Coordinate with the mobility of DAPS

Abstract

A fifth-generation (5G) communication system or a sixth-generation (6G) communication system is provided for supporting higher data rates beyond fourth-generation (4G) communication systems such as Long-Term Evolution (LTE). A method of a Dual Active Protocol Stack (DAPS) for switching a User Equipment (UE) from a source gNB to a target gNB is described. The method includes receiving UE capability information including DAPS capability from the UE, coordinating, by the source gNB, a DAPS handover request for the UE based at least in part on the DAPS capability of the UE, and reconfiguring, by the source gNB, the UE from the source gNB to the target gNB.

Description

Technical Field

[0001] The present disclosure relates to a control network such as a cellular network. More specifically, the present disclosure relates to Dual Active Protocol Stack (DAPS) handover. Background Art

[0002] Considering the development of wireless communication from generation to generation, these technologies have been mainly developed for human-targeted services such as voice calls, multimedia services, and data services. With the commercialization of the fifth-generation (5G) communication system, the number of connected devices is expected to increase exponentially. These will be increasingly connected to the communication network. Examples of connected things may include vehicles, robots, drones, household appliances, displays, smart sensors connected to various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve in various form factors such as augmented reality glasses, virtual reality headsets, and holographic devices. In order to provide various services by connecting hundreds of billions of devices and things in the sixth-generation (6G) era, efforts have been made to develop improved 6G communication systems. For these reasons, the 6G communication system is called the Ultra 5G system.

[0003] The 6G communication system, which is expected to be commercialized around 2030, will have a peak data rate of tera (1000 giga) - level bps and a wireless latency of less than 100 μsec, and will thus be 50 times that of the 5G communication system and have 1 / 10 of its wireless latency.

[0004] In order to achieve such high data rates and ultra - low latencies, it has been considered to implement the 6G communication system in the terahertz band (e.g., 95 GHz to 3 THz band). It is expected that since the path loss and atmospheric absorption in the terahertz band are more severe than those in the mmWave band introduced in 5G, technologies capable of ensuring the signal transmission distance (i.e., coverage) will become more critical. As the main technologies for ensuring coverage, it is necessary to develop radio frequency (RF) components, antennas, new waveforms with better coverage than orthogonal frequency - division multiplexing (OFDM), beamforming, and massive multiple - input multiple - output (MIMO), full - dimensional MIMO (FD - MIMO), array antennas, and multi - antenna transmission technologies such as massive antennas. In addition, new technologies for improving the signal coverage in the terahertz band have been discussed, such as metasurface - based lenses and antennas, orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS).

[0005] In addition, to improve spectral efficiency and overall network performance, the following technologies have been developed for 6G communication systems: full-duplex technology for enabling uplink and downlink transmissions to simultaneously use the same frequency resources, network technologies for integrally leveraging satellites, high-altitude platform stations (HAPS), etc., improved network architectures for supporting mobile base stations, etc. and enabling network operation optimization and automation, etc., dynamic spectrum sharing technology via conflict avoidance based on predicted spectrum usage, the use of artificial intelligence (AI) in wireless communication for improving overall network operation by leveraging AI from the design stage of developing 6G and internalizing end-to-end AI support functions, and next-generation distributed computing technology for overcoming the computing power limitations of user equipment (UE) through ultra-high-performance communication and computing resources (such as mobile edge computing (MEC), cloud, etc.) accessible over the network. In addition, by designing new protocols to be used in 6G communication systems, developing mechanisms for implementing hardware-based secure environments and secure use of data, and developing technologies for maintaining privacy, efforts are continuing to strengthen connectivity between devices, optimize the network, promote the softwareization of network entities, and increase the openness of wireless communication.

[0006] It is expected that the research and development of 6G communication systems in hyper-connectivity (including person-to-machine (P2M) and machine-to-machine (M2M)) will enable the next hyper-connectivity experience. More specifically, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas will be provided through 6G communication systems. In addition, services such as remote surgery, industrial automation, and emergency response for security and reliability enhancement will be provided through 6G communication systems, enabling these technologies to be applied to various fields such as industry, healthcare, automotive, and household appliances.

[0007] The cell handover latency in the fourth-generation (4G) Long-Term Evolution (LTE) system is typically 30 ms to 60 ms. 5G's ultra-reliable, low-latency use cases (such as in the transportation and manufacturing fields) require the cell handover latency to be reduced to 0 ms as much as possible.

[0008] More specifically, the 16th and 17th releases of the 3rd Generation Partnership Project (3GPP) introduced features to support use cases related to smart manufacturing, connected vehicles, power distribution, and even network-controlled drones. To meet these use cases, it is crucial to reduce the handover interruption time or latency between cells in the 5G network.

[0009] Figure 1FIG. 0 schematically depicts a 5G network 1, and in particular, depicts a handover of a UE 100A from a source cell 10A including a first base station (gNodeB) (gNB) 11A across a cell boundary 12AB of the related art to a target cell 10B including a second gNB 11B. During the handover, there is a short period of time (i.e., an interruption time or latency) during which the UE 100A cannot send or receive user data. The mobile interaction time can be defined as the shortest duration supported by the 5G network 1 during the handover.

[0010] The latency occurs because the UE 100A releases the connection to the source cell 10A (i.e., the first gNB 11A) before establishing a link to the target cell 10B (i.e., the second gNB 11B). For example, before the UE 100A starts communicating with the second gNB 11B in the target cell 10B, uplink transmissions ULA and downlink transmissions DLA are completed in the source cell 10A.

[0011] To reduce the latency, DAPS handover (also known as enhanced make-before-break handover) allows the connection to the source cell 10A to remain active to receive and send user data until the UE 100A is able to receive and send user data in the target cell 10B. Therefore, the UE 100A needs to receive and send user data simultaneously in both the source cell 10A and the target cell 10B.

[0012] Therefore, there is a need to improve handover.

[0013] The above information is presented only as background information to assist in understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above may be applied as prior art to the present disclosure. SUMMARY OF THE INVENTION

[0014] TECHNICAL SOLUTION

[0015] Aspects of the present disclosure at least solve the above problems and / or disadvantages, and at least provide the following advantages. Accordingly, one aspect of the present disclosure is to provide a method and network having reduced latency during handover compared to handover of the related art. For example, the objective of the present disclosure is to provide a method and network having a more efficient and / or robust handover compared to handover, such as minimizing complexity and / or reducing latency simultaneously.

[0016] Another aspect of the present disclosure is to provide a method for a dual active protocol stack (DAPS) to switch a user equipment (UE) from a source base station (gNodeB) (gNB) to a target gNB. The method includes the UE indicating UE capability information including DAPS capability to the source gNB, the source gNB and / or the target gNB coordinating a DAPS handover request for the UE at least partially based on the UE's DAPS capability, and the source gNB and / or the target gNB reconfiguring the UE from the source gNB to the target gNB.

[0017] Another aspect of the present disclosure is to provide a network including a UE, a source gNB, and a target gNB. The UE is arranged to indicate UE capability information including DAPS capability to the source gNB, the source gNB and / or the target gNB are arranged to coordinate a DAPS handover request for the UE at least partially based on the UE's DAPS capability, and the source gNB and / or the target gNB are arranged to reconfigure the UE from the source gNB to the target gNB so as to switch the UE from the source gNB to the target gNB.

[0018] Another aspect of the present disclosure is to provide a UE according to the second aspect.

[0019] Another aspect of the present disclosure is to provide a gNB according to the second aspect, such as a source gNB or a target gNB.

[0020] Another aspect of the present disclosure is to provide a method for DAPS (handover of UE from source gNB to target gNB). The method includes the source gNB receiving UE capability information including DAPS capability from the UE, the source gNB coordinating a DAPS handover request for the UE at least partially based on the UE's DAPS capability, and the source gNB reconfiguring the UE from the source gNB to the target gNB.

[0021] Another aspect of the present disclosure is to provide a source gNB according to the fifth aspect.

[0022] According to the present disclosure, a method as set forth in the appended claims is provided. A network is also provided. Other features of the present disclosure will become apparent from the dependent claims and the subsequent description.

[0023] Additional aspects will be set forth in part in the description below, and in part will become apparent from the description, or may be learned by practice of the presented embodiments.

