Slice group specific connected RACH configuration

Abstract

According to one aspect, an apparatus is provided for performing the following. The apparatus receives, from a first radio access network node, a network slice to network slice access layer group mapping of a second cell that is a target cell for handover. The second cell is provided by a second radio access network node. The apparatus determines a network slice access layer group for accessing the second cell based on a network slice-to-network slice access layer group mapping of the second cell. The apparatus selects a random access channel resource for accessing the second cell based on the network slice access layer group, and accesses the second cell using the random access channel resource.

Description

Technical Field

[0001] Various example embodiments relate to wireless communication. Background Art

[0002] Network slicing is a key feature of 5G for supporting different services using the same underlying mobile network infrastructure. Network slices can differ in their service requirements (such as ultra-reliable low-latency communication (URLLC) and enhanced mobile broadband (eMBB)) or the tenants providing these services. A network slice can be uniquely identified via its S-NSSAI (Single Network Slice Selection Assistance Information).

[0003] A given distributed unit (DU) of a distributed access node may have a set of network slice access stratum (AS) group-specific radio access channels (RACH) resources configured via operation, administration, and maintenance (OAM). The mapping between (multiple) network slices and (multiple) network slice AS groups may be tracking area (TA)-specific. Additionally, each neighboring cell with a different TA may be configured with a different network slice to network slice AS group mapping. In a handover scenario, the terminal device should be aware of and consider the network slice to network slice AS group mapping of the neighboring cell to ensure correct RACH resource usage in the terminal device and avoid violating the service level agreement (SLA). However, there is no such information available for the terminal to use. Summary of the Invention

[0004] According to one aspect, the subject matter of the independent claims is provided. Embodiments are defined in the dependent claims.

[0005] According to one aspect, a method is provided, including:

[0006] Determining that a handover of a terminal device from a first cell provided by a first access node to a second cell provided by a second access node is to be performed; and

[0007] Sending a network slice to network slice access stratum group mapping of the second cell to the first access node.

[0008] According to one aspect, a computer program product is provided, embodied on a non-transitory computer-readable medium, including program instructions that, when run, are adapted to perform:

[0009] Determining that a handover of a terminal device from a first cell provided by a first access node to a second cell provided by a second access node is to be performed; and

[0010] Sending a network slice to network slice access stratum group mapping of the second cell to the first access node.

[0011] One or more examples in the implementation are set forth in greater detail in the following drawings and description. Other features will be apparent from the description, the drawings, and the claims. Description of the Drawings

[0012] Hereinafter, example embodiments will be described in more detail with reference to the drawings, in which:

[0013] Figure 1 and Figure 2 shows an exemplary wireless communication system;

[0014] Figures 3 to 8 shows an exemplary process according to an embodiment; and

[0015] Figures 9 to 11 shows a device according to an embodiment. Detailed Description

[0016] The following embodiments are presented only as examples. Although this specification may refer to "one," "an," or "some" embodiments and / or examples at several places in the text, this does not necessarily mean that each reference is to the same (multiple) embodiment or (multiple) example, or that a particular feature applies only to a single embodiment and / or example. Individual features of different embodiments and / or examples may also be combined to provide other embodiments and / or examples.

[0017] Hereinafter, different exemplary embodiments will be described using Long Term Evolution Advanced (LTE-A, advanced LTE) or New Radio (NR, 5G) as an example of an access architecture to which these embodiments can be applied, but these embodiments are not limited to such an architecture. It will be apparent to those skilled in the art that by appropriately adjusting the parameters and processes, these embodiments can also be applied to other types of communication networks in a suitable manner. Some examples of other options for a suitable system are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE, substantially the same as E-UTRA), Wireless Local Area Network (WLAN or WiFi), Worldwide Interoperability for Microwave Access (WiMAX), Personal Communication Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, Mobile Ad Hoc Networks (MANET), and Internet Protocol Multimedia Subsystem (IMS), or any combination thereof.

[0018] Figure 1 An example of a simplified system architecture is described in which some of the elements and functional entities are logical units, and their implementation may be different from what is shown. Figure 1The connections shown are logical connections; the actual physical connections may be different. It will be apparent to those skilled in the art that the system generally also includes other functions and structures in addition to Figure 1 those shown.

[0019] However, the embodiments are not limited to the systems given as examples, but those skilled in the art may apply the solution to other communication systems provided with the necessary attributes.

[0020] Figure 1 The example of

[0021] Figure 1 shows a part of an exemplary radio access network.

[0022] User equipments 100 and 102 are shown, which are configured for wireless connection to an access point (e.g., (e / g)NodeB) 104 providing the cell on one or more radio channels in the cell. The physical connection from the user equipment to the (e / g)NodeB is referred to as the uplink or reverse link, and the physical connection from the (e / g)NodeB to the user equipment is referred to as the downlink or forward link. It should be understood that the (e / g)NodeB or their functions may be implemented by any entity such as a node, host, server, or access point suitable for such use.

[0023] A user equipment (also referred to as UE, user equipment, user terminal, terminal device, etc.) shows a device for allocating and designating air interface resources, so any feature of the user equipment described herein may be implemented by a corresponding device, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhaul relay) facing the base station.

[0024] A user equipment generally refers to a portable computing device, including a wireless mobile communication device operating with or without a subscriber identity module (SIM), including but not limited to the following types of devices: a mobile station (mobile phone), a smart phone, a personal digital assistant (PDA), a cellular phone, a device using a wireless modem (such as an alarm or measurement device), a laptop computer and / or a touch screen computer, a tablet computer, a game console, a notebook computer, and a multimedia device. It should be understood that the user equipment may also be an almost exclusive uplink device, an example of which is a camera or a video camera that loads images or video clips onto the network. The user equipment may also be a device capable of operating in an Internet of Things (IoT) network, which is a scenario where objects have the ability to transfer data over a network without human-to-human or human-to-computer interaction. The user equipment (or a layer 3 relay node in some embodiments) is configured to perform one or more user equipment functions. The user equipment may also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, or a user equipment (UE), to name just a few.

[0025] The various techniques described herein may also be applied to cyber-physical systems (CPSs) (a system of collaborative computing elements that control physical entities). CPSs may enable the implementation and development of a large number of interconnected ICT devices (sensors, actuators, processor microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber-physical systems are a subcategory of cyber-physical systems, where the physical systems under discussion have inherent mobility. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0026] It should be understood that in Figure 1 , for clarity only, the user equipment is depicted as including two antennas. The number of receiving and / or transmitting antennas may naturally vary according to the current implementation.

[0027] In addition, although these devices are described as a single entity, different units, processors, and / or storage units ( Figure 1 not all shown therein) may be implemented.

[0028] 5G can use multiple-input multiple-output (MIMO) antennas, have more base stations or nodes than LTE (the so-called small cell concept), including macro base stations operating in cooperation with small base stations, and adopt various radio technologies according to service requirements, use cases, and / or available spectrum. 5G mobile communication supports a wide range of use cases and related applications, including video streaming, augmented reality, different data sharing methods, and various forms of machine-type applications, including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple radio interfaces, namely below 6 GHz, centimeter wave, and millimeter wave, and is also capable of integrating with existing traditional radio access technologies (such as LTE). At least in the early stage, the integration with LTE can be implemented as a system where macro coverage is provided by LTE and the 5G radio interface accesses from small cells aggregated to LTE. In other words, 5G plans to support both inter-RAT interoperability (such as LTE-5G) and inter-RI interoperability (inter-radio interface interoperability, such as below 6 GHz - centimeter wave, below 6 GHz - centimeter wave - millimeter wave). One of the concepts considered to be used in 5G networks is network slicing, where multiple independent and dedicated virtual sub-networks (network instances) can be created within substantially the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0029] The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low-latency application and service requirements in 5G bring content closer to the radio, which leads to local breakout and multi-access edge computing (MEC). 5G enables analysis and knowledge generation to occur at the data source. This approach requires leveraging resources that may not be continuously connected to the network. MEC provides a distributed computing environment for application and service hosts. It can also store and process content closer to cellular subscribers to seek faster response times. Edge computing encompasses a wide range of technologies, such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer ad hoc networking and processing, and can also be classified as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlets, distributed data storage and retrieval, self-healing autonomous 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 analytics, time-critical control, healthcare applications).

