CN117730566A

CN117730566A - Dual active protocol stack handover with controlled secondary cell release

Info

Publication number: CN117730566A
Application number: CN202280050896.7A
Authority: CN
Inventors: S·赛瓦加纳帕西; A·阿里; A·阿瓦达; J·斯坦科扎克
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2021-08-04
Filing date: 2022-07-08
Publication date: 2024-03-19
Also published as: EP4381803A1; WO2023011852A1

Abstract

An apparatus, method, computer program, non-transitory computer readable medium, user equipment, source node, target node, network, and system are provided. In at least some examples, the reconfiguration information is sent for execution by the user equipment. The reconfiguration information includes dual active protocol stack DAPS handoff information. The DAPS handoff information includes secondary cell release information to enable: based on receiving the DAPS handoff information at the user device, a secondary cell release from the source protocol stack is initiated at a defined trigger point during execution of the DAPS handoff.

Description

Dual active protocol stack handover with controlled secondary cell release

Technical Field

Examples of the present disclosure relate to dual active protocol stack DAPS handoff with controlled secondary cell release.

Background

Dual active protocol stack handoff (DAPS handoff) is a handoff procedure that maintains a connection to a source node after receiving a reconfiguration message for handoff and until the source node is released after successful random access to a target node.

DAPS handover was introduced in 3GPP release 16 to achieve reduced interruption times, approaching 0 ms. As part of the DAPS handoff, a User Equipment (UE) configures two simultaneous protocol stack instances with a source cell group and a target cell group to enable radio transmission/reception via the two cell groups without interruption.

Between handovers, some UEs are configured to concurrently utilize radio resources provided by a set of serving cells including a primary cell and one or more secondary cells. The secondary cell cannot be used at the time of DAPS handoff and will be released before the DAPS handoff command is issued to the UE.

Disclosure of Invention

According to various, but not necessarily all, examples of the disclosure there is provided an apparatus comprising means for:

receiving reconfiguration information for user equipment to execute, wherein the reconfiguration information comprises dual-active protocol stack DAPS switching information, and the DAPS switching information comprises secondary cell release information; and

based on receiving DAPS handoff information with secondary cell release information, a DAPS handoff is initiated that includes releasing the secondary cell from the source protocol stack at a defined trigger point during execution of the DAPS handoff.

According to various, but not necessarily all, examples of the disclosure there is provided a method comprising:

According to various, but not necessarily all, examples of the disclosure there is provided a computer program that, when run by a computer, causes:

According to various, but not necessarily all, examples of the disclosure there is provided a non-transitory computer-readable medium encoded with instructions that, when executed by at least one processor, cause at least the following to be performed:

According to various, but not necessarily all, examples of the disclosure there is provided an apparatus comprising:

at least one processor; and

at least one memory including computer program instructions;

the at least one memory and the computer program instructions are configured to, with the at least one processor, cause the apparatus at least to perform:

According to various, but not necessarily all, examples of the disclosure, the apparatus is a user equipment apparatus for controlling a user equipment.

According to various, but not necessarily all, examples of the disclosure there is provided a user equipment, wherein the user equipment is the apparatus.

The following section of the "summary of the invention" section describes various features, which may be features of any of the examples described in the foregoing section of the "summary of the invention. The description of a function should be taken as disclosing also any component suitable for performing the function.

In some, but not necessarily all, examples, the reconfiguration information includes a reconfiguration message that includes DAPS handoff information with secondary cell release information.

In some, but not necessarily all, examples, the apparatus comprises means for transmitting capability information to a network node, the capability information indicating whether a user equipment has a capability to receive DAPS handoff information with secondary cell release information, wherein the secondary cell release information is included in the received reconfiguration information depending on the user equipment having the capability.

In some, but not necessarily all, examples, the defined trigger point is configured to be reached before instantiation of the target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferred trigger point configured to be reached after instantiation of the target protocol stack during execution of the DAPS handoff.

In some, but not necessarily all examples, deferred trigger points depend on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

In some, but not necessarily all, examples, the secondary cell release information includes trigger point information that at least partially identifies a defined trigger point.

In some, but not necessarily all, examples, the defined trigger point comprises a default trigger point if the secondary cell release information does not include trigger point information that at least partially identifies the defined trigger point.

In some, but not necessarily all, examples, the default trigger point includes random access completion and/or is dependent on initiation of an uplink handover.

transmitting reconfiguration information for execution by the user equipment, wherein the reconfiguration information includes dual active protocol stack DAPS handoff information, wherein the DAPS handoff information includes secondary cell release information to enable initiation of release from a secondary cell of the source protocol stack at a defined trigger point during execution of the DAPS handoff based on receipt of the DAPS handoff information at the user equipment.

At least one processor; and

at least one memory including computer program instructions;

the at least one memory and the computer program instructions are configured to, with the at least one processor, cause the apparatus at least to perform

According to various, but not necessarily all, examples of this disclosure the apparatus is a network node apparatus that comprises means for operating as a source node prior to completion of execution of a DAPS handoff.

According to various, but not necessarily all, examples of the disclosure there is provided a source node, wherein the source node is the apparatus.

In some, but not necessarily all, examples, the apparatus comprises means for receiving capability information indicating whether the user equipment has a capability to receive DAPS handoff information with secondary cell release information, wherein the secondary cell release information is included in the transmitted reconfiguration information depending on the user equipment having the capability.

In some, but not necessarily all, examples, the apparatus comprises means for sending a DAPS handoff request to the target node, the DAPS handoff request comprising a flag indicating whether DAPS handoff information should include secondary cell release information.

In some, but not necessarily all, examples, the apparatus comprises means for receiving a handoff request acknowledgement in response to a DAPS handoff request, the handoff request acknowledgement comprising DAPS handoff configuration information with a secondary cell release information element.

In some, but not necessarily all, examples, the apparatus comprises means for operating as a source node that provides radio resources to a user equipment utilizing carrier aggregation via a set of serving cells including a primary cell and one or more secondary cells, and continues to operate as a source node utilizing carrier aggregation with the primary cell and the one or more secondary cells after receiving a handoff request acknowledgement and until a secondary cell release is performed during performance of a DAPS handoff.

In some, but not necessarily all, examples, the apparatus comprises means for determining a defined trigger point that controls when secondary cell release should be initiated during execution of the DAPS handoff, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

In some, but not necessarily all, examples, determining the defined trigger point includes determining which trigger point of the plurality of trigger points the trigger point information will indicate.

receiving a DAPS switching request for dual-active protocol stack DAPS switching of user equipment; and

In response, a handoff request acknowledgement is sent, the handoff request acknowledgement including DAPS handoff configuration information having a secondary cell release information element for releasing a secondary cell from a source protocol stack at a defined trigger point during execution of a DAPS handoff based on the DAPS handoff configuration information.

at least one processor; and

at least one memory including computer program instructions;

According to various, but not necessarily all, examples of this disclosure the apparatus is a network node apparatus that comprises means for operating as a target node prior to completion of execution of a DAPS handoff.

According to various, but not necessarily all, examples of the disclosure there is provided a target node, wherein the target node is the apparatus.

In some, but not necessarily all, examples, the DAPS handoff request includes a flag indicating whether reconfiguration information to be sent for user equipment execution based on the handoff request acknowledgement should include secondary cell release information, and wherein the secondary cell release information element depends on the flag.

In some, but not necessarily all, examples, the apparatus comprises means for sending reconfiguration information comprising source protocol stack release information to the user equipment to cause, at least in part, initiation of release of the source protocol stack.

In some, but not necessarily all, examples, the apparatus comprises means for determining or modifying a defined trigger point that controls when secondary cell release should be initiated during execution of a DAPS handoff, wherein the handoff request acknowledgement comprises trigger point information that at least partially identifies the determined or modified defined trigger point.

In some, but not necessarily all, examples, determining or modifying the defined trigger point includes determining which trigger point of the plurality of trigger points the trigger point information will indicate.

