CN116897559A

CN116897559A - Methods, apparatus and computer program products for wireless communication

Info

Publication number: CN116897559A
Application number: CN202180094213.3A
Authority: CN
Inventors: 张梦洁; 黄河; 刘静
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2023-10-17
Also published as: EP4256849A4; WO2022227046A1; EP4256849A1

Abstract

The present disclosure provides methods, apparatus, and computer program products for wireless communication. A method comprising: the wireless communication terminal receiving a handover command from the first wireless communication node indicating to use a handover based on the simultaneous connection; and the wireless communication terminal performing a handover procedure from the first wireless communication node to a second wireless communication node; and the wireless communication terminal maintaining a connection with the first wireless communication node until the handover procedure is completed.

Description

Methods, apparatus and computer program products for wireless communication

Technical Field

The present disclosure relates generally to wireless communications.

Background

A simultaneous connection based handover procedure may be used to reduce mobility disruption. During the handover procedure, a User Equipment (UE) maintains simultaneous connection with the source cell and the target cell until the handover procedure is completed, e.g., the source cell is released after successful random access to the target cell. Dual Active Protocol Stack (DAPS) Handoff (HO) is one example of this type of handoff. The handover based on simultaneous connection is denoted as DAPS HO in the following.

However, during DAPS HO, only the source and target primary cells (PCell) can be maintained. Before sending the HO command to the UE, the source cell releases the source secondary cell (SCell) and/or the source Secondary Cell Group (SCG) (also denoted source SCell/SCG in the following). Furthermore, the target cell cannot configure the target SCell and/or the target SCG (also denoted as target SCell/SCG hereinafter) in the HO command. The release of SCell/SCG may significantly reduce throughput on the source link, which may impair the user experience of the UE.

DAPS HO in the case of FR2 (frequency range 2 (i.e., 24.25-52.6 GHz)) to FR2 is not supported in some methods because simultaneous reception and transmission of HO from FR2 to FR2 is difficult to support based on UE capability. However, it is still desirable in FR2 to reduce HO interruption time, especially in view of smaller cells at high frequencies and frequent HO.

Disclosure of Invention

In view of the foregoing, mobility enhancement methods are provided in various embodiments of the present disclosure for improving mobility performance (including improving reliability and/or reducing outage time) for Dual Connectivity (DC), carrier Aggregation (CA), and/or FR2 scenarios.

The present disclosure relates to methods, apparatus and computer program products for wireless communication that may improve reliability during handoff.

One aspect of the present disclosure relates to a wireless communication method. In one embodiment, the wireless communication method includes: receiving, by the wireless communication terminal, a handover command from the first wireless communication node indicating to use a handover based on the simultaneous connection; 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, a connection with the first wireless communication node until the handover procedure is completed.

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

Another aspect of the present disclosure relates to a wireless communication terminal. In one embodiment, the wireless communication terminal includes a communication unit and a processor. The processor is configured to: receiving, by the wireless communication terminal, a handover command from the first wireless communication node indicating to use a handover based on the simultaneous connection; 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, a connection with the first wireless communication node until the handover procedure is completed.

Another aspect of the present disclosure relates to a wireless communication node. In one embodiment, the wireless communication node includes a communication unit and a processor. The processor is configured to transmit a handover command by a first wireless communication node to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous connection-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 of an activation state for at least one of a target secondary cell (SCell) or a target Secondary Cell Group (SCG); or a first trigger condition for activation of at least one of the target SCell or the target SCG.

Preferably, the method further comprises receiving, by the wireless communication terminal, a Radio Resource Control (RRC) message from the first wireless communication node prior to receiving the handover command, wherein the RRC message comprises at least one of: a second indication of an activation state for at least one of the source SCell or the source SCG; or a second trigger condition for activation of at least one of the source SCell or the source SCG.

Preferably, the method further comprises, in response to at least one of: the wireless communication terminal performs at least one of the following upon receiving the handover command, upon receiving the first indication of the activation state for at least one of the target SCell or the target SCG, or upon receiving the second indication of the activation state for at least one of the source SCell or the source SCG: the wireless communication terminal transitions the at least one of the source SCell, the source SCG, the target SCell, or the target SCG from an active state to a deactivated state, a dormant state, or a suspended state; or the wireless communication terminal configures the at least one of the source SCell, the source SCG, the target SCell, or the target SCG to a deactivated state, a dormant state, or a suspended state.

The wireless communication terminal transitions the at least one of the source SCell, the source SCG, the target SCell, or the target SCG from an active state to a deactivated state, a dormant state, or a suspended state in response to at least one of: the handover command is received, or a first indication of an activation state for at least one of the target SCell or the target SCG is received, or a second indication of an activation state for at least one of the source SCell or the source SCG is received.

Preferably, the method further comprises: the wireless communication terminal activates at least one of the target SCell or the target SCG in response to completion of the handover procedure, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormant state, or a suspended state during the handover procedure.

Preferably, the method further comprises: in response to successful completion of random access to a target primary cell (PCell), the wireless communication terminal activates at least one of the target SCell or the target SCG, wherein the at least one of the target SCell or the target SCG is in a deactivated state, a dormant state, or a suspended state during the handoff before the random access to the target PCell is successfully completed.

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

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

Preferably, the method further comprises: in response to the wireless communication terminal fallback to the source cell upon detection of a handover failure, the wireless communication terminal activates at least one of the source SCell or the source SCG.

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

Preferably, the wireless communication terminal starts to evaluate at least one second trigger condition for at least one of the source SCell or the source SCG in response to at least one of receiving the RRC message or when the wireless communication terminal falls back to the source cell.

Preferably, in response to detecting a failure of the source SCell or the source SCG 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 Medium Access Control (MAC) for the source SCG; releasing the connection of the source SCell or the source SCG; or release the configuration of the source SCell or the source SCG.

Preferably, the method further comprises: the wireless communication terminal deactivates or suspends the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to the number of cells configured to the wireless communication terminal exceeding the capability of the wireless communication terminal.

Preferably, the method further comprises: the wireless communication terminal leaves the source cell in response to the number of cells configured to the wireless communication terminal exceeding the capability of the wireless communication terminal.

Preferably, the method further comprises: the wireless communication terminal sends 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 is not counted in a capability calculation 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 is deactivated or suspended during the handover procedure.

Preferably, the method further comprises: the wireless communication terminal receives 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 during a capability coordination procedure is not counted in a capability calculation of the wireless communication terminal, wherein the at least one of the source SCell, the source SCG, the target SCell, or the target SCG is deactivated or suspended during the handover procedure.

Preferably, the method further comprises: before receiving the handover command, the first wireless communication node transmits a Radio Resource Control (RRC) message, wherein the RRC message includes at least one of: a second indication of an activation state for at least one of the source SCell or the source SCG; or a second trigger condition for activation of at least one of the source SCell or the source SCG.

Preferably, the method further comprises: an indication is sent by the first wireless communication node to the wireless communication terminal to instruct the wireless communication terminal to deactivate or suspend the at least one of the source SCell, the source SCG, the target SCell, or the target SCG in response to the number of cells configured to the wireless communication terminal exceeding the capability of the wireless communication terminal.

