Radio terminal, radio access network node, and methods for same

Abstract

This radio terminal provides a layer 2 according to a specific radio access technology in order to transmit or receive Protocol Data Unit (PDU) layer PDUs to or from a radio access network via a physical layer according to the specific radio access technology. In one example, the wireless terminal determines whether to include a Radio Link Control (RLC) sublayer in the layer 2 on the basis of at least one of a data radio bearer, a Quality of Service (QoS) flow, a PDU session, a use case, or a device type. This allows, for example, a flexible change or adaptation of the layer 2 structure or protocol stack of a radio interface between the radio terminal and the radio access network.

Description

Wireless terminal, radio access network node, and methods thereof

[0001] The present disclosure relates to wireless communication systems, and more particularly to user plane protocols in the radio interface between a wireless terminal and a radio access network.

[0002] The user plane protocol stack used in the radio interface (i.e., Uu interface) between a 3rd Generation Partnership Project (3GPP®) NR radio terminal (i.e., User Equipment (UE)) and a radio access network (i.e., gNB) includes Layer 2 (L2) and the physical (PHY) layer. Layer 2 may also be referred to as the data link layer. Layer 2 in NR is divided into four sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP) (see, for example, Sections 4.4.1 and 6 of Non-Patent Document 1).

[0003] Layer 2 of the NR Uu interface can be modified for specific applications. At the Uu interface between the L2 UE-to-Network (U2N) Relay and the gNB, the L2 U2N Relay terminates the MAC, RLC, and Sidelink Relay Adaptation Protocol (SRAP) sublayers for the Uu Relay RLC channel, but does not terminate the PDCP and SDAP sublayers (see, for example, Section 16.12 of 3GPP TS 36.100-10100). The Uu SRAP sublayer of the L2 U2N Relay is located above the Uu RLC sublayer. The Uu SRAP sublayer provides mapping between the L2 U2N Remote UE's end-to-end Uu radio bearers and egress Uu Relay RLC channels on the L2 U2N Relay UE Uu interface. In addition, the Uu SRAP sublayer supports L2 U2N Remote UE identification for uplink (UL) traffic and downlink (DL) traffic.

[0004] The IAB Mobile Termination (MT) function of an Integrated Access and Backhaul (IAB) node terminates the Uu interface to a parent node (see, for example, Sections 4.7.2 and 4.7.3 of 3GPP TS 26.2006-01004). At the Uu interface between the IAB-MT and a parent node (i.e., an IAB donor or parent IAB node), the IAB-MT terminates the MAC, RLC, and Backhaul Adaptation Protocol (BAP) sublayers for the Backhaul (BH) RLC channel, but does not terminate the PDCP and SDAP sublayers. The BAP sublayer is located above the RLC sublayer. The BAP sublayer provides packet routing and flow control in the IAB topology.

[0005] 3GPP TS 38.300 V18.2.0 (2024-06) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 18)", July 2024

[0006] The 3GPP fifth-generation mobile communication system (5G system) has introduced device types and use cases such as Reduced Capability (RedCap) UE, two-antenna port (2Rx) eXtended Reality (XR) UE, Uncrewed Aerial Vehicle (UAV), and NTN. Support for additional device types and use cases (e.g., Ambient IoT) in the 5G system is currently under discussion. Future 6G systems are expected to support a wider variety of device types and use cases. In particular, low-end IoT devices will be supported from the first release of the 6G specifications to prepare for the replacement of older 4G Category M or Narrow Band Internet of Things (NB-IoT) devices or for their use cases to be covered by other types of devices. Additionally, 6G will require much higher peak values ​​for various UE capability parameters than 5G. These parameters include peak data rate, mobility performance (e.g., movement speed), latency, and reliability. However, these peak values ​​may not need to be achieved for all use cases and device types, and certain use cases or certain device types may only support more relaxed peak values.

[0007] The 5G NR Layer 2 architecture is primarily targeted at enhanced Mobile Broadband (eMBB) type services and may not specifically address other specific requirements (e.g., ultra-low latency devices or low-performance devices). For example, for a particular use case or device type, one or more sublayers within Layer 2 may be omitted or may be desirable to be omitted. Alternatively, for a particular use case or device type, one or more functions within an L2 sublayer may be omitted or may be desirable to be omitted.

[0008] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to enabling flexible change or adaptation of the layer 2 structure or protocol stack of the radio interface between a wireless terminal and a radio access network. It should be noted that this objective is only one of multiple objectives to be achieved by multiple embodiments disclosed in this specification. Other objectives or problems and novel features will become apparent from the description of this specification or the accompanying drawings.

[0009] In a first aspect, a wireless terminal is configured to determine whether to include an RLC sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, and to provide Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0010] In a second aspect, a method performed by a wireless terminal includes: (a) determining whether to include an RLC sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type; and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0011] In a third aspect, a Radio Access Network (RAN) node is configured to determine whether to include an RLC sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type, and the RAN node is configured to provide Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a wireless terminal via a physical layer according to the specific radio access technology.

[0012] In a fourth aspect, a method performed by a RAN node includes: (a) determining whether to include an RLC sublayer in Layer 2 according to a particular radio access technology based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type; and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a wireless terminal via a physical layer according to the particular radio access technology.

[0013] In a fifth aspect, a wireless terminal is configured to determine whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type. The wireless terminal is configured to provide Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0014] In a sixth aspect, a method performed by a wireless terminal includes: (a) determining, based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type, whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or whether to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers; and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0015] In a seventh aspect, a RAN node is configured to determine whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by shifting or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type, and to provide Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a wireless terminal via a physical layer according to the specific radio access technology.

[0016] In an eighth aspect, a method performed by a RAN node includes: (a) determining, based on at least one of a data radio bearer, a QoS flow, a network slice, a PDU session, a use case, or a device type, whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or whether to use a second number of sublayers, which is less than the first number, in Layer 2 by shifting or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers; and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a wireless terminal via a physical layer according to the specific radio access technology.

[0017] In a ninth aspect, a wireless terminal is configured to provide a Layer 2 according to a specific radio access technology, the wireless terminal being configured to determine whether to enable or disable at least one function in at least one sublayer included in the Layer 2 based on one or both of a use case and a device type, the wireless terminal being configured to provide the Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0018] In a tenth aspect, a method performed by a wireless terminal includes (a) determining whether to enable or disable at least one function in at least one sublayer included in Layer 2 according to a particular radio access technology based on one or both of a use case and a device type, and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio access network via a physical layer according to the particular radio access technology.

[0019] In an eleventh aspect, a RAN node is configured to determine whether to enable or disable at least one function in at least one sub-layer comprised in Layer 2 according to a particular radio access technology based on one or both of a use case and a device type, the RAN node being configured to provide Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the particular radio access technology.

[0020] In a twelfth aspect, a method performed by a RAN node includes: (a) determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a particular radio access technology based on one or both of a use case and a device type; and (b) providing Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio terminal via a physical layer according to the particular radio access technology.

[0021] In a thirteenth aspect, a wireless terminal is configured to select, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology, the wireless terminal is configured to provide the Layer 2 for transmitting / receiving PDUs of a PDU layer to / from a radio access network via a physical layer according to the specific radio access technology.

[0022] In a fourteenth aspect, a method performed by a wireless terminal includes (a) selecting, based on one or both of a use case and a device type, a plurality of functions to be used in a Layer 2 according to a specific radio access technology from a set of predefined Layer 2 functions, and (b) providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

[0023] In a fifteenth aspect, a RAN node is configured to select, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, functions to be used in Layer 2 according to a specific radio access technology, the RAN node being configured to provide the Layer 2 for transmitting / receiving PDUs of a PDU layer to / from a radio terminal via a physical layer according to the specific radio access technology.

[0024] In a sixteenth aspect, a method performed by a RAN node includes: (a) selecting, based on one or both of a use case and a device type, a plurality of functions to be used in a Layer 2 according to a particular radio access technology from a set of predefined Layer 2 functions; and (b) providing the Layer 2 for transmitting PDU layer PDUs to or receiving PDUs from a wireless terminal via a physical layer according to the particular radio access technology.

[0025] In a seventeenth aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform a method according to any one of the above aspects.