[0024] According to an aspect of the present disclosure, a method for DAPS handover of a UE from a source gNB to a target gNB is provided. The method includes the UE indicating UE capability information including DAPS capability to the source gNB, the source gNB and / or the target gNB coordinating a dual active protocol stack (DAPS) handover request for the UE at least partially based on the UE's DAPS capability, and the source gNB and / or the target gNB reconfiguring the UE from the source gNB to the target gNB.

[0025] Feature 1

[0026] In one example, the source gNB and / or the target gNB coordinating the handover request for the UE includes establishing capability coordination between them.

[0027] In one example, establishing capability coordination between the source gNB and the target gNB includes the source gNB adapting to the target gNB or the target gNB adapting to the source gNB.

[0028] In one example, the target gNB adapting to the source gNB includes the source gNB indicating the source configuration to the target gNB, and the target gNB setting the target configuration at least partially based on the UE capability information and the source configuration, by considering what the source gNB has adopted for the source configuration and using the remaining part of the UE capability for the target configuration.

[0029] In one example, the source gNB adapting to the target gNB includes the target gNB indicating the configuration to be used by it, and the source gNB using the remaining part.

[0030] In one example, the target gNB adapting to the source gNB includes the source gNB providing one or more configuration options to the target gNB, and the target gNB selecting one of the provided configuration options.

[0031] Feature 2

[0032] In one example, reconfiguring the UE from the source gNB to the target gNB involves three reconfiguration messages.

[0033] In one example, reconfiguring the UE from the source gNB to the target gNB includes the source gNB sending a first reconfiguration message to the UE to reduce the UE capabilities required relative to the source gNB.

[0034] In one example, the first reconfiguration message includes a field / bit indicating the latency for the UE to apply the received configuration.

[0035] In one example, reconfiguring the UE from the source gNB to the target gNB includes the source gNB sending a second reconfiguration message to the UE to reconfigure the UE to initiate a DAPS handover.

[0036] In one example, the second reconfiguration message includes an indication of whether to apply DAPS operation, such as a field / bit specifying that the UE should continue to use the source configuration and / or apply DAPS operation.

[0037] In one example, the second reconfiguration message includes a field / bit specifying that the UE should apply a reduced source configuration and / or a target configuration that the UE previously indicated as an option for supporting DAPS.

[0038] In one example, reconfiguring the UE from a source gNB to a target gNB includes sending a third reconfiguration message from the target gNB to the UE for reconfiguring the UE to release the source configuration and reconfiguring the UE to apply the target configuration at least partially based on UE capability information (e.g., using all UE capabilities of the target configuration, such as those including capabilities required for operating the source connection previously).

[0039] In one example, the third reconfiguration message includes a field / bit specifying that the UE will release the source configuration.

[0040] Feature 3

[0041] In one example, the method includes the source gNB initiating a fallback to a normal or fallback to mobile broadband (MBB) handover.

[0042] Feature 4

[0043] In one example, the DAPS capability defines the supported configurations relative to the current or a specific configuration.

[0044] In one example, the DAPS capability is included in a ReconfigurationComplete message or a multi-radio (MR) message.

[0045] In one example, the MR message indicates the DAPS capability relative to the current source configuration and / or for the target for which the MR was triggered.

[0046] Feature 5

[0047] In one example, the DAPS capability includes per-UE capability.

[0048] In one example, the DAPS capability includes per-BC capability, e.g., where the per-BC UE capability includes a DAPS capability that indicates DAPS support or that the BC supports a DAPS capability different from the per-UE DAPS capability.

[0049] In one example, the per-BC DAPS capability includes an FSC indicating the DAPS capability.

[0050] In one example, the UE capability information includes a mode for time-division multiplexing (TDM) operation, such as where the UE is and / or capable of non-carrier aggregation / double connection (CA / DC).

[0051] A second aspect provides a network including a UE, a source gNB, and a target gNB, where:

[0052] The UE is arranged to indicate to the source gNB UE capability information including DAPS capability,

[0053] The source gNB and / or the target gNB are arranged to coordinate a dual active protocol stack DAPS handover request for the UE at least partially based on the DAPS capability of the UE, and

[0054] The source gNB and / or the target gNB are arranged to reconfigure the UE from the source gNB to the target gNB, thereby handing over the UE from the source gNB to the target gNB.

[0055] The network, the source gNB, and / or the target gNB can be as described regarding the first aspect and can be arranged to, for example, be adapted to implement any method steps described regarding the first aspect.

[0056] A third aspect provides a UE according to the second aspect.

[0057] A fourth aspect provides a gNB, such as a source gNB or a target gNB, according to the second aspect.

[0058] Definition

[0059] Throughout this specification, the term "comprising" or "including" means including the specified component(s), but not excluding the presence of other components. The term "consisting essentially of" or "consisting essentially of" means including the specified component, but excluding other components, except for materials as impurities, materials that are inevitable as a result of the process for providing the component, and components added for purposes other than achieving the technical effects of the present disclosure, such as colorants, etc.

[0060] The term "consisting of" or "consisting of" means including the specified component, but excluding other components.

[0061] At an appropriate time, depending on the context, the use of the term "including" or "comprising" can also be understood to mean including "consisting essentially of" or "consisting essentially of", and can also be understood to mean including "consisting of" or "consisting of".

[0062] Where appropriate, and particularly in the combinations set forth in the appended claims, the alternative features set forth herein may be used alone or in combination with one another. As set forth herein, if appropriate, the alternative features of each aspect or embodiment of the present disclosure are also applicable to all other aspects or embodiments of the present disclosure. In other words, those skilled in the art reading this specification should consider the alternative features of each aspect or embodiment of the present disclosure to be interchangeable and combinable between different aspects and embodiments.

[0063] From the following detailed description of various embodiments of the present disclosure, which is disclosed in conjunction with the accompanying drawings, other aspects, advantages, and salient features of the present disclosure will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] From the following description in conjunction with the accompanying drawings, the above and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent, wherein:

[0065] Figure 1 A network according to the related art is schematically depicted.

[0066] Figure 2 A network according to an embodiment of the present disclosure is schematically depicted.

[0067] Figure 3 A method according to an embodiment of the present disclosure is schematically depicted.

[0068] Figure 4 The method according to an embodiment of the present disclosure is more schematically depicted in detail Figure 3 thereof;

[0069] Figure 5 The method according to an embodiment of the present disclosure is more schematically depicted in detail Figure 3 thereof;

[0070] Figure 6 The method according to an embodiment of the present disclosure is more schematically depicted in detail Figure 3 thereof; and

[0071] Figure 7 A flowchart is schematically depicted, which shows a method of a dual active protocol stack (DAPS) for switching a user equipment (UE) from a source base station (gNodeB) (gNB) to a target gNB according to an embodiment of the present disclosure.

[0072] Throughout the drawings, it should be noted that the same reference numerals are used to depict the same or similar elements, features, and structures. DETAILED DESCRIPTION

[0073] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are only considered exemplary. Thus, those of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and structures may be omitted for clarity and conciseness.

[0074] The terms and words used in the following description and claims are not limited to their bibliographical meanings, but are used only by the inventors to enable a clear and consistent understanding of the present disclosure. Thus, it will be apparent to those skilled in the art that the following description of the various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0075] It should be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

[0076] Network

[0077] Figure 1 Network 1 according to the related art is schematically depicted. Figure 2 Network 2 according to an embodiment of the present disclosure is schematically depicted.

[0078] Reference Figure 1 and Figure 2 , Network 2 is generally as described with respect to Network 1, and like reference numerals indicate like features.

[0079] In this example, Network 2 includes a User Equipment (UE) 100A, a source base station gNodeB (gNB) 11A, and a target gNB 11B, where the UE 100A is arranged to indicate UE capability information including Dual Active Protocol Stack (DAPS) capability to the source gNB 11A, and the source gNB 11A and / or the target gNB 11B are arranged to coordinate a (DAPS) handover request for the UE 100A at least partially based on the DAPS capability of the UE 100A, and the source gNB 11A and / or the target gNB 11B are arranged to reconfigure the UE 100A from the source gNB 11A to the target gNB 11B, thereby handing over the UE 100A from the source gNB 11A to the target gNB 11B.

