Method and apparatus for dual connectivity condition switching with on-time data forwarding

Abstract

Methods and apparatus for dual connectivity condition switching with on-time data forwarding are presented. A User Equipment CHO configured to operate in dual connectivity during a Conditional Handover CHO is presented that establishes a connection towards a primary cell of a source primary node and towards a primary secondary cell of a source secondary node. The user equipment receives a transmission indication from the source master node, wherein the transmission indication enables the user equipment to send a CHO execution indication towards the source master node via the source secondary node. Finally, the user equipment sends, via the source secondary node, a CHO execution indication towards the source primary node, and processes the CHO of the primary cell towards the target primary node. The invention also provides a method, a network node and a functional unit of the network node involved in the proposed dual connectivity condition switching.

Description

Technical Field

[0001] The subject disclosure generally relates to wireless communication systems, and more particularly to conditional handover in wireless communication systems. More specifically, the subject disclosure provides a method and apparatus for conditional handover of dual connectivity with on-time data forwarding. Background Art

[0002] Wireless communication systems are constantly evolving. There is a need for higher data rates and high quality of service. Reliability requirements are also constantly increasing, and methods and means to ensure reliable connections and data services while keeping transmission delays to a minimum are also constantly evolving.

[0003] The evolving network enables new services for clients. One service is dual connectivity, where the user equipment communicates with both a primary node base station and a secondary node base station. Dual connectivity improves data throughput and mobility robustness. Another service is conditional handover, which further improves mobility robustness. For conditional handover, the network can prepare multiple target cells for which conditional handover configurations are associated with execution conditions evaluated by the user equipment.

[0004] Using dual connectivity and conditional switching may require techniques for dual connectivity conditional switching. Summary of the invention

[0005] According to the first aspect of the subject disclosure, a user equipment (UE) is proposed, which is configured to support operation in a dual-connection mode within at least one radio access network RAN, and is configured to support conditional handover CHO. The user equipment includes at least one processor and at least one memory, and the memory includes a computer program code. When executed together with at least one processor, the program code enables the user equipment to establish a connection to a primary cell (primary cell) toward a source master node (master node), and to establish a connection to a primary and secondary cell toward a source auxiliary node. The program code further enables the UE to receive a transmission indication from the source master node, wherein the transmission indication enables the user equipment to send a CHO execution indication toward the source master node via the source auxiliary node, and to send a CHO execution indication toward the source master node via the source auxiliary node. Finally, the program code enables the UE to process the CHO of the primary cell toward the target master node.

[0006] In an embodiment, the transmission indication further configures the user equipment how to send the CHO execution indication towards the source primary node via the source secondary node. In another embodiment, the UE is configured to send the CHO execution indication towards the source secondary node via at least one of a signaling radio bearer or a split bearer terminated at the source primary node.

[0007] In a further embodiment, the transmission indication is received as part of a radio resource control RRC reconfiguration message. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message, the message further comprising: a CHO configuration of at least one target primary cell of at least one target primary node. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with a source primary node.

[0008] In a further embodiment, the program code causes the UE to further receive at least one CHO execution condition for at least one target primary cell toward at least one target primary node from the source primary node, perform measurements related to the received at least one CHO execution condition, and in response to at least one of the at least one CHO execution conditions being satisfied for the target primary node based on the measurement value, send a CHO execution indication toward the source primary node via the source secondary node, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication.

[0009] In a related embodiment, the program code further causes the UE to maintain a connection toward at least the primary and secondary cells of the source secondary node when sending the CHO execution condition satisfaction indication, and terminate the connection toward the source primary node after sending the CHO execution condition satisfaction indication to stop data transmission and reception. In some embodiments, the CHO execution condition satisfaction indication includes measurement values ​​related to the primary cell of the source primary node and the primary cell of the target primary node that satisfy the CHO execution condition. In some embodiments, the CHO execution condition satisfaction indication further includes measurement values ​​related to multiple cells measured at the user equipment and available when the CHO execution condition is satisfied.

[0010] In a further embodiment, the CHO execution condition is received as part of a radio resource control RRC message. In some embodiments, the CHO execution condition is included in the same message as at least one of a CHO transmission indication of at least one target primary cell of at least one target primary node, or a CHO configuration. In some embodiments, the message used to send the CHO execution condition satisfaction indication further includes: an identifier of the source primary node.

[0011] In a further embodiment, the program code further causes the UE to send a CHO execution indication toward the source primary node via the source secondary node in response to determining that a radio link failure associated with a connection toward a primary cell of the source primary node is responsive to determining that a radio link quality associated with a connection toward a primary cell of the source primary node is beginning to decrease according to at least one criterion, and to send a measurement value associated with at least one potential target primary cell of at least one potential target primary node toward the source primary node via the source secondary node. In some embodiments, the at least one criterion includes at least one threshold value, and a radio link quality decrease below the threshold value is determined when a timer for radio link failure detection is running or after receiving a desynchronization indication from a lower layer.

[0012] According to a second aspect of the subject disclosure, a source master node is provided, configured to: support establishing a connection toward a user equipment, the user equipment being configured to support operating in a dual-connection manner with a primary cell of the source master node and a primary and secondary cell of a source secondary node, and supporting conditional handover CHO. The source master node includes at least one processor and at least one memory, the memory including computer program code, enabling the source master node to send a transmission indication to the user equipment when executed together with the at least one processor, wherein the transmission indication enables the user equipment to send a CHO execution indication toward the source master node via the source secondary node, and in response to receiving the CHO execution indication from the source secondary node, initiate data forwarding toward the primary cell of the target master node.

[0013] In an embodiment, the transmission indication further configures the user equipment how to send the CHO execution indication towards the source primary node via the source secondary node. In some embodiments, the transmission indication configures the user equipment to send the CHO execution indication towards the source secondary node via at least one of a signaling radio bearer terminated at the source primary node, or a split bearer.

[0014] In a further embodiment, the transmission indication is received as part of a radio resource control RRC reconfiguration message. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message, the message further comprising: a CHO configuration of at least one target primary cell of at least one target primary node. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with a source primary node.

[0015] In a further embodiment, the program code further causes the source master node to send at least one CHO execution condition for conditional switching toward at least one target master cell of at least one target master node, and receive a CHO execution indication from the source secondary node, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication.

[0016] In a related embodiment, the program code further causes the source master node to terminate the connection toward the user equipment in response to receiving the CHO execution condition satisfaction indication to stop data transmission and reception. In some embodiments, the CHO execution condition satisfaction indication includes: measurement values ​​related to the primary cell of the source master node and the primary cell of the target master node that satisfy the CHO execution condition. In some embodiments, the CHO execution condition satisfaction indication further includes measurement values ​​related to multiple cells measured at the user equipment and available when the CHO execution condition is satisfied.

[0017] In a further embodiment, the CHO execution condition is sent as part of a radio resource control RRC message. In some embodiments, the CHO execution condition is included in the same message as at least one of a CHO transmission indication of at least one target primary cell of at least one target primary node or a CHO configuration. In some embodiments, the message used to send the CHO execution condition satisfaction indication further includes: an identifier of the source primary node.

[0018] In a further embodiment, the program code further causes the source primary node to receive a CHO execution indication from the source secondary node, wherein the CHO execution indication includes: a CHO recovery execution indication, wherein the CHO recovery execution indication is sent in response to a radio link failure associated with a connection toward a primary cell of the source primary node determined by the user equipment. In a related embodiment, the program code further causes the source primary node to receive a measurement value associated with at least one potential target primary cell of at least one potential target primary node from the source secondary node, wherein the measurement value is sent in response to the user equipment determining, according to at least one criterion, that a radio link quality associated with a connection toward a primary cell of the source primary node begins to degrade.

[0019] In some embodiments, the at least one criterion comprises at least one threshold, and a degradation of the radio link quality below the threshold is determined when a timer for radio link failure detection runs or after receiving an out-of-sync indication from a lower layer.

[0020] According to a third aspect of the subject disclosure, a network node is provided, which supports at least one of a central unit control plane function, or a third layer protocol of a radio access network, is configured to support a connection with a user equipment operating in a dual-connection manner with a primary cell of the network node and a primary and secondary cell of a source secondary node, and is configured for conditional handover CHO. The network node includes at least one processor and at least one memory, the memory including computer program code, which enables the network node to generate a radio resource control RRC message including a transmission indication when executed together with the at least one processor, wherein the transmission indication enables the user equipment to send a CHO execution indication to the network node via the source secondary node, send a radio resource control RRC message including the transmission indication to the user equipment, and in response to receiving the CHO execution indication in the radio resource control RRC message from the source secondary node, initiate data forwarding towards the primary cell of the target primary node.

[0021] In an embodiment, the network node is configured according to the source master node in the related embodiment.

[0022] According to a fourth aspect of the subject disclosure, a method for conditional handover CHO performed by a user equipment configured to operate in a dual-connection mode within at least one radio access network RAN ​​is proposed. The method includes establishing a connection toward a primary cell of a source primary node, establishing a connection toward a primary secondary cell of a source secondary node, receiving a transmission indication from the source primary node, wherein the transmission indication enables the user equipment to send a CHO execution indication toward the source primary node via the source secondary node, sending a CHO execution indication toward the source primary node via the source secondary node, and processing a CHO of a primary cell toward a target primary node.

[0023] In an embodiment, the transmission indication further configures how the user equipment sends the CHO execution indication towards the source primary node via the source secondary node. In some embodiments, the method further comprises: sending the CHO execution indication towards the source secondary node via at least one of a signaling radio bearer terminated at the source primary node, or a split bearer.

[0024] In a further embodiment, the transmission indication is received as part of a radio resource control RRC reconfiguration message. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message, the message further comprising: a CHO configuration of at least one target primary cell of at least one target primary node. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with a source primary node.

[0025] In a further embodiment, the method further includes: receiving at least one CHO execution condition for CHO toward at least one target primary cell of at least one target primary node from the source master node, performing measurements related to the received at least one CHO execution condition, and in response to at least one of the at least one CHO execution conditions being satisfied for the target primary node based on the measurement value, sending a CHO execution indication toward the source master node via the source secondary node, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication.

[0026] In a related embodiment, the method further includes: maintaining a connection toward at least a primary secondary cell of the source secondary node for continued data transmission and reception when sending the CHO execution condition satisfaction indication, and terminating a connection toward a primary cell of the source primary node after sending the CHO execution condition satisfaction indication. In some embodiments, the CHO execution condition satisfaction indication includes: measurement values ​​related to a primary cell of the source primary node and a primary cell of the target primary node that satisfy the CHO execution condition. In some embodiments, the CHO execution condition satisfaction indication further includes: measurement values ​​related to a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

[0027] In an embodiment, the CHO execution condition is received as part of a radio resource control (RRC) message. In some embodiments, the CHO execution condition is included in the same message as at least one of a CHO transmission indication of at least one target primary cell of at least one target primary node, or a CHO configuration. In some embodiments, the message for sending the CHO execution condition satisfaction indication further includes an identification of the source: primary node.

[0028] In a further embodiment, the method further includes, in response to determining a radio link failure associated with a connection to a primary cell toward a source primary node, sending a CHO execution indication toward the source primary node via a source secondary node, wherein the CHO execution indication includes: a CHO recovery execution indication. In a related embodiment, the method further includes, in response to determining that the radio link quality associated with a connection to a primary cell toward the source primary node begins to decline according to at least one criterion, sending a measurement value associated with at least one potential target primary cell of at least one potential target primary node toward the source primary node via the source secondary node. In some embodiments, the at least one criterion includes at least one threshold value, and a radio link quality decline below the threshold value is determined when a timer for radio link failure detection is running or after receiving a desynchronization indication from a lower layer.