[0026] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to enabling flexible change or adaptation of the Layer 2 structure or protocol stack of the radio interface between a radio terminal and a radio access network.

[0027] 1 illustrates an example configuration of a wireless communication system according to one or more embodiments. 2 illustrates an example user plane protocol stack according to one or more embodiments. 3 illustrates a flowchart of an example UE operation according to one or more embodiments. 4 illustrates an example Layer 2 structure or protocol stack change according to one or more embodiments. 5 illustrates an example Layer 2 structure or protocol stack change according to one or more embodiments. 6 illustrates an example Layer 2 structure or protocol stack change according to one or more embodiments. 7 illustrates an example UE operation according to one or more embodiments. 8 illustrates an example Layer 2 structure or protocol stack change according to one or more embodiments. 9 illustrates an example UE operation according to one or more embodiments. 10 illustrates an example UE operation according to one or more embodiments. 11 illustrates an example UE operation according to one or more embodiments. 12 illustrates an example UE operation according to one or more embodiments. 13 illustrates an example UE operation according to one or more embodiments. 14 illustrates an example Layer 2 structure or protocol stack change according to one or more embodiments. 15 illustrates an example UE operation according to one or more embodiments. 16 illustrates an example UE operation according to one or more embodiments. 17 illustrates an example UE operation according to one or more embodiments. 18 illustrates an example UE operation according to one or more embodiments. 19 illustrates an example UE operation according to one or more embodiments. 20 illustrates an example UE operation according to one or more embodiments. 21 illustrates an example UE operation according to one or more embodiments. 22 illustrates an example UE operation according to one or more embodiments. 23 illustrates an example UE operation according to one or more embodiments. 24 illustrates an example UE operation according to one or more embodiments. 25 illustrates an example UE operation according to one or more embodiments. 26 illustrates an example UE operation according to one or more embodiments. 27 illustrates an example UE operation according to one or more embodiments. 28 illustrates an example UE operation according to one or more embodiments. 29 illustrates an example UE operation according to one or more embodiments. 30 illustrates an example UE operation according to one or more embodiments. 31 illustrates an example UE FIG. 1 is a block diagram illustrating an example configuration of a RAN node according to one or more embodiments.

[0028] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0029] The multiple embodiments described below may be used independently, or two or more embodiments may be combined as appropriate. These multiple embodiments may have different novel features. Therefore, these multiple embodiments may contribute to achieving different objectives or solving different problems, and may contribute to achieving different effects.

[0030] Each drawing is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0031] The following embodiments are described mainly for a 3GPP mobile communication system, such as a future 3GPP Beyond 5G system or 6G system, but may also be applied to other wireless communication systems.

[0032] As used herein, depending on the context, "if" may be interpreted to mean "when," "while," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be interpreted to have the same meaning, depending on the context.

[0033] First, the configurations and operations of multiple network elements common to multiple embodiments will be described. Figure 1 shows an example configuration of a wireless communication system according to multiple embodiments. Each of the elements shown in Figure 1 is a network function, and provides an interface defined by, for example, 3GPP. Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0034] The wireless communication system shown in Fig. 1 may be provided by a Mobile Network Operator (MNO) or a Non-Public Network (NPN) provided by a party other than an MNO. If the cellular network shown in Fig. 1 is an NPN, it may be an independent network called a Stand-alone Non-Public Network (SNPN), or an NPN that works in conjunction with an MNO network called a Public network integrated NPN (PNI-NPN).

[0035] In the example of FIG. 1, the wireless communication system includes a UE 1, a RAN 2, and a core network 4. The UE 1 may be referred to by other terms, such as a wireless terminal, a mobile terminal, a mobile station, or a wireless transmit receive unit (WTRU). The RAN 2 includes one or more RAN nodes 3. The RAN nodes 3 may be referred to by other terms, such as a base station, a radio station, or an access point. The core network 4 includes one or more network functions or nodes in the control plane and one or more functions or nodes in the user plane. FIG. 1 illustrates some representative network functions or nodes in the core network 4, including an Access and Mobility Management Function (AMF) 5, a Session Management Function (SMF) 6, and a User Plane Function (UPF) 7. The UPF 7 may include multiple interconnected UPFs. More specifically, the UPF 7 includes a PDU Session Anchor (PSA) UPF and may include one or more intermediate UPFs. The intermediate UPF may provide an Uplink Classifier (UL CL) or Branching Point (BP) function.

[0036] UE 1 communicates with a Data Network (DN) 8 using connectivity services provided by the RAN 2 and the core network 4. More specifically, UE 1 is connected to a RAN node 3 in the RAN 2 and communicates with a DN 8 via a UPF 7 in the core network 4. UE 1 establishes one or more Protocol Data Unit (PDU) sessions 100 between UE 1 and the UPF 7 (i.e., PSA UPF) to which UE 1 and DN 8 are connected. The PDU session 100 is an association, session, or connection between UE 1 and DN 8. The PDU session 100 is used to provide PDU connectivity services (i.e., the exchange of PDUs between UE 1 and DN 8). From a data transfer perspective, the PDU session 100 is composed of a tunnel within the core network 4 (e.g., an N9 tunnel), a tunnel between the core network 4 and the RAN 2 (e.g., an N3 tunnel), and one or more radio bearers. Although not shown in FIG. 1, the UE 1 may establish multiple PDU sessions with multiple PDU session anchors (UPFs) 7, respectively, to access multiple DNs 8 concurrently.

[0037] Network slicing (or network slicing) enables networks (e.g., one or both of the core network 4 and the RAN 2) to individually control traffic with different attributes or customer requirements. A network slice is uniquely identified by a Single Network Slice Selection Assistance Information (S-NSSAI). The S-NSSAI may consist of a Slice / Service Type (SST) field and a Slice Differentiator (SD) field. Network slices (e.g., S-NSSAI) with similar QoS characteristics or priorities may be associated with the same group, called a Network Slice Access stratum group (NSAG).

[0038] The QoS model is based on QoS flows. The QoS model supports both QoS flows that require flow bit rate guarantees (GBR QoS flows) and QoS flows that do not require flow bit rate guarantees (Non-GBR QoS flows). QoS flows are the finest granularity of QoS differentiation within a PDU session. In other words, QoS flows are the finest granularity for QoS forwarding treatment. All traffic mapped to the same QoS flow receives the same forwarding treatment (e.g., scheduling policy, queue management policy, rate shaping, Radio Link Control (RLC) settings, etc.). To provide different QoS forwarding treatments, separate QoS flows are required.

[0039] Every QoS flow is characterized by a QoS profile; one or more QoS rules and optional QoS flow level parameters; and one or more uplink and downlink Packet Detection Rule(s) (PDR(s)). The QoS profile is provided from the SMF 6 to the RAN 2 (or RAN node 3) via the AMF 5. One or more QoS rules and QoS flow level parameters are provided from the SMF 6 to the UE 1 via the AMF 5. One or more uplink and downlink PDR(s) are provided from the SMF 6 to the UPF 7.

[0040] As shown in FIG. 1 , multiple QoS flows 120 associated with different QoS requirements can be established for one PDU session 100. One or more applications 10 in a UE 1 transmit or receive multiple packet flows to or from one or more applications 80 in a DN 8 via the multiple QoS flows 120. The DN 8 may be an Edge Data Network (EDN) or a Local Area Data Network (LADN). One or more application servers in the DN 8 may include one or more edge computing servers located near the RAN 2. In other words, the applications 80 in the DN 8 may be hosted on one or more edge computing servers located near the RAN 2.

[0041] As can be understood from the above description, a QoS flow can be considered as a packet flow between UE1 and the core network 4, which is made up of one or more packet flows transferred between UE1 and DN8. Alternatively, a QoS flow can be considered as a transmission path or connection set up or established between UE1 and the core network 4 for forwarding one or more packet flows transferred between UE1 and DN8.

[0042] The RAN node 3 provides one or more cells. The UE 1 may be simultaneously connected to multiple cells provided by the RAN node 3. In other words, the UE 1 may perform carrier aggregation (CA) between multiple cells provided by the RAN node 3. In addition, the UE 1 may be simultaneously connected to the RAN node 3 and other RAN nodes for dual connectivity (DC). This dual connectivity may be multi-radio dual connectivity (MR-DC).

