Patent Description:
With the tremendous growth in the number of connected devices and the rapid increase in user/network traffic volume, various efforts have been made to improve different aspects of wireless communication for cellular wireless communication systems, such as fifth generation (<NUM>) New Radio (NR), by improving data rate, latency, reliability and mobility.

The <NUM> NR system is designed to provide flexibility and configurability to optimize the network services and types, accommodating various use cases such as enhanced Mobile Broadband (eMBB), massive Machine-Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC).

<CIT> discloses a wireless device receiving from a first base station, a radio resource control message indicating a command of a conditional handover towards a target cell of a second base station. The radio resource control message comprises: a cell identifier of the target cell; and at least one handover execution condition. The wireless device determines that at least one criteria of the at least one handover execution condition is met by the target cell of the second base station. The wireless device transmits to the first base station and in response to the determining that the at least one criteria is met, a first signal indicating a handover execution notification associated with the command of the conditional handover. The wireless device transmits to the second base station, a random access preamble via the target cell of the second base station.

However, as the demand for radio access continues to increase, there exists a need for further improvements in the art.

The problem is solved by the teachings of the independent claims.

The present disclosure is related to a method for a CPC procedure in a cellular wireless communication network.

According to an aspect of the present disclosure, a user equipment (UE) is provided for a conditional Primary Secondary Cell Group (SCG) Cell (PSCell) change (CPC) procedure. The UE includes one or more non-transitory computer-readable media containing computer-executable instructions embodied therein and at least one processor coupled to the one or more non-transitory computer-readable media. The at least one processor is configured to execute the computer-executable instructions to: transmit, to a master node, a UE capability report indicating whether the UE supports conditional reconfiguration for PSCell change and whether the UE supports conditional reconfiguration for Primary Cell (PCell) change; receive, from the master node, a conditional reconfiguration for changing from a source PSCell to a target PSCell in an SCG portion of a radio resource control (RRC) reconfiguration message, the conditional reconfiguration including a configuration of the target PSCell and an execution condition; evaluate the execution condition; apply the configuration of the target PSCell and synchronizing to the target PSCell after determining that the execution condition is satisfied; and transmit, to the master node, a response message after determining that the conditional reconfiguration is applied.

According to another aspect of the present disclosure, a method for a CPC procedure performed by a UE is provided. The method includes: transmitting, to a master node, a UE capability report indicating whether the UE supports conditional reconfiguration for PSCell change and whether the UE supports conditional reconfiguration for Primary Cell, PCell, change; receiving, from the master node, a conditional reconfiguration for changing from a source PSCell to a target PSCell in an SCG portion of an RRC reconfiguration message, the conditional reconfiguration including a configuration of the target PSCell and an execution condition; evaluating the execution condition; applying the configuration of the target PSCell and synchronizing to the target PSCell after determining that the execution condition is satisfied; and transmitting, to the master node, a response message after determining that the conditional reconfiguration is applied.

Aspects of the disclosure are best understood from the following detailed disclosure when read with the accompanying drawings. Various features are not drawn to scale. Dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations.

For the purpose of consistency and ease of understanding, like features may be identified (although, in some examples, not illustrated) by the same numerals in the drawings. However, the features in different implementations may be differed in other respects and shall not be narrowly confined to what is illustrated in the drawings.

The phrases "in one implementation," or "in some implementations," may each refer to one or more of the same or different implementations. The term "coupled" is defined as connected whether directly or indirectly through intervening components and is not necessarily limited to physical connections. The term "comprising" means "including, but not necessarily limited to" and specifically indicates open-ended inclusion or membership in the so-described combination, group, series or equivalent. The expression "at least one of A, B and C" or "at least one of the following: A, B and C" means "only A, or only B, or only C, or any combination of A, B and C.

The terms "system" and "network" may be used interchangeably. The term "and/or" is only an association relationship for describing associated objects and represents that three relationships may exist such that A and/or B may indicate that A exists alone, A and B exist at the same time, or B exists alone. The character "/" generally represents that the associated objects are in an "or" relationship.

For the purposes of explanation and non-limitation, specific details such as functional entities, techniques, protocols, and standards are set forth for providing an understanding of the present disclosure. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

Persons skilled in the art will immediately recognize that any network function(s) or algorithm(s) disclosed may be implemented by hardware, software or a combination of software and hardware. Disclosed functions may correspond to modules which may be software, hardware, firmware, or any combination thereof.

A software implementation may include computer-executable instructions stored on a computer-readable medium such as memory or other types of storage devices. One or more microprocessors or general-purpose computers with communication processing capability may be programmed with corresponding executable instructions and perform the disclosed network function(s) or algorithm(s).

The microprocessors or general-purpose computers may include Applications Specific Integrated Circuitry (ASIC), programmable logic arrays, and/or using one or more Digital Signal Processor (DSPs). Although some of the disclosed implementations are oriented to software installed and executing on computer hardware, alternative implementations implemented as firmware or as hardware or as a combination of hardware and software are well within the scope of the present disclosure. The computer readable medium includes but is not limited to Random Access Memory (RAM), Read Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory, Compact Disc Read-Only Memory (CD-ROM), magnetic cassettes, magnetic tape, magnetic disk storage, or any other equivalent medium capable of storing computer-readable instructions.

A radio communication network architecture such as a Long Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, an LTE-Advanced Pro system, or a <NUM> NR Radio Access Network (RAN) typically includes at least one base station (BS), at least one UE, and one or more optional network elements that provide connection within a network. The UE communicates with the network such as a Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial RAN (E-UTRAN), a <NUM> Core (5GC), or an internet via a RAN established by one or more BSs.

A UE may include but is not limited to a mobile station, a mobile terminal or device, or a user communication radio terminal. The UE may be a portable radio equipment that includes but is not limited to a mobile phone, a tablet, a wearable device, a sensor, a vehicle, or a Personal Digital Assistant (PDA) with wireless communication capability. The UE is configured to receive and transmit signals over an air interface to one or more cells in a RAN.

The BS may be configured to provide communication services according to at least a Radio Access Technology (RAT) such as Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM) that is often referred to as <NUM>, GSM Enhanced Data rates for GSM Evolution (EDGE) RAN (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS) that is often referred to as <NUM> based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), LTE, LTE-A, evolved LTE (eLTE) that is LTE connected to 5GC, NR (often referred to as <NUM>), and/or LTE-A Pro. However, the scope of the present disclosure is not limited to these protocols.

The BS may include but is not limited to a node B (NB) in the UMTS, an evolved node B (eNB) in LTE or LTE-A, a radio network controller (RNC) in UMTS, a BS controller (BSC) in the GSM/GERAN, a next generation (ng)-eNB in an Evolved Universal Terrestrial Radio Access (E-UTRA) BS in connection with 5GC, a next generation Node B (gNB) in the <NUM>-RAN, or any other apparatus capable of controlling radio communication and managing radio resources within a cell. The BS may serve one or more UEs via a radio interface.

Each cell (often referred to as a serving cell) provides services to serve one or more UEs within its radio coverage such that each cell schedules the downlink (DL) and optionally uplink (UL) resources to at least one UE within its radio coverage for DL and optionally UL packet transmissions. The BS can communicate with one or more UEs in the radio communication system via the plurality of cells.

A cell may allocate sidelink (SL) resources for supporting Proximity Service (ProSe) or Vehicle to Everything (V2X) service. Each cell may have overlapped coverage areas with other cells.

As previously disclosed, the frame structure for NR supports flexible configurations for accommodating various next generation (e.g., <NUM>) communication requirements such as Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC), while fulfilling high reliability, high data rate and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology in the 3rd Generation Partnership Project (3GPP) may serve as a baseline for an NR waveform. The scalable OFDM numerology such as adaptive sub-carrier spacing, channel bandwidth, and Cyclic Prefix (CP) may also be used.

When a transmission time interval (TTI) of a single NR frame includes DL transmission data, a guard period, and UL transmission data, the respective portions of the DL transmission data, the guard period, and the UL transmission data may be configured based on the network dynamics of NR. SL resources may also be provided in an NR frame to support ProSe services or V2X services.

Examples of some terms used in the present disclosure are given below.

Primary Cell (PCell): PCell is the master cell group (MCG) cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. PCell is the special cell (SpCell) of the MCG.

Primary SCG Cell (PSCell): For dual connectivity (DC) operation, PSCell is the secondary cell group (SCG) cell in which the UE performs random access when performing the Reconfiguration with Sync procedure. PSCell is the SpCell of the SCG. In some implementations, the term PSCell may refer to a Primary Secondary Cell. The term "Primary SCG Cell" and the term "Primary Secondary Cell" may be used interchangeably in the present disclosure.