[0029] According to a fifth aspect of the subject disclosure, a method for conditional handover CHO performed by a source primary node connected to a user equipment is provided, the user equipment operating in a dual-connection manner with a primary cell of the source primary node and a primary and secondary cell of a source secondary node. The method comprises: sending a transmission indication to the user equipment, wherein the transmission indication enables the user equipment to send a CHO execution indication toward the source primary node via the source secondary node, and in response to receiving the CHO execution indication from the source secondary node, initiating data forwarding toward the primary cell of the target primary node.

[0030] In an embodiment, the transmission indication further configures the user equipment how to send the CHO execution indication towards the source primary node via the source secondary node. In some embodiments, the transmission indication configures the user equipment to send the CHO execution indication towards the source secondary node via at least one of a signal radio bearer terminated at the source primary node or a split bearer.

[0031] In a further embodiment, the transmission indication is received as part of a radio resource control RRC reconfiguration message. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message, the message further comprising: a CHO configuration of at least one target primary cell of at least one target primary node. In some embodiments, the transmission indication is received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with a source primary node.

[0032] In a further embodiment, the method further comprises: sending at least one CHO execution condition for conditional switching toward at least one target primary cell of at least one target primary node, and receiving a CHO execution indication from a source secondary node, wherein the CHO execution indication comprises: a CHO execution condition satisfaction indication. In some embodiments, the method further comprises: terminating a connection toward a primary cell of the source primary node in response to receiving the CHO execution condition satisfaction indication. In some embodiments, the CHO execution condition satisfaction indication comprises: measurement values ​​associated with a primary cell of the source primary node and a primary cell of the target primary node that satisfy the CHO execution condition. In some embodiments, the CHO execution condition satisfaction indication further comprises: measurement values ​​associated with a plurality of cells measured at a user equipment and available when the CHO execution condition is satisfied.

[0033] In a further embodiment, the CHO execution condition is sent as part of a radio resource control RRC message. In some embodiments, the CHO execution condition is included in the same message as at least one of a CHO transmission indication of at least one target primary cell of at least one target primary node or a CHO configuration. In some embodiments, the message for sending the CHO execution condition satisfaction indication further includes: an identifier of the source primary node.

[0034] In a further embodiment, the method further comprises: receiving a CHO execution indication from a source secondary node, wherein the CHO execution indication comprises a CHO recovery execution indication, wherein the CHO recovery execution indication is sent in response to a determination by a user equipment of a radio link failure associated with a connection to a primary cell toward the source primary node. In a related embodiment, the method further comprises: receiving a measurement value associated with at least one potential target primary cell of at least one potential target primary node from the source secondary node, wherein the measurement value is sent in response to a determination by the user equipment, based on at least one criterion, that the radio link quality associated with the connection to the primary cell toward the source primary node begins to degrade. In some embodiments, the at least one criterion comprises at least one threshold, and a radio link quality degradation below a threshold is determined when a timer for radio link failure detection is running or after receiving a desynchronization indication from a lower layer.

[0035] The above aspects and features can be implemented in systems, devices, methods, articles, and non-transitory computer-readable media according to the desired configuration. The subject disclosure can be implemented and used in a variety of different types of devices, including but not limited to mobile phones, tablets, wearable computing devices, portable media players, and any other various computing devices.

[0036] This summary is intended to provide a brief overview of some aspects and features disclosed in accordance with the subject matter. Therefore, it is understood that the above features are merely examples and should not be interpreted as reducing the scope of the subject matter disclosed in any way. Other features, aspects and advantages of the subject matter disclosed will become apparent from the following detailed description, drawings and claims.

[0037] List of abbreviations

[0038] In the subject disclosure, the following abbreviations are used and should be understood in light of the definitions given:

[0039] 3GPP Third Generation Partnership Project

[0040] 5G Fifth Generation (mobile communication network)

[0041] 5GC 5G Core Network

[0042] NG-RAN Next Generation Radio Access Network

[0043] NR New Radio, 5G

[0044] LTE Long Term Evolution, 4G

[0045] BS Base Station

[0046] UE User Equipment

[0047] HO Handover

[0048] CHO Condition Switch

[0049] DC Dual Connection

[0050] gNB gNodeB(NR)

[0051] eNB eNodeB(LTE)

[0052] SCG Secondary Cell Group

[0053] MCG Master Cell Group

[0054] PCell Primary Cell

[0055] PSCell primary and secondary cells

[0056] MN Master / Primary Node

[0057] SN Secondary Node

[0058] RRC Radio Resource Control Reconfiguration

[0059] SRB Signalling Radio Bearer

[0060] gNB-CU-CP gNodeB Central Unit Control Plane

[0061] gNB-CU-UP gNodeB Central Unit User Plane

[0062] gNB-DU gNodeB distributed unit

[0063] AMF Access and Mobility Function

[0064] UPF User Plane Function BRIEF DESCRIPTION OF THE DRAWINGS

[0065] A better understanding of the subject disclosure may be obtained when the following detailed description of various embodiments is considered in conjunction with the following drawings:

[0066] Figure 1 A schematic diagram of an example communication system including a base station and a plurality of communication devices is shown;

[0067] Figure 2 A schematic diagram of an example mobile communication device is shown;

[0068] Figure 3 A schematic diagram of an example control arrangement is shown;

[0069] Figure 4A and Figure 4B Describes the NG-RAN architecture;

[0070] Figure 5A flow chart of dual connectivity conditional switching with on-time data forwarding performed by a user equipment is presented;

[0071] Figure 6 A flow chart of dual connection conditional switching with on-time data forwarding performed by a source master node is presented;

[0072] Figure 7 A flow chart of dual connectivity conditional switching with on-time data forwarding performed by a control plane central unit of a source base station is presented;

[0073] Figure 8 A message flow diagram showing an example overall dual connection condition switching; and

[0074] Fig. 9 A message flow diagram of an example overall dual-connection conditional handover for conditional handover recovery is shown. DETAILED DESCRIPTION

[0075] Before explaining the examples in detail, refer to Figures 1 to 3 Certain general principles of wireless communication systems and mobile communication devices are briefly explained to aid understanding of the underlying technology of the described examples.

[0076] In the wireless communication system 100, as Figure 1 As shown, mobile communication devices, user devices, user equipment (UE) 102, 104, 105 provide wireless access via at least one base station (e.g., next generation NB, gNB), similar wireless transmission and / or reception nodes or network nodes. The base station may be controlled or assisted by at least one appropriate controller device to enable operation and management of mobile communication devices communicating with the base station. The controller device may be located in a radio access network (RAN) (e.g., wireless communication system 100) or a core network (CN) (not shown), and may be implemented as a central device, or its functions may be distributed across multiple devices. The controller device may be part of a base station and / or provided by an independent entity such as a radio network controller (RNC). In Figure 1 In the figure, control means 108 and 109 are shown as controlling respective macro-level base stations 106 and 107. The control means of the base stations may be interconnected with other control entities. The control means are typically provided with memory capacity and at least one data processor. The control means and functions may be distributed between multiple control units. In some systems, the control means may additionally or alternatively be provided in the RNC.

[0077] exist Figure 1 In FIG. 1 , base stations 106 and 107 are shown connected to a wider communications network 113 via a gateway 112. A further gateway function may be provided to connect to another network.

[0078] As used herein, the term "base station" has the full breadth of its ordinary meaning, including at least a wireless communication station installed in a fixed location and used to communicate as part of a wireless telephone system or wireless system. The communication area (or coverage area) of a base station may be referred to as a "cell". The base station and UE may be configured to communicate over a transmission medium using any of the various radio access technologies (RATs) (also referred to as wireless communication technologies or telecommunication standards) described below. Figure 1 As illustrated, while a base station may serve as a "serving cell" for a UE, the UE may also be able to receive signals from (and possibly within communication range of) one or more other cells (which may be provided by the base station and / or any other base station), which may be referred to as "neighboring cells."

[0079] Smaller base stations 116, 118 and 120 may also be connected to the network 113, for example, through a separate gateway function and / or via a controller of a macro-level site. Base stations 116, 118 and 120 may be pico-level base stations or femto-level base stations, etc. In the present example, sites 116 and 118 are connected via gateway 111, while site 120 is connected via controller device 108. In some embodiments, smaller sites may not be provided. Smaller base stations 116, 118 and 120 may be part of a second network, such as a wireless local area network (WLAN), and may be a WLAN access point (AP). Communication devices 102, 104, 105 may access the communication system based on various access technologies, such as code division multiple access (CDMA) or wideband CDMA (WCDMA). Other non-limiting examples include time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof, such as interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA), etc.

[0080] An example of a wireless communication system is the standardized architecture of the Third Generation Partnership Project (3GPP). Developments based on the latest 3GPP are generally referred to as the Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio access technology. The various development stages of the 3GPP specifications are referred to as releases. The newer development of LTE is generally referred to as Advanced LTE (LTE-A). LTE (or LTE-A) adopts a wireless mobile architecture called Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network called Evolved Packet Core (EPC). The base stations of such systems are called Evolved or Enhanced Node Bs (eNBs) and provide E-UTRAN features, such as user plane packet data convergence / radio link control / media access control / physical layer protocols (PDCP / RLC / MAC / PHY) and control plane radio resource control (RRC) protocols for communication devices. Other examples of wireless access systems include those provided by system base stations based on technologies such as WLAN and / or Worldwide Interoperability for Microwave Access (WiMax). The base station can provide coverage of an entire cell or similar wireless service area. The core network elements include the Mobility Management Entity (MME), the Serving Gateway (S-GW) and the Packet Gateway (P-GW).

[0081] 5G or NR concepts are examples of suitable communication systems. The network architecture in NR may be similar to LTE-A. The base stations of NR systems may be referred to as next generation node Bs (gNBs). Changes in network architecture may depend on the need to support various wireless technologies and more sophisticated quality of service (QoS) support, as well as some on-demand requirements for QoS levels that support quality of experience (QoE) from a user perspective. In addition, network-aware services and applications, as well as service- and application-aware networks, bring changes to the architecture. These are related to information-centric networks (ICNs), user-centric content delivery networks (UC-CDN) approaches. NR may use multiple-input multiple-output (MIMO) antennas, many more base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperation with small sites, and may also adopt various wireless technologies to achieve better coverage and improved data rates.

[0082] Future networks may utilize network function virtualization (NFV), a network architecture concept that proposes virtualizing network node functions into "components" or entities that can be operationally connected or linked together to provide services. A virtualized network function (VNF) may include one or more virtual machines that run computer program code using standard or general-purpose servers, rather than customized hardware. Cloud computing or data storage may also be used. In wireless communications, this may mean that node operations are performed at least partially in a server, host, or node that is operationally coupled to a remote radio head. It is also possible that node operations are distributed among multiple servers, nodes, or hosts. It should also be understood that the division of labor between core network operations and base station operations may be different from LTE, or even non-existent.

[0083] An example 5G core network (CN) includes functional entities. The CN is connected to the UE via the radio access network (RAN). The user plane function (UPF), whose role is called the PDU session anchor (PSA), can be responsible for forwarding frames back and forth between the data network (DN) and the tunnel established by 5G towards the UE exchanging services with the DN.

[0084] The UPF is controlled by a Session Management Function (SMF), which receives policies from a Policy Control Function (PCF). The CN may also include an Access and Mobility Function (AMF).

