WO2022227046A1

WO2022227046A1 - Method, device and computer program product for wireless communication

Info

Publication number: WO2022227046A1
Application number: PCT/CN2021/091639
Authority: WO
Inventors: Mengjie ZHANG; He Huang; Jing Liu
Original assignee: Zte Corporation
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-03
Also published as: EP4256849A1; CN116897559A

Abstract

Method, device and computer program product for wireless communication are provided. A method includes: receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous-connectivity-based handover; and performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node; and maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.

Description

METHOD, DEVICE AND COMPUTER PROGRAM PRODUCT FOR WIRELESS COMMUNICATION

This document is directed generally to wireless communications.

A simultaneous-connectivity-based handover procedure can be used to reduce mobility interruption. In this handover procedure, the UE keeps simultaneous connection with the source cell and target cell until the completion of the handover procedure, e.g., releases the source cell after a successful random access to the target cell. Dual Active Protocol Stack (DAPS) handover (HO) is an example of such type of handover. The simultaneous-connectivity-based handover is presented as DAPS HO hereinafter.

However, only source and target primary cells (PCell) can be maintained during DAPS HO.The source cell releases the source secondary cell (SCell) and/or source secondary cell group (SCG) (also presented as the source SCell/SCG hereinafter) before sending the HO command to the user equipment (UE) . Besides, the target cell cannot configure the target SCell and/or the target SCG (also presented as the target SCell/SCG hereinafter) in the HO command. The release of the SCell/SCG may significantly decrease the throughput on the source link, which is harmful to the user experience of the UE.

The DAPS HO for FR2 (frequency range 2 (i.e., 24.25-52.6GHz) ) to FR2 case is not supported in some approaches since it is hard to support simultaneous reception and transmission for FR2-to-FR2 HO based on UE capability. However, reduction of the HO interruption time is still desired in FR2, especially considering cells with small sizes and frequent HO in high frequency.

In view of the above, a method for mobility enhancements to improve the mobility performance (including to improve reliability and/or reduce interruption time) for Dual Connectivity (DC) , Carrier Aggregation (CA) and/or FR2 scenarios, is provided in various embodiments of the present disclosure.

The present disclosure relates to methods, devices, and computer program products for wireless communication, which can improve reliability in the handover procedure.

One aspect of the present disclosure relates to a wireless communication method. In an embodiment, the wireless communication method includes: receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous-connectivity-based handover; and performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node; and maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.

Another aspect of the present disclosure relates to a wireless communication method. In an embodiment, the wireless communication method includes: transmitting, by a first wireless communication node, a handover command to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous-connectivity-based handover from the first wireless communication node to a second wireless communication node.

Another aspect of the present disclosure relates to a wireless communication terminal. In an embodiment, the wireless communication terminal includes a communication unit and a processor. The processor is configured for: receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous-connectivity-based handover; and performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node; and maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.

Another aspect of the present disclosure relates to a wireless communication node. In an embodiment, the wireless communication node includes a communication unit and a processor. The processor is configured for transmitting, by a first wireless communication node, a handover command to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous-connectivity-based handover from the first wireless communication node to a second wireless communication node.

Various embodiments may preferably implement the following features:

Preferably, the handover command includes at least one of: a first indication for an activation state of at least one of: a target secondary cell, SCell, or a target secondary cell group, SCG, or a first triggering condition for an activation of at least one of: a target SCell or a target SCG.

Preferably, the method further includes receiving, by a wireless communication terminal, from a first wireless communication node, a radio resource control, RRC, message, before reception of the handover command, wherein the RRC message comprises at least one of: a second indication for an activation state of at least one of: a source SCell or a source SCG, or a second triggering condition for an activation of at least one of: a source SCell or a source SCG.

Preferably, the method further includes, in response to at least one of: a reception of the handover command, or a reception of the first indication for the activation state of at least one of the target SCell or the target SCG, or a reception of the second indication for the activation state of at least one of the source SCell or the source SCG, the wireless communication terminal performs at least one of: switching, by the wireless communication terminal, the at least one of: the source SCell, the source SCG, the target SCell, or the target SCG, from an activated state to a deactivated state, a dormancy state, or a suspension state; or configuring, by the wireless communication terminal, the at least one of: the source SCell, the source SCG, the target SCell, or the target SCG, in a deactivated state, a dormancy state, or a suspension state.

switching, by the wireless communication terminal, the at least one of: the source SCell, the source SCG, the target SCell, or the target SCG, from an activated state to a deactivated state, a dormancy state, or a suspension state in response to at least one of: a reception of the handover command, or a reception of the first indication for the activation state of at least one of the target SCell or the target SCG, or a reception of the second indication for the activation state of at least one of the source SCell or the source SCG.

Preferably, the method further includes activating, by the wireless communication terminal, at least one of the target SCell or the target SCG in response to the handover procedure being completed, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormancy state or a suspended state during the handover procedure.

Preferably, the method further includes activating, by the wireless communication terminal, at least one of the target SCell or the target SCG in response to a random access to a target primary cell, PCell, being successfully completed, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormancy state or a suspended state during the handover procedure before the random access to the target PCell is completed successfully.

Preferably, the at least one of the target SCell or the target SCG is activated in response to the first triggering condition for the corresponding target SCell or the target SCG in the handover command being satisfied.

Preferably, the wireless communication terminal starts evaluating the at least one first triggering condition for at least one of the target SCell or the target SCG, in response to at least one of:a reception of the handover command, a completion of a successful random access to a target PCell, or a successful completion of the handover procedure.

Preferably, the method further includes activating, by the wireless communication terminal, at least one of the source SCell or the source SCG in response to the wireless communication terminal falling back to a source cell upon detection of a handover failure.

Preferably, the at least one of the source SCell or the source SCG is activated in response to the second triggering condition for the corresponding source SCell or source SCG being satisfied.

Preferably, the wireless communication terminal starts evaluating the at least one second triggering condition for at least one of the source SCell or the source SCG, in response to at least one of: a reception of the RRC message, or upon the wireless communication terminal falling back to the source cell.

Preferably, in response to a failure of the source SCell or the source SCG being detected during the handover procedure, the wireless communication terminal performs at least one of: suspending transmission and reception of all data radio bearers in the source SCell or the source SCG; resetting a media access control, MAC, for the source SCG; releasing a connection of the source SCell or the source SCG; or releasing a configuration of the source SCell or the source SCG.

Preferably, the method further includes deactivating or suspending, by the wireless communication terminal, the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.

Preferably, the method further includes detaching, by the wireless communication terminal, from a source cell in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.

Preferably, the method further includes transmitting, by the wireless communication terminal, an indication to a network node indicating that a total number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a calculation of a capability of the wireless communication terminal during a capability coordination procedure, wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.

Preferably, the method further includes receiving, by the wireless communication terminal, an indication from a network node indicating that a total number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a calculation of a capability of the wireless communication terminal during a capability coordination, wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.

Preferably, the method further includes transmitting, by the first wireless communication node, a radio resource control, RRC, message, before reception of the handover command, wherein the RRC message comprises at least one of: a second indication for an activation state of at least one of: a source SCell or a source SCG, or a second triggering condition for an activation of at least one of: a source SCell or a source SCG.

Preferably, the method further includes transmitting, by the first wireless communication node, an indication to the wireless communication terminal to instruct the wireless communication terminal deactivating or suspending the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.

Preferably, the method further includes transmitting, by the first wireless communication node, an indication to the wireless communication terminal to instruct the wireless communication terminal detaching from a source cell in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.

Preferably, the method further includes receiving, by the first wireless communication node, an indication from the wireless communication terminal indicating that a number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a total number of configured carriers of the wireless communication terminal during a capability coordination procedure, wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.

The exemplary embodiments disclosed herein are directed to providing features that will become readily apparent by reference to the following description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the present disclosure.

Thus, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order and/or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present disclosure. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the present disclosure is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims.

FIGs. 1a and 1b show a schematic diagram of a handover procedure according to an embodiment of the present disclosure.

FIG. 2 shows a flowchart of a wireless communication method according to an embodiment of the present disclosure.

FIG. 3 shows a flowchart of a wireless communication method according to another embodiment of the present disclosure.

FIGs. 4a and 4b show a flowchart of a wireless communication method according to another embodiment of the present disclosure.

FIGs. 5a and 5b show a flowchart of a wireless communication method according to another embodiment of the present disclosure.

FIG. 6 shows a bit string or bitmap according to an embodiment of the present disclosure.

FIG. 7 show a schematic diagram of an inter-node coordination procedure according to an embodiment of the present disclosure.

FIG. 8 show a schematic diagram of an inter-node coordination procedure according to another embodiment of the present disclosure.

