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WO2025073342A1 - Monitoring efficiency of mobility procedure - Google Patents

Monitoring efficiency of mobility procedure Download PDF

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Publication number
WO2025073342A1
WO2025073342A1 PCT/EP2023/077219 EP2023077219W WO2025073342A1 WO 2025073342 A1 WO2025073342 A1 WO 2025073342A1 EP 2023077219 W EP2023077219 W EP 2023077219W WO 2025073342 A1 WO2025073342 A1 WO 2025073342A1
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WO
WIPO (PCT)
Prior art keywords
primary secondary
secondary cell
report
criteria
pscell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/EP2023/077219
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French (fr)
Inventor
Bernhard Wegmann
Martin Kollár
Ahmad AWADA
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Nokia Technologies Oy
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Nokia Technologies Oy
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Publication date
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Priority to PCT/EP2023/077219 priority Critical patent/WO2025073342A1/en
Publication of WO2025073342A1 publication Critical patent/WO2025073342A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00833—Handover statistics
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/34—Reselection control
    • H04W36/36—Reselection control by user or terminal equipment
    • H04W36/362—Conditional handover
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/15—Setup of multiple wireless link connections

Definitions

  • MONITORING EFFICIENCY OF MOBILITY PROCEDURE FIELD [0001] ⁇ The following example embodiments relate to wireless communication. BACKGROUND [0002] ⁇ In wireless communication, a suboptimal mobility procedure may result in network resources to be wasted unnecessarily. As resources are limited, it is desirable to optimize the usage of network resources. BRIEF DESCRIPTION [0003] ⁇ The scope of protection sought for various example embodiments is set out by the claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the claims are to be interpreted as examples useful for understanding various embodiments.
  • a method comprising: receiving, by an apparatus, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing, by the apparatus, a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing, by the apparatus, a result of the measurement with the one or more criteria; and transmitting, by the apparatus, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes.
  • a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes.
  • a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes.
  • a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes.
  • an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receive a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
  • an apparatus comprising: means for transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and means for receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
  • a method comprising: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
  • a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
  • a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
  • FIG. 3 illustrates a scenario, where a user equipment is passing several primary secondary cells;
  • FIG.4 illustrates a signal flow diagram;
  • FIG.5 illustrates a signal flow diagram;
  • FIG.6 illustrates a signal flow diagram;
  • FIG.7 illustrates a signal flow diagram;
  • FIG.8 illustrates a signal flow diagram;
  • FIG.9 illustrates a flow chart;
  • FIG.10 illustrates a flow chart;
  • FIG.11 illustrates an example of an apparatus;
  • FIG.12 illustrates an example of an apparatus.
  • DETAILED DESCRIPTION [0017] ⁇ The following embodiments are exemplifying.
  • a wireless communication network comprising a radio access network based on one or more of the following radio access technologies (RATs): Global System for Mobile Communications (GSM) or any other second generation radio access technology, Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband- code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, fourth generation (4G), fifth generation (5G), 5G new radio (NR), 5G-Advanced (i.e., 3GPP NR Rel-18 and beyond), or sixth generation (6G).
  • RATs radio access technologies
  • GSM Global System for Mobile Communications
  • UMTS Universal Mobile Telecommunication System
  • 3G Universal Mobile Telecommunication System
  • W-CDMA basic wideband- code division multiple access
  • HSPA high-speed packet access
  • LTE Long Term Evolution
  • LTE-Advanced Long Term Evolution-Advanced
  • fourth generation (4G) fifth generation
  • 5G new radio (NR) i.e., 3
  • radio access networks include the universal mobile telecommunications system (UMTS) radio access network (UTRAN), the Evolved Universal Terrestrial Radio Access network (E-UTRA), or the next generation radio access network (NG-RAN).
  • UMTS universal mobile telecommunications system
  • E-UTRA Evolved Universal Terrestrial Radio Access network
  • NG-RAN next generation radio access network
  • the wireless communication network may further comprise a core network, and some example embodiments may also be applied to network functions of the core network. [0019] ⁇ It should be noted that the embodiments are not restricted to the wireless communication network given as an example, but a person skilled in the art may also apply the solution to other wireless communication networks or systems provided with necessary properties. For example, some example embodiments may also be applied to a communication system based on IEEE 802.11 specifications, or a communication system based on IEEE 802.15 specifications.
  • FIG. 1 depicts an example of a simplified wireless communication network showing some physical and logical entities.
  • the connections shown in FIG.1 may be physical connections or logical connections. It is apparent to a person skilled in the art that the wireless communication network may also comprise other physical and logical entities than those shown in FIG.1.
  • the example embodiments described herein are not, however, restricted to the wireless communication network given as an example but a person skilled in the art may apply the embodiments described herein to other wireless communication networks provided with necessary properties.
  • the example wireless communication network shown in FIG. 1 includes an access network, such as a radio access network (RAN), and a core network 110.
  • RAN radio access network
  • the AN 104 may be an evolved NodeB (abbreviated as eNB or eNodeB), or a next generation evolved NodeB (abbreviated as ng-eNB), or a next generation NodeB (abbreviated as gNB or gNodeB), providing the radio cell.
  • eNB evolved NodeB
  • ng-eNB next generation evolved NodeB
  • gNB next generation NodeB
  • the wireless connection (e.g., radio link) from a UE to the access node 104 may be called uplink (UL) or reverse link, and the wireless connection (e.g., radio link) from the access node to the UE may be called downlink (DL) or forward link.
  • UE 100 may also communicate directly with UE 102, and vice versa, via a wireless connection generally referred to as a sidelink (SL).
  • SL sidelink
  • the access node 104 or its functionalities may be implemented by using any node, host, server or access point etc. entity suitable for providing such functionalities.
  • the access network may comprise more than one access node, in which case the access nodes may also be configured to communicate with one another over links, wired or wireless.
  • the access node may comprise a computing device configured to control the radio resources of the access node.
  • the access node may also be referred to as a base station, a base transceiver station (BTS), an access point, a cell site, a radio access node or any other type of node capable of being in a wireless connection with a UE (e.g., UEs 100, 102).
  • the access node may include or be coupled to transceivers. From the transceivers of the access node, a connection may be provided to an antenna unit that establishes bi-directional radio links to UEs 100, 102.
  • the antenna unit may comprise an antenna or antenna element, or a plurality of antennas or antenna elements.
  • the access node 104 may further be connected to a core network (CN) 110.
  • the core network 110 may comprise an evolved packet core (EPC) network and/or a 5 th generation core network (5GC).
  • the EPC may comprise network entities, such as a serving gateway (S-GW for routing and forwarding data packets), a packet data network gateway (P-GW) for providing connectivity of UEs to external packet data networks, and a mobility management entity (MME).
  • S-GW serving gateway
  • P-GW packet data network gateway
  • MME mobility management entity
  • the 5GC may comprise one or more network functions, such as at least one of: a user plane function (UPF), an access and mobility management function (AMF), a location management function (LMF), and/or a session management function (SMF).
  • the core network 110 may also be able to communicate with one or more external networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them.
  • the UPF of the core network 110 may be configured to communicate with an external data network via an N6 interface.
  • the P-GW of the core network 110 may be configured to communicate with an external data network.
  • the illustrated UE 100, 102 is one type of an apparatus to which resources on the air interface may be allocated and assigned.
  • the UE 100, 102 may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device just to mention but a few names.
  • the UE may be a computing device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of computing devices: a mobile phone, a smartphone, a personal digital assistant (PDA), a handset, a computing device comprising a wireless modem (e.g., an alarm or measurement device, etc.), a laptop computer, a desktop computer, a tablet, a game console, a notebook, a multimedia device, a reduced capability (RedCap) device, a wearable device (e.g., a watch, earphones or eyeglasses) with radio parts, a sensor comprising a wireless modem, or any computing device comprising a wireless modem integrated in a vehicle.
  • SIM subscriber identification module
  • a UE may also be a nearly exclusive uplink-only device, of which an example may be a camera or video camera loading images or video clips to a network.
  • a UE may also be a device having capability to operate in an Internet of Things (IoT) network, which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction.
  • IoT Internet of Things
  • the UE may also utilize cloud. In some applications, the computation may be carried out in the cloud or in another UE.
  • 5G enables using multiple input – multiple output (MIMO) antennas in the access node 104 and/or the UE 100, 102, many more base stations or access nodes than an LTE network (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available.
  • 5G wireless communication networks may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, such as (massive) machine- type communications (mMTC), including vehicular safety, different sensors and real- time control.
  • MIMO multiple input – multiple output
  • access nodes and/or UEs may have multiple radio interfaces, namely below 6GHz, cmWave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, for example, as a system, where macro coverage may be provided by the LTE, and 5G radio interface access may come from small cells by aggregation to the LTE.
  • a 5G wireless communication network may support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6GHz – cmWave – mmWave).
  • One of the concepts considered to be used in 5G wireless communication networks may be network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the substantially same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.
  • an access node may comprise: a radio unit (RU) comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105 that may be used for the so-called Layer 1 (L1) processing and real-time Layer 2 (L2) processing; and a central unit (CU) 108 (also known as a centralized unit) that may be used for non- real-time L2 and Layer 3 (L3) processing.
  • the CU 108 may be connected to the one or more DUs 105 for example via an F1 interface.
  • the access node may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites.
  • the CU and DU together may also be referred to as baseband or a baseband unit (BBU).
  • the CU and DU may also be comprised in a radio access point (RAP).
  • RAP radio access point
  • the CU 108 may be a logical node hosting radio resource control (RRC), service data adaptation protocol (SDAP) and/or packet data convergence protocol (PDCP), of the NR protocol stack for an access node.
  • RRC radio resource control
  • SDAP service data adaptation protocol
  • PDCP packet data convergence protocol
  • the DU 105 may be a logical node hosting radio link control (RLC), medium access control (MAC) and/or physical (PHY) layers of the NR protocol stack for the access node.
  • the operations of the DU may be at least partly controlled by the CU. It should also be understood that the distribution of functions between DU 105 and CU 108 may vary depending on implementation.
  • the CU may comprise a control plane (CU-CP), which may be a logical node hosting the RRC and the control plane part of the PDCP protocol of the NR protocol stack for the access node.
  • the CU may further comprise a user plane (CU-UP), which may be a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node.
  • CU-CP control plane
  • CU-UP user plane
  • a Cloud computing systems may also be used to provide the CU 108 and/or DU 105.
  • a CU provided by a cloud computing system may be referred to as a virtualized CU (vCU).
  • vCU virtualized CU
  • vDU virtualized DU
  • the DU may be implemented on so-called bare metal solutions, for example application-specific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC).
  • ASIC application-specific integrated circuit
  • CSSP customer-specific standard product
  • SoC system-on-a-chip
  • ⁇ Edge cloud may be brought into the access network (e.g., RAN) by utilizing network function virtualization (NFV) and software defined networking (SDN).
  • NFV network function virtualization
  • SDN software defined networking
  • edge cloud may mean access node operations to be carried out, at least partly, in a computing system operationally coupled to a remote radio head (RRH) or a radio unit (RU) of an access node. It is also possible that access node operations may be performed on a distributed computing system or a cloud computing system located at the access node.
  • RRH remote radio head
  • RU radio unit
  • access node operations may be performed on a distributed computing system or a cloud computing system located at the access node.
  • Application of cloud RAN architecture enables RAN real-time functions being carried out at the access network (e.g., in a DU 105) and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108).
  • a 5G wireless communication network (“5G network”) may also comprise a non-terrestrial communication network, such as a satellite communication network, to enhance or complement the coverage of the 5G radio access network.
  • a non-terrestrial communication network such as a satellite communication network
  • satellite communication may support the transfer of data between the 5G radio access network and the core network, enabling more extensive network coverage.
  • Possible use cases may be providing service continuity for machine-to- machine (M2M) or Internet of Things (IoT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications.
  • M2M machine-to- machine
  • IoT Internet of Things
  • Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed).
  • GEO geostationary earth orbit
  • LEO low earth orbit
  • a given satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells.
  • the on- ground cells may be created through an on-ground relay access node or by an access node 104 located on-ground or in a satellite.
  • the access node 104 depicted in FIG.1 is just an example of a part of an access network (e.g., a radio access network) and in practice, the access network may comprise a plurality of access nodes, the UEs 100, 102 may have access to a plurality of radio cells, and the access network may also comprise other apparatuses, such as physical layer relay access nodes or other entities. At least one of the access nodes may be a Home eNodeB or a Home gNodeB.
  • a Home gNodeB or a Home eNodeB is a type of access node that may be used to provide indoor coverage inside a home, office, or other indoor environment.
  • Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells.
  • the access node(s) of FIG. 1 may provide any kind of these cells.
  • a cellular radio network may be implemented as a multilayer access networks including several kinds of radio cells. In multilayer access networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be needed to provide such a multilayer access network.
  • An access network which may be able to use “plug-and-play” access nodes, may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway, or HNB-GW (not shown in FIG.1).
  • An HNB-GW which may be installed within an operator’s access network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network of the operator.
  • FIG.2 illustrates an example of a wireless communication system, to which some example embodiments may be applied.
  • Dual connectivity enables a UE 100 to be simultaneously connected to two cell groups: a master cell group (MCG) 210 and a secondary cell group (SCG) 220.
  • MCG master cell group
  • SCG secondary cell group
  • the two cell groups 210, 220 may be associated with different access nodes 104A, 104B.
  • the two cell groups 210, 220 may be based on different radio access technologies (e.g., LTE and 5G), or they may both be based on the same radio access technology (e.g., 5G).
  • the term “cell” refers to a radio cell.