[0043] The RAN node 3 may be a Central Unit (CU) in a cloud RAN (C-RAN) deployment, or a combination of a CU and one or more Distributed Units (DUs). C-RAN is also referred to as a CU / DU split. Furthermore, a CU may include a Control Plane (CP) Unit (CU-CP) and one or more User Plane (UP) Units (CU-UP). Thus, the RAN node 3 may be a CU-CP or a combination of a CU-CP and a CU-UP. The CU may be a logical node that hosts the Radio Resource Control (RRC) SDAP and PDCP protocols (or the RRC and PDCP protocols) of the RAN node. The DU may be a logical node that hosts the RLC, MAC, and PHY layers of the RAN node. The DU may host the high PHY layer, and the low PHY layer may be located in one or more Transmission-Reception Points (TRPs) connected to the DU. The TRP may also be called a Radio Unit (RU) or a Remote Radio Head (RRH).

[0044] The AMF 5 is one of the network functions in the core network control plane. The AMF 5 provides the termination of the RAN Control Plane (CP) interface (e.g., N2 interface). The AMF 5 terminates a single signaling connection (i.e., Non-Access Stratum (NAS) signaling connection) with the UE 1 and provides registration management, connection management, and mobility management. Registration management is used to register or deregister the UE 1 to the network. Connection management is used to establish and release the NAS signaling connection between the UE 1 and the AMF 5. Mobility management is used to keep track of the location of the UE 1. Mobility management uses a periodic registration update procedure and a mobility registration update procedure. Therefore, mobility management can also be said to be included in registration management.

[0045] The SMF 6 is one of the network functions in the core network control plane. The SMF 6 provides session management. The session management is used to establish, modify, and release PDU sessions to provide PDU connectivity services to the UE 1. The session management includes signaling between the UE 1, the RAN 2, the AMF 5, and the UPF 7 for establishing, modifying, and releasing PDU sessions.

[0046] The SMF 6 transmits and receives SM signaling messages to and from the NAS Session Management (SM) layer of the UE 1 via the communication service provided by the AMF 5. In addition, the SMF 6 transmits and receives SM information to and from the RAN 2 (or RAN node 3) via the communication service provided by the AMF 5. The SM information sent from the SMF 6 to the RAN 2 via the AMF 5 can include, among other information, a PDU session ID, QoS flow identifiers (QFIs) and QoS profiles of one or more QoS flows.

[0047] Figure 2 shows an example of a user plane protocol stack provided by the wireless communication system of Figure 1. UE1 and DN8 (e.g., an application server) can exchange PDUs (e.g., Internet Protocol (IP) packets) at the PDU layer. The application layer refers to a layer above the PDU layer. Thus, if the PDU layer is the IP layer, the application layer may include a transport layer protocol (e.g., Transmission Control Protocol (TCP) or User Datagram Protocol (UDP)) of the Open Systems Interconnection (OSI) model. For example, in the case of an eXtended Reality (XR) service, the PDU layer protocol may be IP, while the application layer protocol may include an H.264, H265, or H.266 codec, Real-time Transport Protocol (RTP), and UDP.

[0048] Layer 2 between the radio interface (e.g., Uu interface) between the UE 1 and the RAN node 3 may include four sublayers: MAC, RLC, PDCP, and SDAP sublayers. The physical layer provides transport channels to the MAC layer. The MAC sublayer provides logical channels to the RLC sublayer. The RLC sublayer provides RLC channels to the PDCP sublayer. The PDCP sublayer provides radio bearers to the SDAP sublayer. The SDAP sublayer provides QoS flows to the PDU layer. The main services and functions of the MAC, RLC, PDCP, and SDAP sublayers may be as follows:

[0049] The main services and functions of the MAC sublayer include: - mapping between logical channels and transport channels; - multiplexing of MAC Service Data Units (SDUs) belonging to one or different logical channels into transport blocks that are delivered to the physical layer on transport channels; - demultiplexing of MAC SDUs belonging to one or different logical channels from transport blocks that are delivered from the physical layer on transport channels; - reporting of scheduling information; - error correction through Hybrid Automatic Repeat Request (HARQ); - priority handling between UEs through dynamic scheduling; - priority handling between logical channels of one UE through logical channel prioritization; - priority handling between overlapping resources of one UE; - padding.

[0050] The RLC sublayer supports three transmission or transfer modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). The main services and functions of the RLC sublayer include: - transfer of upper layer PDUs; - sequence numbering independent of that of PDCP (UM and AM); - error correction by ARQ (AM only); - segmentation (AM and UM) and resegmentation (AM only) of RLC SDUs; - reassembly of SDUs (AM and UM); - duplicate detection (AM only); - discarding of RLC SDUs (AM and UM); - RLC re-establishment; - protocol error detection (AM only).

[0051] The main services and functions of the PDCP sublayer include: - data forwarding (user plane or control plane); - PDCP Sequence Number (SN) maintenance; - header compression and decompression using the Robust Header Compression (ROHC) protocol; - header compression and decompression using the Ethernet Header Compression (EHC) protocol; - uplink PDCP SDU compression and decompression (DEFLATE-based Uplink Data Compression (UDC) only); - ciphering and deciphering; - integrity protection and integrity verification; - timer-based SDU discarding; - routing for split bearers; - duplication; - reordering and in-order delivery; - out-of-order delivery; - duplicate discarding.

[0052] The main services and functions of the SDAP sublayer include: - mapping between a QoS flow and a data radio bearer; - marking of QoS Flow ID (QFI) in both DL and UL packets.

[0053] The examples of the network architecture, network elements, QoS model, user plane protocol stack, and technical terminology described with reference to Figures 1 and 2 may be modified as appropriate. These examples are described based on those of a 5G system. However, for example, in the case of a 6G system, those described with reference to Figures 1 and 2 may be modified to suit a 6G system that will be defined in the future. For example, the terms "PDU session," "network slice," "QoS flow," "radio bearer," "AMF," "SMF," and "UPF" may be replaced with corresponding terms in the 6G system. The QoS model described above may be modified to suit a 6G system that will be defined in the future. The main services and functions of the MAC, RLC, PDCP, and SDAP sublayers described above may be modified to suit a 6G system that will be defined in the future.

[0054] 2 shows that in the radio interface (e.g., Uu interface) between the UE 1 and the RAN node 3, Layer 2 includes four sublayers, namely, MAC, RLC, PDCP, and SDAP sublayers. For example, in a 6G system, Layer 2 in the user plane protocol stack in the Uu interface may have a structure or function different from that shown in FIG. 2. Additionally or alternatively, the structure or function of Layer 2 in the user plane protocol stack in the Uu interface may be adaptively changeable. The following embodiments provide such variations.

[0055] First Embodiment This embodiment provides an example of adaptation of the Layer 2 structure or protocol stack of the radio interface between the UE 1 and the RAN node 3. Figure 3 shows an example of the operation of the UE 1.

[0056] In step 301, UE1 determines whether to include an RLC sublayer in Layer 2 based on at least one of a Data Radio Bearer (DRB), a QoS flow, a network slice, a PDU session, a use case, or a device type. In other words, UE1 determines whether to use or omit an RLC sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. This Layer 2 is related to a specific Radio Access Technology (RAT) (e.g., 6G RAT) and is used to transmit PDUs of the PDU layer to or receive them from RAN2 via a PHY layer according to the specific RAT.

[0057] In step 302, UE1 provisions Layer 2 according to a specific RAT according to the determination in step 301. Provisioning Layer 2 may also be referred to as establishing Layer 2 or configuring Layer 2.

[0058] The UE1 may determine whether to include an RLC sublayer in Layer 2 according to at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. The UE1 may determine whether to include an RLC sublayer in Layer 2 for each DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. That is, whether the UE1 uses an RLC sublayer in a user plane protocol stack in the radio interface between the UE1 and the RAN2 may vary depending on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type.

[0059] The use case may be one of multiple predefined use cases, which may be predefined in (future) 3GPP specifications. The multiple predefined use cases may include one or any combination of eMBB, Ultra-Reliable and Low Latency Communications (URLLC), Immersive (or XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), and vehicle-to-everything (V2X).