FIG. 9 show a schematic diagram of an inter-node coordination procedure according to another embodiment of the present disclosure.

FIG. 10 show a schematic diagram of an inter-node coordination procedure according to another embodiment of the present disclosure.

FIG. 11 shows an example of a schematic diagram of a wireless communication terminal according to an embodiment of the present disclosure.

FIG. 12 shows an example of a schematic diagram of a wireless communication node according to an embodiment of the present disclosure.

FIG. 13 illustrates a wireless communication method according to an embodiment of the present disclosure.

FIG. 14 illustrates a wireless communication method according to another embodiment of the present disclosure.

To reduce mobility interruption, a Dual Active Protocol Stack (DAPS) based handover procedure can be used. In the DAPS based handover procedure, the UE keeps simultaneous connection with the source cell and target cell until releasing the source cell after successful random access to the target cell.

In step 1, a source node of the source cell configures the UE measurement procedures and the UE reports according to the measurement configuration. In an embodiment, the source node is a source gNodeB.

In step 2, the source node decides to handover the UE, based on a MeasurementReport and Radio Resources Management (RRM) information.

In step 3, the source node sends a Handover Request message to a target node of a target cell, which includes a DAPS indicator to indicate that a DAPS HO is requested. In an embodiment, the target node is a target gNodeB.

In step 4, Admission Control may be performed by the target node.

In step 5, the target node decides to accept the DAPS HO and sends the Handover Request Acknowledge to the source node, which includes a DAPS response indicator to indicate if the DAPS HO is accepted.

In step 6, the source node triggers a Uu handover by sending an RRCReconfiguration message to the UE. For data radio bearers (DRBs) configured with DAPS, the source node does not stop transmitting downlink packets until it receives the Handover Success message from the target node in step 9a.

In step 7 or 7a, the source node sends the Secondary Node (SN) Status Transfer or Early Status Transfer message to the target node to convey the uplink/downlink Packet Data Convergence Protocol (PDCP) SN status.

In steps 8 and 9, the UE initiates random access to the target cell and completes the RRC handover procedure by sending RRCReconfigurationComplete message to target node. In the case of DAPS HO, the UE does not detach from the source cell upon receiving the RRCReconfiguration message. Instead, the UE releases the source connection and configuration upon receiving an explicit release from the target node in step 9c.

In steps 9a and 9b, in the case of DAPS HO, the target node sends the Handover Success message to the source node to inform that the UE has successfully accessed the target cell. In return, the source node sends the SN Status Transfer message for DRBs configured with DAPS.

In step 9c, the target node sends an RRCReconfiguration message to the UE, including a DAPS source release indication to explicitly instruct the UE to release the source connection and configuration.

Aspect 1: handling of SCell/SCG during DAPS HO

If the source and/or target SCell (s) /SCG (s) (also presented as source/target SCell/SCG hereinafter) is allowed to be used during the DAPS HO, several options can be considered for the source/target SCell/SCG handling:

Option 1: the source SCell/SCG and/or the target SCell/SCG is allowed to be kept/configured in any state, e.g., the activated/deactivated/dormancy/suspension state.

Option 2: the source SCell/SCG and/or the target SCell/SCG is not allowed to be kept/configured in the activated state, i.e., can only be in the deactivated/dormancy/suspension state.

Option 3: the source SCell/SCG is released or removed and the target SCell/SCG is allowed to be kept in or configured as any state, e.g., the activated/deactivated/dormancy/suspension state.

Option 4: the source SCell/SCG can is released or removed and the target SCell/SCG is not allowed to be kept in or configured as the activated state, i.e., can only be in the deactivated/dormancy/suspension state.

If the source SCell/SCG and/or the target SCell/SCG is not allowed to be in the activated state during the DAPS HO, there are several alternatives to be considered to change or configure the source SCell/SCG state and/or the target SCell/SCG state for the UE:

Alt. 1: the network (NW) (e.g., a network node, such as a source node or a target node) explicitly configures/switches the SCell/SCG state into the deactivated/dormancy/suspension state by for example, including an indication into the RRC message (e.g., RRC Reconfiguration message) to indicate the SCell/SCG state as deactivated/dormancy/suspension state, sending MAC CE (media access control control element) or DCI (data control information) to switch the activated SCell/SCG into deactivated/dormancy/suspension state.

Alt. 2: the UE implicitly switches the source/target SCell/SCG state from activated to deactivated/dormancy/suspension, upon a reception of a DAPS HO command.

In the case that the source/target SCell/SCG is in the deactivated/dormancy/suspension state above, the UE may perform at least one of the following:

1. stopping or suspending the transmission and reception of all resource blocks (RBs) in the source/target SCell/SCG;

2. stopping monitoring physical downlink control channel (PDCCH) on the source/target SCell/PSCell;

3. stopping Channel State Information (CSI) report; or

4. switching to the dormant bandwidth part (BWP) on the source/target SCell/PSCell.

In some embodiments, for the suspension of the source SCG, the source cell (e.g., the source node of the source cell) may firstly reconfigure all SN terminated SCG bearer or SN terminated split bearer to SN terminated MCG bearer or MN terminated MCG bearer. Subsequently, the source cell may release the SCG configuration via an RRC message (e.g., RRC Reconfiguration message) to the UE. In such a case, the UE can maintain the SN SDAP (Service Data Adaptation Protocol) /PDCP (Packet Data Convergence Protocol) configuration and the SN key, and release the SCG RLC (Radio link control) , MAC, and/or PHY (physical) configuration.

Aspect 1-Example 1 (for Aspect 1-Option 1) :

In an embodiment, the target cell (e.g., the target node of the target cell) may configure or indicate the target SCell/SCG as an activated/deactivated/dormancy/suspension state in an HO command (i.e., RRC Reconfiguration message) to the UE.

Aspect 1-Example 2a (for Aspect 1-Option 2) :

In an embodiment, the source cell deactivates or suspends the source SCell/SCG via RRC signaling (e.g., an indication is included in an RRC Reconfiguration message to indicate the source SCell/SCG state as deactivated/suspension/dormancy) or MAC CE or DCI before (or in the same time with) the transmission of the HO command (i.e., RRC Reconfiguration message) to the UE.

In an embodiment, the target cell deactivates or suspends the target SCell/SCG via the HO command (e.g., an indication is included in an RRC Reconfiguration message to indicate the target SCell/SCG state as deactivated/suspension/dormancy) .

Aspect 1-Example 2b (for Aspect 1-Option 2) :

In an embodiment, upon the reception of the HO command, the UE automatically deactivates or suspends the source/target SCell/SCG, if there is any, e.g., the UE stops or suspends the UL (uplink) and/or DL (downlink) transmission and/or reception with the source/target cell via the SCell/SCG link.

Aspect 1-Example 3 (for Aspect 1-Option 3) :

In an embodiment, the source cell releases the SCell/SCG before sending the HO command, e.g., via the RRC Reconfiguration message.

In an embodiment, the target cell configures/indicates the target SCell/SCG as activated/deactivated/dormancy/suspension state in the HO command (i.e., RRC Reconfiguration message) to the UE.

Aspect 1-Example 4a (for Aspect 1-Option 4) :

In an embodiment, the target cell deactivates or suspends the target SCell/SCG via the HO command (e.g., an indication is included in the RRC Reconfiguration message to indicate the target SCell/SCG state as deactivated/suspension/dormancy) .

Aspect 1-Example 4b (for Aspect 1-Option 4) :

Aspect 2: fast activation or resumption of SCell/SCG

In an embodiment, if the SCell/SCG are in deactivated/suspended/dormancy sate during the DAPS HO, the NW or the UE may fast activate or resume SCell/SCG upon the completion of the DAPS HO or upon the UE falls back to the source cell in the case of the HO failure.

For the activation or resumption of the target SCell/SCG, there are several options that can be considered.

Option 1: upon the completion of the DAPS HO (i.e., the release of the source cell) , the UE automatically activates or resumes the target SCell/SCG.

Option 2: upon the successful completion of RA (random access) to the target PCell, the UE automatically activates or resumes the target SCell/SCG.

Option 3: the target cell configures triggering condition (s) for the SCell/SCG activation or resumption in the HO command. The UE activates or resumes the target SCell/SCG when the triggering condition is met or satisfied and (or after) the DAPS HO is completed.

Option 4: the target cell configures triggering condition (s) for SCell/SCG activation or resumption in the HO command. The UE activates or resumes the target SCell/SCG when the triggering condition is met or satisfied and (or after) the RA to the target PCell is successfully completed.

Option 5: upon the uplink data arrival on the target SCG bearer or the target SCell/SCG link, the UE automatically activates or resumes the source SCell/SCG.