  • the MCG 210 is a group of serving cells controlled by the master node (MN) 104A.
  • the master node 104A is a RAN node providing the control plane connection to the core network 110.
  • the MCG 210 comprises a primary cell (PCell) 211, i.e., the primary serving cell of the MCG 210, and optionally one or more secondary cells (SCells) 212.
  • the PCell 211 is a cell operating on a primary frequency that may be used for initial access under the MCG 210.
  • An SCell is a cell, operating on a secondary frequency, which may be configured once an RRC connection is established, and which may be used to provide additional radio resources.
  • the SCG 220 is a group of serving cells controlled by the secondary node (SN) 104B.
  • the secondary node 104B is a RAN node providing additional resources to the UE 100.
  • the SCG 220 comprises a primary secondary cell (PSCell) 221, i.e., the primary serving cell of the SCG 220, and optionally one or more SCells 222.
  • the PSCell 221 is a cell that may be used for initial access under the SCG 220.
  • CPC conditional primary secondary cell change
  • CPC has been extended for inter-SN scenarios (i.e., changing to a target PSCell controlled by a different SN than the SN that controls the source PSCell) with MN-initiated CPC and SN-initiated CPC.
  • the procedure of changing the linkage to different SN is to be carried out by the MN.
  • the SN starts the process with a request message, if the UE 100 is reporting via SRB3 to the SN.
  • the signaling associated with SN-initiated inter-SN CPC is described in the following.
  • the source SN indicates to the MN the identifiers (IDs) of the target SNs that shall be contacted for preparing as candidate target PSCell(s) for CPC.
  • the source SN suggests a list of PSCell(s) to be prepared by each target SN and provides a CPC execution condition for each suggested target PSCell.
  • the CPC execution conditions are not forwarded to the target SNs, but are sent with a configuration message to the UE by the MN.
  • the source SN indicates the maximum number of PSCells that can be prepared by each target SN, i.e., the actual number of prepared cells can be equal to or lower than the maximum of the list of suggested PSCells.
  • the MN sends an Addition Request message to each target SN indicated by the source SN.
  • the Addition Request includes the list of PSCells that are suggested by the source SN along with the maximum number of PSCells that can be prepared.
  • the target SN decides on the candidate target PSCell(s) to be prepared among the suggested list. The target SN cannot select a PSCell that is not included in the list.
  • the target SN sends to the MN the CPC configuration for each prepared target PSCell and the ID(s) of the prepared target PSCell(s).
  • the UE sends a message to the MN indicating the execution of the CPC configuration.
  • the message includes an embedded SN RRC Reconfiguration Complete to the target SN 1, which is sent by the MN to the target SN 1.
  • the UE then completes the random access to the new target PSCell.
  • the signaling for MN-initiated inter-SN CPC is similar to the SN- initiated inter-SN CPC described above, except that the first step is not needed.
  • the MN In MN- initiated CPC, the MN provides in the SN Addition Request the list of PSCells that are suggested to be prepared by the target SN along with the maximum number of PSCells that can be prepared by the target SN. Moreover, the MN configures the UE with the CPAC execution conditions for the prepared PSCells.
  • SA selective activation
  • the selective activation of cell groups should support an early preparation of future subsequent CPCs, and the initial focus of Release 18 is on SCG by applying in advance configurations to reduce the signaling overhead. However, the selective activation of cell group is foreseen to be applicable also to the case when the cell group is MCG (and SCG).
  • the UE may keep the conditional handover configurations after executing a handover and just activates those for further cell changes.
  • SA will not release the prepared potential candidate PSCells, which might also be candidates from the perspective of the new source PSCell after the PSCell change completion. Furthermore, the UE does not release the conditional configuration of other candidate PSCells for subsequent CPCs, provided that they are applicable with respect to the new reference source PSCell.
  • SA may result in benefits in terms of signaling overhead reduction for fast PSCell changes in immediate succession due to small cells and a certain anticipation of the UE movement.
  • FIG. 3 illustrates a scenario, where the UE 100 is passing several PSCells 221A, 221B, 221C, 221D. [0063] ⁇
  • the UE 100 moves along the trajectory indicated by the black arrow, and the UE is changing from single-connectivity at point 301 to dual- connectivity at point 302 by means of conditional primary secondary cell addition (CPA), for instance.
  • CPC conditional primary secondary cell addition
  • the cell changes are analyzed with respect to the two mobility procedures (i.e., CPC and SA).
  • an A3 Event can be used for CPC or SA preparation triggered by the second PSCell 221B and strong measurements of the third PSCell 221C and the fourth PSCell 221D.
  • the MN 104A sends, for the preparation of the second PSCell 221B, the third PSCell 221C, and the fourth PSCell 221D as potential candidate target cells, a SN ADDITION REQUEST message to the target SN(s) serving these PSCells 221B, 221C, 221D.
  • the MN 104A receives, for each target PSCell 221B, 221C, 221D, all the needed information to access the cell, such as the cell radio network temporary identifier (C-RNTI), security algorithm identifiers, and a dedicated random-access channel (RACH) preamble for contention-free random access (CFRA).
  • C-RNTI cell radio network temporary identifier
  • RACH dedicated random-access channel
  • the SN ADDITION REQEST message from the MN 104A to the target SN(s) may include information about the other target candidate cells being prepared in parallel, so that the required conditional configuration (condConfig) measurement settings can be provided to configure the UE 100 in advance.
  • condConfig required conditional configuration
  • the MN 104A configures the UE 100 with an RRC Reconfiguration with a synchronization message that includes the condConfig parameters for the three envisaged target PSCells 221B, 221C, 221D.
  • the UE 100 may be configured with the following condCofig parameters: A3(P1->P2), A3(P1->P3), A3(P1->P4).
  • A3(P1->P2) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the second PSCell 221B.
  • ⁇ A3(P1->P3) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the third PSCell 221C.
  • ⁇ A3(P1->P4) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the fourth PSCell 221D.
  • the UE 100 may be configured with further condConfig parameters, which may be provided with the SN ADDITION REQ ACK from the target SN(s) to the MN 104A: from the second PSCell 221B: A3(P2->P1), A3(P2->P3), A3(P2- >P4); from the third PSCell 221C: A3(P3->P1), A3(P3->P2), A3(P3->P4); and from the fourth PSCell 221D: A3(P4->P1), A3(P4->P2), A3(P4->P3).
  • these further condConfig parameters may be marked as deactivated as long as the UE 100 is connected to the first PSCell 221A.
  • ⁇ A3(P2->P1) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the first PSCell 221A.
  • ⁇ A3(P2->P3) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the third PSCell 221C.
  • ⁇ A3(P2->P4) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the fourth PSCell 221D.
  • ⁇ A3(P3->P1) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the first PSCell 221A.
  • ⁇ A3(P3->P2) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the second PSCell 221B.
  • ⁇ A3(P3->P4) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the fourth PSCell 221D.
  • ⁇ A3(P4->P1) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the first PSCell 221A.
  • ⁇ A3(P4->P2) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the second PSCell 221B.
  • ⁇ A3(P4->P3) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the third PSCell 221C.
  • condConfig A3(P1->P4) triggers synchronization (i.e., random access) at the UE 100 with the fourth PSCell 221D (i.e., the UE 100 autonomously executes a handover).
  • the preparations of the second PSCell 221B and the third PSCell 221C remain, and the first PSCell 221A will be prepared as a candidate target PSCell.
  • the UE 100 activates the condConfig for the fourth PSCell 221D: A3(P4->P1), A3(P4->P2), A3(P4- >P3) for the conditional autonomous handover execution, while deactivating the former conditional execution criterion for the first PSCell 221A.
  • An advantage of keeping the preparations is that immediate UE-autonomous handover execution is possible for fast subsequent cell changes.
  • the MN 104A sends, for the preparation of the second PSCell 221B and the third PSCell 221C as potential candidate target cells, an SN ADDITION REQUEST message to the target SN(s) serving these PSCells 221B, 221C.
  • an SN ADDITION REQUEST ACK message from the target SN(s)
  • the MN 104A receives, for each target cell, all the needed information to access the cell, such as C- RNTI, security algorithm identifiers, and a dedicated RACH preamble for CFRA.
  • the MN 104A configures the UE 100 with an RRC Reconfiguration with a synchronization message that includes the condConfig parameters for the two envisaged target cells 221B, 221C, i.e., A3(P4->P2), A3(P4->P3). [0086] ⁇
  • condConfig A3(P4->P3) triggers synchronization (random access) at the UE 100 with the third PSCell 221C (i.e., handover execution).
  • the UE’s secondary link may now remain for a while.
  • the UE 100 activates another condConfig setting for the third PSCell 221C: A3(P3->P1), A3(P3->P2), A3(P3->P4) for CPC execution.
  • the former one for the fourth PSCell 221D is deactivated. If the UE 100 stays in the third PSCell 221C for a while, the long-term blocking of the network resources needed for the autonomous handover execution to an arbitrary neighbor cell is somewhat too excessive. [0089] ⁇ At point 307 (only needed for CPC, since the fourth PSCell 221D is prepared for SA), for instance, an A3 Event for CPC preparation is triggered by the fourth PSCell 221D, while all other neighbor cells are rather weak.
  • the MN 104A sends an SN ADDITION REQUEST message to the target SN(s) serving the fourth PSCell 221D.
  • the MN 104A receives, for that target cell, all the needed information to access the cell, such as C- RNTI, security algorithm identifiers, and a dedicated RACH preamble for CFRA.
  • CPC requires more signaling compared to SA in terms of UE measurement reports, inter-node signaling for the preparation (e.g., SN ADDITION REQUEST, etc.), and the RRC Reconfiguration message to the UE, as well as the SN RELEASE REQUEST messages after successful handover execution.
  • the network resource blockage is reduced with CPC compared to SA. For example, with SA, between points 306 and 308, the resources for all cells 221A, 221B, 221C, 221D (including the second PSCell 221B, which is never used), are blocked for quite a while.
  • Some example embodiments provide such a method for monitoring the efficiency of the applied mobility procedure (e.g., CPC or SA) for PSCell changes of a UE using dual connectivity.
  • Some example embodiments may utilize one or more new measurement criteria, which trigger information reporting for example to a RAN-based self-organizing network (SON) instance, which in turn uses this information to optimize the network such that each cell or cell group is configured with the best- performing and most efficient mobility procedure.
  • the new measurement criteria allow to determine which mobility procedure (e.g., CPC or selective activation) is optimal for a specific cell border (e.g., between PSCells 221A and 221B of FIG.
  • one new criterion may be applied to UEs configured for the CPC procedure. This criterion relates to the measured time between at least two consecutive (CPC-based) PSCell changes, and this criterion may trigger logging of specific information, if the measured time is shorter than a first threshold (e.g., called “threshold_min_consecutive_CPC”). This logged information may be reported to a network entity (e.g., hosting a SON instance).
  • a first threshold e.g., called “threshold_min_consecutive_CPC”.
  • a counter may be incremented, wherein this counter expresses that the two consecutive CPC-based cell changes are “tight in succession”, which indicates that SA may be more optimal compared to CPC.
  • Another criterion may be applied to UEs configured for the SA procedure. This criterion relates to the measured time between two consecutive (SA- based) PSCell changes, and this criterion would trigger logging of specific information, if the measured time is longer than a second threshold (e.g., called “threshold_max_consecutive_SA”). This logged information may be reported to a network entity (e.g., hosting a SON instance).
  • a counter is incremented, wherein this counter expresses that the two consecutive SA-based cell changes are “widely spaced SA”, which indicates that SA may waste network resources and CPC would be more optimal, since time for preparation is not an issue in this case.
  • the counters may be statistically analyzed and used to update the PSCell-related mobility configuration responsible for the UE mobility configuration (e.g., by means of an RRC Reconfiguration procedure). Thus, after a while, each cell pair or even cell group may reach the optimal mobility configuration.
  • 5G radio access technology without limiting the example embodiments to 5G radio access technology, however.
  • FIG. 4 illustrates a signal flow diagram according to an example embodiment.
  • a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration message) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100.
  • the UE 100 receives the configuration.
  • the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria.
  • the UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode.
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes.
  • the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization.
  • the first threshold e.g., called “threshold_min_consecutive_CPC”
  • the first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold.
  • the second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA.
  • the second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold.
  • the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure.
  • the UE 100 may start a timer upon handover completion to the current serving cell (e.g., PSCell 221A), and monitor the time until the next CPC or SA execution to a new PSCell (e.g., PSCell 221B). [0107] ⁇ At 403, the UE 100 compares a result of the measurement with the one or more criteria. [0108] ⁇ At 404, the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The master node 104A receives the message.
  • the current serving cell e.g., PSCell 221A
  • a new PSCell e.g., PSCell 221B
  • the UE 100 compares a result of the measurement with the one or more criteria.
  • the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated
  • the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 401).
  • the report may comprise a new report type called a mobility method optimization (MMO) report.
  • the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO.
  • SHR successful handover report
  • SPR successful PSCell change report
  • the report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇ ), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell.
  • a cause of the at least two consecutive PSCell changes e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇
  • a time stayed e.g., indicated as an integer between 1 and 1023
  • the integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA).
  • the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM ⁇ CPC ⁇ or ENUM ⁇ SA ⁇ ).
  • the information may indicate the mobility procedure explicitly or implicitly.
  • the cause ENUM may implicitly indicate the mobility procedure.
  • the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent (SA-based) cell changes after the at least two consecutive PSCell changes, i.e., the number of further already configured hops (the final SON decision may use this information when considering a series of PSCell changes).
  • a network entity 111 such as a network management system (NMS).
  • NMS network management system
  • the network entity 111 may host a self-organizing network (SON) function.