[0030] The communication system can also communicate with other networks, such as the public switched telephone network or the Internet 112, or utilize the services provided by them. The communication network may also be able to support the use of cloud services. For example, at least part of the core network operations can be executed as cloud services (this is in Figure 1which is represented by the "cloud" 114). The communication system may also include a central control entity, etc., to provide equipment for different operators' networks to cooperate, such as in spectrum sharing.

[0031] The edge cloud can be introduced into the radio access network (RAN) by leveraging network function virtualization (NVF) and software-defined networking (SDN). Using the edge cloud may mean that access node operations are performed at least partially in servers, hosts, or nodes that are operationally coupled to a remote radio head or base station operation including wireless components. Node operations may also be distributed among multiple servers, nodes, or hosts. The application of the cloudRAN architecture enables RAN real-time functions to be executed on the RAN side (in the distributed unit DU 104), and non-real-time functions can be executed in a centralized manner (in the central or centralized unit CU 108).

[0032] It should also be understood that the division of labor between core network operations and base station operations may be different from that of LTE or even non-existent. Some other technological advancements that may be used are big data and all-IP, which may change the way the network is built and managed. 5G (or new radio, NR) networks are being designed to support multiple levels, 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 in 4G networks.

[0033] 5G can also utilize satellite communication to enhance or supplement the coverage of 5G services, such as by providing backhaul. Possible use cases are to provide service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or in-vehicle passengers, or to ensure service availability for critical communications and future railway / maritime / aviation communications. Satellite communication can utilize geostationary orbit (GEO) satellite systems or low Earth orbit (LEO) satellite systems, especially mega-constellations (systems in which hundreds (nanosatellites) are deployed). At least one satellite 106 in the mega-constellation can cover multiple satellite-enabled network entities that create a ground cell. The ground cell can be created by a ground relay node 104 or by a gNB located on the ground or in a satellite.

[0034] It is obvious to those skilled in the art that the depicted system is merely an example of a part of a radio access system, and in practice, the system may include multiple (e / g)NodeBs, user equipment can access multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements, etc. At least one of the (e / g)NodeBs can be a home (e / g)NodeB. In addition, in the geographical area of a radio communication system, multiple different types of radio cells and multiple radio cells can be provided. A radio cell can be a macro cell (or umbrella cell), which is a large cell usually having a diameter of up to dozens of kilometers, or a smaller cell, such as a micro, femto or pico cell. Figure 1 The (e / g)NodeB can provide any of these types of cells. A cellular radio system can be implemented as a multi-layer network including multiple types of cells. Usually in a multi-layer network, one access node provides one or several types of cells, so multiple (e / g)NodeBs are required to provide such a network structure.

[0035] To meet the requirements of improving the deployment and performance of a communication system, the concept of "plug-and-play" (e / g)NodeB is introduced. Generally, a network capable of using "plug-and-play" (e / g)NodeBs includes, in addition to a home (e / g)NodeB (H(e / g)nodeB), a home node B gateway or HNB-GW ( Figure 1 not shown in the figure). The HNB gateway (HNB-GW), which is usually installed within an operator's network, can aggregate traffic from a large number of HNBs back to the core network.

[0036] The 6G network is expected to utilize local spectrum licensing, spectrum sharing, infrastructure sharing, and intelligent automation management supported by mobile edge computing, artificial intelligence, short-packet communication, and blockchain technology to adopt flexible decentralized and / or distributed computing systems and architectures, as well as pervasive computing. The key features of 6G will include intelligent connection management and control functions, programmability, integrated sensing and communication, reduction of the energy footprint, reliable infrastructure, scalability, and affordability. In addition to this, 6G also aims at new use cases, covering integrating positioning and sensing functions into the system definition to unify the user experience across the physical and digital worlds.

[0037] Figure 2 Another example of a communication system 200 in which some examples can be applied is shown. Specifically, the shown communication system adopts a decomposed RAN architecture, where the RAN functions are distributed among different unique units that form the RAN. In other words, the RAN protocol stack is effectively split into multiple RAN protocol stacks, such that each component can be implemented independently. The communication system 200 can correspond to, as described with respect to Figure 1the communication system discussed herein or a part thereof. Thus, any one of the terminal devices 221, 222, 223 may correspond to Figure 1 one of the elements 100, 102 in Figure 1 . Further, the access node 104 in

[0038] may correspond to a combination of the elements 201, 202, 220 that form a distributed access node. The illustrated communication system may be based on a New Radio (NR) access technology. Figure 2 , the communication system 200 includes: two (remote) radio units or radio heads that provide respective (adjacent) cells 211, 222, a distributed unit 220 connected to at least one of the remote radio units 201, 202 via a wired and / or wireless communication link, and a central unit 230 connected to the distributed unit 220 via a wired or wireless communication link. The central unit 230 may also be connected to at least a Session Management Function (SMF) 240 via a wired or wireless communication link. This connection may be provided via one or more other functions or Figure 2 network entities not shown in

[0039] at least one of the elements 201, 202, 220, 230 may be associated with substantially the same access node (e.g., substantially the same gNB). At least one of the remote radio units 201, 202 may have MIMO capabilities (i.e., includes: a MIMO antenna array and components for performing beamforming using the MIMO antenna array). Further, the communication system 200 includes a plurality of terminal devices 221, 222, 223 located within the cells 211, 212. In other embodiments, the number of remote radio units may be different compared to the illustrated example, although to fully utilize the distributed architecture, the access node should include at least two remote radio units. While Figure 2 a single distributed unit 220 is shown for simplicity, in other embodiments, two or more distributed units 220 connected to substantially the same central unit 230 may be provided.

[0040] In some embodiments, the CU 230 may include separate units (or subunits, logical nodes, or entities): a control plane entity of the central unit (Central Unit-Control Plane, CU-CP), and a user plane entity of the central unit (Central Unit-User Plane, CU-UP). For example, the CU-CP may carry the radio resource control (RRC) and control plane parts of the packet data convergence protocol of the CU 230, while the CU-UP may carry the user plane part of the PDCP protocol and the SDAP protocol of the CU 230. The interface between the distributed unit 220 and the central unit 230 may be referred to as the F1 interface. Specifically, the interface between the DU 220 and the CP-CU may be referred to as the F1-C interface, and the interface between the DU 220 and the UP-CU may be referred to as the F1-U interface. The interface between the CU-CP and the CU-UP may be referred to as the E1 interface.

[0041] Although Figure 2 a decomposed RAN architecture is specifically shown, and some embodiments to be discussed below specifically relate to the decomposed RAN architecture, other embodiments may be specifically applied to a non-decomposed RAN architecture (i.e., a RAN architecture without CU-DU separation)

[0042] Figure 1 or Figure 2 any one of the communication systems in the communication system may support network slicing. Network slicing is a 5G feature for using the same underlying mobile network infrastructure to support different services. Network slices may differ in their service requirements (such as URLLC and eMBB) or the tenants providing these services.

[0043] A network slice (or just one slice for that matter) can be uniquely identified by its S-NSSAI (Single Network Slice Selection Assistance Information). A given terminal may be able to be connected and served by up to eight network slices corresponding to eight S-NSSAIs respectively. On the other hand, each cell provided by a distributed unit of an access point or a distributed access point may support dozens or even hundreds of network slices. In addition, a tracking area (TA) including a group (adjacent) of cells provided by one or more access points may support up to 1024 network slices.

[0044] The S-NSSAI may include or consist of a slice / service type (SST) field (8 bits in length) and a slice differentiator (SD) field (24 bits in length), with a total length of 32 bits. Alternatively, the S-NSSAI may consist only of the SST field, in which case the length of the S-NSSAI is only 8 bits.