[0080] It should be understood that Network 2 includes Long Term Evolution (LTE), NR, or any other Radio Access Technology (RAT).

[0081] In short, after receiving a handover request, Network 2 provides for continuous transmission and reception of user data of UE 100A in source cell 10A by having UE 100A receive user data from source cell 10A and target cell 10B simultaneously during the handover.

[0082] More specifically, when receiving a request to perform a DAPS handover (i.e., a handover with reduced interruption time) from Network 2 (e.g., from source cell 10A), UE 100A continues to transmit and receive user data in source cell 10A. A new connection to target cell 10B is established by UE 100A, and UE 100A performs synchronization and random access in target cell 10B. UE 100A establishes a new user plane protocol stack for target cell 10B, including PHY (Physical), MAC (Media Access Control), and RLC (Radio Link Control) layers, while also keeping the source user plane protocol stack active for transmission and reception of user data in source cell 10A.

[0083] Thus, UE 100A can receive user data from source cell 10A and target cell 10B simultaneously. Accordingly, the Packet Data Convergence Protocol (PDCP) layer is reconfigured to a common PDCP entity for the source and target user plane protocol stacks. During the handover process, PDCP SN (Sequence Number) continuity is maintained to ensure in-order delivery of user data, e.g., provided by reordering and implicit functions that can be provided in the common PDCP entity. Encryption and / or decryption and header compression and / or decompression can be handled separately by the common PDCP entity, e.g., according to the source or destination of uplink or downlink data packets. Typically, the PDCP entity implements separate security contexts for the source and target.

[0084] User data received from the 5G Core is forwarded from source gNB 11A to target gNB 11B while user data is sent from source gNB 11A to UE 100A, such that when UE 100A is ready to receive user data in target cell 10B, target gNB 11B can send the user data to UE 100A.

[0085] In other words, DAPS handover (HO) is a handover process that maintains the connection to source gNB 11A after reception of the RRC message for handover and until the source cell is released after successful random access to target gNB 11B.

[0086] Before successful RACH (UL transition) in the target, when receiving a DAPS HO command, UE 100A maintains DL reception and UL transmission of user data with source gNB 11A.

[0087] At some time after receiving the DAPS HO command, the UE will, as in traditional HO, send a stop using the source connection for UL and switch to using the target connection (i.e., to the target gNB 11B).

[0088] Upon receiving the DAPS HO command, UE 100A will start using the target connection for DL reception (i.e., to the target gNB 11B) and continue to receive DL from the source gNB 11A. The UE will continue DL reception until the release of resources.

[0089] In case of HO failure, if the source link is valid, UE 100A can use the source link for recovery instead of reconstruction.

[0090] In LTE, the term handover is typically used for the process employed for a change of the PCell. The same process can also be used for other scenarios, including those without a change of mobility / cell.

[0091] In contrast, in NR, the term "handover" is generally not used. Instead, the term "reconfiguration with sync (and security refresh)" is typically used for the process of a change of the PCell. This reconfiguration process can again be used for other scenarios, including those not involving mobility. For mobility, the term PCell change is typically used. However, as an exception, the term "handover" is used for DAPS-related scenarios, although it also involves a change of the PCell.

[0092] The reconfiguration with sync is described in GPP Technical Specification (TS) 38.331 version 15.2.1 Release 15, European Telecommunications Standards Institute (ETSI) TS 138 331 V15.2.1 (2018-06), and is hereby incorporated by reference in its entirety in Section 5.3.5.5.2. This process is used when there is mobility (i.e., when there is a change of the PCell), and in such a case, any SCell that can be configured starts in a deactivated state.

[0093] During DAPS HO, it may not seem necessary to use SCell for the target connection. However, within the source, if supported by the UE, it may be useful to continue the use of (some) SCell, i.e., operate the same as before DAPS scheduled via the source PCell.

[0094] During DAPS HO, it seems possible to configure cells in the same frequency band for the source and the target (intra-band CA). Given the above, this is mainly related to the PCell.

[0095] MR-DC is described in 3rd Generation Partnership Project (3GPP) TS 28.540 version 15.1.0 Release 15 8ETSI TS128 540V15.1.0 (2019-04), which is incorporated herein by reference in its entirety. The MR-DC mechanism includes: coordination of UE capabilities such as band combinations and feature sets, UE Tx power, measurements, physical downlink control channel (PDCCH) blind detection, robust header compression (ROHC), configuration alignment (such as discontinuous reception (DRX)), power headroom reporting (PHR), and each node configures the UE based on the results of the interaction between nodes.

[0096] Generally, UE capability signaling and the corresponding coordination are complex, so similar DAPS-specific signaling should be avoided.

[0097] It should be understood that with the arrangement as described in accordance with the second aspect, the UE, source gNB, and / or target gNB are adapted accordingly, for example, including instructions that, when run on a processor having a memory therein, implement the method as described with respect to the first aspect.

[0098] Method

[0099] Figure 3 A method applicable to LTE and NR according to an embodiment of the present disclosure is schematically depicted.

[0100] Reference Figure 3 , the method is a DAPS handover of the UE from the source gNB to the target gNB. The method includes the UE indicating UE capability information including DAPS capability to the source gNB, the source gNB and / or the target gNB coordinating a dual-active protocol stack DAPS handover request for the UE at least partially based on the UE's DAPS capability, and the source gNB and / or the target gNB reconfiguring the UE from the source gNB to the target gNB.

[0101] It should be understood that during DAPS, the UE operates both the source connection to the source gNB and the target connection to the target gNB simultaneously, although the target gNB may be the same as the source gNB (e.g., serving different source and target PCells, such as for the case of in-gNB mobility). Generally, the UE has limited capabilities, e.g., regarding the number of cells that can be configured or the aggregated bandwidth. During DAPS, the first part of the UE capabilities will be used for the source connection and the second part for the target connection in order to limit or even eliminate service interruptions. For example, the UE capabilities will be split or divided between the source and target connections. This means that during DAPS, in order to account for the aforementioned UE capability limitations, both the source connection and the target connection must adopt a slightly reduced configuration (i.e., relative to the full configuration that would be used for only the source connection before handover or only the target connection after handover).

[0102] It should be understood that by coordinating the DAPS handover request, the source gNB and the target gNB interact in order to ensure that the source configuration and the target configuration are set in a way that takes into account the UE capabilities.

[0103] During DAPS, the UE 100A temporarily applies a reduced configuration towards the source node 11A and the target gNB 11B. Some of the main capabilities to consider for the split between the source and target connections include SCell / BC, baseband / feature set including MIMO, bandwidth, RRC signaling between the network and the UE 100A to be avoided / limited for this temporary configuration, and / or during DAPS, the UE100A transmits data only via the source node 11A. I.e., an equal split may not be the best.

[0104] The method according to the first aspect involves one or more of the following:

[0105] UE capabilities (features 4, 5, and 1): Indicating what the UE supports during DAPS operation.

[0106] The network needs to have sufficient knowledge to account for the UE capabilities or avoid interoperability issues due to not considering the UE capabilities;

[0107] Since DAPS involves short durations, it would be desirable to not change / limit the change of UE capabilities, e.g., by using parameters like overheating assistance.

[0108] Configuration (feature 2): The network can adopt the current available triple of RRC reconfiguration messages towards the UE as well as L2 / L1 signaling.

[0109] One reconfiguration message for reducing the source configuration, another for performing the DAPS handover, and a last one for transitioning to the full target configuration.

[0110] Fallback: When needed, e.g., when capabilities are not taken into account, the source can initiate a fallback to normal HO.

[0111] UE behavior can be defined to handle cases where the network does not take UE capabilities into account (e.g., autonomous deactivation / release of SCell).

[0112] In general, the preference is to avoid such situations (considered as incorrect network behavior).

[0113] More specifically, the method according to the first aspect covers one or more of the following:

[0114] UE capability signaling during the DAPS period (features 4, 5):

[0115] The UE provides capabilities related to the current / specific configuration and may do so in response, e.g., in a Measurement Report (MR) message or a ReconfigurationComplete message;

[0116] In the MR message, the UE can indicate the required reduction of the source configuration (if any) to enable DAPS with the target PCell for which the MR is generated.