  • SON self-organizing network
  • the network entity 111 increments at least one counter based on the report.
  • a corresponding counter e.g., called “too tight consecutive CPSs”
  • a corresponding counter e.g., called “Too widely spaced SAs”
  • the network entity 111 determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. [0119] ⁇ At 408, based on determining to change the mobility procedure, the network entity 111 transmits, to the master node 104A, an indication for changing the mobility procedure applied by the UE 100 for the cell border. The master node 104A receives the indication. [0120] ⁇ At 409, based on receiving the indication from the network entity 111, the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100.
  • the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa.
  • the master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure.
  • FIG. 5 illustrates a signal flow diagram according to an example embodiment for MN-initiated reporting with a distributed SON.
  • a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100.
  • the UE 100 receives the configuration.
  • the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria.
  • a new information element e.g., called “MMO-Monitor-Config”
  • a “SuccessHO-Config” information element may include the one or more criteria.
  • the UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode.
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes.
  • the second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold.
  • the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell.
  • the UE 100 compares a result of the measurement with the one or more criteria.
  • the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100.
  • the master node 104A receives the message.
  • the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 501).
  • the report may comprise a new report type called a mobility method optimization (MMO) report.
  • the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO.
  • SHR successful handover report
  • SPR successful PSCell change report
  • the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison.
  • the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison.
  • the integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time.
  • the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM ⁇ CPC ⁇ or ENUM ⁇ SA ⁇ ).
  • the information may indicate the mobility procedure explicitly or implicitly.
  • the cause ENUM may implicitly indicate the mobility procedure.
  • the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes).
  • the master node 104A increments at least one counter based on the report. In other words, the master node 104A creates and analyzes counter statistics per PSCell border.
  • the master node 104A may host a self-organizing network (SON) function.
  • SON self-organizing network
  • a corresponding counter e.g., called “too tight consecutive CPSs”
  • a corresponding counter e.g., called “Too widely spaced SAs”
  • the master node 104A determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes.
  • the determination may be based on analyzing the counter statistics for the cell border.
  • the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100.
  • the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa.
  • the master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure.
  • FIG. 6 illustrates a signal flow diagram according to an example embodiment for MN-initiated reporting with a centralized SON.
  • a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100.
  • the UE 100 receives the configuration.
  • the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria.
  • MMO-Monitor-Config e.g., called “MMO-Monitor-Config”
  • a “SuccessHO-Config” information element may include the one or more criteria.
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes.
  • the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization.
  • the first threshold e.g., called “threshold_min_consecutive_CPC”
  • the first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold.
  • the second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA.
  • the second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold.
  • the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell.
  • the UE 100 compares a result of the measurement with the one or more criteria.
  • the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100.
  • the master node 104A receives the message.
  • the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 601).
  • the report may comprise a new report type called a mobility method optimization (MMO) report.
  • the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO.
  • SHR successful handover report
  • SPR successful PSCell change report
  • the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison.
  • the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison.
  • the report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇ ), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell.
  • a cause of the at least two consecutive PSCell changes e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇
  • a time stayed e.g., indicated as an integer between 1 and 1023
  • the integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time.
  • the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM ⁇ CPC ⁇ or ENUM ⁇ SA ⁇ ).
  • the information may indicate the mobility procedure explicitly or implicitly.
  • the cause ENUM may implicitly indicate the mobility procedure.
  • the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes).
  • the master node 104A increments at least one counter based on the report. In other words, the master node 104A creates and analyzes counter statistics per PSCell border.
  • a corresponding counter e.g., called “too tight consecutive CPSs”
  • a corresponding counter e.g., called “Too widely spaced SAs”
  • the master node 104A transmits, to a network entity 111 such as a network management system (NMS), information indicating at least a value of the incremented at least one counter.
  • the network entity 111 may host a self- organizing network (SON) function.
  • SON self- organizing network
  • the network entity 111 determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes.
  • the information transmitted by the master node 104A causes the network entity 111 to determine whether to change the mobility procedure applied by the UE 100 for the cell border associated with the at least two consecutive PSCell changes.
  • the network entity 111 transmits, to the master node 104A, an indication for changing the mobility procedure applied by the UE 100 for the cell border.
  • the master node 104A receives the indication.
  • the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure.
  • FIG. 7 illustrates a signal flow diagram according to an example embodiment for SN-initiated reporting with a distributed SON. [0162] ⁇ Referring to FIG.
  • a first secondary node (SN1) 104B transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100.
  • the UE 100 receives the configuration.
  • the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0163] ⁇ The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode.
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes.
  • the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization.
  • the first threshold e.g., called “threshold_min_consecutive_CPC”
  • the first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold.
  • the second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA.
  • the second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold.
  • the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell.
  • the UE 100 compares a result of the measurement with the one or more criteria.
  • first secondary node and second secondary node are used to distinguish the secondary nodes, and they do not necessarily mean specific identifiers or a specific order of the secondary nodes.
  • the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison.
  • the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison.
  • the report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇ ), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell.
  • a cause of the at least two consecutive PSCell changes e.g., ENUM ⁇ CPC tight in succession ⁇ or ENUM ⁇ widely spaced SA ⁇
  • a time stayed e.g., indicated as an integer between 1 and 1023
  • the integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time.
  • the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM ⁇ CPC ⁇ or ENUM ⁇ SA ⁇ ).
  • the information may indicate the mobility procedure explicitly or implicitly.
  • the cause ENUM may implicitly indicate the mobility procedure.
  • the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes).
  • the second secondary node 104C transmits, or forwards, the report to the first secondary node 104B.
  • the report may be forwarded in an access and mobility indication.
  • the first secondary node 104B increments at least one counter based on the report.
  • the first secondary node 104B determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. In other words, the determination may be based on analyzing the counter statistics for the cell border. [0181] ⁇ At 708, based on the determination, the first secondary node 104B reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the first secondary node 104B may reconfigure the UE 100 to apply CPC instead of SA, or vice versa.
  • the first secondary node 104B may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure.
  • FIG. 8 illustrates a signal flow diagram according to an example embodiment for SN-initiated reporting with a centralized SON.
  • a first secondary node (SN1) 104B transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100.
  • the UE 100 receives the configuration.
  • the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization.
  • the first threshold e.g., called “threshold_min_consecutive_CPC”
  • the first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold.
  • the second threshold e.g., called “threshold_max_consecutive_SA” may be applied for UEs configured with SA.
  • the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison.
  • the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison.
  • the integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time.
  • the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM ⁇ CPC ⁇ or ENUM ⁇ SA ⁇ ).
  • the information may indicate the mobility procedure explicitly or implicitly.
  • the cause ENUM may implicitly indicate the mobility procedure.
  • the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes).
  • the second secondary node 104C transmits, or forwards, the report to the first secondary node 104B.
  • the report may be forwarded in an access and mobility indication.
  • the first secondary node 104B increments at least one counter based on the report.
  • the first secondary node 104B creates and analyzes counter statistics per PSCell border. In other words, the first secondary node 104B creates and analyzes counter statistics per PSCell border. [0199] ⁇ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession”, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0200] ⁇ As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA”, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented.
  • the first secondary node 104B transmits, to a network entity 111 such as a network management system (NMS), information indicating at least a value of the incremented at least one counter.
  • the network entity 111 may host a self- organizing network (SON) function.
  • SON self- organizing network
  • the network entity 111 determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes.
  • the information transmitted by the first secondary node 104B causes the network entity 111 to determine whether to change the mobility procedure applied by the UE 100 for the cell border associated with the at least two consecutive PSCell changes.
  • the network entity 111 transmits, to the first secondary node 104B, an indication for changing the mobility procedure applied by the UE 100 for the cell border.
  • the first secondary node 104B receives the indication.
  • the first secondary node 104B reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100.
  • the first secondary node 104B may reconfigure the UE 100 to apply CPC instead of SA, or vice versa.
  • the first secondary node 104B may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure.
  • one or more criteria e.g., the first threshold or the second threshold
  • FIG.9 illustrates a flow chart according to an example embodiment of a method performed by an apparatus 1100 depicted in FIG. 11.
  • the apparatus 1100 may be, or comprise, or be comprised in, a user equipment (UE) 100, 102.
  • the apparatus 1100 may be in a dual connectivity mode with two or more network nodes.
  • the apparatus 1100 receives a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus 1100.
  • the configuration may be received from a master node 104A or a secondary node 104B.
  • the apparatus 1100 performs a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure.
  • the apparatus 1100 compares a result of the measurement with the one or more criteria.
  • the apparatus 1100 transmits a message comprising a report associated with the at least two consecutive primary secondary cell changes.
  • the message may be transmitted to the master node 104A or the secondary node 104B.
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between the at least two consecutive primary secondary cell changes.
  • CPC conditional primary secondary cell change
  • the message may be transmitted if the result of the measurement is below the first threshold based on the comparison.
  • SA selective activation
  • the report may comprise information indicating at least one of: a cause of the at least two consecutive primary secondary cell changes, a time stayed in a source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of the source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of a target primary secondary cell of the at least two consecutive primary secondary cell changes, or one or more radio measurements of one or more neighbor cells.
  • the report may comprise information indicating the mobility procedure applied by the apparatus 1100.
  • the report may comprise information indicating at least one of: a number of prepared candidate target primary secondary cells during the at least two consecutive primary secondary cell changes, or a number of subsequent cell changes after the at least two consecutive primary secondary cell changes.
  • the apparatus 1100 does not transmit the message comprising the report.
  • the mobility procedure comprises a conditional primary secondary cell change (CPC) procedure
  • CPC conditional primary secondary cell change
  • FIG.10 illustrates a flow chart according to an example embodiment of a method performed by an apparatus 1200 depicted in FIG. 12.
  • the apparatus 1200 may be, or comprise, or be comprised in, a network node 104 of a radio access network, such as a master node 104A or a secondary node 104B, 104C.
  • a network node 104 of a radio access network such as a master node 104A or a secondary node 104B, 104C.
  • the apparatus 1200 transmits, to a user equipment 100, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment 100.
  • the apparatus 1200 receives a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment 100, wherein the report is generated and/or transmitted by the user equipment 100 based on the one or more criteria.
  • the apparatus 1200 may receive the message from the user equipment 100 or from another network node (e.g., from a secondary node 104B or 104C).
  • the one or more criteria may comprise at least one of a first threshold or a second threshold for the time between the at least two consecutive primary secondary cell changes.
  • the configuration may indicate the user equipment 100 to transmit the message if the result of the measurement is below the first threshold based on the comparison.
  • the configuration may indicate the user equipment 100 to transmit the message if the result of the measurement is above the second threshold based on the comparison.
  • the report may comprise information indicating at least one of: a number of prepared candidate target primary secondary cells during the at least two consecutive primary secondary cell changes, or a number of subsequent cell changes after the at least two consecutive primary secondary cell changes.
  • the apparatus 1200 may transmit the report to a self-organizing network (SON) function, which may be hosted in the apparatus 1200 or in another network entity 111.
  • SON self-organizing network
  • the apparatus 1200 may increment at least one counter based on the report; and determine, based on the at least one counter, whether to change the mobility procedure applied by the user equipment 100 for a cell border associated with the at least two primary secondary cell changes.
  • the apparatus 1200 may increment at least one counter based on the report; and transmit, to the network entity 111, information indicating at least a value of the incremented at least one counter, wherein the information causes the network entity 111 (or SON function) to determine whether to change the mobility procedure applied by the user equipment 100 for a cell border associated with the at least two primary secondary cell changes.
  • FIG. 11 illustrates an example of an apparatus 1100 comprising means for performing one or more of the example embodiments described above.
  • the apparatus 1100 may be an apparatus such as, or comprising, or comprised in, a user equipment (UE) 100, 102.
  • UE user equipment
  • the user equipment may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device.
  • the apparatus 1100 may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above.
  • the apparatus 1100 may comprise at least one processor 1110.
  • the at least one processor 1110 interprets instructions (e.g., computer program instructions) and processes data.
  • the at least one processor 1110 may comprise one or more programmable processors.
  • the at least one processor 1110 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application-specific integrated circuits (ASICs).
  • ASICs application-specific integrated circuits
  • the at least one processor 1110 is coupled to at least one memory 1120.
  • the at least one processor is configured to read and write data to and from the at least one memory 1120.
  • the at least one memory 1120 may comprise one or more memory units.
  • the memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory.
  • Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM).
  • Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage.
  • ROM read-only memory
  • PROM programmable read-only memory
  • EEPROM electronically erasable programmable read-only memory
  • flash memory optical storage or magnetic storage.
  • memories may be referred to as non- transitory computer readable media.
  • the term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).
  • the at least one memory 1120 stores computer readable instructions that are executed by the at least one processor 1110 to perform one or more of the example embodiments described above.
  • non-volatile memory stores the computer readable instructions
  • the at least one processor 1110 executes the instructions using volatile memory for temporary storage of data and/or instructions.
  • the computer readable instructions may refer to computer program code. [0237] ⁇ The computer readable instructions may have been pre-stored to the at least one memory 1120 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions by the at least one processor 1110 causes the apparatus 1100 to perform one or more of the example embodiments described above.
  • a “memory” or “computer-readable media” or “computer-readable medium” may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.
  • the term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).
  • the apparatus 1100 may further comprise, or be connected to, an input unit 1130.
  • the input unit 1130 may comprise one or more interfaces for receiving input.
  • the one or more interfaces may comprise for example one or more temperature, motion and/or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and/or one or more touch detection units.
  • the input unit 1130 may comprise an interface to which external devices may connect to.