[0045] The SST field can have a standardized or non-standardized value. Values from 0 to 127 belong to the standardized SST range. For example, an SST value of 1 may indicate that the slice is suitable for 5G eMBB processing, and a value of 2 may indicate processing for URLLC, etc. The SD field can be defined by the operator.

[0046] The NSSAI (defining one or more individual S-NSSAIs) may include one or more of the following types of information:

[0047] · Allowed NSSAI: The NSSAI provided by the serving public land mobile network (PLMN) during, for example, the registration process, indicating the S-NSSAI values that the terminal device can use in the serving PLMN for the current registration area (RA).

[0048] · Configured NSSAI: The NSSAI provided in the terminal device and applicable to one or more PLMNs.

[0049] · Pending NSSAI: The NSSAI provided by the serving PLMN during the registration process, indicating the (s) S-NSSAI for which the network slice-specific authentication and authorization process is pending.

[0050] S-NSSAI.

[0051] · Requested NSSAI: The NSSAI provided by the terminal device to the serving PLMN during registration.

[0052] · Rejected NSSAI: The NSSAI indicates that the network slice-specific authentication

[0053] and authorization (NSSAA) for the current PLMN or stand-alone non-public network (SNPN), for the current RA, for a failed or revoked one, and / or for an S-NSSAI for which the maximum number of terminal devices has been reached. · Subscribed S-NSSAI: The S-NSSAI based on subscriber information for which the terminal device is subscribed to use in the PLMN.

[0054] A given distributed unit (DU) of a distributed access node (or a given non - distributed access node) may have a set of network slice access stratum (AS) group (NSAG) - specific radio access channel (RACH) resources configured via operation, administration, and maintenance (OAM). The mapping of network slices to network slice AS groups may be tracking area (TA) - specific. Additionally, each neighboring cell with a different TA may be configured with a different mapping of network slices to network slice AS groups. In a handover scenario, the terminal device preferably knows and takes into account the mapping of network slices to network slice AS groups of the neighboring cell(s). However, the mapping of network slices to network slice AS groups is unknown to the target DU. This may lead to problems in the configuration of the terminal device and the use of RACH resources. During handover, the terminal device may not have the correct slice - group - specific RACH resources, which may result in service - level agreement (SLA) violations or incorrect use of RACH resources.

[0055] To further clarify the technical problem at hand, a simple non - restrictive example is provided below.

[0056] Let us assume that in a handover scenario, the source cell is associated with the following mapping of network slices to network slice AS groups: {SG1, URLLC, TA1}&{SG2, eMBB, TA1}, where SG1&SG2 are service groups 1&2 respectively, and TA1 is tracking area 1. Additionally, the target cell of the handover is associated with the following mapping of network slices to network slice AS groups: {SG2, URLLC, TA2}&{SG3, eMBB, TA2}, where SG3 is service group 3 and TA2 is tracking area 2. In other words, the terminal device in the source cell currently (i.e., before handover) has the mapping in TA1 and has the allowed network slices related to URLLC and eMBB, while the target DU has the mapping in TA2 and is not in random access (RA).

[0057] In a first exemplary handover scenario, the terminal device is assumed to initially have a protocol data unit (PDU) session on URLLC in the source cell. Then, the target DU allocates RACH resources for SG2 of the terminal device. On the other hand, the non - access stratum (NAS) of the terminal device indicates SG1 as the RACH resource(s) to be used for the terminal device. The terminal device determines that there are no RACH resources for the SG1 network slice AS group in the target cell. In this case, in some situations, the terminal device may still use SG2 or alternatively throw an error.

[0058] In a second exemplary handover scenario, the terminal device is assumed to initially have PDU sessions on URLLC and eMBB in a source cell. Then, the target DU allocates RACH resources for SG2 and SG3 of the terminal device. The terminal device non-access stratum (NAS) prioritizes eMBB and indicates SG2 as the (multiple) RACH resources to be used for the terminal device. The terminal device uses the SG2 RACH resources that it believes are for eMBB in the target cell, even though this configuration is actually for URLLC.

[0059] The embodiments to be discussed in detail below fully or at least partially overcome the above-mentioned deficiencies by enabling communication of the network slice to network slice AS group mapping of the terminal device during the handover process. Specifically, the embodiments can enable network slice / network slice AS group specific RACH configuration within the NG-RAN protocol on the intra-RAN and inter-RAN interfaces.

[0060] Figure 3 A flow as part of a handover process according to an embodiment is shown, which is for transferring the network slice to network slice AS group mapping of a terminal device in a serving or source cell to a target access node or a target distributed unit. The handover process discussed can be an inter-CU or intra-CU handover process for a distributed RAN architecture (or in some cases, an inter-access node handover process for a non-distributed RAN architecture, as described below in the assumed non-distributed RAN architecture after discussion Figure 3 ). The flow can be executed by a central unit of a distributed access node or specifically by a CU-CP entity of the central unit. Alternatively, the flow can be executed by a device for a central unit of a distributed access node or specifically for a CU-CP entity of the central unit. In other words, the device discussed can form part of the central unit or be (communicatively) connected to the central unit or specifically connected to its CU-CP entity. In the case of an inter-CU handover, the central unit can be specifically considered as the target central unit of the handover process. The central unit can correspond to Figure 1 the central unit 108 and / or Figure 2 the central unit 230. Hereinafter, for the sake of brevity, the participants in this process are simply referred to as devices.

[0061] Refer to Figure 3, in block 301, the device determines that an inter-CU handover or an intra-CU handover of the terminal device from a first cell provided by a first distributed unit to a second cell provided by a second distributed unit is to be performed. In block 301, determining that an inter-CU handover or an intra-CU handover is to be performed can be considered to mean that a network slice-specific RACH configuration (or specifically, beam failure recovery, BFR, network slice-specific RACH configuration) is required by the terminal device. The first distributed unit and the second distributed unit, as well as the first cell and the second cell, may also be referred to as the source distributed unit and the target distributed unit, and the source cell and the target cell, respectively.

[0062] If the handover in block 301 is an inter-CU handover, the first distributed unit and the second distributed unit are assumed to be connected to a first central unit and a second central unit (the second central unit includes a device that executes Figure 3 the process and is connected to the second distributed unit). Therefore, an inter-CU handover involves a handover between the first distributed unit and the second distributed access node. The first central unit and the second central unit, as well as the first distributed access node and the second distributed access node, may also be referred to as the source central unit and the target central unit, and the source distributed access node and the target distributed access node, respectively.

[0063] On the other hand, if the handover in block 301 is an intra-CU handover, the first distributed unit and the second distributed unit are assumed to be connected to the same central unit (i.e., the central unit that includes a device that executes Figure 3 the process in

[0064] ). Therefore, an intra-CU handover involves a handover between two distributed units of a single distributed access node. Figure 3 The determination in block 301 can be based on a measurement report received from the terminal device via the first distributed unit (assuming Figure 3 the process belongs to an intra-CU handover) or based on a handover request received from the terminal device via the first distributed unit and the first central unit (assuming

[0065] the process belongs to an inter-CU handover).

[0066] In the case of a handover within the CU, the transmission to the first distributed unit in block 302 can be performed directly (i.e., without going through any additional central unit), or in the case of a handover between CU units, it is performed via the first central unit of the first distributed access node. In the former case (handover within the CU), the network slice to network slice AS group mapping can be sent to the first distributed unit as part of or together with the context modification request of the terminal device. In the latter case (handover between CUs), the network slice to network slice access stratum group mapping can be sent to the first central unit as part of or together with the handover request confirmation. Subsequently, the first central unit of the first distributed access node also sends the network slice to network slice access stratum group mapping of the second cell to the first distributed unit, e.g., included in the context modification request of the terminal device. In either case, the network slice to network slice access stratum group mapping of the second cell can ultimately be communicated to the terminal device.

[0067] In some embodiments, after block 301 and before reaching block 302, the apparatus also determines whether the first cell and the second cell are configured with different network slice to network slice access stratum group mappings or at least potentially different network slice to network slice access stratum group mappings, as will be described in detail below. The transmission in block 302 can be performed only in response to the first cell and the second cell being configured with different network slice to network slice access stratum group mappings or at least potentially different network slice to network slice access stratum group mappings. This provides the benefit of avoiding or at least minimizing redundant transmissions.