[0117] Inter-node negotiation during DAPS HO preparation to agree on reconfiguring the UE's capability split / reduction according to its UE capabilities (feature 1):

[0118] As an option, the source can provide multiple options for the target to choose from, or

[0119] Optionally, the source can propose one option.

[0120] Use of configured triples (feature 2):

[0121] Fallback to normal or REL-14 MBB operation, e.g., if the target does not (properly) support DAPS, e.g., not taking UE capabilities into account;

[0122] Indicate in the reconfiguration before DAPS HO that the use of the included reduced source configuration should be deferred until DAPS HO;

[0123] Indicate in DAPS HO to continue source operation;

[0124] Indicate in DAPS HO to apply the reduced source and / or target configuration previously proposed by the UE, e.g., in the MR message;

[0125] Indication in the first reconfiguration after DAPS HO stops DAPS operation / source transceiver / releases the source configuration.

[0126] Further signaling details, namely the temporary reduction and the configuration of the relevant UE capabilities.

[0127] Turning again Figure 3 , which schematically depicts a method applicable to LTE and NR according to an embodiment.

[0128] Legend:

[0129] DAPS: Dual Active Protocol Stack period, i.e., there is transceiver in both the source and the target

[0130] srcD: Reduced source configuration used during the DAPS period

[0131] srcD: Reduced target configuration used during the DAPS period

[0132] >: Field

[0133] >>: Sub-field (i.e., hierarchical field)

[0134] It should be understood that the field and the sub-field can optionally be implemented without layering, i.e., as a field.

[0135] In operation 1, the method includes the UE indicating UE capability information including DAPS capability to the source gNB (S-gNB). More specifically, the UE sends a UECapabilityInformation message including a DAPS capability field to the source gNB.

[0136] For example, in operation 1, the UE indicates the capability to detail what it can support during DAPS operation. The goal is to limit signaling changes, but sufficient to enable the network to set the configuration in a way that takes into account the UE capabilities and avoids interoperability issues (when using / according to feature 5).

[0137] In operation 2, the method includes reporting measurement report information from the UE to the source gNB together with DAPS capability and configuration assistance (when using / according to feature 4). More specifically, the UE sends a measurement report message including a new sub-field DAPS capability / configuration assistance to the source gNB.

[0138] In operation 3, the method includes the source gNB requesting a handover request for the UE including the UE capabilities received from the UE, optionally together with a first DAPS configuration option and / or a second DAPS configuration option (when negotiating UE capability splitting according to feature 1) from the source gNB to the target gNB (T-gNB). More specifically, the source gNB sends a handover request message including a UE capability field and new fields daps-ConfigOption1 and daps-ConfigOption2 to the target gNB.

[0139] At operation 4, the method includes, in response to a received handover request, confirming a handover request confirmation including a selected DAPS configuration option and possible secondary cell group (SCG) reconfiguration information from the target gNB to the source gNB (again according to feature 1). More specifically, in response to a received handover request message, the target gNB sends a handover request confirmation message to the source gNB including an SCG reconfiguration field and a new subfield daps-ConfigSelected.

[0140] Thus, operations 3 and 4 include the source gNB and / or the target gNB coordinating a dual active protocol stack DAPS handover request for the UE, at least partially based on the UE's DAPS capabilities.

[0141] For example, at operations 3 and 4, the source and the target may negotiate how to split the UE capabilities for setting the source and target configurations. Some notes on this negotiation:

[0142] - The nodes have more or less equal rights, i.e., there is no clear master / slave;

[0143] - The goal is to conduct a one-step negotiation, i.e., there are no additional inter-node messages (i.e., maintaining the existing sequence);

[0144] - There can be different negotiation options. For example, the source can provide multiple DAPS configuration options for the target to choose from, e.g., reflecting different split ratios;

[0145] That is, a moderate target can choose the first option, while a greedy target can choose the second option.

[0146] - If needed, the source can initiate a fallback to normal HO, e.g., if the target does not (properly) support DAPS regardless of capabilities;

[0147] Different fallback options can be used: a) fallback to normal HO, or b) fallback to Rel-14 MBB (for LTE and also possibly for NR).

[0148] In one example, the source gNB and / or the target gNB coordinating a handover request for the UE includes establishing an inter-node capability coordination (i.e., splitting), e.g., by negotiating the inter-node capability coordination and / or by the source gNB or the target gNB defining (i.e., delegating or imposing) the configuration.

[0149] In one example, establishing the capability coordination includes equal splitting (i.e., the nodes have more or less equal rights, i.e., there is no clear master / slave).

[0150] In one example, establishing the capability coordination includes a one-step negotiation.

[0151] In one example, establishing capability coordination between a source gNB and a target gNB includes the source gNB adapting to the target gNB or the target gNB adapting to the source gNB. In one example, establishing capability coordination between a source gNB and a target gNB includes mutual adaptation. For example, the source may provide one or more configuration options to the target such that the target adapts the source according to the selected configuration option, and the source in turn adapts according to the configuration option selected by the target (i.e., the source adapts the remaining part not selected by the target).

[0152] In one example, the target gNB adapting the source gNB includes the source gNB indicating the source configuration to the target gNB, and the target gNB setting the target configuration at least partially based on UE capability information and the source configuration by taking the remaining part of the UE capabilities for the target configuration considering what the source gNB has adopted for the source configuration.

[0153] In one example, the source gNB adapting the target gNB includes the target gNB indicating the configuration to be used by it, and the source gNB using the remaining part.

[0154] In one example, the target gNB adapting the source gNB includes the source gNB providing one or more configuration options to the target gNB, and the target gNB selecting one of the provided configuration options.

[0155] In one example, establishing capability coordination includes the source gNB providing one or more configuration options to the target gNB, and the target gNB selecting one of the provided configuration options.

[0156] In one example, the method includes reconfiguring the UE, the source gNB, and / or the target gNB.

[0157] In operation 5, the method includes sending a first reconfiguration message from the source gNB to the UE, the first reconfiguration message including the source configuration during DAPS together with a field indicating that the UE delays applying such reduced source configuration until DAPS. More specifically, the source gNB sends a first reconfiguration message including a sourceConfigDuringDAPS field and a new field delayConfigUntilDAPS to the UE.

[0158] In operation 6, the method includes sending a reconfiguration complete message from the UE to the source gNB in response to the received first reconfiguration message when the UE has completed reconfiguration according to the received first reconfiguration message. More specifically, in response to the received first reconfiguration message, the UE sends a first reconfiguration complete message to the source gNB.

[0159] Thus, operations 5 and 6 include reconfiguring the UE from a source gNB to a target gNB, including sending, from the source gNB to the UE, a first reconfiguration message for reducing the UE capabilities required with respect to the source gNB (i.e., with respect to the source set). It should be understood that the UE capabilities required for the source connection are reduced such that sufficient UE capabilities are available for simultaneously operating the target connection.

[0160] In one example, the first reconfiguration message includes a field / bit indicating a delay for the UE to apply the received configuration.

[0161] For example, in operations 5 and 6, the source uses the first reconfiguration message (Reconfig1) to reduce the source configuration required for DAPS. This can be performed during HO preparation, unless the reduced source configuration depends on what the target selects (e.g., when, as part of the negotiation during handover preparation, the source provides multiple UE capability split options, leaving the target free to choose what).

[0162] In operation 7, the method includes sending, from the source gNB to the UE, a second reconfiguration message that includes a target configuration to be used during DAPS together with a field specifying that the UE continues with the source configuration. More specifically, the source gNB sends a second reconfiguration message to the source UE that includes a targetConfigDuringDAPS field and a new field continueSourceConfig.

[0163] In operation 8, the method includes sending, in response to the received second reconfiguration message, a reconfiguration complete message from the UE to the target gNB when the UE has completed reconfiguration according to the received second reconfiguration message. More specifically, in response to the received second reconfiguration message, the UE sends a second reconfiguration complete message to the target gNB.

[0164] Thus, operations 7 and 8 include reconfiguring the UE from a source gNB to a target gNB, including sending, from the source gNB to the UE, a second reconfiguration message for reconfiguring the UE to initiate a DAPS handover.