Preferably, the method further comprises: the first wireless communication node sends an indication to the wireless communication terminal to instruct the wireless communication terminal to leave a source cell in response to the number of cells configured to the wireless communication terminal exceeding the capabilities of the wireless communication terminal.

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

The exemplary embodiments disclosed herein are intended to provide features that will become apparent by reference to the following description in conjunction with the accompanying drawings. According to various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. However, it should be understood that these embodiments are presented by way of example and not limitation, and that various modifications of the disclosed embodiments may be made while remaining within the scope of the disclosure, as will be apparent to those of ordinary skill in the art from reading the disclosure.

Thus, the disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the particular order and/or hierarchy of steps in the methods disclosed herein is merely exemplary. Based on design preferences, the specific order or hierarchy of steps in the disclosed methods or processes may be rearranged while remaining within the scope of the present disclosure. Accordingly, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in an example order, and that the present disclosure is not limited to the particular order or hierarchy presented, unless specifically stated otherwise.

Drawings

The above and other aspects and implementations thereof are described in more detail in the accompanying drawings, description and claims.

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

Fig. 2 shows a flow chart of a wireless communication method according to an embodiment of the present disclosure.

Fig. 3 shows a flow chart of a wireless communication method according to another embodiment of the present disclosure.

Fig. 4a and 4b illustrate a flow chart of a wireless communication method according to another embodiment of the present disclosure.

Fig. 5a and 5b illustrate a flow chart of a wireless communication method according to another embodiment of the present disclosure.

Fig. 6 illustrates a bit string or bitmap according to an embodiment of the present disclosure.

Fig. 7 shows a schematic diagram of an inter-node coordination process according to an embodiment of the present disclosure.

Fig. 8 shows a schematic diagram of an inter-node coordination process according to another embodiment of the present disclosure.

Fig. 9 shows a schematic diagram of an inter-node coordination process according to another embodiment of the present disclosure.

Fig. 10 shows a schematic diagram of an inter-node coordination process 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 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.

Detailed Description

To reduce mobility disruption, a Dual Active Protocol Stack (DAPS) based handoff procedure may be used. During the DAPS-based handover, the UE maintains simultaneous connection with the source cell and the target cell, and does not release the source cell until after successful random access to the target cell.

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

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

In step 3, the source node sends a Handover Request (Handover Request) message to the target node of the target cell, the Handover Request message including a DAPS indicator indicating that a DAPS HO is requested. In one 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 a handoff request acknowledgement (Handover Request Acknowledge) to the source node, which includes a DAPS response indicator indicating whether the DAPS HO was accepted.

In step 6, the source node triggers a Uu handover by sending an rrcrecon configuration message to the UE. For a Data Radio Bearer (DRB) configured with a DAPS, the source node does not stop sending downlink data packets until a Handover Success message is received from the target node in step 9 a.

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

In steps 8 and 9, the UE initiates random access to the target cell and completes the RRC handover procedure by transmitting an rrcrecconfiguration complete message to the target node. In the case of DAPS HO, the UE does not leave the source cell when receiving the rrcrecon configuration message. In contrast, in step 9c, the UE releases the source connection and configuration upon receiving an explicit release from the target node.

In steps 9a and 9b, in case of a DAPS HO, the target node sends a handover success message to the source node informing the UE that the target cell has been successfully accessed. In return, the source node sends SN Status Transfer a message for the DRB configured with the DAPS.

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

Aspect 1: processing of SCell/SCG during DAPS HO

If one or more source and/or target scells/SCGs (also denoted source/target scells/SCGs hereinafter) are allowed to be used during a DAPS HO, several options for source/target SCell/SCG handling may be considered:

option 1: the source SCell/SCG and/or the target SCell/SCG is allowed to remain/configure in any state, e.g. active/deactivated/dormant/suspended.

Option 2: the source SCell/SCG and/or the target SCell/SCG are not allowed to remain/configure in an active state, i.e. can only be in a deactivated/dormant/suspended state.

Option 3: the source SCell/SCG is released or removed and the target SCell/SCG is allowed to remain or be configured in any state, e.g. active/deactivated/dormant/suspended state.

Option 4: the source SCell/SCG may be released or removed and the target SCell/SCG is not allowed to remain or be configured in an active state, i.e. can only be in a deactivated/dormant/suspended state.

If the source and/or target scells/SCGs are not allowed to be in an active state during DAPS HO, several alternatives may be considered to change or configure the UE's source and/or target scells/SCG states:

Alternative 1: a Network (NW) (e.g., a network node such as a source node or a target node) explicitly configures/transitions SCell/SCG status to a deactivated/dormant/suspended state by, for example, including an indication in an RRC message (e.g., an RRC reconfiguration message) to indicate SCell/SCG status as a deactivated/dormant/suspended state, transmitting a MAC CE (medium access control element) or DCI (data control information) to transition an activated SCell/SCG to a deactivated/dormant/suspended state.

Alternative 2: upon receiving the DAPS HO command, the UE implicitly switches the source/target SCell/SCG state from active to inactive/dormant/suspended.

In case the source/target SCell/SCG is in the above-described deactivated/dormant/suspended state, the UE may perform at least one of the following:

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

2. stopping monitoring a Physical Downlink Control Channel (PDCCH) on the source/target SCell/PSCell;

3. stopping Channel State Information (CSI) reporting; or alternatively

4. Switch to dormant bandwidth portion (BWP) on source/target SCell/PSCell.

In some embodiments, for suspension of the source SCG, the source cell (e.g., source node of the source cell) may first reconfigure all SCG bearers terminating at the SN or separate bearers terminating at the SN to MCG bearers terminating at the SN or MCG bearers terminating at the MN. Subsequently, the source cell may release the SCG configuration to the UE via an RRC message (e.g., an RRC reconfiguration message). In this case, the UE may maintain an SN SDAP (service data adaptation protocol)/PDCP (packet data convergence protocol) configuration and SN key and release 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., target node of the target cell) may configure or indicate the target SCell/SCG as active/inactive/dormant/suspended state in a HO command (i.e., RRC reconfiguration message) to the UE.

Aspect 1-example 2a (for aspect 1-option 2):

in an embodiment, prior to (or concurrent with) sending the HO command (i.e., RRC reconfiguration message) to the UE, the source cell deactivates or suspends the source SCell/SCG via RRC signaling (e.g., including an indication in the RRC reconfiguration message to indicate the source SCell/SCG status as deactivated/suspended/dormant) or MAC CE or DCI.

In an embodiment, the target cell deactivates or suspends the target SCell/SCG via the HO command (e.g., including an indication in the RRC reconfiguration message to indicate the target SCell/SCG status as deactivated/suspended/dormant).

Aspect 1-example 2b (for aspect 1-option 2):

in an embodiment, upon receipt of the HO command, the UE automatically deactivates or suspends the source/target SCell/SCG (if any), e.g., the UE stops or suspends 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 an RRC reconfiguration message.

In an embodiment, the target cell configures/indicates the target SCell/SCG as active/deactivated/dormant/suspended state in a HO command (i.e., RRC reconfiguration message) to the UE.

Aspect 1-example 4a (for aspect 1-option 4):

Aspect 1-example 4b (for aspect 1-option 4):

Aspect 2: fast activation or recovery of SCell/SCG

In an embodiment, if the SCell/SCG is in a deactivated/suspended/dormant state during a DAPS HO, the NW or UE may quickly activate or resume the SCell/SCG when the UE rolls back to the source cell upon completion of the DAPS HO or in case of HO failure.