[0068] In some embodiments, Figure 3 the flow can be applied to a non - distributed RAN architecture. The provisions discussed apply to this case with the necessary modifications. That is, in such an embodiment, the flow can be performed by an access node or a device for the access node, where the access node corresponds to the target (or second) access node of the handover process and provides the second cell. Further, in block 302, the access node can send the network slice to network slice AS group mapping of the second cell to the source or serving (or first) access node (which also sends the network slice to network slice AS group mapping of the second cell to the terminal device).

[0069] In other words, in such a non - distributed RAN - based embodiment, in block 301, the apparatus (for the second access node) determines that a handover of the terminal device from the first cell provided by the first access node to the second cell provided by the second access node is to be performed, and in block 302, sends the network slice to network slice access stratum group mapping of the second cell to the first access node.

[0070] Figure 4shows a process of receiving and considering the network slice to network slice AS group mapping of a target cell in the RACH resource allocation during a handover process according to an embodiment. The shown process can be executed after performing Figure 3 the process of. The shown process can be executed by a terminal device or a part thereof or a device connected thereto (i.e., a device for the terminal device). The terminal device can correspond to Figure 1 any of the terminal devices 100, 102 in and / or Figure 2 any of the terminal devices 221, 222, 223 in. Hereinafter, for the sake of simplicity, the participants in the process are simply referred to as devices.

[0071] See Figure 4 , in block 401, the device receives the network slice to network slice access stratum group mapping of a second cell that is a target cell of a handover from a first radio access network (RAN) node. Here, the second cell is assumed to be provided by a second RAN node. Similar to that described in connection with Figure 3 , the handover can be an intra-CU or inter-CU handover from a first cell to a second cell. Alternatively, the handover can be a handover between non-distributed access nodes (or a handover between a distributed access node and a non-distributed access node).

[0072] The first RAN node and the second RAN node discussed in the previous paragraphs can be defined as follows. The first RAN node can be a first (non-distributed) access node or a first distributed unit of a first distributed access node. In addition, the second RAN node can be a second (non-distributed) access node, a second distributed unit of a first distributed access node, or a second distributed unit of a second distributed access node.

[0073] In some embodiments, in block 401, the device can receive the network slice to network slice access stratum group mapping of the second cell as part of an RRC reconfiguration message or together with an RRC reconfiguration message. The RRC reconfiguration message can (also) include a handover command for performing a handover from a first cell to a second cell. The RRC reconfiguration message can also include one or more reserved or allocated RACH resources for the terminal device (defined using a context step process performed between a central unit and a target distributed unit).

[0074] In block 402, the device determines the network slice AS group for accessing the second cell based on the network slice to network slice AS group mapping of the second cell.

[0075] In block 403, the device selects (or allocates) (network slice AS group specific) RACH resources for accessing the second cell based at least on the network slice AS group. In some embodiments, multiple RACH resources can be selected in block 403.

[0076] Subsequently, in block 404, the device accesses the second cell using the (multiple) said RACH resources.

[0077] Figure 5 Another process according to an embodiment is shown, which is used to receive and consider the network slice to network slice AS group mapping of the target cell in the RACH resource selection during the handover process. The process shown can be performed after Figure 3 the execution of the process of. The process shown can be executed by the terminal device or a part thereof or a device connected thereto (i.e., the device of the terminal device). The terminal device can correspond to Figure 1 any of the terminal devices 100, 102 and / or Figure 2 any of the terminal devices 221, 222, 223 in. Hereinafter, for the sake of brevity, the participants in this process are simply referred to as devices.

[0078] Figure 5 The process of can largely correspond to Figure 4 the process of. That is, Figure 5 blocks 502, 504, 505, 506 in can respectively correspond to blocks 401 to 404 with necessary modifications, so for the sake of brevity, they will not be discussed in detail below.

[0079] Referring to Figure 5 , in block 501, it is initially assumed that the device maintains, in at least one memory, an initial network slice to network slice AS group mapping for the initial access or re - establishment to the second cell (e.g., the RA process during the initial access). During a previous handover involving the second cell, the said initial network slice to network slice access stratum group mapping may have been received, for example, as part of an RRC re - configuration message. Alternatively, the initial network slice to network slice AS group mapping may have been received by the NAS.

[0080] In response to receiving the (new) network slice to network slice AS group mapping of the second cell in block 502, in block 503, the device performs one of two possible operations. According to the first option, in block 503, the device rewrites the initial network slice to network slice AS group mapping with the network slice to network slice AS group mapping in at least one memory. According to the second option, in block 503, the device deletes (or discards or removes) the initial network slice to network slice AS group mapping (and optionally stores the received network slice to network slice AS group mapping in at least one memory).

[0081] Thereafter, the process is as described above in connection with Figure 4The operations are as follows. That is, in block 504, the apparatus determines a network slice AS group for accessing a second cell based on the network slice to network slice AS group mapping of the (newly received) second cell. In block 505, it selects a RACH resource for accessing the second cell based on the network slice AS group, and in block 506, it accesses the second cell using the RACH resource.

[0082] Figure 6 A flow according to an embodiment is shown. As part of a CU-internal handover process, this flow is used to convey, when considered necessary or at least beneficial, the network slice to network slice AS group mapping of a target cell (herein referred to as the second cell) to a terminal device via a source distributed unit (herein referred to as the first distributed unit), and to select a RACH resource based on the network slice to network slice AS group mapping. Specifically, Figure 6 Signaling between a terminal device, a first distributed unit of a distributed access node, a second distributed unit of the distributed access node, and a central unit of the distributed access node (or specifically its CU-CP entity) is shown. From the perspective of the handover process, the first distributed unit can be referred to as the source (or serving) distributed unit, while the second distributed unit can be referred to as the target distributed unit. The terminal device can correspond to Figure 1 any of the terminal devices 100, 102 and / or Figure 2 any of the terminal devices 221, 222, 223. The first and second distributed units can correspond to Figure 1 the distributed unit 104 and / or Figure 2 the distributed unit 220. The central unit can correspond to Figure 1 the central unit 108 and / or Figure 2 the central unit 230.

[0083] Refer to Figure 6 , in block 601, it can first be assumed that the central unit (or CU-CP) knows the network slice to network slice AS group mapping of the terminal device in the first cell (i.e., the serving cell) provided by the first distributed unit. In other words, in block 601, in at least one memory, the central unit can maintain the network slice to network slice AS group mapping of the terminal device in the first cell. The first distributed unit can previously send the network slice to network slice AS group mapping of the terminal device in the first cell to the central unit.

[0084] The handover process can be initiated by the terminal device sending a measurement report to the first distributed unit in message 602. In block 603, after receiving the measurement report, the first distributed unit also sends the measurement report to the central unit in message 604. In block 605, the central unit receives the measurement report.

[0085] In block 606, based at least on the measurement report, the central unit determines that a handover for the terminal device from the first cell to the second cell provided by the second distributed unit should be performed, and thus a network slice specific RACH configuration (i.e., selection of network slice or network slice AS group specific RACH resources) for the terminal device is required. The first cell and the second cell may be adjacent cells.

[0086] The central unit sends a context establishment request associated with the terminal device context of the terminal device to the second distributed unit in message 607. The context establishment request includes information on one or more network slice specific data radio bearers (DRBs) to be provided for the terminal device (e.g., DRB1 for network slice 1 and DRB2 for network slice 2). The context establishment request may be a UE context establishment request.

[0087] In block 608, after receiving the context establishment request, the second distributed unit sends a context establishment response to the central unit in message 609. The context setting response includes information on one or more network slice AS group specific RACH configurations for one or more network slices associated with the terminal device (e.g., RACH configuration of network slice AS group 1 for network slice 1 and RACH configuration of network slice AS group 2 for network slice 2). The context establishment response may be a UE context establishment response. In other words, the second distributed unit may configure or reserve or allocate one or more RACH resources (e.g., preambles and / or time / frequency information) for the handover based on the context establishment request, and send the information to be included in the context establishment response back to the central unit in message 609.