According to various, but not necessarily all, examples of the disclosure there is provided a network comprising a source node and a target node.

According to various, but not necessarily all, examples of the disclosure there is provided a system comprising a network and a user equipment.

According to various, but not necessarily all, embodiments, examples are provided as claimed in the appended claims.

The description of a function and/or action should be taken as also disclosing any component suitable for performing the function and/or action.

Drawings

Some examples will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates one example of the subject matter described herein;

FIG. 2 illustrates another example of the subject matter described herein;

FIG. 3 illustrates another example of the subject matter described herein;

FIG. 4 illustrates another example of the subject matter described herein;

FIG. 5 illustrates another example of the subject matter described herein;

6A, 6B, 6C illustrate another example of the subject matter described herein;

FIG. 7 illustrates another example of the subject matter described herein;

FIG. 8 illustrates another example of the subject matter described herein;

9A, 9B illustrate another example of the subject matter described herein;

FIG. 10 illustrates another example of the subject matter described herein;

FIG. 11 illustrates another example of the subject matter described herein; and

fig. 12 illustrates another example of the subject matter described herein.

Definition of the definition

3GPP: third generation partnership project

AS: access stratum

CA: carrier aggregation

DAPS: dual active protocol stack

DC: dual connection

eNB：eNodeB

E-UTRA: evolved universal terrestrial radio access

E-UTRAN: evolved universal terrestrial radio access network

gNB：gNodeB

gNB-CU: gNodeB centralized unit

gNB-DU: gNodeB distributed unit

HO: handover

MAC: media access control layer

MCG: master cell group

MN: main node

MR-DC: multi-radio dual connectivity

NAS: non-access stratum

NR: new radio

PCell: main cell

PDCP: packet data convergence protocol

PHY: physical layer

PRACH: physical random access channel

PS: protocol stack

PSCell: primary and secondary cells

RACH: random access channel

RAN: radio access network

RAT: radio access technology

RLC: radio link control

RRC: radio resource control

SCell: secondary cell

SCG: secondary cell group

SN: auxiliary node

UE: user equipment

UL: uplink channel

Detailed Description

Fig. 1 shows an example of a network 100, the network 100 comprising a plurality of network nodes including a terminal node 110, an access node 120 and one or more core nodes 129. Terminal node 110 and access node 120 communicate with each other. One or more core nodes 129 communicate with access node 120.

In this example, the network 100 is a telecommunication network in which at least some of the terminal nodes 110 and the access nodes 120 communicate with each other using transmission/reception of radio waves/signals.

In some examples, one or more core nodes 129 may communicate with each other. In some examples, one or more access nodes 120 may communicate with each other.

In some examples, one or more end nodes 110 may communicate with each other.

Network 100 may be a cellular network including a plurality of cells 122, at least one cell 122 being served by access node 120. In this example, the interface between the terminal node 110 and the access node 120 defining the cell 122 is a wireless interface 124.

Access node(s) 120 are cellular radio transceivers. End node 110 is a cellular radio transceiver.

In the illustrated example, cellular network 100 is a third generation partnership project (3 GPP) network, where end node 110 is a User Equipment (UE) and access node 120 is a base station (e.g., a gNB).

The term "node" in the following examples refers to an access node. In the 3GPP defined system 1, the access node is a base station. The base station implementing NR is called a gNB. A base station implementing a different RAT, such as E-UTRA, is called an eNB.

In some examples, the network 100 is a next generation (or new radio NR) radio access network (NG-RAN) according to a fifth generation (5G) standard. The NG-RAN includes the gNB to provide user plane and control plane (e.g., RRC) protocol termination towards the mobile device 110. The gNBs are interconnected with each other through X2/Xn interface 126. The gNB is also connected to an access and mobility management function (AMF) through an N2 interface 128.

Fig. 2 shows an example of a gNB 120 configured to implement NR. In this example, node 120 has a split (split) architecture. The gNB 120 includes one or more distributed units (gNB-DUs) 20 and a centralized unit (gNB-CU) 10. The apparatus 2 is configured to implement a function of at least a portion of the node 120, such as a gNB-CU, and/or one or more gNB-DUs, or the entire gNB.

As shown in fig. 2, the functionality of the gNB base station may be distributed between a central unit (e.g., a gNB-CU) and one or more Distributed Units (DUs) (e.g., a gNB-DU).

The gNB-CU 10 is a logical node configured to host a radio resource control layer (RRC) and other layers of the gNB 120. The gNB-CU 10 controls the operation of one or more gNB-DUs 20. The gNB-DU 20 is a logical node configured to host a radio link control protocol layer (RLC), a medium access control layer (MAC), and a physical layer (PHY) of the access node (gNB) 120. The gNB-DU 20 communicates with the RRC layer hosted by the gNB-CU via a dedicated interface (F1).

One gNB-DU 20 may support one or more cells (not shown). One cell is supported by only one gNB-DU 20.

In some examples, the network 100 is E-UTRAN. The E-UTRAN includes an E-UTRAN eNB to provide for E-UTRA user plane and control plane (e.g., RRC) protocol termination towards the UE 110. The enbs 120 are interconnected to each other by an X2 interface 126. The eNB is also connected to a Mobility Management Entity (MME) 129 through an S1 interface 128. The core network may also include a serving gateway (S-GW).

Fig. 3 shows an example of an eNB 120 configured to implement E-UTRA. In this example, node 120 does not have a split architecture. The eNB 120 is a logical node configured to host a radio resource control layer (RRC) and other layers of the eNB 120. The apparatus 2 is configured to implement the functionality of at least a portion of a node 120, such as an eNB.

In at least some examples, a node includes a cell group of one or more cells. The cell group includes a primary cell and zero or more secondary cells.

A cell relates to a geographical area with radio signals, i.e. a geographical area in which UEs 110 covered by a base station may connect and acquire service. Cells may be identified by a low-level Physical Cell Identity (PCI) and a high-level cell identity.

The primary cell is a cell operating on a primary frequency in which the UE 110 performs an initial connection establishment procedure or initiates a connection re-establishment procedure, or is a cell indicated as the primary cell in a handover procedure. In at least some examples, the primary cell is a cell configured to provide non-access stratum (NAS) mobility information during connection establishment, reestablishment, or handover. The primary cell may be configured to provide security input during connection reestablishment or handover.

The secondary cell is a cell operating on the secondary frequency, which may be configured after RRC connection establishment and may be used to provide additional radio resources. A secondary cell (SCell) may be configured to form a serving cell set with a PCell.

In an example, the network 100 may include a combination of RANs such as E-UTRAN and NG-RAN. In an example, the network 100 is configured to enable multi-connection operation to enable simultaneous use of two RATs (NR, E-UTRA) by the same UE 110. Multi-radio dual connectivity (MR-DC) is a multi-connectivity 3GPP example.

During multiple connections, one node 120 to which UE 110 is operably coupled may be configured to act as a Master Node (MN). Another node 120 to which UE 110 is simultaneously operatively coupled may be configured to act as a Secondary Node (SN). In some, but not necessarily all, examples, the SN 120 implements a different RAT than the MN 120.

In a multi-connection (e.g., MR-DC), the cell group of MN 120 is the Master Cell Group (MCG). The cell group of SN 120 is a Secondary Cell Group (SCG). The MCG includes a primary cell (PCell) and zero or more secondary cells (scells). The SCG includes a primary secondary cell (PSCell) and zero or more secondary cells (scells). In at least some examples, the MCG and SCG include at least one SCell in addition to the PCell or PSCell.

When multiple connections are first established, UE 110 stores the configuration in memory. The configuration includes information identifying an MCG including a PCell and zero or more scells and an SCG including a PSCell and zero or more scells, and one or more bearers. A bearer is a data tunnel associated with an endpoint in the RAN or core network.

The configuration may include one or more of the following: information for measurement configuration; information for mobility control; radio resource configuration information (including radio bearers, MAC master configuration and physical channel configuration); and/or Access Stratum (AS) security configuration.