[0085] Now refer to Figure 2 Describing in more detail a possible (mobile) communication device 200, Figure 2 A partial cross-sectional schematic diagram is shown. Such a mobile communication device 200 is generally referred to as a user equipment (UE), user equipment or terminal equipment. A suitable mobile communication device 200 can be provided by any device capable of sending and receiving wireless signals. Non-limiting examples include a mobile station (MS) or a mobile device, such as a mobile phone or a so-called smart phone, a computer equipped with a wireless interface card or other wireless interface facilities (such as a USB dongle), a personal data assistant (PDA) or a tablet computer equipped with a wireless communication function, or any combination of these devices or similar devices. For example, the communication device 200 can provide data communications for carrying communications such as voice, e-mail (e-mail), text messages, multimedia, etc. Therefore, a variety of services can be provided and supplied to users via the user's communication device. Non-limiting examples of these services include two-way or multi-way calls, data communications or multimedia services, or simply access to a data communication network system, such as the Internet. Broadcast or multicast data can also be provided to users. Non-limiting examples of content include downloads, television and radio programs, videos, advertisements, various alarms, and other information.

[0086] In industrial applications, the communication device may be a modem integrated into an industrial actuator (e.g. a robotic arm) and / or a modem used as an Ethernet hub that would serve as a connection point for one or more connected Ethernet devices (the connection could be wired or wireless).

[0087] The communication device 200 is typically provided with at least one data processing entity 201, at least one memory 202, and other possible components 203 for performing the tasks it is designed to perform, including controlling access to and communicating with access systems and other communication devices, with the assistance of software and hardware. Data processing, storage and other related control means may be provided on appropriate circuit boards and / or in a chipset 204. The user may control the operation of the communication device 200 through an appropriate user interface, such as a keyboard 205, voice commands, a touch-sensitive screen or touch-sensitive pad, a combination thereof or the like. A display 208, a speaker and a microphone may also be provided. In addition, the communication device 200 may include appropriate connectors (wired or wireless) to other devices and / or for connecting external accessories (e.g., a hands-free device).

[0088] The communication device 200 may receive signals via an appropriate receiving means over the air or wireless interface 207, and may transmit signals via an appropriate wireless signal transmitting means. Figure 2 In the embodiment of the present invention, the transceiver arrangement is schematically represented by block 206. For example, the transceiver arrangement 206 may be provided by radio components and an associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the communication device 200.

[0089] If desired, the communication device 200 may also be configured, or alternatively configured, to communicate using one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one or more mobile television broadcast standards (such as ATSC-M / H or DVB-H), and / or any other wireless communication protocol. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0090] Generally speaking, Figure 2 The communication device 200 shown includes a set of components configured to perform core functions. For example, the set of components can be implemented as a system on a chip (SoC), which may include parts for various purposes. Alternatively, the set of components can be implemented as independent components or groups of components for various purposes. The set of components can be (communicatively) coupled (e.g., directly or indirectly) to various other circuits of the communication device 200.

[0091] The communication device 200 may include at least one antenna in communication with a transmitter and a receiver (e.g., a transceiver device 206). Alternatively, the transmitting and receiving antennas may be separate. The communication device 200 may also include a processor (e.g., at least one data processing entity 201), which is configured to provide signals to and receive signals from the transmitter and the receiver, respectively, and control the functions of the communication device 200. The processor may be configured to control the functions of the transmitter and the receiver by enabling control signal transmission via wires to the transmitter and the receiver. Similarly, the processor may be configured to control other elements of the communication device 200 by enabling control signals via wires connecting the processor to other elements (e.g., a display (e.g., a display 208) or a memory (e.g., at least one memory 202)). For example, a processor may be embodied in a variety of ways, including circuitry, at least one processing core, one or more microprocessors with an attached digital signal processor, one or more processors without an attached digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements, including integrated circuits, such as application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc., or some combination thereof. Thus, in some examples, a processor may include multiple processors or processing cores.

[0092] The communication device 200 can operate using one or more air interface standards, communication protocols, modulation types, access types, etc. The signals sent and received by the processor may include signaling information according to the air interface standard of the applicable cellular system, and / or any number of different wired or wireless network technologies, including but not limited to Wi-Fi, WLAN technologies, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, etc. In addition, these signals may include: voice data, user-generated data, user-requested data, etc.

[0093] For example, the communication device 200 and / or the cellular modem therein can operate according to various 3rd generation (3G) communication protocols, 4th generation (4G) communication protocols, 5th generation (5G) communication protocols, Internet Protocol Multimedia Subsystem (IMS) communication protocols (e.g., Session Initiation Protocol (SIP)), or protocols beyond 5G. For example, the communication device 200 can operate according to 4G wireless communication protocols (e.g., LTE-A, 5G, etc.), as well as similar wireless communication protocols subsequently developed.

[0094] It is understood that the processor may include circuits for implementing the audio / video and logic functions of the communication device 200. For example, the processor may include: a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, etc. The control and signal processing functions of the communication device 200 may be allocated between these devices according to their respective capabilities. The processor may also include an internal voice encoder, an internal data modem, etc. In addition, the processor may include the function of operating one or more software programs, which may be stored in the memory. In general, the processor and the stored software instructions may be configured to cause the communication device 200 to perform actions. For example, the processor is capable of running a connection program, such as a web browser. The connection program allows the communication device 200 to send and receive network content, such as location-based content, according to a protocol (e.g., Wireless Application Protocol (WAP), Hypertext Transfer Protocol (HTTP), etc.).

[0095] The communication device 200 may also include a user interface, such as a headset or speaker, a ringer, a microphone, a display, a user input interface, etc., which may be operatively coupled to the processor. As described above, the display may include a touch-sensitive display, where the user can touch and / or gesture to make selections, input values, etc. The processor may also include a user interface circuit configured to control at least some functions of one or more elements of the user interface, such as a speaker, a ringer, a microphone, a display, etc. The processor and / or the user interface circuit including the processor may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, such as software and / or firmware, stored on a memory accessible to the processor, such as a volatile memory, a non-volatile memory, etc. The communication device 200 may include a battery for powering various circuits associated with the mobile terminal, such as a circuit that provides mechanical vibration as a detectable output. The user input interface may include a device that allows the communication device 200 to receive data, such as a keyboard (e.g., keyboard 206) and / or other input devices. The keyboard may also be a virtual keyboard presented on the display or an externally coupled keyboard.

[0096] The communication device 200 may also include one or more mechanisms for sharing and / or obtaining data. For example, the communication device 200 may include a short-range radio frequency (RF) transceiver and / or interrogator, so that data can be shared with and / or obtained from electronic devices based on RF technology. The communication device 200 may include other short-range transceivers, such as infrared (IR) transceivers, Bluetooth® transceivers, and other short-range transceivers. TM (BT) Wireless Technology Operation Bluetooch TM Transceiver, Wireless USB Transceiver, Bluetooth TMLow energy transceiver, ZigBee transceiver, ANT transceiver, cellular device to device transceiver, wireless LAN link transceiver and / or any other short-range wireless technology. The communication device 200, more specifically, the short-range transceiver can send data to and / or receive data from electronic devices near the device (e.g., within 10 meters). The communication device 200 including a Wi-Fi or WLAN modem can also send and / or receive data from electronic devices according to various wireless network technologies, including 6LoWPAN, Wi-Fi, Wi-Fi low power, WLAN technology (e.g., IEEE802.11 technology, IEEE802.15 technology, IEEE802.16 technology, etc.).

[0097] The communication device 200 may include memory, such as one or more user identity modules (SIMs), one or more universal user identity modules (USIMs), one or more removable user identity modules (R-UIMs), one or more embedded universal integrated circuit cards (eUICCs), one or more universal integrated circuit cards (UICCs), etc., which can store information elements related to mobile users. In addition, the communication device 200 may include: other removable and / or fixed memories. The communication device 200 may include: volatile memory and / or non-volatile memory. For example, the volatile memory may include random access memory (RAM), including dynamic and / or static RAM, on-chip or off-chip cache memory, etc. The non-volatile memory may be embedded and / or removable, for example, it may include read-only memory, flash memory, magnetic storage devices, such as hard disks, floppy disk drives, tapes, optical disk drives and / or media, non-volatile random access memory (NVRAM), etc. Like volatile memory, non-volatile memory may include a cache area for temporarily storing data. At least a portion of the volatile and / or non-volatile memory may be embedded in the processor. The memory may store one or more software programs, instructions, information blocks, data, etc., which may be used by the device to perform the operations disclosed herein.

[0098] The memory may include an identifier, such as an International Mobile Equipment Identity (IMEI) code, that can uniquely identify the communication device 200. In this example embodiment, the processor may be configured using computer code stored in the memory to cause the processor to perform the operations disclosed herein.

[0099] Some embodiments disclosed herein may be implemented by software, hardware, application logic, or a combination of software, hardware, and application logic. For example, the software, application logic, and / or hardware may be located on a memory, a processor, or an electronic component. In some example embodiments, the application logic, software, or instruction set is stored on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any non-transitory medium that can contain, store, communicate, propagate, or transmit instructions for use by or in connection with an instruction execution system, apparatus, or device (such as a computer or data processor circuit), utilizing Figure 2 In the described examples, computer-readable media may include non-transitory computer-readable storage media, which may be any media that can contain or store instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0100] In some embodiments, the communication device 200 (i.e., UE or user equipment in the network) includes a processor (e.g., at least one data processing entity 201) and a memory (e.g., at least one memory 202). The memory includes computer program code to enable the communication device 200 to perform the following operations according to the reference Figure 5 The method performs processing.

[0101] Figure 3 An example embodiment of a control device for a communication system is shown, for example, for coupling to and / or for controlling a station of an access system, such as a RAN node, such as a base station, eNB or gNB, a relay node or a core network node, such as an MME or S-GW or P-GW, or a core network function, such as an AMF / SMF, or a server or a host. The method may be embedded in a single control device or across more than one control device. The control device may be integrated with a node or module of a core network or RAN, or may be integrated externally thereof. In some embodiments, the base station includes a separate control device unit or module. In other embodiments, the control device may be another network element, such as an RNC or a spectrum controller. In some embodiments, the base station may have such a control device as well as a control device provided in the RNC. The control device 300 may be arranged to provide control of communications in a service area of ​​the system. The control device 300 includes at least one memory 301, at least one data processing unit 302, 303 and an input / output interface 304. Via the interface, the control device 300 may be coupled to a receiver and a transmitter of the base station. The receiver and / or transmitter may be implemented as a wireless front end or a remote radio head.

[0102] Generally speaking, the control device 300 has an antenna for transmitting and receiving wireless signals. A radio frequency (RF) transceiver module coupled to the antenna receives RF signals from the antenna, converts them into baseband signals and sends them to a processor (e.g., at least one data processing unit 302, 303). The RF transceiver also converts baseband signals received from the processor, converts them into RF signals and sends them to the antenna. The processor processes the received baseband signals and calls different functional modules to execute features in the control device 300. A memory (e.g., at least one memory 301) stores program instructions and data to control the operation of the control device 300. In Figure 3 In the example of , the control device 300 also includes a protocol stack and a set of control function modules and circuits. The PDU session processing circuit processes the PDU session establishment and modification process. The policy control module configures policy rules for the UE. The configuration and control circuits provide different parameters for configuring and controlling relevant functions of the UE, including mobility management and session management. For example, suitable processors include special-purpose processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, ASICs, FPGA circuits, and other types of integrated circuits (ICs) and / or state machines.

[0103] In some embodiments, the control device 300 (i.e., a base station, a wireless transmission and / or reception point device, or a network node in a network) includes a processor (e.g., at least one data processing unit 302, 303) and a memory (e.g., at least one memory 301). The memory includes computer program code to enable the control device 300 to perform the following operations according to the reference Figure 6 The method performs processing.

