EP4193667A1

EP4193667A1 - Conditional handover

Info

Publication number: EP4193667A1
Application number: EP21748881.6A
Authority: EP
Inventors: Srinivasan Selvaganapathy; Amaanat ALI; Ahmad AWADA; Tero Henttonen
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2020-08-05
Filing date: 2021-07-23
Publication date: 2023-06-14
Also published as: WO2022028918A1

Abstract

An apparatus comprising means for: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

Description

TITLE

CONDITIONAL HANDOVER

TECHNOLOGICAL FIELD

Embodiments of the present disclosure relate to conditional handover. Some relate to conditional handover with dual connectivity configuration.

BACKGROUND

A wireless network comprises a plurality of network nodes including terminal nodes and access nodes. Communication between the terminal nodes and access nodes is wireless.

In some circumstances it may be desirable to enable conditional handover with a target dual connectivity configuration.

BRIEF SUMMARY

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

According to various, but not necessarily all, embodiments there is provided an apparatus comprising means for: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity. In examples, the means are configured to, if it is determined at a later time that the addition condition for the primary secondary cell is satisfied, enable completion of conditional addition of the primary secondary cell for dual connectivity.

In examples, enabling the completion of conditional handover and the completion of the conditional addition comprises establishing an active radio link.

In examples, the completion of conditional handover to the primary cell is enabled, without enabling the completion of conditional addition to the primary secondary cell for dual connectivity, after a timeout period has expired after the handover execution condition for the primary cell is satisfied.

In examples, the means are configured to receive the timeout period value.

In examples, the means are configured to cause transmission, to a network node, of information configured to provide an indication of the primary secondary cell conditional addition status.

In examples, the indication of the primary secondary cell conditional addition status comprises at least one of: an indication that the addition condition for the primary secondary cell is not yet satisfied; an indication that an active radio link with the primary secondary cell is not yet established; and where a timeout period is used, a value of a timeout period timer.

In examples, the handover execution condition for the primary cell is A3 condition and/or the addition condition for the primary secondary cell is A4 condition.

In examples, the means are configured to cause transmission of information indicative of one or more measurement results of the primary secondary cell.

In examples the configuration information comprises: configuration information for handover to the primary cell; and configuration information for enabling the delayed dual connectivity with the primary secondary cell. In examples, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

According to various, but not necessarily all, embodiments there is provided a method comprising: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

In examples, the method comprises, if it is determined at a later time that the addition condition for the primary secondary cell is satisfied, enabling completion of conditional addition of the primary secondary cell for dual connectivity.

In examples, enabling the completion of conditional handover and the completion of conditional addition comprises establishing an active radio link.

In examples, the method comprises receiving the timeout period value.

In examples, the method comprises causing transmission, to a network node, of information configured to provide an indication of the primary secondary cell conditional addition status. In examples, the indication of the primary secondary cell conditional addition status comprises at least one of: an indication that the addition condition for the primary secondary cell is not yet satisfied; an indication that an active radio link with the primary secondary cell is not yet established; and where a timeout period is used, a value of a timeout period timer.

In examples, the method comprises causing transmission of information indicative of one or more measurement results of the primary secondary cell.

In examples, the configuration information comprises: configuration information for handover to the primary cell; and configuration information for enabling the delayed dual connectivity with the primary secondary cell.

According to various, but not necessarily all, embodiments there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

According to various, but not necessarily all, embodiments there is provided a computer program comprising instructions for causing an apparatus to perform at least a part of one or more methods as disclosed herein. According to various, but not necessarily all, embodiments there is provided an apparatus comprising means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: causing transmission of configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

In examples, the means are configured to enable the completion of conditional handover to the primary cell without dual connectivity to the primary secondary cell and enable initiation, but not completion, of addition with dual connectivity to the primary secondary cell.

In examples, enabling the completion of conditional handover to the primary cell and/or enabling the delay of addition of the primary secondary cell for dual connectivity comprises remapping bearers.

In examples, the means are configured to inform a target secondary node that the UE is not yet available.

In examples, the configuration information comprises a timeout period value.

In examples, the means comprises at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

According to various, but not necessarily all, embodiments there is provided a method comprising: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: causing transmission of configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition to the primary secondary cell for dual connectivity.

In examples, the method comprises enabling the completion of conditional handover to the primary cell without dual connectivity to the primary secondary cell and enable initiation, but not completion, of addition with dual connectivity to the primary secondary cell.

In examples, the method comprises informing a target secondary node that the UE is not yet available.

According to various, but not necessarily all, embodiments there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: transmitting configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition to of the primary secondary cell for dual connectivity.

According to various, but not necessarily all, embodiments there is provided an apparatus comprising means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.

In examples, the means are configured to subsequently enable completion of addition of the primary secondary cell for dual connectivity.

In examples, the means are configured to inform a master node that addition of the primary secondary cell for dual connectivity has been completed.

According to various, but not necessarily all, embodiments there is provided a method comprising: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied. According to various, but not necessarily all, embodiments there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.

The description of a function and/or action should additionally be considered to also disclose any means suitable for performing that function and/or action.

BRIEF DESCRIPTION

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

FIG. 1 shows an example of the subject matter described herein;

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

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

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

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

FIG. 6 shows another example of the subject matter described herein;

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

FIG. 8A shows another example of the subject matter described herein; and

FIG. 8B shows another example of the subject matter described herein.

DEFINITIONS

Master Node (MN): Network node that provides control plane connectivity towards the core network.

Master Cell Group (MCG): Group of cells associated with the MN, includes PCell.

Secondary Node (SN): Network node that is providing additional radio resources for the UE but is not the MN. Secondary Cell Group (SCG): Group of cells associated with the SN, includes PSCell.

PCell: the cell for uplink/downlink connection to MN. Cell of MCG used to initiate initial access to the MN.

PSCell: the cell for uplink/downlink connection to SN. Cell of SCG used to initiate initial access to the SN.

Conditional Handover (CHO) - a handover procedure that is triggered by the UE only when the configured execution condition(s) are met for a candidate cell. Condition(s) preconfigured by network. In 3GPP, a conditional handover execution condition is specified by condExecutionCond within the CondReconfigToAddModList information element within the ConditionalReconfiguration information element within an RRCReconfiguration message.

Dual Connectivity (DC):

UE has contemporaneous connection to an MN and an SN. This is a mode of operation of a UE in RRC_CONNECTED, configured with a Master Cell Group and a Secondary Cell Group.

Configuration Information:

Information used to configure operation of a UE. In 3GPP, the configuration information can, for example, be provided in an RRCReconfiguration message.

The term “configuration information comprising” and entity (for example handover execution condition for a primary cell; addition condition for dual connectivity with the primary cell and so on) can mean that the configuration information comprises information sufficient to obtain the entity. It may or may not comprise all parameters of the entity, it may instead comprise pointer to the entity or parameters of the entity or can mean that configuration includes the entity.

Conditional handover (CHO) configuration information

Configuration information for handover to a primary cell. The CHO configuration information can comprise a handover execution condition for a primary cell and a measurement configuration for configuring measurements for a handover execution condition for the primary cell. Triggering conditional handover to the primary cell is dependent upon the measurements meeting the handover execution condition for the primary cell.