  • the apparatus 1100 may also comprise an output unit 1140.
  • the output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD) and/or a liquid crystal on silicon (LCoS) display.
  • LED light emitting diode
  • LCD liquid crystal display
  • LCD liquid crystal on silicon
  • the output unit 1140 may further comprise one or more audio outputs.
  • the one or more audio outputs may be for example loudspeakers.
  • the apparatus 1100 further comprises a connectivity unit 1150.
  • the connectivity unit 1150 enables wireless connectivity to one or more external devices.
  • the connectivity unit 1150 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 1100 or that the apparatus 1100 may be connected to.
  • the at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna.
  • the connectivity unit 1150 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1100.
  • the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC).
  • ASIC application-specific integrated circuit
  • the connectivity unit 1150 may also provide means for performing at least some of the blocks or functions of one or more example embodiments described above.
  • the connectivity unit 1150 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.
  • DFE digital front end
  • ADC analog-to-digital converter
  • DAC digital-to-analog converter
  • frequency converter e.g., frequency converter
  • demodulator e.g., frequency converter
  • encoder/decoder circuitries controlled by the corresponding controlling units.
  • the processor 1110 is configured to cause the apparatus 1100 to perform the embodiments explained in FIGS.4 to 10 and the description thereof.
  • the processor 1110 causes the apparatus 1100 to receive at least one message (e.g., configuration and/or reconfiguration) of FIGS.
  • the apparatus 1100 may further comprise various components not illustrated in FIG. 11.
  • the various components may be hardware components and/or software components.
  • FIG. 12 illustrates an example of an apparatus 1200 comprising means for performing one or more of the example embodiments described above.
  • the apparatus 1200 may be an apparatus such as, or comprising, or comprised in, a network node 104 of a radio access network, such as a master node 104A or a secondary node 104B, 104C.
  • the network node may also be referred to, for example, as a network element, a radio access network (RAN) node, a next generation radio access network (NG-RAN) node, a NodeB, an eNB, a gNB, a base transceiver station (BTS), a base station, an NR base station, a 5G base station, an access node, an access point (AP), a cell site, a relay node, a repeater, an integrated access and backhaul (IAB) node, an IAB donor node, a distributed unit (DU), a central unit (CU), a baseband unit (BBU), a radio unit (RU), a radio head, a remote radio head (RRH), or a transmission
  • RAN radio
  • the apparatus 1200 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above.
  • the apparatus 1200 may be an electronic device comprising one or more electronic circuitries.
  • the apparatus 1200 may comprise a communication control circuitry 1210 such as at least one processor, and at least one memory 1220 storing instructions 1222 which, when executed by the at least one processor, cause the apparatus 1200 to carry out one or more of the example embodiments described above.
  • Such instructions 1222 may, for example, include computer program code (software).
  • the at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and/or blocks described above.
  • the processor is coupled to the memory 1220.
  • the processor is configured to read and write data to and from the memory 1220.
  • the memory 1220 may comprise one or more memory units.
  • the memory units may be volatile or non- volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non- volatile memory, or, alternatively, one or more units of volatile memory.
  • Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM).
  • Non- volatile memory may be for example read-only memory (ROM), programmable read- only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage.
  • memories may be referred to as non-transitory computer readable media.
  • non-transitory is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).
  • the memory 1220 stores computer readable instructions that are executed by the processor.
  • non-volatile memory stores the computer readable instructions, and the processor executes the instructions using volatile memory for temporary storage of data and/or instructions.
  • the computer readable instructions may have been pre-stored to the memory 1220 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1200 to perform one or more of the functionalities described above.
  • the memory 1220 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and/or removable memory.
  • the memory may comprise a configuration database for storing configuration data, such as a current neighbour cell list, and, in some example embodiments, structures of frames used in the detected neighbour cells.
  • the apparatus 1200 may further comprise or be connected to a communication interface 1230, such as a radio unit, comprising hardware and/or software for realizing communication connectivity with one or more wireless communication devices according to one or more communication protocols.
  • the communication interface 1230 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 1200 or that the apparatus 1200 may be connected to.
  • the communication interface 1230 may provide means for performing some of the blocks for one or more example embodiments described above.
  • the communication interface 1230 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to- analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units.
  • the communication interface 1230 provides the apparatus with radio communication capabilities to communicate in the wireless communication network.
  • the communication interface may, for example, provide a radio interface to one or more UEs 100, 102.
  • the apparatus 1200 may further comprise or be connected to another interface towards a core network 110, such as the network coordinator apparatus or AMF, and/or to the access nodes 104, 104A, 104B, 104C of the wireless communication network.
  • the apparatus 1200 may further comprise a scheduler 1240 that is configured to allocate radio resources.
  • the scheduler 1240 may be configured along with the communication control circuitry 1210 or it may be separately configured.
  • the apparatus 1200 may further comprise various components not illustrated in FIG. 12. The various components may be hardware components and/or software components.
  • circuitry may refer to one or more or all of the following: a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and b) combinations of hardware circuits and software, such as (as applicable): i) a combination of analog and/or digital hardware circuit(s) with software/firmware and ii) any portions of hardware processor(s) with software (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, to perform various functions); and c) hardware circuit(s) and/or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example firmware) for operation, but the software may not be present when it is not needed for operation.
  • circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware.
  • circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.
  • the control circuitry 1210 is configured to cause the apparatus 1200 to perform the embodiments explained in FIGS. 4 to 10 and the description thereof.
  • control circuitry 1210 causes the apparatus 1200 to transmit at least one message (e.g., configuration and/or reconfiguration) of FIGS. 4 to 10 or receive at least one message (e.g., report) via the communication interface Tx/Rx unit 1230.
  • control circuitry 1210 is configured to increase or decrease the counter and/or the determination whether to change the mobility procedure based on the report received from the user equipment 100.
  • the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.
  • ASICs application-specific integrated circuits
  • DSPs digital signal processors
  • DSPDs digital signal processing devices
  • PLDs programmable logic devices
  • FPGAs field programmable gate arrays
  • GPUs graphics processing units
  • processors controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.
  • the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein.
  • the software codes may be stored in a memory

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Abstract

Disclosed is a method comprising receiving, by an apparatus, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing, by the apparatus, a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing, by the apparatus, a result of the measurement with the one or more criteria; and transmitting, by the apparatus, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes.

Description

MONITORING EFFICIENCY OF MOBILITY PROCEDURE FIELD [0001]^ The following example embodiments relate to wireless communication. BACKGROUND [0002]^In wireless communication, a suboptimal mobility procedure may result in network resources to be wasted unnecessarily. As resources are limited, it is desirable to optimize the usage of network resources. BRIEF DESCRIPTION [0003]^The scope of protection sought for various example embodiments is set out by the claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the claims are to be interpreted as examples useful for understanding various embodiments. [0004]^According to an aspect, there is provided an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; perform a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; compare a result of the measurement with the one or more criteria; and transmit, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0005]^ According to another aspect, there is provided an apparatus comprising: means for receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; means for performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; means for comparing a result of the measurement with the one or more criteria; and means for transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0006]^ According to another aspect, there is provided a method comprising: receiving, by an apparatus, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing, by the apparatus, a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing, by the apparatus, a result of the measurement with the one or more criteria; and transmitting, by the apparatus, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0007]^According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0008]^According to another aspect, there is provided a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0009]^ According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. [0010]^ According to another aspect, there is provided an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receive a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. [0011]^ According to another aspect, there is provided an apparatus comprising: means for transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and means for receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. [0012]^ According to another aspect, there is provided a method comprising: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. [0013]^According to another aspect, there is provided a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. [0014]^According to another aspect, there is provided a computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. [0015]^ According to another aspect, there is provided a non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. LIST OF DRAWINGS [0016]^In the following, various example embodiments will be described in greater detail with reference to the accompanying drawings, in which FIG.1 illustrates an example of a wireless communication network; FIG.2 illustrates an example of a wireless communication system; FIG. 3 illustrates a scenario, where a user equipment is passing several primary secondary cells; FIG.4 illustrates a signal flow diagram; FIG.5 illustrates a signal flow diagram; FIG.6 illustrates a signal flow diagram; FIG.7 illustrates a signal flow diagram; FIG.8 illustrates a signal flow diagram; FIG.9 illustrates a flow chart; FIG.10 illustrates a flow chart; FIG.11 illustrates an example of an apparatus; FIG.12 illustrates an example of an apparatus. DETAILED DESCRIPTION [0017]^ The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. [0018]^Some example embodiments described herein may be implemented in a wireless communication network comprising a radio access network based on one or more of the following radio access technologies (RATs): Global System for Mobile Communications (GSM) or any other second generation radio access technology, Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband- code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, fourth generation (4G), fifth generation (5G), 5G new radio (NR), 5G-Advanced (i.e., 3GPP NR Rel-18 and beyond), or sixth generation (6G). Some examples of radio access networks include the universal mobile telecommunications system (UMTS) radio access network (UTRAN), the Evolved Universal Terrestrial Radio Access network (E-UTRA), or the next generation radio access network (NG-RAN). The wireless communication network may further comprise a core network, and some example embodiments may also be applied to network functions of the core network. [0019]^It should be noted that the embodiments are not restricted to the wireless communication network given as an example, but a person skilled in the art may also apply the solution to other wireless communication networks or systems provided with necessary properties. For example, some example embodiments may also be applied to a communication system based on IEEE 802.11 specifications, or a communication system based on IEEE 802.15 specifications. IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. [0020]^FIG. 1 depicts an example of a simplified wireless communication network showing some physical and logical entities. The connections shown in FIG.1 may be physical connections or logical connections. It is apparent to a person skilled in the art that the wireless communication network may also comprise other physical and logical entities than those shown in FIG.1. [0021]^ The example embodiments described herein are not, however, restricted to the wireless communication network given as an example but a person skilled in the art may apply the embodiments described herein to other wireless communication networks provided with necessary properties. [0022]^ The example wireless communication network shown in FIG. 1 includes an access network, such as a radio access network (RAN), and a core network 110. [0023]^FIG. 1 shows user equipment (UE) 100, 102 configured to be in a wireless connection on one or more communication channels in a radio cell with an access node (AN) 104 of an access network. The AN 104 may be an evolved NodeB (abbreviated as eNB or eNodeB), or a next generation evolved NodeB (abbreviated as ng-eNB), or a next generation NodeB (abbreviated as gNB or gNodeB), providing the radio cell. The wireless connection (e.g., radio link) from a UE to the access node 104 may be called uplink (UL) or reverse link, and the wireless connection (e.g., radio link) from the access node to the UE may be called downlink (DL) or forward link. UE 100 may also communicate directly with UE 102, and vice versa, via a wireless connection generally referred to as a sidelink (SL). It should be appreciated that the access node 104 or its functionalities may be implemented by using any node, host, server or access point etc. entity suitable for providing such functionalities. [0024]^The access network may comprise more than one access node, in which case the access nodes may also be configured to communicate with one another over links, wired or wireless. These links between access nodes may be used for sending and receiving control plane signaling and also for routing data from one access node to another access node. [0025]^The access node may comprise a computing device configured to control the radio resources of the access node. The access node may also be referred to as a base station, a base transceiver station (BTS), an access point, a cell site, a radio access node or any other type of node capable of being in a wireless connection with a UE (e.g., UEs 100, 102). The access node may include or be coupled to transceivers. From the transceivers of the access node, a connection may be provided to an antenna unit that establishes bi-directional radio links to UEs 100, 102. The antenna unit may comprise an antenna or antenna element, or a plurality of antennas or antenna elements. [0026]^The access node 104 may further be connected to a core network (CN) 110. The core network 110 may comprise an evolved packet core (EPC) network and/or a 5th generation core network (5GC). The EPC may comprise network entities, such as a serving gateway (S-GW for routing and forwarding data packets), a packet data network gateway (P-GW) for providing connectivity of UEs to external packet data networks, and a mobility management entity (MME). The 5GC may comprise one or more network functions, such as at least one of: a user plane function (UPF), an access and mobility management function (AMF), a location management function (LMF), and/or a session management function (SMF). [0027]^The core network 110 may also be able to communicate with one or more external networks 113, such as a public switched telephone network or the Internet, or utilize services provided by them. For example, in 5G wireless communication networks, the UPF of the core network 110 may be configured to communicate with an external data network via an N6 interface. In LTE wireless communication networks, the P-GW of the core network 110 may be configured to communicate with an external data network. [0028]^The illustrated UE 100, 102 is one type of an apparatus to which resources on the air interface may be allocated and assigned. The UE 100, 102 may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device just to mention but a few names. The UE may be a computing device operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of computing devices: a mobile phone, a smartphone, a personal digital assistant (PDA), a handset, a computing device comprising a wireless modem (e.g., an alarm or measurement device, etc.), a laptop computer, a desktop computer, a tablet, a game console, a notebook, a multimedia device, a reduced capability (RedCap) device, a wearable device (e.g., a watch, earphones or eyeglasses) with radio parts, a sensor comprising a wireless modem, or any computing device comprising a wireless modem integrated in a vehicle. [0029]^It should be appreciated that a UE may also be a nearly exclusive uplink-only device, of which an example may be a camera or video camera loading images or video clips to a network. A UE