[0104] Figure 4A and Figure 4B A next generation radio access network (NG-RAN) architecture 400 with a gNB 402 according to 3GPP TS38.401 V17.0.0 is described. The gNB 402 uses NR user / control plane protocols to provide services to UEs and is connected to the 5GC 401 via an NG interface and to other gNBs 402 via an Xn interface. Figure 4AThe gNB 402 in the embodiment includes: a central unit (i.e., gNB-CU) 403, and one or more distributed units (i.e., gNB-DU) 404. The gNB-CU is a logical node that hosts the RRC, SDAP, and PDCP protocols for the gNB or the RRC and PDCP protocols for the en-gNB, and controls the operation of one or more gNB-DUs 404. The gNB-CU 403 terminates the F1 interface connected to the gNB-DU 404. The dNB-DU 404 is a logical node that hosts the RLC, MAC, and PHY layers for the gNB 402 or the en-gNB, and its operation is partially controlled by the gNB-CU 403. One gNB-DU 404 supports one or more cells. One cell is supported by one gNB-DU 404. The gNB-DU 404 terminates the F1 interface connected to the gNB-CU 403.

[0105] One gNB-DU 404 is connected to one gNB-CU 403 via the F1 interface. NG, Xn, and F1 are logical interfaces. The Xn-C interface interconnects the gNB-CU 403 of different gNBs 402. The gNB 402 may also include a gNB-CU control plane (gNB-CU-CP), multiple gNB-CU user planes (gNB-CU-UP), and multiple gNB-DUs. Figure 4B It is described in more detail in .

[0106] It should be noted that NG-RAN may also include a group of ng-eNBs, and the ng-eNBs may include ng-eNB-CU and one or more ng-eNB-DUs. The ng-eNB-CU and ng-eNB-DU are connected via the W1 interface.

[0107] Figure 4BThe architecture of separation of control plane and user plane (i.e., gNB-CU-CP and gNB-CU-UP) of gNB-CU 403 is illustrated. The gNB-CU-CP 405 is a logical node that hosts the control plane portion of the RRC and PDCP protocols of the gNB-CU 403 for en-gNB or gNB 402. The gNB-CU-CP 405 terminates the E1 interface connected to the gNB-CU-UP 406 and the F1-C interface connected to the gNB-DU 404. The gNB-CU-UP 406 is a logical node that hosts the user plane portion of the PDCP protocol of the gNB-CU 403 for en-gNB, and the user plane portion of the PDCP protocol and SDAP protocol of the gNB-CU 403 for gNB 402. The gNB-CU-UP 406 terminates the E1 interface connected to the gNB-CU-CP 405 and the F1-U interface connected to the gNB-DU 404. The gNB-CU-UP 406 can be connected to one gNB-CU-CP 405, to multiple gNB-CU-UPs 406 and multiple gNB-DUs 404 under the control of the same gNB-CU-CP 405.

[0108] In some embodiments, the gNB-CU-CP 405 is associated with a processor and a memory. The memory includes computer program code to enable the gNB supporting the functions of the gNB-CU-CP 405 to perform the following operations according to the referenced Figure 7 The method described performs the processing.

[0109] The following description may provide further details of alternatives, modifications and differences: for example, the gNB may include a node that provides NR user plane and control plane protocol terminations towards the UE and is connected to the 5GC via an NG interface, for example, in accordance with 3GPP TS38.300 V17.0.0, which is incorporated herein by reference.

[0110] The gNB Central Unit (gNB-CU) includes, for example, logical nodes, hosts, for example, RRC, SDAP and PDCP protocols for gNB or RRC and PDCP protocols for en-gNB, and can control the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DU. The gNB Distributed Unit (gNB-DU) includes, for example, logical nodes, hosts, for example, RLC, MAC and PHY layers for gNB or en-gNB, and its operation is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0111] The gNB-CU-control plane (gNB-CU-CP) comprises, for example, a logical node, hosting the control plane portion of, for example, RRC and PDCP protocols for an en-gNB or gNB-CU. The gNB-CU-CP terminates the E1 interface connected to the gNB-CU-UP, and the F1-C interface connected to the gNB-DU. The gNB-CU-user plane (gNB-CU-UP) comprises, for example, a logical node, hosting the user plane portion of, for example, the PDCP protocol for the gNB-CU of the en-gNB, and the user plane portion of the PDCP protocol and the SDAP protocol for the gNB-CU of the gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP and the F1-U interface connected to the gNB-DU, for example according to 3GPP TS 38.401 V17.0.0, section 3.1, which is incorporated herein by reference.

[0112] There may be different functional splits between the central unit and the distributed units, such as the so-called options: Option 1 (Class 1A split), where the functional split is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, physical layer, and RF are located in the distributed units. Option 2 (Class 3C split), where the functional split is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, physical layer, and RF are located in the distributed units. Option 3 (RLC internal split), where low RLC (partial functions of RLC), MAC, physical layer, and RF are located in the distributed units. PDCP and high RLC (another part of the functions of RLC) are located in the central unit. Option 4 (RLC-MAC split), where MAC, physical layer, and RF are located in the distributed units. PDCP and RLC are located in the central unit. Or other options, such as according to 3GPP TR38.801 V14.0.0, Section 11, which is incorporated herein by reference.

[0113] gNB supports different protocol layers, such as Layer 1 (L1) - Physical Layer. Layer 2 (L2) of NR is divided into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP). The physical layer can provide transport channels to the MAC sublayer; the MAC sublayer can provide logical channels to the RLC sublayer; the RLC sublayer can provide RLC channels to the PDCP sublayer; the PDCP sublayer can provide radio bearers to the SDAP sublayer, and the SDAP sublayer can provide QoS flows to the 5GC. Control channels include, for example, BCCH, PCCH. Layer 3 (L3) includes, for example, Radio Resource Control (RRC), for example according to 3GPP TS38.300 V17.0.0, Section 6, which is incorporated herein by reference.

[0114] A RAN (Radio Access Network) node or network node (e.g., a gNB, a base station, a gNB-CU, or a gNB-DU) or a portion thereof may be implemented using, for example, a device having at least one processor and / or at least one memory having computer-readable instructions (computer programs) configured to support and / or provide and / or process CU and / or DU related functions and / or features, and / or at least one protocol (sub) layer of a RAN (Radio Access Network), such as layer 2 and / or layer 3.

[0115] The gNB-CU and gNB-DU parts may be, for example, co-located or physically separated. The gNB-DU may be even further partitioned, for example into two parts, for example one part including the processing equipment and one part including the antenna. The Central Unit (CU) may also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN or a part thereof. The Distributed Unit (DU) may also be referred to as RRH / RRU / RE / RU, or a part thereof. The gNB-DU supports one or more cells and may thus be used as a serving cell for, for example, a User Equipment (UE).

[0116] User equipment (UE) may include a wireless or mobile device, a device with a wireless interface that interacts with a RAN (radio access network), a smartphone, a vehicle-mounted device, an IoT device, an M2M device, or other. Such a UE or device may include: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to perform at least certain operations, such as an RRC connection with the RAN. For example, the UE is configured to generate a message (e.g., including a cell ID), which is sent to the RAN via the wireless (e.g., arrives at a serving cell and communicates with the serving cell). The UE can generate, send, and receive RRC messages containing one or more RRC PDUs (packet data units).

[0117] The UE may have different states (e.g., according to 3GPP TS 38.331 V17.0.0, Sections 4.2.1 and 4.4, which is incorporated herein by reference). For example, when an RRC connection is established, the UE is either in an RRC_CONNECTED state or in an RRC_INACTIVE state. In the RRC_CONNECTED state, the UE may store an AS context, transmit unicast data to / from the UE, monitor a control channel associated with a shared data channel to determine whether data is scheduled for the data channel, provide channel quality and feedback information, and / or perform neighbor cell measurements and measurement reports. The RRC protocol includes, for example, the following main functions: RRC connection control, measurement configuration and reporting, establishing / modifying / releasing measurement configurations (e.g., intra-frequency, inter-frequency, and inter-RAT measurements), setting and releasing measurement gaps and / or measurement reports.

[0118] In reference Figures 5 to 8 Previously, dual connectivity conditional switching with on-time data forwarding was described according to some embodiments of the subject disclosure, providing some background information and aspects related to the subject disclosure.

[0119] For example, the subject disclosure may be incorporated into a network with dual connectivity and conditional handover (CHO). The CHO process was introduced in the 3GPP Release 16 specification to improve the robustness of mobility. In the case of CHO (e.g., as described in 3GPP TS38.300 V17.0.0, Section 9.2.3.4), the network may prepare multiple target cells, where the conditional handover reconfiguration is associated with the CHO execution condition evaluated by the UE. The CHO execution condition refers to the measurement ID configured by the source gNB (associating the measurement object with the reporting configuration). The reporting configuration defines the measurement event that triggers the CHO execution (e.g., measurement event A3 or A5 defined in Sections 5.5.4.4 and 5.5.4.6 of 3GPP TS38.311 V17.0.0). As long as the CHO execution condition is met, the corresponding target configuration is selected and a handover including data forwarding from the source master node to at least the target master node is performed.

[0120] Furthermore, CHO recovery (or in other words, RRC re-establishment using CHO configuration) was introduced in the 3GPP Release 16 specification to reduce the outage time caused by failures for UEs configured with conditional reconfiguration for multiple target cells. The CHO recovery mechanism (e.g., as described in Section 5.3.7.3 of 3GPP TS38.311 V17.0.0) allows a UE that has detected a radio link failure to recover on a cell with a stored CHO configuration. As long as a radio link failure is detected and a CHO configuration for at least one suitable cell is available, the UE selects the corresponding target configuration and performs a handover including data forwarding from a source master node to at least a target master node.

[0121] Currently, the network can perform two types of data forwarding in this process, namely, delayed data forwarding and advanced data forwarding.

[0122] In the example of postponing data forwarding, the CHO process currently defined in the 3GPP standard is as follows. First, the UE is served by the primary cell (PCell) in the source master node (MN) and the primary secondary cell (PSCell) (i.e., the primary cell of the secondary node) in the source secondary node (SN). The UE sends a measurement report to its serving PCell to initiate CHO preparation for the PCell in the target MN. The source PCell prepares the target PCell and sends the CHO preparation together with the CHO execution conditions to the UE in the RRC reconfiguration message. Once the CHO execution conditions for the target PCell are met, the UE detaches from the source PCell, i.e., stops data transmission / reception (TX / RX) to / from the source PCell. The UE then initiates a random access process toward the target PCell. Once the random access process is successfully completed, the target PCell of the target MN notifies the source PCell of the source MN that the handover process is successfully completed. After receiving the handover success indication from the target MN, the source PCell in the source MN initiates data forwarding to the target PCell of the target MN. Similarly, upon receiving an indication from the source MN (eg, SN release request), the source PSCell in the source SN may initiate data forwarding. Once the data forwarding process is completed, the UE will continue to send / receive data with the network.

[0123] Similarly, in the example of early data forwarding, once CHO preparation is completed, the source PCell in the MN and the source PSCell in the source SN can initiate data forwarding towards the target PCell / PSCell.

[0124] Both delayed and advanced data may cause problems. For example, in the case of delayed data forwarding, when the UE detaches from the source PCell, it will stop TX / RX to / from the source PCell and continue its data connection after the data forwarding between the source and target PCell is completed. During this time, the UE experiences an interruption.

[0125] For example, in the case of early data forwarding, for a prepared target cell that the UE has not accessed, data forwarding before the CHO execution conditions are met is futile. In CHO, the time elapsed between CHO preparation and execution toward the target cell may be as long as hundreds of milliseconds, depending on the preparation and execution conditions. During this period of time, the source PCell performs data forwarding toward the prepared target cell. The data received by the target PCell is buffered by the target PCell until the UE successfully completes the CHO execution toward the target PCell. This also means that the target PCell may discard packets sent by the source PCell to the UE after receiving the early SN status transmission message from the source PCell.