There are several options to consider for activation or restoration of the target SCell/SCG.

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

Option 2: after 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 one or more trigger conditions for SCell/SCG activation or recovery in the HO command. When the trigger condition is met or met and the DAPS HO is complete (or after completion), the UE activates or resumes the target SCell/SCG.

Option 4: the target cell configures one or more trigger conditions for SCell/SCG activation or recovery in the HO command. When the trigger condition is met or met and RA to the target PCell completes successfully (or after completion), the UE activates or resumes the target SCell/SCG.

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

Option 6: a 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 the UE automatically activates or resumes the target SCell/SCG when the DAPS HO is complete and uplink data arrives on the target SCG bearer or target SCell/SCG link. The remainder can be deduced by analogy.

There are several alternatives regarding the time at which the UE starts to evaluate one or more trigger or activation conditions of the target SCell/SCG:

alternative 1: upon receiving the HO command (i.e., RRC reconfiguration message) including one or more trigger or activation conditions, the UE starts to evaluate the one or more trigger or activation conditions of the target SCell/SCG.

Alternative 2: the UE starts evaluating one or more trigger or activation conditions of the target SCell/SCG upon completion of the DAPS HO (e.g., upon release of the source cell)

Alternative 3: when RA to the target PCell is successfully completed (e.g., when an indication of successful completion of random access to the target cell is received from a lower layer), the UE begins to evaluate one or more trigger or activation conditions of the target SCell/SCG.

For activation or restoration of the source SCell/SCG, several options may be considered.

Option 1: upon fallback to the source cell, the UE automatically activates or resumes the source SCell/SCG, e.g., when the UE detects a HO failure (e.g., timer T304 expires) and no radio link failure is detected in the source PCell.

Option 2: prior to (or simultaneously with) sending the HO command to the UE, the source cell configures one or more trigger conditions for SCell/SCG activation or recovery in an RRC reconfiguration message. When the trigger condition is met or met and the UE is retracted to the source cell (or after the UE is retracted to the source cell), the UE activates or resumes the source SCell/SCG.

Option 3: the UE automatically activates or resumes the source SCell/SCG while the Time Alignment (TA) timer associated with the source PSCell/SCell is back-off to the source cell and still running.

Option 4: combinations of options 2 and 3. This means that the UE automatically activates or resumes the source SCell/SCG when the UE is back-off to the source cell and the trigger condition is met or met and the Time Alignment (TA) timer associated with the source PSCell/SCG is still running.

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

Option 6: a 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 the UE automatically activates or resumes the source SCell/SCG once the fallback to the source cell and the uplink data arrives on the source SCG bearer or source SCell/SCG link. The remainder can be deduced by analogy.

There are several alternatives regarding the time at which the UE starts to evaluate one or more trigger or activation conditions of the source SCell/SCG:

alternative 1: upon receiving an RRC message (e.g., an RRC reconfiguration message) including one or more trigger or activation conditions for the source cell, the UE begins to evaluate the one or more trigger or activation conditions for the source SCell/SCG.

Alternative 2: upon fallback to the source (i.e., detection of HO failure), the UE starts evaluating one or more trigger or activation conditions of the source SCell/SCG.

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

alternative 1: the UE initiates Random Access (RA) to the source/target PSCell/SCell.

Alternative 2, if a Time Alignment (TA) timer associated with the source/target PSCell/SCell is running, the UE directly resumes UL and/or DL transmission and/or reception with the source/target PSCell/SCell, e.g., transmits UL data to the source/target PSCell/SCell.

In some embodiments, one or more trigger or activation conditions may be considered that configure several alternatives as SCell/SCG activation or restoration:

alternative 1: RSRP (reference signal received power), RSRQ (reference signal received quality) and/or SINR (signal to interference plus noise ratio) thresholds for each cell (e.g., PCI (physical cell ID) and frequency, cell index) or per frequency configuration;

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

alternative 3: measuring events (e.g., events A3, A5, A4, and/or B1, or other events below);

Alternative 4: a threshold for UL data amount, e.g. a threshold for UL data amount for SCG bearers or separate bearers.

The definition of each measurement event is as follows:

event A1 (serving cell becomes better than threshold);

event A2 (serving cell becomes worse than threshold);

event A3 (neighbor cell becomes better than SpCell plus offset (e.g., neighbor cell's radio link quality becomes better than SpCell's radio link quality plus offset));

event A4 (neighbor cell becomes better than threshold);

event A5 (SpCell becomes worse than threshold 1 and neighbor cell becomes better than threshold 2);

event A6 (neighbor cell becomes better than SCell plus offset (e.g., neighbor cell's radio link quality becomes better than SCell's radio link quality plus offset));

event B1 (inter-RAT (radio access technology) neighbor cell becomes better than the threshold); and

event B2 (PCell becomes worse than threshold 1 and inter-RAT neighbor cell becomes better than threshold 2).

In some embodiments, one or more trigger or activation conditions of the target SCell/SCG may be set or configured by the target MN or/and the target SN. In some embodiments, one or more trigger or activation conditions of the source SCell/SCG may be set or configured by the source MN or/and the source SN.

Aspect 2-example 1 (for aspect 2-option 1)

An illustrative example is described below with reference to fig. 2.

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

In an embodiment, the source/target SCell/SCG is in a deactivated/suspended/dormant state (if any). In an embodiment, the operation of configuring or transitioning the SCell/SCG from the active state to the deactivated/suspended/dormant state may be identical or identical to the embodiment in aspect 1.

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

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

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

S204: in case the UE fails to perform RA on the target cell (i.e., timer T304 expires), the UE decides whether to fall back to the source cell. If no RLF (radio link failure) is detected in the source PCell, the UE backs off to the source cell and automatically activates or resumes source SCell/SCG, e.g., initiates RA to the source PSCell/SCell or resumes UL and/or DL transmission and/or reception with the source PSCell/SCell.

In some embodiments, if a Time Alignment (TA) timer associated with the source PSCell/SCell is still running, the UE backs off to the source cell and the UE activates or resumes the source SCell/SCG.

In some embodiments, the UE rolls back to the source cell and activates or resumes the source SCell/SCG when uplink data arrives on the source SCG bearer or source SCell/SCG link.

In some embodiments, the UE backs off to the source cell and activates or resumes the source SCell/SCG when uplink data arrives on the source SCG bearer or source SCell/SCG link and a Time Alignment (TA) timer associated with the source PSCell/SCell is still running.

Aspect 2-example 1 (for aspect 2-option 2)

An illustrative example is described below with reference to fig. 3.

S301 and S302: s201 and S202 as in aspect 2-example 1.

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

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

S304: as described in S204, aspect 2-example 1.

Aspect 2-example 3 (for aspect 2-option 3)

An illustrative example is described below with reference to fig. 4a and 4 b.

S401: the UE receives a HO command (i.e., RRC reconfiguration message) or an RRC reconfiguration message for the source cell from the source node. The HO command may include an indication of the target SCell/SCG status (e.g., SCG status is indicated as deactivated), and/or a trigger condition for activation or restoration of the target SCell/SCG. The RRC reconfiguration message for the source cell may include an indication for the source SCell/SCG status (e.g., SCG status is indicated as deactivated), and/or a trigger condition for the source SCell/SCG activation or recovery.