In 3GPP, a RRCReconfiguration message specifies a ConditionalReconfiguration information element which provides the CHO configuration. The ConditionalReconfiguration information element comprises a CondReconfigToAddModList information element. The CondReconfigToAddModList information element comprises condExecutionCond and condRRCReconfig. Handover execution condition(s) for a primary cell are specified by condExecutionCond. The RRCReconfiguration message to be applied when the specified conditions are met is provided by condRRCReconfig.

Dual Connectivity (DC) configuration information

Configuration information for dual connectivity to a primary secondary cell (PSCell). The DC configuration information can comprise an addition condition for a primary secondary cell for dual connectivity with the primary cell and a measurement configuration for configuring measurements for an addition condition for the primary secondary cell for dual connectivity with the primary cell, that is, dual connectivity of the UE with both the primary cell and the primary secondary cell.

Triggering addition of a primary secondary cell for dual connectivity is dependent upon the measurements meeting the addition condition for the primary secondary cell.

In 3GPP, a RRCReconfiguration message specifies a ConditionalReconfiguration information element which provides addition conditions for the DC. The ConditionalReconfiguration information element comprises a CondReconfigToAddModList information element. The CondReconfigToAddModList information element comprises condExecutionCond and condRRCReconfig. Addition condition(s) for a primary secondary cell (PSCell) are specified by condExecutionCond. The RRCReconfiguration message to be applied when the specified conditions are met is provided by condRRCReconfig.

DETAILED DESCRIPTION

FIG 1 illustrates an example of a network 100 comprising a plurality of network nodes including terminal nodes 110, access nodes 120 and one or more core nodes 129. The terminal nodes 110 and access nodes 120 communicate with each other. The one or more core nodes 129 communicate with the access nodes 120.

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

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

The network 100 may be a cellular network comprising a plurality of cells 122 each served by an access node 120. In this example, the interface between the terminal nodes 110 and an access node 120 defining a cell 122 is a wireless interface 124.

The access node 120 is a cellular radio transceiver. The terminal nodes 110 are cellular radio transceivers.

In the example illustrated the cellular network 100 is a third generation Partnership Project (3GPP) network in which the terminal nodes 110 are user equipment (UE 204, see, for example, FIG. 2) and the access nodes 120 are base stations.

In the particular example illustrated the network 100 is an Evolved Universal Terrestrial Radio Access network (E-UTRAN). The E-UTRAN consists of E-UTRAN NodeBs (eNBs) 120, providing the E-UTRA user plane and control plane (for example, RRC) protocol terminations towards the UE 204. The eNBs 120 are interconnected with each other by means of an X2 interface 126. The eNBs are also connected by means of the S1 interface 128 to the Mobility Management Entity (MME) 129.

In other example the network 100 is a Next Generation (or New Radio, NR) Radio Access network (NG-RAN). The NG-RAN consists of gNodeBs (gNBs) 120, providing the user plane and control plane (for example, RRC) protocol terminations towards the UE 204. The gNBs 120 are interconnected with each other by means of an X2/Xn interface 126. The gNBs are also connected by means of the N2 interface 128 to the Access and Mobility management Function (AMF).

In examples, the network 100 can comprise a combination of E-UTRAN and NG-RAN. A UE 204 can perform a handover procedure to change the serving cell of the UE 204. In examples, a handover procedure can be a conditional handover procedure.

A conditional handover (CHO) procedure can be considered a handover that is triggered by the UE 204 when one or more handover execution conditions 208 (see, for example, FIG.

2) are met. The handover execution condition or conditions 208 can be pre-configured by the network 100.

In examples, the UE 204 starts evaluating the execution condition(s) 208 for CHO candidate cells upon receiving a CHO configuration, and executes the handover command once the execution condition(s) 208 are met for a CHO candidate cell. The UE 204 may stop evaluating the execution condition(s) 208 for other candidate cells once the execution condition(s) 208 are met for a candidate cell.

In 3GPP, a RRCReconfiguration message specifies a ConditionalREconfiguration information element which provides the CHO configuration. The ConditionalReconfiguration information element comprises a CondReconfigToAddModList information element. The CondReconfigToAddModList information element comprises condExecutionCond and condRRCReconfig. Handover execution condition(s) 208 for a primary cell are specified by condExecutionCond. The RRCReconfiguration message to be applied when the specified conditions are met is provided by condRRCReconfig.

In examples, a UE 204 can be provided with additional radio resources using dual connectivity (DC).

In DC, the configured set of serving cells for a UE 204 has two subsets: the Master Cell Group (MCG) containing the serving cells of a Master Node (MN) 216, and the Secondary Cell Group (SCG) containing the serving cells of a Secondary Node (SN) 218.

In examples, the MN 216 can be considered to be a network node that provides control plane connectivity towards the core network and the SN 218 can be considered to be a network node that is providing additional radio resources for the UE 204 but is not the MN 216. The MCG comprises a Primary Cell (PCell) for uplink/downlink connection to the MN 216. In examples, the PCell is the cell of the MCG used to initiate initial access to the MN 216 by the UE 204, for example using a random access procedure.

Similarly, the SCG comprises a Primary Secondary Cell (PSCell) for uplink/downlink connection to the SN 218. In examples, the PSCell is the cell of the SCG used to initiate initial access to the SN by the UE, for example using a random access procedure. The PSCell can be configured with Physical Uplink Control Channel (PUCCH) resources.

In 3GPP, a RRCReconfiguration message specifies, for the MCG, a MCG configuration via CellGroupConfig and a measurement configuration via measConfig and specifies, for each SCG, a SCG configuration via CellGroupConfig and a measurement configuration via measConfig.

The RRCReconfiguration message can also provide a ConditionalReconfiguration information element which provides addition conditions 210 for the DC. The ConditionalReconfiguration information element comprises a CondReconfigToAddModList information element. The CondReconfigToAddModList information element comprises condExecutionCond and condRRCReconfig. Addition condition(s) 210 for a primary secondary cell (PSCell) are specified by condExecutionCond. The RRCREconfiguration message to be applied when the specified conditions are met is provided by condRRCReconfig.

It is desirable to enable a conditional handover with dual connectivity. A conditional handover with dual connectivity changes the MN 216 (and optionally the SN 218) of a DC configuration. Such a handover is an inter-MN handover.

During DC, SN terminated SCG bearers terminate in the SN 218 and MN terminated SCG bearers terminate in the MN 216. They are end to end tunnels terminating at the Packet Data Convergence Protocol (PDCP) layer. In examples, an SCG Bearer can be a user plane bearer with the PDCP either at the MN 216 or the SN 218 but will use the Radio Link Control (RLC), Medium Access Control (MAC) and Physical layers within the SN 218.

MN terminated MCG bearers terminate in MN 216 and SN terminated MCG bearers terminate in the SN 218. They are end to end tunnels terminating at the Packet Data Convergence Protocol (PDCP) layer. In examples, an MCG Bearer can be a user plane bearer with the PDCP either at the MN 216 or the SN 218 but will use the Radio Link Control (RLC), Medium Access Control (MAC) and Physical layers within the MN 216.

In examples, a traffic stream can be remapped from an SCG to an MCG bearer (and vice versa) using RRCReconfiguration.

As bearers are at a higher layer than the physical layer (layer 1) they can be prepared independently to the physical layer connection or lower sub-layer (for example Radio Link Control (RLC) or Medium Access Control (MAC)) connection.