[0126] When the same source PCell prepares multiple target PCells, the resource waste problem of advance data forwarding becomes more prominent, that is, the source PCell will forward data in advance to all prepared target PCells because the source PCell does not know which target PCell the UE will perform CHO to. It should be further pointed out that if the PSCell is prepared together with the PCell, the data must also be forwarded to the SN, resulting in further resource waste.

[0127] Therefore, in the case of deferred data forwarding, the UE will experience user data interruption (after CHO is performed) until data forwarding between the source PCell and the target PCell begins. In the case of advanced data forwarding, the source PCell should perform data forwarding to all prepared target cells, which results in significant signaling overhead on the network until the UE performs CHO to one of the prepared cells.

[0128] To address these issues, an additional message sent to the source PCell instructing the UE to stop communicating with the source PCell could be an option for CHO or CHO recovery. However, once the UE decides to handover to the target cell, there is no way to ensure that the radio link between the UE and the source PCell is stable, as the link may not be good enough to send such a message to the source PCell when the UE performs the handover. Therefore, the benefit of doing so is questionable.

[0129] Therefore, a solution of sending a "CHO ​​execution indication" message is proposed, which overcomes the above mentioned problems and does not rely on a stable connection with the source MN. Sending this message to the source MN via the source SN takes advantage of the dual connectivity in which the UE operates to indicate the CHO execution to the MN via a SN with a sufficiently good radio link quality, given that the decision to change the source SN is not made by the network, but CHO execution involves changing the MN.

[0130] When CHO from the source PCell to the target PCell is performed in the presence of active dual connectivity (DC), that is, the UE is served by the source PCell of the source MN and the source PSCell of the source SN, the method and device for dual connectivity conditional switching and / or CHO recovery proposed in this article allow on-time data forwarding from the source PCell (MN) / source PSCell (SN) to the target PCell / PSCell.

[0131] In order to utilize the UE's connection with the MN and the SN, a CHO execution indication is forwarded from the source SN to the source MN, or more generally, is sent to the source MN via the source SN. In addition, when the CHO execution condition is met, the UE does not interrupt the connection with the source SN. The UE sends a CHO execution indication to the source SN, such as a CHO execution condition satisfaction indication or a CHO recovery execution indication. After sending the CHO execution indication to the source SN, the UE disconnects from the source MN (and in some embodiments also disconnects from the source SN), and then the UE initiates CHO execution, such as starting a handover random access procedure with the target MN. The source SN relays the CHO execution condition satisfaction indication to the source MN, and the source MN and the source SN initiate on-time data forwarding towards the target MN / SN.

[0132] Figure 5 A flow chart for a UE to perform dual connectivity conditional switching with on-time data forwarding is presented. The user equipment includes at least one processor and at least one memory, the memory containing computer program code, causing the UE to perform the process described herein. In other words, the UE is configured to perform the process described herein.

[0133] The UE is configured to operate in a dual-connection mode, that is, it can connect to a source base station (also called source MN) as a master node, and a secondary base station (also called source SN or SN). Figure 5 The described process is typically performed during a conditional handover, for example, during preparation for or at the end of a conditional handover from a source MN to a target base station (also referred to as a target MN) that is then connected as a master node. For example, the source MN may have determined - for example, based on measurements performed and reported by the UE in a measurement report - that a conditional handover with one or more target MNs is expected. Thereafter, the source MN may send a CHO request to the one or more target MNs. One or more (or at least some of) the target MNs may have acknowledged the CHO request. In future communication systems, it is also possible to perform a conditional handover with respect to Figure 5 The described process is preceded by other steps.

[0134] Starting from box 501, the UE establishes a connection towards the PCell of the source MN. As shown in box 502, the UE also establishes a connection towards the PSCell of the source SN. For example, after power-on, the UE may first establish a connection towards the PCell of the source MN based on the measurement value. Thereafter, the UE may also establish a connection towards the PSCell of another base station, which is then used as the source SN to apply dual connectivity. Of course, the UE may also establish connections with these two nodes in other orders. For example, the UE may perform an MN switch, thereby retaining the PSCell of the current source SN and establishing a new connection with the PCell of the switching target MN. Therefore, boxes 501 and 502 are required to ensure that the UE operates under dual connectivity, but may be performed in any order or at any time.

[0135] In block 503, the UE receives a transmission indication, which enables the UE to send a CHO execution indication to the source MN via the source SN. The transmission indication may also configure how the UE sends the CHO execution indication to the source MN via the source SN.

[0136] For example, the transmission indication may configure the UE to send a CHO execution indication to the SN via a signaling radio bearer (e.g., SRB3). In this example, the UE sends the CHO execution indication to the SN via SRB3, and the SN relays this information to the source MN. The MN may then initiate on-time data forwarding. In another example, the transmission indication may configure the UE to send the CHO execution indication via a split bearer. In this example, the UE is configured to send a CHO execution condition satisfied indication to the source MN via a SN bearer terminated by the MN.

[0137] The transmission indication may be sent as an RRC message. In an embodiment, the transmission indication may be received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with the source MN. As another network implementation, the RRC message (e.g., RRC reconfiguration) that triggers the dual-connectivity CHO described herein may be used to configure a split SRB or SRB3 bearer to allow the CHO execution indication to be forwarded to the source MN. In an embodiment, the RRC message carrying the transmission indication may also include: a CHO configuration of at least one target PCell of at least one target MN.

[0138] When the UE is configured to send a CHO execution indication to the source MN via the source SN, it will send the CHO execution indication as configured, as shown in block 504. The CHO execution indication may be sent in response to a condition being met, for example, a condition that triggers a regular handover to the target MN, or a condition that reestablishes a cell due to a radio link failure. Finally, as shown in block 505, after sending the CHO execution indication, the UE processes a conditional handover (e.g., regular CHO or CHO recovery) toward the PCell of the target MN.

[0139] In an example embodiment, with respect to applying the method and apparatus for on-time data forwarding proposed in this document in DC-CHO, the UE is further configured to: receive at least one CHO execution condition from a source MN for CHO of at least one target primary cell toward at least one target primary node. The CHO execution condition defines which conditions should be met for performing CHO toward the target MN. If the UE receives multiple CHO execution conditions for multiple target MNs, these CHO execution conditions may be sent to the UE in one message (e.g., an RRC reconfiguration message). Alternatively, the CHO execution conditions may be sent in at least two separate messages. Instead of using an RRC reconfiguration message, other messages at Layer 2 or Layer 1, such as MAC signaling, or the CHO execution conditions may be sent in signal form via a PDCCH.

[0140] In this example embodiment, the UE may also be configured to perform measurements related to at least one received CHO execution condition. For example, the UE may measure specific connection-specific values, such as synchronization signals (SS) and / or channel state information reference signals (CSI-RS) from the source MN and the target MN. Based on the measured values, the UE may determine whether the CHO execution condition of the target MN is met. If so, the UE may send a CHO execution condition satisfaction indication to the source MN via the SN. In one example, the UE may maintain a connection toward the source MN, i.e., the UE may not stop communicating with the source MN when determining that the CHO execution condition is met, but may only stop communicating after the CHO execution condition is sent.

[0141] In response to at least one of the at least one CHO execution conditions being satisfied for the target master node based on the measurement value, the UE may then be configured to: send a CHO execution indication to the source MN via the source SN, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication. The CHO execution condition satisfaction indication includes: an indication that the CHO execution condition is satisfied.

[0142] In one embodiment, the CHO execution condition satisfaction indication includes: measurement values ​​related to the PCell of the source MN and / or the PCell of the target MN that meet the CHO execution condition. For example, the CHO execution condition satisfaction indication includes: UE measurement values ​​related to the source PCell and / or the target PCell that meet the CHO execution condition. In another embodiment, the CHO execution condition satisfaction indication further or alternatively includes: measurement values ​​related to multiple cells measured and available at the user equipment when the CHO execution condition is met. In this example, the measurement value of the PSCell may also be included.

[0143] The CHO execution condition may be included in an RRC message. In one embodiment, the RRC message may be the same RRC message that carries a transmission indication of at least one target MN and / or the CHO condition. Additionally or alternatively, the CHO execution condition satisfaction indication may include an identification of the source MN, for example, to enable the message to be forwarded to the source MN.

[0144] Additionally or alternatively, the UE may be configured via an RRC message to report measurement values ​​associated with a plurality of cells measured and available at the user equipment when the CHO execution condition is met as described above. Additionally or alternatively, the measurement configuration configures the UE to report measurement values ​​associated with a primary cell of a source SN that meets the CHO execution condition as described above, and / or a primary cell of a target SN.

[0145] In another example embodiment of the method and apparatus for applying the on-time data forwarding proposed in this document in DC-CHO, the UE may be configured to: in response to determining a radio link failure associated with a connection to a primary cell of a source primary node, send a CHO execution indication toward the source primary node via a source secondary node. In this example, the CHO execution indication includes: a CHO recovery execution indication. As will be appreciated by the skilled person, in this example, the general process of sending a message to the source MN via the source SN to ensure on-time forwarding of data is largely the same as the process in another example, wherein the CHO execution indication includes a CHO execution condition satisfaction indication. These two embodiments may be implemented together in the UE, or may be implemented separately.

[0146] In an example of a CHO recovery embodiment, the UE may be configured to: in response to determining that a radio link quality associated with a connection toward a primary cell of a source primary node begins to degrade according to at least one criterion, send a measurement value associated with at least one potential target primary cell of at least one potential target primary node toward the source primary node via the source secondary node. The criterion may include a running timer related to radio link failure detection, for example, the timer is below a threshold, or an out-of-sync indication is received from a lower layer.

[0147] The UE may be configured to report the measurement values ​​via an RRC message, for example, an RRC message for configuring the UE for CHO (particularly CHO recovery). For example, an RRC message (e.g., an RRC reconfiguration message) may include a measurement configuration that configures the UE to report, when the radio link quality associated with the connection toward the primary cell of the source base station begins to degrade, measurement values ​​associated with at least one potential primary cell of the target base station, and / or at least one potential primary and secondary cell of the secondary base station, for example, together with an indication that the CHO execution condition is satisfied, or in another message. These measurement values ​​enable on-time data forwarding for CHO recovery.

[0148] For example, before detecting a radio link failure on the source MN (e.g., when a timer for radio link failure detection (e.g., timer T310) is running or an out-of-sync indication is received from a lower layer), the UE may indicate the best target PCell (with the highest measurement value) to the source SN, for example, using a CHO execution condition satisfaction indication, and the source SN relays this information to the source MN. Using this information, the source MN and the source SN may start forwarding data to potential target cells, from which the UE may select a cell for CHO recovery (triggered after failure detection).

[0149] After sending the CHO execution indication via the SN, the UE may terminate the communication with the source MN and start the handover random access procedure with the target MN. Therefore, the UE may notify the source MN via the SN that it will start the CHO procedure with the target MN while still communicating with the source MN. This enables data transmission to be completed before the UE stops communicating with the source MN and starts random access with the target MN. In addition, this enables the source MN to know when and to which target MN to forward data during the handover. In addition, since the CHO execution indication is sent via the SN, the source MN will receive information about the CHO execution indication even if the connection quality with the source MN is not sufficient for direct transmission.