After application (execution) of the configuration, UE 110 may be configured to receive and transmit data over MCG and SCG bearers using radio links provided by the MN and SN.

Fig. 4 is a message sequence chart illustrating an example of a method 400. Method 400 illustrates an example of DAPS handoff feature operation without involving the timing of the release of secondary cells considered later in fig. 7-10.

In an example, a terminal node (UE) 110 can be configured to perform and can perform a DAPS handoff from a first access node 120a, which can be considered a source node, to a second access node 120b, which can be considered a target node.

In an example, fig. 4 may be considered to illustrate various approaches. For example, FIG. 4 illustrates one or more actions at multiple actors/entities. In an example, fig. 4 may be considered to illustrate a number of methods performed by an individual actor/entity.

In the example of fig. 4, a plurality of devices send and/or receive one or more signals and/or one or more messages through and/or via and/or using a network. In an example, any suitable form of communication in any suitable network may be used. For example, at least a portion of the network 100 of fig. 1 may be used.

Thus, in an example, the plurality of devices in fig. 4 form at least a portion of the network 100 as described with respect to fig. 1.

In the illustrated example, the end node 110, the first access node 120a, and the second access node 120b send and/or receive one or more signals and/or one or more messages. In an example, the first access node 120a may be considered a source node and the second access node 120b may be considered a target node.

In an example, communication and/or transmission between the elements shown in fig. 4 may occur via any number of intervening elements, including the absence of intervening elements.

In an example, method 400 and/or portions of method 400 can be considered a method of enabling Dual Active Protocol Stack (DAPS) handoff.

In some examples, method 400 and/or portions of method 400 can be considered a method that supports Dual Active Protocol Stack (DAPS) handoff.

In some examples, method 400 and/or portions of method 400 can be considered a method of performing Dual Active Protocol Stack (DAPS) handoff.

In the example of fig. 4, a radio connection is established between the terminal node 110 and the first access node 120a, which may be considered a source node.

In the illustrated example, a DAPS handoff will occur from a first access node 120a to a second access node 120b, which may be considered a target node.

Block 402 includes UE 110 transmitting a measurement ("measurement report") to source node 120 a. The measurements may include signal power and/or signal quality measurements, such as Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ).

The measurement report may indicate possible mobility of UE 110 from source node 120a to target node 120 b. For example, UE 110 may transfer from a source cell (e.g., source PCell) associated with source node 120a to a target cell (e.g., target PCell) associated with target node 120 b.

Block 404 includes source node 120a initiating a DAPS handoff. The decision to initiate a DAPS handoff may be based at least in part on the measurements described above. It should be appreciated that the decision to initiate a handover may occur elsewhere than at the source node.

More specifically, block 404 includes: if acknowledgement and/or DAPS handoff configuration information is needed from target node 120b, source node 120a sends a DAPS handoff request message to target node 120 b. The target node 120b may be selected by the source node 120a based at least in part on the measurement report from the UE 110. The target node may be one candidate target node of a set of one or more candidate target nodes to which the request is sent.

Block 406 includes DAPS admission control operations performed at the target node 120 b.

At block 408, the target node 120b transmits a handoff request acknowledge message to the source node 120a in response to the DAPS handoff request message. The handoff request confirm message includes DAPS handoff configuration information. The DAPS handoff configuration information may include at least some of the information described with respect to fig. 5. In an example, the DAPS handoff configuration information can be considered a DAPS handoff command prepared at least in part by the target node 120 b. In an example, the DAPS handoff configuration information can be provided in a DAPS handoff container to be sent to source node 120 a.

At block 410, source node 120a sends reconfiguration information to UE 110 for execution by UE 110, where the reconfiguration information includes DAPS handoff information associated with the DAPS handoff configuration information.

In an example, the DAPS handoff information sent to UE 110 is based on DAPS handoff configuration information received from target node 120 b. In an example, the DAPS handoff information sent to UE 110 can comprise at least a portion of the DAPS handoff configuration information received from target node 120 b. In an example, block 410 includes forwarding at least a portion of the DAPS handoff configuration information received from target node 120b to UE 110.

The reconfiguration information may take the form of an RRC reconfiguration message (DAPS configuration) and may be a DAPS handover command (DAPS HO). The message prompts (triggers) UE 110 to perform the DAPS handoff mobility procedure.

In an example, the source node 120a sends a DAPS handoff command to the UE 110 based on having received DAPS handoff configuration information from the target node 120 b.

At block 412, user data is exchanged between UE 110 and source node 120 a. In an example, exchanging user data includes UE 110 continuing user plane data transmission/reception with source node 120a (occurring in parallel with block 410, and this is normal operation of UE 110).

At block 414, a data forwarding message is sent from source node 120a to target node 120 b. The data forwarding message may include information associated with the user data.

At block 416, the UE 110 initiates a DAPS handoff ("DAPS operation begins"). UE 110 performs the DAPS handoff at least in part.

The DAPS handoff begins at block 418 of method 400 and completes at block 436 of method 400.

At block 418, user data is exchanged between UE 110 and source node 120 a.

Between blocks 416 and 434, UE 110 configures two simultaneous PS instances simultaneously, including a source PS and a target PS. The two active protocol stacks enable user plane radio transmission/reception via two cell groups without interruption.

At block 420, ue 110 sends a Physical Random Access Channel (PRACH) preamble message to target node 120 b.

At block 422, the target node 120b transmits a Random Access Channel (RACH) response message to the UE 110 in response to the PRACH preamble message.

At block 424, ue 110 sends reconfiguration information in the form of an RRC reconfiguration complete message to target node 120 b.

At block 426, the target node 120b sends a handover success message to the source node 120a in accordance with having received the RRC reconfiguration complete message.

At block 428, source node 120a ceases transmitting to UE 110/receiving from UE 110 based on having received the handover success message.

At block 430, the source node 120a sends an SN state transfer message to the target node 120b in accordance with the success of the handoff (blocks 426/428). In an example, the SN state transfer message causes the state to be updated such that the target node 120b becomes the new source node 120a.

At block 432, target node 120b sends reconfiguration information including source PS release information to UE 110. The reconfiguration information may take the form of an RRC reconfiguration message (source PS release) that is sent in accordance with having received the SN state transfer message.

In an example, an RRC reconfiguration message (source PS release) is used as a command to prompt (trigger) UE 110 to release its source PS. After releasing the source PS, the single target PS is active.

At block 434, ue 110 releases source PS according to the indication.

At block 436, ue 110 sends reconfiguration information in the form of an RRC reconfiguration complete message to target node 120 b. This indicates that the source PS has been released.

At block 438, user data is exchanged between UE 110 and target node 120 b.

The problem with DAPS handoff is that the undesirable source protocol PS has secondary cells configured upon receipt of the DAPS HO command (block 410). Nor is it expected that the DAPS HO command (block 410) have any secondary cell related configuration for the target cell. Only the source and target PCell are used during DAPS handoff. As shown in block 432, RRC reconfiguration is required to release the source PS, and then UE 110 releases in block 434. A new RRC reconfiguration message may be sent to add the SCell(s) to the target PCell after releasing the source PS, or, at the earliest, in conjunction with the source PS release message of block 432.

An example method 500 of UE 110 processing a DAPS handoff command at block 416 is illustrated in fig. 5. In summary, processing the RRC reconfiguration message at block 416 includes updating configuration information for the UE 110 based on the DAPS handoff information provided in the RRC reconfiguration message. UE 110 stores the configuration information in memory. The configuration information includes one or more of the following:

-an MCG configuration identifying an MCG comprising a PCell and zero or more scells;

-an SCG configuration identifying an SCG comprising a PSCell and zero or more scells;

-an Access Stratum (AS) security configuration; and

radio resource configuration information (including radio bearer configuration, MAC master configuration and physical channel configuration).

Block 502 includes updating the MCG configuration. Example steps of processing the MCG configuration are shown in sub-blocks 512-520 shown in fig. 5, which are described later.