S402: the UE starts to evaluate the trigger or activation conditions of the target/source SCell/SCG.

S403: the UE maintains a connection with the source cell and performs RA to the target cell and determines whether the UE successfully completes RA to the target cell.

S404: in case the UE successfully completes RA to the target cell, the UE automatically activates or resumes the corresponding target SCell/SCG when the UE receives an indication to release the source cell from the target cell and satisfies a trigger or activation condition of the target SCell/SCG, or when the UE satisfies a trigger or activation condition of the target SCell/SCG after receiving an indication to release the source cell from the target cell, for example, starts RA to the target PSCell/SCel or resumes UL and/or DL transmission and/or reception with the target PSCell/SCG.

In some embodiments, when uplink data arrives at the target SCG bearer or target SCell/SCG link and the trigger or activation condition of the target SCell/SCG is met, and upon (or after) receiving the source release indication, the UE activates or resumes the target SCell/SCG.

S405: in case the UE fails to perform RA on the target cell (i.e., timer T304 expires), the UE decides whether to fall back to the source cell. If no RLF is detected in the source PCell, the UE rolls back to the source cell. When the UE falls back to the source cell and satisfies the trigger or activation condition of the source SCell/SCG, or when the trigger or activation condition of the source SCell/SCG is satisfied after the UE falls back to the source cell, the UE automatically activates or resumes the source SCell/SCG, e.g., initiates RA to the source PSCell/SCell or resumes UL and/or DL transmission and/or reception with the source PSCell/SCell.

In some embodiments, the UE backs off to the source cell and activates or resumes the source SCell/SCG if a Time Alignment (TA) timer associated with the source PSCell/SCG is still running and a trigger or activation condition of the source SCell/SCG is met.

In some embodiments, the UE rolls back to the source cell, and activates or resumes the source SCell/SCG when uplink data arrives on the source SCG bearer or source SCell/SCG link and the trigger or activation condition of the source SCell/SCG is met.

In some embodiments, the UE rolls back to the source cell and activates or resumes the source SCell/SCG when uplink data arrives on the source SCG bearer or source SCell/SCG link and a Time Alignment (TA) timer associated with the source PSCell/scll is still running and trigger or activation conditions of the source SCell/SCG are met.

Note that in some embodiments, the UE starts to evaluate the activation/trigger condition of the target SCell/SCG only after RA of the target cell is successfully completed (i.e., operation S402 is performed after operation S403) or after an indication for releasing the source cell is received from the target cell (i.e., operation S402 is performed within operation S404). In some embodiments, the UE starts to evaluate the activation/trigger condition of the source SCell/SCG only after fallback to the source cell (i.e., performs operation S402 in operation S405).

Aspect 2-example 4 (for aspect 2-option 4)

An illustrative example is described below with reference to fig. 5a and 5 b.

S501-S503: s401 to S403 as in aspect 2 to example 3.

S504: in case the UE successfully completes RA to the target cell, upon satisfaction of trigger or activation conditions of the target SCell/SCG, the UE automatically activates or resumes the corresponding target SCell/SCG, e.g. starts RA to the target PSCell/SCel or resumes UL and/or DL transmission and/or reception with the target PSCell/SCell.

In some embodiments, when uplink data arrives at the target SCG bearer or target SCell/SCG link and the trigger or activation condition of the target SCell/SCG is met, and RA to the target cell is completed (or after RA to the target cell is completed), the UE activates or resumes the target SCell/SCG.

S505: s405 as in aspect 2-example 3.

Note that in some embodiments, the UE starts to evaluate the activation/trigger condition of the target SCell/SCG only after successful completion of RA to the target cell (i.e., performs operation S502 after operation S503). In some embodiments, the UE starts to evaluate the activation/trigger condition of the source SCell/SCG only after fallback to the source cell (i.e., performs operation S502 in operation S505).

Note that in some embodiments, only the source cell configures the trigger or activation conditions for SCell/SCG, or only the target cell configures the trigger or activation conditions for SCell/SCG, and the UE behavior may be any combination of the above examples.

Aspect 3: handling SCell/SCG failure during DASP HO

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

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

resetting the MAC of the source SCG;

releasing the source SCell/SCG connection; or alternatively

The source SCell/SCG configuration is released.

In the case of configuring or maintaining target SCell/SCG, if any target SCell/SCG failure (e.g., RLF or RLC failure) is detected on the target link during DAPS HO, two options may 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 of the target SCG;

releasing the target SCell/SCG connection; or alternatively

The target SCell/SCG configuration is released.

Option 2: an SCell/SCG failure handling method is performed (e.g., a failure information procedure is initiated to report RLC failure, or an SCG failure information procedure is initiated to report SCG RLF).

In some embodiments, RLC failure on SCell may be detected when:

in an indication from the MCG (primary cell group) RLC that the maximum number of retransmissions has been reached and that CA (carrier aggregation) replication is configured and activated for the MCG, and corresponding logical channels allowedServingCells comprising only one or more scells.

In some embodiments, RLF on SCG may be detected when:

when the timer T310 on PSCell expires;

when the timer T312 on PSCell expires;

when there is a random access problem indication from the SCG MAC;

when there is an 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, a BH (backhaul) RLF indication is received from the SCG on a BAP (backhaul adaptation protocol) entity.

Aspect 4: operation beyond UE capability

In some approaches, if SCell/SCG is activated during DAPS HO, the UE will maintain DL/UL reception/transmission with all serving cells on the source and target links. In case the sum of the source cell configuration and/or scheduling and the target cell configuration and/or scheduling exceeds the maximum UE capability, the UE may declare HO failure and trigger RRC re-establishment, which may lead to long interruption times. For this case, some optimizations may be considered:

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

Option 2: the UE rolls back to the regular HO, i.e. the UE leaves the source cell and synchronizes to the target cell.

NW (e.g., a network node such as a source node or a target node) may send an indication to the UE via dedicated RRC signaling (e.g., RRC reconfiguration message) or broadcast signaling (e.g., system information message) to indicate whether or not to allow the above-described optimization (i.e., option 1 or 2).

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

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

Aspect 5: inter-node coordination

Considering that the UE may maintain connectivity with all serving cells on the source and target links during a DAPS HO, coordination/interaction between nodes may be required during the HO preparation phase to ensure that the source and target cell configurations do not exceed the maximum UE capability. For coordination/interaction between nodes, the following options may be considered:

option 1: the source cell indicates or transmits restriction/suggestion/reference/coordination information to the target cell via the HO request message, wherein the target cell observes the restriction/suggestion/reference/coordination information during DAPS handoff.

Option 2: the target cell indicates or transmits the selected/used/requested information to the source cell via a HO request acknowledgement message, wherein the source cell observes the selected/used/requested information during DAPS handoff.

Option 3: both option 1 and option 2 are employed.

Option 4: the source cell indicates/transmits restriction/suggestion/reference/coordination information to the target cell through the HO request message. If the target cell determines to request or use another configuration, the target cell indicates or sends the requested configuration to the source cell via an Xn/X2 message (e.g., a handover preparation failure message). The source cell then considers the requested configuration and decides to update the source configuration and/or initiate a new HO preparation procedure towards the target cell accordingly.