[0088] In block 610, after receiving the context establishment response, in block 611, the central unit determines that the first cell and the second cell are configured with different network slice to network slice AS group mappings, or in some cases are configured with at least potentially different network slice to network slice access stratum group mappings. Potentially different network slice to network slice AS group mappings may here mean an increased (but not certain) likelihood that the first cell and the second cell employ different network slice to network slice AS group mappings. The determination in block 611 may be based on, for example, the tracking areas of the first distributed unit and the second distributed unit. Four alternative detailed implementations of block 611 are discussed in detail below in conjunction with Figure 7 Four alternative detailed implementations of block 611 are discussed in detail.

[0089] If it is determined that the first cell and the second cell are not configured with different network slice to network slice AS group mappings, or in some cases are not even configured with potentially different network slice to network slice AS group mappings ( Figure 6If not shown in the figure (not shown), the handover process within the CU can be performed in a conventional manner until completion (without communicating the network slice of the second cell to the network slice AS group to the terminal device).

[0090] The central unit sends a context modification request (or terminal device context modification request) associated with the terminal device context of the terminal device to the first distributed unit in message 612. The (terminal device) context modification request includes an RRC message, and the RRC message includes a handover command. The mapping of the network slice of the second cell to the network slice AS group is included in the context modification request as part of the RRC message or as a separate information element. The context modification request can be a UE context modification request message.

[0091] In block 613, after receiving the context modification request, the first distributed unit sends a context modification response to the central unit in message 614. The context modification response is used to confirm the successful reception of the context modification request. The context modification response can be a UE context modification completion message. In block 615, the central unit receives the context modification response.

[0092] The first distributed unit also sends an RRC reconfiguration message to the terminal device in message 616. The RRC reconfiguration message includes: a handover command, and the mapping of the network slice of the second cell to the network slice AS. The RRC reconfiguration message may also include one or more reserved or allocated RACH resources. The RRC reconfiguration message can be an "RRCReconfiguration" message.

[0093] In some alternative embodiments, message 616 can be sent before message 614.

[0094] In some alternative embodiments, the RRC reconfiguration message 616 may include a handover command but not the mapping of the network slice of the second cell to the network slice AS group. In such an embodiment, the mapping of the network slice of the second cell to the network slice AS group can be sent from the first distributed unit to the terminal device separately from the RRC reconfiguration message (e.g., as a separate RRC message).

[0095] The operations associated with elements 617 to 620 can exactly correspond to the operations described in connection with Figure 4 boxes 401 to 404 above, and thus for the sake of brevity, they will not be repeated here. In some embodiments, one or more additional features discussed in connection with Figure 5 can also be implemented here.

[0096] Figure 7shows a process according to an embodiment for determining whether there is a difference between the network slice to network slice AS group mappings of a first cell and a second cell (i.e., a source cell and a target cell) involved in a handover process. Specifically, Figure 7 shows four alternative processes for performing Figure 6 box 611. Figure 7 shows the signaling between the central unit (or specifically its CU-CP entity) of a distributed access node and the AMF entity of the core network. The central unit can correspond to Figure 1 the central unit 108 of Figure 2 and / or Figure 1 the central unit 230 of

[0097] According to the first option, in box 711, in at least one memory, the central unit is assumed to initially maintain at least configuration information about the first cell and the second cell (i.e., the cells involved in the handover). Specifically, the configuration information at least includes: information about the tracking areas of the first cell and the second cell.

[0098] In box 712, the central unit determines, based on the configuration information, that the first cell and the second cell are under different tracking areas. Based on this determination, the central unit can determine that the network slice to network slice AS group mapping of the second cell should be communicated to the terminal device (as described above in connection with Figure 6 elements 612 to 617).

[0099] It should be noted that the fact that the first cell and the second cell are under different tracking areas does not necessarily mean that the network slice to network slice AS group mappings associated with the first cell and the second cell are different. However, since the mapping of (multiple) network slices to (multiple) network slice AS groups may be tracking area specific, the network slice to network slice AS group mappings associated with the first and second cells may or even are likely to be different.

[0100] According to the second option, in block 721, in at least one memory, the central unit is assumed to initially maintain at least configuration information about the second cell (i.e., the target cell). Specifically, the configuration information at least includes: information about the tracking area of the second cell. Alternatively, the configuration information of the first cell can also be maintained in at least one memory.

[0101] The AMF sends the registration area information of the terminal device to the central unit in message 722. The central unit receives the registration area information of the terminal device in box 723.

[0102] Then, in block 724, the central unit determines that the tracking area of the second cell does not belong to the registration area of the terminal device. Based on this determination, the central unit can determine that the network slice to network slice AS group mapping of the second cell should be communicated to the terminal device (as described above in connection with Figure 6 the components 612 to 617).

[0103] According to the third option, in block 731, the central unit is assumed to initially maintain the configuration information of the second cell in at least one memory. Specifically, the configuration information includes at least: information on the network slice to network slice AS group mapping of the second cell.

[0104] The AMF sends, in message 732, one or more network slice to network slice AS group mappings for one or more tracking areas within the registration area of the terminal device. Since the one or more network slice to network slice AS group mappings are related to one or more tracking areas within the registration area of the terminal device, they can be assumed to have been configured for the terminal device. In block 733, the central unit receives the one or more network slice to network slice AS group mappings.

[0105] In block 734, the central unit determines, based on the configuration information and the one or more network slice to network slice AS group mappings (or at least one of them), that the current network slice to network slice AS group mapping of the terminal device is different from the network slice to network slice AS group mapping of the second cell. The current network slice to network slice AS group mapping of the terminal device is assumed to be included in the one or more network slice to network slice AS group mappings received in block 733. Based on this determination, the central unit can determine that the network slice to network slice AS group mapping of the second cell should be communicated to the terminal device (as described above in connection with Figure 6 the components 612 to 617).

[0106] According to the fourth option, in block 741, in at least one memory, the central unit is assumed to initially maintain the configuration information of the first and second cells. Specifically, the configuration information includes at least: information on the network slice to network slice AS group mappings of the first and second cells.

[0107] In block 742, the central unit determines that the network slice to network slice AS group mapping of the first cell is different from the network slice to network slice AS group mapping of the second cell.

[0108] In some embodiments, one or more of the four options discussed in connection with Figure 7 can be combined.

[0109] In some embodiments, at least some of the messages 722, 732 can be sent by a core network node or entity other than the AMF.

[0110] Figure 8 shows a process as part of an inter-CU handover process, which is used to convey the network slice to network slice AS group mapping of a target cell (hereinafter referred to as the second cell) to a terminal device via a source distributed unit (hereinafter referred to as the first distributed unit) when needed or at least beneficially, and select RACH resources based on the network slice to network slice AS group mapping. Specifically, Figure 8 shows the signaling between a terminal device, a first distributed unit of a first distributed access node, a second distributed unit of a second distributed access node, a first central unit (or specifically its CU-CP entity) of the first distributed access node, and a second central unit (or specifically its CU-CP entity) of the second distributed access node. From the perspective of the handover process, the first distributed unit can be referred to as the source (or serving) distributed unit, while the second distributed unit can be referred to as the target distributed unit. The terminal device can correspond to Figure 1 any of the terminal devices 100, 102 and / or Figure 2 any of the terminal devices 221, 222, 223. The first distributed unit and the second distributed unit can correspond to Figure 1 the distributed unit 104 and / or Figure 2 the distributed unit 220. The first central unit and the second central unit can correspond to Figure 1 the central unit 108 and / or Figure 2 the central unit 230.

[0111] Referring to Figure 8 in block 801, it can be first assumed that the second central unit (or CU-CP) knows the network slice to network slice AS group mapping of the terminal device in the first cell (i.e., the serving cell) provided by the first distributed unit. In other words, in block 801, the second central unit can maintain the network slice to network slice AS group mapping of the terminal device in the first cell (i.e., the network slice to network slice AS group mapping of the first cell) in at least one memory. The first central unit can previously send the network slice to network slice AS group mapping of the terminal device in the first cell to the second central unit.