Option 6: the combination of one of Options 1 to 4 and Option 5 such as a combination of

Options

1 and 5, a combination of

Options

2 and 5, a combination of

Options

3 and 5, or a combination of

Options

4 and 5 option 1 + option 5, option 2 + option 5, option 3 + option 5, option 4 + option 5) . For example, the combination of

Options

1 and 5 means that upon the completion of the DAPS HO and the uplink data arrival on the target SCG bearer or the target SCell/SCG link, the UE automatically activates or resumes the target SCell/SCG. The rest can be deduced by analogy.

Regarding the time when the UE starts evaluating triggering or activation condition (s) for the target SCell/SCG, there are several alternatives:

Alt. 1: the UE starts evaluating triggering or activation condition (s) for the target SCell/SCG upon the reception of the HO command (i.e., the RRC reconfiguration message) including the triggering or activation condition (s) .

Alt. 2: the UE starts evaluating triggering or activation condition (s) for the target SCell/SCG upon the completion of the DAPS HO (e.g., at the release of the source cell)

Alt. 3: the UE starts evaluating triggering or activation condition (s) for the target SCell/SCG upon successful completion of the RA to the target PCell (e.g., when an indication of the successful completion of the random access towards the target cell is received from lower layers) .

For activation or resumption of the source SCell/SCG, there are several options to be considered.

Option 1: upon the fall-back to the source cell, e.g., when the UE detects the HO failure (e.g., the timer T304 expiry) and the radio link failure is not detected in the source PCell, the UE automatically activate or resume the source SCell/SCG.

Option 2: the source cell configures the triggering condition (s) for the SCell/SCG activation or resumption in the RRC reconfiguration message before (or in the same time with) sending the HO command to the UE. The UE activates or resumes the source SCell/SCG when the triggering condition is met or satisfied and (or after) the UE falls back to the source cell.

Option 3: upon the fall-back to the source cell and the timing alignment (TA) timer associated with the source PSCell/SCell is still running, the UE automatically activates or resumes the source SCell/SCG.

Option 4: the combination of

Options

2 and 3. It means that upon the fall-back to the source cell and the triggering condition is met or satisfied and the timing alignment (TA) timer associated with the source PSCell/SCell is still running, the UE automatically activates or resumes the source SCell/SCG.

Option 5: upon the uplink data arrival on the source SCG bearer or the source SCell/SCG link, the UE automatically activates or resumes the source SCell/SCG.

Option 6: the combination of one of Options 1 to 4 and Option 5, such as a combination of

Options

1 and 5, a combination of

Options

2 and 5, a combination of

Options

3 and 5, or a combination of

Options

4 and 5. For example, the combination of

Options

1 and 5 means that upon upon the fall-back to the source cell and the uplink data arrival on the source SCG bearer or the source SCell/SCG link, the UE automatically activates or resumes the source SCell/SCG. The rest can be deduced by analogy.

Regarding the time when the UE starts evaluating triggering or activation condition (s) for the source SCell/SCG, there are several alternatives:

Alt. 1: the UE starts evaluating triggering or activation condition (s) for the source SCell/SCG upon the reception of the RRC message (e.g., RRC reconfiguration message) including the triggering or activation condition (s) for the source cell.

Alt. 2: the UE starts evaluating triggering or activation condition (s) for the source SCell/SCG upon the fall-back to the source (i.e. the detection of HO failure) .

In the case that the UE activates or resumes the source/target SCell/SCG, there are two alternatives:

Alt. 1: the UE initiates the random access (RA) to the source/target PSCell/SCell.

Alt. 2: the UE directly resumes the UL and/or DL transmission and/or reception with the source/target PSCell/SCell if the timing alignment (TA) timer associated with the source/target PSCell/SCell is running, e.g. transmit the UL data to the source/target PSCell/SCell.

In some embodiments, there are several alternatives that can be considered to configure as the triggering or activation condition (s) for the SCell/SCG activation or resumption:

Alt. 1: the RSRP (reference signal received power) , RSRQ (reference signal received quality) , and/or SINR (signal to interference plus noise ratio) threshold configured per cell (e.g., the PCI (Physical Cell ID) and frequency, the cell index) or per frequency;

Alt. 2: the measurement ID, linked with measurement event (e.g., the event A3, A5, A4, and/or B1, or other events below) and measurement object on the PSCell/SCell frequency;

Alt. 3: the measurement event (e.g., the event A3, A5, A4, and/or B1, or other events below) ;

Alt. 4: a threshold of the UL data volume, e.g. a threshold of the UL data volume for the SCG bearer or the split bearer.

The definition of each measurement event can be found as follows:

Event A1 (Serving cell becomes better than a threshold) ;

Event A2 (Serving cell becomes worse than a threshold) ;

Event A3 (Neighbour cell becomes offset better than SpCell (e.g., the radio link quality of neighbour cell becomes better than the radio link quality of SpCell plus the offset ) ) ;

Event A4 (Neighbour cell becomes better than a threshold) ;

Event A5 (SpCell becomes worse than a threshold1 and neighbour cell becomes better than a threshold2) ;

Event A6 (Neighbour cell becomes offset better than SCell (e.g., the radio link quality of neighbour cell becomes better than the radio link quality of SCell plus the offset ) ) ;

Event B1 (Inter RAT (Radio Access Technology) neighbor cell becomes better than a threshold) ; and

Event B2 (PCell becomes worse than a threshold1 and inter RAT neighbour cell becomes better than a threshold2) .

In some embodiments, the triggering or activation condition (s) for the target SCell/SCG can be set or configured by the target MN or/and the target SN. In some embodiments, the triggering or activation condition (s) for the source SCell/SCG can be set or configured by the source MN or/and the source SN.

Aspect 2-Example 1 (for Aspect 2-Option 1)

An exemplary example is described below with reference to FIG. 2.

S201: The UE receives the HO command (i.e. the RRC reconfiguration message) from the source cell.

In an embodiment, the source/target SCell/SCG is in the deactivated/suspended/dormancy state, if any. In an embodiment, the operations to configure or switch the SCell/SCG from the activated state into the deactivated/suspended/dormancy state can be identical or as in the embodiments in Aspect 1.

S202: The UE maintains connection with the source cell and performs a RA to the target cell, and determines whether the UE successfully completes the RA to the target cell.

S203: In the case that the UE successfully completes the RA to the target cell, upon the UE explicitly receives an indication from the target cell for releasing the source cell (also referred to as “source release indication” ) , the UE releases the source cell connection and/or the source cell configuration and automatically activates or resumes the target SCell/SCG, e.g., initiates the RA to the target PSCell/SCel or resumes the UL and/or DL transmission and/or reception with the target PSCell/SCell .

In some embodiments, the UE activates or resumes the target SCell/SCG upon the uplink data arrival on the target SCG bearer or the target SCell/SCG link and (or after) the reception of the source release indication.

S204: In the case that the UE fails to perform the RA to the target cell (i.e. the timer T304 expiry) , the UE decides whether to fall back to the source cell. If the RLF (Radio Link Failure) is not detected in the source PCell, the UE falls back to the source cell and automatically activates or resumes the source SCell/SCG, e.g., initiates the RA to the source PSCell/SCell or resumes the UL and/or DL transmission and/or reception with the source PSCell/SCell.

In some embodiments, the UE falls back to the source cell and the UE activates or resumes the source SCell/SCG if the timing alignment (TA) timer associated with the source PSCell/SCell is still running.

In some embodiments, the UE falls back to the source cell and the UE activates or resumes the source SCell/SCG upon the uplink data arrival on the source SCG bearer or the source SCell/SCG link.

In some embodiments, the UE falls back to the source cell and the UE activates or resumes the source SCell/SCG upon the uplink data arrival on the source SCG bearer or the source SCell/SCG link and the timing alignment (TA) timer associated with the source PSCell/SCell is still running.

Aspect 2-Example 1 (for Aspect 2-Option 2)

An exemplary example is described below with reference to FIG. 3.

S301 and S302: as in S201 and S202 in Aspect 2-Example 1.

S303: In the case that the UE successfully completes the RA to the target cell, the UE automatically activates or resumes the target SCell/SCG, e.g., initiates the RA to the target PSCell/SCell or resumes the UL and/or DL transmission and/or reception with the target PSCell/SCell.

In some embodiments, the UE activates or resumes the target SCell/SCG upon the uplink data arrival on the target SCG bearer or the target SCell/SCG link and (or after) the completion of the RA to the target cell.

S304: as in S204 Aspect 2-Example 1.

Aspect 2-Example 3 (for Aspect 2-Option 3)

An exemplary example is described below with reference to FIGs. 4a and 4b.