In an embodiment, the constraint/suggestion/reference/coordination information may be sent to the target node by one of the following alternatives:

alternative 1: such information is directly included in the Xn/X2 message, for example as an information element in a handover request message.

Alternative 2: such information is included in an RRC message such as a handover preparation information message. The RRC message is included as one information element in an Xn/X2 message (e.g., handover request message).

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

alternative 1: such information is directly included in the Xn/X2 message, for example as one information element in a handover request acknowledge message or a handover preparation failure message.

Alternative 2: such information is included in an RRC message, such as a handover command message. The RRC message is included as one information element in an Xn/X2 message (e.g., a handover request confirm message).

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

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

1) Band Combination (BC) information, which may be indicated as an index or index list pointing to band combinations in MR-DC (multi-radio dual connectivity), CA and/or DAPS capabilities;

2) One or more band entries in the associated BC, which may be indicated as an index or list of indices pointing to the locations of the band entries.

3) FeaturetUpLink/FeaturetDownlink information, which may be indicated as an index or list of indices (e.g., featureSetDownlinkId, featureSetUplinkId) pointing to the location of FeaturetDownlink and/or FeaturetUpLink.

4) FeaturesCombination information, which may be indicated as an index or list of indices pointing to locations in FeaturesCombination, corresponds to one FeaturesUpLink or FeaturesEtDown Link of each band entry in the associated band combination.

5) FeaturesetDown/FeaturesUpLinkPerCC information, which may be indicated as an index or index list (e.g., featuresetDown PerCC-Id, featuresUpLinkPerCC-Id) pointing to the location of FeaturesetDown PerCC and/or FeaturesUpLinkPerCC.

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

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

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

3) During DAPS handoff, the UE will use the maximum total transmit power in the source MCG/SCG, e.g., parameters p-DAPS-source-MCG and/or p-DAPS-source-SCG.

4) During DAPS handoff, the maximum total transmit power used by the UE in the target MCG/SCG, e.g., parameters p-DAPS-target-MCG and/or p-DAPS-target-SCG.

5) During DAPS handoff, in all serving cells in frequency range 1 (FR 1), the maximum total transmit power used by UEs in the NR (New radio) cell group, e.g., the parameter p-maxNR-FR1.

6) During DAPS handoff, the maximum total transmit power (including MCG and SCG, if configured) used by UEs in the NR cell group in all serving cells in FR1, e.g., the parameter p-maxNR-FR1-source.

7) During DAPS handoff, the maximum total transmit power used by a UE in the NR cell group in all serving cells in FR1, which can be used by the UE in the target cell group (including MCG and SCG if configured), e.g., the parameter p-maxNR-FR1-target.

8) During DAPS handoff, the maximum total transmit power used by the UEs in the NR cell group in all the serving cells in frequency range 2 (FR 2), e.g., the parameter p-maxNR-FR2.

9) During DAPS handoff, the maximum total transmit power (including MCG and SCG, if configured) used by UEs in the NR cell group in all serving cells in FR2, e.g., the parameter p-maxNR-FR2-source.

10 During DAPS handoff, the maximum total transmit power used by a UE in the NR cell group in all serving cells in FR2, which can be used by the UE in the target cell group (including MCG and SCG, if configured), e.g., the parameter p-maxNR-FR2-target.

11 E-UTRA (evolved universal terrestrial radio access) cell group) maximum total transmit power to be used by UEs, e.g., the parameter p-maxEUTRA.

12 The maximum total transmit power that a UE in the E-UTRA cell group that the UE can use in the source cell group, e.g., the parameter p-maxeeutra-source.

13 A maximum total transmit power that a UE in the E-UTRA cell group can use in the target cell group, e.g., the parameter p-maxeeutra-target.

14 Uplink power sharing Mode (e.g., semi-static Mode 1, semi-static Mode 2, dynamic) used by the UE in DAPS handoff, e.g., parameter uplinkPowerSharingDAPS-Mode.

15 Uplink power sharing Mode (e.g., semi-static Mode 1, semi-static Mode 2, dynamic) used by the UE in FR1 during DAPS handoff, e.g., parameter uplinkpowresharingdaps-Mode-FR 1.

16 Uplink power sharing Mode (e.g., semi-static Mode 1, semi-static Mode 2, dynamic) used by the UE in FR2 during DAPS handoff, e.g., parameter uplinkpowresharingdaps-Mode-FR 2.

17 A maximum Toffset value, e.g., parameter maxtiffset, that the target cell is allowed to use for scheduling target transmissions. It is only used if the uplink power sharing mode is set to dynamic.

3. A serving cell number/range allowing a target node to configure for a target serving cell, comprising at least one of the following indications:

1) The serving cell range, such as the parameter servcellindixrange target, that allows the target node to configure for the target serving cell includes a lower bound and an upper bound for the serving cell index.

2) The maximum number of serving cells that the target node is allowed to configure and the lower limit of serving cell indexes 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-blinddetection target.

5. Measurement coordination information comprising at least one of the following indications:

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

2) The maximum number of allowed measurement identities for inter-frequency measurements, e.g. the parameter maxInterFreqMeaseIdentisTarget, is configured by the allowed target cell

3) The maximum number of allowed measurement identities for on-channel measurement, e.g. the parameter maxIntraFreqMeasIdentisTarget, is allowed for the target cell to be configured on each serving frequency

4) Maximum number of CLI RSSI resources allowing target cell configuration, e.g. parameter maxMeasCLI-resource target

5) Allowing the target cell to configure the maximum number of SRS resources for CLI (Cross Link interference) measurements, e.g. the parameter maxMeasSRS-resource Target

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

7. FR information in the source cell group, e.g., parameter FR-infoslitsource, contains FR information (e.g., FR1 or FR 2) of the serving cell (e.g., PCell, PSCell, SCell) configured in the source cell group.

8. Resource utilization coordination information (or time domain pattern information), which may include a bitmap or bit string, to indicate whether a particular frequency and time resource is intended for use by a source. The target node then assumes that the resources not intended for use by the source are available to the target cell.

Note that in some embodiments, the resource utilization coordination information may be used for handover procedures based on simultaneous connections, but need not be transmitted to and/or received from the source and target cells simultaneously, i.e., the UE may maintain simultaneous connections with the source and target cells and perform reception or/and transmission with the source and target cells at different timings during HO. An example of this type of handover is a TDM (time division multiplexing) based DAPS HO. This type of handoff is hereinafter presented as a TDM-based DAPS HO.

In some embodiments, the source cell includes resource 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 resource utilization coordination information in the HO request confirm message to implicitly indicate or inform the source cell that it accepted the TDM based DAPS HO. In some embodiments, the target cell includes resource utilization coordination information in the HO request confirm message to instruct or inform the source cell to use 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 TDM-based DAPS HOs. In some embodiments, the target cell includes an indication in the HO request confirm message to indicate or inform the source cell whether the target cell accepts the TDM based DAPS HO.

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

In the following paragraphs, an example of using UL resource coordination bit strings or bitmaps is provided with reference to fig. 6.

