Data forwarding for dual connectivity

Abstract

The present subject matter relates to a method comprising: sending, by an apparatus to a user equipment, a message (referred to herein as a reconfiguration message) for conditional switching, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; in response to the transmission of the reconfiguration message, receiving, by the apparatus, from the user equipment, a message indicating at least one particular candidate target secondary node of the candidate target secondary nodes; data forwarding is performed by the apparatus towards the at least one particular candidate target secondary node, and towards a subset of candidate target primary nodes associated with the at least one particular candidate target secondary node.

Description

Technical Field

[0001] Various example embodiments relate to telecommunication systems, and more particularly to data forwarding for implementing handovers and secondary cell changes. Background Art

[0002] The fifth generation of wireless networks (5G) refers to a new generation of radio systems and network architectures. It is expected that 5G will provide higher bit rates and coverage than the current long-term evolution (LTE) system. It is expected that 5G will also increase network scalability to hundreds of thousands of connections. However, it is necessary to improve the communication services provided at these systems, particularly for implementing dual connectivity. Some aspects of dual connectivity have been described in standards, such as TS 36.300, TS 36.423, TS 36.413 for LTE, or TS 38.300, TS 37.340, TS 38.423, etc. for NR. Summary of the invention

[0003] An example embodiment provides a device configured as a master node to serve a user device in a dual connection. The device includes a component. The component is configured to: send a message for conditional switching (referred to herein as a reconfiguration message) to the user device, the reconfiguration message indicating a set of one or more candidate target master nodes and associated candidate target secondary nodes; in response to the sending of the reconfiguration message, receive a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes from the user device; perform data forwarding to at least one specific candidate target secondary node, and to a subset of candidate target master nodes associated with at least one specific candidate target secondary node.

[0004] An example embodiment provides a user equipment that is in dual connection with an apparatus acting as a source primary node and a source secondary node. The user equipment includes a component. The component is configured to: receive a reconfiguration message for conditional switching from the apparatus, the reconfiguration message indicating a condition for conditional switching CHO to a set of candidate target primary nodes (referred to herein as CHO conditions), and another condition for conditional primary and secondary cell change (CPC) to a candidate target secondary node (referred to herein as CPC conditions); evaluate the CHO conditions and the CPC conditions; in response to determining that the CPC conditions are satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, send a message indicating at least one specific candidate target secondary node to the apparatus.

[0005] An example embodiment provides a method. The method includes: a device sends a message for conditional switching (referred to herein as a reconfiguration message) to a user equipment, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; in response to the sending of the reconfiguration message, the device receives a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes from the user equipment; and the device forwards data to the at least one specific candidate target secondary node and to a subset of candidate target primary nodes associated with the at least one specific candidate target secondary node.

[0006] An example embodiment provides a computer program comprising instructions for causing an apparatus to perform at least the following: sending a message for conditional switching (referred to herein as a reconfiguration message) to a user device, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; receiving a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes from the user device in response to the sending of the reconfiguration message; and performing data forwarding to at least one specific candidate target secondary node, and to a subset of candidate target primary nodes associated with the at least one specific candidate target secondary node.

[0007] An example embodiment provides a method. The method includes: receiving a reconfiguration message for conditional switching from the device, the reconfiguration message indicating a condition for conditional switching to a set of candidate target primary nodes (referred to herein as a CHO condition), and another condition for conditional primary and secondary cell change (CPC) to one or more candidate target secondary nodes (referred to herein as a CPC condition); evaluating the CHO condition and the CPC condition; and in response to determining that the CPC condition is satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, sending a message indicating at least one specific candidate target secondary node to the device.

[0008] An example embodiment provides a computer program comprising instructions for causing a user equipment to perform at least the following: receiving a reconfiguration message for conditional switching from an apparatus, the reconfiguration message indicating a condition for conditional switching to a set of candidate target primary nodes (referred to herein as a CHO condition), and another condition for conditional primary-secondary cell change (CPC) to one or more candidate target secondary nodes (referred to herein as a CPC condition); evaluating the CHO condition and the CPC condition; and in response to determining that the CPC condition is satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, sending a message indicating at least one specific candidate target secondary node to the apparatus.

[0009] In one example, at least one specific candidate target secondary node satisfying the CPC condition may be a specific candidate target secondary node. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings are included to provide a further understanding of the examples, and are incorporated into and constitute a part of this specification. In the drawings:

[0011] Figure 1 illustrates a portion of an exemplary radio access network;

[0012] Figure 2 is a schematic diagram of a wireless communication system;

[0013] Figure 3 is a flow chart of a method used in a master node according to an example of the present subject matter;

[0014] Figure 4 is a flow chart of a method used in a user device according to an example of the present subject matter;

[0015] Figure 5 is a flow chart of a method used in a master node according to an example of the present subject matter;

[0016] Figure 6 is a flow chart of a method used in a user device according to an example of the present subject matter;

[0017] Figure 7 is a flow chart of a signaling method for conditional switching according to an example of the present subject matter;

[0018] Figure 8 is a flow chart of a signaling method for conditional switching according to an example of the present subject matter;

[0019] Fig.9A is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment according to an example of the present subject matter;

[0020] Fig. 9B is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment according to an example of the present subject matter;

[0021] Fig. 9C is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment according to an example of the present subject matter;

[0022] Fig.10 is a block diagram illustrating an example of an apparatus according to examples of the present subject matter. DETAILED DESCRIPTION

[0023] In the following description, for the purpose of explanation rather than limitation, specific details are set forth, such as specific architectures, interfaces, techniques, etc., in order to provide a thorough understanding of the examples. However, those skilled in the art will appreciate that the disclosed subject matter can be practiced in other illustrative examples that deviate from these specific details. In some cases, detailed descriptions of well-known devices and / or methods are omitted so as not to obscure the description with unnecessary details.

[0024] A communication system may be provided. The communication system includes nodes such as base stations, each of which may serve user equipment (UE) located within a service geographic area or cell of the node. The communication system may support one or more radio access technologies (RATs). For example, the radio access technology in the radio access technology may be Evolved Universal Terrestrial Radio Access (E-UTRA) or 5G New Radio (NR), but is not limited thereto, as those skilled in the art may apply the subject matter to other communication systems provided with the necessary attributes.

[0025] The communication system can implement dual connectivity. During dual connectivity operation, the user equipment can be coupled to a first node and further coupled to a second node. Therefore, dual connectivity can involve a user equipment and two nodes. One of the two nodes can act as a master node (MN) and the other node can act as a secondary node (SN). The master node and the secondary node can be connected via a network interface, and at least the master node is connected to the core network of the communication system. The nodes of the communication system may include a plurality of nodes configured to operate as a master node and a plurality of nodes configured to operate as secondary nodes during dual connectivity operation. The communication between the two nodes of the communication system can be through an ideal backhaul or a non-ideal backhaul. Dual connectivity can allow the user equipment to consume radio resources provided by the two nodes. In particular, dual connectivity can allow the user equipment to communicate with the two nodes simultaneously by sending data to the two nodes and receiving data from the two nodes in two completely independent streams.

[0026] The service geographic area of ​​the primary node may be referred to as the primary cell. The service geographic area of ​​the secondary node may be referred to as the primary and secondary cells. In one example, two nodes and a user device may communicate with each other via multiple component carriers. For example, the primary node may communicate with the user device via a first set of component carriers, which provide coverage for a first set of cells forming a so-called primary cell group (MCG). The secondary node may communicate with the user device via a second set of component carriers, which provide coverage for a second set of cells forming a so-called secondary cell group (SCG). The cells in the first group of cells used to initiate initial access may be referred to as primary cells (PCells), and the remaining cells may be referred to as secondary cells (SCells). Similarly, the second group of cells includes a primary cell (PSCell) and a secondary cell (SCell), and the primary cell may be understood as a cell for which initial access is initiated under the SCG.

[0027] The nodes of the communication system may include low-power nodes and high-power nodes. The low-power nodes may be configured to transmit with lower power and less processing / hardware capabilities than the high-power nodes. The low-power nodes may include small base stations, micro base stations, micro-base stations, or femto base stations. The low-power nodes may be able to cope with mobile service exposure, especially for hotspot deployments in indoor and outdoor scenarios. For example, the primary node may be a high-power node. For example, the secondary node may be a high-power node or a low-power node.