A physical layer connection between a UE 204 and a network node can be suspended. In a suspended state a UE 204 and the network are configured to maintain resources at higher layers so that, for example, a user plane connection can be quickly resumed when the physical layer connection resumes. In a suspended state, the mapping of the bearers may be maintained in anticipation of a resumption of the physical connection.

From the UE 204 perspective, the completion of conditional handover with dual connectivity, requires a completion of conditional handover to a new primary cell (for example, Target MN 216b) and a completion of addition of a primary secondary cell for dual connectivity (for example, Target SN 218).

From the UE 204 perspective, the completion of conditional handover with dual connectivity, requires a completion of conditional handover to a new serving MN 216b (i.e., the target MN 216b) and a completion of addition of a SN 218 for dual connectivity.

In some examples, when performing conditional handover with dual connectivity, the completion of conditional handover to the primary cell/MN 216 is contemporaneous with a completion of addition of a primary secondary cell/SN 218.

In some examples, when performing conditional handover with dual connectivity, the initiation, for example, triggering/execution of conditional handover to the primary cell/MN 216 is contemporaneous with a completion of addition of a primary secondary cell/SN 218.

In some examples, when performing conditional handover with dual connectivity, the completion of conditional handover to the primary cell/MN 216 occurs before the completion of addition of a primary secondary cell/SN 218. The completion of addition of a primary secondary cell/SN 218 is delayed. This can be described as delayed access.

In some examples, when performing conditional handover with dual connectivity, the initiation, for example, triggering/execution of conditional handover to the primary cell/MN 216 occurs before the initiation, for example, triggering/execution of addition of a primary secondary cell/SN 218. The initiation of addition of a primary secondary cell/SN 218 is delayed. This can be described as delayed access.

The completion of conditional handover to the primary cell/MN 216b can, for example, result in direct access of the UE 204 to a new MN 216b; establishment of a radio link between the UE 204 and the MN/MCG that enables the transfer of data via uplink (UL) and/or downlink (DL). The radio link can, for example, be established by initiating a RACH procedure at the UE 204; traffic flow via bearer between the UE 204 and the network via the MN/MCG;

The completion of addition of the primary secondary cell/SN 218 can, for example, result in direct access of the UE 204 to a new SN 218; establishment of a radio link between the UE 204 and the SN/SCG that enables the transfer of data via uplink (UL) and/or downlink (DL). The radio link can, for example, be established by initiating a RACH procedure at the UE 204; traffic flow via a bearer between the UE 204 and the network via the SN/SCG;

FIG. 2 illustrates an example of a method 200.

In the example of FIG. 2, a plurality of apparatuses transmit and/or receive one or more signals and/or one or more messages across a network. In examples, any suitable form of communication in any suitable network setup can be used. For example, at least a portion of the network 100 of FIG. 1 can be used.

In the illustrated example, the method 200 comprises a terminal node 110 and three network nodes in a network. In the example of FIG. 2 the terminal node 110 is a UE 204, and the network nodes are a source MN 216a, a target MN 216b and a target SN 218. In examples, the method 200, and/or parts of the method 200, can be considered a method 200 for enabling conditional handover with delayed dual connectivity.

In examples, delayed dual connectivity can be considered to be a delay in and/or delaying and/or enabling delay of and/or allowing delay of and/or facilitating delay of establishing DC configuration at a UE 204.

In some examples, delayed dual connectivity can be considered to be a delay in and/or delaying and/or enabling delay of and/or allowing delay of and/or facilitating delay of addition of a primary secondary cell after conditional handover to a primary cell has been completed.

In examples, enabling addition of a primary secondary cell based, at least in part, on an addition condition can be considered conditional addition.

In some examples, the method 200 and/or one or more methods disclosed herein can be considered method(s) for enabling conditional addition and/or method(s) for enabling delayed conditional addition.

Accordingly, in examples, the elements in the example of FIG. 2 can be considered to enable conditional handover with delayed dual connectivity and/or to be configured to enable conditional handover with delayed dual connectivity.

In examples, communications between elements illustrated in FIG. 2 can proceed via any number of intervening elements, including no intervening elements.

Although one UE 204 is illustrated in the example of FIG. 2, in examples any suitable number of UEs 204 can be included.

Similarly, in examples, any suitable number of network nodes can be included.

In the example of FIG. 2 the UE 204 is connected to the source MN 216a and is to be configured to perform/is to perform conditional handover with duel connectivity to the target MN 216b and target SN.

In examples, (not illustrated) the UE 204 can also be connected to a source SN. At block 250, at least one signal is transmitted from the target MN 216b to the source MN 216a. In the illustrated example, the at least one signal comprises configuration information 206.

In examples, at block 250, one or more messages are transmitted from the target MN 216b to the source MN 216a. The one or more messages can comprise a Handover Request Ack message.

In examples, the configuration information 206 comprises, at least: a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell.

In some examples, the configuration information 206 comprises, at least: a handover execution condition 208 for enabling conditional handover to the primary cell and an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity.

As FIG. 2 illustrates one or more actions of transmission of one or more signals, FIG. 2 also illustrates the corresponding transmitting/causing transmission feature(s)/action(s).

Similarly, for any transmitting/causing transmission feature(s)/action(s), FIG. 2 also illustrates the corresponding receiving/causing receiving feature(s)/action(s).

For example, block 250 can be considered to illustrate causing transmission of configuration information 206 comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; and an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity.

Similarly, block 250 can be considered to illustrate receiving the configuration information 206 at the source MN 216a.

In examples, the handover execution condition 208 and/or the addition condition 210 can comprise any suitable condition or conditions.

In some examples, one or more of the conditions can be radio signal conditions. For example, the handover execution condition 208 and/or addition condition 210 can be/comprise a received radio signal power condition and/or a received radio signal quality condition.

In examples, the handover execution condition 208 and/or addition condition 210 can be based on and/or related to reference signal received power (RSRP) and/or reference signal received quality (RSRQ).

In examples, the configuration information 206 comprises one or more measurement identities, for example MeaslD-1 , in relation to the primary cell and/or a measurement identity, for example MeaslD-2, in relation to the primary secondary cell.

In some examples, the handover execution condition 208 for the primary cell is event A3 condition and/or the addition condition 210 for the secondary cell is event A4 condition. For example, A3 condition can be for a measurement ID corresponding to the primary cell and A4 condition can be for a measurement ID corresponding to the primary secondary cell.

In examples, the configuration information 206 comprises: configuration information 206 for handover to the primary cell; and configuration information for enabling the delayed dual connectivity with the primary secondary cell.

In examples, the configuration information 206 can be considered to be or comprise conditional handover (CHO) configuration information and/or dual connectivity (DC) configuration information.

In some examples, the configuration information 206 comprises a timeout period value. The timeout period value can be for use by the UE 204 in enabling conditional handover with delayed dual connectivity.

In examples, the method 200 can comprise determining the configuration information. The configuration information can be determined in any suitable way and/or at any suitable network node(s).

As used herein, the term "determining" (and grammatical variants thereof) can include, not least: calculating, computing, processing, deriving, investigating, looking up (for example, looking up in a table, a database or another data structure), ascertaining and the like. Also, "determining" can include receiving (for example, receiving information), accessing (for example, accessing data in a memory) and the like. Also, "determining" can include resolving, selecting, choosing, establishing, and the like.

In examples, the target MN 216b is configured to determine and/or determines at least part of the configuration information 206.