Special Cell (SpCell): For DC operation the term Special Cell (SpCell) refers to the PCell of the MCG or the PSCell of the SCG, otherwise the term Special Cell refers to the PCell.

Secondary Cell (SCell): For a UE configured with carrier aggregation (CA), SCell is a cell providing additional radio resources on top of Special Cell.

Serving Cell: For a UE in RRC_CONNECTED not configured with CA/DC there is only one serving cell comprising the primary cell. For a UE in RRC_CONNECTED configured with CA/ DC the term "serving cells" is used to denote the set of cells comprising the Special Cell(s) and all secondary cells.

Master Cell Group (MCG): in MR-DC, MCG is a group of serving cells associated with the Master Node, comprising the SpCell (PCell) and optionally one or more SCells.

Master Node (MN): in MR-DC, MN is the radio access node that provides the control plane connection to the core network. It may be a Master eNB (in EN-DC), a Master ng-eNB (in NGEN-DC) or a Master gNB (in NR-DC and NE-DC).

Secondary Cell Group (SCG): in MR-DC, SCG is a group of serving cells associated with the Secondary Node, comprising of the SpCell (PSCell) and optionally one or more SCells.

Secondary Node (SN): in MR-DC, SN is the radio access node, with no control plane connection to the core network, providing additional resources to the UE. It may be an en-gNB (in EN-DC), a Secondary ng-eNB (in NE-DC) or a Secondary gNB (in NR-DC and NGEN-DC).

In a wireless communication network, such as E-UTRAN, one of the main causes of handover (HO) failure is a UE not receiving a Handover Command message from a source base station (e.g., a source eNB or a source gNB) or a serving base station (e.g., a serving eNB or a serving gNB). A conventional handover procedure is usually triggered by a measurement report from the UE. For example, when the serving cell's quality (e.g., signal strength and/or service quality) is below a preconfigured threshold and a neighboring cell's quality (e.g., signal strength and/or service quality) is above a preconfigured threshold, the UE may send a measurement report to the source base station under the serving cell based on the received measurement configurations. Upon receiving the measurement report, the source base station may send a Handover Request message to multiple target base stations (e.g., eNB or gNB) for admission control, and receive Handover Acknowledgement messages from the target base stations. The source base station may select and send a Handover Command message (which may be included in a Handover Acknowledgement message from one of the target base stations) to the UE so that the UE can connect to the target cell.

The success of the overall handover procedure depends on several factors. One of the factors is that the serving cell quality does not drop rapidly within a short period of time, which may be dominated by the latency of the backhaul (e.g., for X2/Xn/Xx interface), the processing time of target base stations, and the signaling transmission time. Unfortunately, in a real-world situation, the serving cell quality can drop very quickly within a short period of time, and the UE may not successfully receive the Handover Command message before the serving cell quality drops significantly. As a result, the UE may detect a radio link failure. Consequently, in response to the detected radio link failure, the UE may initiate a radio resource control (RRC) Connection Re-establishment procedure, which in turn leads to a considerable amount of service interruption time. In a next generation wireless network (e.g., a <NUM> NR network), with massive antenna beamforming in higher frequency bands, a serving cell quality may degrade even faster, especially when narrow beams are used to serve the UE. Blockage is another unavoidable problem in NR deployments.

The 3GPP has introduced the concept of conditional handover (CHO) to improve reliability of the overall handover procedure. The CHO procedure may be viewed as a supplementary procedure to the conventional handover procedure to help reduce the handover failure rate.

To execute a conditional reconfiguration command, a UE may evaluate the triggering condition(s) associated with the conditional reconfiguration command to determine whether one or more triggering conditions (or executions conditions) for the conditional reconfiguration command is met. When the UE determines that a triggering condition is satisfied, the UE may apply the corresponding conditional reconfiguration command to connect to the target cell. Existing measurement events (e.g., A3 and A5) may be used for determining whether a triggering condition of a conditional reconfiguration command is satisfied.

CHO may help to improve reliability of the overall handover procedure. Applying concepts similar to CHO may also be beneficial to a PSCell addition procedure, a PSCell change procedure, an SN addition procedure, or an SN change procedure for MR-DC mode, because preparation between the MN and the SN and RRC signaling to add the SN may finish in advance.

A UE may behave differently when concepts of CHO (or conditional configuration) are applied to a normal HO (e.g., PCell change) procedure or a PSCell addition/change (or SN addition/change) procedure. For example, the UE may not need to release the link to the current PCell (or MN) if the executed conditional reconfiguration command is for PSCell addition/change. Some information or guideline (e.g., by implicit manner) for the UE to determine what to do when a conditional reconfiguration command is executed may be required. In addition, the principles for applying CHO (or conditional configuration) to PCell change and the principles for applying CHO (or conditional configuration) to PSCell addition/change may be different due to different purposes. The UE behavior for different types of CHO (or conditional configuration) may need to be identified. Furthermore, some modifications for the PSCell addition procedure, the PSCell change procedure, the SN addition procedure, or the SN change procedure in MR-DC mode may be required when the CHO procedure (or the conditional reconfiguration procedure) is involved.

Therefore, implementations related to conditional PSCell addition (CPA) procedures and conditional PSCell change (CPC) procedures for intra-SN and inter-SN cases are provided in the present disclosure. Methods for a UE to determine what to do when a conditional reconfiguration command is executed and the corresponding UE behavior are also provided in the present disclosure.

A conditional reconfiguration procedure may be a reconfiguration procedure executed by the UE when one or more execution conditions (also referred to as triggering conditions) are met. There are three types of conditional reconfiguration. The first type is conditional reconfiguration for PCell change, also referred to as conditional reconfiguration for handover or conditional handover (CHO). The second type is conditional reconfiguration for PSCell change, also referred to as conditional PSCell change (CPC). The third type is conditional reconfiguration for PSCell addition, also referred to as conditional PSCell addition (CPA).

CHO may be a handover procedure that is executed by the UE when one or more handover execution conditions are met. The UE may start evaluating the execution condition(s) upon receiving the CHO configuration and may stop evaluating the execution condition(s) once the execution condition(s) is met. In some implementations, an execution condition may include, for example, A3/A5 events. In some implementations, an execution condition may consist of one or two trigger condition(s).

<FIG> illustrates a conditional handover procedure <NUM> according to an example implementation of the present disclosure. The source BS <NUM>, the target BS #<NUM><NUM>, and the target BS #<NUM><NUM> may be gNBs or any combination of other types of BSs. For example, any of the source BS <NUM>, the target BS #<NUM><NUM>, and the target BS #<NUM><NUM> may be an eNB in some implementations. An Access and Mobility Management Function (AMF) and a User Plane Function (UPF) may be used in a <NUM> system. The AMF and the UPF are not illustrated in <FIG>. The conditional handover procedure <NUM> may be an intra-AMF/UPF CHO procedure.

In action <NUM>, the AMF may provide mobility control information to the source BS <NUM>, the target BS #<NUM><NUM>, and the target BS #<NUM><NUM>. The UE <NUM> is served by the source BS <NUM>. The UE context within the source BS <NUM> may contain information regarding roaming and access restrictions which were provided either at connection establishment or at the last Tracking Area (TA) update. In action <NUM>, the source BS <NUM> may configure the UE <NUM> with a measurement configuration and the UE <NUM> may report to the source BS <NUM> according to the measurement configuration. In action <NUM>, the source BS <NUM> may decide to use CHO after receiving measurement reports from the UE <NUM>.

The source BS <NUM> may send a corresponding CHO Request message to each of the potential target BSs. The source BS <NUM> may send CHO Request message #<NUM> to the target BS #<NUM><NUM> in action <NUM>. The source BS <NUM> may also send CHO Request message #<NUM> to the target BS #<NUM><NUM> in action <NUM>.

In actions <NUM> and <NUM>, the target BS #<NUM><NUM> and the target BS #<NUM><NUM>, respectively, may perform admission control procedures. In one implementation, slice-aware admission control may be performed if the slice information is sent to the corresponding target BS. In one implementation, the target BS may reject protocol data unit (PDU) Sessions if the PDU sessions are associated with non-supported slices.