[0028] The present subject matter can improve dual connection operation to enhance the robustness of mobility in a communication system. To this end, a device can be provided. The device can be configured as a master node in a dual connection involving a user equipment and a secondary node. After the dual connection has been established, the device can be configured as a master node. The user equipment may be referred to as a dual connection user equipment in this article, and the secondary node may be referred to as a serving secondary node. The dual connection user equipment may be served by a device in a primary cell (such as a PCell). The dual connection user equipment may be served by a serving secondary node in a primary and secondary cell (e.g., such as a PSCell).

[0029] The movement of a dual-connected user equipment may trigger a handover of the dual-connected user equipment from a primary cell to a target primary cell served by a target primary node. If performed conditionally, such a handover is referred to as a conditional handover (CHO). The movement of a dual-connected user equipment may trigger a change of a primary secondary cell to a target primary secondary cell served by a target secondary node. If performed conditionally, such a primary secondary cell change may be referred to as a conditional primary secondary cell (PSCell) change (CPC).

[0030] The dual-connection user equipment can be configured to perform cell measurements in a connected mode, an inactive mode, or an idle mode of a primary cell. For example, measuring a cell such as a primary cell can be performed by measuring at least one beam of the cell (e.g., its power). The beam measurement results can be combined (e.g., averaged) to derive the signal quality or cell quality of the cell. The signal quality can be, for example, a reference signal received power (RSRP) or a reference signal received quality (RSRQ) measurement. Cell measurements can be advantageously used to perform a conditional handover (CHO) process. For example, the dual-connection user equipment can be configured to use cell measurements of the primary cell to check whether the initial handover criteria are met or reached. For example, the initial handover criteria may include the conditions of a radio resource management (RRM) event A3. Satisfaction of the initial handover conditions can trigger the dual-connection user equipment to send a measurement report to the device. Based on the measurement report, the device can determine whether a handover is required, and if necessary, the device can select a set of M candidate target master nodes. ……、 For example, a set of M candidate target master nodes in the neighbor list of the target master node, where M ≥ 1. The device may prepare a set of M candidate target master nodes ……、 A set of dual-connected user devices to candidate target master nodes ……、 Alternatively, the device may automatically prepare a set of candidate target master nodes. ……、 A set of dual-connected user devices to candidate target master nodes ……、 The preparation of the set of candidate target master nodes may include providing, by the device, to the set of candidate target master nodes. ……、 Send a switch request. In response, the set of candidate target master nodes ……、 Each i-th (where i is a number between 1 and M) candidate target master node in A handover request confirmation may be sent to the device, wherein the handover request confirmation indicates a switch with the candidate target master node For example, each handover request confirmation may include a link to a candidate target primary node that may be established by the device. and a tunnel endpoint identifier (TEID) of a direct tunnel (eg, a data radio bearer (DRB) tunnel) of the associated candidate target secondary node. Thus, each candidate target secondary node (where j can be any number between 1 and N, where N is the number of candidate target secondary nodes) and n j A subset of ≥1 candidate target master nodes associated, where K j It means n j A list of indexes of candidate target primary nodes. Candidate target secondary nodes With n j A subset of ≥1 candidate target master nodes This means that the candidate target auxiliary node The primary and secondary cells served are at least partially connected to the j A subset of ≥1 candidate target master nodes Each primary cell served overlaps.

[0031] Preparing a set of candidate target master nodes ……、 Afterwards, the apparatus may send a message (referred to herein as a reconfiguration message) to the dual-connection user equipment for the set of candidate target master nodes. ……、 The conditional switch of one candidate target primary node in the set of N candidate target secondary nodes ……、 The primary and secondary cells of one of the candidate target secondary nodes change, where N ≥ M. The set of candidate target primary nodes ……、 Each candidate target primary node in can be associated with the set of candidate target secondary nodes ……、 The reconfiguration message may be provided by dedicated signaling, such as using radio resource control (RRC) reconfiguration.

[0032] The reconfiguration message may include first information indicating a set of candidate target master nodes. ……、 The reconfiguration message may also include a second information indicating a condition for conditional switching of each candidate target primary node in the dual-connection user equipment (referred to herein as a CHO condition) and a configuration (CHO command) that the dual-connection user equipment should apply to the candidate target primary node when its corresponding CHO condition is met. ……、 Another condition of CPC for each node in the (referred to herein as CPC condition) and the configuration to be applied to the candidate target secondary nodes that satisfy the CPC condition.

[0033] Upon receiving the reconfiguration message, the dual-connection user equipment may determine whether the CHO condition is met and whether the CPC condition is met, for example, using the cell measurement of the primary cell and the cell measurement of the primary and secondary cells. Alternatively, the dual-connection user equipment may be configured to automatically check the CHO condition and the CPC condition without relying on the reconfiguration message. In other words, triggering the dual-connection user equipment to check the CHO condition and the CPC condition with the reconfiguration message may be optional. The dual-connection user equipment may repeatedly check the CPC condition and the CHO condition.

[0034] The CPC condition may require that a signal value indicative of a signal received from a candidate target secondary node exceeds another signal value indicative of a signal received from a serving secondary node by at least an offset value within a time to trigger (TTT) interval. ……、 Each candidate target secondary node in is checked individually for CPC condition.

[0035] The CHO condition may require that a signal value indicating a signal received from a candidate target master node exceeds another signal value indicating a signal received from the device by at least an offset value within a TTT interval. Each value of the signal value may be RSRP or RSRQ. The set of candidate target master nodes may be selected by the user equipment ……、 Each candidate target master node in is checked individually for CHO condition.

[0036] At least one candidate target secondary node may satisfy the CPC condition. In one example, a candidate target secondary node may satisfy the CPC condition. If the CPC condition is met before the CHO condition is met, the dual-connection user equipment may send a signal indicating the candidate target secondary node to the device. In one example, the CPC message may also include a CHO measurement performed by the dual-connection user equipment. The CHO measurement may include a set of candidate target master nodes. ……、 Cell measurements of served cells.

[0037] In response to receiving the CPC message, the device may begin sending requests to candidate target secondary nodes. and candidate target secondary nodes A subset of candidate target nodes associated with Alternatively, the device may use CHO measurements to select a subset of candidate target nodes The dual-connected user equipment is most likely to move to this subset. For example, the CHO measurement can be used by the apparatus to predict the moving path of the dual-connected user equipment, wherein the selected subset of the subset of candidate target nodes can be a serving cell close to the moving path. Therefore, the candidate target secondary node can be and performing data forwarding to a selected subset of candidate target master nodes. The data forwarding involves data of the dual-connected user equipment, that is, data forwarding is performed on packets that can be used by (multiple) target nodes to continue serving the dual-connected user equipment. Therefore, the present subject matter can optimize data forwarding because it can be performed on time and only relevant nodes can receive forwarded data. The present subject matter can support data forwarding with candidate SCGs in CHO for conditional PSCell change / addition (CPAC).

[0038] Data forwarding includes forwarding to candidate secondary nodes and to candidate target secondary nodes A subset of associated candidate target master nodes Delivering buffered packets. Data forwarding may also include delivering in-flight packets. In-flight packets may be packets that should be sent to a target node that meets the CHO / CPC condition, but are sent to the device for transmission after switching and before the path switching to the candidate target master node that meets the CHO condition is completed. In addition, the device may send a subset of candidate target master nodes. A sequence number status transfer message is sent indicating the next missed packet in the downlink and uplink.

[0039] If the CHO condition is satisfied by a specific candidate target primary node after the CPC condition is satisfied, the dual-connection user device may stop exchanging data with the device and synchronize to the specific candidate target primary node. The dual-connection user device may detach from the device before synchronizing to the specific candidate target primary node and apply the configuration to the specific candidate target primary node. The dual-connection user device may also synchronize to a candidate target secondary node. For example, if the CPC condition is satisfied by multiple candidate target secondary nodes, synchronization with a candidate target secondary node associated with a specific candidate target primary node may be performed. If multiple candidate target secondary nodes satisfy the CPC condition and are associated with a specific candidate target primary node, one of the multiple candidate target secondary nodes may be selected, for example, the selected one of the candidate target secondary nodes may have the highest received signal at the dual-connected user device, or the selected one of the candidate target secondary nodes may be randomly selected, wherein synchronization to the selected candidate target secondary node may be performed. The dual-connected user device may be synchronized to the candidate target secondary node. Previously, the configuration was applied to the candidate target secondary nodes The dual-connection user equipment may use a synchronization process to synchronize to a specific candidate target primary node and a specific candidate target secondary node. For example, the synchronization process may be a random access process (RACH) of an LTE or 5G NR system. After synchronization, the dual-connection user equipment may communicate with the specific candidate target primary node and the candidate target secondary node. In dual connection. The dual connection user equipment can execute synchronization to a specific candidate target secondary node before or after synchronization to a specific candidate target primary node. of synchronization.