may also be a device having capability to operate in an Internet of Things (IoT) network, which is a scenario in which objects may be provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The UE may also utilize cloud. In some applications, the computation may be carried out in the cloud or in another UE. [0030]^The wireless communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in FIG.1 by “cloud” 114). [0031]^The wireless communication network may also comprise a central control entity, such as a network management system (NMS) 111, or the like. The NMS 111 is a centralized suite of software and hardware used to monitor, control, and administer the network infrastructure. The NMS 111 is responsible for a wide range of tasks such as fault management, configuration management, security management, performance management, and accounting management. The NMS 111 enables network operators to efficiently manage and optimize network resources, ensuring that the network delivers high performance, reliability, and security. [0032]^5G enables using multiple input – multiple output (MIMO) antennas in the access node 104 and/or the UE 100, 102, many more base stations or access nodes than an LTE network (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G wireless communication networks may support a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, such as (massive) machine- type communications (mMTC), including vehicular safety, different sensors and real- time control. [0033]^In 5G wireless communication networks, access nodes and/or UEs may have multiple radio interfaces, namely below 6GHz, cmWave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, for example, as a system, where macro coverage may be provided by the LTE, and 5G radio interface access may come from small cells by aggregation to the LTE. In other words, a 5G wireless communication network may support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6GHz – cmWave – mmWave). One of the concepts considered to be used in 5G wireless communication networks may be network slicing, in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the substantially same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility. [0034]^ In some example embodiments, an access node (e.g., access node 104) may comprise: a radio unit (RU) comprising a radio transceiver (TRX), i.e., a transmitter (Tx) and a receiver (Rx); one or more distributed units (DUs) 105 that may be used for the so-called Layer 1 (L1) processing and real-time Layer 2 (L2) processing; and a central unit (CU) 108 (also known as a centralized unit) that may be used for non- real-time L2 and Layer 3 (L3) processing. The CU 108 may be connected to the one or more DUs 105 for example via an F1 interface. Such an embodiment of the access node may enable the centralization of CUs relative to the cell sites and DUs, whereas DUs may be more distributed and may even remain at cell sites. The CU and DU together may also be referred to as baseband or a baseband unit (BBU). The CU and DU may also be comprised in a radio access point (RAP). [0035]^The CU 108 may be a logical node hosting radio resource control (RRC), service data adaptation protocol (SDAP) and/or packet data convergence protocol (PDCP), of the NR protocol stack for an access node. The DU 105 may be a logical node hosting radio link control (RLC), medium access control (MAC) and/or physical (PHY) layers of the NR protocol stack for the access node. The operations of the DU may be at least partly controlled by the CU. It should also be understood that the distribution of functions between DU 105 and CU 108 may vary depending on implementation. The CU may comprise a control plane (CU-CP), which may be a logical node hosting the RRC and the control plane part of the PDCP protocol of the NR protocol stack for the access node. The CU may further comprise a user plane (CU-UP), which may be a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol of the CU for the access node. [0036]^Cloud computing systems may also be used to provide the CU 108 and/or DU 105. A CU provided by a cloud computing system may be referred to as a virtualized CU (vCU). In addition to the vCU, there may also be a virtualized DU (vDU) provided by a cloud computing system. Furthermore, there may also be a combination, where the DU may be implemented on so-called bare metal solutions, for example application-specific integrated circuit (ASIC) or customer-specific standard product (CSSP) system-on-a-chip (SoC). [0037]^Edge cloud may be brought into the access network (e.g., RAN) by utilizing network function virtualization (NFV) and software defined networking (SDN). Using edge cloud may mean access node operations to be carried out, at least partly, in a computing system operationally coupled to a remote radio head (RRH) or a radio unit (RU) of an access node. It is also possible that access node operations may be performed on a distributed computing system or a cloud computing system located at the access node. Application of cloud RAN architecture enables RAN real-time functions being carried out at the access network (e.g., in a DU 105) and non-real-time functions being carried out in a centralized manner (e.g., in a CU 108). [0038]^ It should also be understood that the distribution of functions between core network operations and access node operations may differ in future wireless communication networks compared to that of the LTE or 5G, or even be non- existent. Some other technology advancements that may be used include big data and all-IP, which may change the way wireless communication networks are being constructed and managed. 5G (or new radio, NR) wireless communication networks may support multiple hierarchies, where multi-access edge computing (MEC) servers may be placed between the core network 110 and the access node 104. It should be appreciated that MEC may be applied in LTE wireless communication networks as well. [0039]^A 5G wireless communication network (“5G network”) may also comprise a non-terrestrial communication network, such as a satellite communication network, to enhance or complement the coverage of the 5G radio access network. For example, satellite communication may support the transfer of data between the 5G radio access network and the core network, enabling more extensive network coverage. Possible use cases may be providing service continuity for machine-to- machine (M2M) or Internet of Things (IoT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). A given satellite 106 in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on- ground cells may be created through an on-ground relay access node or by an access node 104 located on-ground or in a satellite. [0040]^It is obvious for a person skilled in the art that the access node 104 depicted in FIG.1 is just an example of a part of an access network (e.g., a radio access network) and in practice, the access network may comprise a plurality of access nodes, the UEs 100, 102 may have access to a plurality of radio cells, and the access network may also comprise other apparatuses, such as physical layer relay access nodes or other entities. At least one of the access nodes may be a Home eNodeB or a Home gNodeB. A Home gNodeB or a Home eNodeB is a type of access node that may be used to provide indoor coverage inside a home, office, or other indoor environment. [0041]^Additionally, in a geographical area of an access network (e.g., a radio access network), a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which may be large cells having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The access node(s) of FIG. 1 may provide any kind of these cells. A cellular radio network may be implemented as a multilayer access networks including several kinds of radio cells. In multilayer access networks, one access node may provide one kind of a radio cell or radio cells, and thus a plurality of access nodes may be needed to provide such a multilayer access network. [0042]^ For fulfilling the need for improving performance of access networks, the concept of “plug-and-play” access nodes may be introduced. An access network which may be able to use “plug-and-play” access nodes, may include, in addition to Home eNodeBs or Home gNodeBs, a Home Node B gateway, or HNB-GW (not shown in FIG.1). An HNB-GW, which may be installed within an operator’s access network, may aggregate traffic from a large number of Home eNodeBs or Home gNodeBs back to a core network of the operator. [0043]^FIG.2 illustrates an example of a wireless communication system, to which some example embodiments may be applied. FIG. 2 may be understood to depict a part of the wireless communication network of FIG. 1, but with greater accuracy with respect to dual connectivity (DC). [0044]^At least portions of the wireless communication system may be configured for implementing dual connectivity. Dual connectivity enables a UE 100 to be simultaneously connected to two cell groups: a master cell group (MCG) 210 and a secondary cell group (SCG) 220. The two cell groups 210, 220 may be associated with different access nodes 104A, 104B. The two cell groups 210, 220 may be based on different radio access technologies (e.g., LTE and 5G), or they may both be based on the same radio access technology (e.g., 5G). Herein the term “cell” refers to a radio cell. [0045]^The MCG 210 is a group of serving cells controlled by the master node (MN) 104A. The master node 104A is a RAN node providing the control plane connection to the core network 110. The MCG 210 comprises a primary cell (PCell) 211, i.e., the primary serving cell of the MCG 210, and optionally one or more secondary cells (SCells) 212. The PCell 211 is a cell operating on a primary frequency that may be used for initial access under the MCG 210. An SCell is a cell, operating on a secondary frequency, which may be configured once an RRC connection is established, and which may be used to provide additional radio resources. [0046]^The SCG 220 is a group of serving cells controlled by the secondary node (SN) 104B. The secondary node 104B is a RAN node providing additional resources to the UE 100. The SCG 220 comprises a primary secondary cell (PSCell) 221, i.e., the primary serving cell of the SCG 220, and optionally one or more SCells 222. The PSCell 221 is a cell that may be used for initial access under the SCG 220. [0047]^ In NR Release 16, the conditional primary secondary cell change (CPC) procedure has been specified for an intra-SN scenario (i.e., changing to a target PSCell controlled by the same SN that also controls the source PSCell) with MN- initiated CPC and SN-initiated CPC distinguished by usage of different signalling resource bearers (SRB). SN-initiated may be used if SRB3 is established, otherwise the cell change related reporting and signalling may be carried out via SRB1 to MN. In NR Release 17, CPC has been extended for inter-SN scenarios (i.e., changing to a target PSCell controlled by a different SN than the SN that controls the source PSCell) with MN-initiated CPC and SN-initiated CPC. The procedure of changing the linkage to different SN is to be carried out by the MN. In case of SN-initiated CPC, the SN starts the process with a request message, if the UE 100 is reporting via SRB3 to the SN. The signaling associated with SN-initiated inter-SN CPC is described in the following. [0048]^As a first step, the source SN indicates to the MN the identifiers (IDs) of the target SNs that shall be contacted for preparing as candidate target PSCell(s) for CPC. The source SN suggests a list of PSCell(s) to be prepared by each target SN and provides a CPC execution condition for each suggested target PSCell. In other words, the CPC execution conditions are not forwarded to the target SNs, but are sent with a configuration message to the UE by the MN. Moreover, the source SN indicates the maximum number of PSCells that can be prepared by each target SN, i.e., the actual number of prepared cells can be equal to or lower than the maximum of the list of suggested PSCells. [0049]^ The MN sends an Addition Request message to each target SN indicated by the source SN. The Addition Request includes the list of PSCells that are suggested by the source SN along with the maximum number of PSCells that can be prepared. [0050]^ The target SN decides on the candidate target PSCell(s) to be prepared among the suggested list. The target SN cannot select a PSCell that is not included in the list. [0051]^ The target SN sends to the MN the CPC configuration for each prepared target PSCell and the ID(s) of the prepared target PSCell(s). [0052]^The MN sends to the UE a conditional (re-)configuration containing the CPC configurations of the candidate target PSCell(s) along with the CPC execution conditions. [0053]^The UE sends a message to the MN confirming the reception of the conditional reconfiguration, and the MN confirms in turn the SN change preparation to the source SN. [0054]^The MN sends the SN Change Confirm message towards the source SN to indicate that the CPC is prepared, and in such case the source SN continues providing user data to the UE. [0055]^ The UE evaluates the CPC execution conditions of the prepared target PSCell(s). [0056]^When the CPC execution condition is met for example for a PSCell candidate in target SN 1, the UE sends a message to the MN indicating the execution of the CPC configuration. The message includes an embedded SN RRC Reconfiguration Complete to the target SN 1, which is sent by the MN to the target SN 1. The UE then completes the random access to the new target PSCell. [0057]^The signaling for MN-initiated inter-SN CPC is similar to the SN- initiated inter-SN CPC described above, except that the first step is not needed. In MN- initiated CPC, the MN provides in the SN Addition Request the list of PSCells that are suggested to be prepared by the target SN along with the maximum number of PSCells that can be prepared by the target SN. Moreover, the MN configures the UE with the CPAC execution conditions for the prepared PSCells. [0058]^NR Release 18 is introducing a procedure called selective activation (SA) of cell group. The selective activation of cell groups should support an early preparation of future subsequent CPCs, and the initial focus of Release 18 is on SCG by applying in advance configurations to reduce the signaling overhead. However, the selective activation of cell group is foreseen to be applicable also to the case when the cell group is MCG (and SCG). In case of SA of MCG, the UE may keep the conditional handover configurations after executing a handover and just activates those for further cell changes. [0059]^ In contrast to CPC, SA will not release the prepared potential candidate PSCells, which might also be candidates from the perspective of the new source PSCell after the PSCell change completion. Furthermore, the UE does not release the conditional configuration of other candidate PSCells for subsequent CPCs, provided that they are applicable with respect to the new reference source PSCell. [0060]^SA may result in benefits in terms of signaling overhead reduction for fast PSCell changes in immediate succession due to small cells and a certain anticipation of the UE movement. [0061]^However, currently, there is no method available that would allow to judge the efficiency of the applied mobility procedure (e.g., CPC or SA) in terms of mobility performance, waste of protocol resources, and signaling overhead. In the UE history information (UHI), the time spent in the cell is continuously logged. However, the UE history information is not actively reported and does not distinguish between different mobility procedures. Therefore, it is not clear from the reported UE history which mobility procedure was in use. Also, other rather relevant information, such as the number of reported target cells, is not available in the UE history information. Therefore, the UE history information alone is not sufficient. [0062]^The pros and cons of CPC and SA are explained in the following with the help of FIG. 3. FIG. 3 illustrates a scenario, where the UE 100 is passing several PSCells 221A, 221B, 221C, 221D. [0063]^ In FIG. 3, the UE 100 moves along the trajectory indicated by the black arrow, and the UE is changing from single-connectivity at point 301 to dual- connectivity at point 302 by means of conditional primary secondary cell addition (CPA), for instance. In the following, from point 303 and onwards, the cell changes are analyzed with respect to the two mobility procedures (i.e., CPC and SA). [0064]^At point 303, for instance, an A3 Event can be used for CPC or SA preparation triggered by the second PSCell 221B and strong measurements of the third PSCell 221C and the fourth PSCell 221D. [0065]^For both CPC and SA, the MN 104A sends, for the preparation of the second PSCell 221B, the third PSCell 221C, and the fourth PSCell 221D as potential candidate target cells, a SN ADDITION REQUEST message to the target SN(s) serving these PSCells 221B, 221C, 221D. With an SN ADDITION REQUEST ACK message from the target SN(s), the MN 104A receives, for each target PSCell 221B, 221C, 221D, all the needed information to access the cell, such as the cell radio network temporary identifier (C-RNTI), security algorithm identifiers, and a dedicated random-access channel (RACH) preamble for contention-free random access (CFRA). [0066]^In case of SA, the SN ADDITION REQEST message from the MN 104A to the target SN(s) may include information about the other target candidate cells being prepared in parallel, so that the required conditional configuration (condConfig) measurement settings can be provided to configure the UE 100 in advance. [0067]^For both CPC and SA, the MN 104A configures the UE 100 with an RRC Reconfiguration with a synchronization message that includes the condConfig parameters for the three envisaged target PSCells 221B, 221C, 221D. For example, the UE 100 may be configured with the following condCofig parameters: A3(P1->P2), A3(P1->P3), A3(P1->P4). [0068]^A3(P1->P2) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the second PSCell 221B. [0069]^A3(P1->P3) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the third PSCell 221C. [0070]^A3(P1->P4) refers to an A3 event configured to trigger a cell change from the first PSCell 221A to the fourth PSCell 221D. [0071]^In case of SA, the UE 100 may be configured with further condConfig parameters, which may be provided with the SN ADDITION REQ ACK from the target SN(s) to the MN 104A: from the second PSCell 221B: A3(P2->P1), A3(P2->P3), A3(P2- >P4); from the third PSCell 221C: A3(P3->P1), A3(P3->P2), A3(P3->P4); and from the fourth PSCell 221D: A3(P4->P1), A3(P4->P2), A3(P4->P3). However, these further condConfig parameters may be marked as deactivated as long as the UE 100 is connected to the first PSCell 221A. [0072]^A3(P2->P1) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the first PSCell 221A. [0073]^A3(P2->P3) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the third PSCell 221C. [0074]^A3(P2->P4) refers