Patent Description:
<NPL> relates to how handover based on a configured condition can be performed. <NPL> relates to a discussion about a DC based handover with conditional rold change for <NUM> interruption handover. <CIT> is also considered to be relevant prior art for novelty purposes under the provisions of Article <NUM>(<NUM>) EPC.

Further advantageous embodiments are set out in the dependent claims.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with performing a combination of handover techniques, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively.

In some aspects, UE <NUM> may include means for receiving, from a source base station (BS), an indication that the UE is to perform a conditional handover from the source BS to a target BS and is to perform at least one of: a two protocol stack handover from the source BS to the target BS, or a dual connectivity handover from the source BS to the target BS; means for performing the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover based at least in part on the indication; and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

In some aspects, base station <NUM> may include means for determining that a user equipment (UE) is to perform a conditional handover from the source BS to a target BS and is to perform at least one of: a two protocol stack handover from the source BS to the target BS, or a dual connectivity handover from the source BS to the target BS; means for transmitting, to the UE, an indication that indicates that the UE is to perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover; and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

A source BS (e.g., a serving BS, etc.) may perform a handover of a UE to a target BS. For example, a UE in motion may be handed over from one BS to another as the UE moves through cells provided by different BSs.

Mobility enhancements for UE handover may have certain design targets, such as approximately zero millisecond handover interruption latency (e.g., for real-time gaming applications and other ultra-reliable low latency communications (URLLC) applications), a handover reliability, reduced handover ping-pongs, and/or the like. To satisfy these design targets, various types of handover enhancements may be used. For example, a dual connectivity handover may be used, an enhanced make-before-break (MBB) handover (e.g., a low latency or a zero latency handover, a two protocol stack handover, and/or the like), and/or a conditional handover may be used to improve a signaling reliability and/or to reduce ping-pongs associated with a handover. A two protocol stack handover may be referred to as a dual active protocol stack-based handover.

Continuing with the previous examples, these techniques may include dual Rx/dual Tx, dual Rx/single Tx, single Rx/single Tx, dual PHY, dual L2 stack (e.g., media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or the like) during handover, security key switch during handover, PDCP sequence number continuity after handover, support for both intra-frequency and inter-frequency BS handover, support for synchronous and asynchronous BS handover, random access channel (RACH)-based handover, and/or the like. Continuing still with the previous example, a handover according to these techniques may include a multi-phase handover where two protocol stacks are used to handover the UE from a source BS to a target BS (e.g., a first protocol stack is used for continued communications with the source BS while the second protocol stack is used for handover of the UE from the source BS to the target BS). While these techniques may facilitate satisfaction of design targets related to reliability and/or latency, these techniques may experience a threshold handover failure rate, a threshold amount of ping-pong handover signaling, and/or the like.

Some techniques and apparatuses described herein provide for using a combination of handover techniques to perform a handover of a UE from a source BS to a target BS. For example, some techniques and apparatuses described herein provide a UE and/or a source BS that are capable of using a combination of a two protocol stack handover (sometimes referred to as a dual active protocol stack-based handover), a conditional handover, and/or a dual connectivity handover to perform a handover of the UE from the source BS to a target BS. This reduces or eliminates performance issues related to using any of these handover techniques independently. For example, using a combination of a conditional handover and a two protocol stack handover, or a combination of a conditional handover and a dual connectivity handover, may improve reliability relative to using the two protocol stack handover or the dual connectivity handover independently. Additionally, or alternatively, and as another example, these combinations may reduce or eliminate handover ping-pongs and/or radio link failures. In addition, this further reduces a latency associated with performing a handover relative to using various types of handover techniques separately.

<FIG> is a diagram illustrating an example <NUM> of performing a combination of handover techniques, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> may include a UE (e.g., UE <NUM>), a source BS (e.g., BS <NUM>) (e.g., to which the UE is connected via a source connection), and a target BS (e.g., BS <NUM>) (e.g., to which the is being handed over from the source BS and/or to which the UE is to be connected via a target connection).