[0150] The UE may also include components for performing the processes described herein. For example, the UE may include: components for establishing a connection to a primary cell toward a source primary node, and components for establishing a connection to a primary and secondary cell toward a source secondary node. The UE may further include: components for receiving a transmission indication from the source primary node, wherein the transmission indication enables the user equipment to send a CHO execution indication toward the source primary node via the source secondary node, and components for sending a CHO execution indication toward the source primary node via the source secondary node. Finally, the UE may include: components for processing a CHO of a primary cell toward a target primary node. Components for other processes described herein may also be provided.

[0151] Figure 6 A flow chart of dual connectivity conditional switching with on-time data forwarding performed by a source MN is presented. The source MN includes at least one processor and at least one memory, the memory containing computer program code, so that the source MN performs the process described herein. In other words, the source MN is configured to perform the process described herein.

[0152] The source MN is connected to the UE as the master node, and the UE is configured to operate in dual connectivity and is configured to perform during CHO Figure 6 For example, when executing Figure 6Prior to the process of conditional handover, the source MN may have determined (e.g. based on measurements performed and reported by the UE in a measurement report) that a conditional handover with one or more target MNs is expected. Thereafter, the source MN may send a CHO request to the one or more target MNs based on the information provided in the measurement report. Then, one or more (or at least some) of the target MNs may have confirmed the CHO request. It should be noted that in future communication systems, conditional handover preparation may include the following steps: Figure 6 A different process is performed before the process described.

[0153] Starting from block 601, the source MN sends a transmission indication to the UE, wherein the transmission indication enables the user equipment to send a CHO execution indication to the source MN via the source SN. The transmission indication may also configure the UE as to how to send the CHO execution indication to the source MN via the source SN.

[0154] For example, the transmission indication may configure the UE to send a CHO execution indication to the SN via a signaling radio bearer (e.g., SRB3). In this example, the UE sends the CHO execution indication to the SN via SRB3, and the SN relays this information to the source MN. The MN may then initiate on-time data forwarding. In another example, the transmission indication may configure the UE to send the CHO execution indication via a split bearer. In this example, the UE is configured to send a CHO execution condition satisfied indication to the source MN via a SN bearer terminated by the MN.

[0155] The transmission indication may be sent as an RRC message. In an embodiment, the transmission indication may be received as part of a radio resource control RRC reconfiguration message exchanged during connection establishment with the source MN. As another network implementation, the RRC message (e.g., RRC reconfiguration) that triggers the dual-connectivity CHO described herein may be used to configure a split SRB or SRB3 bearer to allow the CHO execution indication to be forwarded to the source MN. In an embodiment, the RRC message carrying the transmission indication may also include: CHO configuration of at least one target PCell of at least one target MN.

[0156] When the UE is configured to transmit a CHO execution indication to the source MN via the source SN, the source MN receives the CHO execution indication from the SN. In addition, as shown in block 602, the source MN initiates data forwarding or general CHO towards the primary cell of the target MN in response to receiving the CHO execution indication from the source SN.

[0157] In an example embodiment of the method and apparatus for applying the on-time data forwarding proposed in this document in DC-CHO, the source MN is further configured to: send at least one CHO execution condition to the UE for CHO of at least one target primary cell toward at least one target primary node. The CHO execution condition defines which condition should be met for performing CHO toward the target MN. If the UE receives multiple CHO execution conditions for multiple target MNs, these CHO execution conditions may be sent to the UE in one message (e.g., an RRC reconfiguration message). Alternatively, the CHO execution conditions may be sent in at least two separate messages. Instead of using an RRC reconfiguration message, other messages at Layer 2 or Layer 1, such as MAC signaling, or signaling the CHO execution conditions via PDCCH may be used.

[0158] In this example embodiment, the source MN may also configure the UE to perform measurements related to at least one received CHO execution condition. For example, the UE may be configured to measure specific connection-specific values, such as synchronization signals (SS) and / or channel state information reference signals (CSI-RS) from the source MN and the target MN. Based on the measured values, the UE may determine whether the CHO execution condition of the target MN is met. If so, the source MN may receive an indication of the CHO execution condition being met via the SN. In one example, the UE may maintain a connection toward the source MN, i.e., the UE does not stop communicating with the source MN when determining that the CHO execution condition is met, but only stops communicating after sending the CHO execution condition.

[0159] In addition, the source MN may be configured to: receive a CHO execution indication from the source MN via the source SN, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication. The CHO execution condition satisfaction indication includes an indication that the CHO execution condition is satisfied.

[0160] In one embodiment, the CHO execution condition satisfaction indication includes: measurements related to the PCell of the source MN and / or the PCell of the target MN that meet the CHO execution condition. For example, the CHO execution condition satisfaction indication includes: UE measurement values ​​related to the source PCell and / or the target PCell that meet the CHO execution condition. In another embodiment, the CHO execution condition satisfaction indication further or alternatively includes: measurement values ​​related to multiple cells measured and available at the user equipment when the CHO execution condition is met. In this example, the measurement value of the PSCell may also be included.

[0161] The CHO execution condition may be included in an RRC message. In one embodiment, the RRC message may be the same RRC message that carries a transmission indication of at least one target MN and / or the CHO condition. Additionally or alternatively, the CHO execution condition satisfaction indication may include an identification of the source MN, for example, to enable the message to be forwarded to the source MN.

[0162] Additionally or alternatively, the UE may be configured via an RRC message to: report measurement values ​​associated with a plurality of cells measured and available at the user equipment when the CHO execution condition as described above is met. Additionally or alternatively, the measurement configuration configures the UE to: report measurement values ​​associated with the primary cell of the source SN that meets the CHO execution condition as described above, and / or the primary cell of the target SN.

[0163] In another example embodiment of the method and apparatus for applying the on-time data forwarding proposed in this article in DC-CHO, the source MN may be configured to: in response to determining a radio link failure related to the connection of the primary cell of the source primary node toward the UE side, receive a CHO execution indication toward the source primary node via the source secondary node. In this example, the CHO execution indication includes: a CHO recovery execution indication. As the technician will understand, in this example, the general process of sending a message to the source MN via the source SN to ensure on-time data forwarding is mostly the same as the process in another example, wherein the CHO execution indication includes: a CHO execution condition satisfaction indication. These two embodiments can be implemented together in the UE, or can be implemented separately.

[0164] In one example of a CHO recovery embodiment, the source MN may be configured to: in response to a determination made by the UE that a radio link quality associated with a connection toward a primary cell of a source primary node begins to degrade according to at least one criterion, receive a measurement value associated with at least one potential target primary cell of at least one potential target primary node toward the source primary node via the source secondary node. The criterion may include: involving a running timer for radio link failure detection, for example, the timer being below a threshold, or receiving an out-of-sync indication from a lower layer.

[0165] The source MN may also be configured to receive measurement values ​​in an RRC message, for example, an RRC message for configuring the UE for CHO (particularly CHO recovery). For example, an RRC message (e.g., an RRC reconfiguration message) may include a measurement configuration that configures the UE to report measurement values ​​related to at least one potential primary cell of the target base station, and / or at least one potential primary and secondary cell of the secondary base station, for example, together with an indication that a CHO execution condition is satisfied, or in another message, when the radio link quality related to the connection toward the primary cell of the source base station begins to degrade. These measurement values ​​enable on-time data forwarding for CHO recovery.

[0166] For example, before a radio link failure is detected on the source MN (e.g., when a timer for radio link failure detection (e.g., timer T310) is running, or an out-of-sync indication is received from a lower layer), the source MN may be configured to receive the best target PCell (with the highest measurement value) for the source SN, for example, using a CHO execution condition satisfaction indication, and the source SN then relays this information to the source MN. Using this information, the source MN and the source SN may start forwarding data to potential target cells, from which the UE may select a cell for CHO recovery (triggered after failure detection).

[0167] After receiving the CHO execution indication via the SN, the source MN may terminate the communication with the UE and start data forwarding to at least the target MN. This enables data transmission to be completed before the UE stops communicating with the source MN and starts random access with the target MN. In addition, this enables the source MN to know when and to which target MN data forwarding should occur during handover. In addition, since the CHO execution indication is sent via the SN, the source MN will receive information about the CHO execution indication even if the connection quality with the source MN is not sufficient for direct transmission.

[0168] The source MN may also include components for performing the processes described herein. For example, the primary MN may include: components for sending a transmission indication to a user equipment, wherein the transmission indication enables the user equipment to send a CHO execution indication to the source primary node via the source secondary node, and components for initiating data forwarding toward the primary cell of the target primary node in response to receiving the CHO execution indication from the secondary node. Components for other processes described herein may also be provided.

[0169] Figure 7 A flow chart of dual connectivity conditional switching with on-time data forwarding performed by a network node supporting the gNB-CU-CP functionality is presented.

[0170] The network node supports a central unit control plane (gNB-CU-CP) function or at least one of the layer 3 protocols of the radio access network, and is configured to: support connection with a user equipment operating in a dual connection manner with a primary cell of the network node and a primary and secondary cell of a source secondary node.

[0171] Starting from box 701, the network node, in particular the gNB-CU-CP of the network node, generates a radio resource control (RRC) message including a transmission indication, wherein the transmission indication enables the user equipment to send a CHO execution indication to the network node via the source secondary node. In addition, in box 702, the message including the transmission indication is sent to the user equipment via the gNB-DU. Finally, in response to receiving the CHO execution indication in the RRC message from the source secondary node, the network node is configured to: initiate data forwarding towards the primary cell of the target primary node, as shown in box 703. As the skilled person will appreciate, the embodiments described with respect to the source MN may also be applicable to Figure 7 network nodes.

[0172] Figure 8 An overall message flow diagram of an embodiment of dual connectivity conditional handover with on-time data forwarding is presented, wherein a CHO execution indication includes a CHO execution condition satisfied indication. The message flow diagram describes a UE 801, a source MN 802, a source SN 803, a target MN 804, a UPF 805, and an AMF 806 acting during CHO according to the present disclosure.

[0173] In numeral 1, when the CHO preparation condition of the target PCell is satisfied, UE 801 sends a measurement report to the source PCell of the source MN 802. In numeral 2, the source PCell of the source MN 802 sends a CHO request to the target PCell of the target MN 804. In numeral 3, the target PCell accepts the CHO preparation request and replies to the source PCell with a CHO request confirmation message. As will be appreciated by the skilled person, the processes of numerals 1 to 3 may also be different, but the general concept of the following process is not changed.

[0174] At number 4, the source PCell configures the CHO preparation configuration of the target PCell, together with the CHO execution condition of the target PCell, to the UE 801. In some embodiments, the UE 801 is therefore further configured to report the CHO execution condition satisfaction indication to the source MN 802 via the source SN 803. Additionally or alternatively, when the radio link quality associated with the connection toward the PCell of the source MN 802 begins to degrade (e.g., an out-of-sync indication is received from the lower layer, or the timer T310 has been started or exceeds a certain threshold), the UE 801 may be configured to report the measurement values ​​of the strongest target PCell and PSCell to the source SN 803. The source SN 803 forwards the measurement report received from the UE 801 back to the source MN 802.

[0175] At number 5, UE 801 starts monitoring the CHO execution condition towards the target PCell. Once the CHO execution condition is met, UE 801 continues to TX / RX to / from the source PCell. At number 6, UE 801 sends a CHO execution condition satisfaction indication via the link between UE 801 and source SN 803. In some embodiments, the CHO execution condition satisfaction indication includes the source PCell and the target PCell that satisfy the CHO execution condition. In another embodiment, the CHO execution condition satisfaction indication includes: measurement values ​​related to the cells configured with the source PCell, such as those to be reported at number 4. In some embodiments, the CHO execution condition satisfaction indication includes: UE measurement values ​​related to all cells measured at UE 801 and available when the CHO execution condition is met.