The blocks 504 associated with the SCG and SCG configuration are marked with dashed lines because they are not applicable to DAPS handoff. Fig. 5 depicts DAPS handoff execution with only the source PCell and the target PCell.

Block 506 includes updating the AS security key configuration.

Block 508 includes updating the radio bearer configuration. In an example, this includes reconfiguring PDCP for DAPS handoff at block 509.

Block 510 includes forwarding of the dedicated NAS.

In an example, sub-block 512 of block 502 includes performing the "reconfiguration with synchronization" portion of the RRC reconfiguration message. Example steps of processing reconfiguration with synchronization are shown in sub-blocks 522-528 shown in fig. 5. In an example, sub-blocks 522-528 of block 512 include one or more of the following:

at block 522, a MAC instance is created for the target node 120b (target cell).

At block 524, an RLC instance is created for the target node 120b for each DAPS bearer.

-at block 526, assigning a Radio Network Temporary Identifier (RNTI) to the target PS.

At block 528, the SPCell public and private configurations are applied to the target cell. The SPcell refers to a primary and secondary cell (SPcell of a secondary cell group) in MR-DC.

The remaining sub-blocks 514-520 of block 502 include:

at block 514, RLC bearer reconfiguration is performed. In an example, this includes modifying the target RLC in the RLC bearer configuration at block 530.

At block 516, MAC configuration is performed. In an example, this includes modifying the target MAC in the MAC configuration at block 532.

Block 520 associated with SCG and SCG configuration is marked with a dashed line, as in some examples they are not applicable to DAPS handoff.

Fig. 6A-6C illustrate the source PS and target PS at different stages of progression through fig. 5 when the target PS instance is activated (instantiated).

Fig. 6A illustrates a first phase (e.g., block 512 of fig. 5) that includes creation of MAC, RLC, and physical layer instances of the target PS (e.g., blocks 522, 524 of fig. 5). In this first initial phase, the target PS instance is created using the same configuration as the source PS.

Fig. 6B illustrates a second phase that includes reconfiguration of the target PS, including modification of RLC configuration for DAPS bearers (e.g., blocks 514, 530 of fig. 5), MAC reconfiguration (e.g., blocks 516, 532 of fig. 5). Here, the reconfiguration includes applying the target PS configuration parameters (RLC, MAC, phy) as increments over the first phase of fig. 6A.

FIG. 6C illustrates a third stage that includes reconfiguring PDCP of a DAPS bearer to PDCP-DAPS based on processing of radio bearer configuration of DAPS handover information from an RRC reconfiguration message.

As explained in the above example, when UE 110 receives the RRC reconfiguration message for the DAPS handoff (block 410), the target PS is instantiated based on the current source PS configuration (block 416 of fig. 4 and fig. 6A). The configuration of RLC, MAC and physical layers received in the RRC reconfiguration message is then applied to the target node 120b in the target PS instance. When the radio bearer configuration is processed after the above steps, the PDCP bearer is reconfigured for DAPS operation.

According to the restrictions indicated in the previous section, UE 110 is not allowed to transmit/receive with the secondary cell during the execution of the DAPS handoff. The network should release any secondary cells before issuing a DAPS HO command to UE 110. Furthermore, the RRC reconfiguration message containing the DAPS handoff information should also not configure the secondary cell for the target node 120 b. The SCell may be configured to UE 110 at block 432 of fig. 4 at the earliest. This limits the achievable data rates during DAPS handoff and introduces signaling overhead and delay due to the need to release scells and reconfigure them.

Delay and signaling overhead can occur because the network needs to first perform an RRC reconfiguration procedure to release the secondary cell before triggering the DAPS handoff command at block 410 of fig. 4. This additional signaling step results in signaling overhead for the DAPS handoff and also delays the execution of the DAPS handoff by the time consumed by this additional step.

The delay may be reduced by: the DAPS handover command is continuously transmitted after transmitting the RRC reconfiguration message (SCell release) without waiting for the SCell release procedure to complete. However, this may complicate processing at UE 110 and still require two separate signaling procedures to achieve the required state (i.e., no secondary cell when providing DAPS handoff information), resulting in tens of milliseconds of additional delay.

The decrease in throughput occurs because single cell operation in both the source node 120a and the target node 120b is limited at the start of the handover.

At least some examples of the present disclosure are directed to addressing these issues and maximizing the time that secondary cells are available when a DAPS handoff is required.

In at least some examples, the methods 700, 800, 900, 1000 of fig. 7-10 and/or portions thereof can be viewed as methods that delay secondary cell release to the time of execution of a DAPS handoff to enable longer time high throughput operation.

In at least some examples, the methods of fig. 7-10 and/or portions thereof can be viewed as methods that minimize the number of signaling procedures required to perform secondary cell release and DAPS handoff.

In at least some examples, the single DAPS handoff command message is adapted to include DAPS handoff information that also includes secondary cell release information. The secondary cell release information enables UE 110 to initiate a secondary cell release from the source PS at a defined trigger point during execution of the DAPS handoff. For example, the secondary cell release information may take the form of an instruction to release the secondary cell from the source PS.

In some examples, the secondary cell release information defines a trigger point. In other examples, the definition of the trigger point is predetermined (e.g., already stored in the UE memory before receiving the secondary cell release information).

Fig. 7-10 illustrate various methods for defining different definitions of trigger points and are now described.

Fig. 7-8 illustrate methods 700, 800, which methods 700, 800 include configuring UE behavior to process DAPS handoff commands to process secondary cell release information as a first phase prior to instantiation of a target PS (fig. 6A), i.e., when UE 110 begins performing a DAPS handoff.

As shown in method 800 of fig. 8 (which is a variant of fig. 5), this may be implemented as a new subframe 802 (checking for the presence of scells in DAPS handoff command and releasing scells at source PS), subframe 802 may be a subframe of block 512 of fig. 5, subframe 802 being processed prior to execution of one or more of blocks 522-528. Sub-box 802 serves as a definition trigger point.

By triggering release of the secondary cell from the source PS after receiving the DAPS handoff command but prior to instantiation of the target PS, the target PS with the secondary cell will not be created. With this modified behavior, when UE 110 instantiates the target PS, UE 110 will have the single cell operation required by both source node 120a and target node 120 b. Later, after the DAPS handoff is completed, the secondary cell may be added to the target PS.

Fig. 7 is a message sequence chart illustrating an example of a method 700. Method 700 illustrates an example of DAPS handoff feature operation similar to that of FIG. 4 that is configured to process a DAPS handoff command that also includes secondary cell release information such that the secondary cell is released from the source PS prior to instantiation of the target PS.

Alternatively, some blocks of fig. 7 may be unchanged relative to corresponding blocks in fig. 4, and are correspondingly given the same reference numerals. Different or new blocks are given new reference numerals compared to fig. 4.

Block 702 includes UE 110 transmitting a capability information message to source node 120a indicating whether UE 110 has the capability to receive secondary cell release information in a DAPS handoff command. In an example, UE 110 declares to the network that it is able to perform SCell release in a DAPS handoff command message.

Block 702 marks the message as "UE indicates SCell release ' capability ' in ' DAPS HO.

If UE 110 has this capability, then UE 110 supports reception of secondary cell release information in the DAPS handoff command, and in this case, UE 110 will defer single cell operation until after receiving the DAPS handoff command.

Some UEs may not have this capability. In this case, instead of performing the method 700 of fig. 7, the source node 120a may first send an RRC reconfiguration message (SCell release) and then send a DAPS handoff command.

Block 702 is shown as being performed before block 402 (measurement report), but may also be performed after block 402.

In an example, blocks 704-708 (404-408 variants) may be summarized as follows: a DAPS HO (DAPS handoff request message) is initiated by the source node 120a to the target node 120b to inform the target node 120b to prepare the DAPS HO command with SCell release (handoff request confirm message). A response (acknowledgement) is returned to the source node 120a, where the DAPS HO container (DAPS handoff configuration information) also contains the information elements needed by the UE 110 to handle SCell release.