Each position in the bit string or bitmap represents a Physical Radio Block (PRB) pair in the UL subframe. The value "0" in the bitmap indicates "resources not intended for transmission by the transmitting node", and the value "1" indicates "resources intended for transmission by the transmitting node", and vice versa. The bit string spans N subframes and is n×m bits in length. M is the number of PRBs in a 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 subsequent PRBs in the subsequent subframe in the same order. Each location is applicable only to locations corresponding to UL subframes.

In some embodiments, the same configuration may also be applied to DL resource coordination, where each location is applicable only to locations corresponding to DL subframes.

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

1. UE capability information 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) Band Combination (BC) information, which may be indicated as an index or list of indices pointing to band combinations in MR-DC, CA and/or DAPS capabilities.

3) Featureset uplink/Downlink information, which may be indicated as an index or list of indices (e.g., featureSetDownlinkId, featureSetUplinkId) pointing to the location of Featureset Downlink and/or Featureset uplink.

5) FeaturesetDownlinkPerCC/FeaturesetUpLinkPerCC information, which may be indicated as an index or index list (e.g., parameters FeaturesetDownlinkPerCC-Id and FeaturesetUpLinkPerCC-Id) pointing to the location of FeaturesetDownlinkPerCC and/or FeaturesUpLinkPerCC.

2. FR information in the target cell group, e.g., parameter FR-infoslittarget, contains FR information (e.g., FR1 or FR 2) of the serving cell (e.g., PCell, PSCell, SCell) configured in the target cell group.

3. Power Headroom (PH) information, e.g., parameter PH-infostarget, in the target cell group required for PHR MAC CE is received in the source cell group. The information may include a list of serving cell indexes in the target cell group and a power headroom type (e.g., type 1, type 2, or type 3) for associated serving cells (e.g., PCell and activated SCells), and may also include a power headroom type for the secondary uplink carrier.

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

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

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

3) The UE may request maximum power, e.g., parameter requestedP-Max-Target, for a serving cell in a Target cell group used in the Target cell group.

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

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

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

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

3) The maximum number of requested allowed measurement identities for on-channel measurements is configured on each service frequency, e.g. the parameter requestedwaxmaxintrafreqmeasiditarget.

6. The maximum number of cells that a target node is allowed to request for PDCCH blind-detection configuration, e.g., the parameter requesteddpdcch-blinddetection target.

7. Resource utilization coordination information including at least one of the following indications:

1) A bit string or bitmap to indicate whether the target node is planning to use a particular frequency and time resource. The source node assumes that resources not intended for use by the target are available to the source cell.

2) An offset value indicating an offset of a subframe position or a PRB position in a bitmap or a bit string. The source node assumes that the original bitmap to which the offset applies will 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 from the target node through a handover request message including an RRC message HandoverPrepartionInformation. The handoff request message or RRC message may include the restriction/coordination information to be observed by the target cell during the DAPS handoff. For example, the information may include at least one of the following indications:

UE capability for use in the source cell (e.g., one or more band combinations selected by the source cell, band entries, one or more featureuplink/featuredownlink, one or more featurecombination, one or more featuredownlinkpercc/featureuplink percc);

UE capabilities allowing use by the target cell (e.g., allowing one or more band combinations selected by the source cell, band entries, one or more featureuplink/featuredownlink, one or more featurecombination, one or more featuredownlinkpercc/featureuplink percc);

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

-a serving cell number/range allowing the target node to configure for the target serving cell;

-a maximum number of cells allowing the target node to be configured for PDCCH blind detection;

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

-receiving Power Headroom (PH) information in the source cell group required by the PHR MAC CE in the target cell group; or alternatively

FR information in the source cell group.

Step 2: the target node considers the received restriction/coordination information and generates a target cell configuration that matches the UE capability restriction (i.e., the received restriction/coordination information) during the DAPS HO. The target node sends a handover request confirm message including the generated target cell configuration to the source node.

Aspect 5-example 1a (for aspect 5-option 1): resource utilization coordination

This example is described with reference to fig. 7.

Step 1: the source node requests a DAPS HO to the target node via a handoff request message that can include resource coordination information to indicate whether particular frequency and time resources are intended for use 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 particular 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 alternatively

Reference cell ID for UL and/or DL coordination, e.g. CGI (global cell identity) of the source PCell.

Step 2: the target node generates a corresponding target cell configuration and sends it to the source node via a handover request confirm message. The target node assumes that resources not intended for use 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 available resources.

Aspect 5-example 2 (for aspect 5-option 2):

step 1: the source node requests a DAPS HO to the target node through a 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 a handover request confirm message including an RRC message of the handover command. The handoff request acknowledge message or RRC message may include some of the restriction/coordination information to be observed by the source cell during the DAPS handoff. For example, the information may include at least one of the following indications:

UE capability for use in the target cell (e.g., one or more band combinations selected by the target cell, band entries, one or more featureuplink/featuredownlink, one or more featurecombination, one or more featuredownlinkpercc/featureuplink percc);

-FR information in the target cell group; or alternatively

-receiving Power Headroom (PH) information in the target cell group required by PHR MAC CEs in the source cell group.

Step 3: the source node considers the received restriction/coordination information and generates and sends an updated source cell configuration (e.g., releases one or more source scells or SCGs) to the UE via an RRC reconfiguration message.

Aspect 5-example 2a (for aspect 5-option 2): resource 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 a handover request confirm message. The message may include resource coordination information to indicate whether a particular frequency and time resource is intended for use 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 particular 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 alternatively

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

Step 3: the source node assumes that resources not intended for use by the target cell during the DAPS HO are available to the source cell and schedules the UE based on the available resources.

Aspect 5-example 3 (for aspect 5-option 3):

step 1: step 1 as in aspect 5-example 1.

Step 2 and 3: steps 2 and 3 as in aspect 5-example 2.

Aspect 5-example 3a (for aspect 5-option 3): resource utilization coordination

This example is described with reference to fig. 9.

Step 1: step 1 as in aspect 5-example 1 a.

Step 2: the target node decides to admit the DAPS HO but decides to use or request a new coordination mode. And the target node sends the generated target cell configuration to the source node through the switching request confirmation message. The message may include new resource coordination information to indicate whether a particular frequency and time resource is intended for use by the target cell (as in aspect 5-example 2a, step 2). Or the message may comprise an offset value indication to indicate an offset based on the subframe position or PRB position of a previous pattern that was intended to be used by the source cell.

Step 3: step 3 as in aspect 5-example 2 a.

Aspect 5-example 4 (for aspect 5-option 4):

step 1: step 1 as in aspect 5-example 1.

Step 2: the target node may not meet some constraints/coordinates and/or the target node may decide to request some other resources. The target node rejects the DAPS HO request by sending a handover preparation failure message (or new message) to the source node, which may include an indication or cause value indicating the DAPS HO failure and/or may include request/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 capabilities requested by the target cell in the DAPS HO (e.g., one or more band combinations requested by the target cell, band entries, one or more featureuplink/Downlink, one or more featurelinkage, one or more featuredownlinkpercc/featureuplink percc);

power coordination information requested by the target cell (e.g., maximum power requested by the UE for a serving cell in the target cell group that can be used in the target cell group);

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

-maximum number of cells for which the target node is allowed to request for PDCCH blind detection configuration.