to an A3 event configured to trigger a cell change from the second PSCell 221B to the fourth PSCell 221D. [0075]^A3(P3->P1) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the first PSCell 221A. [0076]^A3(P3->P2) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the second PSCell 221B. [0077]^A3(P3->P4) refers to an A3 event configured to trigger a cell change from the third PSCell 221C to the fourth PSCell 221D. [0078]^A3(P4->P1) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the first PSCell 221A. [0079]^A3(P4->P2) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the second PSCell 221B. [0080]^A3(P4->P3) refers to an A3 event configured to trigger a cell change from the fourth PSCell 221D to the third PSCell 221C. [0081]^At point 304, condConfig A3(P1->P4) triggers synchronization (i.e., random access) at the UE 100 with the fourth PSCell 221D (i.e., the UE 100 autonomously executes a handover). [0082]^In case of CPC, with completion of the handover to the fourth PSCell 221D, the preparations of the second PSCell 221B and the third PSCell 221C are released by sending SgNB Release Request messages, and the UE 100 is newly configured with a default measurement, which will trigger another CPC preparation. There is no UE CPC execution condConfig at this time. An advantage of releasing the preparations is that blocked resources due to preparation of unused target cells are freed. However, a disadvantage of releasing the preparations is that the preparation might be a hurdle for fast subsequent cell changes, since the UE 100 has to go through the preparation phase before another handover can be executed. [0083]^In case of SA, with completion of the handover to the fourth PSCell 221D, the preparations of the second PSCell 221B and the third PSCell 221C remain, and the first PSCell 221A will be prepared as a candidate target PSCell. The UE 100 activates the condConfig for the fourth PSCell 221D: A3(P4->P1), A3(P4->P2), A3(P4- >P3) for the conditional autonomous handover execution, while deactivating the former conditional execution criterion for the first PSCell 221A. An advantage of keeping the preparations is that immediate UE-autonomous handover execution is possible for fast subsequent cell changes. However, a disadvantage of keeping the preparations is that resources of prepared and unused cells remain blocked, and thus the UE memory usage is increased due to numerous condConfig options and sync parameters for each candidate cell. [0084]^At point 305 (only needed for CPC, since the preparations are all in place for SA), for instance, an A3 Event is again used to trigger the CPC preparation (here triggered by the third PSCell 221C), which includes a neighbor measurement list highlighting another strong measurement of the second PSCell 221B, while the signal strength of the first PSCell 221A is low. [0085]^In case of CPC, the MN 104A sends, for the preparation of the second PSCell 221B and the third PSCell 221C as potential candidate target cells, an SN ADDITION REQUEST message to the target SN(s) serving these PSCells 221B, 221C. With an SN ADDITION REQUEST ACK message from the target SN(s), the MN 104A receives, for each target cell, all the needed information to access the cell, such as C- RNTI, security algorithm identifiers, and a dedicated RACH preamble for CFRA. The MN 104A configures the UE 100 with an RRC Reconfiguration with a synchronization message that includes the condConfig parameters for the two envisaged target cells 221B, 221C, i.e., A3(P4->P2), A3(P4->P3). [0086]^ At point 306, condConfig A3(P4->P3) triggers synchronization (random access) at the UE 100 with the third PSCell 221C (i.e., handover execution). Depending on the velocity of the UE 100, the UE’s secondary link may now remain for a while. [0087]^In case of CPC, with completion of the handover to the third PSCell 221C, the preparation of the second PSCell 221B is released by sending SgNB Release Request messages, and the UE 100 is newly configured with a default measurement for CPC preparation of potential candidate cells. There is no UE CPC execution condConfig at this time, but it should not be an issue, if the UE 100 stays in the third PSCell 221C for a while. [0088]^In case of SA, with completion of the handover to the third PSCell 221C, the preparations of the second PSCell 221B, the fourth PSCell 221D (and the first PSCell 221A) remain. The UE 100 activates another condConfig setting for the third PSCell 221C: A3(P3->P1), A3(P3->P2), A3(P3->P4) for CPC execution. The former one for the fourth PSCell 221D is deactivated. If the UE 100 stays in the third PSCell 221C for a while, the long-term blocking of the network resources needed for the autonomous handover execution to an arbitrary neighbor cell is somewhat too excessive. [0089]^At point 307 (only needed for CPC, since the fourth PSCell 221D is prepared for SA), for instance, an A3 Event for CPC preparation is triggered by the fourth PSCell 221D, while all other neighbor cells are rather weak. [0090]^In case of CPC, from the reported measurement list, only the fourth PSCell 221D is identified as a potential candidate target cell. Therefore, the MN 104A sends an SN ADDITION REQUEST message to the target SN(s) serving the fourth PSCell 221D. With an SN ADDITION REQ ACK message from that target SN, the MN 104A receives, for that target cell, all the needed information to access the cell, such as C- RNTI, security algorithm identifiers, and a dedicated RACH preamble for CFRA. The MN 104A configures the UE 100 with RRC Reconfiguration with a synchronization message that includes the condConfig parameters for one envisaged target cell, i.e., A3(P3->P4). [0091]^ At point 308, condConfig A3(P3->P4) triggers synchronization (random access) at the UE 100 with the fourth PSCell 221D (i.e., handover execution). [0092]^Based on the above (see points 305 and 307), CPC requires more signaling compared to SA in terms of UE measurement reports, inter-node signaling for the preparation (e.g., SN ADDITION REQUEST, etc.), and the RRC Reconfiguration message to the UE, as well as the SN RELEASE REQUEST messages after successful handover execution. On the other hand, the network resource blockage is reduced with CPC compared to SA. For example, with SA, between points 306 and 308, the resources for all cells 221A, 221B, 221C, 221D (including the second PSCell 221B, which is never used), are blocked for quite a while. [0093]^The conclusion of the above scenario is that SA may only be useful, when several fast subsequent cell changes need to be managed. However, currently, there are no means to detect those deployment areas (cells or a cell layout), where SA may be a more optimal mobility procedure over CPC (and vice versa), since planning tools based on empirical propagation models are not able to predict shadow fading and overshooters in detail. Shadow fading means that signals fade away due to obstacles. On the other hand, other clutter types such as water surfaces may result in unattenuated propagation and so-called overshooters. [0094]^ In other words, there is a need for a method for monitoring the performance of the mobility procedure, in order to help apply the right mobility procedure at the right place and moment. [0095]^Some example embodiments provide such a method for monitoring the efficiency of the applied mobility procedure (e.g., CPC or SA) for PSCell changes of a UE using dual connectivity. Some example embodiments may utilize one or more new measurement criteria, which trigger information reporting for example to a RAN-based self-organizing network (SON) instance, which in turn uses this information to optimize the network such that each cell or cell group is configured with the best- performing and most efficient mobility procedure. In other words, the new measurement criteria allow to determine which mobility procedure (e.g., CPC or selective activation) is optimal for a specific cell border (e.g., between PSCells 221A and 221B of FIG. 3) within the considered SCG or for a whole set of PSCells within the considered SCG. The one or more criteria may be defined in terms of minimizing both the amount of the control data to be transmitted, and the network resource blockage due to unnecessary target cell preparations. [0096]^For example, one new criterion may be applied to UEs configured for the CPC procedure. This criterion relates to the measured time between at least two consecutive (CPC-based) PSCell changes, and this criterion may trigger logging of specific information, if the measured time is shorter than a first threshold (e.g., called “threshold_min_consecutive_CPC”). This logged information may be reported to a network entity (e.g., hosting a SON instance). At the network entity, for the cell border of these two consecutive PSCell changes, a counter may be incremented, wherein this counter expresses that the two consecutive CPC-based cell changes are “tight in succession”, which indicates that SA may be more optimal compared to CPC. [0097]^ Another criterion may be applied to UEs configured for the SA procedure. This criterion relates to the measured time between two consecutive (SA- based) PSCell changes, and this criterion would trigger logging of specific information, if the measured time is longer than a second threshold (e.g., called “threshold_max_consecutive_SA”). This logged information may be reported to a network entity (e.g., hosting a SON instance). At the network entity, for this cell border of these two consecutive PSCell changes, a counter is incremented, wherein this counter expresses that the two consecutive SA-based cell changes are “widely spaced SA”, which indicates that SA may waste network resources and CPC would be more optimal, since time for preparation is not an issue in this case. [0098]^The counters may be statistically analyzed and used to update the PSCell-related mobility configuration responsible for the UE mobility configuration (e.g., by means of an RRC Reconfiguration procedure). Thus, after a while, each cell pair or even cell group may reach the optimal mobility configuration. [0099]^Some example embodiments are described below using principles and terminology of 5G radio access technology without limiting the example embodiments to 5G radio access technology, however. [0100]^FIG. 4 illustrates a signal flow diagram according to an example embodiment. [0101]^Referring to FIG.4, at 401, a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration message) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100. The UE 100 receives the configuration. For example, the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0102]^The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode. [0103]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes. For example, the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization. [0104] The first threshold (e.g., called “threshold_min_consecutive_CPC”) may be applied for UEs configured with CPC. The first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold. [0105] The second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA. The second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold. [0106]^At 402, the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell (e.g., PSCell 221A), and monitor the time until the next CPC or SA execution to a new PSCell (e.g., PSCell 221B). [0107]^At 403, the UE 100 compares a result of the measurement with the one or more criteria. [0108]^At 404, the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The master node 104A receives the message. In other words, the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 401). For example, the report may comprise a new report type called a mobility method optimization (MMO) report. Alternatively, the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO. [0109]^In case the mobility procedure comprises a CPC procedure, then the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison. [0110]^In case the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison. [0111]^The report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM {CPC tight in succession} or ENUM {widely spaced SA}), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell. The integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA). [0112]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM {CPC} or ENUM {SA}). The information may indicate the mobility procedure explicitly or implicitly. For example, the cause ENUM may implicitly indicate the mobility procedure. [0113]^In case the mobility procedure comprises the selective activation of cell group procedure, the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent (SA-based) cell changes after the at least two consecutive PSCell changes, i.e., the number of further already configured hops (the final SON decision may use this information when considering a series of PSCell changes). [0114]^At 405, the master node 104A transmits the report to a network entity 111, such as a network management system (NMS). The network entity 111 may host a self-organizing network (SON) function. [0115]^At 406, the network entity 111 increments at least one counter based on the report. [0116]^ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession“, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0117]^As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA “, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented. [0118]^At 407, the network entity 111 (or the SON function) determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. [0119]^At 408, based on determining to change the mobility procedure, the network entity 111 transmits, to the master node 104A, an indication for changing the mobility procedure applied by the UE 100 for the cell border. The master node 104A receives the indication. [0120]^At 409, based on receiving the indication from the network entity 111, the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure. [0121]^FIG. 5 illustrates a signal flow diagram according to an example embodiment for MN-initiated reporting with a distributed SON. [0122]^Referring to FIG.5, at 501, a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100. The UE 100 receives the configuration. For example, the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0123]^The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode. [0124]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes. For example, the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization. [0125]^The first threshold (e.g., called “threshold_min_consecutive_CPC”) may be applied for UEs configured with CPC. The first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold. [0126]^The second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA. The second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold. [0127]^At 502, the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell. [0128]^At 503, the UE 100 compares a result of the measurement with the one or more criteria. [0129]^At 504, the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The master node 104A receives the message. In other words, the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 501). For example, the report may comprise a new report type called a mobility method optimization (MMO) report. Alternatively, the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO. [0130]^In case the mobility procedure comprises a CPC procedure, then the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison. [0131]^In case the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison. [0132] The report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM {CPC tight in succession} or ENUM {widely spaced SA}), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell. The integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time. [0133]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM {CPC} or ENUM {SA}). The information may indicate the mobility procedure explicitly or implicitly. For example, the cause ENUM may implicitly indicate the mobility procedure. [0134]^In case the mobility procedure comprises the selective activation of cell group procedure, the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes). [0135]^At 505, the master node 104A increments at least one counter based on the report. In other words, the master node 104A creates and analyzes counter statistics per PSCell border. The master node 104A may host a self-organizing network (SON) function. [0136]^ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession“, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0137]^As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA “, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented. [0138]^At 506, the master node 104A (or the SON function) determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. In other words, the determination may be based on analyzing the counter statistics for the cell border. [0139]^ At 507, based on the determination, the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure. [0140]^FIG. 6 illustrates a signal flow diagram according to an example embodiment for MN-initiated reporting with a centralized SON. [0141]^Referring to FIG.6, at 601, a master node (MN) 104A transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100. The UE 100 receives the configuration. For example, the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0142]^The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode. [0143]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes. For example, the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization. [0144]^The first threshold (e.g., called “threshold_min_consecutive_CPC”) may be applied for UEs configured with CPC. The first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold. [0145]^The second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA. The second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold. [0146]^At 602, the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell. [0147]^At 603, the UE 100 compares a result of the measurement with the one or more criteria. [0148]^At 604, the UE 100 transmits, to the master node 104A, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The master node 104A receives the message. In other words, the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 601). For example, the report may comprise a new report type called a mobility method optimization (MMO) report. Alternatively, the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO. [0149]^In case the mobility procedure comprises a CPC procedure, then the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison. [0150]^In case the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison. [0151]^The report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM {CPC tight in succession} or ENUM {widely spaced SA}), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell. The integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time. [0152]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM {CPC} or ENUM {SA}). The information may indicate the mobility procedure