[0112] The handover process can be initiated by the terminal device sending a measurement report to the first distributed unit in message 802. After receiving the measurement report in block 803, the distributed unit also sends the measurement report to the first central unit in message 804. The transmission of message 804 can correspond to the uplink RRC message transmission.

[0113] In block 805, after receiving a measurement report, in block 806, the first central unit determines that an inter-CU handover for the terminal device from a first cell provided by a first distributed unit of a first distributed access node to a second cell provided by a second distributed unit of a second distributed access node should be performed, where the first cell and the second cell may be neighboring cells. Accordingly, the first central unit sends a handover request in message 807 to the second central unit of the second distributed access node.

[0114] In block 808, the second central unit receives the handover request from the first central unit. Based on the handover request, in block 809, the second central unit determines that an inter-CU handover for the terminal device from the first cell to the second cell is to be performed, and thus a network slice specific RACH configuration for the terminal device is required.

[0115] The second central unit and the second distributed unit perform the (terminal device) context establishment process in elements 810 to 813 in a similar (or identical) manner as described for elements 607 to 610 in connection with the central unit and the second distributed unit before. Figure 6 In block 814, the second central unit determines that the first cell and the second cell are configured with different network slice to network slice AS group mappings, or in some cases are configured with at least potentially different network slice to network slice access stratum group mappings. This determination can be made in a manner similar to that described above in connection with

[0116] and / or Figure 6 and / or Figure 7 for the intra-CU handover scenario. Specifically, Figure 7 options 1, 2, and 3 of Figure 7 also apply to this inter-CU handover scenario with necessary modifications. However, regarding Figure 7 option 2 of

[0117] it should be noted that information about the registration area of the terminal device can be sent to the second central unit by the first central unit in this case, for example, in the handover request or in a separate or dedicated message, rather than being sent directly to the second central unit by the AMF. The first central unit may have previously received information about the registration area of the terminal device from the AMF, similar to that described in connection with Figure 7 message 722 of

[0117] Figure 8 If it is determined that the first cell and the second cell are not configured with different network slice to network slice access stratum group mappings, or in some cases are not even configured with potentially different network slice to network slice access stratum group mappings (not shown in Figure 8 ), then the inter-CU handover process can be performed in a conventional manner until completion (without communicating the network slice to network slice AS group of the second cell to the terminal device).

[0118] In response to or following the determination in block 814, the second central unit sends a handover request confirmation to the first central unit in message 815. The handover request confirmation includes at least the network slice to network slice AS group mapping of the second cell or an RRC message including the network slice to network slice AS group mapping of the second cell. The first central unit receives the handover request confirmation in block 816.

[0119] The first central unit and the first distributed unit perform the (terminal device) context modification process in elements 817 to 820 in a similar (or identical) manner as described previously in connection with Figure 6 elements 612 to 615 for the central unit and the first distributed unit.

[0120] The first distributed unit also sends an RRC reconfiguration message to the terminal device in message 821. The RRC reconfiguration message includes: a handover command, and the network slice to network slice access stratum group mapping of the second cell. The RRC reconfiguration message may also include one or more reserved or allocated RACH resources for the terminal device determined using the context establishment process.

[0121] In some alternative embodiments, message 821 may be sent before message 819.

[0122] In some alternative embodiments, the RRC reconfiguration message 821 may include a handover command but not the network slice to network slice AS group mapping of the second cell. In such an embodiment, the network slice to network slice AS group mapping of the second cell may be sent from the first distributed unit to the terminal device separately from the RRC reconfiguration message (e.g., as a separate RRC message).

[0123] The operations associated with element 822 may exactly correspond to the operations described previously in connection with Figure 4 blocks 401 to 404 (and / or the operations shown in connection with Figure 6 elements 617 to 620), and thus are not repeated here for the sake of brevity. In some embodiments, one or more additional features discussed in connection with Figure 5 may also be implemented here.

[0124] Although Figure 8An embodiment based on CU - to - CU handover is shown, where the first access node and the second access node are distributed access nodes. However, in other embodiments, the first access node and / or the second access node may be non - distributed access nodes. In such embodiments, elements 804, 805, 810 to 813, 817 to 820 (related to DU - CU communication) may be omitted, and thus only operations related to elements 803, 806, 807, 816, 821 can be performed by the first non - distributed access node, and only operations related to elements 801, 808, 809, 814, 815 can be performed by the second non - distributed access node.

[0125] The above - mentioned embodiments provide at least the following advantages:

[0126] · The network can configure network - slice - specific RACH resources for terminal devices in a non - decomposed or decomposed architecture.

[0127] · RACH configuration may be considered during handover decision - making at the RAN node for guaranteeing user SLA through network - slice - specific RACH configuration awareness.

[0128] As described above through Figures 3 to 8 The blocks, related functions, and information exchanges (messages) described do not have an absolute time sequence, and some of them can be executed simultaneously or in an order different from the given order. Other functions can also be executed between or within them, and other information and / or other rules of applications can be sent. Some blocks or partial blocks or one or more pieces of information can also be omitted, or replaced by corresponding blocks or partial blocks or one or more pieces of information.

[0129] Figure 9 Apparatus 901 for a central unit (CU) of a distributed access node (e.g., a distributed gNB) according to some embodiments is provided. Specifically, Figure 9 An apparatus for the central unit can be shown, which is configured to perform at least the above - mentioned functions related to communication of network - slice - to - network - slice AS group mapping during CU - in or CU - to - CU handover. Apparatus 901 can be the central unit or the CU - CP entity of the central unit, or form a part of the central unit or the CU - CP entity. The central unit discussed can be Figure 1 the central unit 108 of Figure 2 the central unit 230 of Figures 3 to 5 and / or any central unit (including the first CU and / or the second CU) in any of them. The central unit can include a control plane entity (CU - CP) and a user plane entity (CU - UP). The operations of the central unit described in conjunction with the embodiments can be performed entirely or mainly through the control plane entity.

[0130] Apparatus 901 may include one or more control circuitry 920, such as at least one processor, and at least one memory 930. The at least one memory 930 includes one or more algorithms 931, such as computer program code (software), where the at least one memory and the computer program code (software) are configured to, together with the at least one processor, cause the apparatus 901 to perform any of the example functions of the above-mentioned central unit (or CU-CP or apparatus for the central unit). The at least one memory 930 may further include at least one database 932.

[0131] Reference Figure 9 , one or more communication control circuitry 920 of the apparatus 901 at least includes a CU switching circuitry 921. The CU switching circuitry 921 is configured to perform switching-related functions, and the switching-related functions include communication of network slice to network slice AS group mapping (of the target cell). To this end, the CU switching circuitry 921 of the apparatus 901 is configured to use one or more separate circuitry to perform at least some of the functions of the above-mentioned central unit (or CU-CP or apparatus for the central unit), for example, by Figure 3 elements 301, 302, Figure 6 elements 601, 605 to 607, 610 to 612, 615, Figure 7 elements 711, 712, 721, 723, 724, 731, 733, 734, 741, 742 and / or Figure 8 any one of the elements 801, 805 to 810, 813 to 817, 820 of

[0132] Reference Figure 9 , the apparatus 901 may further include different interfaces 910, such as one or more communication interfaces (TX / RX), which include hardware and / or software for implementing a communication connection according to one or more communication protocols. Specifically, one or more communication interfaces 910 may include, for example, an interface providing a connection to the Internet and the core network of a wireless communication network (e.g., to the AMF therein). For example, one or more communication interfaces 910 may provide the apparatus 901 (and the central unit) with communication capabilities to communicate in a cellular communication system and enable communication with user equipment (terminal equipment) and different network nodes or elements, and / or the communication interfaces may enable communication between different network nodes or elements (e.g., one or more distributed units). One or more communication interfaces 910 may include, for example, one or more F1 interfaces (e.g., one or more FI-U and / or F1-C interfaces), one or more Xn interfaces, and one or more NG interfaces.