[0040] The specific candidate target primary node can be a candidate target secondary node that meets the CPC condition. Associated n j A subset of candidate target master nodes However, if a particular candidate target master node is not n j A subset of candidate target master nodes As part of the dual-connection user equipment, the dual-connection user equipment can further continue to monitor the CPC condition and the CHO condition.

[0041] The present subject matter can achieve a faster data forwarding process than the so-called delayed data forwarding. If the so-called early data forwarding is not mandatory, the present subject matter can achieve low interruption time and low data forwarding overhead. Therefore, the present subject matter can achieve uninterrupted availability and high reliability of communication between the device and the base station of the communication system. This can meet the ultra-reliable and low-delay communication (URLLC) requirements during the user equipment handover process.

[0042] According to an example, the apparatus may receive a signal indicating a candidate target secondary node from a dual-connection user equipment. The dual-connection user equipment may use the connection to the device to send the message to inform the device that the leaving condition is met by the candidate target secondary node. Upon receiving this message, the device may stop sending requests to the candidate secondary node. And to the candidate target auxiliary node A subset of candidate target nodes associated with This may be advantageous in the case where a dual-connected user equipment moves to a primary secondary cell served by another candidate target secondary node.

[0043] In one example, if the CHO condition has not been met, the dual-connection user equipment may send a signal indicating a candidate target secondary node. Messages that meet the leaving conditions. For example, in the CPC condition, the candidate target secondary node After the CPC condition is satisfied, the dual-connection user equipment may repeatedly evaluate the CPC leaving condition. The CPC leaving condition may, for example, be defined as the opposite of the CPC condition. For example, after the CPC condition is satisfied, the dual-connection user equipment may continue to check whether each candidate target secondary node in the candidate target secondary node satisfies the CPC condition, and if the CPC condition is no longer satisfied by the candidate target secondary node, the dual-connection user equipment may continue to check whether each candidate target secondary node in the candidate target secondary node satisfies the CPC condition. If the CPC condition is satisfied, the dual-connection user equipment may determine that the CPC leaving condition is satisfied. Alternatively, the CPC leaving condition may be defined independently of the CPC condition. For example, the reconfiguration information received by the dual-connection user equipment may also indicate the CPC leaving condition. In this case, the dual-connection user equipment may repeatedly check whether there is only a candidate target secondary node. CPC departure conditions are met.

[0044] If multiple candidate target secondary nodes satisfy the CPC condition, the CPC leave condition may be checked for the multiple candidate target secondary nodes. If the CPC leave condition is satisfied by multiple candidate target secondary nodes, the device may stop forwarding data to the multiple candidate target secondary nodes and all associated subsets of the candidate target nodes. If the CPC leave condition is satisfied by only a portion of the multiple candidate target secondary nodes, the device may stop forwarding data to the portion of the candidate target secondary nodes and the associated candidate target primary nodes, and continue forwarding data to another portion of the candidate target secondary nodes and the associated candidate target primary nodes.

[0045] In one example, the device may stop forwarding data to a candidate target master node in a subset of candidate target master nodes different from the specific candidate target master node via the device receiving a switching success message from the specific candidate target master node. In addition, if the path switching to the specific candidate target master node is completed, the device may stop forwarding data to the specific candidate target master node.

[0046] For example, a device APP is provided. The device APP includes: 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 enable the device to be used together with the at least one processor to: send a message for conditional switching (referred to herein as a reconfiguration message) to the user equipment UE1, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; in response to the sending of the reconfiguration message, receive a message indicating a specific candidate target secondary node in the candidate target secondary node from the user equipment; perform data forwarding to the specific candidate target secondary node, and to a subset of the candidate target primary nodes associated with the specific candidate target secondary node. In one example, during the dual connection operation of the user equipment UE1, the device APP can serve the user equipment UE1. The user equipment UE1 can be connected to the device APP. During the dual connection operation, the user equipment UE1 can also be connected to the secondary node.

[0047] Figure 1 An example of a simplified system architecture is depicted, showing only some elements and functional entities, which are all logical units, the implementation of which may differ from what is shown. Figure 1 The connections shown are logical connections; the actual physical connections may be different. It is clear to those skilled in the art that the system may generally include in addition to Figure 1 Other functions and structures than those shown.

[0048] However, the embodiments are not limited to the systems given as examples, but a person skilled in the art may apply the solution to other communication systems provided with the necessary properties.

[0049] Figure 1 The example of FIG. 1 shows a portion of an exemplary radio access network.

[0050] Figure 1 Devices 110 and 112 are shown. For example, devices 110 and 112 can be user equipment. Devices 110 and 112 are configured to be wirelessly connected to node 114 on one or more communication channels. Node 114 is also connected to core network 120. In one example, node 114 can be an access node (such as (e / g)NodeB) 114 that provides or serves devices in a cell. In one example, node 114 can be a non-3GPP access node. The physical link from the device to the (e / g)NodeB is called an uplink or reverse link, and the physical link from the (e / g)NodeB to the device is called a downlink or forward link. It should be understood that the (e / g)NodeB or its functions can be implemented by using any node, host, server or access point entity suitable for such a purpose.

[0051] The communication system usually includes more than one (e / g)NodeB, in which case the (e / g)NodeB may also be configured to communicate with each other via wired or wireless links designed for this purpose. These links may be used for signaling purposes. (e / g)NodeB is a computing device configured to control the radio resources of the communication system to which it is coupled. NodeB may also be referred to as a base station, an access point, or any other type of interface device, including a relay station capable of operating in a wireless environment. (e / g)NodeB includes or is coupled to a transceiver. From the transceiver of the (e / g)NodeB, a connection is provided to an antenna unit, which establishes a bidirectional radio link to the device. The antenna unit may include multiple antennas or antenna elements. (e / g)NodeB is further connected to a core network 20 (CN or next generation core NGC). For example, (e / g)NodeB may be connected to an access and mobility management function (AMF) and a user plane function (UPF) in the control plane and the user plane, respectively. Depending on the system, the counterpart on the CN side may be a serving gateway (S-GW, routing and forwarding user data packets), a packet data network gateway (P-GW, for providing a connection between the device (UE) and an external packet data network), or a mobility management entity (MME), etc.

[0052] The device (also referred to as user equipment UE, user equipment, user terminal, terminal device, etc.) illustrates a type of device to which resources on the air interface are allocated and assigned, and therefore any features of the device described herein can be implemented with a corresponding device (such as a relay node). An example of such a relay node is a layer 3 relay (self-backhaul relay) towards a base station.

[0053] The device generally refers to a device (e.g., portable or non-portable computing device) including a wireless mobile communication device that utilizes or disadvantageously utilizes a subscriber identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smart phones, personal digital assistants (PDAs), handsets, devices using wireless modems (alarm or measurement devices, etc.), portable computers and / or touch screen computers, tablet computers, game consoles, laptops, and multimedia devices. It should be understood that the device can also be an almost exclusive uplink-only device, an example of which is a camera or video camera that loads images or video clips to a network. The device can also be a device with the ability to operate in an Internet of Things (IoT) network, in which an object can have the ability to send data over a network without human-to-human or human-to-computer interaction, such as for smart grids and connected vehicles. The device can also use the cloud. In some applications, the device can include a user-portable device (such as a watch, headset, or glasses) with a radio component, and the calculation is performed in the cloud. The user device (or in some embodiments, a layer 3 relay node) is configured to perform one or more of the user device functions. The apparatus may also be called a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, or user equipment (UE), to name just a few names or devices.

[0054] The various techniques described herein can also be applied to cyber-physical systems (CPS) (systems of cooperating computing elements that control physical entities). CPS can implement and utilize a large number of interconnected ICT devices (sensors, actuators, processor microcontrollers, etc.) embedded in different locations in physical objects. Mobile cyber-physical systems, in which the physical systems in question have inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0055] Furthermore, although the apparatus is depicted as a single entity, different units, processors and / or memory units may be implemented. Figure 1 Not all are shown).