Step 3: the source node considers the received restriction/coordination information and may generate an updated source cell configuration (e.g., release of one or more source scells or SCGs). In addition, the source node may initiate a new handover preparation by sending a new handover request to the target node.

Aspect 5-example 4a (for aspect 5-option 4): resource utilization coordination

This example is described with reference to fig. 10.

Step 1: step 1 as in aspect 5-example 1 a.

Step 2: the target node determines to use or request a new coordination mode and decides to reject the DAPS HO. The target node sends a handover preparation failure message to the source node. The message may include: an indication failure is an indication or cause value caused by a resource coordination failure; and/or requested resource coordination information to indicate whether a particular frequency and time resource is scheduled for use by the target (as in aspect 5-example 2a, step 2); or an offset value indication to indicate an offset based on a subframe location or PRB location of a previous pattern that was scheduled to be used by the source cell to which the offset was applied.

Step 3: the source node initiates a new handover preparation procedure to the target node in consideration of the received resource coordination information.

Aspect 6: performance indication

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

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

alternative 1: the UE sends an indication (e.g., an indicator is included in the UE capabilities information message) to the NW via the UE capability report.

Alternative 2: the NW sends an indication to the UE through dedicated RRC signaling (e.g., including an indicator in an RRC reconfiguration message) or a broadcast message (e.g., including an indicator in an SI message).

In this way, the source node and the target node do UE capability coordination irrespective of the carrier associated with the deactivated or suspended SCell/SCG in the BC, so that the complexity of UE capability coordination may be significantly reduced. Furthermore, the UE does not consider such a configuration to be erroneous.

Fig. 11 relates to a schematic diagram of a wireless communication terminal 30 (e.g., a terminal node or 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 computer, a tablet computer, an electronic book, or a portable computer system, and is not limited thereto. The wireless communication terminal 30 may include a processor 300, such as a microprocessor or an Application Specific Integrated Circuit (ASIC), a storage unit 310, and a communication unit 320. The memory unit 310 may be any data storage device that stores program code 312 that is accessed and executed by the processor 300. Examples of stored 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 devices. The communication unit 320 may be a transceiver and is configured to transmit and receive signals (e.g., messages or data packets) according to the processing result of the processor 300. In one embodiment, communication unit 320 transmits and receives 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 having stored program code.

The processor 300 may implement any of the steps of the exemplary embodiments on the wireless communication terminal 30, for example, by executing the program code 312.

The communication unit 320 may be a transceiver. Alternatively or additionally, the communication unit 320 may combine a transmitting unit and a receiving unit configured to transmit and receive signals to and from the wireless communication node, respectively.

In some embodiments, the wireless communication terminal 30 may be configured to perform the operations of the UE described above. In some embodiments, processor 300 and communication unit 320 cooperate to perform the operations described above. For example, the processor 300 performs operations and transmits or receives signals, messages, and/or information through the communication unit 320.

Fig. 12 relates to a schematic diagram of a wireless communication node 40 (e.g., a network device) in accordance with 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), a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), a Radio Access Network (RAN), a next generation RAN (NG-RAN), a data network, a core network controller, or a Radio Network Controller (RNC), and is not limited in this regard. Further, 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 Retrieval Function (LRF), a User Plane Function (UPF), a Policy Control Function (PCF), an Application Function (AF), and the like. The wireless communication node 40 may comprise a processor 400, such as a microprocessor or ASIC, a storage unit 410, and a communication unit 420. The memory unit 410 may be any data storage device that stores program code 412 that is accessed and executed by the processor 400. Examples of storage units 412 include, but are not limited to, SIM, ROM, flash memory, RAM, hard disk, and optical data storage devices. The communication unit 420 may be a transceiver and is configured to transmit and receive signals (e.g., messages or data packets) according to the processing result of the processor 400. In one example, communication unit 420 transmits and receives signals via at least one antenna 422.

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

Processor 400 may implement any of the steps described in the exemplary embodiments on wireless communication node 40, for example, via execution of program code 412.

The communication unit 420 may be a transceiver. Alternatively or additionally, the communication unit 420 may combine a transmitting unit and a receiving unit configured to transmit and receive signals, messages or information to and from the wireless communication terminal, respectively.

In some embodiments, wireless communication node 40 may be configured to perform the operations of the source node or the target node described above. In some embodiments, processor 400 and communication unit 420 cooperate to perform the operations described above. For example, the processor 400 performs operations and transmits or receives 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., UE).

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

Operation S11 comprises receiving, by the wireless communication terminal, a handover command from the first wireless communication node indicating to use the simultaneous connection based handover. In an embodiment, the first wireless communication node may be the source node described above. The handover command may 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 an embodiment, the first wireless communication node may be the target node described above.

Operation S13 includes maintaining, by the wireless communication terminal, a connection with the first wireless communication node until the handover procedure is completed.

Details of this may be determined with reference to the above paragraphs and are not repeated here.

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 one embodiment, the wireless communication method includes operation S21.

Operation S21 comprises transmitting, by the first wireless communication node, a handover command to the wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous connection-based handover from the first wireless communication node to the 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 limitation. Likewise, the various figures may depict exemplary architectures or configurations provided to enable those of ordinary skill in the art to understand the exemplary features and functions of the present disclosure. However, those skilled in the art will appreciate that the present disclosure is not limited to the example architectures or configurations shown, but may be implemented using a variety of alternative architectures and configurations. Furthermore, as will be appreciated by one of ordinary skill in the art, one or more features of one embodiment may 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 of the above-described exemplary embodiments.

It will be further understood that any reference herein to elements using designations such as "first," "second," etc. generally does not limit the number or order of such elements. Rather, these reference names may be used herein as a convenient means of distinguishing between two or more elements or multiple instances of an element. Thus, references to first and second elements do not mean that only two elements can be used or that the first element must somehow precede the second element.

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

Those of skill would further appreciate that any of the various illustrative logical blocks, units, processors, devices, circuits, methods, and functions described in connection with the aspects disclosed herein may be implemented with electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of both), firmware, various forms of program or design code incorporating instructions (which may be referred to herein as "software" or "a software unit" for convenience), 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 as a combination of such techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. According to various embodiments, processors, devices, components, circuits, structures, machines, units, etc. may be configured to perform one or more of the functions described herein. The term "configured" 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.

Moreover, those of skill in the art will appreciate that the various illustrative logical blocks, units, devices, components, and circuits described herein may be implemented within or performed by an Integrated Circuit (IC) that may comprise 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. Logic blocks, units, and circuits may also include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, or state machine. A processor may 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, these functions may be stored on a computer-readable medium as one or more instructions or code. Thus, the steps of a method or algorithm disclosed herein may be embodied as software stored on a computer readable medium.

Computer-readable media includes both computer storage media and communication media including any medium that can transfer a computer program or code from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise 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. In addition, for purposes of discussion, the various units are described as discrete units; however, as will 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 function in accordance with embodiments of the disclosure.

Additionally, memory or other storage and communication components may be used in embodiments of the present disclosure. It should be appreciated that for clarity, the above description has described embodiments of the disclosure with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality may be applied between different functional units, processing logic elements, or domains without departing from the present disclosure. For example, functions illustrated as being performed by separate processing logic elements or controllers may be performed by the same processing logic element or controller. Thus, references to specific functional units are only references to suitable means for providing the functionality, and do not represent strict logical or physical structures 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 may be applied to other implementations without departing from the scope of this disclosure. Thus, the present disclosure is not limited to the implementations shown herein but is to be accorded the widest scope consistent with the novel features and principles disclosed herein as described in the following claims.