As shown by reference number <NUM>, the source BS may determine that the UE is to perform at least one of a conditional handover, a two protocol stack handover, or a dual connectivity handover. In some aspects, a conditional handover may include a handover where a handover command (e.g., a radio resource configuration (RRC) connection reconfiguration that includes mobility control information) is associated with a condition. For example, when the UE determines that the condition is satisfied, the UE may perform a handover in accordance with the handover command. In some aspects, a two protocol stack handover may include a multi-phase handover where two protocol stacks are used to handover the UE from a source BS to a target BS (e.g., a first protocol stack is used for continued communications with the source BS while a second protocol stack is used for handover of the UE from the source BS to the target BS), and may sometimes be referred to as a dual active protocol stack-based handover. In some aspects, a dual connectivity handover may include a handover where a UE is simultaneously connected to a source BS as a primary BS and to a target BS as a secondary BS, and where the source BS and the target BS communicate with each other to exchange roles (e.g., the source BS becomes the secondary BS and the target BS becomes the primary BS).

In some aspects, the source BS may receive, from the UE, capability information. For example, the capability information may identify a capability of the UE to perform the at least one of the conditional handover, the two protocol stack handover (e.g., a dual active protocol stack-based handover), or the dual connectivity handover. In some aspects, the source BS may determine that the UE is to perform the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover based at least in part on receiving the capability information.

As shown by reference number <NUM>, the source BS may transmit, and the UE may receive, a handover indication. For example, the handover indication may indicate that the UE is to perform the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover. Continuing with the previous example, the handover indication may indicate that the UE is to perform the conditional handover, is to perform the two protocol stack handover, is to perform the dual connectivity handover, is to perform a combination of the conditional handover and the two protocol stack handover, is to perform a combination of the conditional handover and the dual connectivity handover, is to perform a combination of the dual connectivity handover and the two stack protocol handover, and/or the like.

In some aspects, the handover indication may be included in a radio resource control (RRC) connection reconfiguration request. For example, the RRC connection reconfiguration request may be transmitted from the source BS to the UE. In some aspects, the RRC connection reconfiguration request may include a set of conditions that the UE is to use to select a target BS. For example, the UE may select a target BS based at least in part on satisfaction of one or more of the set of conditions, as described elsewhere herein.

In some aspects, the handover indication may be based at least in part on an indication received from a mobility management entity (MME). For example, the indication from the MME may be based at least in part on a type of application associated with the UE, a quality of service level associated with the UE, an access point network (APN) type associated with a subscription profile of the UE, and/or the like.

In some aspects, the source BS may determine a priority (e.g., prioritization) of the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover. For example, the source BS may determine the priority prior to transmitting the handover indication (e.g., the priority may indicate that a particular handover technique, or combination of handover techniques, is to be used rather than another handover technique, or combination of techniques). In some aspects, the source BS may determine the priority based at least in part on the indication from the MME. For example, the indication from the MME may identify particular applications as needing a threshold reliability, may identify the UE as needing a threshold reliability and/or latency (e.g., a quality of service), and/or the like.

In some aspects, the source BS may perform a handover decision. For example, the source BS may perform the handover decision for the UE based at least in part on a measurement report received from the UE and/or prior to transmitting the handover indication. Additionally, or alternatively, the source BS may determine that the UE is to perform the combination of the conditional handover and the two protocol stack handover, or the combination of the conditional handover and the dual connectivity handover. For example, the source BS may determine that the UE is to perform the combination of the conditional handover and the two protocol stack handover, or the combination of the conditional handover and the dual connectivity handover, based at least in part on performing the handover decision (e.g., after performing the handover decision and/or prior to transmitting the handover indication). Additionally, or alternatively, the source BS may perform a respective handover preparation with multiple target BSs, of a set of target BSs. For example, the source BS, based at least in part on determining that the UE is to perform the combination of the conditional handover and the two protocol stack handover, or the combination of the conditional handover and the dual connectivity handover, may perform a first handover preparation with a first target BS and a second handover preparation with a second target BS. For example, the source BS may transmit, to one or more target BSs, information that identifies whether the UE is to perform a combination of the conditional handover and the two protocol stack handover or whether the UE is to perform a combination of the conditional handover and the dual connectivity handover.

As shown by reference number <NUM>, the UE may perform the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover. For example, the UE may perform the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover based at least in part on the handover indication received from the source BS.

In some aspects, the UE may perform a combination of the conditional handover and the two protocol stack handover, or a combination of the conditional handover and the two protocol stack handover, based at least in part on the indication. For example, the UE may perform the conditional handover to select the target BS, and may perform the two protocol stack handover, or the dual connectivity handover, to complete a handover of the UE from the source BS to the target BS (e.g., while a source connection between the UE and the source BS and a target connection between the UE and the target BS are active, where the source BS and the target BS exchange roles, and/or the like).