[0176] At number 7, the source SN 803 relays the CHO execution condition satisfaction indication to the source MN 802. In one embodiment, the UE sends the CHO execution condition satisfaction indication to the source SN 803 via SRB3. In this case, the source SN 803 forwards this message to the source MN 802 via an explicit message. In another alternative, the UE sends the CHO execution condition satisfaction indication to the source MN 802 via a split bearer. In this case, the source SN 803 does not need to send an explicit message to the source MN 802 because the message will be carried via the split SRB between the source MN 802 and the source SN 803.

[0177] The manner in which UE 801 should communicate the CHO execution condition satisfaction indication may be specified by the source MN 802 in the RRC reconfiguration message (at number 4). If measurement values ​​related to the cells configured for the source PCell are provided to the SN, these measurement values ​​are also forwarded to the source MN 802. At number 6, upon sending the CHO execution condition satisfaction indication to the network, the UE 801 stops TX / RX to / from the source node. At number 9, upon receiving the CHO execution condition satisfaction indication from the UE 801 via the source SN 803, the source PCell and the source PSCell initiate data forwarding towards the target PCell. The source PCell / PSCell may decide to start forwarding data to more than one node based on the cell-related measurement values ​​provided by the UE 801 in step 6 and relayed to the MN in number 7.

[0178] Numbers 10 to 14 relate to data forwarding between the source PCell / source PSCell and the target PCell, such as known from NR 3GPP standard release 17. Numbers 15 to 19 relate to random access procedures, such as known from NR 3GPP standard release 16. The handover success and path switching functions in numbers 18 and 19 are performed in parallel with the on-time data forwarding (numbers 9 to 14) because they are independent processes. As the skilled person will understand, the processes of numbers 10 to 14 may also be different, but do not change the general concept of the previous processes described with respect to numbers 4 to 9.

[0179] Once the CHO execution is successfully completed, ie, a HO success message is sent from the target PCell to the source PCell, the target PCell can initiate a data session between the UE 801 and the target PCell, because the data forwarding has been performed on time.

[0180] Fig. 9 An overall message flow diagram of an embodiment of dual connectivity conditional handover with on-time data forwarding is presented, wherein the CHO execution indication includes a CHO recovery indication. The message flow diagram describes a UE 901, a source MN 902, a source SN 903, a target MN 904, a UPF 905, and an AMF 906 acting during CHO according to the present disclosure.

[0181] Numbers 1 to 4 correspond to Figure 8 At number 5, UE 901 does not detect that the CHO condition is met, but identifies a radio link failure associated with the connection toward the primary cell of source MN 904. In this example, at numbers 6 and 7, UE 901 selects a suitable CHO configuration for target MN 904 and notifies source MN 902 of this decision via source SN 903. Numbers 8 to 19 again correspond to Figure 8 .

[0182] In the case where the source MN or SN immediately forwards the user plane packets to the target MN / SN after the CHO execution conditions are met or a decision on CHO recovery has been made, the proposed solution prevents the UE from experiencing interruption time due to delayed data forwarding. In addition, since the source MN / SN knows when data forwarding is required (e.g., on schedule), the solution does not introduce any overhead caused by early data forwarding.

[0183] It should be understood that the apparatus described herein may include or be coupled to other units or modules, such as a radio component or a radio head, for use in or for sending and / or receiving. Although the apparatus is described as one entity, different modules and memories may be implemented in one or more physical or logical entities.

[0184] It should be noted that although embodiments related to LTE and 5G NR have been described, similar principles can also be applied to other networks and communication systems that need to perform fast connection reestablishment. Therefore, although certain embodiments are described above by way of example with reference to certain example architectures of wireless networks, technologies and standards, in addition to the embodiments illustrated and described herein, the embodiments can also be applied to any other suitable form of communication system.

[0185] It is also noted herein that while the above describes example embodiments, there are several variations and modifications that may be made to the disclosed solution without departing from the scope of the subject disclosure.

[0186] In general, the various example embodiments may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects of the subject disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device, but the subject disclosure is not limited thereto. Although various aspects of the subject disclosure may be illustrated and described with block diagrams, flow charts, or using some other graphical representation, it is well known that the blocks, devices, systems, techniques, or methods described herein may be implemented with hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof, as non-limiting examples.

[0187] The example embodiments disclosed in the subject matter may be implemented by computer software executable by a data processor (e.g., a processor entity) of a mobile device, or may be implemented by hardware or by a combination of software and hardware. Computer software or programs, also referred to as program products, include software routines, applets, and / or macros that may be stored in any device-readable data storage medium, and they include program instructions for performing specific tasks. A computer program product may include one or more computer executable components that are configured to perform an embodiment when the program is run. One or more computer executable components may be at least one software code or a portion thereof.

[0188] Also, it should be noted at this point that any box of the logic flow in the figure may represent program steps, or interconnected logic circuits, boxes and functions, or a combination of program steps and logic circuits, boxes and functions. The software may be stored on such physical media as memory chips or memory blocks implemented within a processor, magnetic media (such as hard disks or floppy disks), and optical media (such as DVDs and their data variants CDs). Physical media are non-transitory media.

[0189] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be of any type suitable for the local technical environment and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an FPGA, a gate-level circuit, and a processor based on a multi-core processor architecture, as non-limiting examples.

[0190] Example embodiments of the subject disclosure may be implemented in various components such as integrated circuit modules. The design of integrated circuits is essentially a highly automated process. Complex and powerful software tools are available to convert logic-level designs into semiconductor circuit designs that are ready to be etched and formed on semiconductor substrates.

[0191] The above description provides a comprehensive and detailed description of the exemplary embodiments of the subject disclosure in the form of non-limiting examples. However, from the above description, when read in conjunction with the accompanying drawings and the appended claims, various modifications and adjustments will become apparent to those skilled in the relevant art. However, all such and similar modifications to the teachings of the present disclosure will still fall within the scope of the subject disclosure defined in the appended claims. In fact, there are other embodiments including a combination of one or more embodiments with any other embodiment discussed above.

Claims

1. A user equipment, configured to support operation with dual connectivity in at least one radio access network RAN, and configured to support conditional handover CHO, the user equipment comprising: at least one processor, and at least one memory including computer program code which, when executed together with the at least one processor, causes the user equipment to: Establishing a connection towards the primary cell of the source primary node; Establishing a connection between the primary and secondary cells towards the source secondary node; receiving a transmission indication from the source primary node, wherein the transmission indication enables the user equipment to send a CHO execution indication towards the source primary node via the source secondary node; sending the CHO execution indication toward the source primary node via the source secondary node; and Process the CHO of the primary cell towards the target primary node. 2 . The user equipment according to claim 1 , wherein the transmission indication further configures how the user equipment sends the CHO execution indication towards the source primary node via the source secondary node.

3. The user equipment according to claim 2, wherein the user equipment is configured to send the CHO execution indication towards the source secondary node via at least one of a signal radio bearer or a split bearer terminated at the source primary node.

4. The user equipment according to any of the preceding claims, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message.

5. The user equipment according to any one of the preceding claims, wherein the transmission indication is received as part of a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message further comprising: A CHO configuration of at least one target primary cell of at least one target primary node.

6. A user equipment according to any preceding claim, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message exchanged during establishment of the connection with the source primary node.

7. The user equipment according to any one of the preceding claims, further configured to: receiving, from the source master node, at least one CHO execution condition for CHO towards at least one target primary cell of at least one target master node; performing measurements related to the received at least one CHO execution condition; as well as In response to at least one of the at least one CHO execution condition being satisfied for the target primary node based on the measurement, sending the CHO execution indication toward the source primary node via the source secondary node, wherein the CHO execution indication comprises: a CHO execution condition satisfied indication.

8. The user equipment according to claim 7, further configured to: When sending the CHO execution condition satisfaction indication, maintaining the connection toward the primary and secondary cells of at least the source secondary node to continue data transmission and reception; and After sending the CHO execution condition satisfaction indication, terminating the connection toward the primary cell of the source primary node to stop data transmission and reception.

9. The user equipment according to claim 7 or 8, wherein the CHO execution condition satisfaction indication comprises: The measurement values ​​related to the primary cell of the source master node and the primary cell of the target master node that satisfy the CHO execution condition.

10. The user equipment according to any one of claims 7 to 9, wherein the CHO execution condition satisfaction indication further comprises: Measurement values ​​associated with a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

11. The user equipment according to any one of claims 7 to 10, wherein the CHO execution condition is received as a part of a radio resource control (RRC) reconfiguration message.

12. The user equipment according to any one of claims 7 to 11, wherein the CHO execution condition is included in the same message as at least one of the CHO transmission indication of the at least one target primary cell of the at least one target primary node, or the CHO configuration.

13. The user equipment according to any one of claims 7 to 12, wherein the message used to send the CHO execution condition satisfaction indication further comprises: The identifier of the source master node.

14. The user equipment according to any one of the preceding claims, further configured to: In response to a determination of a radio link failure associated with the connection toward the primary cell of the source primary node, the CHO execution indication is sent toward the source primary node via the source secondary node, wherein the CHO execution indication comprises a CHO recovery execution indication.

15. The user equipment according to any one of the preceding claims, further configured to: In response to determining according to at least one criterion that a radio link quality associated with the connection toward the primary cell of the source primary node begins to degrade, sending the CHO execution indication toward the source primary node via the source secondary node, wherein the CHO execution indication comprises: Measurement values ​​associated with at least one potential target primary cell of at least one potential target primary node towards the source primary node via the source secondary node.

16. The user equipment according to claim 15, wherein the at least one criterion comprises at least one threshold value, and a radio link quality degradation below the threshold value is determined when a timer for radio link failure detection is running or after receiving an out-of-sync indication from a lower layer.

17. A source master node, configured to support establishing a connection toward a user equipment, the user equipment being configured to support operating with a primary cell of the source master node and a primary and secondary cell of a source secondary node in dual connectivity, and supporting conditional handover (CHO), the source master node comprising: at least one processor, and at least one memory including computer program code, which when executed together with the at least one processor, causes the source master node to: sending a transmission indication to the user equipment, wherein the transmission indication: enables the user equipment to send a CHO execution indication toward the source primary node via the source secondary node; and In response to receiving the CHO execution indication from the source secondary node, data forwarding towards a primary cell of a target primary node is initiated.

18. The source master node according to claim 17, wherein the transmission indication further configures how the user equipment sends the CHO execution indication towards the source master node via the source secondary node.

19. The source primary node according to claim 18, wherein the transmission indication: configures the user equipment to send the CHO execution indication toward the source secondary node via at least one of a signal radio bearer or a split bearer terminated at the source primary node.

20. The source master node according to any one of claims 17 to 19, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message.

21. The source master node according to any one of claims 17 to 20, wherein the transmission indication is received as part of a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message further comprising: A CHO configuration of at least one target primary cell of at least one target primary node.

22. The source master node according to any one of claims 17 to 21, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message exchanged during establishment of the connection with the source master node.

23. The source master node according to any one of claims 17 to 22, further configured to: sending at least one CHO execution condition towards at least one target primary cell of at least one target primary node for conditional handover; and receiving the CHO execution indication from the source secondary node, wherein the CHO execution indication comprises: CHO executes the condition satisfied indication.

24. The source master node according to claim 23, further configured to: In response to receiving the CHO execution condition satisfaction indication, terminating the connection toward the user equipment to stop data transmission and reception.

25. The source master node according to claim 23 or 24, wherein the CHO execution condition satisfaction indication comprises: The measurement values ​​related to the primary cell of the source master node and the primary cell of the target master node that satisfy the CHO execution condition.