S401: The UE receives the HO command (i.e. the RRC reconfiguration message) or the RRC reconfiguration message for the source cell from the source node. The HO command may include the indication for the target SCell/SCG state (e.g., the SCG state is indicated as deactivated) , and/or the triggering condition for the target SCell/SCG activation or resumption. The RRC reconfiguration message for the source cell may include the indication for the source SCell/SCG state (e.g., the SCG state is indicated as deactivated) , and/or the triggering condition for the source SCell/SCG activation or resumption.

S402: The UE starts evaluating the triggering or activation condition for the target/source SCell/SCG.

S403: The UE maintains connection with the source cell and performs the RA to the target cell and determines whether the UE successfully complete an RA to the target cell.

S404: In the case that the UE successfully completes the RA to the target cell, upon the UE explicitly receives the indication from the target cell for releasing the source cell and the triggering or activation condition for the target SCell/SCG is met, or upon the triggering or activation condition for the target SCell/SCG is met after the UE explicitly receives the indication from the target cell for releasing the source cell, the UE automatically activates or resumes the corresponding target SCell/SCG, e.g., initiates the RA to the target PSCell/SCel or resumes the UL and/or DL transmission and/or reception with the target PSCell/SCell.

In some embodiments, the UE activates or resumes the target SCell/SCG upon the uplink data arrival on the target SCG bearer or the target SCell/SCG link and the triggering or activation condition for the target SCell/SCG is met and (or after) the reception of the source release indication.

S405: In the case that the UE fails to perform the RA to the target cell (i.e. the timer T304 expiry) , the UE decides whether to fall back to the source cell. If the RLF is not detected in the source PCell, the UE falls back to the source cell. Upon the UE falls back to the source cell and the triggering or activation condition for the source SCell/SCG is met, or upon the triggering or activation condition for the source SCell/SCG is met after the UE falls back to the source cell, the UE automatically activates or resumes the source SCell/SCG, e.g., initiates the RA to the source PSCell/SCell or resumes the UL and/or DL transmission and/or reception with the source PSCell/SCell.

In some embodiments, the UE falls back to the source cell, and the UE activates or resumes the source SCell/SCG if the timing alignment (TA) timer associated with the source PSCell/SCell is still running and the triggering or activation condition for the source SCell/SCG is met.

In some embodiments, the UE falls back to the source cell, and the UE activates or resumes the source SCell/SCG upon the uplink data arrival on the source SCG bearer or the source SCell/SCG link and the triggering or activation condition for the source SCell/SCG is met.

In some embodiments, the UE falls back to the source cell, and the UE activates or resumes the source SCell/SCG upon the uplink data arrival on the source SCG bearer or the source SCell/SCG link and the timing alignment (TA) timer associated with the source PSCell/SCell is still running and the triggering or activation condition for the source SCell/SCG is met.

Note that, in some embodiments, the UE starts evaluating the activation/triggering condition for the target SCell/SCG only after successful completion of the RA to the target cell (i.e., operation S402 is performed after operation S403) or after the reception of indication from the target cell for releasing the source cell (i.e., operation S402 is performed within operation S404) . In some embodiment, the UE starts evaluating the activation/triggering condition for the source SCell/SCG only after falling back to the source cell (i.e., operation S402 is performed within operation S405) .

Aspect 2-Example 4 (for Aspect 2-Option 4)

An exemplary example is described below with reference to FIGs. 5a and 5b.

S501-S503: as in S401-S403 in Aspect 2-Example 3.

S504: In the case that the UE successfully completes the RA to the target cell, upon the triggering or activation condition for the target SCell/SCG is met, the UE automatically activates or resumes the corresponding target SCell/SCG, e.g., initiates the RA to the target PSCell/SCel or resumes the UL and/or DL transmission and/or reception with the target PSCell/SCell.

In some embodiments, the UE activates or resumes the target SCell/SCG upon the uplink data arrival on the target SCG bearer or the target SCell/SCG link and the triggering or activation condition for the target SCell/SCG is met and (or after) the completion of RA to the target cell.

S505: as in S405 in Aspect 2-Example 3.

Note that, in some embodiments, the UE starts evaluating the activation/triggering condition for the target SCell/SCG only after successful completion of the RA to the target cell (i.e., operation S502 is performed after operation S503) . In some embodiments, the UE starts evaluating the activation/triggering condition for the source SCell/SCG only after falling back to the source cell (i.e., operation S502 is performed within operation S505) .

Note that, in some embodiments, only the source cell configures the triggering or activation condition for the SCell/SCG or only the target cell configures the triggering or activation condition for the SCell/SCG, and the UE behavior can be any combinations of the examples described above.

Aspect 3: handling SCell/SCG failure during DASP HO

In the case that the source SCell/SCG is configured or kept, if any source SCell/SCG failure (e.g., RLF or RLC failure) is detected on the source link during the DAPS HO, the UE may perform at least one of the following operations:

suspending the transmission and reception of all DRBs in the source SCell/SCG;

resetting the MAC for the source SCG;

releasing the source SCell/SCG connection; or

releasing the source SCell/SCG configuration.

In the case that the target SCell/SCG is configured or kept, if any target SCell/SCG failure (e.g., RLF or RLC failure) is detected on the target link during the DAPS HO, there are two options that can be considered for the UE:

Option 1: performing at least one of the following operations:

suspending the transmission and reception of all DRBs in the target SCell/SCG;

resetting the MAC for the target SCG;

releasing the target SCell/SCG connection; or

releasing the target SCell/SCG configuration.

Option 2: performing an SCell/SCG failure handling approach (e.g., initiating the failure information procedure to report RLC failure, or initiating the SCG failure information procedure to report the SCG RLF) .

In some embodiments, the RLC failure on the SCell may be detected in the following cases:

upon an indication from the MCG (master cell group) RLC that the maximum number of retransmissions has been reached and CA (Carrier Aggregation) duplication is configured and activated for the MCG, and for the corresponding logical channel allowedServingCells only including the SCell (s) .

In some embodiments, the RLF on the SCG may be detected in the following cases:

upon the timer T310 expires in the PSCell;

upon the timer T312 expires in the PSCell;

upon random access problem indication from the SCG MAC;

upon indication from the SCG RLC that the maximum number of retransmissions has been reached; and/or

if connected as an IAB (Integrated Access Backhaul) -node, upon BH (Backhaul) RLF indication received on BAP (Backhaul Adaptation Protocol) entity from the SCG.

Aspect 4: operations when UE capability is exceeded

In some approaches, if the SCell/SCG is activated during the DAPS HO, the UE shall maintain the DL/UL reception/transmission with all serving cells on the source link and the target link. In the case that a summation of the source cell configuration and/or scheduling and target cell configuration and/or scheduling exceeds the maximum UE capability, the UE may declare an HO failure and trigger an RRC re-establishment, which may cause long interruption time. Some optimization can be considered for such case:

Option 1: the UE automatically deactivates or suspends the source and/or target SCG/SCell, e.g., the UE suspends the UL and/or DL transmission and/or reception with the source/target PSCell/SCell, and only maintains the connection with the source PCell and the target PCell.

Option 2: the UE falls back to the normal HO, i.e., the UE detaches from the source cell, and synchronizes to the target cell.

The NW (e.g., a network node such as the source node or the target node) can send an indication to the UE to indicate whether the optimization (i.e., Options 1 or 2) above is allowed via dedicated RRC signaling (e.g., the RRC Reconfiguration message) or broadcast signaling (e.g., the system information message) .

In some embodiments, the target cell can include an indication in the HO command (i.e., the RRC reconfiguration message) to indicate that the UE can deactivate or suspend the source/target SCG/SCell if the UE capability is exceeded. In the case that the UE capability is exceeded during the DAPS HO, the UE automatically deactivates or suspends the source and/or target SCG/SCell, if any.

In some embodiments, the target cell can include an indication in the HO command (i.e., the RRC reconfiguration message) to indicate that the UE can fall back to the normal HO if the UE capability is exceeded. In the case that the UE capability is exceeded during the DAPS HO, the UE performs the normal HO, i.e., detaches from the source cell, and synchronizes to the target cell.

Aspect 5: inter-node coordination

Considering the UE may keep connections with all serving cells on both the source link and the target link during the DAPS HO, inter-node coordination/interactions may be need during the HO preparation phase to ensure the source and target cell configurations do not exceed the maximum UE capability. There are several options that can be considered for the inter-node coordination/interactions:

Option 1: The source cell indicates or sends restrictions/suggested/reference/coordination information to the target cell via the HO request message, in which the restrictions/suggested/reference/coordination information is observed by target cell during the DAPS handover.

Option 2: The target cell indicates or sends selected/used/requested information to the source cell via the HO request acknowledge message, in which the selected/used/requested information is observed by source cell during DAPS handover.