[0060] The device type may be one of a number of predefined device types, which may be predefined in (future) 3GPP specifications, including one or any combination of a handheld device, a robotics device, a wearable device, a sensor device, and an automotive device.

[0061] UE1 may determine whether to include the RLC sublayer in Layer 2 for each of multiple QoS flows belonging to the same PDU session. In this case, whether UE1 uses the RLC sublayer in the user plane protocol stack in the radio interface between UE1 and RAN2 may differ for each of multiple QoS flows belonging to the same PDU session. This control or concept can also be applied to multiple QoS flows belonging to different PDU sessions. That is, whether UE1 uses the RLC sublayer may differ for each of multiple QoS flows belonging to different PDU sessions.

[0062] UE1 may determine whether to include the RLC sublayer in Layer 2 for each of multiple DRBs associated with the same PDU session. Therefore, whether UE1 uses the RLC sublayer in the user plane protocol stack in the radio interface between UE1 and RAN2 may differ for each of multiple DRBs associated with the same PDU session. This control or concept is also applicable to multiple DRBs associated with different PDU sessions. That is, whether UE1 uses the RLC sublayer may differ for each of multiple DRBs associated with different PDU sessions.

[0063] UE1 may determine for each network slice (e.g., S-NSSAI, NSAG) whether to include the RLC sublayer in Layer 2. Therefore, whether UE1 uses the RLC sublayer in the user plane protocol stack in the radio interface between UE1 and RAN2 may differ for each network slice.

[0064] UE1 may decide for each PDU session whether to include the RLC sublayer in Layer 2. Therefore, whether UE1 uses the RLC sublayer in the user plane protocol stack in the air interface between UE1 and RAN2 may vary for each PDU session.

[0065] The UE 1 may determine whether to include an RLC sublayer in Layer 2 based at least on an intended use case of the transmitted PDU layer PDUs. The UE 1 may determine whether to include an RLC sublayer in Layer 2 according to at least configuration information generated by the RAN 2 (e.g., RAN node 3) based on the intended use case of the transmitted PDU layer PDUs. The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration.

[0066] The UE 1 may determine whether to include an RLC sublayer in Layer 2 based at least on a device type of the UE 1. The UE 1 may determine whether to include an RLC sublayer in Layer 2 according to at least configuration information generated by the RAN 2 (e.g., RAN node 3) based on the device type of the UE 1. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration.

[0067] UE1 may determine whether to include the RLC sublayer in Layer 2 based at least on the UE capability set or at least on an identification (e.g., identification information, identifier, or index) of the UE capability set. UE1 may determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by RAN2 (e.g., RAN node 3) based on the UE capability set of UE1. The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration.

[0068] The UE capability set is associated with one or both of an intended use case from among a plurality of predefined use cases and its own device type from among a plurality of predefined device types. The UE capability set may be one of a plurality of predefined UE capability sets. Each of the plurality of predefined UE capability sets defines a respective value of a plurality of UE capability parameters. The plurality of UE capability parameters may include one or more mandatory features, one or more constraints imposed on the one or more mandatory features, one or more default radio settings, or any combination thereof.

[0069] The term "UE capability set" may be replaced with other terms, such as, but not limited to, a feature set, a UE feature set, a category, a feature category, a UE category, a UE feature category, a UE capability group, a UE feature group, a UE capability class, a UE feature class, a UE capability pattern, a UE feature pattern, etc.

[0070] The multiple UE capability sets may be predefined in a (future) 3GPP specification. The association of each UE capability set with at least one use case and / or at least one device type may be defined in the (future) 3GPP specification. Specifically, the 3GPP specification may define multiple use cases, multiple device types, and multiple UE capability sets. The definition of the multiple UE capability sets specifies the association of each UE capability set with at least one predefined use case and / or at least one predefined device type. In addition, the definition of the multiple UE capability sets specifies the respective values ​​of multiple UE capability parameters included in each UE capability set.

[0071] Each UE capability set predefined in the 3GPP specifications may include any combination of general parameters, SDAP parameters, PDCP parameters, RLC parameters, MAC parameters, and measurement parameters. The general parameters may include parameters indicating whether the UE supports various functions (e.g., Radio Resource Control (RRC) inactive state, Signaling Radio Bearer 3 (SRB3), and Mobile-terminated Small Data Transmission (MT-SDT)). Additionally or alternatively, one or more of the UE capability sets predefined in the 3GPP specifications may include parameters associated with a specific UE device type. For example, a UE capability set may define values ​​of radio access capability parameters associated with a specific UE device type. A UE capability set may define values ​​indicating that one or more functions for a specific UE device type must be supported by the UE. Additionally or alternatively, one or more of the UE capability sets predefined in the 3GPP specifications may include parameters associated with a specific use case. For example, a UE capability set may define values ​​of radio access capability parameters associated with a specific use case. A UE capability set may define values ​​that indicate one or more features related to a particular use case that need to be supported by the UE.

[0072] A combination of UE capability parameters whose values ​​are defined by one of the predefined UE capability sets (e.g., a first UE capability set) may differ from a combination of UE capability parameters whose values ​​are defined by another of the predefined UE capability sets. For example, at least one of the UE capability parameters whose values ​​are defined by a first UE capability set may not be included in a plurality of UE capability parameters whose values ​​are defined by a second UE capability set different from the first UE capability set. A UE capability set defined in association with a specific use case may include at least one capability parameter that is different from any of the capability parameters included in other UE capability sets defined in association with other specific use cases. A UE capability set defined in association with a specific device type may include at least one capability parameter that is different from any of the capability parameters included in other UE capability sets defined in association with other specific device types.

[0073] The UE1 may further determine whether to include a PDCP sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. In other words, the UE1 may determine whether to use or omit a PDCP sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. The UE1 may determine whether to include a PDCP sublayer in Layer 2 according to at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. The UE1 may determine whether to include a PDCP sublayer in Layer 2 for each DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. That is, whether the UE1 uses a PDCP sublayer in a user plane protocol stack in the radio interface between the UE1 and the RAN2 may depend on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type.

[0074] In addition to or instead of the UE 1, the RAN node 3 performs operations similar to those of the UE 1 described above with reference to FIG. 3. The RAN node 3 provides, establishes, or configures a Layer 2 according to a specific RAT (e.g., 6G RAT) to transmit or receive PDUs of the PDU layer to or from the UE 1 via a PHY layer according to the specific RAT. The RAN node 3 determines whether to include an RLC sublayer in the Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. In other words, the RAN node 3 determines whether to use or omit the RLC sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. Whether the RAN node 3 uses the RLC sublayer in the user plane protocol stack in the air interface between the UE 1 and the RAN node 3 may depend on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type.

[0075] When the RAN node 3 makes the above-mentioned Layer 2-related decision, the RAN node 3 may generate a Layer 2 configuration based on the decision and transmit the generated Layer 2 configuration to the UE 1, for example, via an RRC message (e.g., an RRC Reconfiguration message). The UE 1 may provision, establish, or configure its own Layer 2 according to the received Layer 2 configuration. In this case, the UE 1 may not need to make the Layer 2-related decision shown in step 301 of FIG. 3 .

[0076] The RAN node 3 may determine whether to include an RLC sublayer in Layer 2 for each of multiple QoS flows belonging to the same PDU session. In this case, whether the RAN node 3 uses the RLC sublayer in the user plane protocol stack in the radio interface between the UE 1 and the RAN 2 may differ for each of multiple QoS flows belonging to the same PDU session. This control or concept can also be applied to multiple QoS flows belonging to different PDU sessions. In other words, whether the RAN node 3 uses the RLC sublayer may differ for each of multiple QoS flows belonging to different PDU sessions.

[0077] The RAN node 3 may determine whether to include the RLC sublayer in Layer 2 for each of multiple DRBs associated with the same PDU session. Therefore, whether the RAN node 3 uses the RLC sublayer in the user plane protocol stack in the radio interface between the UE 1 and the RAN 2 may differ for each of multiple DRBs associated with the same PDU session. This control or concept is also applicable to multiple DRBs associated with different PDU sessions. That is, whether the RAN node 3 uses the RLC sublayer may differ for each of multiple DRBs associated with different PDU sessions.