In action <NUM>, the target BS #<NUM><NUM> may send CHO Acknowledgement (Ack) message #<NUM> to the source BS <NUM> when the target BS #<NUM><NUM> accepts the CHO request from the source BS <NUM>. The CHO Ack message #<NUM> may include configuration of CHO candidate cell(s) of the target BS #<NUM><NUM>. Similarly, in action <NUM>, the target BS #<NUM><NUM> may send CHO Ack message #<NUM> to the source BS <NUM> when the target BS #<NUM><NUM> accepts the CHO request from the source BS <NUM>. The CHO Ack message #<NUM> may include configuration of CHO candidate cell(s) of the target BS #<NUM><NUM>.

The source BS <NUM> may send an RRC Reconfiguration message to the UE <NUM> in action <NUM>. The RRC Reconfiguration message may include a CHO configuration, such as at least one CHO candidate cell and at least one CHO execution condition. The UE <NUM> may send an RRC Reconfiguration Complete message to the source BS <NUM> in action <NUM>.

The UE <NUM> may maintain connection with the source BS <NUM> after receiving CHO configuration. In action <NUM>, the UE <NUM> may start evaluating the CHO execution conditions for the candidate cell(s). If at least one CHO candidate cell (e.g., a candidate cell of the target BS #<NUM><NUM>) satisfies the corresponding CHO execution condition, the UE may detach from the source BS, apply the stored corresponding configuration for the selected candidate cell, and synchronize to that candidate cell.

In action <NUM>, the UE <NUM> may synchronize to the target cell and may complete the CHO procedure by sending an RRC Reconfiguration Complete message to the target BS #<NUM><NUM>. In some implementations, data forwarding and/or path switch procedure may be performed after action <NUM>.

In some implementations, a conditional reconfiguration command (e.g., an RRC Reconfiguration message containing conditional reconfiguration, such as including configuration(s) of candidate cell(s) and execution condition(s)) may be associated with an indicator (or related information) to indicate that the conditional reconfiguration command is for normal HO (e.g., PCell change), PSCell addition/change, or intra-SN PSCell change, or inter-SN PSCell change.

In some implementations, a conditional reconfiguration command including configuration(s) of candidate cell(s) and execution condition(s)) is included in an MCG portion/part of an RRC Reconfiguration message or an SCG portion/part (e.g., in the container) of an RRC Reconfiguration message. In some implementations, a conditional reconfiguration command in the MCG portion/part of the RRC Reconfiguration message may imply/indicate that the conditional reconfiguration command is for normal HO (e.g., PCell change). A conditional reconfiguration command in the SCG portion/part of the RRC Reconfiguration message (e.g., in a container for SCG or in mrdc-SecondaryCellGroup Information Element) implies/indicates that the conditional reconfiguration command is for PSCell addition/change, intra-SN PSCell change, and/or inter-SN PSCell change. Note that a conditional reconfiguration command is in the form of an RRC Reconfiguration message. The terms "MCG part" and "MCG portion" may be used interchangeably in the present disclosure. Likewise, the terms "SCG part" and "SCG portion" may be used interchangeably in the present disclosure.

In some implementations, a cell list with target cell identifiers (IDs) (or the corresponding physical cell ID (PCI)) may be associated with conditional reconfiguration for HO or conditional reconfiguration for PSCell addition/change in a conditional reconfiguration command regardless of whether the conditional reconfiguration command is received from MCG or SCG.

In some implementations, an execution condition may be defined by a measurement ID (or a measure ID/measID) that identifies a measurement configuration. In some implementations, if a conditional reconfiguration command includes an execution condition defined by a measurement ID and the measurement ID is associated with a report configuration of an A3 event with the PCell as the target, the conditional reconfiguration command may be considered as a CHO (or conditional PCell change). If a conditional reconfiguration command includes an execution condition defined by a measurement ID and the measurement ID is associated with a report configuration of an A3 event with the PSCell as the target, the conditional reconfiguration command may be considered as a CPA or CPC. In some implementations, if a conditional reconfiguration command includes an execution condition defined by a measurement ID and the measurement ID is associated with a report configuration of an A5 event with the PCell as the target, the conditional reconfiguration command may be considered as a CHO. If a conditional reconfiguration command includes an execution condition defined by a measurement ID and the measurement ID is associated with a report configuration of an A5 event with the PSCell as the target, the conditional reconfiguration command may be considered as CPA or CPC.

In some implementations, if an associated execution condition of a conditional reconfiguration command is set by an MN, the conditional reconfiguration command may be regarded as a CHO or conditional PCell change. In some implementations, if an associated execution condition of a conditional reconfiguration command is set by an SN, the conditional reconfiguration command may be regarded as a CPA or CPC, such as an intra-SN PSCell change.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may not send a response/bye message to the PCell (or the MN). The response/bye message may be used to notify the execution of the conditional reconfiguration command.

It should be noted that "a conditional reconfiguration command is executed" may mean that "a conditional reconfiguration that is associated with the conditional reconfiguration command is applied" in the present disclosure. The following expressions "a conditional configuration command is executed," "a conditional configuration command is applied," "a conditional configuration is executed," and "a conditional reconfiguration is applied" may be used interchangeably in the present disclosure. Moreover, the expression "a conditional reconfiguration command is executed" used in the present disclosure may mean "the conditional reconfiguration command is being executed" or "the conditional reconfiguration command has been executed. " Likewise, the expression "a conditional reconfiguration is applied" used in the present disclosure may mean "the conditional reconfiguration is being applied" or "the conditional reconfiguration has been applied.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may release the link to the PSCell (or the MN). In one implementation, the UE may release the link after the conditional reconfiguration command (or the CHO procedure) is successfully executed.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may release the (stored) conditional reconfiguration command(s) after the conditional reconfiguration command is successfully executed. In one implementation, the UE may release the (stored) conditional reconfiguration command(s) after the UE sends a complete message to the target cell.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may stop evaluating the triggering condition of other candidate cell(s) during execution of the conditional reconfiguration for PCell change.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may stop evaluating the triggering condition(s) of conditional reconfiguration for PSCell addition/change.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may continue evaluating the triggering condition(s) of conditional reconfiguration for PSCell addition/change.

In some implementations, if a conditional reconfiguration command for PCell change is executed (e.g., an associated execution condition is satisfied) by a UE, a network (NW) command may indicate whether to continue evaluating the triggering condition(s) of conditional reconfiguration for PSCell addition/change.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) or the associated conditional reconfiguration is applied by a UE, the UE may send a response/bye message to the PCell (or the MN). The response/bye message may be used to notify the execution of the conditional reconfiguration command. In some implementations, the response/bye message may include information of at least one of the cell ID of the target PSCell, the target SN, and the conditional reconfiguration command ID, but not limited thereto. In some implementations, when receiving the response/bye message, the PCell (or the MN) may release the source SN, if required.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) or the associated conditional reconfiguration is applied by a UE, the UE may keep the link to the PCell (or the MN). In some implementation, a conditional reconfiguration command may be associated with a conditional reconfiguration command ID.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may send a response/bye message to the source PSCell (or the source SN). For example, if SRB3 is configured, the UE may send a response/bye message to the source PSCell (or the source SN) via SRB3 if the conditional reconfiguration command for PSCell addition/change is executed. The response/bye message may be used to notify the execution of the conditional reconfiguration command. In some implementations, the response/bye message may include information of at least one of the cell ID of the target PSCell, the target SN, and the conditional reconfiguration command ID, but not limited thereto. In some implementations, when receiving the response/bye message, the source PSCell (or the source SN) may inform the MN, if required. In some implementations, when receiving the response/bye message, the source PSCell (or the source SN) may release the UE context.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may keep the link to the source PSCell (or the source SN). In some implementations, the UE may release the link to the source PSCell (or the source SN) based on a NW command.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) or the associated conditional reconfiguration is applied by a UE, the UE may release the (stored) conditional reconfiguration command(s) for PSCell addition/change after the conditional reconfiguration command (or the corresponding CPC/CPA procedure) is successfully executed. In one implementation, the conditional reconfiguration command (or the corresponding CPC/CPA procedure) is successfully executed when the UE sends a complete message to the target cell. For example, the UE may send the complete message to the target cell via SRB3 if SRB3 is configured. For example, if SRB3 is not configured, the UE may send the complete message embedded in RRC signaling via SRB <NUM> to the MN first, then the MN may deliver the embedded complete message to the target cell (or the associated target SN).