[0165] In one example, the second reconfiguration message includes an indication of whether to apply DAPS operations, such as a field / bit specifying that the UE should continue to use the source configuration and / or apply DAPS operations.

[0166] In one example, the second reconfiguration message includes a field / bit specifying that the UE should apply a reduced source configuration and / or a target configuration that the UE previously indicated as an option for supporting DAPS. For example, this field / bit can be included when using additional and / or alternative mechanisms for indicating DAPS, as described with respect to Feature 4.

[0167] For example, in operations 7 and 8, a second reconfiguration message (Reconfig2) is used to initiate ReconfigWithSync using DAPS.

[0168] In operation 9, the method includes sending a third reconfiguration message from the target gNB to the UE, the third reconfiguration message including the target configuration after DAPS along with a field / bit indicating to the UE to release the source configuration and stop DAPS. More specifically, the target gNB sends a third reconfiguration message to the UE including a targetConfigAfterDAPS field and a new field stopDAPS / release source.

[0169] In operation 10, the method includes sending a reconfiguration complete message from the UE to the target gNB in response to the received third reconfiguration message when the UE has completed reconfiguration according to the received third reconfiguration message. More specifically, in response to the received third reconfiguration message, the UE sends a ReconfigurationComplete message to the target gNB.

[0170] Thus, operations 9 and 10 include reconfiguring the UE, including sending a third reconfiguration message from the target gNB to the UE to reconfigure the UE to release the source configuration and reconfigure the UE to apply the target configuration at least partially based on UE capability (e.g., full UE capability such as including UE capabilities previously required for operating the source connection) information.

[0171] For example, in operations 9 and 10, a third reconfiguration message (Reconfig3) is used to apply the full configuration after DAPS and potentially stop DAPS / release the source configuration / connection:

[0172] - Additional triggers can be defined to transition to the full target configuration / stop DAPS / release the source, e.g., when there are no RRC messages but L2 commands are used to transition to the full target configuration;

[0173] - The transition / release can be performed upon receipt of authorization.

[0174] It should be understood that outside of DAPS, conventional / non-reduced configurations are used in the source gNB or the target gNB.

[0175] Five features related to DAPS HO (Feature 1 to Feature 5) described herein can be applied individually or in combination.

[0176] Feature 1

[0177] Feature 1 involves coordination / negotiation between the source node and the target node regarding UE capabilities to ensure that the source and target set configurations together do not exclude UE capability limitations. That is, the two nodes will have to share UE capabilities and agree on how to split them.

[0178] In one example, the handover request for the UE coordinated by the source gNB and / or the target gNB includes establishing capability coordination between them.

[0179] In one example, establishing capability coordination between the source gNB and the target gNB includes the source gNB adapting to the target gNB or the target gNB adapting to the source gNB. For example, the coordination between the source node and the target node regarding capability coordination can be based on alternatives including the following:

[0180] Option A: The source node adapts to the target node (the target is king)

[0181] In one example, the source gNB adapting to the target gNB includes the target gNB indicating the configuration to be used by it, and the source gNB using the remainder (i.e., the resources not used by the target node).

[0182] HV>The following applies to Method C, where the source provides some options for the target to choose from. For Option A, I suggest the following:

[0183] Option A may introduce additional latency as additional interaction steps may be required. This is because the source configuration selected at the end of the first step will be used as the baseline for the target configuration. In addition, during DAPS, most of the data may be carried by the source, so it seems more desirable for the source to have more say in the decision-making.

[0184] Option B: The source node is king or the target node adapts to the source node

[0185] In one example, the target gNB adapting to the source gNB includes the source gNB indicating the source configuration to the target gNB, and the target gNB setting the target configuration at least partially based on the UE capability information and the source configuration, by taking into account what the source gNB has done for the source configuration and using the remainder of the UE capabilities for the target configuration.

[0186] Compared with Option A, Option B is relatively simpler and involves relatively fewer standard changes. For example, when it gives more decision-making power to the node that can transmit most of the data during DAPS.

[0187] In one example, adapting the source gNB by the target gNB includes the source node indicating the configuration used by it, such as a reduced source configuration, and the target node using the remainder (i.e., the resources not used by the source node). Generally, a UE can support a limited number of serving cells or a limited total aggregated bandwidth (BW). For example, if the UE supports a total aggregated BW of 300, and if the source gNB selects an aggregated BW of 200, the remainder remaining for the target gNB is an aggregated BW of 100.

[0188] Option C: Hybrid

[0189] This option includes some hybridization (hybridized with Option A to make the target king). It will cover cases where the source provides multiple options (otherwise the same as Option B).

[0190] In one example, the method includes the source node restricting the freedom of the target node, such as by providing one or more (i.e., single or multiple) configuration restriction options, and optionally, the target node selecting a configuration restriction option therefrom, i.e., each option reflects a different UE capability split or coordination between the source and target configurations. In one example, the configuration restriction options are prioritized (i.e., provided in order of preference).

[0191] In one example, adapting the source gNB by the target gNB includes the source gNB providing one or more configuration options to the target gNB, and the target gNB selecting one of the provided configuration options.

[0192] For example, while Option C provides a relatively more balanced decision between the source gNB and the target gNB, Option C is relatively more complex and involves relatively more standard changes.

[0193] More specifically, Feature 1 may relate to inter-node negotiation regarding UE capability coordination / splitting. For example, Feature 1 may relate to UE capability sharing. For Option B, the source node is king, i.e., there is no negotiation, but the source node indicates the (reduced) configuration it will use during DAPS operation, and the target node can use the remainder (see Option B above). That is, the source indicates and the target can only set the target configuration according to the remainder of the UE capabilities (a single option provided by the source).

[0194] Figure 4 is schematically depicted in more detail according to an embodiment of the present disclosure Figure 3 of the method. Figure 5 is schematically depicted in more detail according to an embodiment of the present disclosure Figure 3 of the method. More specifically, Figure 5 relates to inter-node interaction.

[0195] Referring to Figure 3 and Figure 5, in operation 1 ( Figure 3 operation 3 of), the method includes a source gNB requesting a handover request from a target gNB.

[0196] In operation 2 ( Figure 3 operation 4 of), the method includes a target gNB confirming the handover request confirmation to the source gNB.

[0197] More specifically, as previously mentioned, the options for inter-node negotiation typically include signaling options based on existing HO preparation sequences and / or each node decides on the configuration details it controls, but the nodes negotiate on the UE capability split used during DAPS.

[0198] As previously mentioned, option A involves the source node adapting to the target node, where the target node is king, i.e., the source node selects from the remainder of the target node such that the target node can choose anything it likes and the source node will have to adjust (the source node can indicate what it prefers to use).

[0199] As previously mentioned, option B involves the source node restricting the freedom of the target node, as Figure 5 schematically shown. For example, the source node decides such that the source node is king, i.e., the target node selects from the remainder of the source node. In this example, the source node indicates the temporary configuration it will use and the target node can select from the remainder.

[0200] More specifically, the options for inter-node negotiation include:

[0201] Generally

[0202] Signaling options based on existing HO preparation sequences;

[0203] Each node decides on the details of the configuration it controls, but the nodes negotiate on the split.

[0204] Options:

[0205] Source adapts to target:

[0206] The target is king, i.e., the source selects from the remainder of the target.

[0207] The target can choose anything it likes and the source will have to adjust (the source can indicate what it prefers to use).

[0208] The source restricts the freedom of the target (as Figure 3 shown).

[0209] The source provides options that the target can choose from, possibly including an indication of the source preferences.

[0210] The source decides:

[0211] The source is the king, that is, the target is selected from the remaining part of the source.

[0212] The source indicates the temporary configuration it will use, and the target can be selected from the remaining part.

[0213] For example, if the target does not support DAPS or generates a target configuration that does not consider the UE capabilities together with the source configuration, the source can initiate a fallback.

[0214] The source may know the capabilities of the target (e.g., OAM), or may infer from the content of the handover request Ack that it is not supported;

[0215] Either fallback to a regular HO or fallback to Rel-14 MBB.