[0078] The RAN node 3 may determine for each network slice (e.g., S-NSSAI, NSAG) whether to include the RLC sublayer in Layer 2. Therefore, whether the RAN node 3 uses the RLC sublayer in the user plane protocol stack in the radio interface between the UE 1 and the RAN 2 may differ for each network slice.

[0079] The RAN node 3 may decide for each PDU session whether to include the RLC sublayer in Layer 2. Therefore, whether the RAN node 3 uses the RLC sublayer in the user plane protocol stack in the air interface between the UE 1 and the RAN 2 may vary for each PDU session.

[0080] The RAN node 3 may determine whether to include an RLC sublayer in Layer 2 based at least on an intended use case of the PDU layer PDUs transmitted by or by the UE 1. The RAN node 3 may receive from the UE 1 an identification (e.g., an identification, identifier, or index) of the use case intended by the UE 1 or the PDU layer PDUs. The RAN node 3 may determine whether to include an RLC sublayer in Layer 2 based at least on the received identification. The RAN node 3 may receive the identification of the use case from the core network 4 rather than from the UE 1.

[0081] The RAN node 3 may determine whether to include an RLC sublayer in Layer 2 based at least on the device type of the UE 1. The RAN node 3 may receive an identification (e.g., identity, identifier, or index) of the device type of the UE 1 from the UE 1. The RAN node 3 may determine whether to include an RLC sublayer in Layer 2 based at least on the received identification. The RAN node 3 may receive the device type identification from the core network 4 rather than from the UE 1.

[0082] The RAN node 3 may determine whether to include the RLC sublayer in Layer 2 based at least on the UE capability set or on an identification (e.g., identity, identifier, or index) of the UE capability set. The RAN node 3 may receive the identification of the UE capability set from the UE 1 or the core network 4.

[0083] The RAN node 3 may further determine whether to include a PDCP sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. In other words, the RAN node 3 may determine whether to use or omit a PDCP sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. Whether the RAN node 3 uses a PDCP sublayer in a user plane protocol stack in the radio interface between the UE 1 and the RAN node 3 may depend on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type.

[0084] Figure 4 shows an example of Layer 2 adaptation depending on the DRB, QoS flow, network slice, or PDU session. In the example of Figure 4, UE1 and RAN node 3 apply different Layer 2 processing to DRB #1, DRB #2, and DRB #3 associated with the same PDU session. Specifically, UE1 and RAN node 3 perform four L2 sublayer processing, i.e., SDAP, PDCP, RLC, and MAC sublayer processing, for PDU layer PDUs associated with (or mapped to) DRB #1. UE1 and RAN node 3 perform three L2 sublayer processing, i.e., SDAP, PDCP, and MAC sublayer processing, for PDU layer PDUs associated with DRB #2. UE1 and RAN node 3 perform two L2 sublayer processing, i.e., SDAP and MAC sublayer processing, for PDU layer PDUs associated with DRB #3.

[0085] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to QoS Flow #1, QoS Flow #2, and QoS Flow #3 that belong to the same PDU session. Specifically, UE1 and RAN node 3 process PDU layer PDUs belonging to QoS Flow #1 at four L2 sublayers, i.e., SDAP, PDCP, RLC, and MAC sublayers. UE1 and RAN node 3 process PDU layer PDUs belonging to QoS Flow #2 at three L2 sublayers, i.e., SDAP, PDCP, and MAC sublayers. UE1 and RAN node 3 process PDU layer PDUs belonging to QoS Flow #3 at two L2 sublayers, i.e., SDAP and MAC sublayers.

[0086] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to different network slices #1, #2, and #3. Specifically, UE1 and RAN node 3 process four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers, for PDU layer PDUs associated with network slice #1. UE1 and RAN node 3 process three L2 sublayers, namely, SDAP, PDCP, and MAC sublayers, for PDU layer PDUs associated with network slice #2. UE1 and RAN node 3 process two L2 sublayers, namely, SDAP and MAC sublayers, for PDU layer PDUs associated with network slice #3.

[0087] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to the different PDU session #1, PDU session #2, and PDU session #3. Specifically, UE1 and RAN node 3 process PDU layer PDUs belonging to PDU session #1 at four L2 sublayers, i.e., SDAP, PDCP, RLC, and MAC sublayers. UE1 and RAN node 3 process PDU layer PDUs belonging to PDU session #2 at three L2 sublayers, i.e., SDAP, PDCP, and MAC sublayers. UE1 and RAN node 3 process PDU layer PDUs belonging to PDU session #3 at two L2 sublayers, i.e., SDAP and MAC sublayers.

[0088] Figure 5 shows an example of Layer 2 adaptation depending on the use case. In the example of Figure 5, UE1 and RAN node 3 apply different Layer 2 processing to different use cases intended by UE1 or by the PDU layer PDUs of UE1. Specifically, UE1 and RAN node 3 process four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers, for PDU layer PDUs related to eMBB services or immersive (or XR) services. UE1 and RAN node 3 process three L2 sublayers, namely, SDAP, PDCP, and MAC sublayers, for PDU layer PDUs related to IoT services. UE1 and RAN node 3 process two L2 sublayers, namely, SDAP and MAC sublayers, for PDU layer PDUs related to URLLC services.

[0089] Figure 6 shows an example of Layer 2 adaptation depending on device type. In the example of Figure 6, UE1 and RAN node 3 apply different Layer 2 processing to different device types. Specifically, if UE1 is a handheld device or a wearable device, UE1 and RAN node 3 process the PDU layer PDUs of UE1 at four L2 sublayers, i.e., SDAP, PDCP, RLC, and MAC sublayers. If UE1 is a sensor device, UE1 and RAN node 3 process the PDU layer PDUs of UE1 at three L2 sublayers, i.e., SDAP, PDCP, and MAC sublayers. If UE1 is a robotics device, UE1 and RAN node 3 process the PDU layer PDUs of UE1 at two L2 sublayers, i.e., SDAP and MAC sublayers.

[0090] The layer 2 architecture or protocol stack adaptation described in this embodiment may be applied independently to the UL and DL. For example, the UE 1 and the RAN node 3 may apply the layer 2 architecture or protocol stack adaptation only to the UL. Alternatively, the UE 1 and the RAN node 3 may apply the layer 2 architecture or protocol stack adaptation only to the DL. Alternatively, the UE 1 and the RAN node 3 may apply different adaptations to the UL and DL.

[0091] According to the operations of the UE 1 and the RAN node 3 described in this embodiment, one or both of the UE 1 and the RAN node 3 determine whether to include an RLC sublayer in Layer 2 based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. This therefore enables flexible modification or adaptation of the Layer 2 structure or protocol stack of the radio interface between the UE 1 and the RAN 2. For example, this allows the L2 sublayer configuration for communications (e.g., data transmission or reception, control signal transmission or reception) or services terminated between the UE 1 itself and the network (e.g., the RAN node 3) to be different from the usual configuration when the UE 1 is a specific device type or is intended for a specific use case.

[0092] Second Embodiment This embodiment provides an example of adaptation of the Layer 2 structure or protocol stack of the radio interface between the UE 1 and the RAN node 3. Figure 7 shows an example of the operation of the UE 1.

[0093] In step 701, UE1 determines whether to use a first number of sublayers in Layer 2 or a second number of sublayers less than the first number in Layer 2 based on at least one of DRB, QoS flow, network slice, PDU session, use case, or device type. When using the second number of sublayers in Layer 2, UE1 transfers or merges (integrates, or consolidates) at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers. This Layer 2 is a Layer 2 related to a specific RAT (e.g., 6G RAT) and is used to transmit PDUs of the PDU layer to or receive PDUs from RAN2 via a PHY layer according to the specific RAT.

[0094] In step 702, UE1 provisions Layer 2 according to a specific RAT according to the determination in step 701. Provisioning Layer 2 may also be referred to as establishing Layer 2 or configuring Layer 2.