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may keep the (stored) conditional reconfiguration command(s) for PCell change after the conditional reconfiguration command (or the corresponding CPC/CPA procedure) is successfully executed. In one implementation, the conditional reconfiguration command (or the corresponding CPC/CPA procedure) is successfully executed when the UE sends a complete message to the target cell.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may release the (stored) conditional reconfiguration command(s) for PCell change after the target PSCell (or target SN or source MN) sends a NW command (e.g., a new conditional reconfiguration command or a reconfiguration message) from the target SN to the UE.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may release all the (stored) conditional reconfiguration command(s) after the conditional reconfiguration command for PSCell addition/change (or the corresponding CPC/CPA procedure) is successfully executed regardless of the types/purposes of the (stored) conditional reconfiguration command(s). In one implementation, the conditional reconfiguration command is successfully executed when the UE sends a complete message to the target cell.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may continue evaluating the triggering condition(s) of conditional reconfiguration for PCell change.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may stop evaluating the triggering condition(s) of conditional reconfiguration for PCell change.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed/is being executed/has been executed (e.g., an associated execution condition is satisfied or PSCell change is triggered) or the associated conditional reconfiguration is applied/is being applied/has been applied by a UE, the UE may stop evaluating the triggering condition(s) of other candidate PSCell(s) for PSCell addition/change.

In some implementations, if a conditional reconfiguration command for PSCell addition/change is executed (e.g., an associated execution condition is satisfied) by a UE, the UE may continue evaluating the triggering condition(s) of other candidate cell(s) for PSCell addition/change.

In some implementations, the previously disclosed UE behavior (if a conditional reconfiguration command for PSCell addition/change is executed) may be optionally applied based on the channel quality of MN. For example, if the cell level quality of MN is higher than a threshold, the UE may stop evaluating the triggering condition(s) of other candidate cell(s) for PSCell addition/change.

In some implementations, a UE may release the stored conditional reconfiguration command for PSCell addition/change by a NW command (e.g., via a reconfiguration). The UE may not autonomously release any stored conditional reconfiguration command(s) for PSCell addition/change even if a normal HO (e.g., PCell change) is completed. The UE may not autonomously release any stored conditional reconfiguration command(s) for PSCell addition/change even if a PSCell addition/change is completed.

In some implementations, a conditional reconfiguration command for PCell change may contain configuration(s) of CHO candidate cell(s) generated by candidate base station(s) and execution condition(s) generated by source base station(s). In some implementations, upon executing a conditional reconfiguration command for PCell change, a UE may not monitor the source cell. In some implementations, upon executing a conditional reconfiguration command for PCell change, a UE may not monitor the source PCell. In some implementations, upon executing a conditional reconfiguration command for PCell change, a UE may not monitor the serving cell(s) or the secondary cells. In some implementations, an execution condition of a conditional reconfiguration command for PCell change may include, for example A3/A5 measurement events. Note that an A3 event is for measuring if the quality of a neighbor cell is higher than the quality of SpCell by an offset amount. Event A5 is for measuring if the quality of SpCell is lower than an absolute threshold #<NUM> and the quality of a neighbor cell is higher than another absolute threshold #<NUM>. The A3 event and the A5 event may be with reference to TS <NUM>.

In some implementations, a UE may maintain connection with a source base station (e.g., MN and/or SN, if already in MR-DC mode) after receiving conditional reconfiguration command(s) (or CHO configurations) for PCell change and may start evaluating execution conditions for the candidate cell(s). If at least one candidate cell satisfies the corresponding execution condition and the candidate cell is for PCell change, the UE may detach from the source base station, apply the stored corresponding configuration for the selected candidate cell, and synchronize to that candidate cell.

In some implementations, a conditional reconfiguration command for PSCell addition/change may contain configuration(s) of candidate cell(s) generated by candidate base station(s) (e.g., candidate SN(s)) and execution condition(s) generated by an MN. In some implementations, a conditional reconfiguration command for PSCell addition/change may contain configuration(s) of candidate cell(s) generated by candidate base station(s) (e.g., candidate SN(s)) and execution condition(s) generated by an MN or an SN (e.g., the UE is already in MR-DC mode).

In some implementations, a source SN may decide to use conditional reconfiguration for PSCell addition/change (e.g., based on the received measurement results or the cell loading). In some implementations, a source MN may decide to use conditional reconfiguration for PCell change, conditional reconfiguration for PSCell addition/change, or both. For example, for an SN-initiated SN change procedure, the source SN may provide the associated execution condition(s) for a conditional reconfiguration command. In some implementations, upon executing a conditional configuration command for PSCell addition/change, the UE may keep monitoring the source cell.

In some implementations, an execution condition of a conditional reconfiguration command for PSCell addition/change may include, for example, A3/A5 measurement events or, for example, a B1 measurement event. In some implementations, an execution condition of a conditional reconfiguration command for PSCell addition/change may include, for example, a B1 measurement event. In some implementations, an execution condition of a conditional reconfiguration command for PSCell change may consist of A3/A5 measurement. Note that the B1 event is for measuring if the quality of an inter-RAT neighboring cell is higher than a threshold. For example, for a conditional reconfiguration for inter-SN PSCell change, the MN may configure an execution condition related to a B1 event together with a configuration of a candidate cell(s) generated by a candidate SN.

In some implementations, a UE may maintain connection with a source base station (e.g., MN and/or SN, if already in MR-DC mode) after receiving conditional reconfiguration for PSCell addition/change and may start evaluating execution conditions for the candidate cell(s). If at least one candidate cell satisfies the corresponding execution condition and the candidate cell is for PSCell addition/change, the UE may not detach from the source base station (e.g., MN). The UE may apply the stored corresponding configuration for the selected candidate cell and may synchronize to that candidate cell for the corresponding PSCell addition/change procedure.

In some implementations, a UE may transmit a UE capability report to the NW (e.g., the MN) to indicate that the UE supports the conditional reconfiguration. The UE capability report indicates that the UE supports both conditional reconfiguration for PCell change and conditional reconfiguration for PSCell addition/change. In some implementations, a UE may transmit a UE capability report to the NW (e.g., the MN) to indicate that the UE supports the conditional reconfiguration for PCell change. The UE may transmit another UE capability report to the NW (e.g., the MN) to indicate that the UE supports the conditional reconfiguration for PSCell addition/change.

In some implementations, a UE may transmit a UE capability report to the NW to indicate that the UE supports the conditional reconfiguration on LTE (or E-UTRA). This capability may indicate that the UE supports both conditional reconfiguration for PCell change and conditional reconfiguration for PSCell addition/change on LTE (or E-UTRA) (e.g., for LTE DC mode). In some implementations, the UE capability report to the NW may be transmitted in an E-UTRA capability container. In some implementations, a UE may transmit a UE capability report to the NW to indicate that the UE supports conditional reconfiguration for PCell change on LTE (or E-UTRA) and may transmit another UE capability report to the NW to indicate that the UE supports conditional reconfiguration for PSCell addition/change on LTE (or E-UTRA).

In the present invention, a UE may transmit a UE capability report to the NW to indicate that the UE supports the conditional reconfiguration on NR. This capability indicates that the UE supports both conditional reconfiguration for PCell change and conditional reconfiguration for PSCell addition/change on NR (e.g., for NR-NR DC mode). In some implementations, the UE capability report to the NW may be transmitted in an NR capability container. In some implementations, a UE may transmit a UE capability report to the NW to indicate that the UE supports conditional reconfiguration for PCell change on NR and may transmit another UE capability report to the NW to indicate that the UE supports conditional reconfiguration for PSCell addition/change on NR.

In some implementations, the MN may forward the UE capability report that indicates support of the conditional reconfiguration to the SN.

In some implementations, a UE may transmit a UE capability report to the NW to indicate that the UE supports SN addition/change for a different RAT by using the conditional reconfiguration. For example, the UE may transmit the UE capability report to the LTE MN to indicate that the UE supports to add an NR SN by using conditional reconfiguration or the UE supports to change an NR SN by using conditional reconfiguration. For example, the UE may transmit the UE capability report to the NR MN to indicate that the UE supports to add an LTE SN by using conditional reconfiguration or the UE supports to change an LTE SN by using conditional reconfiguration. In some implementations, the UE may report different UE capabilities for SN addition/change in different MR-DC modes (e.g., EN-DC, NGEN-DC, or NE-DC), respectively.

An SN change procedure without CPC may be initiated either by an MN or an SN. The SN change procedure may be used to transfer a UE context from a source SN to a target SN and change the SCG configuration in the UE from one SN to another SN (i.e., applying the SCG configuration from the target SN). The SN Change procedure without CPC may always involve signaling over an MCG signaling radio bearer (SRB) towards the UE.

In some implementations, for MN-initiated inter-SN CPC (e.g., adopting CPC for SN change), the MN may not initiate a release of the source SN resources including a cause indicating SCG mobility even if an allocation of the target SN resources is successful. In one implementation, the MN may not send the source SN a Release Request message before the MN-initiated inter-SN CPC is successfully executed.