[0056] 5G is able to use Multiple-Input Multiple-Output (MIMO) antennas, many more base stations or nodes than existing LTE systems (the so-called small cell concept), including macro sites cooperating with smaller base stations and employing multiple radio technologies, depending on service requirements, use cases and / or available spectrum. 5G mobile communications support a variety of use cases and related applications (including video streaming, augmented reality, different ways of sharing data and various forms of machine type applications, such as (massive) machine type communications (mMTC), including vehicle safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely, sub-6GHz, cmWave and mmWave, and also be integrable with existing conventional radio access technologies such as LTE. The integration with LTE can be implemented, at least in the early stages, as a system in which macro coverage is provided by LTE and 5G radio interface access comes from small cells by aggregation to LTE. In other words, 5G plans to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as sub-6GHz cmWave, sub-6GHz cmWave, mmWave). One of the concepts considered for use in 5G networks is network slicing, in which multiple independent and dedicated virtual subnets (network instances) can be created in the same infrastructure to run services with different requirements for latency, reliability, throughput and mobility.

[0057] The current architecture in LTE networks is completely distributed in the radio and completely centralized in the core network. Low-latency applications and services in 5G require content to be close to the radio, which leads to local bursts and multi-access edge computing (MEC). 5G enables analysis and knowledge generation to be performed at the data source. This approach requires the use of resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content near cellular subscribers to speed up response times. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer self-organizing networks and processing (also classified as local cloud / fog computing and grid / mesh computing), dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analysis, time-critical control, healthcare applications).

[0058] The communication system may also be capable of communicating with other networks, such as a public switched telephone network or the Internet, as shown by the component 122, or utilizing services provided by them. The communication network may also be capable of supporting the use of cloud services, for example, at least a portion of the core network operations may be provided as a cloud service (this is in the Figure 1 The communication system may also include a central control entity that provides facilities for networks of different operators to cooperate, for example, in spectrum sharing.

[0059] Edge cloud technology can be introduced into the radio access network (RAN) by leveraging network function virtualization (NVF) and software defined networking (SDN). Using edge cloud technology can mean that access node operations will be performed at least partially in a server, host or node that is operatively coupled to a remote radio head or base station including the radio part. Node operations can also be distributed among multiple servers, nodes or hosts. The application of cloudRAN architecture enables RAN real-time functions to be performed on the RAN side (in the distributed unit DU 114) and non-real-time functions to be performed in a centralized manner (in the centralized unit CU 118).

[0060] It should also be understood that the workload distribution between core network operations and base station operations may be different from LTE, or even non-existent. Some other technological advancements that may be used are big data and all-IP, which may change the way networks are built and managed. 5G is designed to support multiple hierarchical structures, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be understood that MEC can also be applied to 4G networks.

[0061] 5G can also make use of satellite communications to enhance or supplement the coverage of 5G services, for example by providing backhaul. Possible use cases are to provide service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers on board, or to ensure service availability for critical communications and future rail / maritime / aeronautical communications. Satellite communications can make use of geostationary orbit (GEO) satellite systems as well as low Earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano) satellites are deployed). Each satellite 116 in a mega-constellation can cover several satellite-enabled network entities creating a ground cell. The ground cell can be created via a ground relay node 114 or by a gNB located on the ground or in a satellite.

[0062] It will be appreciated by those skilled in the art that the depicted system is only an example of a portion of a radio access system, and in practice, the system may include multiple (e / g)NodeBs, which may access multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements. One of the (e / g)NodeBs may be a home (e / g)NodeB. In addition, in a geographical area of ​​a radio communication system, multiple different types of radio cells and multiple radio cells may be provided. A radio cell may be a macro cell (or umbrella cell), which is a large cell with a diameter typically up to tens of kilometers, or a smaller cell such as a micro, femto or pico cell. Figure 1 The (e / g)NodeB can provide any kind of these cells. A cellular radio system can be implemented as a multi-layer network including several kinds of cells. Typically, in a multi-layer network, one access node provides one or more cells of one kind, and thus multiple (e / g)NodeBs are required to provide such a network structure.

[0063] In order to meet the needs of improving the deployment and performance of communication systems, the concept of "plug and play" (e / g) NodeB is introduced. Usually, in addition to the home (e / g) NodeB (H(e / g) NodeB), the network that can use "plug and play" (e / g) NodeB also includes the home nodeB gateway or HNB-GW ( Figure 1 The HNB gateway (HNB-GW) usually installed in the operator's network can aggregate services from a large number of HNBs back to the core network.

[0064] Figure 2 is a schematic diagram of a wireless communication system 200. The communication system 200 may be configured to use a time division duplex (TDD) technique for data transmission.

[0065] For simplicity, the communication system 200 is shown to include four master nodes MN1, MN2, MN3 and MN4, three secondary nodes SN1, SN2 and SN3, and a user equipment 201. Each of the master nodes MN1 to MN4 and the secondary nodes SN1 to SN3 may be, for example, an eNodeB or a gNB, as shown in FIG. Figure 1 That is, the communication system 200 may support the same RAT or different RATs.

[0066] Each of the master nodes MN1 to MN4 may serve UEs within a respective geographic coverage area of ​​a service or cell 203.1 to 203.4. Each of the secondary nodes SN1 to SN3 may serve UEs within a respective geographic coverage area of ​​a service or cell 205.1 to 205.3.

[0067] In this particular example, the master node MN1 is associated with the secondary nodes SN1 and SN2. That is, the master node MN1 may be configured to be dual-connected with the secondary node SN1 and a user device such as UE 201. Alternatively, the master node MN1 may be configured to be dual-connected with the secondary node SN2 and a user device such as UE 201. The master node MN2 is associated with the secondary nodes SN1, SN2, and SN3. The master node MN3 is associated with the secondary nodes SN2 and SN3. The master node MN4 is associated with the secondary node SN3.

[0068] In this particular example, UE 201 is moving, for example, from left to right. Initially, UE 201 is in dual connectivity with master node MN1 and secondary node SN1. Therefore, master node MN1 may be referred to as source master node MN1, and secondary node SN1 may be referred to as source secondary node SN1.

[0069] When the user equipment 201 moves from left to right, it is configured to perform neighbor cell measurements on cells 203.2 to 203.3 and 205.2 to 205.3.

[0070] Figure 3 is a flow chart of a method according to an example of the present subject matter. For the purpose of explanation, Figure 3 The method described in Figure 2 The method is implemented in the system shown, but is not limited to this implementation. For example, the method can be executed by the source master node MN1.

[0071] The method starts at step 301, where the source master node MN1 may send a reconfiguration message for conditional handover to the user equipment 201. The reconfiguration message indicates a set of one or more candidate target master nodes and associated candidate target secondary nodes. Figure 2 In an example, the reconfiguration message indicates a set of candidate target master nodes MN2, MN3 and MN4 and associated candidate target secondary nodes SN2 and SN3. For example, the source master node MN1 can select master nodes MN2, MN3 and MN4 as candidate target master nodes for the mobile user equipment 201, for example, because they are neighboring nodes of the source master node MN1. For example, the reconfiguration message may include a data structure including the following pairing entries of the candidate target master nodes and the associated candidate target secondary nodes: {MN2, SN2}, {MN2, SN3}, {MN3, SN2}, {MN3, SN3} and {MN4, SN3}. The reconfiguration message may also include a CPC configuration and a CHO configuration. The CPC configuration may indicate a CPC condition that may be checked by the UE 201 and a configuration to be applied to a target secondary node that satisfies the CPC condition. The CPC configuration may also indicate a CPC departure condition. The CHO configuration may indicate a CHO condition that may be checked by the UE 201 and a configuration to be applied to a target master node that satisfies the CHO condition.

[0072] In response to sending the reconfiguration message, the source master node MN1 may receive a message (referred to as a CPC message) indicating a candidate target secondary node among the candidate target secondary nodes SN2 and SN3 from the user equipment 201 in step 303. For example, assuming that the candidate target secondary node SN2 is indicated in the CPC message, this indicates that the target secondary node SN2 satisfies the CPC condition.

[0073] Upon receiving the CPC message, the method proceeds to step 305, where the source master node MN1 can perform data forwarding to the candidate target secondary node SN2 and to a subset of candidate target master nodes associated with the candidate target secondary node SN2. For example, the source master node MN1 can use the received data structure to select an entry including the candidate target secondary node SN2. This can result in the following selected entries: {MN2, SN2} and {MN3, SN2}. Therefore, the subset of candidate target master nodes can include the master nodes MN2 and MN3 indicated in the selected entry. The data forwarding performed by the device can involve data that can serve the user equipment 201.

[0074] Figure 4 is a flow chart of a method used in a user device according to an example of the present subject matter. For the purpose of explanation, Figure 4 The method described in Figure 2 The method is implemented in the system shown, but is not limited to this implementation. For example, the method can be executed by the user equipment 201.