explicitly or implicitly. For example, the cause ENUM may implicitly indicate the mobility procedure. [0153]^In case the mobility procedure comprises the selective activation of cell group procedure, the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes). [0154]^At 605, the master node 104A increments at least one counter based on the report. In other words, the master node 104A creates and analyzes counter statistics per PSCell border. [0155]^ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession“, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0156]^As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA “, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented. [0157]^At 606, the master node 104A transmits, to a network entity 111 such as a network management system (NMS), information indicating at least a value of the incremented at least one counter. The network entity 111 may host a self- organizing network (SON) function. [0158]^At 607, the network entity 111 (or the SON function) determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. In other words, the information transmitted by the master node 104A causes the network entity 111 to determine whether to change the mobility procedure applied by the UE 100 for the cell border associated with the at least two consecutive PSCell changes. [0159]^At 608, based on determining to change the mobility procedure, the network entity 111 transmits, to the master node 104A, an indication for changing the mobility procedure applied by the UE 100 for the cell border. The master node 104A receives the indication. [0160]^At 609, based on receiving the indication from the network entity 111, the master node 104A reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the master node 104A may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The master node 104A may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure. [0161]^FIG. 7 illustrates a signal flow diagram according to an example embodiment for SN-initiated reporting with a distributed SON. [0162]^ Referring to FIG. 7, at 701, a first secondary node (SN1) 104B transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100. The UE 100 receives the configuration. For example, the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0163]^The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode. [0164]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes. For example, the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization. [0165]^The first threshold (e.g., called “threshold_min_consecutive_CPC”) may be applied for UEs configured with CPC. The first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold. [0166]^The second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA. The second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold. [0167]^At 702, the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. For example, the UE 100 may start a timer upon handover completion to the current serving cell, and monitor the time until the next CPC or SA execution to a new PSCell. [0168]^At 703, the UE 100 compares a result of the measurement with the one or more criteria. [0169]^At 704, the UE 100 transmits, to a second secondary node (SN2) 104C, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The second secondary node 104C receives the message. In other words, the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 701). For example, the report may comprise a new report type called a mobility method optimization (MMO) report. Alternatively, the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO. [0170]^ Herein the terms “first secondary node” and “second secondary node” are used to distinguish the secondary nodes, and they do not necessarily mean specific identifiers or a specific order of the secondary nodes. [0171]^In case the mobility procedure comprises a CPC procedure, then the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison. [0172]^In case the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison. [0173]^The report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM {CPC tight in succession} or ENUM {widely spaced SA}), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell. The integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time. [0174]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM {CPC} or ENUM {SA}). The information may indicate the mobility procedure explicitly or implicitly. For example, the cause ENUM may implicitly indicate the mobility procedure. [0175]^In case the mobility procedure comprises the selective activation of cell group procedure, the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes). [0176]^At 705, the second secondary node 104C transmits, or forwards, the report to the first secondary node 104B. For example, the report may be forwarded in an access and mobility indication. [0177]^ At 706, the first secondary node 104B increments at least one counter based on the report. In other words, the first secondary node 104B creates and analyzes counter statistics per PSCell border. The first secondary node 104B may host a self-organizing network (SON) function. [0178]^ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession“, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0179]^As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA “, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented. [0180]^ At 707, the first secondary node 104B (or the SON function) determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. In other words, the determination may be based on analyzing the counter statistics for the cell border. [0181]^At 708, based on the determination, the first secondary node 104B reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the first secondary node 104B may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The first secondary node 104B may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure. [0182]^FIG. 8 illustrates a signal flow diagram according to an example embodiment for SN-initiated reporting with a centralized SON. [0183]^ Referring to FIG. 8, at 801, a first secondary node (SN1) 104B transmits, to a UE 100, a configuration (e.g., via RRC reconfiguration) indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the UE 100. The UE 100 receives the configuration. For example, the configuration may comprise an “OtherConfig” information element, wherein a new information element (e.g., called “MMO-Monitor-Config”) or a “SuccessHO-Config” information element may include the one or more criteria. [0184]^The UE 100 may be in RRC_CONNECTED state and operating in dual connectivity mode. [0185]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between at least two consecutive PSCell changes. For example, the time between the at least two consecutive PSCell changes may refer to the time elapsed between random access completion (UL synchronization completion) with the currently serving PSCell and the autonomously triggered execution (random access) with the next target PSCell identified by condConfig parameterization. [0186]^The first threshold (e.g., called “threshold_min_consecutive_CPC”) may be applied for UEs configured with CPC. The first threshold may represent a time span where CPC gets inefficient, if the measured time is below the first threshold. [0187]^The second threshold (e.g., called “threshold_max_consecutive_SA”) may be applied for UEs configured with SA. The second threshold may represent a time span where SA gets inefficient, if the measured time is above the second threshold. [0188]^At 802, the UE 100 performs a measurement of the time between at least two consecutive PSCell changes performed by the UE 100 according to the mobility procedure. [0189]^At 803, the UE 100 compares a result of the measurement with the one or more criteria. [0190]^At 804, the UE 100 transmits, to a second secondary node (SN2) 104C, based on the comparison, a message comprising a report associated with the at least two consecutive PSCell changes performed by the UE 100. The second secondary node 104C receives the message. In other words, the report is generated and transmitted by the UE 100 based on the one or more criteria (i.e., the configuration of 801). For example, the report may comprise a new report type called a mobility method optimization (MMO) report. Alternatively, the report may be comprised in a successful handover report (SHR) or in a successful PSCell change report (SPR) including new information for MMO. [0191]^ Herein the terms “first secondary node” and “second secondary node” are used to distinguish the secondary nodes, and they do not necessarily mean specific identifiers or a specific order of the secondary nodes. [0192]^In case the mobility procedure comprises a CPC procedure, then the message may be transmitted, if the result of the measurement is below the first threshold based on the comparison. [0193]^In case the mobility procedure comprises a selective activation of cell group procedure, then the message may be transmitted, if the result of the measurement is above the second threshold based on the comparison. [0194]^The report may comprise information indicating at least one of: a cause of the at least two consecutive PSCell changes (e.g., ENUM {CPC tight in succession} or ENUM {widely spaced SA}), a time stayed (e.g., indicated as an integer between 1 and 1023) in a source PSCell of the at least two consecutive PSCell changes, an identity of the source PSCell of the at least two consecutive PSCell changes, an identity of a target PSCell of the at least two consecutive PSCell changes, or one or more radio measurements of one or more neighbor cells of the source PSCell and/or the target PSCell. The integer between 1 and 1023 may refer to seconds (e.g., in case of CPC) or minutes (e.g., in case of SA) in time. [0195]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the UE 100 (e.g., ENUM {CPC} or ENUM {SA}). The information may indicate the mobility procedure explicitly or implicitly. For example, the cause ENUM may implicitly indicate the mobility procedure. [0196]^In case the mobility procedure comprises the selective activation of cell group procedure, the report may additionally comprise information indicating at least one of: a number of prepared candidate target PSCells during the at least two consecutive PSCell changes (the higher the number, the higher the waste of network resources), or a number of subsequent cell changes after the at least two consecutive PSCell changes (the final SON decision may use this information when considering a series of PSCell changes). [0197]^At 805, the second secondary node 104C transmits, or forwards, the report to the first secondary node 104B. For example, the report may be forwarded in an access and mobility indication. [0198]^ At 806, the first secondary node 104B increments at least one counter based on the report. In other words, the first secondary node 104B creates and analyzes counter statistics per PSCell border. In other words, the first secondary node 104B creates and analyzes counter statistics per PSCell border. [0199]^ For example, for a report indicative of the CPC procedure and trigger cause “CPC tight in succession”, a corresponding counter (e.g., called “too tight consecutive CPSs”) may be incremented. [0200]^As another example, for a report indicative of the SA procedure and trigger cause “widely spaced SA”, a corresponding counter (e.g., called “Too widely spaced SAs”) may be incremented. [0201]^At 807, the first secondary node 104B transmits, to a network entity 111 such as a network management system (NMS), information indicating at least a value of the incremented at least one counter. The network entity 111 may host a self- organizing network (SON) function. [0202]^At 808, the network entity 111 (or the SON function) determines, based on the at least one counter, whether to change the mobility procedure applied by the UE 100 for a cell border associated with the at least two consecutive PSCell changes. In other words, the information transmitted by the first secondary node 104B causes the network entity 111 to determine whether to change the mobility procedure applied by the UE 100 for the cell border associated with the at least two consecutive PSCell changes. [0203]^At 809, based on determining to change the mobility procedure, the network entity 111 transmits, to the first secondary node 104B, an indication for changing the mobility procedure applied by the UE 100 for the cell border. The first secondary node 104B receives the indication. [0204]^At 810, based on receiving the indication from the network entity 111, the first secondary node 104B reconfigures (e.g., via RRC reconfiguration) the UE 100 to change the mobility procedure applied by the UE 100. For example, the first secondary node 104B may reconfigure the UE 100 to apply CPC instead of SA, or vice versa. The first secondary node 104B may also configure the UE 100 with one or more criteria (e.g., the first threshold or the second threshold) corresponding to the new mobility procedure. [0205]^FIG.9 illustrates a flow chart according to an example embodiment of a method performed by an apparatus 1100 depicted in FIG. 11. For example, the apparatus 1100 may be, or comprise, or be comprised in, a user equipment (UE) 100, 102. The apparatus 1100 may be in a dual connectivity mode with two or more network nodes. [0206]^Referring to FIG. 9, in block 901, the apparatus 1100 receives a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus 1100. For example, the configuration may be received from a master node 104A or a secondary node 104B. [0207]^In block 902, the apparatus 1100 performs a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure. [0208]^ In block 903, the apparatus 1100 compares a result of the measurement with the one or more criteria. [0209]^In block 904, if the one or more criteria are fulfilled based on the comparison (block 903: yes), the apparatus 1100 transmits a message comprising a report associated with the at least two consecutive primary secondary cell changes. For example, the message may be transmitted to the master node 104A or the secondary node 104B. [0210]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between the at least two consecutive primary secondary cell changes. [0211]^ In case the mobility procedure comprises a conditional primary secondary cell change (CPC) procedure, then the message may be transmitted if the result of the measurement is below the first threshold based on the comparison. [0212]^In case the mobility procedure comprises a selective activation (SA) of cell group procedure, then the message may be transmitted if the result of the measurement is above the second threshold based on the comparison. [0213]^The report may comprise information indicating at least one of: a cause of the at least two consecutive primary secondary cell changes, a time stayed in a source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of the source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of a target primary secondary cell of the at least two consecutive primary secondary cell changes, or one or more radio measurements of one or more neighbor cells. [0214]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the apparatus 1100. [0215]^Alternatively, or additionally (e.g., in case the mobility procedure comprises SA), the report may comprise information indicating at least one of: a number of prepared candidate target primary secondary cells during the at least two consecutive primary secondary cell changes, or a number of subsequent cell changes after the at least two consecutive primary secondary cell changes. [0216]^In block 905, if the one or more criteria are not fulfilled based on the comparison (block 903: no), then the apparatus 1100 does not transmit the message comprising the report. [0217]^For example, in case the mobility procedure comprises a conditional primary secondary cell change (CPC) procedure, then the message may not be transmitted if the result of the measurement is above or equal to the first threshold based on the comparison. [0218]^In case the mobility procedure comprises a selective activation (SA) of cell group procedure, then the message may not be transmitted if the result of the measurement is below or equal to the second threshold based on the comparison. [0219]^FIG.10 illustrates a flow chart according to an example embodiment of a method performed by an apparatus 1200 depicted in FIG. 12. For example, the apparatus 1200 may be, or comprise, or be comprised in, a network node 104 of a radio access network, such as a master node 104A or a secondary node 104B, 104C. [0220]^Referring to FIG. 10, in block 1001, the apparatus 1200 transmits, to a user equipment 100, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment 100. [0221]^In block 1002, the apparatus 1200 receives a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment 100, wherein the report is generated and/or transmitted by the user equipment 100 based on the one or more criteria. The apparatus 1200 may receive the message from the user equipment 100 or from another network node (e.g., from a secondary node 104B or 104C). [0222]^ The one or more criteria may comprise at least one of a first threshold or a second threshold for the time between the at least two consecutive primary secondary cell changes. [0223]^ In case the mobility procedure comprises a conditional primary secondary cell change (CPC) procedure, then the configuration may indicate the user equipment 100 to transmit the message if the result of the measurement is below the first threshold based on the comparison. [0224]^In case the mobility procedure comprises a selective activation (SA) of cell group procedure, then the configuration may indicate the user equipment 100 to transmit the message if the result of the measurement is above the second threshold based on the comparison. [0225]^The report may comprise information indicating at least one of: a cause of the at least two consecutive primary secondary cell changes, a time stayed in a source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of the source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of a target primary secondary cell of the at least two consecutive primary secondary cell changes, or one or more radio measurements of one or more neighbor cells. [0226]^Alternatively, or additionally, the report may comprise information indicating the mobility procedure applied by the user equipment 100. [0227]^Alternatively, or additionally (e.g., in case the mobility procedure comprises SA), the report may comprise information indicating at least one of: a number of prepared candidate target primary secondary cells during the at least two consecutive primary secondary cell changes, or a number of subsequent cell changes after the at least two consecutive primary secondary cell changes. [0228]^The apparatus 1200 may transmit the report to a self-organizing network (SON) function, which may be hosted in the apparatus 1200 or in another network entity 111. [0229]^ In case the SON function is