In some implementations, if a stored conditional reconfiguration command for PSCell change (or SN Change) is executed, the UE may send a response/bye message to the PCell (or the MN). After receiving the response/bye message from the UE, the MN may initiate a release of the source SN (e.g., by sending an SN Release Request message). After receiving the response/bye message from the UE, the MN may notify the target SN that the conditional reconfiguration command is executed with specific information (e.g., the UE ID, target cell ID, information related to the target SN, the executed conditional reconfiguration command, or indication/information of conditional SN change, but not limited thereto). After receiving the response/bye message from the UE, the MN may forward the SN status (e.g., provided by the source SN) and/or the data (e.g., if there are some SN-terminated bearers on the source SN) to the target SN.

<FIG> illustrates an MN-initiated inter-SN CPC procedure <NUM> according to an example implementation of the present disclosure. A UPF and an AMF may be involved if the MN-initiated inter-SN CPC is used in MR-DC with 5GC. The UPF and the AMF are not illustrated in <FIG>. For the case of MR-DC with EPC (e.g., EN-DC mode), the UPF may be replaced by a Serving Gateway (S-GW) and the AMF may be replaced by a Mobility Management Entity (MME).

In action <NUM>, the MN <NUM> may decide to initiate an inter-SN CPC procedure (also referred to as conditional reconfiguration for SN change). The inter-SN CPC procedure may cause the UE <NUM> to change from a PSCell in the source SN <NUM> to another PSCell in the target SN <NUM>. In some implementations, the MN <NUM> may configure the UE <NUM> with measurement procedures (e.g., configuring a measurement configuration) and the UE <NUM> may provide measurement reports according to the measurement configuration. Based on the measurement reports received from the UE <NUM>, the MN <NUM> may decide to use conditional reconfiguration for normal handover or conditional reconfiguration for SN change.

In action <NUM>, the MN <NUM> may initiate the SN change by requesting the target SN <NUM> to allocate resources for the UE <NUM> via an SN Addition procedure. In some implementations, the MN <NUM> may include measurement results related to the target SN <NUM> in the SN Addition Request message in action <NUM>. In some implementations, the SN Addition Request message in action <NUM> may include related information to indicate that the SN addition request is a conditional SN change request. In some implementation, if data forwarding is required, the target SN <NUM> may provide data forwarding addresses to the MN <NUM>. In some implementations, the target SN <NUM> may include the indication to indicate whether to apply the full RRC configuration or to apply the delta RRC configuration.

In action <NUM>, the target SN <NUM> may send an SN Addition Request Acknowledge message back to the MN <NUM> (e.g., if the request passes the Admission control of the target SN <NUM>). In some implementations, the SN Addition Request Acknowledge message may include configuration(s) of candidate cells for the conditional reconfiguration for inter-SN CPC.

In action <NUM>, the MN <NUM> may send to the UE <NUM> an RRC Reconfiguration message that includes one or more conditional reconfiguration command(s). Each conditional reconfiguration command may include the configuration(s) of the candidate cell(s) (e.g., candidate target PSCells) and the associated execution condition(s).

In action <NUM>, the UE <NUM> may send an RRC Reconfiguration Complete message to the MN <NUM>.

In action <NUM>, if the RRC connection reconfiguration procedure is successful, the MN <NUM> may inform the target SN <NUM> via an SN Reconfiguration Complete message, which may include an SN RRC response message for the target SN <NUM>, if received from the UE <NUM>. In some other implementations, if the RRC connection reconfiguration procedure is successful, the MN <NUM> may not inform the target SN <NUM> via an SN Reconfiguration Complete message with the SN RRC response message for the target SN <NUM> included, if received from the UE <NUM>.

In some implementations, the UE <NUM> may maintain connection with MN <NUM> after receiving conditional reconfiguration command(s) in action <NUM>. In action <NUM>, the UE <NUM> may start evaluating the execution conditions for the candidate cell(s). If one candidate cell satisfies the corresponding execution condition and this candidate cell is for the purpose of SN change, the UE <NUM> may not detach from the MN <NUM>. The UE <NUM> may apply the stored corresponding configuration for the selected candidate cell and may synchronize to that candidate cell.

In action <NUM>, the UE <NUM> may send a response message (e.g., an Execution Notification message) to inform the MN <NUM> that the conditional reconfiguration command is executed/applied. For example, the UE <NUM> may send the Execution Notification message to inform the MN <NUM> that the conditional reconfiguration command is executed after the inter-SN CPC procedure is completed. In one implementation, the UE <NUM> may send the Execution Notification message to inform the MN <NUM> that the conditional reconfiguration command is executed before the inter-SN CPC procedure is completed.

In action <NUM>, after receiving the Execution Notification message from the UE <NUM>, the MN <NUM> may send an SN Release Notification message to the source SN <NUM>. In some implementations, the SN Release Notification message may include a cause indicating SCG Mobility. In some implementations, the SN Release Notification message may include a cause indicating conditional SCG Mobility. In some implementations, the source SN <NUM> may not reject the release. For example, the source SN <NUM> may reject the release if the cause indicates normal SCG Mobility. The source SN <NUM> may not reject the release if the cause indicates conditional SCG Mobility. In some implementations, if data forwarding is required, the MN <NUM> may provide data forwarding addresses to the source SN <NUM> (e.g., in the SN Release Notification message or another message). Note that the SN Release Notification message may be the same as an SN Release Request message. In some implementations, the source SN <NUM> may reject the SN Release Request message, but the source SN <NUM> may only accept the SN Release Notification message. In some implementations, the reception of the SN Release Notification message may trigger the source SN <NUM> to stop providing user data to the UE <NUM> and may start data forwarding.

In action <NUM>, after receiving the Execution Notification message from the UE <NUM>, the MN <NUM> may send an inter-SN CPC Execution Notification message to the target SN <NUM>.

In action <NUM>, the UE <NUM> may synchronize to the target cell in the target SN <NUM>. In one implementation, the UE <NUM> may complete the inter-SN CPC procedure by sending an RRC Reconfiguration Complete message to target SN <NUM>.

In some implementations, data forwarding and/or path switch procedure may be performed to complete the SN change procedure. In some implementations, for SN terminated bearers using Radio Link Control (RLC) Acknowledged Mode (AM), the source SN <NUM> may send the SN Status Transfer (e.g., after receiving an SN Release Notification message or an SN Release Request message) to the MN <NUM>. The MN <NUM> may then send the SN Status Transfer to the target SN <NUM>. In some implementations, the source SN <NUM> may send to the MN <NUM> the Secondary RAT Data Usage Report message, which may include data volumes delivered to and received from the UE <NUM> (e.g., after receiving an SN Release Notification message or an SN Release Request message). In some implementations, if the user plane resource configuration is terminated at the source SN <NUM>, a path update procedure (or path switch procedure) may be triggered by the MN <NUM> (e.g., after receiving an execution notification message). In some implementations, the MN <NUM> may send a UE Context Release to the source SN <NUM> (e.g., after the path switch procedure is completed) such that the source SN <NUM> may release radio and control plane related resource associated with the UE context. Note that any ongoing data forwarding may continue.

<FIG> illustrates an MN-initiated inter-SN CPC procedure <NUM> according to another example implementation of the present disclosure. Actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may correspond to actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in <FIG>, respectively. In some implementations, if a stored conditional reconfiguration command for PSCell change (or SN change) is executed, the UE <NUM> may not send a response/bye message to the PCell (or the MN <NUM>).

In action <NUM>, the UE <NUM> may synchronize to the target cell and may complete the conditional SN change procedure by sending an RRC Reconfiguration Complete message to the target SN <NUM>. In some implementations, the RRC Reconfiguration Complete message may include specific information (e.g., the UE ID, target cell ID, information related to the target SN <NUM>, the executed conditional reconfiguration command (ID), or indication/information of condition SN change, but not limited thereto) to indicate to the target SN <NUM> which related conditional reconfiguration command is executed.

After receiving the complete message (e.g., RRC Reconfiguration Complete message) from the UE <NUM>, the target SN <NUM> may send a notification message (e.g., an inter-SN CPC Execution Notification message) to the MN <NUM> in action <NUM>. The notification message may indicate the execution of the conditional reconfiguration command. Some information may be included in the notification message, e.g., the UE ID, target cell ID, information related to the target SN <NUM>, the executed conditional reconfiguration command (ID), or indication/information of the condition SN change, but not limited thereto.