[0075] The method starts at step 401, where the user equipment 201 may receive a reconfiguration message for conditional handover from a source master node MN1. The reconfiguration message indicates a set of one or more candidate target master nodes and associated candidate target secondary nodes. Figure 2 In the example of, the reconfiguration message indicates a set of candidate target primary nodes MN2, MN3 and MN4 and associated candidate target secondary nodes SN2 and SN3. For example, the reconfiguration message may include a data structure including the following pairing entries of candidate target primary nodes and associated candidate target secondary nodes: {MN2, SN2}, {MN2, SN3}, {MN3, SN2}, {MN3, SN3} and {MN4, SN3}. The reconfiguration message may also include a CPC configuration and a CHO configuration. The CPC configuration may indicate a CPC condition that may be checked by UE 201 and a configuration to be applied to a target secondary node that satisfies the CPC condition. The CPC configuration may also indicate a CPC leave condition. The CHO configuration may indicate a CHO condition that may be checked by UE 201 and a configuration to be applied to a target primary node that satisfies the CHO condition.

[0076] Upon receiving the reconfiguration message, the user equipment 201 may check the CHO condition and the CPC condition in step 403. The user equipment 201 may check whether the CPC condition is satisfied by any one of the candidate target secondary nodes SN2 and SN3, and check whether the CHO condition is satisfied by any one of the candidate target primary nodes MN2, MN3, and MN4. For example, checking whether the CPC condition is satisfied by a given target SN (e.g., SN2) may require indicating that a signal value of a signal received from SN2 exceeds another signal value indicating a signal received from SN1 by at least a first offset value. Similarly, checking whether the CHO condition is satisfied by a given target MN (e.g., MN2) may require indicating that a signal value of a signal received from MN2 exceeds another signal value indicating a signal received from MN1 by at least a second offset value.

[0077] In the case where, for example, the CPC condition is satisfied by the candidate target secondary node SN2 (query step 404), before the CHO condition is satisfied, the method proceeds to step 405, where the user equipment 201 sends a message (CPC message) to the source master node MN1, which notifies the source master node MN1 that the candidate target secondary node SN2 satisfies the CPC condition. If the CPC condition is not satisfied before the CHO condition is satisfied, the user equipment 201 may continue to check the CPC condition until the CPC condition is satisfied.

[0078] Figure 5 is a flow chart of a method according to an example of the present subject matter. For the purpose of explanation, Figure 5 The method described in Figure 2 The method is implemented in the system shown, but is not limited to this implementation. For example, the method can be executed by the source master node MN1.

[0079] The method starts at step 501, where the source master node MN1 may send a reconfiguration message for conditional handover to the user equipment 201. The reconfiguration message indicates a set of one or more candidate target master nodes and associated candidate target secondary nodes. Figure 2In an example, the reconfiguration message indicates a set of candidate target master nodes MN2, MN3 and MN4 and associated candidate target secondary nodes SN2 and SN3. For example, the source master node MN1 can select master nodes MN2, MN3 and MN4 as candidate target master nodes for the mobile user equipment 201, for example, because they are neighboring nodes of the source master node MN1. For example, the reconfiguration message may include a data structure including the following pairing entries of the candidate target master nodes and the associated candidate target secondary nodes: {MN2, SN2}, {MN2, SN3}, {MN3, SN2}, {MN3, SN3} and {MN4, SN3}. The reconfiguration message may also include a CPC configuration and a CHO configuration. The CPC configuration may indicate a CPC condition that may be checked by the UE 201 and a configuration to be applied to a target secondary node that satisfies the CPC condition. The CPC configuration may also indicate a CPC departure condition. The CHO configuration may indicate a CHO condition that may be checked by the UE 201 and a configuration to be applied to a target master node that satisfies the CHO condition.

[0080] In response to sending the reconfiguration message, the source master node MN1 may receive a message (referred to as a CPC message) indicating a candidate target secondary node among the candidate target secondary nodes SN2 and SN3 from the user equipment 201 in step 503. For example, assuming that the candidate target secondary node SN2 is indicated in the CPC message, this indicates that the target secondary node SN2 satisfies the CPC condition.

[0081] Upon receiving the CPC message, the method proceeds to step 505, where the source master node MN1 can perform data forwarding to the candidate target secondary node SN2 and to a subset of candidate target master nodes associated with the candidate target secondary node SN2. For example, the source master node MN1 can use the received data structure to select an entry including the candidate target secondary node SN2. This can result in the following selected entries: {MN2, SN2} and {MN3, SN2}. Therefore, the subset of candidate target master nodes can include the master nodes MN2 and MN3 indicated in the selected entry. The data forwarding performed by the device can involve data that can serve the user equipment 201.

[0082] In step 507, the source master node MN1 may receive a message from the user equipment 201 indicating that the candidate target secondary node SN2 (which previously satisfied the CPC condition) has satisfied the CPC leave condition.

[0083] Upon receiving the message, the source master node MN1 may stop forwarding data to the candidate target secondary node SN2 and to a subset of the candidate target master nodes MN2 and MN3 associated with the candidate target secondary node SN2 in step 509 .

[0084] Figure 6is a flow chart of a method used in a user device according to an example of the present subject matter. For the purpose of explanation, Figure 6 The method described in Figure 2 The method is implemented in the system shown, but is not limited to this implementation. For example, the method can be executed by the user equipment 201.

[0085] The method starts at step 601, where the user equipment 201 may receive a reconfiguration message for conditional handover from a source master node MN1. The reconfiguration message indicates a set of one or more candidate target master nodes and associated candidate target secondary nodes. Figure 2 In the example of, the reconfiguration message indicates a set of candidate target primary nodes MN2, MN3 and MN4 and associated candidate target secondary nodes SN2 and SN3. For example, the reconfiguration message may include a data structure including the following pairing entries of candidate target primary nodes and associated candidate target secondary nodes: {MN2, SN2}, {MN2, SN3}, {MN3, SN2}, {MN3, SN3} and {MN4, SN3}. The reconfiguration message may also include a CPC configuration and a CHO configuration. The CPC configuration may indicate a CPC condition that may be checked by UE 201 and a configuration to be applied to a target secondary node that satisfies the CPC condition. The CPC configuration may also indicate a CPC leave condition. The CHO configuration may indicate a CHO condition that may be checked by UE 201 and a configuration to be applied to a target primary node that satisfies the CHO condition.

[0086] Upon receiving the reconfiguration message, the user equipment 201 may check the CHO condition and the CPC condition in step 603. The user equipment 201 may check whether the CPC condition is satisfied by any one of the candidate target secondary nodes SN2 and SN3, and check whether the CHO condition is satisfied by any one of the candidate target primary nodes MN2, MN3, and MN4. For example, checking whether the CPC condition is satisfied by a given target SN (e.g., SN2) may require indicating that a signal value of a signal received from SN2 exceeds another signal value indicating a signal received from SN1 by at least a first offset value. Similarly, checking whether the CHO condition is satisfied by a given target MN (e.g., MN2) may require indicating that a signal value of a signal received from MN2 exceeds another signal value indicating a signal received from MN1 by at least a second offset value.

[0087] If the CPC condition is satisfied by, for example, the candidate target secondary node SN2 before the CHO condition is satisfied (query step 604), the method proceeds to step 605, where the user equipment 201 sends a message (CPC message) to the source master node MN1, which notifies the source master node of the candidate target secondary node SN2 that satisfies the CPC condition. If the CPC condition is not satisfied before the CHO condition is satisfied, the user equipment 201 may continue to check the CPC condition until the CPC condition is satisfied.

[0088] After the CPC condition is met, the user equipment 201 may continue to monitor the CPC condition and the CHO condition. Monitoring the CPC condition may include checking whether the candidate target secondary node SN2 satisfies the CPC leaving condition, for example, if the CPC condition is no longer satisfied by SN2, this indicates that SN2 satisfies the CPC leaving condition. In the case where the leaving condition is satisfied by the candidate target secondary node SN2 (query step 607), the user equipment 201 may send a message to the source master node MN1 in step 609, indicating that the candidate target secondary node SN2 (which previously satisfied the CPC condition) has satisfied the CPC leaving condition. If the CPC leaving condition is not satisfied, the user equipment 201 may continue to check the CPC leaving condition until the CPC leaving condition is satisfied.