Block 704 is a variation of block 404 ("handoff request") in which the DAPS handoff request message sent from the source node 120a to the target node 120b also considers capability information from the UE 110.

The DAPS handoff request message of block 704 also indicates whether the DAPS handoff information will include secondary cell release information. If so, execution of the requested DAPS handoff will include releasing the secondary cell from the source PS, e.g., according to sub-block 802 of FIG. 8.

In an example, the indication of whether secondary cell release information is to be included can be implemented as a new flag in the DAPS handoff request message, such that: if target node 120b accepts the request for DAPS handoff in the DAPS handoff request message, then the secondary cell release is included in the DAPS handoff command (to forward to UE 110 via source node 120 a).

Block 704 of fig. 7 marks the DAPS handoff request message as a handoff request (DAPS with SCell release).

Block 706 is the same as or similar to block 406 ("DAPS admission control") and may consider an indication as to whether the DAPS handoff information will include secondary cell release information.

Block 708 is a variation of block 408 ("handoff request confirm") in which the handoff request confirm message containing DAPS handoff configuration information further includes a secondary cell release information element.

Block 708 of fig. 7 marks the handoff request confirm message as "handoff request confirm (DAPS configuration with SCell release)".

Block 710 is a variation of block 410 ("RRC reconfiguration") in which the DAPS handoff command sent from source node 120a to UE 110 further includes secondary cell release information associated with the secondary cell release information element received from target node 120 b.

In an example, the secondary cell release information of block 710 is based on the secondary cell release information element of block 708. In an example, the secondary cell release information includes at least a portion of the secondary cell release information element of block 708. In an example, block 710 includes forwarding at least a portion of the secondary cell release information element received from the target node 120b to the UE 110 along with DAPS handoff information.

In an example implementation, the message of block 710 can include a DAPS handoff configuration information element with an extension to handle SCell release.

Block 710 of fig. 7 marks the single message as "RRC reconfiguration (DAPS configuration with SCell release)".

Blocks 412 and 414 ("user data" and "data forwarding") are shown.

Block 712 is a variation of block 416 ("DAPS operation") in which UE 110 initiates a DAPS handoff and as part of the cell group reconfiguration procedure (e.g., block 502 of fig. 5), UE 110 first processes secondary cell release information to release scells from the source PS prior to instantiating the target PS in the manner described previously. This will effectively downgrade the source PS from multi-cell CA operation to single-cell (i.e., PCell only) operation. In an example, the target SCell is not added until after the DAPS handoff is completed (e.g., at block 436).

The remaining operations 418-438 of fig. 4 (execution of the DAPS handoff) may remain substantially unchanged and are therefore not shown in fig. 7.

It is to be appreciated that the various blocks in fig. 7 may be omitted, altered, or reordered depending on the implementation of the standard or network, or depending on the use case.

Fig. 9A-10 illustrate different methods 900, 1000 for deferring processing of secondary cell release information during a DAPS handoff such that communication is not degraded from multi-cell CA operation to single-cell operation until a later trigger point (trigger condition).

A first example deferral trigger point includes an uplink handover. Another example deferred trigger point includes release of the source PS.

In an example, the deferral trigger point may be configurable by the network or a network administrator between different options. In an example, a network node (e.g., source node 120a and/or target node 120 b) is configured to determine a deferral trigger point.

In an example, determining the deferred trigger point includes determining which trigger point of a plurality of trigger points to use.

In other examples, determining the deferral trigger point includes looking up a preconfigured deferral trigger point.

In examples where the trigger point may be configurable between different options, the non-deferred trigger points of fig. 7-8 may be additional options.

Fig. 9A-9B show message sequence charts illustrating an example of method 900. Method 900 illustrates an example of DAPS handoff feature operation that differs from FIG. 7 such that release of the secondary cell is deferred to a deferred trigger point, later than instantiation of the target PS. Two options of deferring the trigger point (uplink handover or release of source PS) are shown.

Alternatively, some blocks of fig. 9A-9B may be unchanged relative to corresponding blocks in fig. 4 or 7, and are correspondingly given the same reference numerals. Different or new blocks are given new reference numerals compared to fig. 4 or fig. 7.

Blocks 702 and 402 (capability information and measurement report) are first shown.

Then, when it is determined that a DAPS handoff should be initiated, source node 120a can determine a trigger point, which in the example of FIGS. 9A-10 is a deferred trigger point. Source node 120a may decide which trigger point to use, at least one of the options being a deferred trigger point.

In an example, blocks 902-906 differ from blocks 704-708 due to deferred trigger points, and may be summarized as follows: a DAPS HO (DAPS handoff request message) is initiated by the source node to the target node 120b (902) to inform the target to prepare a DAPS HO command with SCell release with a specific trigger condition for SCell release (deferred trigger point). The trigger condition may be 1) at the UL handoff point during the execution of the DAPS handoff (new PDCP Service Data Units (SDUs) and PDCP Protocol Data Units (PDUs) not acknowledged by the source cell are sent to the target cell), or 2) during release of the source configuration at the release of the source PS. A response (906) is returned to the source node 120a, wherein the DAPS HO container (DAPS handoff configuration information) also contains the necessary information elements for the UE 110 to process SCell releases with trigger conditions.

The deferral trigger point itself may be proposed by source node 120a and accepted or modified by target node 120 b. In an example, the deferred trigger point may be determined by target node 120 b. However, since the modified behavior is related to the source PS, in a related example, control of the trigger point by the source node 120a is preferable.

Block 902 is a variation of block 704 ("handoff request"), wherein the DAPS handoff request message sent from the source node 120a to the target node 120b further includes trigger point information identifying the determined trigger point.

In an implementation, the deferred trigger point may form part of the flag sent from the source node 120a at block 902 in an RRC reconfiguration message (DAPS handoff request message) containing a command for a DAPS handoff. In an example, the target node 120b is not allowed to modify the flag (i.e., change the trigger point in time at which the release will occur).

Block 902 of fig. 9A marks the DAPS handoff request message as a handoff request (DAPS with SCell release with trigger).

Block 904 is the same or similar to block 706 ("DAPS admission control") and may also consider the trigger point indicated in the DAPS handoff request message.

Block 906 is a variation of block 708 ("handoff request confirm") in which the handoff request confirm message including the DAPS handoff configuration information and the secondary cell release information element further includes trigger point information that at least partially identifies a deferral trigger point. The deferred trigger point may be the same trigger point determined by source node 120a or may have been modified by target node 120 b.

Block 906 of fig. 9A marks the handoff request confirm message as "handoff request confirm (DAPS with SCell release with trigger)".

Block 908 is a variation of block 710 ("RRC reconfiguration") in which the DAPS handoff command sent from source node 120a to UE 110 further includes trigger point information that at least partially identifies a deferred trigger point received from target node 120b and/or determined by source node 120 a.

In an example, the trigger point information of block 908 is based on the trigger point information of block 906. In an example, the trigger point information of block 908 includes at least a portion of the trigger point information of block 906. In an example, block 908 comprises forwarding at least a portion of the trigger point information of block 906 received from the target node 120b to the UE 110 along with DAPS handoff information and secondary cell release information.

In an implementation, UE 110 receives a DAPS handoff configuration information element with an extension to handle secondary cell releases (with deferred trigger points) for storage for later use.

Block 908 of fig. 9A marks the RRC reconfiguration message as "RRC reconfiguration (DAPS with SCell release with trigger)".

Blocks 412 and 414 ("user data" and "data forwarding") are shown.

Blocks 910-916 are different from block 712 and involve storing a deferral trigger point and initiating performance of a DAPS handoff. Although blocks 910-916 are shown as separate blocks, they may be steps of a single process at UE 110.

Block 910 includes UE 110 causing storage of trigger point information indicating a deferred trigger point in volatile or non-volatile memory accessible to UE 110 and includes UE 110 initiating performance of a requested DAPS handoff. UE 110 continues to transmit to/receive from the secondary cell configured in the source PS in the user plane until the deferral trigger point given in the RRC message of block 908 is reached.