In some implementations, when receiving the notification message related to the execution of the conditional reconfiguration command from the target SN <NUM>, the MN <NUM> may initiate a release of the source SN <NUM> in action <NUM>. In some implementations, when receiving the notification message related to the execution of the conditional reconfiguration command, the MN <NUM> may forward the SN status (e.g., provided by the source SN <NUM>) and/or the data (e.g., if there are some SN-terminated bearers on the source SN <NUM>) to the target SN <NUM>.

In some implementations, when receiving the notification message (e.g., inter-SN CPC Execution Notification message) from the target SN <NUM>, the MN <NUM> may send an SN Release Notification message to the source SN <NUM> in action <NUM>. The SN Release Notification message may include a cause indicating SCG Mobility. In some implementations, the SN Release Notification message may include a cause indicating conditional SCG Mobility. In some implementations, the source SN <NUM> may not reject the release. For example, the source SN <NUM> may reject the release if the cause indicates normal SCG Mobility. The source SN <NUM> may not reject the release if the cause indicates conditional SCG Mobility.

In some implementations, if data forwarding is required, the MN <NUM> may provide data forwarding addresses to the source SN <NUM> (e.g., within the SN Release Notification message or other messages). Note that the SN Release Notification message may be the same as an SN Release Request message. In some implementation, the source SN <NUM> may reject the SN Release Request message, but the source SN <NUM> may only accept the SN Release Notification message.

<FIG> illustrates an SN-initiated inter-SN CPC procedure <NUM> according to an example implementation of the present disclosure. In some implementations, for SN-initiated inter-SN CPC (or SN change), the MN <NUM> may not initiate a release of resources of the source SN <NUM> including a cause indicating SCG mobility (e.g., not sending the source SN a change confirm message) even if an allocation of resources of the target SN <NUM> is successful. In one implementation, the MN <NUM> may not send the source SN <NUM> a change confirm Request message before the SN-initiated inter-SN CPC is successfully executed.

In action <NUM>, the source SN <NUM> may decide to use conditional reconfiguration for inter-SN PSCell change (or SN change). In some implementations, the source SN <NUM> (or the current serving SN) may configure the UE <NUM> with measurement procedures (e.g., configuring a measurement configuration) and the UE <NUM> may provide measurement reports according to the measurement configuration. Based on the measurement reports received from the UE <NUM>, the source SN <NUM> may decide to use conditional reconfiguration for inter-SN PSCell change (or SN Change). In some implementations, the source SN <NUM> may decide to use conditional reconfiguration and may notify the MN <NUM>. For example, the source SN <NUM> may inform the MN <NUM> to configure an MN-initiated inter-SN PSCell change. Afterward, the source SN <NUM> may configure the UE <NUM> to report (e.g., measurement results or other PSCell change related information) to the MN <NUM> and the MN <NUM> may decide to use conditional reconfiguration for inter-SN PSCell change (or SN change).

The inter-SN PSCell change procedure may cause the UE <NUM> to change from a PSCell in the source SN <NUM> to another PSCell in the target SN <NUM>. In one implementation, the UE <NUM> may receive a conditional reconfiguration for PSCell change from the MN <NUM>. The conditional reconfiguration for PSCell change may include a configuration of a target PSCell and an execution condition. In one implementation, the configuration of the target PSCell in the conditional reconfiguration for PSCell change may be generated by the target SN <NUM>. In one implementation, the execution condition in the conditional reconfiguration for PSCell change may be generated by the source SN <NUM>.

Actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may correspond to actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in <FIG>, respectively. In action <NUM>, the source SN <NUM> may initiate the SN change procedure by sending an SN Change Required message, which may include a candidate target node ID, the SCG configuration (to support delta configuration), and measurement results related to the target SN <NUM>. In some implementations, the SN Change Required message may include related information to indicate that the SN change request is a conditional SN change request.

<FIG> illustrates an SN-initiated inter-SN CPC procedure <NUM> according to another example implementation of the present disclosure. In action <NUM>, the source SN <NUM> may decide to use conditional reconfiguration for inter-SN PSCell change (or SN change). In some implementations, the source SN <NUM> (or the current serving SN) may configure the UE <NUM> with measurement procedures and the UE <NUM> may provide measurement reports according to the configured measurement procedures. Based on the measurement reports received from the UE <NUM>, the source SN <NUM> may decide to use conditional reconfiguration for inter-SN PSCell change (or SN Change). For example, if SRB3 is configured, the source SN <NUM> may receive the measurement report from the UE <NUM> via SRB3. For example, if SRB3 is not configured, the source SN <NUM> may receive the measurement report from the UE <NUM> via SRB1.

Actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> may be corresponding to actions <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in <FIG>, respectively. In action <NUM>, the source SN <NUM> may initiate the SN change procedure by sending an SN Change Required message, which may include a candidate target node ID, the SCG configuration (to support delta configuration), and measurement results related to the target SN <NUM>. In some implementations, the SN Change Required message may include related information to indicate that the SN change request is a conditional SN change request.

In action <NUM>, the target SN <NUM> may send a notification message (e.g., an inter-SN CPC Execution Notification message) to the MN <NUM> after receiving the RRC Reconfiguration Complete message from the UE <NUM>. In some implementations, the notification message may include specific information (e.g., the UE ID, target cell ID, information related to the target SN <NUM>, the executed conditional reconfiguration command (ID), or indication/information of condition SN change, but not limited thereto).

In action <NUM>, the MN <NUM> may send an SN Release Notification message to the source SN <NUM> after receiving the notification message (e.g., inter-SN CPC Execution Notification message) from the target SN <NUM>. The SN Release Notification message may include a cause indicating SCG Mobility. In some implementations, the SN Release Notification message may include a cause indicating conditional SCG Mobility. In some implementations, the source SN <NUM> may not reject the release. For example, the source SN <NUM> may reject the release if the cause indicates normal SCG Mobility. The source SN <NUM> may not reject the release if the cause indicates conditional SCG Mobility.

<FIG> illustrates an SN addition procedure <NUM> according to an example implementation of the present disclosure. In some implementations, conditional reconfiguration for PSCell Addition/Change may be adopted for an SN Addition procedure.

In action <NUM>, the MN <NUM> may decide to use conditional reconfiguration for SN addition. In some implementations, the MN <NUM> may configure the UE <NUM> with measurement procedures and the UE <NUM> may provide measurement reports according to the configured measurement procedures. Based on the measurement reports received from the UE <NUM>, the MN <NUM> may decide to use conditional reconfiguration for normal HO or conditional reconfiguration for SN addition.

In action <NUM>, the MN <NUM> may decide to request the SN <NUM> to allocate resources for one or more specific PDU Sessions or Quality of Service (QoS) Flows, indicating QoS Flows characteristics (e.g., QoS Flow Level QoS parameters, PDU session level Transport Network Layer (TNL) address information, and PDU session level Network Slice info). The MN <NUM> may send an SN Addition Request message to the SN <NUM>. In some implementations, for bearers requiring SCG radio resources, the MN <NUM> may indicate to the SN <NUM> the requested SCG configuration information, including the entire UE capabilities and the UE capability coordination result. In some implementations, the MN <NUM> may provide the latest measurement results for the SN <NUM> to choose and configure the SCG cell(s). In some implementations, the SN Addition Request message may include related information to indicate that the SN addition request is a conditional SN addition request.

In action <NUM>, the SN <NUM> may send an SN Addition Request Acknowledge message back to the MN <NUM> (e.g., when the SN <NUM> determines that the request passes the Admission control of the SN <NUM>). In some implementations, the SN Addition Request Acknowledge message may include configuration(s) of candidate cells and/or associated execution condition(s) for the conditional reconfiguration.

In action <NUM>, the MN <NUM> may send to the UE <NUM> an RRC Reconfiguration message that includes one or more conditional reconfiguration command(s). Each conditional reconfiguration command may include configuration(s) of candidate cell(s) and execution condition(s). In action <NUM>, the UE <NUM> may send an RRC Reconfiguration Complete message to the MN <NUM>.

In action <NUM>, if the RRC connection reconfiguration procedure is successful, the MN <NUM> may inform the SN <NUM> via an SN Reconfiguration Complete message with the SN RRC response message for the SN <NUM> included, if received from the UE <NUM>. In some other implementations, if the RRC connection reconfiguration procedure is successful, the MN <NUM> may not inform the SN <NUM> via the SN Reconfiguration Complete message with the SN RRC response message for the SN <NUM> included, if received from the UE <NUM>.