Option 3: Both Option 1 and Option 2 are adopted.

Option 4: The source cell indicates/transmits restrictions/suggested/reference/coordination information to the target cell via the HO request message. If the target cell determines to request or use another configuration, the target cell indicates or sends a requested configuration to the source cell via an Xn/X2 message (e.g. the Handover Preparation Failure message) . Subsequently, the source cell takes the requested configuration into account, and accordingly decides to update the source configuration and/or initiates a new HO preparation procedure to the target cell.

In an embodiment, the restrictions/suggested/reference/coordination information can be transmitted to the target node by one of the following alternatives:

Alt. 1: Including such information directly in an Xn/X2 message, e.g., as one information element in the Handover Request message.

Alt. 2: Including such information in an RRC message, e.g., an HandoverPreparationInformation message. The RRC message is included in the Xn/X2 message (e.g. Handover Request message) as one information element.

In an embodiment, the requested/used/selected information can be transmitted to the source node by one of the following alternatives:

Alt. 1: Including such information directly in an Xn/X2 message, e.g., as one information element in the Handover Request Acknowledge message or Handover Preparation Failure message.

Alt. 2: Include such information in an RRC message, e.g., an HandoverCommand message. The RRC message is included in the Xn/X2 message (e.g. Handover Request Acknowledge message) as one information element.

In an embodiment, the source cell can send at least one of the following configurations or information to the target cell, which is to be observed by target cell during the DAPS handover, and/or to be considered for target cell configuration:

1. The UE capability information, which is allowed to be used by the target cell or which is used by the source cell in the DAPS HO. More specifically, the UE capability information includes at least one of the following information:

1) Bandcombination (BC) information, which can be indicated as an index or a list of indices referring to band combinations in MR-DC (Multi-Radio Dual Connectivity) , CA, and/or DAPS capabilities;

2) The band entry or entries in the associated BC, which can be indicated as an index or a list of indices referring to the position of a band entry.

3) The FeatureSetUplink/FeatureSetDownlink information, which can be indicated as an index or a list of indices (e.g., FeatureSetDownlinkId, FeatureSetUplinkId) referring to the position of the FeatureSetDownlink and/or FeatureSetUplink.

4) The FeatureSetCombination information, which can be indicated as an index or a list of indices referring to a position in the FeatureSetCombination, corresponding to one FeatureSetUplink or FeatureSetDownlink for each band entry in the associated band combination.

5) The FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC information, which can be indicated as an index or a list of indices (e.g., FeatureSetDownlinkPerCC-Id, FeatureSetUplinkPerCC-Id) referring to the position of the FeatureSetDownlinkPerCC and/or FeatureSetUplinkPerCC.

2. The power coordination information, which includes at least one of the following indications:

1) The maximum total transmit power to be used by the UE in the source cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-DAPS-source.

2) The maximum total transmit power to be used by the UE in the target cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-DAPS-target.

3) The maximum total transmit power to be used by the UE in the source MCG/SCG during the DAPS handover, e.g., the parameters p-DAPS-source-MCG and/or p-DAPS-source-SCG.

4) The maximum total transmit power to be used by the UE in the target MCG/SCG during the DAPS handover, e.g., the parameters p-DAPS-target-MCG and/or p-DAPS-target-SCG.

5) The maximum total transmit power to be used by the UE in the NR (new radio) cell group across all serving cells in frequency range 1 (FR1) during the DAPS handover, e.g., the parameter p-maxNR-FR1.

6) The maximum total transmit power to be used by the UE in the NR cell group across all serving cells in FR1 that the UE can use in the source cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-maxNR-FR1-source.

7) The maximum total transmit power to be used by the UE in the NR cell group across all serving cells in FR1 that the UE can use in the target cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-maxNR-FR1-target.

8) The maximum total transmit power to be used by the UE in the NR cell group across all serving cells in frequency range 2 (FR2) during the DAPS handover, e.g., the parameter p-maxNR-FR2.

9) The maximum total transmit power to be used by the UE in the NR cell group across all serving cells in FR2 that the UE can use in the source cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-maxNR-FR2-source.

10) The maximum total transmit power to be used by the UE in the NR cell group across all serving cells in FR2 that the UE can use in the target cell group (including both MCG and SCG, if configured) during the DAPS handover, e.g., the parameter p-maxNR-FR2-target.

11) The maximum total transmit power to be used by the UE in the E-UTRA (Evolved Universal Terrestrial Radio Access) cell group, e.g., the parameter p-maxEUTRA.

12) The maximum total transmit power to be used by the UE in the E-UTRA cell group that the UE can use in the source cell group, e.g., the parameter p-maxEUTRA-source.

13) The maximum total transmit power to be used by the UE in the E-UTRA cell group that the UE can use in the target cell group, e.g., the parameter p-maxEUTRA-target.

14) The uplink power sharing mode (e.g., semi-static-mode1, semi-static-mode2, dynamic) that the UE uses in the DAPS handover, e.g., the parameter uplinkPowerSharingDAPS-Mode.

15) The uplink power sharing mode (e.g., semi-static-mode1, semi-static-mode2, dynamic) that the UE uses in FR1 during the DAPS handover, e.g., the parameter uplinkPowerSharingDAPS-Mode-FR1.

16) The uplink power sharing mode (e.g., semi-static-mode1, semi-static-mode2, dynamic) that the UE uses in FR2 during the DAPS handover, e.g., the parameter uplinkPowerSharingDAPS-Mode-FR2.

17) The maximum Toffset value the target cell is allowed to use for scheduling target transmissions, e.g., the parameter maxToffset. It’s used only in the case that the uplink power sharing mode is set to be dynamic.

3. The serving cell number/range that the target node is allowed to configure for target serving cells, which includes at least one of the following indications:

1) The range of serving cell that the target node is allowed to configure for target serving cells, e.g., the parameter servCellIndexRangeTarget, including the lower bound and the upper bound of the serving cell index.

2) The maximum number of serving cell that the target node is allowed to configure and the lower bound of the serving cell index that can be used in the target node.

4. The maximum number of cells that the target node is allowed to configure for PDCCH blind detection, e.g., the parameter pdcch-BlindDetectionTarget.

5. Measurement coordination information, which includes at least one of the following indications:

1) The maximum number of inter-frequency carriers the target cell is allowed to configure for measurements, e.g., the parameter maxMeasFreqsTarget.

2) The maximum number of allowed measurement identities that the target cell is allowed to configure for inter-frequency measurement, e.g., the parameter maxInterFreqMeasIdentitiesTarget

3) The maximum number of allowed measurement identities that the target cell is allowed to configure for intra-frequency measurement on each serving frequency, e.g., the parameter maxIntraFreqMeasIdentitiesTarget

4) The maximum number of CLI RSSI resources that the target cell is allowed to configure, e.g., the parameter maxMeasCLI-ResourceTarget

5) The maximum number of SRS resources that the target cell is allowed to configure for CLI (Cross Link Interference) measurement, e.g., the parameter maxMeasSRS-ResourceTarget

6. The power headroom (PH) information in the source cell group that is needed in the reception of the PHR (Power Headroom Report) MAC CE in the target cell group, e.g., the parameter ph-InfoSource. It may include a list of serving cell indexes in the source cell group and the power headroom types (e.g., type 1, type 2 or type 3) for the associated serving cells (e.g., the PCell and the activated SCells) , and may also include the power headroom type for the supplementary uplink carrier.

7. FR information in the source cell group, e.g., the parameter fr-InfoListSource, which contains FR information (e.g., FR1 or FR2) of the serving cells (e.g., PCell, PSCell, SCell (s) ) configured in the source cell group.

8. Resources utilization coordination information (or time domain pattern information) , which may include a bitmap or bit string to indicate whether a specific frequency and time resource is intended to be used by the source. Then, the target node assumes the resource which is not intended to be used by the source can be used for the target cell.

Note that, in some embodiments, the resources utilization coordination information can be used for a simultaneous-connectivity-based handover procedure but without simultaneous transmission to or/and reception from the source cell and the target cell, i.e. the UE can keep simultaneous connectivity with the source and target cells and perform the reception or/and transmission with the source cell and the target cell in different timing during the HO. An example of such type of handover is a TDM (Time-division multiplexing) -based DAPS HO. Such type of handover is presented as a TDM-based DAPS HO hereinafter.

In some embodiments, the source cell includes the resources utilization coordination information in the HO Request message to implicitly request the target cell to perform a TDM-based DAPS HO. In some embodiments, the target cell includes the resources utilization coordination information in the HO Request Acknowledge message to implicitly indicate or inform the source cell about the accept of TDM-based DAPS HO. In some embodiments, the target cell includes the resources utilization coordination information in the HO Request Acknowledge message to indicate or inform the source cell to use of a TDM-based DAPS HO.