In some aspects, the UE may perform the conditional handover and not the two protocol stack handover or the dual connectivity handover based at least in part on the indication. For example, the UE may perform the conditional handover from the source BS to the target BS. In some aspects, the UE may perform the two protocol stack handover and not the conditional handover or the dual connectivity handover based at least in part on the indication. For example, the UE may perform the two protocol stack handover from the source BS to the target BS. In some aspects, the UE may perform the dual connectivity handover and not the conditional handover or the two protocol stack handover based at least in part on the indication. For example, the UE may perform the dual connectivity handover from the source BS to the target BS.

In some aspects, the UE may select a target BS prior to performing a handover. For example, and for a conditional handover, the UE may select a target BS from a set of target BSs. Additionally, or alternatively, and as another example, the UE may select a particular target BS based at least in part on a handover decision by the source BS.

Other examples are possible and may differ from what was described with respect to Fig. <NUM>.

<FIG> and <FIG> are diagrams of a call flow <NUM> for performing a combination of handover techniques, in accordance with various aspects of the present disclosure. Specifically, <FIG> and <FIG> show an example of performing a combination of a conditional handover and a two protocol stack handover (e.g., a dual active protocol stack-based handover).

As shown by reference number <NUM>, the source BS may provide a measurement control message to the UE. The measurement control message may indicate for the UE to determine measurement for handover of the UE. In some aspects, the measurement control message may indicate to determine a particular measurement report, such as an A3 measurement report.

As shown by reference number <NUM>, the UE may provide a measurement report to the BS in connection with the measurement control message. For example, the UE may determine measurements for cells that cover the UE. Assume that the target BS is identified based at least in part on the measurements. Assume that the target BS is associated with a threshold measurement value so that the source BS is to configure handover of the UE from the source BS to the target BS. For example, the threshold measurement value may be smaller than a legacy measurement value (e.g., a measurement value for non-low-latency handover), as described in more detail elsewhere herein.

As shown by reference number <NUM>, the source BS may perform a handover decision based at least in part on the measurement report. For example, the source BS may determine that the UE is to be handed over to the target BS based at least in part on the measurement report. As shown by reference number <NUM>, the source BS may provide a handover request to the target BS in connection with performing the handover decision. For example, the handover request may identify the UE and may indicate that the UE is to be handed over to the target BS.

As shown by reference number <NUM>, the source BS may perform a respective handover (HO) preparation with a set of target BSs. For example, and when the UE is to perform a combination of a conditional handover and another handover (e.g., a dual connectivity handover or a two protocol stack handover) the source BS may perform a first HO preparation with a first target BS, may perform a second HO preparation with a second target BS, and so forth. A source BS may perform HO preparation with multiple target BSs simultaneously to reduce an amount of time needed for the HO preparation process. In some aspects, performing a HO preparation may include providing a UE context for the UE to the set of target BSs, causing the set of target BSs to allocate resources (e.g., time frequency resources, bearer configuration, RACH resources, etc.) for a handover of the UE, and/or the like. For example, the source BS may transmit, to one or more target BSs, information that identifies whether the UE is to perform a combination of the conditional handover and the two protocol stack handover or whether the UE is to perform a combination of the conditional handover and the dual connectivity handover.

As shown by reference number <NUM>, the target BS may provide a handover request acknowledgment (ACK) to the source BS. For example, the target BS may provide the handover request ACK to indicate that the target BS accepts the handover of the UE and provides needed HO configuration information.

As shown by reference number <NUM>, the source BS may provide an RRC connection reconfiguration request to the UE. The RRC reconfiguration request may indicate that the UE is to be handed over from the source BS to the target BS. In some aspects, the source BS may provide the RRC connection reconfiguration request to a source protocol stack of the UE.

As shown by reference number <NUM>, the UE (e.g., the source protocol stack of the UE) may continue downlink/uplink data communications (e.g., transfer) with the source BS. For example, the UE may continue to receive downlink data and to transmit uplink data to the source BS. In this way, communications of the UE with the source BS may not be interrupted, thereby reducing latency associated with interruption of communications of the UE during handover.