[0095] The first number of sublayers may include at least a PDCP, an RLC, and a MAC sublayer. The first number of sublayers may include four sublayers: an SDAP, a PDCP, an RLC, and a MAC sublayer. In contrast, the second number of sublayers may include a modified (enhanced, or improved) PDCP sublayer and a modified MAC sublayer by integrating the retransmission function of RLC SDUs in the RLC sublayer into the PDCP sublayer and the segmentation function of RLC SDUs in the RLC sublayer into the MAC sublayer. In other words, the second number of sublayers may not include an RLC sublayer. The second number of sublayers may include three sublayers: an SDAP, a (modified) PDCP, and a (modified) MAC sublayer.

[0096] The use case may be one of a number of predefined use cases, which may be predefined in a (future) 3GPP specification, and may include one or any combination of eMBB, URLLC, immersive (or XR), NTN, IoT, UAV, and V2X.

[0097] The device type may be one of a number of predefined device types, which may be predefined in (future) 3GPP specifications, including one or any combination of a handheld device, a robotics device, a wearable device, a sensor device, and an automotive device.

[0098] UE1 may determine whether to use the first or second number of L2 sublayers for each of multiple QoS flows belonging to the same PDU session. In this case, whether UE1 uses the first or second number of L2 sublayers may differ for each of multiple QoS flows belonging to the same PDU session. This control or concept can also be applied to multiple QoS flows belonging to different PDU sessions. In other words, whether UE1 uses the first or second number of L2 sublayers may differ for each of multiple QoS flows belonging to different PDU sessions.

[0099] UE1 may determine whether to use the first or second number of L2 sublayers for each of multiple DRBs associated with the same PDU session. Therefore, whether UE1 uses the first or second number of L2 sublayers may differ for each of multiple DRBs associated with the same PDU session. This control or concept is also applicable to multiple DRBs associated with different PDU sessions. That is, whether UE1 uses the first or second number of L2 sublayers may differ for each of multiple DRBs associated with different PDU sessions.

[0100] UE1 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers for each network slice (e.g., S-NSSAI, NSAG). Therefore, whether UE1 uses the first number of L2 sublayers or the second number of L2 sublayers may differ for each network slice.

[0101] UE1 may determine whether to use the first or second number of L2 sublayers for each PDU session, and therefore, whether UE1 uses the first or second number of L2 sublayers may differ for each PDU session.

[0102] The UE1 may determine whether to use the first or second number of L2 sublayers based at least on an intended use case of the transmitted PDU layer PDUs. The UE1 may determine whether to use the first or second number of L2 sublayers based at least in accordance with configuration information generated by the RAN2 (e.g., RAN node 3) based on the intended use case of the transmitted PDU layer PDUs. The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration.

[0103] The UE 1 may determine whether to use the first or second number of L2 sublayers based at least on a device type of the UE 1. The UE 1 may determine whether to use the first or second number of L2 sublayers based at least in accordance with configuration information generated by the RAN 2 (e.g., RAN node 3) based on the device type of the UE 1. The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration.

[0104] UE1 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers based at least on the UE capability set or at least on an identification (e.g., identification information, identifier, or index) of the UE capability set. UE1 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers based at least on the UE capability set of UE1 according to configuration information generated by RAN2 (e.g., RAN node 3). The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration. The definition of the UE capability set in this embodiment is the same as that described in the first embodiment.

[0105] In addition to or instead of the UE 1, the RAN node 3 performs operations similar to those of the UE 1 described above with reference to Figure 7. The RAN node 3 provides, establishes, or configures a Layer 2 according to a specific RAT (e.g., 6G RAT) to transmit or receive PDUs of the PDU layer to or from the UE 1 via a PHY layer according to the RAT. The RAN node 3 determines whether to use a first number of L2 sublayers or a second number of L2 sublayers based on at least one of DRB, QoS flow, network slice, PDU session, use case, or device type. When using the second number of sublayers in Layer 2, the RAN node 3 transfers or merges, integrates, or consolidates at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers.

[0106] When the RAN node 3 makes the above-mentioned Layer 2-related decision, the RAN node 3 may generate a Layer 2 configuration based on the decision and send the generated Layer 2 configuration to the UE 1, for example, via an RRC message (e.g., an RRC Reconfiguration message). The UE 1 may provision, establish, or configure its own Layer 2 according to the received Layer 2 configuration. In this case, the UE 1 may not need to make the Layer 2-related decision shown in step 701 of FIG. 7.

[0107] The RAN node 3 may determine whether to use the first or second number of L2 sublayers for each of multiple QoS flows belonging to the same PDU session. In this case, whether the RAN node 3 uses the first or second number of L2 sublayers may differ for each of multiple QoS flows belonging to the same PDU session. This control or concept can also be applied to multiple QoS flows belonging to different PDU sessions. In other words, whether the RAN node 3 uses the first or second number of L2 sublayers may differ for each of multiple QoS flows belonging to different PDU sessions.

[0108] The RAN node 3 may determine whether to use the first or second number of L2 sublayers for each of multiple DRBs associated with the same PDU session. Therefore, whether the RAN node 3 uses the first or second number of L2 sublayers may differ for each of multiple DRBs associated with the same PDU session. This control or concept is also applicable to multiple DRBs associated with different PDU sessions. That is, whether the RAN node 3 uses the first or second number of L2 sublayers may differ for each of multiple DRBs associated with different PDU sessions.

[0109] The RAN node 3 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers for each network slice (e.g., S-NSSAI, NSAG). Therefore, whether the RAN node 3 uses the first number of L2 sublayers or the second number of L2 sublayers may differ for each network slice.

[0110] The RAN node 3 may determine for each PDU session whether to use the first or second number of L2 sublayers, and therefore whether the RAN node 3 uses the first or second number of L2 sublayers may differ for each PDU session.

[0111] The RAN node 3 may determine whether to use the first or second number of L2 sublayers based at least on an intended use case of the PDU layer PDUs transmitted by or by the UE 1. The RAN node 3 may receive from the UE 1 an identification (e.g., an identification, identifier, or index) of the use case intended by the UE 1 or the PDU layer PDUs. The RAN node 3 may determine whether to use the first or second number of L2 sublayers based at least on the received identification. The RAN node 3 may receive the identification of the use case from the core network 4 rather than from the UE 1.

[0112] The RAN node 3 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers based at least on the device type of the UE 1. The RAN node 3 may receive an identification (e.g., identity information, identifier, or index) of the device type of the UE 1 from the UE 1. The RAN node 3 may determine whether to use the first number of L2 sublayers or the second number of L2 sublayers based at least on the received identification. The RAN node 3 may receive the device type identification from the core network 4 rather than from the UE 1.

[0113] The RAN node 3 may determine whether to use the first or second number of L2 sublayers based at least on the UE capability set or on an identification (e.g., identification information, identifier, or index) of the UE capability set. The RAN node 3 may receive the identification of the UE capability set from the UE 1 or the core network 4.

[0114] Figure 8 illustrates an example of Layer 2 adaptation depending on the DRB, QoS flow, network slice, or PDU session. In the example of Figure 8, UE1 and RAN node 3 apply different Layer 2 processing to DRB #1 and DRB #2 associated with the same PDU session. Specifically, UE1 and RAN node 3 process PDU layer PDUs associated with (or mapped to) DRB #1 through four L2 sublayers: SDAP, PDCP, RLC, and MAC. The RLC sublayer includes retransmission and segmentation functions. Meanwhile, UE1 and RAN node 3 process PDU layer PDUs associated with DRB #2 through three L2 sublayers: SDAP, modified PDCP, and modified MAC. The modified PDCP sublayer merges, integrates, or consolidates the retransmission function of the omitted RLC sublayer. The modified MAC sublayer merges, integrates, or consolidates the segmentation functionality of the omitted RLC sublayer.

[0115] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to QoS flow #1 and QoS flow #2 belonging to the same PDU session. Specifically, UE1 and RAN node 3 process PDU layer PDUs belonging to QoS flow #1 at four L2 sublayers, i.e., SDAP, PDCP, RLC, and MAC sublayers. UE1 and RAN node 3 process PDU layer PDUs belonging to QoS flow #2 at three L2 sublayers, i.e., SDAP, modified PDCP, and modified MAC sublayers.