Claims

1. A method of wireless communication, comprising:

the wireless communication terminal receiving a handover command from the first wireless communication node indicating to use a handover based on the simultaneous connection; and

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

the wireless communication terminal maintains a connection with the first wireless communication node until the handover procedure is completed.

2. The wireless communication method of claim 1, wherein the handover command comprises at least one of:

a first indication of an activation status for at least one of the target secondary cell SCel or the target secondary cell group SCG; or (b)

A first trigger condition for activation of at least one of the target SCel or target SCG.

3. The wireless communication method according to claim 1 or 2, further comprising:

before receiving the handover command, the wireless communication terminal receives a radio resource control, RRC, message from the first wireless communication node, wherein the RRC message includes at least one of: a second indication of an activation state for at least one of the source SCel or the source SCG; or a second trigger condition for activation of at least one of the source SCel or the source SCG.

4. A wireless communication method according to any one of claims 1 to 3, further comprising wherein in response to at least one of: the wireless communication terminal performs at least one of the following when receiving the handover command, or when receiving the first indication of the activation state for at least one of the target SCel or the target SCG, or when receiving the second indication of the activation state for at least one of the source SCel or the source SCG:

the wireless communication terminal transitions the at least one of the source SCel, the source SCG, the target SCel, or the target SCG from an active state to a deactivated state, a dormant state, or a suspended state; or alternatively

The wireless communication terminal configures the at least one of the source SCel, the source SCG, the target SCel, or the target SCG to a deactivated state, a dormant state, or a suspended state.

5. The wireless communication method according to any one of claims 1 to 4, further comprising:

the wireless communication terminal activates or resumes at least one of the target SCel or the target SCG in response to completion of the handover procedure, wherein the at least one of the target SCel or the target SCG is in a deactivated state, a dormant state, or a suspended state during the handover procedure.

6. The wireless communication method according to any one of claims 1 to 4, further comprising:

in response to successful completion of random access to a target primary cell, PCel, the wireless communication terminal activates or resumes at least one of the target SCel or the target SCG, wherein the at least one of the target SCel or the target SCG is in a deactivated state, a dormant state, or a suspended state during the handover before successful completion of random access to the target PCel.

7. The wireless communication method of claim 5 or 6, wherein the at least one of the target SCel or target SCG is activated in response to a first trigger condition in the handover command for the corresponding target SCel or target SCG being met.

8. The wireless communication method of claim 7, wherein the wireless communication terminal begins evaluating at least one first trigger condition for at least one of the target SCel or the target SCG in response to receiving at least one of the handover command, successful completion of random access to target PCel, or successful completion of a handover procedure.

9. The wireless communication method according to any one of claims 1 to 4, further comprising:

in response to the wireless communication terminal backing up to the source cell upon detection of a handover failure, the wireless communication terminal activates or resumes at least one of the source SCel or the source SCG.

10. The wireless communication method of claim 9, wherein the at least one of the source SCel or the source SCG is activated in response to the second trigger condition for the corresponding source SCel or source SCG being met.

11. The wireless communication method of claim 10, wherein the wireless communication terminal begins evaluating at least one second trigger condition for at least one of the source SCel or the source SCG in response to at least one of receiving the RRC message or when the wireless communication terminal rolls back to the source cell.

12. The wireless communication method of claim 1, wherein in response to detecting a failure of the source SCel or the source SCG 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 SCel or the source SCG;

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

releasing the connection of the source SCel l or the source SCG; or alternatively

Releasing the configuration of the source SCel l or the source SCG.

13. The wireless communication method of claim 1, further comprising:

in response to the number of cells configured to the wireless communication terminal exceeding the capabilities of the wireless communication terminal, the wireless communication terminal deactivates or suspends at least one of source SCel l, source SCG, target SCel l, or target SCG.

14. The wireless communication method of claim 1, further comprising:

the wireless communication terminal leaves the source cell in response to the number of cells configured to the wireless communication terminal exceeding the capability of the wireless communication terminal.

15. The wireless communication method of claim 1, further comprising:

the wireless communication terminal sends an indication to the network node indicating that the total number of carriers of at least one of source SCel, source SCG, target SCel or target SCG during the capability coordination procedure is not counted in the capability calculation of the wireless communication terminal,

Wherein during the handover procedure, the at least one of the source SCel, the source SCG, the target SCel, or the target SCG is deactivated or suspended.

16. The wireless communication method of claim 1, further comprising:

the wireless communication terminal receives an indication from a network node that the total number of carriers of at least one of source SCel, source SCG, target SCel or target SCG during a capability coordination procedure is not counted in a capability calculation of the wireless communication terminal,

17. A method of wireless communication, comprising:

the first wireless communication node sends a handover command to the wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous connection-based handover from the first wireless communication node to a second wireless communication node.

18. The wireless communication method of claim 17, wherein the handover command comprises at least one of: a first indication of an activation status for at least one of the target secondary cell SCel or the target secondary cell group SCG; or a first trigger condition for activation of at least one of the target SCel or target SCG.

19. The wireless communication method of claim 17, further comprising:

before receiving the handover command, the first wireless communication node transmits a radio resource control, RRC, message, wherein the RRC message includes at least one of: a second indication of an activation state for at least one of the source SCel or the source SCG; or a second trigger condition for activation of at least one of the source SCel or the source SCG.

20. The wireless communication method of claim 17, further comprising:

an indication is sent by the first wireless communication node to the wireless communication terminal to instruct the wireless communication terminal to deactivate or suspend at least one of source SCel, source SCG, target SCel, or target SCG in response to the number of cells configured to the wireless communication terminal exceeding the capabilities of the wireless communication terminal.

21. The wireless communication method of claim 17, further comprising:

the first wireless communication node sends an indication to the wireless communication terminal to instruct the wireless communication terminal to leave a source cell in response to the number of cells configured to the wireless communication terminal exceeding the capabilities of the wireless communication terminal.

22. The wireless communication method of claim 17, further comprising:

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

23. 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 during a capability coordination procedure, a number of carriers of at least one of a source SCel, a source SCG, a target SCel, or a target SCG is not counted in a total number of configuration carriers of the wireless communication terminal,

24. A wireless communication terminal, comprising:

A communication unit; and

a processor configured to:

receiving, by the wireless communication terminal, a handover command from the first wireless communication node indicating to use a handover based on the simultaneous connection; and

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

25. The wireless communication terminal of claim 24, wherein the processor is further configured to perform the wireless communication method of any of claims 2 to 16.

26. A wireless communication node, comprising:

a communication unit; and

a processor configured to:

a handover command is sent by a first wireless communication node to a wireless communication terminal to instruct the wireless communication terminal to perform a simultaneous connection-based handover from the first wireless communication node to a second wireless communication node.

27. The wireless communication node of claim 26, wherein the processor is further configured to perform the wireless communication method of any of claims 18-23.

28. A computer program product comprising computer readable program medium code stored thereon, which when executed by a processor causes the processor to implement the wireless communication method according to any of claims 1 to 23.