In FIG. 2, the configuration information 206 is received by the source MN 216a and, at block 252, at least one signal and/or at least one message comprising the configuration information is transmitted from the source MN 216a to the UE 204.

In examples, the at least one message comprises an RRCReconfiguration message.

In examples, the source MN 216a can change, and/or amend, and/or augment and/or alter the configuration information 206.

In some examples, the source MN 216a can add to the configuration information a timeout period value. The time out period value can be for use by the UE 204 in enabling conditional handover with delayed dual connectivity.

In the illustrated example, the configuration information 206 is received by the UE 204.

Accordingly, FIG. 2 illustrates, from the perspective of the UE 204, receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell.

At block 254, the method 200 comprises determining, by the UE 204, whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied.

Any suitable method for determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied can be used. In examples, determining whether the handover execution condition 208 for the primary cell is satisfied and/or determining whether the addition condition 210 for the primary secondary cell is satisfied comprises determining and/or making one or more measurements.

In some examples, determining whether the handover execution condition 208 for the primary cell is satisfied comprises performing and/or making one or more measurements and/or determining whether the addition condition 210 is satisfied comprises performing and/or making one or more separate measurements.

In examples the one or more measurements comprise one or more radio signal measurements. For example, received radio signal quality and/or received radio signal strength and so on.

Accordingly, in some examples, the method 200 comprises performing one or more measurement for/in relation to the handover execution condition 208 for a primary cell and performing one or more separate measurements for the addition condition 210 for/in relation to a primary secondary cell.

In some examples determining whether the handover execution condition 208 for the primary cell is satisfied comprises monitoring the primary cell and/or determining whether the addition condition 210 for the primary secondary cell is satisfied comprises monitoring the primary secondary cell.

The handover execution condition 208 for the primary cell can be satisfied independently of the addition condition 210 for the primary secondary cell, and vice versa.

At block 256, the method 200 comprises if it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

Any suitable method for enabling completion of conditional handover to the primary cell can be used. In examples, enabling completion of conditional handover to the primary cell comprises transmitting one or more signals and/or messages to the target MN 216b and/or receiving one or more signals and/or messages from the target MN 216b.

This is illustrated in the example of FIG.2 by the double headed arrow 213 between block 256 and the target MN 216b.

In examples, enabling completion of conditional handover to the primary cell comprises causing performance of and/or performing a random access procedure/process, for example a RACH procedure/process, with the target MN 216b.

In some examples, enabling completion of conditional handover and conditional addition comprises establishing an active radio link.

In examples, actions performed with the primary cell and/or target MN 216b to enable completion of conditional handover to the primary cell can be performed similarly with the primary secondary cell and/or target SN 218 to enable completion of addition of the primary secondary cell for dual connectivity.

Accordingly, in examples, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity comprises not performing and/or withholding and/or preventing such actions with the target SN 218.

For example, not performing and/or withholding and/or preventing: transmitting one or more signals and/or messages to the target SN 218, and/or receiving one or more signals and/or messages from the target SN 218, and/or performing a random access procedure/process with the target SN 218, and/or establishing an active radio link with the target SN 218.

In examples, at block 256, from the network perspective, one or more SCG bearers of the target SN 218 are and/or have been prepared and/or initiated but not activated and/or accessed by the UE 204. In some examples, it can be considered that at block 256, SCG bearer(s) of the target SN 218 cannot be used and/or SCG traffic of the target SN 218 cannot occur. In examples, the PSCell and/or the SCG of the target SN 218 and/or the target SN 218 can be considered suspended.

In examples, completion of conditional handover to the primary cell is enabled, without enabling completion of conditional addition to the primary secondary cell for dual connectivity, after a timeout period has expired after the handover execution condition 208 for the primary cell is satisfied.

That is, in examples when the UE 204 determines that the handover execution condition 208 for the primary cell is satisfied, the UE 204 can start a timer and enables completion of conditional handover to the primary cell after a timeout period has expired and/or a predetermined time interval passes.

The timer can be considered timer TMN-switch.

In examples, the method 200 comprises receiving the timeout period value. For example, the UE 204 can receive the timeout period value/timer value in the configuration information 206. See, for example, block 252.

Any suitable timeout period value can be used. For example, a timeout period value in the range 10 milliseconds to 100 milliseconds can be used.

In examples, a timeout period in the range 25 milliseconds to 75 milliseconds can be used.

In examples, a timeout period in the range 35 milliseconds to 65 milliseconds can be used.

In some examples, a timeout period of or of approximately or substantially 50 milliseconds can be used.

In examples where a timer is used by the UE 204, completion of conditional handover to the primary cell can be enabled prior to expiry of the timeout period.

For example, completion of conditional handover to the primary cell can be enabled if T310 for the source PCell starts. Accordingly, in examples, completion of conditional handover to the target primary cell can be enabled if the connection to the source PCell begins to degrade and/or fail.

At block 258, at least one signal and/or at least one message is transmitted from the UE 204 to the target MN 216b.

In examples, the at least one signal and/or message comprises information configured to indicate that the handover to the primary cell is complete. In examples, the at least one message can be considered a HO complete message. In some examples the at least one message comprises an RRC Reconfiguration Complete message.

Any suitable information configured to indicate that the handover to the primary cell is complete can be used.

In some examples, the at least one signal and/or at least one message comprises information configured to provide an indication of the primary secondary cell conditional addition status.

Therefore, in examples, the method 200 comprises causing transmission, to a network node, of information configured to provide an indication of the primary secondary cell conditional addition status.

In examples, the indication of the primary secondary cell conditional addition status comprises at least one of: an indication that the addition condition 210 for the primary secondary cell is not yet satisfied, an indication that an active radio link with the primary secondary cell is not yet established, and where a timeout period is used, a value of a timeout period timer.

In some examples, the at least one signal and/or at least one message comprises information indicative of one or more measurement results of the primary secondary cell. In examples, the at least one signal and/or at least one message comprise one or more measurement results of the primary secondary cell.

Therefore, in examples, the method 200 comprises causing transmission of information indicative of one or more measurement results of the primary secondary cell. Accordingly, in examples the UE 204 can be considered to be configured to inform and/or to inform the target MN 216b of one or more aspects of the primary secondary cell conditional addition status.

This can allow, for example, the network to manage resources appropriately, for example at the Target SN 218.

At block 260, at least one signal and/or at least one message is transmitted from the target MN 216b to the target SN 218. In examples, the at least one message can comprise a SgNB Reconfiguration complete message.

In examples, the at least one signal and/or at least one message is configured to inform the target SN 218 that the UE 204 is not yet available.

Accordingly, in examples, the method 200 comprises informing a target SN that the UE 204 is not yet available.

In some examples, the at least one signal and/or at least one message comprises information configured to indicate that the UE 204 is not yet available. Any suitable information configured to indicate that the UE 204 is not yet available can be used.

In examples, the at least one signal and/or at least one message comprises at least a portion of the information configured to provide an indication of the primary secondary cell conditional addition status, received by the target MN 216b at block 258.

In examples, the target MN 216b informs the target SN 218 about the UE 204 not yet being available to ensure that the primary secondary cell/SCG connection is retained even if the UE 204 has not accessed the primary secondary cell and/or to allow the network to release the suspended SCG if it is no longer determined to be useful.