[0116] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to different network slices #1 and #2. Specifically, UE1 and RAN node 3 perform processing of four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers, for PDU layer PDUs associated with network slice #1. UE1 and RAN node 3 perform processing of three L2 sublayers, namely, SDAP, modified PDCP, and modified MAC sublayers, for PDU layer PDUs associated with network slice #2.

[0117] Alternatively, UE1 and RAN node 3 apply different Layer 2 processing to the different PDU session #1 and PDU session #2. Specifically, UE1 and RAN node 3 perform processing at four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers, on PDU layer PDUs belonging to PDU session #1. UE1 and RAN node 3 perform processing at three L2 sublayers, namely, SDAP, modified PDCP, and modified MAC sublayers, on PDU layer PDUs belonging to PDU session #2.

[0118] Figure 9 shows an example of Layer 2 adaptation depending on the use case. In the example of Figure 9, UE1 and RAN node 3 apply different Layer 2 processing to different use cases intended by UE1 or by the PDU layer PDUs of UE1. Specifically, UE1 and RAN node 3 process four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers, for PDU layer PDUs related to eMBB services or immersive (or XR) services. The RLC sublayer includes retransmission and segmentation functions. Meanwhile, UE1 and RAN node 3 process three L2 sublayers, namely, SDAP, modified PDCP, and modified MAC sublayers, for PDU layer PDUs related to IoT services.

[0119] Figure 10 shows an example of Layer 2 adaptation depending on device type. In the example of Figure 6, UE1 and RAN node 3 apply different Layer 2 processing to different device types. Specifically, if UE1 is a handheld device or a wearable device, UE1 and RAN node 3 process the PDU layer PDUs of UE1 at four L2 sublayers, namely, SDAP, PDCP, RLC, and MAC sublayers. The RLC sublayer includes retransmission and segmentation functions. On the other hand, if UE1 is a sensor device, UE1 and RAN node 3 process the PDU layer PDUs of UE1 at three L2 sublayers, namely, SDAP, modified PDCP, and modified MAC sublayers.

[0120] According to the operation of the UE 1 and the RAN node 3 described in this embodiment, one or both of the UE 1 and the RAN node 3 determine whether to use a first number of L2 sublayers or a second number of L2 sublayers based on at least one of a DRB, a QoS flow, a network slice, a PDU session, a use case, or a device type. This therefore enables flexible modification or adaptation of the Layer 2 structure or protocol stack of the air interface between the UE 1 and the RAN 2. For example, this may allow the L2 sublayer configuration for communications (e.g., data transmission or reception, control signal transmission or reception) or services terminated between the UE 1 itself and the network (e.g., the RAN node 3) to be different from the usual configuration when the UE 1 is a specific device type or is intended for a specific use case.

[0121] Third Embodiment This embodiment provides an example of adaptation of the Layer 2 structure or protocol stack of the radio interface between a UE 1 and a RAN node 3. Fig. 11 shows an example of the operation of a UE 1. In step 1101, the UE 1 determines whether to enable or disable at least one function in at least one sublayer included in Layer 2 based on one or both of a use case and a device type. This Layer 2 is a Layer 2 related to a specific RAT (e.g., 6G RAT) and is used to transmit PDUs of the PDU layer to or receive PDUs from the RAN 2 via a PHY layer according to the specific RAT.

[0122] In step 1102, UE1 provisions Layer 2 according to a specific RAT according to the determination in step 1101. Provisioning Layer 2 may also be referred to as establishing Layer 2 or configuring Layer 2.

[0123] The UE1 may determine whether to enable or disable at least one function in at least one sublayer included in Layer 2 depending on one or both of a use case and a device type. The UE1 may determine whether to enable or disable at least one function in at least one sublayer included in Layer 2 for each use case or device type. That is, whether the UE1 disables a specific L2 function in a user plane protocol stack in the air interface between the UE1 and the RAN2 may depend on one or both of a use case and a device type.

[0124] The use case may be one of a number of predefined use cases, which may be predefined in a (future) 3GPP specification, and may include one or any combination of eMBB, URLLC, immersive (or XR), NTN, IoT, UAV, and V2X.

[0125] The device type may be one of a number of predefined device types, which may be predefined in (future) 3GPP specifications, including one or any combination of a handheld device, a robotics device, a wearable device, a sensor device, and an automotive device.

[0126] The at least one L2 function that may be disabled by UE1 may include segmentation of RLC SDUs in AM data transfer, performed in the RLC sublayer. Additionally or alternatively, the at least one L2 function that may be disabled by UE1 may include integrity protection and integrity verification, performed in the PDCP sublayer.

[0127] The UE 1 may determine whether to disable at least one L2 feature based at least on an intended use case of the transmitted PDU layer PDUs. The UE 1 may determine whether to disable at least one L2 feature at least in accordance with configuration information generated by the RAN 2 (e.g., RAN node 3) based on the intended use case of the transmitted PDU layer PDUs. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration.

[0128] The UE 1 may determine whether to disable at least one L2 feature based at least on a device type of the UE 1. The UE 1 may determine whether to disable at least one L2 feature at least in accordance with configuration information generated by the RAN 2 (e.g., RAN node 3) based on the device type of the UE 1. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration.

[0129] The UE1 may determine whether to disable at least one L2 feature based at least on the UE capability set or at least on an identification (e.g., identification information, identifier, or index) of the UE capability set. The UE1 may determine whether to disable at least one L2 feature at least according to configuration information generated by the RAN2 (e.g., RAN node 3) based on the UE capability set of the UE1. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration. The definition of the UE capability set in this embodiment is the same as that described in the first embodiment.

[0130] In addition to or instead of the UE 1, the RAN node 3 performs operations similar to those of the UE 1 described above with reference to Figure 11. The RAN node 3 provides, establishes, or configures a Layer 2 according to a specific RAT (e.g., 6G RAT) to transmit PDUs of the PDU layer to or receive PDUs from the UE 1 via a PHY layer according to the specific RAT. The RAN node 3 determines whether to enable or disable at least one function in at least one sublayer included in the Layer 2 based on one or both of a use case and a device type.

[0131] When the RAN node 3 makes the above-mentioned Layer 2-related decision, the RAN node 3 may generate a Layer 2 configuration based on the decision and transmit the generated Layer 2 configuration to the UE 1, for example, via an RRC message (e.g., an RRC Reconfiguration message). The UE 1 may provision, establish, or configure its own Layer 2 according to the received Layer 2 configuration. In this case, the UE 1 may not need to make the Layer 2-related decision shown in step 1101 of FIG. 11 .

[0132] The RAN node 3 may determine whether to enable or disable at least one function in at least one sublayer included in Layer 2 depending on either or both of a use case and a device type. The RAN node 3 may determine whether to enable or disable at least one function in at least one sublayer included in Layer 2 for each use case or device type. Whether the RAN node 3 disables a particular L2 function in a user plane protocol stack in the air interface between the UE 1 and the RAN node 3 may depend on either or both of a use case and a device type.

[0133] The RAN node 3 may determine whether to disable at least one L2 feature based at least on an intended use case of the PDU layer PDUs transmitted by or by the UE 1. The RAN node 3 may receive from the UE 1 an identification (e.g., an identification, an identifier, or an index) of the use case intended by the UE 1 or the PDU layer PDUs. The RAN node 3 may determine whether to disable at least one L2 feature based at least on the received identification. The RAN node 3 may receive the identification of the use case from the core network 4 rather than from the UE 1.

[0134] The RAN node 3 may determine whether to disable at least one L2 function based at least on the device type of the UE 1. The RAN node 3 may receive an identification (e.g., identity information, identifier, or index) of the device type of the UE 1 from the UE 1. The RAN node 3 may determine whether to disable at least one L2 function based at least on the received identification. The RAN node 3 may receive the device type identification from the core network 4 rather than from the UE 1.

[0135] The RAN node 3 may determine whether to disable at least one L2 feature based at least on the UE capability set or based at least on an identification (e.g., identity, identifier, or index) of the UE capability set. The RAN node 3 may receive the identification of the UE capability set from the UE 1 or the core network 4.