In action <NUM>, the UE <NUM> may maintain connection with the MN <NUM> after receiving the conditional reconfiguration and start evaluating the execution conditions for the candidate cell(s). If one candidate cell satisfies the corresponding execution condition and this cell is for the purpose of SN addition, the UE <NUM> may not detach from the MN <NUM>. The UE <NUM> may apply the stored corresponding configuration for the selected candidate cell and may synchronize to that candidate cell.

In action <NUM>, the UE <NUM> may synchronize to the target cell and may complete the conditional SN addition procedure by sending an RRC Reconfiguration Complete message to the SN <NUM>. In some implementations, the RRC Reconfiguration Complete message may include specific information (e.g., the UE ID, target cell ID, information related to the SN <NUM>, the executed conditional reconfiguration command (ID), or indication/information of condition SN addition, but not limited thereto) to indicate to the SN <NUM> which related conditional reconfiguration command is executed.

In action <NUM>, after receiving the RRC Reconfiguration Complete message from the UE <NUM>, the SN <NUM> may send an SN Addition Execution Notification message to the MN <NUM>. In some implementations, the SN Addition Execution Notification message may include specific information (e.g., the UE ID, target cell ID, information related to the SN <NUM>, the executed conditional reconfiguration command, or indication/information of condition SN addition, but not limited thereto).

In some implementations, data forwarding and/or path switch procedure may be performed to complete the SN addition procedure. In some implementations, in case of SN terminated bearers using RLC AM, the MN <NUM> may send SN Status Transfer to the SN <NUM>. In some implementations, in case of SN terminated bearers using RLC AM, and dependent on the bearer characteristics of the respective QoS Flows, the MN <NUM> may take actions to minimize service interruption due to activation of MR-DC (Data forwarding). In some implementations, for SN terminated bearers, the update of the user plane path towards the 5GC is performed via the PDU Session Path Update procedure.

In some implementations, the SN may use an SN-initiated SN Modification Procedure (with MN involved) to trigger conditional reconfiguration for PSCell change, which may also be referred to as an intra-SN CPC procedure. In some implementations, the SN may use an SN-initiated SN Modification Procedure (via SRB1) to trigger an intra-SN CPC procedure if SRB3 is not configured.

<FIG> illustrates an SN-initiated intra-SN CPC procedure <NUM> according to an example implementation of the present disclosure. In action <NUM>, the SN <NUM> may decide to use conditional reconfiguration for intra-SN PSCell change. The intra-SN PSCell change procedure may change the PSCell in the SN <NUM> from a cell in the SN <NUM> (also referred to as the source PSCell) to another cell in the SN <NUM> (also referred to as the target PSCell). In one implementation, the UE <NUM> may receive a conditional reconfiguration for PSCell change from the MN <NUM>. The conditional reconfiguration for PSCell change may include a configuration of a target PSCell and an execution condition. In one implementation, the configuration of the target PSCell in the conditional reconfiguration for PSCell change may be generated by the SN <NUM>. The execution condition in the conditional reconfiguration for PSCell change may also be generated by the SN <NUM>.

In action <NUM>, the SN <NUM> may send to the MN <NUM> an SN Modification Required message including an SN RRC reconfiguration message, which may contain user plane resource configuration related context, other UE context related information and the new radio resource configuration of SCG. In some implementations, the MN <NUM> may initiate the SN Modification procedure that is triggered by the SN Modification Required message, e.g., when an SN security key change needs to be applied. In some implementations, the SN Modification Required message may include a conditional reconfiguration command for PSCell change (also referred to as intra-SN PSCell change). In some implementations, the conditional reconfiguration command for intra-SN PSCell change may contain configuration(s) of candidate cell(s) (e.g., candidate PSCell(s)) and execution condition(s) generated by the same SN <NUM>.

In action <NUM>, the MN <NUM> may send to the UE <NUM> an MN RRC reconfiguration message that includes the SN RRC reconfiguration message with the new SCG radio resource configuration and/or the conditional reconfiguration command(s). The MN RRC Reconfiguration message may include one or more conditional reconfiguration command(s) for PSCell change. Each conditional reconfiguration command may include configuration(s) of the candidate cell(s) and execution condition(s). The MN RRC reconfiguration message in action <NUM> may be transmitted via SRB1 to the UE <NUM>.

In action <NUM>, the UE <NUM> may send an RRC Reconfiguration Complete message to the MN <NUM>. In action <NUM>, the MN <NUM> may send a confirm message (e.g., an SN Modification Confirm message) to the SN <NUM> after receiving the RRC Reconfiguration Complete message from the UE <NUM>.

In action <NUM>, the UE <NUM> may evaluate the execution conditions for the candidate cell(s) (e.g., candidate PSCell(s)). The UE <NUM> may apply the configuration of a target cell (e.g., a target PSCell) and synchronize to the target cell (e.g., the target PSCell) after determining that the execution condition corresponding to the target cell (e.g., the target PSCell) is satisfied. In some implementations, if a conditional reconfiguration command is included in the MN RRC reconfiguration message, the UE <NUM> may start evaluating the execution condition(s) upon receiving the configuration (e.g., action <NUM>) and may stop evaluating the execution condition(s) during the execution of the conditional reconfiguration once the execution condition(s) is met. If at least one candidate cell satisfies the corresponding execution condition, the UE <NUM> may apply the stored corresponding configuration for the selected candidate cell and synchronize to the candidate cell. The UE <NUM> may not detach from the SN <NUM> when executing the conditional reconfiguration for intra-SN PSCell change. In some implementations, if a conditional reconfiguration command for intra-SN PSCell change is executed, the UE <NUM> may send a bye/response message to the SN <NUM>. For example, the UE <NUM> may send the bye/response message to inform the MN <NUM> that the conditional reconfiguration command is executed after the intra-SN CPC procedure is completed.

In one implementation, the UE <NUM> may not detach from the MN <NUM> when applying/executing the conditional reconfiguration for PSCell change. The UE <NUM> may maintain connection with the PCell in the MN <NUM>. In action <NUM>, the UE <NUM> may send a response message (e.g., an Execution Notification message) to the MN <NUM> after determining that the conditional reconfiguration for PSCell change is applied/executed. The response message in action <NUM> may be transmitted via SRB1 to the MN <NUM>.

In some implementations, a conditional reconfiguration command may be associated with an indication (or related information) to indicate that the conditional reconfiguration command is for intra-SN PSCell change. In some implementations, if a conditional reconfiguration command with an indication (or related information) to indicate that the conditional reconfiguration command is for intra-SN PSCell change is executed, the UE <NUM> may not detach from the SN <NUM>.

In some implementations, the SN may use an SN-initiated SN Modification Procedure (without MN involved) to trigger conditional reconfiguration for PSCell change, which may also be referred to as an intra-SN CPC procedure. In some implementations, the SN may use an SN-initiated SN Modification Procedure (without MN involved) to trigger an intra-SN CPC procedure if SRB3 is configured.

In some implementations, the SN may send an SN RRC reconfiguration message to the UE via SRB3. In some implementations, the SN RRC Reconfiguration message may include a conditional reconfiguration command for PSCell change (e.g., an intra-SN PSCell change). In some implementations, the conditional reconfiguration command for intra-SN PSCell change may include configuration(s) of candidate cell(s) and execution condition(s) generated by the same SN.

In some implementations, if a conditional reconfiguration command is included in the SN RRC reconfiguration message, the UE may start evaluating the execution condition upon receiving the conditional reconfiguration command, and the UE may stop evaluating the execution condition during the execution of the conditional reconfiguration command once the execution condition(s) is met. If at least one candidate cell satisfies the corresponding execution condition, the UE may apply the stored corresponding configuration for the selected candidate cell and synchronize to the selected candidate cell. The UE may not detach from the SN when executing the conditional reconfiguration command for intra-SN PSCell change. In some implementations, if a conditional reconfiguration command is executed, the UE may send a bye/response message to the SN.

In some implementations, a conditional reconfiguration command may be associated with an indication (or related information) to indicate that the conditional reconfiguration command is for intra-SN PSCell change. In some implementations, if a conditional reconfiguration command with an indication (or related information) to indicate that the conditional reconfiguration command is for intra-SN PSCell change is executed, the UE may not detach from the SN.