With regard to the SN 218, the method 200 can be considered to comprise receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE 204 for later enabling addition of the primary secondary cell for dual connectivity at the UE 204, when the addition condition for the primary secondary cell is satisfied. See, for example, block 262. In examples any suitable indication that an addition condition for a primary secondary cell is not satisfied can be used. For example, the at least one signal and/or at least one message received by the target SN 218 at block 260 can be considered to comprise and/or be an indication that an addition condition for a primary secondary cell is not satisfied.

In examples, the information configured to provide an indication of the primary secondary cell conditional addition status can be considered to be and/or comprise or be comprised in the indication that an addition condition for a primary secondary cell is not satisfied.

In the example of FIG. 2, the target SN 218 maintains resources for the UE 204, based at least in part on the received indication, to enable or allow later addition of the primary secondary cell for dual connectivity at the UE 204. See, for example, block 262.

In examples, the UE 204 continues to monitor the primary secondary cell to determine whether the addition condition 210 for the primary secondary cell is satisfied.

Accordingly, in examples, the method 200 comprises determining, by a UE 204, whether the addition condition 210 for the primary secondary cell is satisfied after it is determined that the handover execution condition 208 for the primary cell is satisfied.

In some examples, the method 200 comprises determining, by a UE 204, whether the addition condition 210 for the primary secondary cell is satisfied after conditional handover to the primary cell/target MN 216b is completed.

In the example of FIG. 2, at a later time it is determined that the addition condition 210 for the primary secondary cell is satisfied.

At block 262 the method 200 comprises enabling completion of conditional addition to the primary secondary cell for dual connectivity.

Accordingly, in examples, the method 200 comprises if it is determined at a later time that the addition condition 210 for the primary secondary cell is satisfied, enabling completion of conditional addition of the primary secondary cell for dual connectivity.

Any suitable method for enabling completion of addition of the primary secondary cell can be used. In examples, block 262 can be as described in relation enabling conditional handover to the primary cell at block 256 but with respect to the primary secondary cell instead of the primary cell.

From the perspective of the target SN 218, in the example of FIG. 2, the method 200 therefore can be considered to comprise subsequently enabling completion of addition of the primary secondary cell for dual connectivity.

At block 264, at least one signal and/or at least one message is transmitted from the target SN 218 to the target MN 216b.

In examples, the at least one signal and/or message comprises information configured to indicate that the handover to the primary secondary cell is complete. In some examples the at least one message comprises an SCG activation indication.

Any suitable information configured to indicate that the handover to the primary secondary cell is complete can be used.

From the perspective of the target SN 218, in the example of FIG. 2, the method 200 therefore can be considered to comprise informing a master node 216b that addition of the primary secondary cell for dual connectivity has been completed.

In examples, if the addition condition 210 for the primary secondary cell is met first, the UE 204 waits until the handover execution condition 208 for the primary cell is met. When the handover execution condition 208 for the primary cell is met, the LIE 204 enables completion of conditional handover to the primary cell and again checks if the addition condition 210 is satisfied.

If the addition condition 210 is no longer satisfied the UE 204 can enable completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

In examples, from the network perspective, the method 200 comprises receiving an indication, from the UE 204, that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

Any suitable indication received in any suitable way can be used. For example, with regard to FIG. 2 information received by the target MN 216b at block 256 and/or 258 can be considered to provide such an indication.

In examples, enabling delay of addition of the primary secondary cell can comprise performing and/or not performing one or more actions.

For example, informing target SN 218 at block 260 that the UE 204 is not yet available can form at least part of enabling delay of addition of the primary secondary cell.

In examples, the method 200 comprises enabling completion of conditional handover to the primary cell without dual connectivity to the primary secondary cell and enabling initiation, but not completion, of addition with dual connectivity to the primary secondary cell.

For example, one or more resources can be reserved at the target SN 218 and/or one or more bearers mapped to the target SN 218/SCG, without access/activation.

In some examples, enabling completion of conditional handover to the primary cell and/or enabling delay of addition of the primary secondary cell for dual connectivity and/or enabling completion of addition of the primary secondary cell for dual connectivity comprises remapping bearers.

For example, SCG bearers can be remapped to MCG if addition condition 210 is not yet met and/or MCG bearers can be remapped to SCG upon completion of addition of the primary secondary cell for dual connectivity.

Examples of the disclosure are advantageous. For example, examples of the disclosure provide for the triggering condition with CHO to be decided in a flexible manner.

In examples, CHO can be executed with suspended SCG, which means, for example, that CHO is not delayed by waiting for suitable SCG. Furthermore, in examples, CHO can be executed if source radio condition degrades (T310 starts), with suspended SCG.

FIG. 3 illustrates an example of a method 300.

In examples, the method 300 can be performed by any suitable apparatus comprising any suitable means for performing the method 300. For example, an apparatus as described in relation to FIGS 8A and/or 8B.

In examples, the method 300 can be performed by a UE 204, such as a UE 204 of FIG 1 and/or FIG 2.

In examples, the method 300, and/or at least a part of the method 300, can be considered a method 300 for enabling conditional handover with delayed dual connectivity.

At block 302, the method 300 comprises receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell.

At block 304, the method 300 comprises determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied.

If it is determined that the handover condition for the primary cell is not satisfied the method 300 proceeds back to block 304.

If it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied the method 300 proceeds to block 306.

At block 306, the method 300 comprises enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

If, at a later time, the addition condition 210 for the primary secondary cell is satisfied the method 300 proceeds to block 308. At block 308 the method 300 comprises enabling completion of conditional addition of the primary secondary cell for dual connectivity.

However, in examples, the method 300 does not proceed to block 308.

Consequently, FIG. 3 illustrates a method 300 comprising: enabling conditional handover with delayed dual connectivity by: receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell; determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied; and if it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

FIG. 4 illustrates an example of a method 400.

In examples, the method 400 can be performed by any suitable apparatus comprising any suitable means for performing the method 400.

For example, an apparatus as described in relation to FIGS 8A and/or 8B.

In examples, the method 400 can be performed by one or more network nodes, such as a target MN 216b of FIG 2.

In examples, the method 400, and/or at least a part of the method 400, can be considered a method 400 for enabling conditional handover with delayed dual connectivity.

At block 402 the method 400 comprises causing transmission of configuration information 206 comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity.

At block 404 the method 400 comprises receiving an indication, from the UE 204 that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied.

At block 406 the method 400 comprises enabling completion of conditional handover to the primary cell.

At block 408 the method 400 comprises enabling delay of addition of the primary secondary cell for dual connectivity.

Consequently, FIG. 4 illustrates a method 400 comprising: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: causing transmission of configuration information 206 comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE 204 that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition to the primary secondary cell for dual connectivity.

FIG. 5 illustrates an example of a method 500.

In examples, the method 500 can be performed by any suitable apparatus comprising any suitable means for performing the method 500.

For example, an apparatus as described in relation to FIGS 8A and/or 8B. In examples, the method 500 can be performed by one or more network nodes, such as a target SN 218 of FIG 2.

In examples, the method 500, and/or at least a part of the method 500, can be considered a method 500 for enabling conditional handover with delayed dual connectivity.

At block 502 the method 500 comprises receiving an indication that an addition condition 210 for a primary secondary cell is not satisfied.

At block 504 the method 500 comprises maintaining resources for the UE 204 for later enabling addition of the primary secondary cell for dual connectivity at the UE 204, when the addition condition 210 for the primary secondary cell is satisfied.