In some examples, if a trigger point is not provided to UE 110, a predetermined default trigger point may be processed. In some examples, the default trigger point includes random access completion (after blocks 422 or 424) and/or depending on the initiation of an uplink handover.

Block 910 of fig. 9A marks it as "store SCell release trigger condition and continues daps+ca at the source.

Block 912 includes instantiating the target PS. However, the secondary cell of the source PS has not been released yet. Thus, upon receiving the DAPS handoff command (RRC reconfiguration message), the target PS instantiated by the UE 110 will include the secondary cell (following the source configuration). In an example, the target PS instance is created by copying the content in the current source configuration. The replicated target PS will have secondary cells.

In an example, block 912 occurs when UE 110 is processing the "reconfiguration with sync" portion of the message (block 512 of fig. 5 and 10). See also fig. 6A. Block 912 in fig. 9A is written as "instantiate the target PS with CA".

Block 914 includes: after block 912, secondary cell release information of the target PS is processed. That is, UE 110 processes the secondary cell release portion of the received message and applies these changes (SCell release) only to the target PS instance. Thus, UE 110 releases the duplicate SCell from the target PS. Advantageously, UE 110 does not release SCell from source PS and is able to continue multi-cell CA with source node 120a until the deferral trigger point is reached. Block 914 of fig. 9A is written as "apply configured secondary cell release portion to target PS". Block 914 may occur substantially immediately after block 912.

Block 916 includes "target PS operation with primary cell only" while UE 110 continues with source PS operation with multi-cell configuration (primary and secondary cells).

Fig. 9B is a continuation of fig. 9A and shows an example of when different trigger points are met.

Blocks 418-424 are shown, which correspond to the performance of a DAPS handoff as described with respect to FIG. 4.

If the deferral trigger point comprises an uplink handover, block 918 releases the secondary cell from the source PS. The secondary cell may be released from the source PS at the uplink handover point.

The exact time of processing block 918 depends on the implementation. Block 918 may be processed prior to block 432 (source PS release) but after initiation of an uplink handover. Block 918 may be processed after the message is sent at block 424.

Block 918 of fig. 9B is written as "option 1: SCell(s) are released at the UL handoff point.

Blocks 426 through 432 are shown, which correspond to completion of a DAPS handoff as described with respect to FIG. 4. The message at block 432 is an RRC reconfiguration message (source PS release).

Block 920 is an alternative to block 434, which includes releasing the secondary cell at the same time as releasing the source PS if the deferred trigger point includes release of the source PS. In an example, the release of the source PS constitutes the release of the secondary cell. Up to this point, user plane communication with the secondary cell of the source PS continues, although a DAPS handoff is being performed.

The exact time of processing block 920 depends on the implementation. Block 920 may be processed prior to block 436 (UE 110 sends an RRC reconfiguration complete message to confirm release of the source PS) but after receiving the source PS release message at block 432.

Block 920 of fig. 9B is written as "option 2: SCell(s) +source configuration are released upon release of the source PS.

Method 1000 of FIG. 10 is a variation of FIG. 5 and illustrates how the deferred trigger points of FIGS. 9A-9B are implemented during processing of a DAPS handoff command by UE 110.

Fig. 10 includes additional blocks 1002-1014.

The new sub-block 1014 of block 512 ("reconfiguration with synchronization") includes applying the secondary cell release configuration (secondary cell release information) only to the target PS instance. In an example, block 1014 occurs after block 528.

Blocks 1002-1004 include: upon successful completion of RACH access to target node 120b by UE 110 (block 1002), the secondary cell is released from the source PS if the deferral trigger point is set to DAPS uplink handoff (block 1004).

Blocks 1006-1008 include: upon receipt of the source PS release message by UE 110 (block 1006), if the deferral trigger point is set to source PS release, then the source PS is released along with its secondary cell (block 1008).

Blocks 1010-1012 include: upon failure of the target RACH access (block 1010), UE 110 continues with the secondary cell without interruption (1012). This is an additional advantage of not releasing the secondary cell earlier.

The above-described method provides a number of advantages.

For the methods 700, 800 described with respect to FIGS. 7-8, CA operation can continue at the source PS until the UE 110 receives a DAPS handoff command. This represents a positive increase in user throughput, as the network does not have to plan to downgrade the source PS configuration to single PCell operation. Furthermore, the network saves the signaling overhead of two RRC reconfiguration procedures.

For the deferred trigger points described with respect to fig. 9A-10, CA operation may continue even further depending on UE capabilities.

If the trigger point is deferred to an uplink handoff, CA operation at the source node continues until UE 110 reaches the UL handoff point of the DAPS, i.e., when random access is successfully completed. This results in an increase in user data throughput compared to the methods of fig. 7-8.

CA operation may further continue to source PS release, depending on UE capabilities. In this case, CA operation at source node 120a continues until UE 110 receives a source PS release, indicating that UE 110 continues with a source PS of CA and a target PS with a single PCell. This results in an increase in user data throughput compared to the two trigger points described above (instant or uplink handover).

The features described in the foregoing description may be used in other combinations than those explicitly described. For example, as described previously, in addition to option 1 (uplink handover) or option 2 (source PS release), as a third option, the implementation of the methods 700, 800 of fig. 7-8 may be performed by the methods 900, 1000 of fig. 9A-10 by defining the trigger point for releasing the secondary cell as receipt of an RRC reconfiguration containing a DAPS handover command.

Fig. 11 shows an example of a controller 1600. The controller 1600 may be implemented as controller circuitry. The controller 1600 may be implemented in hardware alone, with certain aspects in software including firmware alone, or may be a combination of hardware and software (including firmware).

As shown in fig. 11, the controller 1600 may be implemented using hardware function-enabled instructions, for example, by using executable instructions of a computer program 1606 in a general-purpose or special-purpose processor 1602, which may be stored on a computer-readable storage medium (disk, memory, etc.) for execution by such processor 1602.

The processor 1602 is configured to read from the memory 1604 and write to the memory 1604. The processor 1602 may also include an output interface via which the processor 1602 outputs data and/or commands, and an input interface via which data and/or commands are input to the processor 1602.

The memory 1604 stores a computer program 1606 comprising computer program instructions (computer program code) that, when loaded into the processor 1602, control the operation of the apparatus 110, 120. The computer program instructions of the computer program 1606 provide logic and routines that enables a computer (such as the apparatus) to perform the methods illustrated in fig. 4-10. The processor 1602, by reading the memory 1604, is able to load and execute the computer program 1606.

Accordingly, the means used by the apparatus 110, 120 to perform the method(s) described herein may include:

at least one processor 1602; and

at least one memory 1604 including computer program code,

from the perspective of the UE 110, the source node 120a, the target node 120b, or the entire network 100, the at least one memory 1604 and the computer program code are configured to, with the at least one processor 1602, cause the apparatus 110, 120 to perform at least any one or more of the methods described herein.

As shown in fig. 12, the computer program 1606 may reach the devices 110, 120 via any suitable delivery mechanism 1700. Delivery mechanism 1700 may be, for example, a machine-readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a recording medium such as a compact disk read only memory (CD-ROM) or Digital Versatile Disk (DVD) or solid state memory, an article of manufacture that includes or tangibly embodies computer program 1606. The delivery mechanism may be a signal configured to reliably transfer the computer program 1606. The apparatus 110, 120 may propagate or transmit the computer program 1606 as a computer data signal.

Computer program instructions for causing an apparatus to perform or for performing at least the following:

from the perspective of UE 110, source node 120a, target node 120b, or the entire network 100, cause performance of any one or more of the methods described herein.

The computer program instructions may be included in a computer program, a non-transitory computer readable medium, a computer program product, a machine readable medium. In some, but not necessarily all, examples, the computer program instructions may be distributed over more than one computer program.