As shown by reference number <NUM>, the UE may perform parallel RRC processing to configure the target protocol stack (e.g., a second L2/L1 stack) and to acquire the target BS using a second receive antenna of the UE (e.g., Rx2). For example, the UE may configure (e.g., generate, activate, etc.) the target protocol stack to perform the handover. In some aspects, the UE may configure the target protocol stack based at least in part on receiving the RRC reconfiguration request. In this way, the UE may perform RRC processing to configure the handover using the target protocol stack while (e.g., in parallel) maintaining communications with the source BS.

In some aspects, the target protocol stack of the UE may synchronize with the target BS. In some aspects, the target protocol stack of the UE may acquire the target BS.

As shown by reference number <NUM>, after the UE determines conditional HO thresholds are satisfied for a target BS, then the UE may apply HO configuration provided in an RRC connection reconfiguration message and may send a message to the target BS indicating that RRC connection reconfiguration (e.g., handover) of the UE is complete. For example, the second protocol stack may provide the message indicating that RRC connection reconfiguration of the UE is complete.

As shown in <FIG> and by reference number <NUM>, in some aspects, the UE (e.g., the target protocol stack) may provide random access information to the target BS. For example, the random access information may indicate that RRC connection reconfiguration of the UE is complete. Additionally, or alternatively, the UE may send a PDCP status report to the target BS. By providing random access information (e.g., using a random access channel (RACH)), resources of the UE are conserved that would otherwise be used to perform grant-based initial access to the target BS. As shown, the RACH information may be sent to the target BS (e.g., as part of a RACH procedure) before a connection with the source BS is released.

As shown, at this point, the UE may provide uplink data to the target BS. For example, the UE may be associated with an uplink connection with the target BS, and may provide the uplink data to the target BS. In some aspects, the UE may be associated with a single transmit chain. For example, the UE may tune the single transmit chain from the source BS to the target BS to provide the uplink data to the target BS. In this way, the UE conserves resources and reduces latency that would be associated with providing the uplink data to only the source BS, or the source BS and the target BS. In some aspects, the UE may provide the uplink data to the source BS and to the target BS, which improves robustness of the uplink data.

As shown by reference number <NUM>, the target BS may provide a data forwarding notification to the source BS. For example, the data forwarding notification may include an X2 data forwarding notification for an X2 interface between the target BS and the source BS and/or the like. The data forwarding notification may indicate that the source BS is to forward at least a portion of downlink data of the UE to the target BS. For a more detailed description of such data forwarding, refer to <FIG> and <FIG>, below. By configuring data forwarding between the source BS and the target BS, the target BS reduces latency associated with the handover process pursuant to lost or dropped data.

As shown by reference number <NUM>, the source BS may provide sequence number (SN) information (e.g., an SN status transfer) to the target BS. For example, in a subsequent step of this call flow, the source BS may cease allocating downlink PDCP SNs. If the source BS does not coordinate SNs for the downlink data (e.g., PDCP SNs and/or the like), collisions may occur between downlink data of the source BS and downlink data of the target BS. This may increase latency of the handover process and/or lead to dropped traffic.

As shown by reference number <NUM>, the source BS may be associated with a first timer (e.g., timer <NUM>). The first timer may identify a backhaul delay period. For example, the first timer may identify a length of time after which the source BS is to stop providing downlink data to the UE. Additionally, or alternatively, the first timer may identify a length of time after which a PDCP of the source BS is to stop providing downlink data to an RLC layer of the source BS for transmission to the UE. In some aspects, after expiry of the first timer, the source BS may continue to transmit downlink data. For example, the source BS may continue to transmit downlink data until a buffer (e.g., an RLC buffer) of the source BS is cleared. As another example, the source BS may continue to transmit downlink data until a connection with the UE is ended or lost. As yet another example, the target BS may provide an indication to cause the source BS to end the connection.

As shown by reference number <NUM>, the target BS may be associated with a second timer (e.g., timer <NUM>). The second timer may identify a length of time during which the UE may receive downlink data from the source BS and the target BS. For example, the UE may receive redundant data from the source BS and the target BS between the RRC reconfiguration complete message and the SN status transfer message. After the SN status transfer message, the target BS may begin to provide downlink data to the UE. In some aspects, the first timer and/or the second timer may not be used. For example, when backhaul delay of the source BS and the target BS is small (e.g., less than approximately <NUM> to <NUM>), the first timer and/or the second timer may not be used, thereby conserving processor resources.