In some embodiments, the source cell includes an indication in the HO Request message to indicate the request or use of a TDM-based DAPS HO. In some embodiments, the target cell includes an indication in the HO Request Acknowledge message to indicate or inform the source cell whether the target cell accepts the TDM-based DAPS HO or not.

In some embodiments, the target cell includes an indication in the HO command (i.e., RRC reconfiguration message) to indicate the UE to perform or use a TDM-based DAPS HO.

In the following paragraph, an example using UL resource coordination bit string or bitmap is provided with reference to FIG. 6.

Each position in the bit string or bitmap represents a Physical Radio Block (PRB) pair in a UL subframe. The value "0" in the bitmap indicates "the resource not intended to be used for transmission by the sending node" , and the value "1" indicates "the resource intended to be used for transmission by the sending node" , or vice versa. The bit string spans across N subframes and with a length of N*M bits. M is the PRB number in the single subframe. The bit string spans from the first PRB pair of the first represented subframe to the last PRB pair of the same subframe and then moves to the following PRBs in the following subframes in the same order. Each position is applicable only in positions corresponding to UL subframes.

In some embodiments, the same configuration may also apply to DL resource coordination, where each position is applicable only in positions corresponding to DL subframes.

In an embodiment, the target cell can send at least one of the following configuration/information to the source cell, which is to be observed by the source cell during the DAPS handover, to be considered by the source cell for source cell configuration update or modification, and/or to be considered by the source cell for the new HO preparation:

1. The UE capability information, which is selected/used or requested by the target cell in the DAPS HO. More specifically, the UE capability information includes at least one of the following information:

1) Bandcombination (BC) information, which can be indicated as an index or a list of indices referring to band combinations in the MR-DC, CA, and/or DAPS capabilities.

3) The FeatureSetUplink/Downlink information, which can be indicated as an index or a list of indices (e.g., FeatureSetDownlinkId, FeatureSetUplinkId) referring to the position of the FeatureSetDownlink and/or FeatureSetUplink.

5) The FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC information, which can be indicated as an index or a list of indices (e.g., the parameters FeatureSetDownlinkPerCC-Id and FeatureSetUplinkPerCC-Id) referring to the position of the FeatureSetDownlinkPerCC and/or FeatureSetUplinkPerCC.

2. FR information in target cell group, e.g., the parameter fr-InfoListTarget, which contains FR information (e.g., FR1 or FR2) of serving cells (e.g., PCell, PSCell, SCell (s) ) configured in the target cell group.

3. The power headroom (PH) information in the target cell group that is needed in the reception of PHR MAC CE in source cell group, e.g., the parameter ph-InfoTarget. This information may include a list of serving cell indexes in the target cell group and the power headroom types (e.g., type 1, type 2 or type 3) for the associated serving cells (e.g., the PCell and activated the SCells) , and may also include the power headroom type for the supplementary uplink carrier.

4. The power coordination information, which includes at least one of the following indications:

1) The requested maximum power for the serving cells on FR1 in the target cell group that the UE can use in the target cell group, e.g., the parameter requestedP-MaxFR1-Target.

2) The requested maximum power for the serving cells on FR2 in the target cell group that the UE can use in the target cell group, e.g., the parameter requestedP-MaxFR2-Target.

3) The requested maximum power for the serving cells in the target cell group that the UE can use in the target cell group, e.g., the parameter requestedP-Max-Target.

4) The selected Toffset value the target cell is allowed to use for scheduling target transmissions, e.g., the parameter selectedToffset.

5) The requested new Toffset value the target cell is allowed to use for scheduling target transmissions, e.g., the parameter requestedToffset.

1) The requested maximum number of inter-frequency carriers the target cell is allowed to configure for measurements, e.g., the parameter requestedMaxMeasFreqsTarget.

2) The requested maximum number of allowed measurement identities to configure for inter-frequency measurement, e.g., the parameter requestedMaxInterFreqMeasIdTarget.

3) The requested maximum number of allowed measurement identities to configure for intra-frequency measurement on each serving frequency, e.g., the parameter requestedMaxIntraFreqMeasIdTarget.

6. The requested maximum number of cells that the target node is allowed to configure for PDCCH blind detection, e.g., the parameter requestedPDCCH-BlindDetectionTarget.

7. Resources utilization coordination information, which includes at least one of the following indications:

1) a bit string or bitmap to indicate whether a specific frequency and time resource is intended to be used by the target node. The source node assumes the resource which is not intended to be used by the target can be used for the source cell.

2) an offset value, to indicate the offset of the subframe position or the PRB position in the bitmap or bit string. The source node assumes the original bitmap with the applying of the offset is intended to be used by the source (from the target request) .

Aspect 5-Example 1 (for Aspect 5-Option 1) :

Step 1: The source node requests the DAPS HO to the target node via a Handover Request message, which contains the RRC message HandoverPreparationInformation. The Handover Request message or the RRC message may include restriction/coordination information to be observed by the target cell during the DAPS handover. For example, the information may include at least one of the following indications:

-the UE capability used in the source cell (e.g., BandCombination (s) , band entry/entries, FeatureSetUplink/FeatureSetDownlink (s) , FeatureSetCombination (s) , FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC (s) selected by the source cell) ;

-the UE capability allowed to be used by the target cell (e.g., BandCombination (s) , band entry/entries, FeatureSetUplink/FeatureSetDownlink (s) , FeatureSetCombination (s) , FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC (s) allowed to be selected by the source cell) ;

-the power coordination information (e.g., the maximum total transmit power to be used by the UE in the source/target cell group) ;

-the serving cell number/range that the target node is allowed to configure for the target serving cells;

-the maximum number of cells that the target node is allowed to configure for PDCCH blind detection;

-measurement coordination information (e.g., the maximum number of inter-frequency carriers the target cell is allowed to configure for measurements, the maximum number of allowed measurement identities that the target cell is allowed to configure for inter-frequency measurement and/or for intra-frequency measurement on each serving frequency) ;

-the power headroom (PH) information in the source cell group that is needed in the reception of the PHR MAC CE in the target cell group; or

-the FR information in the source cell group.

Step 2: The target node takes the received restriction/coordination information into account, and generates the target cell configuration matching the UE capability restriction (i.e., the received restriction/coordination information) during the DAPS HO. The target node sends the Handover Request Acknowledge message to the source node including the generated target cell configuration.

Aspect 5-Example 1a (for Aspect 5-Option 1) : Resources utilization coordination

This example is described with reference to FIG. 7.

Step 1: The source node requests the DAPS HO to the target node via the Handover Request message, which may include resources coordination information to indicate whether a specific frequency and time resource is intended to be used by the source node. For example, the information may include at least one of the following indications:

-a bit string or bitmap for UL coordination, to indicate whether a specific frequency and time resource is intended to be used by the source cell on UL transmission;

-a bit string or bitmap for DL coordination, to indicate whether a specific frequency and time resource is intended to be used by the source cell on DL transmission; or

-the reference cell ID for UL and/or DL coordination, e.g., the CGI (Cell Global Identity) of the source PCell.

Step 2: The target node generates the corresponding target cell configuration and sends it to the source node via the Handover Request Acknowledge message. The target node assumes the resource which is not intended to be used by the source cell can be used by the target cell during the DAPS HO and schedules data transmission and/or reception with the UE based on the available resources.

Aspect 5-Example 2 (for Aspect 5-Option 2) :

Step 1: The source node requests a DAPS HO to the target node via the Handover Request message.

Step 2: The target node decides to admit the DAPS HO and sends the generated target cell configuration to the source node via the Handover Request Acknowledge message, which contains the RRC message of HandoverCommand. The Handover Request Acknowledge message or the RRC message may include some restriction/coordination information to be observed by the source cell during the DAPS handover. For example, the information may include at least one of the following indications:

-UE capability used in the target cell (e.g., BandCombination (s) , band entry/entries, FeatureSetUplink/FeatureSetDownlink (s) , FeatureSetCombination (s) , FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC (s) selected by the target cell) ;

-FR information in the target cell group; or

-The power headroom (PH) information in the target cell group that is needed in the reception of the PHR MAC CE in the source cell group.

Step 3: The source node takes the received restriction/coordination information into account, and generates the updated source cell configuration (e.g., releases some source SCell (s) or SCG) and send it to the UE via the RRC Reconfiguration message.

Aspect 5-Example 2a (for Aspect 5-Option 2) : Resources utilization coordination

This example is described with reference to FIG. 8.