hosted in the apparatus 1200, the apparatus 1200 may increment at least one counter based on the report; and determine, based on the at least one counter, whether to change the mobility procedure applied by the user equipment 100 for a cell border associated with the at least two primary secondary cell changes. [0230]^In case the SON function is hosted in another network entity 111, the apparatus 1200 may increment at least one counter based on the report; and transmit, to the network entity 111, information indicating at least a value of the incremented at least one counter, wherein the information causes the network entity 111 (or SON function) to determine whether to change the mobility procedure applied by the user equipment 100 for a cell border associated with the at least two primary secondary cell changes. [0231]^The apparatus 1200 may receive, from the network entity 111, an indication for changing the mobility procedure applied by the user equipment 100 for the cell border. The apparatus 1200 may reconfigure the user equipment 100 accordingly. [0232]^ The blocks, related functions, and information exchanges (messages) described above by means of FIGS. 4-10 are in no absolute chronological order, and some of them may be performed simultaneously or in an order differing from the described one. Other functions can also be executed between them or within them, and other information may be sent, and/or other rules applied. Some of the blocks or part of the blocks or one or more pieces of information can also be left out or replaced by a corresponding block or part of the block or one or more pieces of information. [0233]^As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements. [0234]^FIG. 11 illustrates an example of an apparatus 1100 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 1100 may be an apparatus such as, or comprising, or comprised in, a user equipment (UE) 100, 102. The user equipment may also be called a wireless communication device, a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, a terminal device, or a user device. [0235]^ The apparatus 1100 may comprise a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. For example, the apparatus 1100 may comprise at least one processor 1110. The at least one processor 1110 interprets instructions (e.g., computer program instructions) and processes data. The at least one processor 1110 may comprise one or more programmable processors. The at least one processor 1110 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application-specific integrated circuits (ASICs). [0236]^The at least one processor 1110 is coupled to at least one memory 1120. The at least one processor is configured to read and write data to and from the at least one memory 1120. The at least one memory 1120 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non-volatile memory may be for example read-only memory (ROM), programmable read-only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non- transitory computer readable media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The at least one memory 1120 stores computer readable instructions that are executed by the at least one processor 1110 to perform one or more of the example embodiments described above. For example, non-volatile memory stores the computer readable instructions, and the at least one processor 1110 executes the instructions using volatile memory for temporary storage of data and/or instructions. The computer readable instructions may refer to computer program code. [0237]^The computer readable instructions may have been pre-stored to the at least one memory 1120 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions by the at least one processor 1110 causes the apparatus 1100 to perform one or more of the example embodiments described above. That is, the at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and/or blocks described above. [0238]^In the context of this document, a “memory” or “computer-readable media” or “computer-readable medium” may be any non-transitory media or medium or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). [0239]^The apparatus 1100 may further comprise, or be connected to, an input unit 1130. The input unit 1130 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise for example one or more temperature, motion and/or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and/or one or more touch detection units. Further, the input unit 1130 may comprise an interface to which external devices may connect to. [0240]^The apparatus 1100 may also comprise an output unit 1140. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a light emitting diode (LED) display, a liquid crystal display (LCD) and/or a liquid crystal on silicon (LCoS) display. The output unit 1140 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers. [0241]^The apparatus 1100 further comprises a connectivity unit 1150. The connectivity unit 1150 enables wireless connectivity to one or more external devices. The connectivity unit 1150 comprises at least one transmitter and at least one receiver that may be integrated to the apparatus 1100 or that the apparatus 1100 may be connected to. The at least one transmitter comprises at least one transmission antenna, and the at least one receiver comprises at least one receiving antenna. The connectivity unit 1150 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 1100. Alternatively, the wireless connectivity may be a hardwired application-specific integrated circuit (ASIC). The connectivity unit 1150 may also provide means for performing at least some of the blocks or functions of one or more example embodiments described above. The connectivity unit 1150 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to-analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units. [0242]^The processor 1110 is configured to cause the apparatus 1100 to perform the embodiments explained in FIGS.4 to 10 and the description thereof. For example, the processor 1110 causes the apparatus 1100 to receive at least one message (e.g., configuration and/or reconfiguration) of FIGS. 4 to 10 or transmit at least one message (e.g., report) via the connectivity unit 1150. In addition, the processor 1110 is configured to perform the time measurements and the comparison based on the stored parameters and/or instructions in the memory 1120 or at least one message received via the connectivity unit 1150. [0243]^ It is to be noted that the apparatus 1100 may further comprise various components not illustrated in FIG. 11. The various components may be hardware components and/or software components. [0244]^FIG. 12 illustrates an example of an apparatus 1200 comprising means for performing one or more of the example embodiments described above. For example, the apparatus 1200 may be an apparatus such as, or comprising, or comprised in, a network node 104 of a radio access network, such as a master node 104A or a secondary node 104B, 104C. [0245]^ The network node may also be referred to, for example, as a network element, a radio access network (RAN) node, a next generation radio access network (NG-RAN) node, a NodeB, an eNB, a gNB, a base transceiver station (BTS), a base station, an NR base station, a 5G base station, an access node, an access point (AP), a cell site, a relay node, a repeater, an integrated access and backhaul (IAB) node, an IAB donor node, a distributed unit (DU), a central unit (CU), a baseband unit (BBU), a radio unit (RU), a radio head, a remote radio head (RRH), or a transmission and reception point (TRP). [0246]^The apparatus 1200 may comprise, for example, a circuitry or a chipset applicable for realizing one or more of the example embodiments described above. The apparatus 1200 may be an electronic device comprising one or more electronic circuitries. The apparatus 1200 may comprise a communication control circuitry 1210 such as at least one processor, and at least one memory 1220 storing instructions 1222 which, when executed by the at least one processor, cause the apparatus 1200 to carry out one or more of the example embodiments described above. Such instructions 1222 may, for example, include computer program code (software). The at least one processor and the at least one memory storing the instructions may provide the means for providing or causing the performance of any of the methods and/or blocks described above. [0247]^The processor is coupled to the memory 1220. The processor is configured to read and write data to and from the memory 1220. The memory 1220 may comprise one or more memory units. The memory units may be volatile or non- volatile. It is to be noted that there may be one or more units of non-volatile memory and one or more units of volatile memory or, alternatively, one or more units of non- volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example random-access memory (RAM), dynamic random-access memory (DRAM) or synchronous dynamic random-access memory (SDRAM). Non- volatile memory may be for example read-only memory (ROM), programmable read- only memory (PROM), electronically erasable programmable read-only memory (EEPROM), flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The term “non- transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The memory 1220 stores computer readable instructions that are executed by the processor. For example, non-volatile memory stores the computer readable instructions, and the processor executes the instructions using volatile memory for temporary storage of data and/or instructions. [0248]^The computer readable instructions may have been pre-stored to the memory 1220 or, alternatively or additionally, they may be received, by the apparatus, via an electromagnetic carrier signal and/or may be copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes the apparatus 1200 to perform one or more of the functionalities described above. [0249]^The memory 1220 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and/or removable memory. The memory may comprise a configuration database for storing configuration data, such as a current neighbour cell list, and, in some example embodiments, structures of frames used in the detected neighbour cells. [0250]^The apparatus 1200 may further comprise or be connected to a communication interface 1230, such as a radio unit, comprising hardware and/or software for realizing communication connectivity with one or more wireless communication devices according to one or more communication protocols. The communication interface 1230 comprises at least one transmitter (Tx) and at least one receiver (Rx) that may be integrated to the apparatus 1200 or that the apparatus 1200 may be connected to. The communication interface 1230 may provide means for performing some of the blocks for one or more example embodiments described above. The communication interface 1230 may comprise one or more components, such as: power amplifier, digital front end (DFE), analog-to-digital converter (ADC), digital-to- analog converter (DAC), frequency converter, (de)modulator, and/or encoder/decoder circuitries, controlled by the corresponding controlling units. [0251]^The communication interface 1230 provides the apparatus with radio communication capabilities to communicate in the wireless communication network. The communication interface may, for example, provide a radio interface to one or more UEs 100, 102. The apparatus 1200 may further comprise or be connected to another interface towards a core network 110, such as the network coordinator apparatus or AMF, and/or to the access nodes 104, 104A, 104B, 104C of the wireless communication network. [0252]^The apparatus 1200 may further comprise a scheduler 1240 that is configured to allocate radio resources. The scheduler 1240 may be configured along with the communication control circuitry 1210 or it may be separately configured. [0253]^ It is to be noted that the apparatus 1200 may further comprise various components not illustrated in FIG. 12. The various components may be hardware components and/or software components. [0254]^As used in this application, the term “circuitry” may refer to one or more or all of the following: a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and b) combinations of hardware circuits and software, such as (as applicable): i) a combination of analog and/or digital hardware circuit(s) with software/firmware and ii) any portions of hardware processor(s) with software (including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone, to perform various functions); and c) hardware circuit(s) and/or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (for example firmware) for operation, but the software may not be present when it is not needed for operation. [0255]^This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device. [0256]^The control circuitry 1210 is configured to cause the apparatus 1200 to perform the embodiments explained in FIGS. 4 to 10 and the description thereof. For example, the control circuitry 1210 causes the apparatus 1200 to transmit at least one message (e.g., configuration and/or reconfiguration) of FIGS. 4 to 10 or receive at least one message (e.g., report) via the communication interface Tx/Rx unit 1230. In addition, the control circuitry 1210 is configured to increase or decrease the counter and/or the determination whether to change the mobility procedure based on the report received from the user equipment 100. [0257]^The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of example embodiments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chipset (for example procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art. [0258]^It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways within the scope of the claims. The embodiments are not limited to the example embodiments described above, but may vary within the scope of the claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiments.

Claims

Claims 1. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; perform a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; compare a result of the measurement with the one or more criteria; and transmit, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. 2. The apparatus according to claim 1, wherein the one or more criteria comprise at least one of a first threshold or a second threshold for the time between the at least two consecutive primary secondary cell changes. 3. The apparatus according to claim 2, wherein the mobility procedure comprises a conditional primary secondary cell change procedure, and wherein the message is transmitted if the result is below the first threshold based on the comparison. 4. The apparatus according to claim 2, wherein the mobility procedure comprises a selective activation of cell group procedure, and wherein the message is transmitted if the result is above the second threshold based on the comparison. 5. The apparatus according to any preceding claim, wherein the report comprises information indicating at least one of: a cause of the at least two consecutive primary secondary cell changes, a time stayed in a source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of the source primary secondary cell of the at least two consecutive primary secondary cell changes, an identity of a target primary secondary cell of the at least two consecutive primary secondary cell changes, or one or more radio measurements of one or more neighbor cells. 6. The apparatus according to any preceding claim, wherein the report comprises information indicating the mobility procedure applied by the apparatus. 7. The apparatus according to any preceding claim, wherein the report comprises information indicating at least one of: a number of prepared candidate target primary secondary cells during the at least two consecutive primary secondary cell changes, or a number of subsequent cell changes after the at least two consecutive primary secondary cell changes. 8. An apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receive a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. 9. The apparatus according to claim 8, further being caused to: transmit the report to a self-organizing network function. 10. The apparatus according to any of claims 8 to 9, further being caused to: increment at least one counter based on the report; and determine, based on the at least one counter, whether to change the mobility procedure applied by the user equipment for a cell border associated with the at least two consecutive primary secondary cell changes. 11. The apparatus according to any of claims 8 to 9, further being caused to: increment at least one counter based on the report; and transmit, to a network entity, information indicating at least a value of the incremented at least one counter, wherein the information causes the network entity to determine whether to change the mobility procedure applied by the user equipment for a cell border associated with the at least two consecutive primary secondary cell changes. 12. The apparatus according to claim 11, further being caused to: receive, from the network entity, an indication for changing the mobility procedure applied by the user equipment for the cell border. 13. An apparatus comprising: means for receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; means for performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; means for comparing a result of the measurement with the one or more criteria; and means for transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. 14. An apparatus comprising: means for transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and means for receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. 15. A method comprising: receiving, by an apparatus, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing, by the apparatus, a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing, by the apparatus, a result of the measurement with the one or more criteria; and transmitting, by the apparatus, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. 16. A method comprising: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria. 17. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the apparatus; performing a measurement of a time between at least two consecutive primary secondary cell changes performed according to the mobility procedure; comparing a result of the measurement with the one or more criteria; and transmitting, based on the comparison, a message comprising a report associated with the at least two consecutive primary secondary cell changes. 18. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: transmitting, to a user equipment, a configuration indicating one or more criteria for monitoring efficiency of a mobility procedure applied by the user equipment; and receiving a message comprising a report associated with at least two consecutive primary secondary cell changes performed by the user equipment, wherein the report is generated by the user equipment based on the one or more criteria.
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