As shown by reference number <NUM>, the target BS may provide a path switch request to an MME. The path switch request may indicate that a data path (e.g., a main path, a primary path, etc.) of the UE is to be switched from the source BS to the target BS. As shown by reference number <NUM>, the MME may provide a modify bearer request to the S-GW based at least in part on the path switch request to cause the S-GW to switch the data path from the source BS to the target BS.

As shown, the S-GW may switch the data path from the source BS to the target BS. As further shown, the S-GW may provide a downlink end mark to the source BS indicating that the data path has been switched to the target BS. As shown, the source BS may provide the downlink end mark (or information based at least in part on the downlink end mark) to the target BS. At this point, and as shown, the S-GW may provide downlink data for the UE to the target BS, and the target BS may provide the downlink data to the UE (e.g., to the target protocol stack of the UE).

As shown by reference number <NUM>, the S-GW may provide a modify bearer response to the MME in connection with the modify bearer request. As shown by reference number <NUM>, the MME may provide a path switch request acknowledgment (ACK) to the target BS. The path switch request acknowledgment may indicate that the data path has been switched from the source BS to the target BS.

As shown by reference number <NUM>, the target BS may provide, to the UE (e.g., the target protocol stack of the UE), an RRC connection reconfiguration message. The RRC connection reconfiguration message may indicate to release the source protocol stack. As further shown, the UE (e.g., the target protocol stack of the UE) may release the source protocol stack.

As shown by reference number <NUM>, the target BS may provide a message to cause the source BS to release a UE context of the UE (e.g., the source protocol stack). The source BS may release the UE context in connection with the message. Thus, the target BS may cause the source BS to release the context (e.g., and/or a corresponding connection) with the UE. As shown by reference number <NUM>, the UE may provide a message indicating that RRC reconfiguration is complete (e.g., that the release of the source BS is complete). For example, the target protocol stack of the UE may provide the message to indicate that handover to the target BS is complete.

Other examples are possible and may differ from what was described with respect to <FIG> and <FIG>.

<FIG> and <FIG> are diagrams of a call flow <NUM> for performing a combination of handover techniques, in accordance with various aspects of the present disclosure. Specifically, <FIG> and <FIG> show an example of performing a combination of a conditional handover and a dual connectivity handover.

As shown in <FIG>, and by reference number <NUM>, a source eNB (e.g., a source BS) may perform a conditional secondary cell group (SCG) addition decision. For example, the source eNB may determine target eNBs (e.g., target BSs) to include in a set of target eNBs from which the UE can connect to during a dual connectivity handover. As shown by reference numbers <NUM> and <NUM>, the source eNB may perform SCG cell preparation with target eNBs included in the SCG (e.g., target eNB <NUM> and target eNB <NUM>). For example, the source eNB may provide a UE context to the target eNBs and/or may cause the target eNBs to allocate resources for the dual connectivity handover, in a manner similar to that described elsewhere herein.

As shown by reference number <NUM>, the source eNB may provide, to the UE, an RRC reconfiguration message. For example, the RRC reconfiguration message may indicate to the UE to use a combination of the conditional handover and the dual connectivity handover, may identify conditions that the UE is to use to select a target eNB and/or to initiate the dual connectivity handover, and/or the like.

As shown by reference number <NUM>, and by reference number <NUM> in <FIG>, the UE may perform a dual connectivity handover of the UE from the source eNB to a target eNB.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a UE (e.g., UE <NUM> and/or the like) performs operations associated with performing a combination of handover techniques.

As shown in <FIG>, in some aspects, process <NUM> may include receiving, from a source BS, an indication that the UE is to perform a conditional handover from the source BS to a target BS and is to perform at least one of: a two protocol stack handover from the source BS to the target BS, or a dual connectivity handover from the source BS to the target BS (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive, from a source BS, an indication that the UE is to perform a conditional handover from the source BS to a target BS and is to perform at least one of a two protocol stack handover from the source BS to the target BS or a dual connectivity handover from the source BS to the target BS, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include performing the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover based at least in part on the indication (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover based at least in part on the indication, as described above.

In a first aspect, the indication is included in a radio resource control (RRC) connection reconfiguration request from the source BS to the UE, and the RRC connection reconfiguration request further includes a set of conditions that the UE is to use to select the target BS.