Consequently, FIG. 5 illustrates a method 500 comprising: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.

FIG. 6 illustrates an example of a method 600.

Some examples relate to third generation Partnership Project (3GPP) network. FIG. 6 can be considered to illustrate some such examples.

The following description can be considered to illustrate some such examples.

Examples of the disclosure propose an extension for Radio Resource Control (RRC) Signaling message to allow CHO configuration for DC (i.e. containing an MCG configuration and SCG configuration), more specifically the following:

Modify the CHO configuration to consider a Measurement Identifier 1 (MeaslD-1) and a Measurement Identifier 2 (Meas-ID-2) for the target PCell and target PSCell, respectively. Allow Event A4 for the measurement ID corresponding to PSCell.

When the above extensions are specified in the New Radio (NR) RRC specification the target CHO configuration can be applied as follows.

When the first condition is met (for the PCell), UE 204 either starts timer, Tmn-switch, for second condition (for the PSCell) to meet (Case 2, timer is configured) or immediately proceeds with checking the second condition (Case 1 , timer is not configured).

Case 1 (Timer is not configured): If the timer for the second condition is not configured, the UE 204 detaches from source MN 216a and SN when the first condition is met and performs CHO to the new target MN 216b without accessing the SCG. The access to the SCG is performed when the second condition is met later (and considers the SCG as suspended until then).

Case 2 (Timer is configured): If second condition is not met within the expiry of the specified timer Tmn-switch or until T310 (for source PCell) starts, the UE 204 can proceed with execution of CHO without accessing the SCG.

Similar to case 1 , the access to the SCG is performed when the second condition is met later.

In both cases 1 and 2, the UE 204 includes in RRC (Connection) Reconfiguration Complete sent to the target MN during CHO an indication about the “SCG condition”, for example, (1) SCG access condition is not yet met and/or (2) SCG is suspended and/or (3) SCG is not added yet, second condition timer value, and so on.

Additionally, or alternatively, measurement results pertaining to the SCG or SCells may be appended to the HO complete message (which can include indication about whether the SCG/SCells are detectable, and/or any Radio Resource Management (RRM)/Channel State Information (CSI) measurement information is available).

The network may inform the target SCG about the UE 204 not being available at this time to ensure the SCG connection is still retained even if the UE 204 didn’t access the cell immediately, or to allow network to release the suspended SCG if it’s not seen useful. Later on, when the second condition is met for PSCell, UE 204 triggers the RACH Access and completes the SCG activation.

If the second condition for PSCell is met first, the UE 204 waits until the first condition for PCell is met. When CHO condition is met later, the UE 204 executes the CHO but for the access of the PSCell/SCG UE 204 may check either 1) if entering criteria of the measurement event corresponding to the second condition is still met or 2) the leaving criteria of the measurement event corresponding to the second condition is not met.

If 1) or 2) is not fulfilled, the UE 204 may continue to monitor the second condition. This is to account for any possible radio changes of PSCell while waiting for the first condition to be fulfilled.

With reference to the example of FIG. 6:

CHO Handover Preparation Phase:

• Step 1 , 2: Target master node 216b decides to prepare new SCG as part of CHO Handover preparation. For example, at the step 1 , the source MN 216a transmits to the target MN 216b the Handover request message including information indicating whether the UE and source MN are able to support the DC-HO. At the step 2, the target MN performs SCG preparation with target SN 218.

• Step 3, 4: Target master node 216b also includes measurement ID in the measurement config of target SCG linked to condition for UE 204 to start the SCG Access (condition for delayed SCG access). For example, at the step 3, the target MN 216b includes one or more measIDs for the conditional activation of SCG in the target measurement configuration information.

At the step 4, the target MN 216b informs this measurement condition also to the Source MN 216a using “Handover Request ACK”. More specifically, the target MN 216b transmits the Handover request ACK message to the Source MN 216a in response to the Handover Request message. The Handover request ACK message includes SCG measurement configuration information for DC-CHO, SCell frequency information and an event A4 Threshold information. • Step 5: The source MN 216a transmits an RRC Reconfiguration message includes CHO configuration for the target DC with two measurement IDs (for example, measlD-1 for Pcell, measlD-2 for PSCell). For example, the RRC Reconfiguration message includes CHO configuration information and timer information for PSCell event. The CHO configuration information includes measurement information related to the measurement ID-1 and measurement information related to the measurement ID-2.

In examples, there are two options for the step 5 (options 5-1 and 5-2) for providing the RRC reconfiguration with CHO configuration for target DC.

• Option 5-1 : Provide only one CHO configuration containing only MCG configuration with bearers mapped only to MN

• Option 5-2: DC configuration containing MCG+SCG configures with bearer using SCG resources

A new parameter on the dependency between the measurement ID and Timer for measurement ID-2 can be provided: o Measurement ID-1 (measlD-1) AND Measurement ID-2 (measlD-2) -> Conditional Reconfiguration contents will be executed o Measurement ID-1 AND Timer expires for Measurement ID-2 (measlD-2) Conditional Reconfiguration with Target SCG condition.

At the step 5, in Rel-16 of the 3GPP RRC specification in TS 38.331 in section 6.2.2 message definitions, RRCReconfiguration message contains a conditionalReconfiguration- r16 that includes the conditional configuration for a PCell or PSCell (for CHO or CPC purposes).

More specifically the CondReconfigToAddMod can be adapted by including the following: condRRCReconfig to be extended to include one SCG configuration which means the RRCReconfiguration message provides for exactly one CG-Config instance to the CHO execution condition define by condExecutionCond.

For a given target MN where {MCG, SCG} are provided by the condRRCReconfig extend the condExecutionCond IE to add up to 2 more measld to also include the PSCell.

At the step 6a, the UE applies the CHO configuration informed by the RRC reconfiguration message of the step 5 for the conditional handover measurement for the PCell (measlD-1) and target PSCell measurement (measlD-2) In the example of FIG. 6, timer expires for measurement ID-2, at the Step 6b, the UE 204 executes CHO with target MN 216b and includes parameter ‘SCG condition’ in the Handover complete message that SCG is, for example, suspended or not yet accessed. The Handover complete message can be the RRC reconfiguration Complete message and the RRC reconfiguration Complete message further includes SCell measurement results which has measured based on addition condition information and measurement information for the secondary cells.

At the step 6b, the function of the RRC reconfiguration message can be varied depending on the options 5-1 and 5-2.

• If Option 5-1 above is followed, the Target MN 216b remaps the SCG bearers on MCG when the SCG is activated and target MN 216b sends RRCReconfiguration for bearer remapping to the SCG.

• If Option 5-2 is followed, when first condition is met, UE 204 applies the CHO configuration. When a second condition for PSCell applies, the UE applies the DC configuration. Herein, the interruption on SCG bearer is avoided (until they are activated once second condition is met). We save also the transmission of an additional RRC Reconfiguration for remapping the SCG bearer on MCG.

• Step 7b: If the target MN 216b intends to continue with the SCG condition, it informs Target SN 218 to wait for additional time for completion of SCG activation by sending the SgNB Reconfiguration Complete message.

After the UE performs the CHO, the UE continues measurements based on measurement I Ds for conditional dual connectivity, at the step 8b. For example, if the meas I D-2 condition is met at the step 9b, the UE is able to access to the PSCell managed by the Target SN 218 at the step 10b. After then, the UE initiates a RACH procedure to activate the SCG at the step 11 b. And the target SN transmits the SCG Activation Indication message to the target MN in order to indicate the activated status (and complementing step 7b) .