[0216] Feature 2

[0217] Feature 2 relates to the normal process (i.e., successful completion of DAPS HO, i.e., without failure). Specifically, a triple of reconfiguration messages is used during DAPS HO.

[0218] In this example, reconfiguring the UE from the source gNB to the target gNB involves three reconfiguration messages / processes. It should be understood that the triple or the three reconfiguration messages / processes are processed serially (or concatenated) by the UE, i.e., serial reconfiguration. In this way, the serial messages / processes can be sent / implemented conditionally or in response, e.g., based on the success of the previous message / process, and each message / process can handle a specific part of the reconfiguration, thus improving robustness. For example, the method of the three messages is efficient, thus improving handover by reducing latency. In addition, the three-message method is relatively simple and involves very limited changes to the standard. On the contrary, relatively more complex reconfiguration processes (such as combining the first reconfiguration message and the second reconfiguration message or the second reconfiguration message and the third reconfiguration message) require substantial changes to the standard, and the reduction in latency may be more limited.

[0219] During DAPS HO, the UE has a connection with the node controlling the source PCell, which is called the source connection (of the UE). The UE also has a connection with the node controlling the target PCell, which is called the target connection.

[0220] In short, the first reconfiguration message is used to modify the source configuration of the UE to a reduced configuration to enable DAPS operation with the target node (given the UE capabilities). The second reconfiguration message is used to provide the target configuration and instruct the UE to perform DAPS HO. The reconfiguration message may include a field indicating that the UE should continue with the source operation (i.e., perform DAPS instead of a regular HO). The third reconfiguration message includes fields indicating the stop of DAPS operation / source transceiver / release of the source configuration and possibly modifying the target configuration to fully utilize the UE capabilities (i.e., there is no longer a need to split the UE capabilities between the source and target connections).

[0221] In one example, the method includes a general process that includes using a triplet of reconfiguration messages (i.e., a triple reconfiguration message, and thus three reconfiguration messages).

[0222] In one example, reconfiguring the UE from a source gNB to a target gNB includes sending a first reconfiguration message from the source gNB to the UE for reducing the UE capabilities required with respect to the source gNB, e.g., for reducing the UE capabilities required to operate the source set, such that sufficient UE capabilities are available to operate the target connection simultaneously.

[0223] In one example, the first reconfiguration message includes a field / bit indicating the delay in applying the received configuration by the UE.

[0224] In one example, the first reconfiguration message includes an instruction to modify the source configuration of the source node to a reduced configuration for enabling, e.g., considering the UE capabilities, DAPS operation with the target node. In one example, the first message includes a field indicating that the application of the reconfiguration will be delayed until the start of DAPS HO.

[0225] In one example, the second reconfiguration message includes an instruction to provide the target configuration and / or perform DAPS HO. In one example, the second message includes a field indicating that the UE should continue to use the source configuration to apply DAPS operation.

[0226] In one example, the third reconfiguration message includes fields indicating the stop of DAPS operation, source transceiver (i.e., transmit and / or receive), and / or release of the source configuration.

[0227] Figure 4 is schematically depicted in more detail Figure 3 of the method. More specifically, Figure 4 is schematically depicted a triple of reconfiguration messages (i.e., a reconfiguration triple) used at DAPS HO according to an embodiment.

[0228] Generally:

[0229] Option 1: Serial operation: After successful completion of the source reconfiguration, initiate DAPS HO.

[0230] Option 2: Parallel: The reduction of the source configuration is initiated together with DAPS HO (similar to SMC and initial reconfiguration), i.e., the network signals DAPS HO together with the source reconfiguration, rather than only after completion of the source reconfiguration.

[0231] Note that Reconfiguration is used to change the PCell / perform handover, signaling the target configuration by indicating the change compared to the source configuration (i.e., the delta). The source configuration used as the baseline for the Reconfiguration that commands the DAPS handover is different for the first two options. For Option 1, the reduced source configuration is the baseline for the delta (i.e., the configuration resulting after the source reconfiguration), while for Option 2, the original source configuration is the baseline.

[0232] There are two reconfiguration processes:

[0233] A: Change the source configuration to adopt a lower sharing of UE capabilities, so there is a reasonable remainder of the target configuration; and B: Initiate DAPS handover.

[0234] In the case of Option 1, when the UE initiates process B, the network knows that the UE has completed process A. This is relevant because during handover preparation, the source node provides the current configuration to the target node. The target node indicates the target configuration by signaling the change compared to the UE's current source configuration (as received from the source node during handover preparation).

[0235] In the case of Option 2: During DAPS HO preparation, it is not clear what configuration the source node provides to the target node. In this paper, it is assumed that this may be the configuration before process A, i.e., not yet the reduced source configuration.

[0236] In operation 5, the method includes sending a first reconfiguration message Rc1 from the source gNB to the UE for reducing the source configuration of the UE. In this example, the first reconfiguration message Rc1 includes a field / bit indicating that the UE should delay applying the received configuration, i.e., until it applies DAPS operation.

[0237] At operation 7, in this example, the method includes sending a second reconfiguration message Rc2 from the source gNB to the UE for reconfiguring the UE to synchronize with DAPS. In this example, the second reconfiguration message Rc2 includes fields / bits indicating that the UE should continue with the source configuration and / or apply DAPS operations (continue to use the source in parallel with the target connection). In this example, the second reconfiguration message Rc2 includes fields / bits indicating that the UE should switch to a reduced source configuration and / or a target configuration for the option that the UE previously indicated, for example, in the MR message, to support DAPS, such that the first reconfiguration message Rc1 may not be required or is not required.

[0238] At operation 9, in this example, the method includes sending a third reconfiguration message Rc3 from the target gNB to the UE for reconfiguring the UE to switch to the full target configuration and stop DAPS. In this example, the third reconfiguration message Rc3 includes fields / bits specifying that the UE will release the source configuration (i.e., stop DAPS operations).

[0239] Feature 3

[0240] Feature 3 is related to the failure procedure (see normal procedure).

[0241] In one example, the method includes, for example, if the target connection selected by the target gNB together with the source configuration does not take into account the UE capabilities or the target gNB does not (properly) support DAPS, initiating a fallback to normal HO by the source gNB. In one example, the fallback includes a fallback to normal HO or a fallback to Rel-14 MBB (for LTE and also possibly for NR).

[0242] In this way, the handling of HO is improved when a failure occurs, thereby reducing latency and thus decreasing the likelihood of losing the radio connection. More specifically, for example, by falling back to normal HO, compared to rejecting DAPS HO and then initiating and executing normal HO, normal HO can be completed relatively faster.

[0243] Overview of Features 4 and 5

[0244] Starting point / Generally:

[0245] The network needs to know in detail what the UE is capable of. That is, whether the UE can a) add Rx support to the current source configuration in the same band as the source PCell (intra-frequency HO) or b) the band of the target PCell (inter-frequency).

[0246] This capability involves RF (additional support for bands) as well as baseband characteristics (e.g., the UE can support a limited number of MIMO layers).

[0247] The goal is the UE's ability to indicate the period for DAPS operation through some limited signaling changes.

[0248] Extending the UE capabilities with something similar to CA / DC capabilities (but now specific to DAPS) seems excessive.

[0249] Options for coverage:

[0250] Relative / responsive (Feature 4): The UE provides capabilities relative to the current / specific configuration

[0251] In the MR message or in response, i.e., in ReconfigurationComplete. The UE capabilities for DAPS operation can include:

[0252] The UE can target a reduced target configuration for which it supports DAPS (only the PCell);

[0253] For simplicity, the indication can include few parameters, e.g., indication of the supported bandwidth((s) of part(s)) and feature set combination and / or even just #MIMO layers;

[0254] Reduction of the source configuration, i.e., which source configurations need to be reduced to enable the DAPS-supported proposed reduced target configuration (as in the previous item);

[0255] Request help regarding the mode(s) for TDM operation for the Rx and / or Tx network to configure:

[0256] UE capability extension for UEs capable of CA / DC (Feature 5): Indicate whether the UE supports DAPS based on its CA / DC capabilities (i.e., the network can use any supported BC for DAPS and has the same feature set combination).

[0257] Per-UE capability indication, i.e., indicate the support for DAPS for BCs for which no DAPS-specific signaling is provided per BC (i.e., the default value indicates whether it is the same as the CA / DC capabilities).