In a second aspect, alone or in combination with the first aspect, performing the conditional handover comprises selecting the target BS based at least in part on a condition, of the set of conditions, being satisfied.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes transmitting, to the source BS, capability information that identifies a capability of the UE to perform at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover, and receiving the indication comprises receiving the indication based at least in part on transmitting the capability information.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the indication is based at least in part on another indication from a mobility management entity (MME), and the other indication is based at least in part on at least one of: a type of application associated with the UE, a quality of service level associated with the UE, or an access point network (APN) type associated with a subscription profile of the UE.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the indication is based at least in part on a prioritization of different types of handovers by the source BS.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, performing the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover comprises: performing the conditional handover to select the target BS before releasing the source BS; and performing the two protocol stack handover to complete a handover of the UE from the source BS to the target BS while a source connection between the UE and the source BS and a target connection between the UE and the target BS are active.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, performing the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover comprises: performing the conditional handover to select the target BS; and performing the dual connectivity handover to complete a handover of the UE from the source BS to the target BS.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, performing the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover comprises performing a random access channel (RACH) procedure with the target BS before releasing the source BS.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a source BS, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a source BS (e.g., base station <NUM> and/or the like) performs operations associated with performing a combination of handover techniques.

As shown in <FIG>, in some aspects, process <NUM> may include determining that a UE is to perform a conditional handover from the source BS to a target BS and is to perform at least one of: a two protocol stack handover from the source BS to the target BS, or a dual connectivity handover from the source BS to the target BS (block <NUM>). For example, the source BS (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine that a UE is to perform a conditional handover from the source BS to a target BS and is to perform at least one of a two protocol stack handover from the source BS to the target BS or a dual connectivity handover from the source BS to the target BS, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting, to the UE, an indication that indicates that the UE is to perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover (block <NUM>). For example, the source BS (e.g., using transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit, to the UE, an indication that indicates that the UE is to perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover, as described above.

In a second aspect, alone or in combination with the first aspect, process <NUM> includes receiving, from the UE, capability information that identifies a capability of the UE to perform at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover, and determining that the UE is to perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover comprises determining that the UE is to perform the conditional handover and at least one of the two protocol stack handover or the dual connectivity handover based at least in part on receiving the capability information.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes receiving, from a mobility management entity (MME), another indication, and the other indication is based at least in part on: a type of application associated with the UE, a quality of service level associated with the UE, or an access point network (APN) type associated with a subscription profile of the UE; and the indication is further based at least in part on the other indication.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process <NUM> includes determining a priority of the at least one of the conditional handover, the two protocol stack handover, or the dual connectivity handover based at least in part on the other indication.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the indication indicates that the UE is to perform: a combination of the conditional handover and the two protocol stack handover, or a combination of the conditional handover and the dual connectivity handover.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, process <NUM> includes performing a handover decision for the UE based at least in part on a measurement report received from the UE; determining that the UE is to perform the combination of the conditional handover and the two protocol stack handover or the combination of the conditional handover and the dual connectivity handover based at least in part on performing the handover decision; performing respective handover preparations with multiple target BSs, of a set of target BSs, based at least in part on determining to perform the combination of the conditional handover and the two protocol stack handover or the combination of the conditional handover and the dual connectivity handover; and transmitting the indication to the UE based at least in part on performing the respective handover preparations with the multiple target BSs.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process <NUM> includes transmitting, to the target BS, information that identifies whether the UE is to perform the combination of the conditional handover and the two protocol stack handover or the combination of the conditional handover and the dual connectivity handover.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible aspects. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible aspects includes each dependent claim in combination with every other claim in the claim set.

Claim 1:
A method of wireless communication performed by a user equipment, UE (<NUM>), comprising:
receiving, from a source base station, BS (<NUM>), an indication that the UE (<NUM>) is to perform a conditional handover from the source BS (<NUM>) to a target BS (<NUM>), wherein the conditional handover includes a handover where a handover command is associated with a condition, wherein the indication is included in a radio resource control, RRC, connection reconfiguration request;
preparing a two protocol stack handover from the source BS (<NUM>) to the target BS (<NUM>), wherein the two protocol stack handover is a multi-phase handover, in which the UE (<NUM>) continues downlink/uplink data communications with the source BS (<NUM>) while in parallel performing RRC processing to configure the target protocol stack to perform the handover; and
performing the two protocol stack handover when the UE (<NUM>) determines the condition is satisfied for the target BS (<NUM>), by sending an RRC connection reconfiguration message to the target BS (<NUM>).