[0133] Figure 10Apparatus 1001 for a terminal device according to some embodiments is provided. Specifically, Figure 10 Apparatus 1001 for a terminal device may be shown, which is configured to perform at least the above functions, which are related to considering network handover of a target cell or network slice AS group mapping when selecting RACH resources related to handover. Apparatus 1001 may be a terminal device or form part of a terminal device. The terminal device under discussion may be Figure 1 any one of terminal devices 100, 102 in Figure 2 and / or any one of terminal devices 221 to 223 in

[0134] Apparatus 1001 may include one or more control circuitry 1020, such as at least one processor, and at least one memory 1030. The at least one memory 1030 includes one or more algorithms 1031, such as computer program code (software), where the at least one memory and the computer program code (software) are configured to, together with the at least one processor, cause apparatus 1001 to perform any exemplary function of the above terminal device (and apparatus for a terminal device). The at least one memory 1030 may further include at least one database 1032.

[0135] Referring to Figure 10 , one or more communication control circuitry 1020 of apparatus 1001 includes at least a RACH resource selection circuitry 1021 for selecting RACH resources related to handover. To this end, the RACH resource selection circuitry 1021 of apparatus 1001 is configured to use one or more separate circuitry to perform at least some functions of the above terminal device (or apparatus for a terminal device), for example, by Figure 4 elements 401 to 404, elements 501 to 506 of Figure 6 elements 602, 617 to 620 of Figure 8 and / or any element of elements 802, 822 of

[0136] Referring to Figure 10, the apparatus 1001 may also include different interfaces 1010, such as one or more communication interfaces (TX / RX), which include hardware and / or software for implementing a communication connection according to one or more communication protocols. Specifically, the one or more communication interfaces 1010 may include, for example, an interface that provides a connection to the Internet and the core network of a wireless communication network (via one or more distributed and / or non-distributed access nodes). The one or more communication interfaces 1010 may provide the apparatus 1001 (and thus the terminal device) with communication capabilities to communicate in a cellular communication system and enable communication between user devices (terminal devices) and between different network nodes or elements (e.g., one or more distributed and / or non-distributed access nodes).

[0137] Figure 11 An apparatus 1101 for a (non-distributed or monolithic) access node (e.g., a non-distributed or monolithic gNB) according to some embodiments is provided. Specifically, Figure 11 An apparatus for an access node may be shown, which is configured to perform at least the above-described functions related to communication of network slice to network slice AS group mapping during handover. The apparatus 1101 may be an access node or form part of an access node. The access node unit under discussion may be Figure 1 the access node 104.

[0138] The apparatus 1101 may include one or more control circuitry 1120, such as at least one processor, and at least one memory 1130. The at least one memory 1130 includes one or more algorithms 1131, such as computer program code (software), where the at least one memory and the computer program code (software) are configured to, together with the at least one processor, cause the apparatus 1101 to perform any of the example functions of the above-described (non-distributed) access node. The at least one memory 1130 may also include at least one database 1132.

[0139] Referring to Figure 11 , one or more communication control circuitry 1120 of the apparatus 1101 includes at least a handover circuitry 1121, which is configured to perform at least some of the above functions using one or more separate circuitry, e.g., by Figure 3 elements 301 to 302 of Figure 7 blocks 711, 712, 721, 723, 724, 731, 733, 734, 741, 742 and / or any one of the elements 801, 803, 806, 807, 808, 809, 814, 815, 816, 821 of

[0140] Referring to Figure 11, the apparatus 1101 may further include different interfaces 1110, such as one or more communication interfaces (TX / RX), which include hardware and / or software for implementing a communication connection according to one or more communication protocols. Specifically, the one or more communication interfaces 1110 may include, for example, an interface providing a connection to the Internet and the core network of a wireless communication network. For example, the one or more communication interfaces 1110 may provide communication capabilities for the apparatus (and access nodes) to communicate in a cellular communication system and enable communication between user equipment (terminal devices) and different network nodes or elements (e.g., other access nodes) and / or communication interfaces to enable communication between different network nodes or elements.

[0141] Reference Figures 9 to 11 In any of, the memories 930, 1030, 1130 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Additionally or alternatively, Figures 9 to 11 one or more communication interfaces 910, 1030, 1130 in any of may include standard well-known components, such as amplifiers, filters, frequency converters, (de)modulators and encoder / decoder circuitry controlled by a respective control unit, and one or more antennas.

[0142] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a pure hardware circuit implementation, e.g., an implementation using only analog and / or digital circuitry, and (b) a combination of hardware circuitry and software (and / or firmware), e.g., as applicable: (i) a combination of (multiple) analog and / or digital hardware circuitry and software / firmware, and (ii) (multiple) hardware processors and software in any part, including (multiple) digital signal processors, software, and memory, which work together to cause a device (e.g., a terminal device or an access node) to perform various functions, and (c) (multiple) hardware circuits and (multiple) processors, e.g., (multiple) microprocessors or a part of (multiple) microprocessors, which require software (e.g., firmware) to operate, but the software may not be present when not needed. This definition of "circuitry" applies to all uses of the term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" also encompasses an implementation of only a hardware circuit or a processor (or multiple processors) or a part of a hardware circuit or a processor and its (or their) attendant software and / or firmware. For example, if applicable to a particular claim element, the term "circuitry" also encompasses a baseband integrated circuit for an access node or a terminal device or other computing or network device.

[0143] In an embodiment, in combination withFigures 3 to 8 At least some of the described processes may be performed by a device including corresponding components for performing at least some of the processes. Some example components for performing these processes may include at least one of the following: a detector, a processor (including dual-core and multi-core processors), a digital signal processor, a controller, a receiver, a transmitter, an encoder, a decoder, a memory, a RAM, a ROM, software, firmware, a display, a user interface, display circuitry, user interface circuitry, user interface software, display software, circuitry, an antenna, antenna circuitry, or circuitry. In an embodiment, at least one processor, memory, and computer program code form a processing component or include one or more portions of computer program code for performing one or more operations in accordance with Figures 3 to 8 any embodiment of or its operation.

[0144] According to one aspect, there is provided a device (e.g., a terminal device or a part thereof) including components for performing the following:

[0145] Receiving, from a first radio access network node, a network slice to network slice access stratum group mapping of a second cell that is a target cell of a handover, where the second cell is provided by a second radio access network node;

[0146] Determining a network slice access stratum group for accessing the second cell based on the network slice to network slice access stratum group mapping of the second cell;

[0147] Selecting a random access channel resource for accessing the second cell based on the network slice access stratum group; and

[0148] Accessing the second cell using the random access channel resource.

[0149] According to one aspect, there is provided a device (e.g., a central unit of a distributed access node or a part thereof) including components for performing the following:

[0150] Determining that an in-central-unit handover or an inter-central-unit handover of a terminal device from a first cell provided by a first distributed unit to a second cell provided by a second distributed unit is to be performed;

[0151] In the case of an in-central-unit handover, directly sending the network slice to network slice access stratum group mapping of the second cell to the first distributed unit, or in the case of an inter-central-unit handover, sending the network slice to network slice access stratum group mapping of the second cell to the first distributed unit via a first central unit.

[0152] According to one aspect, there is provided a device (e.g., an access node or a part thereof) including components for performing the following:

[0153] It is determined that a handover of a terminal device from a first cell provided by a first access node to a second cell provided by a second access node is to be performed; and

[0154] Send a network slice to network slice access stratum group mapping of the second cell to the first access node.

[0155] The embodiments may also be implemented in the form of a computer process defined by a computer program or a part thereof. In combination Figures 3 to 8 The method embodiments described above may be implemented by executing at least a part of a computer program including corresponding instructions. The computer program may be provided as a computer-readable medium including program instructions stored thereon or a non-transitory computer-readable medium including program instructions stored thereon. The computer program may be in source code form, object code form or some intermediate form, and may be stored in some carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer program distribution medium readable by a computer or a processor. For example, the computer program medium may be, for example but not limited to, a recording medium, a computer memory, a read-only memory, an electrical carrier signal, a telecommunication signal and a software distribution package. The computer program medium may be a non-transitory medium. The software coding for implementing the illustrated and described embodiments is entirely within the knowledge of those of ordinary skill in the art.