Step 2: The target node decides to admit the DAPS HO and sends the generated target cell configuration to the source node via the Handover Request Acknowledge message. The message may include resources coordination information to indicate whether a specific frequency and time resource is intended to be used by the target cell. For example, the information may include at least one of the following indications:

-a bit string or bitmap for UL coordination, to indicate whether a specific frequency and time resource is intended to be used by the target cell on UL transmission;

-a bit string or bitmap for DL coordination, to indicate whether a specific frequency and time resource is intended to be used by the target cell on DL transmission; or

-the reference cell ID for UL and/or DL coordination, e.g., the CGI of the target PCell.

Step 3: The source node assumes the resource which is not intended to be used by the target cell can be used for the source cell during the DAPS HO and schedules the UE based on the available resources.

Aspect 5-Example 3 (for Aspect 5-Option 3) :

Step 1: as in Step 1 in Aspect 5-Example 1.

Steps 2 and 3: as in

Steps

2 and 3 in Aspect 5-Example 2.

Aspect 5-Example 3a (for Aspect 5-Option 3) : Resources utilization coordination

This example is described with reference to FIG. 9.

Step 1: as in Step 1 in Aspect 5-Example 1a.

Step 2: the target node decides to admit the DAPS HO but determines to have or request a new coordination pattern. The target node sends the generated target cell configuration to the source node via the Handover Request Acknowledge message. The message may include the new resources coordination information to indicate whether a specific frequency and time resource is intended to be used by the target cell (as in Step 2 in Aspect 5-Example 2a) . Or the message may include an offset-value indication, to indicate the offset of the subframe position or the PRB position based on the previous pattern, where the previous pattern with the applying of the offset is intended to be used by the source cell.

Step 3: as in Step 3 in Aspect 5-Example 2a.

Aspect 5-Example 4 (for Aspect 5-Option 4) :

Step 1: as in Step 1 in Aspect 5-Example 1.

Step 2: the target node may not meet some restrictions/coordination and/or the target node may determine to request some other resources. The target node rejects the DAPS HO request via sending a Handover Preparation Failure message (or a new message) to the source node, which may include an indication or cause value to indicate the DAPS HO failure and/or may include requested/reference information to be observed by the source cell during the DAPS handover. For example, the information may include at least one of the following indications:

-UE capability requested by the target cell in the DAPS HO (e.g., BandCombination (s) , band entry/entries, FeatureSetUplink/Downlink (s) , FeatureSetCombination (s) , FeatureSetDownlinkPerCC/FeatureSetUplinkPerCC (s) requested by the target cell) ;

-the power coordination information requested by the target cell (e.g., the requested maximum power for the serving cells in the target cell group that the UE can use in the target cell group) ;

-measurement coordination information requested by the target cell (e.g., the requested maximum number of inter-frequency carriers the target cell is allowed to configure for measurements, the requested maximum number of allowed measurement identities to configure for inter-frequency measurement and/or intra-frequency measurement on each serving frequency) ; or

-the requested maximum number of cells that the target node is allowed to configure for PDCCH blind detection.

Step 3: The source node takes the received restriction/coordination information into account, and may generate the updated source cell configuration (e.g., release some source SCell (s) or SCG) . Additionally, the source node may initiate a new handover preparation via sending a new Handover Request to the target node.

Aspect 5-Example 4a (for Aspect 5-Option 4) : Resources utilization coordination

This example is described with reference to FIG. 10.

Step 1: as in Step 1 in Aspect 5-Example 1a.

Step 2: the target node determines to have or request a new coordination pattern and decides to reject the DAPS HO. The target node sends the Handover Preparation Failure message to the source node. The message may include an indication or cause value to indicate the failure is caused by resources coordination failure, and/or the requested resources coordination information to indicate whether a specific frequency and time resource is intended to be used by the target (as in Step 2 in Aspect 5-Example 2a) , or an offset-value indication to indicate the offset of the subframe position or the PRB position based on the previous pattern, where the previous pattern with the applying of the offset is intended to be used by the source cell.

Step 3: the source node takes the received resources coordination information into account, and initiates a new handover preparation procedure to the target node.

Aspect 6: Capability indication

According to some capability mechanisms, the source and target nodes may count the carriers associated with the deactivated/suspended SCell/SCG in the BC when performing the UE capability coordination. However, the UE or the NW does not use the resources on the deactivated/suspended carriers.

In some embodiments of the present disclosure, an indication can be considered to indicate that the deactivated/suspended SCell/SCG is not counted against the total number of carriers the UE can support during capability coordination by the following alternatives:

Alt. 1: the UE sends the indication to the NW via the UE capability report (e.g., include an indicator in the UECapabilityInformation message) .

Alt. 2: the NW sends the indication the UE via dedicated RRC signaling (e.g., include an indicator in the RRC reconfiguration message) or a broadcast message (e.g., include an indicator in the SI message) .

In this manner, the source and target nodes do not consider the carriers associated with the deactivated or suspended SCell/SCG in the BC for UE capability coordination, so that the complexity on UE capability coordination can be significantly reduced. Besides, the UE does not consider such configurations as a mistake.

FIG. 11 relates to a schematic diagram of a wireless communication terminal 30 (e.g., a terminal node or a terminal device) according to an embodiment of the present disclosure. The wireless communication terminal 30 may be a user equipment (UE) , a mobile phone, a laptop, a tablet computer, an electronic book or a portable computer system and is not limited herein. The wireless communication terminal 30 may include a processor 300 such as a microprocessor or Application Specific Integrated Circuit (ASIC) , a storage unit 310 and a communication unit 320. The storage unit 310 may be any data storage device that stores a program code 312, which is accessed and executed by the processor 300. Embodiments of the storage code 312 include but are not limited to a subscriber identity module (SIM) , read-only memory (ROM) , flash memory, random-access memory (RAM) , hard-disk, and optical data storage device. The communication unit 320 may a transceiver and is used to transmit and receive signals (e.g., messages or packets) according to processing results of the processor 300. In an embodiment, the communication unit 320 transmits and receives the signals via at least one antenna 322.

In an embodiment, the storage unit 310 and the program code 312 may be omitted and the processor 300 may include a storage unit with stored program code.

The processor 300 may implement any one of the steps in exemplified embodiments on the wireless communication terminal 30, e.g., by executing the program code 312.

The communication unit 320 may be a transceiver. The communication unit 320 may as an alternative or in addition be combining a transmitting unit and a receiving unit configured to transmit and to receive, respectively, signals to and from a wireless communication node.

In some embodiments, the wireless communication terminal 30 may be used to perform the operations of the UE described above. In some embodiments, the processor 300 and the communication unit 320 collaboratively perform the operations described above. For example, the processor 300 performs operations and transmit or receive signals, message, and/or infroamtion through the communication unit 320.

FIG. 12 relates to a schematic diagram of a wireless communication node 40 (e.g., a network device) according to an embodiment of the present disclosure. The wireless communication node 40 may be a satellite, a base station (BS) , a network entity, a Mobility Management Entity (MME) , Serving Gateway (S-GW) , Packet Data Network (PDN) Gateway (P-GW) , a radio access network (RAN) , a next generation RAN (NG-RAN) , a data network, a core network or a Radio Network Controller (RNC) , and is not limited herein. In addition, the wireless communication node 40 may include (perform) at least one network function such as an access and mobility management function (AMF) , a session management function (SMF) , a location management function (LMF) , a location retrieve function (LRF) , a user place function (UPF) , a policy control function (PCF) , an application function (AF) , etc. The wireless communication node 40 may include a processor 400 such as a microprocessor or ASIC, a storage unit 410 and a communication unit 420. The storage unit 410 may be any data storage device that stores a program code 412, which is accessed and executed by the processor 400. Examples of the storage unit 412 include but are not limited to a SIM, ROM, flash memory, RAM, hard-disk, and optical data storage device. The communication unit 420 may be a transceiver and is used to transmit and receive signals (e.g., messages or packets) according to processing results of the processor 400. In an example, the communication unit 420 transmits and receives the signals via at least one antenna 422.

In an embodiment, the storage unit 410 and the program code 412 may be omitted. The processor 400 may include a storage unit with stored program code.

The processor 400 may implement any steps described in exemplified embodiments on the wireless communication node 40, e.g., via executing the program code 412.

The communication unit 420 may be a transceiver. The communication unit 420 may as an alternative or in addition be combining a transmitting unit and a receiving unit configured to transmit and to receive, respectively, signals, messages, or information to and from a wireless communication terminal.

In some embodiments, the wireless communication node 40 may be used to perform the operations of the source node or the target node described above. In some embodiments, the processor 400 and the communication unit 420 collaboratively perform the operations described above. For example, the processor 400 performs operations and transmit or receive signals through the communication unit 420.

FIG. 13 illustrates a wireless communication method according to an embodiment of the present disclosure. In an embodiment, the wireless communication method may be performed by using a wireless communication terminal (e.g., a UE) .