[0089] Figure 7 An example of a signaling diagram between a user equipment 701, a source primary node 702, a source secondary node 703, one or more candidate target secondary nodes 704, one or more candidate target primary nodes 705, a first core network node 707 (e.g., a user plane function (UPF)), and a second core network node 708 (e.g., an access and mobility management function (AMF)) according to an example of the present subject matter is depicted. Figure 7In the example of FIG. 7 , the user equipment 701 is first configured with a dual connection with the source master node 702 and the source secondary node 703. At 1, the source master node 702 may send a handover request to each of the candidate target master nodes 705. At 2, each of the candidate target master nodes 705 may send an SN add request to the corresponding candidate target secondary node 704. At 3, each of the candidate target secondary nodes 704 may reply to the corresponding candidate target master node 705 with an SN add request confirmation. At 4, each of the candidate target MNs 705 may send an Xn-U address indication message to the corresponding candidate target SN 704, the message including the address information of the interface Xn-U between the candidate target MN 704 and the corresponding candidate target SN 704. Specifically, the Xn-U address indication message may include the address information of the downlink (DL) transport network layer (TNL). At 5, each of the candidate target MNs 705 may send a handover request confirmation message to the source MN 702. The request confirmation message may include the TEID of each direct tunnel (e.g., DRB tunnel), which may be established by the source MN 702 and the corresponding candidate target MN 705 or candidate target SN 704 to perform data forwarding. At 6, the source MN 702 may send an XN-U address indication message to the source SN 703 to transmit data forwarding information. At 7, the source MN 702 may trigger the UE 701 to perform handover and cell change, and apply the configuration. Specifically, the source MN 702 may send an RRC connection reconfiguration message to achieve on-time data forwarding. At the same time, the source MN 702 may provide a flag to the UE 701 at 7 so as to configure the UE 701 to send a notification message when the CPC condition is met. The source MN 702 may also configure the UE 701 to include PCell measurement and CHO condition status (whether the TTT for the CHO condition is running, etc.) in the CPC message. At 8, the UE 701 may monitor the CHO condition and the CPC condition. The CPC condition may also be referred to as the CPAC condition. UE 701 may check whether candidate target MN 705 satisfies the CHO condition and whether candidate target SN 704 satisfies the CPC condition. At 9, the CPC condition may be satisfied by the candidate target SN (referred to as target SN-1), while the CHO condition is not satisfied. Target SN-1 may serve the primary and secondary cell PSCell-1. Target SN-1 may be associated only with a subset of candidate target MN 705. At 10, UE 701 may send a message (CPC message) to source MN 702 indicating that the CPC condition is satisfied by target SN-1. Optionally, the CPC message may also include the status of the current CHO measurement and CHO condition. At 11, UE 701 continues to check the CHO condition and CPC condition.The CHO condition may be checked for each candidate target MN in the candidate target MN 705. The CPC condition may be checked for each candidate target SN in the candidate target SN 704. At 12, the source MN 702 may select a subset of candidate target MNs associated with the target SN-1. For example, at 12, the source MN 702 may select a TEID for the DRB of the target PSCell-1 and the DRB of the corresponding subset of the PCell. By selecting a portion of the PCell subset based on the CHO PCell measurement, the PCell subset may be further reduced. The source MN 702 may use the selected TEID to establish a direct tunnel with the subset of candidate target MNs and with the target SN-1. The source MN 702 may send a sequence number status to the subset of candidate target MNs 705 at 14, including the sequence number status received from the source SN 703 at 13. Each candidate target MN in the subset of candidate target MNs 705 may forward the sequence number status to the associated candidate target SN 704 at 15. Data forwarding occurs at 16 and 17. Source MN 702 may perform data forwarding to a subset of candidate target MNs 705 and the associated candidate target SN-1. At 18, the CHO condition is satisfied by one candidate target node in the subset of candidate target MNs 705 (referred to as target MN-1).

[0090] The UE may perform a RACH procedure at 19 to synchronize with the target MN-1, and then perform an RRC completion procedure between the UE 701 and the target MN-1 705 at 20. At 21, the target MN-1 705 may send a handover success message to the source MN 702. At 22, the source MN 702 may send an SN release request to the source SN 703. At 23, the source SN 703 may send an SN release request confirmation to the source MN 702. At 24, the source SN 703 may perform a sequence number status transfer to the source MN 702. At 25, the source MN 702 may perform a sequence number status transfer to the target MN-1 705. At 26, the target MN-1 705 may perform a sequence number status transfer to the target SN-1 704. At 27, the UE 701 may perform a RACH procedure to synchronize to the target SN-1 704. At 28, the target MN-1 705 may send an SN reconfiguration complete message to the target SN-1 704. At 29, the source SN 703 may send a secondary RAT usage report to the source MN 702. At 30, the source MN 702 may send a secondary RAT usage report to the AMF 708. At 31, the target MN-1 705 may send a path switch request to the AMF 708. At 32, the AMF 708 may send a bearer modification request to the UPF 707. At 33, the UPF 707 may send a new path to the target MN-1 705. At 34, the UPF 707 may send a new path to the target SN-1 704. At 35, the AMF 708 may send a path switch request confirmation to the target MN-1 705. At 36, the target MN-1 may initiate a UE context release procedure to the source MN 702. Upon receiving the UE context release message from the source MN 702 at 37 , the source SN 703 may release the C-plane related resources associated with the UE context to the source MN 702 .

[0091] Figure 8 An example of a signaling diagram between a user equipment 801, a source primary node 802, a source secondary node 803, one or more candidate target secondary nodes 804, one or more candidate target primary nodes 805, a first core network node 807 (e.g., a user plane function (UPF)), and a second core network node 808 (e.g., an access and mobility management (AMF)) according to an example of the present subject matter is depicted. Figure 8In the example of FIG. 8 , the user equipment 801 is first configured with a dual connection with the source master node 802 and the secondary node 803. At 1, the source master node 802 may send a handover request to each of the candidate target master nodes 805. At 2, each of the candidate target master nodes 805 may send an SN add request to the corresponding candidate target secondary node 804. At 3, each of the candidate target secondary nodes 804 may reply to the corresponding candidate target master node 805 with an SN add request confirmation. At 4, each of the candidate target MNs 805 may send an Xn-U address indication message to the corresponding candidate target SN 804, the message including the address information of the interface Xn-U between the candidate target MN 805 and the corresponding candidate target SN 804. Specifically, the Xn-U address indication message may include the address information of the downlink (DL) transport network layer (TNL). At 5, each of the candidate target MNs 805 may send a handover request confirmation message to the source MN 802. The request confirmation message may include the TEID of each direct tunnel (e.g., DRB tunnel), which may be established by the source MN 802 and the corresponding candidate target MN 805 or candidate target SN 804 to perform data forwarding. At 6, the source MN 802 may send an XN-U address indication message to the source SN 803 to transmit data forwarding information. At 7, the source MN 802 may trigger the UE 801 to perform handover and cell change, and apply the configuration. Specifically, the source MN 802 may send an RRC connection reconfiguration message to achieve on-time data forwarding. At the same time, the source MN 702 may provide a flag to the UE 701 at 7 so as to configure the UE 701 to send a notification message when the CPC condition is met. The source MN 702 may also configure the UE 701 to include PCell measurement and CHO condition status (whether the TTT for the CHO condition is running, etc.) in the CPC message. At 8, the UE 801 may monitor the CHO condition and the CPC condition. UE 801 can check whether candidate target MN 805 satisfies the CHO condition and whether candidate target SN 804 satisfies the CPC condition. At 9, the CPC condition can be satisfied by the candidate target SN (referred to as target SN-1), while the CHO condition is not satisfied. Target SN-1 can serve the primary and secondary cell PSCell-1. Target SN-1 can be associated only with a subset of candidate target MN 805. At 10, UE 801 can send a message to source MN 802 indicating that the CPC condition is satisfied by target SN-1. Optionally, the message can also include the status of the current CHO measurement and CHO condition. At 11, UE 801 continues to check the CHO condition and the CPC condition. The CHO condition can be checked for each candidate target MN in candidate target MN 805.The CPC condition may be checked for each candidate target SN in the candidate target SN 804. At 12, the source MN 802 may select a subset of candidate target MNs associated with the target SN-1. For example, at 12, the source MN 802 may select a TEID for the DRB of the target PSCell-1 and the DRB of the corresponding subset of the PCell. The PCell subset may be further reduced by selecting a portion of the PCell subset based on the CHO PCell measurement. The source MN 802 may use the selected TEID to establish a direct tunnel with the subset of candidate target MNs and with the target SN-1. The source MN 802 may send a sequence number status to the subset of candidate target MNs 805 at 14, including the sequence number status received from the source SN 803 at 13. Each candidate target MN in the subset of the candidate target MNs 805 may forward the sequence number status to the associated candidate target SN 804 at 15. Data forwarding occurs at 16 and 17. The source MN 802 may perform data forwarding to a subset of the candidate target MNs 805 and the associated candidate target SN-1.

