event.

26. The method of any of Claims 20 to 25, further comprising:sending a response message to the CU indicating that DU has not adapted based on the CU indicated detection of the LTM ping-pong event.

27. The method of any of Claims 20 to 26, further comprising:sending a response message to the CU indicating that another DU is responsible for adapting based on the CU indicated detection of the LTM ping-pong event.

28. The method of Claim 27, further comprising:sending in the response message to the CU an indication of LTM cell switch mobility change suggestions that the CU can forward to the another DU.

29. The method of any of the Claims 20 to 28, further comprising:detecting ping-pong LTM cell switches of the UE between at least two cells of the DU based on comparing cell identity of a cell serving the UE before the DU in its role of source DU received a first message indicating that the UE moved away from the cell of the source DU, and a cell identity comprised in the first message or a second message the CU indicating the cell towards which the UE moved based on a Conditional LTM Cell Switch.

30. A central unit, CU, in a communications network, comprising:processing circuitry configured to perform operations corresponding to the methods of any of the Claims 1 to 19; anda power source configured to supply power to the processing circuitry.

31. A distributed unit, DU, in a communications network, comprising:processing circuitry configured to perform operations corresponding to the methods of any of the Claims 20 to 29; anda power source configured to supply power to the processing circuitry.

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