[0258] The per-BC capability indication for the relevant BC DAPS support is different from the per-UE setting.

[0259] Per-BC capability indication of the feature set combination (FSC) supported by DAPS.

[0260] Note: Extensive capability signaling should be avoided, i.e., the per-BC indication of DAP-specific features (FSC) is costly and complex.

[0261] UE capability extension for UEs not capable of CA / DC.

[0262] Similar to the above-mentioned patterns, e.g., for TDM operations.

[0263] Feature 4

[0264] Feature 4 relates to signaling of UE capabilities in a relative or responsive manner in order to limit the signaled UE capabilities. The method includes, for example, signaling DAPS capabilities relative to the current or a specific configuration using a ReconfigurationComplete message or in the ReconfigurationComplete message or in a Measurement Report (MR) message. For simplicity, the method may also include indicating DAPS capabilities / configurations for DAPS operation support by a few basic parameters, e.g., indicating the supported bandwidth ((multiple) parts) and feature set combinations and / or even just the #MIMO layers.

[0265] In this way, the amount of signaling required to indicate DAPS capabilities is reduced.

[0266] The method includes the UE indicating UE capability information, including DAPS capabilities, to the source gNB.

[0267] In one example, the DAPS capabilities define the supported configurations relative to the current or a specific configuration.

[0268] In one example, the DAPS capabilities are included in the ReconfigurationComplete message or the MR message.

[0269] In one example, the MR message indicates the UE DAPS capabilities relative to the current source configuration (i.e., with the source gNB) and / or relative to the (potential) target configuration (i.e., with the target gNB) for which the MR was triggered. For example, the UE may indicate a reduction of the source configuration required to enable DAPS with a potential target PCell and, optionally, one or more configuration options and / or limitations for such a target PCell configuration.

[0270] In one example, the DAPS capabilities define the supported configurations relative to the current or a specific configuration.

[0271] In one example, the DAPS capabilities are included in the ReconfigurationComplete message or the MR message.

[0272] In one example, the UE indicates the DAPS capabilities in the ReconfigurationComplete message, i.e., indicates the DAPS capabilities relative to the updated source configuration resulting from a previous reconfiguration message.

[0273] In one example, the MR message indicates the DAPS capabilities with respect to the current source configuration and / or for the target for which the MR was triggered.

[0274] Figure 6 is schematically depicted in more detail Figure 3 The method of. More specifically, Figure 6 relates to the indication of capabilities.

[0275] Referring to Figure 6 , at operation 1, the method may include the source gNB sending UE capability information to the target gNB. The UE capability information may include DAPS capabilities.

[0276] At operation 2, the method may include the source gNB sending a measurement report to the target gNB. The measurement report may include DAPS capabilities and configuration assistance.

[0277] Feature 5

[0278] Feature 5 relates to the signaling of DAPS capabilities using the UE capability framework, particularly for UEs having carrier aggregation (CA) and / or dual connectivity (DC) capabilities in terms of the supported band combination (BC) capabilities.

[0279] In this way, the existing UE capability framework is reused in an efficient manner.

[0280] Note that whether signaled in the method of Feature 4 or in the method of Feature 5, the DAPS capabilities are applied to the inter-node coordination / negotiation regarding the UE capability split as described above, where, for example, the source clarifies and the target adopts the remainder (a single option provided by the source) (i.e., Feature 1 Option B).

[0281] The method includes the UE indicating DAPS capabilities to the source gNB in the UE capability information.

[0282] In one example, the UE indicating UE capability information to the source gNB includes the UE indicating per-UE capability indication regarding support for DAPS. For example, the per-UE DAPS capability indication indicates whether DAPS is supported for a BC for which the per-BC capability signaling does not include DAPS-specific capabilities (i.e., the per-UE capability relates to a default value, e.g., indicating whether DAPS is supported with the same capabilities as the CA / DC capabilities).

[0283] In one example, the UE indicating UE capability information to the source gNB includes the UE indicating the DAPS capabilities within the per-BC capabilities, e.g., for the relevant BC DAPS, supporting a different default value than that indicated by the per-UE DAPS capability setting.

[0284] In one example, the UE indicating UE capability information to the source gNB includes the UE indicating, within each BC capability, a Feature Set Combination (FSC) that supports DAPS.

[0285] In one example, the UE indicating UE capability information to the source gNB includes the UE indicating a mode for TDM operation, such as where the UE includes and / or the UE is a non-CA / DC capable UE.

[0286] More specifically, Feature 5 may include and / or relate to:

[0287] UE capability extension for CA / DC capable UEs: indicating whether the UE supports DAPS based on its CA / DC capability (i.e., the network can use any supported BC for DAPS and has the same Feature Set Combination).

[0288] Per-UE capability indication, i.e., indicating DAPS support for a BC for which there is no DAPS-specific signaling provided per BC (i.e., the default value indicates whether it is the same as the CA / DC capability).

[0289] The per-BC capability indication for relevant BC DAPS support is different from the per-UE setting.

[0290] Per-BC capability indication of the Feature Set Combination (FSC) that supports DAPS.

[0291] Note: Extended capability signaling should be avoided, i.e., per-BC indication of DAP-specific functions (FSC) is costly and complex.

[0292]

Table 1

[0293] Example

[0294]

[0295]

[0296] What situations should we pay attention to:

[0297] No single LTE UE implementation supports DC, i.e., we should focus on truly simple technical solutions.

[0298] For NR, the UE can support DC for some BCs, but does not support the BCs required for DAPS on the source / target PCell.

[0299] Operations in the target may be restricted, e.g., no SCell, limited bandwidth, and MIMO layers.

[0300] Key points discussed previously:

[0301] Target - restricted operations, e.g., no SCell, limited bandwidth, and MIMO layers.

[0302] UE does not support CA / DC, UE operation with capability splitting.

[0303] The target configures cells in the same or different frequency bands (in different BWPs) (intraF / interF DAPSHO).

[0304] Some support for dual RX

[0305] TDM operation for Tx / UL? What conversion time will FFS apply?

[0306] UE supports CA / DC, UE operation with capability splitting

[0307] UE supports BC including [B1, B2, B3], and more options.

[0308] B1 and B2 support in - band CA.

[0309] PCell change options:

[0310] IntraF: The source configures the PCell on B1 and B2, and the target configures the PCell on B2 (in - band)

[0311] InterF#1: The source configures the PCell on B1 and B2, and the target configures the PCell on B2 (in - band)

[0312] InterF#2: The source configures the PCell on B1 and B2, and the target configures the PCell on B3 (not in - band)

[0313] Capability splitting method

[0314] When reusing CA / DC capabilities and the same interaction,

[0315] The source indicates which allowed BCs (including feature sets) the target can select from;

[0316] When the UE capability includes a separate capability for DAPS, the above - mentioned method can also be used,

[0317] For some BCs, bits indicate support for DAPS (with the same feature set combination),

[0318] For some BCs that support DAPS, separate feature set combinations.

[0319]

Table 2

[0320]

[0321]

[0322] Figure 7 A flowchart is schematically depicted showing a method for DAPS handover of a UE from a source gNB to a target gNB according to example embodiments disclosed herein.

[0323] Referring to Figure 6 and Figure 7 the source gNB may receive UE capability information from the UE (operation S710). The UE may indicate its DAPS capability to the source gNB by using the UE capability information. The source gNB may coordinate a DAPS handover request of the UE from the source gNB to the target gNB at least in part based on the DAPS capability of the UE (operation S720). In some embodiments, the target gNB may coordinate the DAPS handover request of the UE at least in part based on the DAPS capability of the UE. The source gNB may reconfigure the UE from the source gNB to the target gNB (operation S730). In some embodiments, the target gNB may reconfigure the UE from the source gNB to the target gNB.