26. The source master node according to any one of claims 23 to 25, wherein the CHO execution condition satisfaction indication further comprises: Measurement values ​​associated with a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

27. The source master node according to any one of claims 23 to 26, wherein the CHO execution condition is sent as a part of a Radio Resource Control (RRC) message.

28. The source master node according to any one of claims 23 to 27, wherein the CHO execution condition is included in the same message as at least one of the CHO transmission indication or CHO configuration of the at least one target primary cell of the at least one target master node.

29. The source master node according to any one of claims 23 to 28, wherein the message used to send the CHO execution condition satisfaction indication further comprises: The identifier of the source master node.

30. The source master node according to any one of claims 17 to 29, further configured to: receiving the CHO execution indication from the source secondary node, wherein the CHO execution indication comprises: A CHO recovery execution indication is sent in response to the user equipment determining a radio link failure associated with the connection towards the primary cell of the source primary node.

31. The source master node according to any one of claims 17 to 30, further configured to: receiving the CHO execution indication via the source secondary node, wherein the CHO execution indication comprises: A measurement value from the source secondary node associated with at least one potential target primary cell of at least one potential target primary node, wherein the measurement value is sent in response to the user equipment determining according to at least one criterion that the radio link quality associated with the connection toward the primary cell of the source primary node begins to deteriorate.

32. The source master node according to claim 31, wherein the at least one criterion includes at least one threshold, and a radio link quality degradation below the threshold is determined when a timer for radio link failure detection runs or after receiving an out-of-sync indication from a lower layer.

33. A network node supporting at least one of a central unit control plane function or a layer 3 protocol of a radio access network, configured to support a connection with a user equipment operating with a primary cell of the network node and a primary and secondary cell of a source secondary node in dual connectivity, and configured for conditional handover (CHO), the network node comprising: at least one processor, and at least one memory including computer program code which, when executed together with the at least one processor, causes the network node to: generating a radio resource control, RRC, message comprising a transmission indication, wherein the transmission indication enables the user equipment to send a CHO execution indication towards the network node via the source secondary node; Sending the radio resource control RRC message including the transmission indication to the user equipment; as well as In response to receiving the CHO execution indication in a radio resource control (RRC) message from the source secondary node, data forwarding towards a primary cell of a target primary node is initiated.

34. The network node according to claim 33, wherein the transmission indication further configures how the user equipment sends the CHO execution indication towards the network node via the source secondary node.

35. The network node according to claim 30, wherein the transmission indication configures: the user equipment to send the CHO execution indication towards the source secondary node via at least one of a signaling radio bearer or a split bearer terminated at the network node.

36. The network node according to any one of claims 33 to 35, wherein the radio resource control (RRC) message including the transmission indication further comprises: A CHO configuration of at least one target primary cell of at least one target primary node.

37. A network node according to any of claims 33 to 36, wherein the transmission indication is sent during establishment of the connection with the network node.

38. The network node according to any one of claims 33 to 37, further being caused to: Generate a radio resource control RRC message, the RRC message including: at least one CHO execution condition for conditional handover towards at least one target primary cell of at least one target primary node; sending the radio resource control RRC message including the at least one CHO execution condition to the user equipment; as well as The CHO execution indication in a radio resource control (RRC) message is received from the source secondary node, wherein the CHO execution indication comprises: a CHO execution condition satisfaction indication.

39. The network node according to claim 38, further caused to: In response to receiving the CHO execution condition satisfaction indication, terminating the connection toward the user equipment to stop data transmission and reception.

40. The network node according to claim 38 or 39, wherein the CHO execution condition satisfaction indication comprises: and measurement values ​​related to the primary cell of the network node that meets the CHO execution condition and the primary cell of the target primary node.

41. The network node according to any one of claims 38 to 40, wherein the CHO execution condition satisfaction indication further comprises: Measurement values ​​associated with a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

42. The network node according to any one of claims 38 to 41, wherein the CHO execution condition is included in the same message as at least one of the CHO transmission indication or the CHO configuration of the at least one target primary cell of the at least one target primary node.

43. The network node according to any one of claims 38 to 42, wherein the message for sending the CHO execution condition satisfaction indication further comprises: The identifier of the source master node.

44. The network node according to any one of claims 33 to 43, further configured to: Receive the CHO execution indication from the source secondary node, wherein the CHO execution indication comprises: A CHO recovery execution indication is sent in response to the user equipment determining a radio link failure associated with the connection towards the primary cell of the network node.

45. The network node according to any one of claims 33 to 44, further configured to: Receiving, from the source secondary node, measurement values ​​associated with at least one potential target primary cell of at least one potential target primary node, wherein the measurement values ​​are sent in response to the user equipment determining, according to at least one criterion, that a radio link quality associated with the connection towards the primary cell of the network node begins to degrade.

46. ​​The network node of claim 45, wherein the at least one criterion comprises at least one threshold, and a degradation of the radio link quality below the threshold is determined when a timer for radio link failure detection runs or after receiving an out-of-sync indication from a lower layer.

47. A conditional handover (CHO) method performed by a user equipment, the user equipment being configured to: operate with dual connectivity in at least one radio access network RAN, the method comprising: Establishing a connection towards the primary cell of the source primary node; Establishing a connection between the primary and secondary cells towards the source secondary node; receiving a transmission indication from the source primary node, wherein the transmission indication enables the user equipment to send a CHO execution indication towards the source primary node via the source secondary node; sending the CHO execution indication toward the source primary node via the source secondary node; and Process the CHO of the primary cell towards the target primary node.

48. The method according to claim 47, wherein the transmission indication further configures: how the user equipment sends the CHO execution indication towards the source primary node via the source secondary node.

49. The method of claim 48, further comprising: The CHO execution indication is sent towards the source secondary node via at least one of a signaling radio bearer or a split bearer terminated at the source primary node.

50. The method according to any one of claims 47 to 49, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message.

51. The method according to any one of claims 47 to 50, wherein the transmission indication is received as part of a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message further comprising: A CHO configuration of at least one target primary cell of at least one target primary node.

52. A method according to any one of claims 47 to 51, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message exchanged during establishment of the connection with the source primary node.

53. The method according to any one of claims 47 to 52, further comprising: receiving, from the source master node, at least one CHO execution condition for CHO towards at least one target primary cell of at least one target master node; performing measurements related to the received at least one CHO execution condition; as well as In response to at least one of the at least one CHO execution condition being satisfied for the target master node based on the measurement, sending the CHO execution indication toward the source master node via the source secondary node, wherein the CHO execution indication comprises: a CHO execution condition satisfied indication.

54. The method of claim 53, further comprising: When sending the CHO execution condition satisfaction indication, maintaining the connection toward at least the primary and secondary cells of the source secondary node to continue data transmission and reception; as well as After sending the CHO execution condition satisfaction indication, terminating the connection toward the primary cell of the source primary node to stop data transmission and reception.

55. The method according to claim 53 or 54, wherein the CHO execution condition satisfaction indication comprises: and measurement values ​​associated with the primary cell of the source master node and the primary cell of the target master node that satisfy the CHO execution condition.

56. The method according to any one of claims 53 to 55, wherein the CHO execution condition satisfaction indication further comprises: Measurement values ​​associated with a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

57. The method according to any one of claims 53 to 56, wherein the CHO execution condition is received as part of a Radio Resource Control, RRC, message.

58. The method according to any one of claims 53 to 57, wherein the CHO execution condition is included in the same message as at least one of the CHO transmission indication or the CHO configuration of the at least one target primary cell of the at least one target primary node.

59. The method according to any one of claims 53 to 58, wherein the message used to send the CHO execution condition satisfaction indication further comprises: The identifier of the source master node.

60. The method according to any one of claims 47 to 59, further comprising: In response to a determination of a radio link failure associated with the connection to the primary cell toward the source primary node, the CHO execution indication is sent toward the source primary node via the source secondary node, wherein the CHO execution indication comprises: a CHO recovery execution indication.

61. The method of claim 60, further comprising: In response to determining according to at least one criterion that the radio link quality associated with the connection toward the primary cell of the source primary node begins to decline, measurement values ​​associated with at least one potential target primary cell of at least one potential target primary node are sent toward the source primary node via the source secondary node.

62. The method of claim 61, wherein the at least one criterion comprises at least one threshold, and a degradation of the radio link quality below the threshold is determined when a timer for radio link failure detection runs or after receiving an out-of-sync indication from a lower layer.

63. A method for conditional handover (CHO) performed by a source primary node connected to a user equipment, wherein the user equipment operates with a primary cell of the source primary node and with a primary and secondary cell of a source secondary node in dual connectivity, the method comprising: sending a transmission indication to the user equipment, wherein the transmission indication enables the user equipment to send a CHO execution indication towards the source primary node via the source secondary node; as well as In response to receiving the CHO execution indication from the source secondary node, data forwarding towards a primary cell of a target primary node is initiated.

64. The method of claim 63, wherein the transmission indication further configures how the user equipment sends the CHO execution indication towards the source primary node via the source secondary node.

65. The method of claim 64, wherein the transmission indication configures: the user equipment is configured to send the CHO execution indication toward the source secondary node via at least one of a signal radio bearer or a split bearer terminated at the source primary node.

66. A method according to any one of claims 63 to 65, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message.

67. The method according to any one of claims 63 to 66, wherein the transmission indication is received as part of a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message further comprising: A CHO configuration of at least one target primary cell of at least one target primary node.

68. A method according to any one of claims 63 to 67, wherein the transmission indication is received as part of a Radio Resource Control (RRC) reconfiguration message exchanged during establishment of the connection with the source primary node.

69. The method according to any one of claims 63 to 68, further comprising: sending at least one CHO execution condition for conditional handover towards at least one target primary cell of at least one target primary node; as well as The CHO execution indication is received from the source secondary node, wherein the CHO execution indication comprises: a CHO execution condition satisfaction indication.

70. The method of claim 69, further comprising: In response to receiving the CHO execution condition satisfaction indication, terminating the connection towards the primary cell of the source primary node.

71. The method according to claim 69 or 70, wherein the CHO execution condition satisfaction indication comprises: The measurement values ​​related to the primary cell of the source master node and the primary cell of the target master node that satisfy the CHO execution condition.

72. The method according to any one of claims 69 to 71, wherein the CHO execution condition satisfaction indication further comprises: Measurement values ​​associated with a plurality of cells measured at the user equipment and available when the CHO execution condition is satisfied.

73. The method according to any one of claims 69 to 72, wherein the CHO execution condition is sent as part of a Radio Resource Control (RRC) message.

74. The method according to any one of claims 69 to 73, wherein the CHO execution condition is included in the same message as at least one of the CHO transmission indication or the CHO configuration of the at least one target primary cell of the at least one target primary node.

75. The method according to any one of claims 69 to 74, wherein the message for sending the CHO execution condition satisfaction indication further comprises: The identifier of the source master node.

76. The method of any one of claims 63 to 75, further comprising: The CHO execution indication is received from the source secondary node, wherein the CHO execution indication comprises: a CHO recovery execution indication, wherein the CHO recovery execution indication is sent in response to the user equipment determining a radio link failure associated with the connection toward the primary cell of the source primary node.

77. The method of claim 76, further comprising: Receiving measurement values ​​associated with at least one potential target primary cell of at least one potential target primary node from the source secondary node, wherein the measurement values ​​are sent in response to the user equipment determining, according to at least one criterion, that a radio link quality associated with the connection toward the primary cell of the source primary node begins to degrade.

78. The method of claim 77, wherein the at least one criterion comprises at least one threshold, and a degradation of the radio link quality below the threshold is determined when a timer for radio link failure detection runs or after receiving an out-of-sync indication from a lower layer.

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