During the steps 8b-12b, the SCG condition is SCG Suspend, if there were some SN terminated bearers initially mapped to the SN during the CHO execution. Herein, there can be a need to suspend a cell or reconfigure the measurement condition from A4 to A1 (as this is a valid SCell for the UE 204 but not activated).

FIG. 7 illustrates an example of a method 600. The example of FIG. 7 illustrates an alternative to FIG. 6 after step 6a.

With reference to the example of FIG. 7: at the step 6a, the UE 204 applies CHO configuration and release the measurement IDs for conditional activation if both conditions are met. That is to say, the UE 204 applies the target configuration without any changes. But can release the measurement-1 D associated with conditional activation (because this is not needed in this case).

At the step 7a, the UE transmits the RA and RRC reconfiguration complete message to the target MN 216b. The RRC reconfiguration complete message includes the SCG condition (in this case signalling that SCG is activated) and SCell measurement results for the one or more secondary cells. At the step 8a, the target 216b transmits SgNB Reconfiguration Complete message to the SN 218. The UE performs the RACH procedure to activate SCG with the SN 218, at the step 9a.

The UE 204 may also indicate the SCG status (i.e. SCG condition and SCell measurements) to the MCG.

Examples of the disclosure are advantageous.

For example, a technical benefit provided by examples of the disclosure is allowing access of the PSCell/SCG to be de-coupled from access of the PCell in inter-MN handover with SN.

In examples, access of the PSCell/SCG is performed only when a separate second condition is met which provides robustness for the PSCell/SCG access.

Similarly, examples of the disclosure provide for more robust DC setup during CHO handover.

Fig 8A illustrates an example of an apparatus 130. The apparatus 130 may be a controller of an apparatus or device such as a terminal node 110, for example UE 204, or network element 216a, 216b and/or 218, such as an eNB or gNB.

Implementation of apparatus 130 may be as controller circuitry. The apparatus 130 may be implemented in hardware alone, have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware). As illustrated in Fig 8A the apparatus 130 may be implemented using instructions that enable hardware functionality, for example, by using executable instructions of a computer program 136 in a general-purpose or special-purpose processor 132 that may be stored on a computer readable storage medium (disk, memory etc.) to be executed by such a processor 132.

The processor 132 is configured to read from and write to the memory 134. The processor 132 may also comprise an output interface via which data and/or commands are output by the processor 132 and an input interface via which data and/or commands are input to the processor 132.

The memory 134 stores a computer program 136 comprising computer program instructions (computer program code) that controls the operation of the apparatus 130 when loaded into the processor 132. The computer program instructions, of the computer program 136, provide the logic and routines that enables the apparatus 130 to perform at least a portion of the methods illustrated in Figs 2 and/or 3 and/or 4 and/or 5 and/or 6. The processor 132 by reading the memory 134 is able to load and execute the computer program 136.

In examples, the apparatus 130 therefore comprises: at least one processor 132; and at least one memory 134 including computer program code the at least one memory 134 and the computer program code configured to, with the at least one processor 132, cause the apparatus 130 at least to perform: enabling conditional handover with delayed dual connectivity by: receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell; determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied; and if it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

In examples, the apparatus 130 therefore comprises: at least one processor 132; and at least one memory 134 including computer program code the at least one memory 134 and the computer program code configured to, with the at least one processor 132, cause the apparatus 130 at least to perform: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: causing transmission of configuration information 206 comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE 204 that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

In examples, the apparatus 130 therefore comprises: at least one processor 132; and at least one memory 134 including computer program code the at least one memory 134 and the computer program code configured to, with the at least one processor 132, cause the apparatus 130 at least to perform: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: receiving an indication that an addition condition 210 for a primary secondary cell is not satisfied; and maintaining resources for the UE 204 for later enabling addition of the primary secondary cell for dual connectivity at the UE 204, when the addition condition 210 for the primary secondary cell is satisfied.

As illustrated in Fig 8A, the computer program 136 may arrive at the apparatus 130 via any suitable delivery mechanism 162. The delivery mechanism 162 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 record medium such as a Compact Disc Read-Only Memory (CD-ROM) or a Digital Versatile Disc (DVD) or a solid state memory, an article of manufacture that comprises or tangibly embodies the computer program 136. The delivery mechanism may be a signal configured to reliably transfer the computer program 136. The apparatus 130 may propagate or transmit the computer program 136 as a computer data signal.

Computer program instructions for causing an apparatus to perform at least the following or for performing at least the following: enabling conditional handover with delayed dual connectivity by: receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell; determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied; and if it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

Computer program instructions for causing an apparatus to perform at least the following or for performing at least the following: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: transmitting configuration information 206 comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE 204 that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition to the primary secondary cell for dual connectivity.

Computer program instructions for causing an apparatus to perform at least the following or for performing at least the following: enabling conditional handover with delayed dual connectivity at a UE 204 by: receiving an indication that an addition condition 210 for a primary secondary cell is not satisfied; and maintaining resources for the UE 204 for later enabling addition of the primary secondary cell for dual connectivity at the UE 204, when the addition condition 210 for the primary secondary cell is satisfied.

The computer program instructions may be comprised 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 134 is illustrated 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.

In examples the memory 134 comprises a random access memory 158 and a read only memory 160. In examples the computer program 136 can be stored in the read only memory 158. See, for example, Fig. 8B

In some examples the memory 134 can be split into random access memory 158 and read only memory 160.

Although the processor 132 is illustrated 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. The processor 132 may be a single core or multi-core processor.

References to ‘computer-readable storage medium’, ‘computer program product’, ‘tangibly embodied computer program’ etc. or a ‘controller’, ‘computer’, ‘processor’ etc. should be understood to encompass not only computers having different architectures such as single /multi- processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for 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) hardware-only circuitry implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable):

(i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and

(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g. firmware) for operation, but the software may not be present when it is not needed for operation.

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

The blocks illustrated in the Figs 2 and/or 3 and/or 4 and/or 5 and/or 6 and/or 7 may represent steps in a method and/or sections of code in the computer program 136. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted.

For example, blocks 262 and 264 of FIG. 2 can be omitted. Similarly block 308 can, in examples, be omitted.

Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described. Thus, the apparatus 130 can, in examples, comprise means for: enabling conditional handover with delayed dual connectivity by: receiving configuration information 206 comprising at least a handover execution condition 208 for a primary cell and an addition condition 210 for a primary secondary cell; determining whether the handover execution condition 208 for the primary cell is satisfied and whether the addition condition 210 for the primary secondary cell is satisfied; and if it is determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

Thus, the apparatus 130 can, in examples, comprise means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: causing transmission of configuration information comprising at least: a handover execution condition 208 for a primary cell for enabling conditional handover to the primary cell; an addition condition 210 for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE 204 that the UE 204 has determined that the handover execution condition 208 for the primary cell is satisfied but the addition condition 210 for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

Thus, the apparatus 130 can, in examples, comprise means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE 204, by: receiving an indication that an addition condition 210 for a primary secondary cell is not satisfied; and maintaining resources for the UE 204 for later enabling addition of the primary secondary cell for dual connectivity at the UE 204, when the addition condition 210 for the primary secondary cell is satisfied. In examples, an apparatus 130 can comprise means for performing one or more methods, or at least part of one or more methods, as disclosed herein.