In some implementations, a UE may send an RRC Reconfiguration Complete message (or other RRC signaling), which may be used to inform the compliance/execution/completion of a conditional reconfiguration command (or the associated CPC/CPA procedure), to the MN when the conditional reconfiguration command is executed/applied. In some implementations, the MN may determine that a conditional reconfiguration command is executed (or the associated CPC/CPA procedure is completed) when receiving an RRC Reconfiguration Complete message (or other RRC signaling), which may be used to inform the compliance/execution/completion of the conditional reconfiguration command (or the associated CPC/CPA procedure). For example, the UE may complete the CPC/CPA procedure by sending to the MN an RRC signaling (e.g., ULInformationTransferMRDC message) that includes an embedded RRC Reconfiguration Complete message to the new target PSCell. The MN may then forward the SN RRC response message (e.g., the embedded RRC Reconfiguration Complete message), if received from the UE, to the SN by including it in the SN Modification Confirm message.

In some implementations, an RRC Reconfiguration Complete message (or other RRC signaling) may include specific information (e.g., the UE ID, target cell ID, information related to the target SN, the executed conditional reconfiguration command (ID), or indication/information of condition SN change, but not limited thereto). The MN may determine that a conditional reconfiguration command is executed based on the information included in the RRC Reconfiguration Complete message (or in the other RRC signaling).

In some implementations, when the MN receives an RRC Reconfiguration Complete message (or other RRC signaling) that indicates that a conditional reconfiguration command is executed, the MN may send an SN Change Confirm message, an SN Release Request message, or an SN Release Notification message to the source SN. In some implementations, when the MN receives an RRC Reconfiguration Complete message (or other RRC signaling) that indicates that a conditional reconfiguration command is executed, the MN may inform the target SN via an SN Reconfiguration Complete message with the included SN RRC response message for the target SN. The SN Reconfiguration Complete message or the SN RRC response message may include the information of the UE ID, the target cell ID, the executed conditional reconfiguration command (ID), or indication/information of condition SN change, but not limited thereto.

<FIG> illustrates a method <NUM> for a CPC procedure performed by a UE according to an example implementation of the present disclosure. In action <NUM>, the UE receives, from an MN, a conditional reconfiguration for changing from a source PSCell to a target PSCell in an SCG part of an RRC reconfiguration message. The conditional reconfiguration includes a configuration of the target PSCell and an execution condition. In one implementation, the conditional reconfiguration may include multiple configurations of multiple target PSCells and multiple execution conditions, each of which may be associated with one of the configurations of the target PSCells. The RRC reconfiguration message includes an MCG part and an SCG part. The MCG part may include configuration information related to the MCG and the SCG part may include configuration information related to the SCG. In the present invention, the conditional reconfiguration for changing from the source PSCell to the target PSCell may be in the SCG part of the RRC reconfiguration message. In one implementation, the RRC reconfiguration message may be transmitted from the MN to the UE via SRB1.

In one implementation, the source PSCell and the target PSCell belong to the same SN. The CPC procedure performed by the UE is an intra-SN CPC procedure. In one implementation, the configuration of the target PSCell and the execution condition may be generated by the same SN. The SN may transmit the configuration of the target PSCell and the execution condition to the MN, and then the MN may transmit the configuration of the target PSCell and the execution condition to the UE.

In one implementation, the source PSCell may belong to a source SN and the target PSCell may belong to a target SN different from the source SN. The CPC procedure performed by the UE may be an inter-SN CPC procedure. In one implementation, the configuration of the target PSCell may be generated by the target SN and the execution condition may be generated by the source SN. The source SN may transmit the execution condition to the MN and the target SN may transmit the configuration of the target PSCell to the MN. The MN may then transmit the configuration of the target PSCell and the execution condition to the UE. Alternatively, the source SN may transmit to the MN the configuration of the target PSCell generated by the target SN together with the associated execution condition(s) generated by the source SN.

In action <NUM>, the UE may evaluate the execution condition(s). In action <NUM>, the UE may apply the configuration of the target PSCell and synchronize to the target PSCell after determining that the execution condition is satisfied. In one implementation, the UE does not detach from the MN when executing the conditional reconfiguration for changing from the source PSCell to the target PSCell.

The UE may store multiple conditional reconfigurations, which may be received via different RRC messages. For example, the multiple conditional reconfigurations stored in the UE may include one or more conditional reconfigurations for handover, one or more conditional reconfigurations for PSCell change, and one or more conditional reconfigurations for PSCell addition. The one or more conditional reconfigurations for PSCell change may include the conditional reconfiguration received in action <NUM> and other conditional reconfigurations for PSCell change. In one implementation, the UE may stop evaluating all execution conditions in the other (or all) conditional reconfigurations for PSCell change stored in the UE after determining that the conditional reconfiguration for changing from the source PSCell to the target PSCell is applied/executed. In one implementation, the UE may release all conditional reconfigurations for PSCell change stored in the UE after the conditional reconfiguration for changing from the source PSCell to the target PSCell is applied/executed successfully. In one implementation, the UE may not release conditional reconfigurations for handover or PSCell addition after the conditional reconfiguration for changing from the source PSCell to the target PSCell is applied/executed successfully.

In action <NUM>, the UE may transmit, to the MN, a response message after determining that the conditional reconfiguration is applied/executed. The response message may indicate to the MN the application/execution of the conditional reconfiguration. In one implementation, the response message may be transmitted from the UE to the MN via SRB1.

In one implementation, the UE may transmit, to the MN, a UE capability report indicating that the UE supports the conditional reconfiguration for changing from the source PSCell to the target PSCell. In one implementation, the UE capability report may be transmitted before action <NUM>.

In one implementation, the RRC reconfiguration message received in action <NUM> may include an indicator that indicates whether the conditional reconfiguration is for the CPC procedure or a CHO procedure.

<FIG> illustrates a block diagram of a node <NUM> for wireless communication according to an example implementation of the present disclosure. As illustrated in <FIG>, a node <NUM> may include a transceiver <NUM>, a processor <NUM>, a memory <NUM>, one or more presentation components <NUM>, and at least one antenna <NUM>. The node <NUM> may also include a radio frequency (RF) spectrum band module, a BS communications module, a network communications module, and a system communications management module, Input / Output (I/O) ports, I/O components, and a power supply (not illustrated in <FIG>).

The node <NUM> may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node <NUM> and include both volatile and non-volatile media, and removable and non-removable media.

The computer-readable media may include computer storage media and communication media. Computer storage media may include both volatile and non-volatile media, and removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or data.

Computer storage media may include RAM, ROM, EPROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices. Computer storage media may not include a propagated data signal. Communication media may typically embody computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information delivery media.

Communication media may include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the previously listed components should also be included within the scope of computer-readable media.

The memory <NUM> may include computer-storage media in the form of volatile and/or non-volatile memory. The memory <NUM> may be removable, non-removable, or a combination thereof. Example memory may include solid-state memory, hard drives, optical-disc drives, etc. As illustrated in <FIG>, the memory <NUM> may store computer-readable, computer-executable instructions <NUM> (e.g., software codes) that are configured to cause the processor <NUM> to perform various functions disclosed herein, for example, with reference to <FIG>. Alternatively, the instructions <NUM> may not be directly executable by the processor <NUM> but be configured to cause the node <NUM> (e.g., when compiled and executed) to perform various functions disclosed herein.

The processor <NUM> (e.g., having processing circuitry) may include an intelligent hardware device, e.g., a Central Processing Unit (CPU), a microcontroller, an ASIC, etc. The processor <NUM> may include memory. The processor <NUM> may process the data <NUM> and the instructions <NUM> received from the memory <NUM>, and information transmitted and received via the transceiver <NUM>, the baseband communications module, and/or the network communications module. The processor <NUM> may also process information to be sent to the transceiver <NUM> for transmission via the antenna <NUM> to the network communications module for transmission to a core network.

Claim 1:
A method for an intra-Secondary Node, SN, conditional Primary Secondary Cell Group, SCG, Cell, PSCell, change, CPC, procedure performed by a user equipment, UE (<NUM>), the method comprising:
transmitting, to a master node, a UE capability report indicating that the UE supports conditional reconfiguration for PSCell change and conditional reconfiguration for Primary Cell, PCell, change;
receiving (<NUM>), from the master node, a radio resource control, RRC, reconfiguration message including a Master Cell Group, MCG, portion and an SCG portion, the SCG portion including a conditional reconfiguration for changing from a source PSCell to a target PSCell, the conditional reconfiguration including a configuration of the target PSCell and an execution condition;
evaluating (<NUM>) the execution condition;
applying (<NUM>) the configuration of the target PSCell and synchronizing to the target PSCell after determining that the execution condition is satisfied; and
transmitting (<NUM>), to the master node, a response message after determining that the conditional reconfiguration is applied,
wherein both the source PSCell and the target PSCell belong to a secondary node.