In an embodiment, the wireless communication method includes operations S11, S12 and S13.

Operation S11 includes receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous-connectivity-based handover. In one embodiment, the first wireless communication node can be the source node described above. The handover command can be the RRC Reconfiguration message described above.

Operation S12 includes performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node. In one embodiment, the first wireless communication node can be the target node described above.

Operation S13 includes maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.

Details in this regard can be ascertained with reference to the paragraphs above, and will not be repeated herein.

FIG. 14 illustrates a wireless communication method according to an embodiment of the present disclosure. In an embodiment, the wireless communication method may be performed by using a wireless communication node (e.g., a network device) . In an embodiment, the wireless communication node may be implemented by using the source node described above, but is not limited thereto.

In an embodiment, the wireless communication method includes operation S21.

Operation S21 includes transmitting, by a first wireless communication node, a handover command to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous-connectivity-based handover from the first wireless communication node to a second wireless communication node.

While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand exemplary features and functions of the present disclosure. Such persons would understand, however, that the present disclosure is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any one of the above-described exemplary embodiments.

It is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any one of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A skilled person would further appreciate that any one of the various illustrative logical blocks, units, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, various forms of program or design code incorporating instructions (which can be referred to herein, for convenience, as "software" or a "software unit” ) , or any combination of these techniques.

To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, units, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure. In accordance with various embodiments, a processor, device, component, circuit, structure, machine, unit, etc. can be configured to perform one or more of the functions described herein. The term “configured to” or “configured for” as used herein with respect to a specified operation or function refers to a processor, device, component, circuit, structure, machine, unit, etc. that is physically constructed, programmed and/or arranged to perform the specified operation or function.

Furthermore, a skilled person would understand that various illustrative logical blocks, units, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, units, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein. If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium.

Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "unit" as used herein, refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various units are described as discrete units; however, as would be apparent to one of ordinary skill in the art, two or more units may be combined to form a single unit that performs the associated functions according embodiments of the present disclosure.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present disclosure. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present disclosure with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the present disclosure. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below.

Claims

A wireless communication method comprising:

receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous-connectivity-based handover; and

performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node; and

maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.
The wireless communication method of claim 1, wherein the handover command comprises at least one of:

a first indication for an activation state of at least one of: a target secondary cell, SCell, or a target secondary cell group, SCG, or

a first triggering condition for an activation of at least one of: a target SCell or a target SCG.
The wireless communication method of claim 1 or 2 further comprising:

receiving, by a wireless communication terminal, from a first wireless communication node, a radio resource control, RRC, message, before reception of the handover command, wherein the RRC message comprises at least one of: a second indication for an activation state of at least one of: a source SCell or a source SCG, or a second triggering condition for an activation of at least one of: a source SCell or a source SCG.
The wireless communication method of any of claims 1 to 3 further comprising, wherein in response to at least one of: a reception of the handover command, or a reception of the first indication for the activation state of at least one of the target SCell or the target SCG, or a reception of the second indication for the activation state of at least one of the source SCell or the source SCG, the wireless communication terminal performs at least one of:

switching, by the wireless communication terminal, the at least one of: the source SCell, the source SCG, the target SCell, or the target SCG, from an activated state to a deactivated state, a dormancy state, or a suspension state; or

configuring, by the wireless communication terminal, the at least one of: the source SCell, the source SCG, the target SCell, or the target SCG, in a deactivated state, a dormancy state, or a suspension state.
The wireless communication method of any of claims 1 to 4 further comprising:

activating or resuming, by the wireless communication terminal, at least one of the target SCell or the target SCG in response to the handover procedure being completed, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormancy state or a suspended state during the handover procedure.
The wireless communication method of any of claims 1 to 4 further comprising:

activating or resuming, by the wireless communication terminal, at least one of the target SCell or the target SCG in response to a random access to a target primary cell, PCell, being successfully completed, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormancy state or a suspended state during the handover procedure before the random access to the target PCell is completed successfully.
The wireless communication method of claim 5 or 6, wherein the at least one of the target SCell or the target SCG is activated in response to the first triggering condition for the corresponding target SCell or the target SCG in the handover command being satisfied.
The wireless communication method of claim 7, wherein the wireless communication terminal starts evaluating the at least one first triggering condition for at least one of the target SCell or the target SCG, in response to at least one of: a reception of the handover command, a completion of a successful random access to a target PCell, or a successful completion of the handover procedure.
The wireless communication method of any of claims 1 to 4 further comprising:

activating or resuming, by the wireless communication terminal, at least one of the source SCell or the source SCG in response to the wireless communication terminal falling back to a source cell upon detection of a handover failure.
The wireless communication method of claim 9, wherein the at least one of the source SCell or the source SCG is activated in response to the second triggering condition for the corresponding source SCell or source SCG being satisfied.
The wireless communication method of claim 10, wherein the wireless communication terminal starts evaluating the at least one second triggering condition for at least one of the source SCell or the source SCG, in response to at least one of: a reception of the RRC message, or upon the wireless communication terminal falling back to the source cell.
The wireless communication method of claim 1, wherein in response to a failure of the source SCell or the source SCG being detected during the handover procedure, the wireless communication terminal performs at least one of:

suspending transmission and reception of all data radio bearers in the source SCell or the source SCG;

resetting a media access control, MAC, for the source SCG;

releasing a connection of the source SCell or the source SCG; or

releasing a configuration of the source SCell or the source SCG.
The wireless communication method of claim 1 further comprising:

deactivating or suspending, by the wireless communication terminal, the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.
The wireless communication method of claim 1 further comprising:

detaching, by the wireless communication terminal, from a source cell in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.
The wireless communication method of claim 1 further comprising:

transmitting, by the wireless communication terminal, an indication to a network node indicating that a total number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a calculation of a capability of the wireless communication terminal during a capability coordination procedure,

wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.
The wireless communication method of claim 1 further comprising:

receiving, by the wireless communication terminal, an indication from a network node indicating that a total number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a calculation of a capability of the wireless communication terminal during a capability coordination,

wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.
A wireless communication method comprising:

transmitting, by a first wireless communication node, a handover command to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous-connectivity-based handover from the first wireless communication node to a second wireless communication node.
The wireless communication method of claim 17, wherein the handover command comprises at least one of: a first indication for an activation state of at least one of: a target secondary cell, SCell, or a target secondary cell group, SCG, or a first triggering condition for an activation of at least one of: a target SCell, or a target SCG.
The wireless communication method of claim 17 further comprising:

transmitting, by the first wireless communication node, a radio resource control, RRC, message, before reception of the handover command, wherein the RRC message comprises at least one of: a second indication for an activation state of at least one of: a source SCell or a source SCG, or a second triggering condition for an activation of at least one of: a source SCell or a source SCG.
The wireless communication method of claim 17 further comprising:

transmitting, by the first wireless communication node, an indication to the wireless communication terminal to instruct the wireless communication terminal deactivating or suspending the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.
The wireless communication method of claim 17 further comprising:

transmitting, by the first wireless communication node, an indication to the wireless communication terminal to instruct the wireless communication terminal detaching from a source cell in response to a number of cells configured to the wireless communication terminal exceeding a capability of the wireless communication terminal.
The wireless communication method of claim 17 further comprising:

receiving, by the first wireless communication node, an indication from the wireless communication terminal indicating that a number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a total number of configured carriers of the wireless communication terminal during a capability coordination procedure,

wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.
The wireless communication method of claim 17 further comprising:

transmitting, by the first wireless communication node, an indication to the wireless communication terminal indicating that a number of carriers of the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are not counted in a total number of configured carriers of the wireless communication terminal during a capability coordination procedure,

wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG are deactivated or suspended in the handover procedure.
A wireless communication terminal, comprising:

a communication unit; and

a processor configured for:

receiving, by a wireless communication terminal, from a first wireless communication node, a handover command indicating use of a simultaneous connectivity based handover; and

performing, by the wireless communication terminal, a handover procedure from the first wireless communication node to a second wireless communication node ; and

maintaining, by the wireless communication terminal, the connection with the first wireless communication node until completion of the handover procedure.
The wireless communication terminal of claim 24, wherein the processor is further configured to perform a wireless communication method of any of claims 2 to 16.
A wireless communication node, comprising:

a communication unit; and

a processor configured for:

transmitting, by a first wireless communication node, a handover command to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous connectivity based handover from the first wireless communication node to a second wireless communication node.
The wireless communication node of claim 26, wherein the processor is further configured to perform a wireless communication method of any of claims 18 to 23.
A computer program product comprising a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a wireless communication method recited in any of claims 1 to 23.