In examples, an apparatus 130 can be configured to perform one or more methods, or at least a part of one or more methods, as disclosed herein.

The above described examples find application as enabling components of: automotive systems; telecommunication systems; electronic systems including consumer electronic products; distributed computing systems; media systems for generating or rendering media content including audio, visual and audio visual content and mixed, mediated, virtual and/or augmented reality; personal systems including personal health systems or personal fitness systems; navigation systems; user interfaces also known as human machine interfaces; networks including cellular, non-cellular, and optical networks; ad-hoc networks; the internet; the internet of things; virtualized networks; and related software and services.

The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to “comprising only one..” or by using “consisting”.

In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’ or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be 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.

Features described in the preceding description may be used in combinations other than the combinations explicitly described above.

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

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

The term ‘a’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a/the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning.

The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The 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 description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described.

Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not emphasis has been placed thereon. l/we claim:

Claims

46 WE CLAIM:

1. An apparatus comprising means for: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

2. An apparatus as claimed in claim 1, wherein the means are configured to, if it is determined at a later time that the addition condition for the primary secondary cell is satisfied, enable completion of conditional addition of the primary secondary cell for dual connectivity.

3. An apparatus as claimed in claim 1 or 2, wherein enabling the completion of conditional handover and the completion of the conditional addition comprises establishing an active radio link.

4. An apparatus as claimed in any preceding claim, wherein the completion of conditional handover to the primary cell is enabled, without enabling the completion of conditional addition to the primary secondary cell for dual connectivity, after a timeout period has expired after the handover execution condition for the primary cell is satisfied.

5. An apparatus as claimed in claim 4, wherein the means are configured to receive the timeout period value.

6. An apparatus as claimed in any preceding claim, wherein the means are configured to cause transmission, to a network node, of information configured to provide an indication of the primary secondary cell conditional addition status.

7. An apparatus as claimed in claim 6, wherein the indication of the primary secondary cell conditional addition status comprises at least one of: 47 an indication that the addition condition for the primary secondary cell is not yet satisfied; an indication that an active radio link with the primary secondary cell is not yet established; and where a timeout period is used, a value of a timeout period timer.

8. An apparatus as claimed in any preceding claim, wherein the handover execution condition for the primary cell is A3 condition and/or the addition condition for the primary secondary cell is A4 condition.

9. An apparatus as claimed in any preceding claim, wherein the means are configured to cause transmission of information indicative of one or more measurement results of the primary secondary cell.

10. An apparatus as claimed in any preceding claim, wherein the configuration information comprises: configuration information for handover to the primary cell; and configuration information for enabling the delayed dual connectivity with the primary secondary cell.

11. A method comprising: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

12. A method as claimed in claim 11, wherein the method comprises, if it is determined at a later time that the addition condition for the primary secondary cell is satisfied, enabling completion of conditional addition of the primary secondary cell for dual connectivity. 48

13. A method as claimed in claim 11 or 12, wherein enabling the completion of conditional handover and the completion of conditional addition comprises establishing an active radio link.

14. A method as claimed in any of claims 11 to 13, wherein the completion of conditional handover to the primary cell is enabled, without enabling the completion of conditional addition to the primary secondary cell for dual connectivity, after a timeout period has expired after the handover execution condition for the primary cell is satisfied.

15. A method as claimed in claim 14, wherein the method copmrises receiving the timeout period value.

16. A method as claimed in any of claims 11 to 15, wherein the method comprises causing transmission, to a network node, of information configured to provide an indication of the primary secondary cell conditional addition status.

17. A method as claimed in claim 16, wherein the indication of the primary secondary cell conditional addition status comprises at least one of: an indication that the addition condition for the primary secondary cell is not yet satisfied; an indication that an active radio link with the primary secondary cell is not yet established; and where a timeout period is used, a value of a timeout period timer.

18. A method as claimed in any of claims 11 to 17, wherein the handover execution condition for the primary cell is A3 condition and/or the addition condition for the primary secondary cell is A4 condition.

19. A method as claimed in any of claims 11 to 18, wherein the method comprises causing transmission of information indicative of one or more measurement results of the primary secondary cell.

20. A method as claimed in any of claims 11 to 19, wherein the configuration information comprises: configuration information for handover to the primary cell; and configuration information for enabling the delayed dual connectivity with the primary secondary cell.

21. A computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity by: receiving configuration information comprising at least a handover execution condition for a primary cell and an addition condition for a primary secondary cell; determining whether the handover execution condition for the primary cell is satisfied and whether the addition condition for the primary secondary cell is satisfied; and if it is determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied, enabling completion of conditional handover to the primary cell without enabling completion of addition of the primary secondary cell for dual connectivity.

22. An apparatus comprising means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: causing transmission of configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

23. An apparatus as claimed in claim 22, wherein the means are configured to enable the completion of conditional handover to the primary cell without dual connectivity to the primary secondary cell and enable initiation, but not completion, of addition with dual connectivity to the primary secondary cell.

24. An apparatus as claimed in claim 22 or 23, wherein enabling the completion of conditional handover to the primary cell and/or enabling the delay of addition of the primary secondary cell for dual connectivity comprises remapping bearers.

25. An apparatus as claimed in any of claims 22 to 24, wherein the means are configured to inform a target secondary node that the UE is not yet available.

26. An apparatus as claimed in any of claims 22 to 25, wherein the configuration information comprises a timeout period value.

27. A method comprising: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: causing transmission of configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition to the primary secondary cell for dual connectivity.

28. A method as claimed in claim 27, wherein the method comprises enabling the completion of conditional handover to the primary cell without dual connectivity to the primary secondary cell and enable initiation, but not completion, of addition with dual connectivity to the primary secondary cell.

29. A method as claimed in claim 27 or 28, wherein enabling the completion of conditional handover to the primary cell and/or enabling the delay of addition of the primary secondary cell for dual connectivity comprises remapping bearers.

30. A method as claimed in any of claims 27 to 29, wherein the method comprises informing a target secondary node that the UE is not yet available.

31 . A computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: transmitting configuration information comprising at least: a handover execution condition for a primary cell for enabling conditional handover to the primary cell; an addition condition for a primary secondary cell for enabling conditional handover to the primary cell without enabling addition of the primary secondary cell for dual connectivity; receiving an indication, from the UE that the UE has determined that the handover execution condition for the primary cell is satisfied but the addition condition for the primary secondary cell is not satisfied; enabling completion of conditional handover to the primary cell; and enabling delay of addition of the primary secondary cell for dual connectivity.

32. An apparatus comprising means for: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.

33. An apparatus as claimed in claim 32, wherein the means are configured to subsequently enable completion of addition of the primary secondary cell for dual connectivity.

34. An apparatus as claimed in claim 32 or 33, wherein the means are configured to inform a master node that addition of the primary secondary cell for dual connectivity has been completed.

35. A method comprising: 52 enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.

36. A computer program comprising instructions for causing an apparatus to perform at least the following: enabling conditional handover with delayed dual connectivity at a user equipment, UE, by: receiving an indication that an addition condition for a primary secondary cell is not satisfied; and maintaining resources for the UE for later enabling addition of the primary secondary cell for dual connectivity at the UE, when the addition condition for the primary secondary cell is satisfied.