[0092] At 18, the CPC leaving condition is satisfied. At 19, UE 801 uses the connection to source MN 802 to inform the source MN of the fact that the CPC leaving condition is satisfied for target SN-1 804 (or PSCell-1). At 20, source MN 802 may stop data forwarding to the corresponding target MN 805 and target SN-1. At 21, UE 801 may perform CHO and CPC condition monitoring. CPC leaving condition may also be referred to as CPAC leaving condition.

[0093] Fig.9A is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment in a communication system 900 according to an example of the present subject matter.

[0094] exist Fig.9A In the example of FIG. 1 , user equipment 901 is first configured with dual connections with a source primary node and a source secondary node (not shown). User equipment 901 is served by a source primary node in a primary cell 903.1. User equipment 901 is served by a source secondary node in a primary secondary cell 905.1. Communication system 900 also includes two primary and secondary cells 905.2 and 905.3 served by corresponding secondary nodes, and two primary cells 903.2 and 903.3 served by corresponding primary nodes.

[0095] In this particular example, user device 901 is moving along trajectory 907 . Fig.9AThree positions 910.1, 910.2 and 910.3 of the user equipment 901 along the trajectory 907 are shown. Initially, the user equipment 901 is at position 910.1, at which the user equipment 901 receives a reconfiguration message indicating the CHO and CPC configurations from the source master node. While moving, the user equipment 901 can check the CPC condition and the CHO condition. At position 910.2 of the user equipment 901, the CPC condition is satisfied by the primary and secondary cells 905.2. Therefore, the user equipment 901 can notify the source master node accordingly so that the source master node can start forwarding data to the secondary node serving cell 905.2 and to the two other master nodes, because they are all associated with the primary and secondary cells 905.2, that is, their corresponding serving cells 903.2 to 903.3 overlap with the primary and secondary cells 905.2. When data forwarding is ongoing and the user equipment 901 is at position 910.3, the CHO condition is satisfied by the primary cell 903.3 because the user equipment 901 is within the primary cell 903.3. Therefore, the user equipment 901 can synchronize to the primary node serving the primary cell 903.3 and to the secondary node serving the primary secondary cell 905.2.

[0096] Fig. 9B is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment in a communication system 900 according to an example of the present subject matter.

[0097] exist Fig. 9B In the example of FIG. 1 , user equipment 901 is first configured with dual connectivity with a source primary node and a secondary node (not shown). User equipment 901 is served by a source primary node in a primary cell 903.1. User equipment 901 is served by a source secondary node in a primary secondary cell 905.1. Communication system 900 also includes two primary secondary cells 905.2 and 905.3 served by corresponding secondary nodes, and two primary cells 903.2 and 903.3 served by corresponding primary nodes.

[0098] In this particular example, user device 901 is moving along trajectory 917 . Fig. 9BThree positions 920.1, 920.2 and 920.3 of the user equipment 901 along the trajectory 917 are shown. Initially, the user equipment 901 is at position 920.1, at which the user equipment 901 receives a reconfiguration message indicating the CHO and CPC configurations from the source master node. While moving, the user equipment 901 can check the CPC condition and the CHO condition. At the position 920.2 of the user equipment 901, the CPC condition is satisfied by the primary and secondary cells 905.2. Therefore, the user equipment 901 can notify the source master node accordingly so that the source master node can start forwarding data to the secondary node serving cell 905.2 and to the two other master nodes, because they are all associated with the primary and secondary cells 905.2, that is, their corresponding serving cells 903.2 to 903.3 overlap with the primary and secondary cells 905.2. However, when data forwarding is ongoing and the user equipment 901 is at position 920.3, the CPC leaving condition is satisfied by the primary secondary cell 905.2, because the user equipment 901 is now closer to the primary secondary cell 905.3, which in principle can satisfy the CPC condition when the UE 901 is at position 920. Therefore, the user equipment 901 can notify the source primary node accordingly so that the source primary node can stop data forwarding.

[0099] Fig. 9C is a diagram illustrating a process of monitoring CPC conditions and CHO conditions by a user equipment in a communication system 900 according to an example of the present subject matter.

[0100] exist Fig. 9C In the example of FIG. 1 , user equipment 901 is first configured with dual connectivity with a source primary node and a secondary node (not shown). User equipment 901 is served by a source primary node in a primary cell 903.1. User equipment 901 is served by a source secondary node in a primary secondary cell 905.1. Communication system 900 also includes two primary secondary cells 905.2 and 905.3 served by corresponding secondary nodes, and two primary cells 903.2 and 903.3 served by corresponding primary nodes.

[0101] In this particular example, user device 901 is moving along trajectory 927 . Fig. 9CThree positions 930.1, 930.2 and 930.3 of the user equipment 901 along the trajectory 907 are shown. Initially, the user equipment 901 is at position 930.1, at which the user equipment 901 receives a reconfiguration message indicating the CHO and CPC configurations from the source master node. While moving, the user equipment 901 can check the CPC condition and the CHO condition. At the position 930.2 of the user equipment 901, the CPC condition is satisfied by the primary and secondary cells 905.2. Therefore, the user equipment 901 can notify the source master node accordingly so that the source master node can start forwarding data to the secondary node serving cell 905.2 and to the two other master nodes, because they are all associated with the primary and secondary cells 905.2, that is, their corresponding serving cells 903.2-3 overlap with the primary and secondary cells 905.2. However, when data forwarding is ongoing and the user equipment 901 moves to position 930.3, the CPC leaving or exiting condition is satisfied by the primary secondary cell 905.2 because the user equipment 901 is now located in the primary cell 903.1. Therefore, the user equipment 901 can notify the source primary node accordingly so that the source primary node can stop data forwarding.

[0102] exist Fig.10 , a circuit block diagram of a configuration of an illustrated device 1070 is shown, which is configured to implement at least a portion of the present subject matter. It should be noted that Fig.10 The device 1070 shown may include several other elements or functions in addition to those described below, which are omitted here for simplicity because they are not necessary for understanding. In addition, the device may also be another device with similar functions, such as a chipset, a chip, a module, etc., which may also be a part of the device or attached to the device 1070, etc. as a separate element. The device 1070 may include a processing function or a processor 1071, such as a central processing unit (CPU), etc., which executes instructions given by a program related to a flow control mechanism, etc. The processor 1071 may include one or more processing parts dedicated to a specific process as described below, or the process may be run in a single processor. The part for performing such a specific process may also be provided as a discrete element, or provided in one or more other processors or processing parts, such as in a physical processor (such as a CPU) or in several physical entities. Reference numeral 1072 represents a transceiver or input / output (I / O) unit (interface) connected to the processor 1071. The I / O unit 1072 may be used to communicate with one or more other network elements, entities, terminals, etc. The I / O unit 1072 may be a combined unit including communication devices toward several network elements, or may include a distributed structure with a plurality of different interfaces for different network elements. Reference numeral 1073 denotes a memory that may be used, for example, to store data and programs to be executed by the processor 1071 and / or used as a working memory for the processor 1071.

[0103] The processor 1071 is configured to perform processing related to the above-mentioned subject matter. Specifically, the device 1070 may be configured to perform a combination of Figure 3 , Figure 4 , Figure 5 or Figure 6 The method described.

[0104] For example, processor 1071 is configured to: send a reconfiguration message for conditional switching to a user device, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes, the device receiving a message indicating a specific candidate target secondary node among the candidate target secondary nodes from the user device in response to the sending of the reconfiguration message, and the device performing data forwarding to the specific candidate target secondary node, and to a subset of candidate target primary nodes associated with the specific candidate target secondary node.

[0105] Alternatively, the processor 1071 is configured to: receive a reconfiguration message for conditional switching from the device, the reconfiguration message indicating a condition for conditional switching to a set of candidate target primary nodes (referred to herein as a CHO condition), and another condition for conditional primary-secondary cell change (CPC) to a candidate target secondary node (referred to herein as a CPC condition); evaluate the CHO condition and the CPC condition; and in response to determining that the CPC condition is satisfied by a specific candidate target secondary node among the candidate target secondary nodes, send a message indicating the specific candidate target secondary node to the device.

[0106] Those skilled in the art will appreciate that aspects of the present invention may be embodied as devices, methods, computer programs or computer program products. Therefore, aspects of the present invention may take the form of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, which are generally referred to herein as "circuits", "modules" or "systems". In addition, aspects of the present invention may take the form of a computer program product embodied in one or more computer-readable media, which includes computer executable code. A computer program includes computer executable code or "program instructions".