[0156] Although the embodiments have been described above with reference to examples according to the drawings, it is obvious that the embodiments are not limited thereto, but can be modified in various ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate the embodiments rather than limit the embodiments. It is obvious to those skilled in the art that, with the progress of technology, the inventive concept can be implemented in various ways. In addition, it is obvious to those skilled in the art that the described embodiments may but need not be combined with other embodiments in various ways.

Claims

1. A device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least perform: receive, from a first radio access network node, a network slice to network slice access stratum group mapping of a second cell that is a target cell for handover, wherein the second cell is provided by a second radio access network node; determine a network slice access stratum group for accessing the second cell based on the network slice to network slice access stratum group mapping of the second cell; select a random access channel resource for accessing the second cell based on the network slice access stratum group; and use the random access channel resource to access the second cell.

2. The device according to claim 1, wherein the first radio access network node is a first access node, or a first distributed unit of a first distributed access node, and / or the second radio access network node is a second access node, or a second distributed unit of the first distributed access node or a second distributed access node.

3. The device according to claim 1 or 2, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to perform the receiving of the network slice to network slice access stratum group mapping of the second cell by: Receive a Radio Resource Control (RRC) reconfiguration message, the RRC reconfiguration message including: a handover command, and the network slice to network slice access stratum group mapping of the second cell.

4. The device according to any one of the preceding claims, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to further perform: In the at least one memory, before the reception, maintain an initial network slice to network slice access stratum group mapping for initial access to or re-establishment of the second cell; and in response to the receiving of the network slice to network slice access stratum group mapping, rewrite the initial network slice to network slice access stratum group mapping using the network slice to network slice access stratum group mapping; or in response to the receiving of the network slice to network slice access stratum group mapping, delete the initial network slice to network slice access stratum group mapping.

5. A device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least perform: determine that an inter-central unit handover or an intra-central unit handover of a terminal device from a first cell provided by a first distributed unit to a second cell provided by a second distributed unit is to be performed; and in the case of an intra-central unit handover, directly send the network slice to network slice access stratum group mapping of the second cell to the first distributed unit, or in the case of an inter-central unit handover, send the network slice to network slice access stratum group mapping of the second cell to the first distributed unit via a first central unit.

6. The apparatus according to claim 5, wherein the first distributed unit and the second distributed unit are distributed units of a first distributed access node, and thus the in-central-unit handover is determined to be performed, and the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: perform the sending of the network slice to network slice access stratum group mapping of the second cell at least by: send a context modification request associated with the terminal device context of the terminal device to the first distributed unit, wherein the terminal device context modification request includes a radio resource control message, the radio resource control message includes a handover request, and the network slice to network slice access stratum group mapping of the second cell is included in the context modification request as part of the radio resource control message or as a separate information element.

7. The apparatus according to claim 5, wherein the first distributed unit and the second distributed unit are distributed units of a first distributed access node and a second distributed access node respectively, and thus the inter-central-unit handover is determined to be performed, the first central unit is the central unit of the first distributed access node, and the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: perform the determination that the inter-central-unit handover is to be performed by at least receiving, from the first central unit, a handover request for the inter-central-unit handover; Performing the sending of the network slice to network slice access stratum mapping of the second cell by sending at least a handover request confirmation to the first central unit, wherein the handover request confirmation comprises: the network slice to network slice access stratum group mapping of the second cell.

8. An apparatus, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least perform: determine that a handover of a terminal device from a first cell provided by a first access node to a second cell provided by a second access node is to be performed; and send the network slice to network slice access stratum group mapping of the second cell to the first access node.

9. The apparatus according to any one of claims 5 to 8, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: perform the sending of the network slice to network slice access stratum group mapping in response to determining that the first cell and the second cell are configured with different network slice to network slice access stratum group mappings or at least potentially different network slice to network slice access stratum group mappings.

10. The apparatus according to any one of claims 5 to 8, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to further perform: In the at least one memory, configuration information regarding the first cell and the second cell is maintained, where the configuration information at least includes: the tracking areas of the first cell and the second cell; and In response to determining that the first cell and the second cell are under different tracking areas based on the configuration information, perform the sending of the mapping of the network slice to the network slice access layer group.

11. The apparatus according to any one of claims 5 to 7, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to further perform: Maintain, in the at least one memory, configuration information about the second cell, where the configuration information at least includes the tracking area of the second cell; Receive, from a core network node, information about the registration area of the terminal device in the case of a handover within the central unit, or receive, from the first central unit, information about the registration area of the terminal device in the case of a handover between central units; and In response to determining that the tracking area of the second cell does not belong to the registration area of the terminal device, perform the sending of the mapping of the network slice to the network slice access layer group.

12. The apparatus according to any one of claims 5 to 7, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to further perform: In the at least one memory, configuration information regarding the second cell is maintained, where the configuration information at least includes: Mapping of the network slice of the second cell to the network slice access layer group; Receive, from a core network node, one or more mappings of the network slice to the network slice access layer group for one or more tracking areas within the registration area of the terminal device; and And In response to determining that the current mapping of the network slice of the terminal device to the network slice access layer group is different from the mapping of the network slice of the second cell to the network slice access layer group, perform the sending of the mapping of the network slice to the network slice access layer group.

13. The apparatus according to any one of claims 5 to 6, wherein the first distributed unit and the second distributed unit are distributed units of a first distributed access node, and thus it is determined that a handover within the central unit is to be performed, and the at least one memory and the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to perform: In the at least one memory, configuration information regarding the first cell and the second cell is maintained, where the configuration information at least includes: Mapping of the network slice of the first cell and the second cell to the network slice access layer group; And In response to determining that the mapping of the network slice of the first cell to the network slice access layer group is different from the mapping of the network slice of the second cell to the network slice access layer group, perform the sending of the mapping of the network slice to the network slice access layer group.

14. A method, comprising: Receive, from a first radio access network node, a mapping of the network slice of a second cell, which is a target cell of a handover, to the network slice access layer group, where the second cell is provided by a second radio access network node; Based on the mapping of the network slice of the second cell to the network slice access layer group, determine a network slice access layer group for accessing the second cell; Based on the network slice access layer group, select a random access channel resource for accessing the second cell; And Use the random access channel resource to access the second cell.

15. A method, comprising: determining that an inter-central unit handover or an intra-central unit handover of a terminal device from a first cell provided by a first distributed unit to a second cell provided by a second distributed unit is to be performed; and in the case of the intra-central unit handover, directly sending a network slice to network slice access stratum group mapping of the second cell to the first distributed unit, or in the case of the inter-central unit handover, sending the network slice to network slice access stratum group mapping of the second cell to the first distributed unit via a first central unit.

16. A computer program product embodied on a non-transitory computer-readable medium, comprising program instructions that, when running, are adapted to perform: receiving, from a first radio access network node, a network slice to network slice access stratum group mapping of a second cell that is a target cell of a handover, wherein the second cell is provided by a second radio access network node; determining, based on the network slice to network slice access stratum group mapping of the second cell, a network slice access stratum group mapping for accessing the second cell; selecting, based on the network slice access stratum group, a random access channel resource for accessing the second cell; and using the random access channel resource to access the second cell.

17. A computer program product embodied on a non-transitory computer-readable medium, comprising program instructions that, when running, are adapted to perform: determining that an inter-central unit handover or an intra-central unit handover of a terminal device from a first cell provided by a first distributed unit to a second cell provided by a second distributed unit is to be performed; and in the case of the intra-central unit handover, directly sending a network slice to network slice access stratum group mapping of the second cell to the first distributed unit, or in the case of the inter-central unit handover, sending the network slice to network slice access stratum group mapping of the second cell to the first distributed unit via a first central unit.

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