Although the memory 1604 is shown as a single component/circuitry, it may be implemented as one or more separate components/circuitry, some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/dynamic/cached storage.

Although the processor 1602 is shown as a single component/circuitry, it may be implemented as one or more separate components/circuitry, some or all of which may be integrated/removable. Processor 1602 may be a single-core or multi-core processor.

References to "computer-readable storage medium", "computer program product", "tangibly embodied computer program", etc., or "controller", "computer", "processor", etc., should be understood to include not only computers having different architectures such as single/multiprocessor architectures and sequential (von neumann)/parallel architectures, but also special-purpose circuits such as field-programmable gate arrays (FPGA), application-specific circuits (ASIC), signal processing devices, and other processing circuitry. References to computer programs, instructions, code etc. should be understood to encompass software of a programmable processor or firmware, such as the programmable content of a hardware device, whether instructions of a processor, or configuration settings of a fixed-function device, gate array or programmable logic device etc.

As used in this application, the term "circuitry" may refer to one or more or all of the following:

(a) Pure hardware circuitry implementations (such as implementations in analog and/or digital circuitry only), and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combination of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Any portion of the hardware processor(s), including digital signal processor(s), software, and memory(s) with software that work together to cause a device, such as a mobile phone or server, to perform various functions, and

(c) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or portion of microprocessor(s), that require software (e.g., firmware) to operate, but software may not be present when operation is not required.

The definition of circuitry applies to all uses of this term in this application, including in any claims. As another example, as used in this application, the term circuitry also encompasses an implementation of only a hardware circuit or processor and its accompanying software and/or firmware. For example, if applicable to the particular claim element, the term circuitry also encompasses a baseband integrated circuit or server for a mobile device, a cellular network device, or a similar integrated circuit in other computing or network devices.

The blocks illustrated in fig. 4-10 may represent steps in a method and/or code segments in the computer program 1606. The illustration of a particular order of the blocks does not necessarily indicate a required or preferred order for the blocks to exist, and the order and arrangement of the blocks may be altered. In addition, some blocks may be omitted.

Where a structural feature is described, the structural feature may be replaced with a means for performing one or more functions of the structural feature, whether the function or functions are explicitly described or implicitly described.

The above example will apply as an enabling component for:

an automotive system; a telecommunications system; electronic systems, including consumer electronics; a distributed computing system; media systems for generating or rendering media content, including audio, visual and audiovisual content, as well as mixed, intermediate, virtual and/or augmented reality; personal systems, including personal wellness systems or personal fitness systems; a navigation system; user interfaces, also known as human-machine interfaces; networks including cellular networks, non-cellular networks, and optical networks; an ad hoc network; the Internet; the Internet of things; virtualizing a network; related software and services.

The term "comprising" as used in this document is inclusive and not exclusive. That is, any reference to X including Y means that X may include only one Y or may include a plurality of Y. If an exclusive meaning of "comprising" is intended to be used, it will be explicitly stated in the context by reference to "comprising only one (comprising only one)" or the use of "consisting of … …".

In this specification, various examples are referred to. The description of features or functions in connection with an example indicates that the features or functions are present in the example. The use of the term "example" or "e.g." or "possible" or "may" in this text indicates that such feature or function, whether explicitly stated or not, is present in at least the described examples, whether or not described as examples, and that they may, but need not, be present in some or all other examples. Thus, "example" or "e.g." or "possible" or "may" refer to a particular instance in a class of examples. The attributes of an instance may be attributes of only that instance or attributes of a class or attributes of a subclass of a class that includes some but not all instances. Thus, it is implicitly disclosed that features described with reference to one example but not with reference to another example may be used in that other example as part of a combination of operations where possible, but are not necessarily used in that other example.

Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

Although functions have been described with reference to certain features, these functions may be performed by other features, whether described or not.

Although features have been described with reference to certain examples, these features may also be present in other examples, whether described or not.

The terms "a" or "an" as used in this document are intended to be inclusive rather than exclusive. That is, any reference to X including one (a)/the (the) Y means that X may include only one Y or may include a plurality of Y unless the context clearly indicates to the contrary. If "a" or "the" is intended to be used in an exclusive sense, it will be apparent from the context. In some instances, the use of "at least one" or "one or more" may be employed to emphasize an inclusive meaning, but the absence of such terms should not be construed as an inference of any exclusive meaning.

The presence of a feature (or combination of features) in the claims is a reference to that feature or (combination of features) itself, as well as to features (equivalent features) that achieve substantially the same technical result. Equivalent features include, for example, features that are variants and that achieve substantially the same result in substantially the same way. Equivalent features include, for example, features that perform substantially the same function in substantially the same way to achieve substantially the same result.

In this specification, various examples are referenced, and adjectives or adjective phrases are used to describe features of the examples. Such description of the characteristics associated with the examples indicates that the characteristics exist, in some examples, entirely as described and, in other examples, substantially as described.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. An apparatus comprising means for:

receiving reconfiguration information for user equipment to perform, wherein the reconfiguration information comprises dual-active protocol stack, DAPS, handover information, wherein the DAPS handover information comprises secondary cell release information; and

initiating a DAPS handoff based on receiving the DAPS handoff information with the secondary cell release information, the DAPS handoff comprising: released from the secondary cell of the source protocol stack at a defined trigger point during execution of the DAPS handoff.

2. The apparatus of claim 1, wherein the reconfiguration information comprises a reconfiguration message comprising: the DAPS handoff information with the secondary cell release information.

3. The apparatus of claim 1 or 2, comprising means for transmitting capability information to a network node, the capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the received reconfiguration information depending on the user equipment having the capability.

4. The apparatus of claim 1, 2, or 3, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

5. The apparatus of claim 4, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

6. The apparatus of any preceding claim, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

7. The apparatus of claim 6, wherein the defined trigger point comprises a default trigger point if the secondary cell release information does not include the trigger point information that at least partially identifies the defined trigger point.

8. The apparatus of claim 7, wherein the default trigger point comprises random access completion and/or is dependent on initiation of an uplink handover.

9. An apparatus as claimed in any preceding claim, wherein the apparatus is a user equipment apparatus for controlling the user equipment.

10. An apparatus comprising means for:

transmitting reconfiguration information for execution by a user equipment, wherein the reconfiguration information comprises dual active protocol stack, DAPS, handoff information, wherein the DAPS handoff information comprises secondary cell release information to enable: based on receiving the DAPS handoff information at the user equipment, secondary cell release from a source protocol stack is initiated at a defined trigger point during execution of the DAPS handoff.

11. The apparatus of claim 10, comprising means for receiving capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the reconfiguration information that is transmitted depending on the user equipment having the capability.

12. The apparatus of claim 10 or 11, comprising means for sending a DAPS handoff request to a target node, the DAPS handoff request comprising a flag indicating whether the DAPS handoff information comprises the secondary cell release information.

13. The apparatus of claim 12, comprising means for receiving a handoff request acknowledgement in response to the DAPS handoff request, the handoff request acknowledgement comprising DAPS handoff configuration information with a secondary cell release information element.

14. The apparatus of claim 13, comprising means for operating as a source node that provides radio resources to the user equipment with carrier aggregation via a set of serving cells including a primary cell and one or more secondary cells, and continues the operation with carrier aggregation as a source node with the primary cell and the one or more secondary cells after receiving the handoff request acknowledgement and until the secondary cell release is performed during the performance of the DAPS handoff.

15. The apparatus of any of claims 10 to 14, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

16. The apparatus of claim 15, comprising means for determining the defined trigger point that controls when to initiate the secondary cell release during performance of the DAPS handoff, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

17. The apparatus of claim 16, wherein determining the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.

18. The apparatus of claim 15, 16 or 17, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

19. The apparatus of any of claims 10 to 18, wherein the apparatus is a network node apparatus comprising means for operating as a source node prior to completion of execution of the DAPS handoff.