[0107] Any combination of one or more computer readable media may be utilized. A computer readable medium may be a computer readable storage medium. As used herein, "computer readable storage medium" includes any tangible storage medium that can store instructions that can be executed by a processor of a computing device. A computer readable storage medium may be referred to as a computer readable non-transitory storage medium. A computer readable storage medium may also be referred to as a tangible computer readable medium. In some embodiments, a computer readable storage medium may also be capable of storing data that can be accessed by a processor of a computing device.

[0108] "Computer memory" or "memory" is an example of a computer-readable storage medium. Computer memory is any memory that is directly accessible to a processor. "Computer storage" or "storage" is another example of a computer-readable storage medium. Computer storage is any non-volatile computer-readable storage medium. In some embodiments, computer storage may also be computer memory and vice versa.

[0109] As used herein, 'processor' includes an electronic component capable of executing a program or machine executable instructions or computer executable code. References to computing devices that include a "processor" should be interpreted as possibly containing more than one processor or processing core. A processor may, for example, be a multi-core processor. A processor may also refer to a collection of processors within a single computer system or distributed between multiple computer systems. The term computing device should also be interpreted as possibly referring to a collection or network of computing devices, each of which includes one or more processors. Computer executable code may be executed by multiple processors, which may be within the same computing device, or may even be distributed across multiple computing devices.

[0110] Computer executable code may include machine executable instructions or programs that cause a processor to perform an aspect of the present invention. Computer executable code for performing the operations of aspects of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​(such as Java, Smalltalk, C++, etc.) and traditional procedural programming languages ​​(such as "C" programming language or similar programming languages), and compiled into machine executable instructions. In some cases, the computer executable code may be in the form of a high-level language or in a precompiled form and used in conjunction with an interpreter that generates machine executable instructions on the fly.

[0111] Typically, program instructions can be executed on one processor or several processors. In the case of multiple processors, the processors may be distributed across several different entities. Each processor may execute a portion of the instructions for that entity. Thus, when referring to a system or process involving multiple entities, a computer program or program instructions is understood to be suitable for execution by a processor associated or associated with the respective entity.

Claims

1. An apparatus configured as a master node to serve a user equipment in dual connectivity, the apparatus comprising components configured to: sending a message for conditional switching, referred to herein as a reconfiguration message, to the user equipment, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; In response to the sending of the reconfiguration message, receiving from the user equipment a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes; Data forwarding is performed to the at least one specific candidate target secondary node and to a subset of the candidate target primary nodes associated with the at least one specific candidate target secondary node.

2. The apparatus according to claim 1, wherein the component is configured to: receiving a measurement report from the user equipment; In response to receiving the measurement report, evaluating the measurement reports and sending a handover request to the set of candidate target master nodes based on the evaluation; receiving, from the set of candidate target primary nodes, a handover request confirmation indicating the candidate target secondary node; In response to receiving the handover request confirmation, submitting the reconfiguration message is performed.

3. The device according to any one of the preceding claims, wherein the component is configured to: While performing the data forwarding, receiving a message from the user equipment indicating that the at least one specific candidate target secondary node satisfies a leaving condition; and in response to receiving the message, The data forwarding to the at least one specific candidate target secondary node and to the subset of candidate target primary nodes is stopped.

4. The apparatus according to any one of the preceding claims, the reconfiguration message indicating: a condition for conditional switching to the set of candidate target primary nodes, and another condition for conditional primary-secondary cell change (CPC) to the candidate target secondary nodes.

5. The apparatus according to any one of the preceding claims, wherein the received message further indicates that the at least one specific candidate target secondary node satisfies a CPC condition defined in the reconfiguration message.

6. The apparatus according to any one of the preceding claims, wherein the received message comprises: Cell measurements performed by the user equipment on cells served by the set of the one or more candidate target primary nodes, wherein the component is further configured to select the subset of the candidate target primary nodes based on the cell measurements.

7. An apparatus according to any one of the preceding claims 2 to 6, wherein the switching request confirmation includes data indicating an endpoint of a direct tunnel; and the component is configured to: use the data to establish a direct tunnel between the apparatus and the at least one specific candidate target secondary node and the subset of the candidate target primary nodes for performing the data forwarding using the endpoint.

8. The apparatus of claim 7, the data comprising a tunnel endpoint identifier (TEID) of the direct tunnel.

9. According to the device described in any one of the preceding claims 2 to 8, the component is also configured to: receive a switching success from a specific candidate target master node in the set of candidate target master nodes, and in response to the reception of the switching success, stop forwarding the data to the candidate target node that is not the specific candidate target master node.

10. An apparatus according to any one of the preceding claims, wherein the component comprises at least one processor; and at least one memory comprising 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 execution of the apparatus.

11. A user equipment in dual connectivity with an apparatus acting as a source primary node and a source secondary node, the user equipment comprising components configured to: receiving a reconfiguration message for conditional handover from the apparatus, the reconfiguration message indicating: a condition for conditional handover CHO to a set of candidate target primary nodes, referred to herein as CHO condition, and another condition for conditional primary-secondary cell change (CPC) to a set of candidate target secondary nodes, referred to herein as CPC condition; evaluating the CHO conditions and the CPC conditions; In response to determining that the CPC condition is satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, a message indicating the at least one specific candidate target secondary node is sent to the device.

12. The user equipment of claim 11, the component being configured to send the message if the CHO condition is not met.

13. The user equipment according to any one of the preceding claims 11 to 12, wherein the component is configured to: In response to determining that the CHO condition is satisfied for a specific candidate target primary node, synchronizing the user equipment to the specific candidate target primary node, and synchronizing the user equipment to a selected specific candidate target secondary node among the at least one specific candidate target secondary node.

14. The user equipment according to any one of claims 11 to 13, wherein the message sent comprises: Cell measurements performed by the user equipment on cells served by the set of one or more candidate target master nodes.

15. The user equipment according to any one of the preceding claims 11 to 14, wherein the component is configured to: determining whether the at least one specific candidate target secondary node satisfies a CPC leaving condition; In case the CPC-leave condition is satisfied by the at least one specific candidate target secondary node, another message is sent to the apparatus indicating that the CPC-leave condition is satisfied by the at least one specific candidate target secondary node.

16. A user device according to any one of the preceding claims 11 to 15, wherein the component comprises at least one processor; and at least one memory comprising 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 execution of the user device.

17. A method comprising: sending, by the apparatus, a message for conditional handover to a user equipment, referred to herein as a reconfiguration message, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; In response to the sending of the reconfiguration message, receiving, by the apparatus from the user equipment, a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes; Data forwarding is performed by the apparatus to the at least one specific candidate target secondary node and to a subset of the candidate target primary nodes associated with the at least one specific candidate target secondary node.

18. The method according to claim 17, wherein the received message comprises: cell measurements performed by the user equipment on cells served by the set of the one or more candidate target primary nodes, the method further comprising: selecting the subset of the candidate target primary nodes based on the cell measurements.

19. A computer program comprising instructions for causing an apparatus to at least perform the following: sending a message for conditional switching, referred to herein as a reconfiguration message, to a user equipment, the reconfiguration message indicating a set of one or more candidate target primary nodes and associated candidate target secondary nodes; In response to the sending of the reconfiguration message, receiving from the user equipment a message indicating at least one specific candidate target secondary node among the candidate target secondary nodes; Data forwarding is performed to the at least one specific candidate target secondary node and to a subset of the candidate target primary nodes associated with the at least one specific candidate target secondary node.

20. A method comprising: receiving a reconfiguration message for conditional handover from a device, the reconfiguration message indicating: a condition for conditional handover to a set of candidate target primary nodes, referred to herein as a CHO condition, and another condition for conditional primary-secondary cell change (CPC) to a set of candidate target secondary nodes, referred to herein as a CPC condition; evaluating the CHO conditions and the CPC conditions; In response to determining that the CPC condition is satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, a message indicating the at least one specific candidate target secondary node is sent to the device.

21. A computer program comprising instructions for causing a user device to at least perform the following: receiving a reconfiguration message for conditional handover from a device, the reconfiguration message indicating: a condition for conditional handover to a set of candidate target primary nodes, referred to herein as a CHO condition, and another condition for conditional primary-secondary cell change (CPC) to a set of candidate target secondary nodes, referred to herein as a CPC condition; evaluating the CHO conditions and the CPC conditions; In response to determining that the CPC condition is satisfied by at least one specific candidate target secondary node among the candidate target secondary nodes, a message indicating the at least one specific candidate target secondary node is sent to the device.

Images