[0324] Glossary

[0325] CA: Carrier Aggregation

[0326] BC: Broadcast

[0327] MC: Multicast

[0328] DC: Dual Connectivity

[0329] MR: Multi-Radio

[0330] PCell: Primary Cell

[0331] SCell: Secondary Cell

[0332] MR-DC: Multi-RAT Dual Connectivity

[0333] 5GC: 5G Core Network

[0334] 5GS: 5G System

[0335] AMF: Access and Mobility Management Function

[0336] EN-DC: E-UTRA-NR Dual Connectivity

[0337] EPS: Evolved Packet System

[0338] MBB: Mobile Broadband

[0339] MR-DC: Multi-RAT Dual Connectivity

[0340] NG-RAN: NG Radio Access Network

[0341] NR: New Radio

[0342] OAM: Operation, Administration and Maintenance

[0343] PCF: Policy Control Function

[0344] RRC: Radio Resource Control

[0345] SI: System Information

[0346] SIB: System Information Block

[0347] UDM: Unified Data Management

[0348] UDR: Unified Data Repository

[0349] UDSF: Unstructured Data Storage Function

[0350] Although the preferred embodiments have been shown and described, those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the present disclosure as defined in the appended claims and as described above.

[0351] Please note all papers and documents that are submitted simultaneously with or prior to this specification in connection with this application. These papers and documents are publicly available for inspection together with this specification, and the content of all these papers and documents is incorporated herein by reference.

[0352] All features disclosed in this specification (including any appended claims and drawings), and / or all steps of any method or process so disclosed, may be combined in any combination, except combinations in which at most some of such features and / or steps are mutually exclusive.

[0353] Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims and drawings) may be replaced by an alternative feature serving the same, equivalent or similar purpose. Thus, unless otherwise expressly stated, each feature disclosed is only one example of a series of equivalent or similar features.

[0354] The present disclosure is not limited to the details of the foregoing embodiments. The present disclosure extends to any novel one or any novel combination of the features disclosed in this specification including any appended claims and drawings, or to any novel one or any novel combination of the steps of any method or process so disclosed.

[0355] Although the present disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes may be made in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method for dual active protocol stack (DAPS) handover of a user equipment (UE) performed by a source base station (BS) in wireless communication, the method comprising: Receiving, from the UE, UE capability information related to DAPS, wherein the UE capability information includes per-band combination (BC) capability information, and wherein each BC capability information includes the UE's DAPS capability and a feature set combination (FSC) supported by DAPS; Sending a handover request message for the UE to the target BS, wherein the handover request message includes the UE capability information; Receiving a handover request confirmation message from the target BS, the handover request confirmation message including a selected DAPS configuration option; Sending reconfiguration information to the UE, the reconfiguration information including the source configuration during DAPS together with a field indicating that the UE delays applying this reduced source configuration until DAPS; Sending reconfiguration information to the UE, the reconfiguration information including the target configuration to be used during DAPS together with a field specifying that the UE continues with the source configuration; Forwarding a first reconfiguration message from the target BS, the first reconfiguration message including a field indicating that the source BS part of the DAPS operation will stop and the source BS part of the DAPS configuration will be released; And Sending the first reconfiguration message to the UE.

2. The method according to claim 1, further comprising: Sending a second reconfiguration message to the UE for reducing the UE capabilities required with respect to the source BS, and wherein the second reconfiguration message includes at least one of a field or a bit indicating that the UE applies the received configuration with a delay.

3. The method according to claim 1, further comprising: Sending a third reconfiguration message to the UE for reconfiguring the UE to initiate the DAPS handover, and wherein the third reconfiguration message includes an indication of whether to apply DAPS operation.

4. The method according to claim 3, wherein The third reconfiguration message includes at least one of a field or a bit specifying a reduced source configuration or a target configuration for which the UE should apply an option previously indicated by the UE for supporting DAPS.

5. The method according to claim 1, wherein, The UE capability information includes the UE's DAPS capability, wherein the UE capability information includes the UE's carrier aggregation capability, wherein the UE capability information includes the UE's dual connectivity capability, wherein the DAPS capability defines the supported configuration with respect to the current or a specific configuration, wherein the DAPS capability includes per-UE capabilities, wherein the UE capability information includes a mode for time-division multiplexing (TDM) operation, and wherein the UE includes a UE capable of non-carrier aggregation / dual connectivity (CA / DC).

6. A method for dual active protocol stack (DAPS) handover of a user equipment (UE) performed in wireless communication, the method comprising: Sending UE capability information related to DAPS to the source base station (BS), wherein the UE capability information includes per-band combination (BC) capability information, and wherein each BC capability information includes the UE's DAPS capability and a feature set combination (FSC) supported by DAPS; Receiving reconfiguration information from the source BS, the reconfiguration information including the source configuration during DAPS together with a field indicating that the UE delays applying this reduced source configuration until DAPS; Receive reconfiguration information from the source BS, the reconfiguration information including a target configuration to be used during DAPS together with a field specifying that the UE continues with the source configuration; and Receive a first reconfiguration message from the source BS, the first reconfiguration message including a field indicating that the source BS part of the DAPS operation will stop and the source BS part of the DAPS configuration will be released to the UE.

7. The method according to claim 6, further comprising: Receive a second reconfiguration message from the source BS for reducing the UE capabilities required with respect to the source BS, wherein the second reconfiguration message includes at least one of a field or a bit indicating a delay for the UE to apply the received configuration.

8. The method according to claim 6, further comprising: Receive a third reconfiguration message from the source BS for reconfiguring the UE to initiate the DAPS handover, wherein the third reconfiguration message includes an indication of whether to apply the DAPS operation.

9. The method according to claim 8, wherein The third reconfiguration message includes at least one of a field or a bit specifying a reduced source configuration or a target configuration for the UE to apply the options previously indicated by the UE for supporting DAPS.

10. The method according to claim 6, wherein, UE capability information includes the DAPS capabilities of the UE, wherein the UE capability information includes the carrier aggregation capabilities of the UE, wherein the UE capability information includes the dual connectivity capabilities of the UE, wherein the DAPS capabilities define the supported configurations with respect to the current or a specific configuration, wherein the DAPS capabilities include per-UE capabilities, wherein the UE capability information includes the mode for time-division multiplexing TDM operation, and wherein the UE includes a UE capable of non-carrier aggregation / dual connectivity CA / DC.

11. A source base station BS for a dual-active protocol stack DAPS for handover of a user equipment (UE), the source BS comprising: At least one processor, wherein the at least one processor is configured to: Receive UE capability information related to DAPS from the UE, wherein the UE capability information includes per-band combination BC capability information, and wherein each BC capability information includes the DAPS capabilities of the UE and a feature set combination FSC supported by DAPS, Send a handover request message for the UE to the target BS, wherein the handover request message includes the UE capability information, Receive a handover request confirmation message from the target BS, the handover request confirmation message including a selected DAPS configuration option, Send reconfiguration information to the UE, the reconfiguration information including the source configuration during DAPS together with a field indicating that the UE delays applying such a reduced source configuration until DAPS, Send reconfiguration information to the UE, the reconfiguration information including a target configuration to be used during DAPS together with a field specifying that the UE continues with the source configuration, Forward a first reconfiguration message from the target BS, the first reconfiguration message including a field indicating that the source BS part of the DAPS operation will stop and the source BS part of the DAPS configuration will be released to the UE, and Send a first reconfiguration message to the UE.

12. The BS according to claim 11, wherein the at least one processor is further configured to operate according to one of the methods described in claims 2 to 5.

13. A user equipment (UE) with a dual active protocol stack (DAPS) for handover in wireless communication, the UE comprising: At least one processor, wherein the at least one processor is configured to: Send UE capability information related to DAPS to a source base station (BS), wherein the UE capability information includes per-band combination (BC) capability information, and wherein each BC capability information includes the UE's DAPS capability and a feature set combination (FSC) supported by DAPS, Receive reconfiguration information from the source BS, the reconfiguration information including the source configuration during DAPS together with a field indicating that the UE delays applying such reduced source configuration until DAPS, Receive reconfiguration information from the source BS, the reconfiguration information including the target configuration to be used during DAPS together with a field specifying that the UE continues with the source configuration, and Receive a first reconfiguration message from the source BS, the first reconfiguration message including a field indicating that the source BS part of the DAPS operation will stop and the source BS part of the DAPS configuration will be released.

14. The UE according to claim 13, wherein the at least one processor is further configured to operate according to one of the methods described in claims 7 to 10.

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