20. An apparatus comprising means for:

in response, a handoff request acknowledgement is sent that includes DAPS handoff configuration information having a secondary cell release information element for release from a secondary cell of a source protocol stack at a defined trigger point during execution of a DAPS handoff based on the DAPS handoff configuration information.

21. The apparatus of claim 20, wherein the DAPS handoff request comprises a flag indicating whether reconfiguration information to be sent for execution by the user equipment based on the handoff request acknowledgement should include secondary cell release information, and wherein the secondary cell release information element depends on the flag.

22. The apparatus of claim 20 or 21, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to be reached after instantiation of the target protocol stack during execution of the DAPS handoff.

23. The apparatus of claim 22, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

24. The apparatus of claim 23, comprising means for sending reconfiguration information to the user equipment, the reconfiguration information comprising the initiated source protocol stack release information for causing, at least in part, release of the source protocol stack.

25. The apparatus of any of claims 20-24, comprising means for determining or modifying the defined trigger point that controls when the secondary cell release is initiated during execution of the DAPS handoff, wherein the handoff request acknowledgement comprises trigger point information that at least partially identifies the determined or modified defined trigger point.

26. The apparatus of claim 25, wherein determining or modifying the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.

27. The apparatus of any of claims 10 to 26, wherein the apparatus is a network node apparatus comprising means for operating as a target node prior to completion of performance of the DAPS handoff.

28. A network comprising a source node according to claim 19 and a target node according to claim 27.

29. The apparatus of any one of the preceding claims, wherein the means comprises at least one processor; and at least one memory including computer program code.

30. A method, comprising:

31. The method of claim 30, wherein the reconfiguration information comprises a reconfiguration message that includes the DAPS handoff information with the secondary cell release information.

32. The method of claim 30 or 31, comprising sending capability information to a network node, the capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the received reconfiguration information depending on whether the user equipment has the capability.

33. The method of claim 30, 31 or 32, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

34. The method of claim 33, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

35. The method of any of claims 30 to 34, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

36. The method of claim 35, wherein the defined trigger point comprises a default trigger point if the secondary cell release information does not include the trigger point information that at least partially identifies the defined trigger point.

37. The method of claim 36, wherein the default trigger point comprises random access completion and/or is dependent on initiation of an uplink handover.

38. A method, comprising:

39. The method of claim 38, comprising receiving capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the reconfiguration information sent depending on the user equipment having the capability.

40. The method of claim 38 or 39 comprising sending a DAPS handoff request to a target node, the DAPS handoff request comprising a flag indicating whether the DAPS handoff information comprises the secondary cell release information.

41. The method of claim 40 comprising receiving a handoff request acknowledgement in response to the DAPS handoff request, the handoff request acknowledgement comprising DAPS handoff configuration information with a secondary cell release information element.

42. The method of claim 41, comprising operating as a source node that provides radio resources to the user equipment with carrier aggregation via a set of serving cells including a primary cell and one or more secondary cells, and continuing the operation as a source node with carrier aggregation having the primary cell and the one or more secondary cells after receiving the handoff request acknowledgement and until the secondary cell release is performed during the performance of the DAPS handoff.

43. The method of any one of claims 38 to 42, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

44. The method of claim 43, comprising determining the defined trigger point that controls when to initiate the secondary cell release during performance of the DAPS handoff, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

45. The method of claim 44, wherein determining the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.

46. The method of claim 43, 44 or 45, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

47. A method, comprising:

48. The method of claim 47 wherein the DAPS handoff request comprises a flag indicating whether reconfiguration information to be sent for execution by the user equipment based on the handoff request acknowledgement should include secondary cell release information, and wherein the secondary cell release information element depends on the flag.

49. The method of claim 47 or 48, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to be reached after instantiation of the target protocol stack during execution of the DAPS handoff.

50. The method of claim 49, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

51. The method of claim 50, comprising sending reconfiguration information to the user equipment, the reconfiguration information comprising the initiated source protocol stack release information for causing, at least in part, release of the source protocol stack.

52. The method of any of claims 47-51, comprising determining or modifying the defined trigger point that controls when the secondary cell release is initiated during performance of the DAPS handoff, wherein the handoff request acknowledgement includes trigger point information that at least partially identifies the determined or modified defined trigger point.

53. The method of claim 52, wherein determining or modifying the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.

54. A computer program which, when run by a computer, causes:

55. The computer program of claim 54, wherein the reconfiguration information comprises a reconfiguration message that includes the DAPS handoff information with the secondary cell release information.

56. The computer program of claim 54 or 55, which when executed by the computer causes sending capability information to a network node, the capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the received reconfiguration information depending on whether the user equipment has the capability.

57. The computer program of claim 54, 55, or 56, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to be reached after instantiation of the target protocol stack during execution of the DAPS handoff.

58. The computer program of claim 57, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

59. A computer program as claimed in any of claims 54 to 58, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

60. The computer program of claim 59, wherein the defined trigger point comprises a default trigger point if the secondary cell release information does not include the trigger point information that at least partially identifies the defined trigger point.

61. The computer program of claim 60, wherein the default trigger point comprises random access completion and/or is dependent on initiation of an uplink handover.

62. A computer program which, when run by a computer, causes:

63. The computer program of claim 62, which when executed by a computer causes receiving capability information indicating whether the user equipment has the capability to receive the DAPS handoff information with the secondary cell release information, wherein the secondary cell release information is included in the reconfiguration information sent depending on the user equipment having the capability.

64. The computer program of claim 62 or 63 which, when executed by a computer, causes a DAPS handoff request to be sent to a target node, the DAPS handoff request comprising a flag indicating whether the DAPS handoff information comprises the secondary cell release information.

65. The computer program of claim 64, which when executed by a computer causes: a handoff request acknowledgement is received in response to the DAPS handoff request, the handoff request acknowledgement including DAPS handoff configuration information with a secondary cell release information element.

66. The computer program of claim 65, which when executed by a computer causes: the method further includes operating as a source node that provides radio resources to the user equipment with carrier aggregation via a set of serving cells including a primary cell and one or more secondary cells, and continuing the operating as a source node with carrier aggregation having the primary cell and the one or more secondary cells after receiving the handoff request acknowledgement and until the secondary cell release is performed during the performance of the DAPS handoff.

67. The computer program of any one of claims 62 to 66, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

68. The computer program of claim 67, which when executed by a computer causes determining the defined trigger point that controls when the secondary cell release is initiated during execution of the DAPS handoff, wherein the secondary cell release information comprises trigger point information that at least partially identifies the defined trigger point.

69. The computer program of claim 68, wherein determining the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.

70. The computer program of claim 67, 68, or 69, wherein the deferral trigger point is dependent on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

71. A computer program which, when run by a computer, causes:

72. The computer program of claim 71, wherein the DAPS handoff request comprises a flag indicating whether reconfiguration information to be sent for execution by the user equipment based on the handoff request acknowledgement should include secondary cell release information, and wherein the secondary cell release information element depends on the flag.

73. The computer program of claim 71 or 72, wherein the defined trigger point is configured to: is reached prior to instantiation of a target protocol stack during execution of the DAPS handoff, or wherein the defined trigger point is a deferral trigger point configured to: is reached after instantiation of the target protocol stack during execution of the DAPS handoff.

74. The computer program of claim 73, wherein the deferral trigger point depends on: 1) Initiation of an uplink handover; or 2) initiation of a release of the source protocol stack.

75. The computer program of claim 74, which when executed by a computer causes sending reconfiguration information to the user equipment, the reconfiguration information comprising the initiated source protocol stack release information for causing, at least in part, release of the source protocol stack.

76. The computer program of any of claims 71 to 75, when executed by a computer, causes determining or modifying the defined trigger point that controls when the secondary cell release is initiated during execution of the DAPS handoff, wherein the handoff request acknowledgement comprises trigger point information that at least partially identifies the determined or modified defined trigger point.

77. The computer program of claim 76, wherein determining or modifying the defined trigger point comprises: determining which trigger point of a plurality of trigger points is to be indicated by the trigger point information.