[0136] The layer 2 architecture or protocol stack adaptation described in this embodiment may be applied independently to the UL and DL. For example, the UE 1 and the RAN node 3 may apply the layer 2 architecture or protocol stack adaptation only to the UL. Alternatively, the UE 1 and the RAN node 3 may apply the layer 2 architecture or protocol stack adaptation only to the DL. Alternatively, the UE 1 and the RAN node 3 may apply different adaptations to the UL and DL.

[0137] According to the operation of the UE 1 and the RAN node 3 described in this embodiment, one or both of the UE 1 and the RAN node 3 determine whether to disable at least one L2 function based on one or both of a use case and a device type. This therefore enables flexible modification or adaptation of the Layer 2 structure or protocol stack of the air interface between the UE 1 and the RAN 2. For example, this allows the L2 sublayer configuration for communications (e.g., data transmission or reception, control signal transmission or reception) or services terminated between the UE 1 itself and the network (e.g., the RAN node 3) to be different from the usual configuration when the UE 1 is a specific device type or is intended for a specific use case.

[0138] <Fourth embodiment> This embodiment provides an example of adaptation of the Layer 2 structure or protocol stack of the radio interface between the UE 1 and the RAN node 3. Figure 12 shows an example of the operation of the UE 1.

[0139] In step 1202, UE1 selects functions to be used in Layer 2 from a set of predefined Layer 2 functions based on one or both of a use case and a device type. UE1 configures Layer 2 by assigning the selected functions to two or more sublayers within Layer 2. This Layer 2 is related to a specific Radio Access Technology (RAT) (e.g., 6G RAT) and is used to transmit PDUs of the PDU layer to and receive PDUs from RAN2 via a PHY layer according to the specific RAT.

[0140] In step 1202, UE1 provisions Layer 2 according to a specific RAT according to the selection in step 1201. Provisioning Layer 2 may also be referred to as establishing Layer 2 or configuring Layer 2.

[0141] The use case may be one of a number of predefined use cases, which may be predefined in a (future) 3GPP specification, and may include one or any combination of eMBB, URLLC, immersive (or XR), NTN, IoT, UAV, and V2X.

[0142] The device type may be one of a number of predefined device types, which may be predefined in (future) 3GPP specifications, including one or any combination of a handheld device, a robotics device, a wearable device, a sensor device, and an automotive device.

[0143] The predefined Layer 2 feature set may include any combination of header compression, integrity protection of SDUs, ciphering, segmentation of SDUs, AM data transfer, UM data transfer, logical channel prioritization, multiplexing of SDUs, error correction with HARQ, and random access procedures. Alternatively, the predefined Layer 2 feature set may include some or all of the major services and functions of the PDCP, RLC, and MAC sublayers described above.

[0144] The UE 1 may select the functions to be used at Layer 2 based at least on an intended use case of the transmitted PDU layer PDUs. The UE 1 may select the functions to be used at Layer 2 at least in accordance with configuration information generated by the RAN 2 (e.g., RAN node 3) based on the intended use case of the transmitted PDU layer PDUs. The configuration information may be an RRC configuration or Layer 2-related configuration included in the RRC configuration.

[0145] The UE 1 may select a plurality of functions to be used in Layer 2 based at least on a device type of the UE 1. The UE 1 may select a plurality of functions to be used in Layer 2 at least in accordance with configuration information generated by the RAN 2 (e.g., RAN node 3) based on the device type of the UE 1. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration.

[0146] UE1 may select a plurality of functions to be used in Layer 2 based at least on the UE capability set or at least on an identification (e.g., identification information, identifier, or index) of the UE capability set. UE1 may select a plurality of functions to be used in Layer 2 at least according to configuration information generated by RAN2 (e.g., RAN node 3) based on the UE capability set of UE1. The configuration information may be an RRC configuration or a Layer 2-related configuration included in the RRC configuration. The definition of the UE capability set in this embodiment is the same as that described in the first embodiment.

[0147] In addition to or instead of UE1, RAN node 3 performs operations similar to those of UE1 described above with reference to Figure 12. RAN node 3 provides, establishes, or configures Layer 2 according to a particular RAT (e.g., 6G RAT) to transmit PDUs of the PDU layer to UE1 or receive them from RAN 2 via a PHY layer according to the particular RAT. RAN node 3 selects multiple functions to be used in Layer 2 based on one or both of a use case and a device type.

[0148] When the RAN node 3 makes the above-mentioned Layer 2-related decision, the RAN node 3 may generate a Layer 2 configuration based on the decision and transmit the generated Layer 2 configuration to the UE 1, for example, via an RRC message (e.g., an RRC Reconfiguration message). The UE 1 may provision, establish, or configure its own Layer 2 according to the received Layer 2 configuration. In this case, the UE 1 may not need to make the Layer 2-related decision shown in step 1201 of FIG. 12 .

[0149] The RAN node 3 may select functions to be used in Layer 2 depending on either or both of the use case and the device type. The RAN node 3 may determine functions to be used in Layer 2 for each use case or device type. The subset of Layer 2 functions that the RAN node 3 uses in the user plane protocol stack in the air interface between the UE 1 and the RAN node 3 may differ depending on either or both of the use case and the device type.

[0150] The RAN node 3 may select functions to be used at Layer 2 based at least on an intended use case of the PDU layer PDUs to be transmitted or by the UE 1. The RAN node 3 may receive from the UE 1 an identification (e.g., an identification, identifier, or index) of the use case intended by the UE 1 or the PDU layer PDUs. The RAN node 3 may select functions to be used at Layer 2 based at least on the received identification. The RAN node 3 may receive the identification of the use case from the core network 4 rather than from the UE 1.

[0151] The RAN node 3 may select a plurality of functions to be used in Layer 2 based at least on the device type of the UE 1. The RAN node 3 may receive an identification (e.g., identity, identifier, or index) of the device type of the UE 1 from the UE 1. The RAN node 3 may select a plurality of functions to be used in Layer 2 based at least on the received identification. The RAN node 3 may receive the device type identification from the core network 4 rather than from the UE 1.

[0152] The RAN node 3 may select a number of functions to be used at Layer 2 based at least on the UE capability set or based at least on an identification (e.g., identity, identifier, or index) of the UE capability set. The RAN node 3 may receive the identification of the UE capability set from the UE 1 or the core network 4.

[0153] Figure 13 shows an example of Layer 2 adaptation depending on use case and / or device type. In the example of Figure 13, UE1 and RAN node 3 select different subsets of functions from a predefined set of Layer 2 functions for different use cases intended by UE1 or by PDU layer PDUs of UE1. Additionally or alternatively, UE1 and RAN node 3 select different subsets of functions from a predefined set of Layer 2 functions for different device types.

[0154] Specifically, if UE1 is intended for use case #1, if UE1 is device type #1, or both, UE1 and RAN node 3 use an upper L2 sublayer and a lower L2 sublayer. The upper L2 sublayer includes ciphering, integrity protection and verification, and UM data transfer, selected from a predefined set of features. The lower L2 sublayer includes error correction with HARQ and random access procedures, selected from a predefined set of features.

[0155] On the other hand, if UE1 is intended for use case #2, or is device type #2, or both, UE1 and RAN node 3 use upper, middle, and lower L2 sublayers. The upper L2 sublayer includes encryption and integrity protection and verification selected from a predefined set of functions. The middle L2 sublayer includes segmentation of SDUs and AM data transfer selected from a predefined set of functions. The lower L2 sublayer includes logical channel prioritization, multiplexing and demultiplexing of SDUs, error correction with HARQ, and random access procedures selected from a predefined set of functions.

[0156] According to the operation of the UE 1 and the RAN node 3 described in this embodiment, one or both of the UE 1 and the RAN node 3 selects multiple functions to be used in Layer 2 from a predefined set of Layer 2 functions based on one or both of a use case and a device type. This therefore enables flexible modification or adaptation of the Layer 2 structure or protocol stack of the air interface between the UE 1 and the RAN 2. For example, this allows the L2 sublayer configuration for communications (e.g., data transmission or reception, control signal transmission or reception) or services terminated between the UE 1 itself and the network (e.g., RAN node 3) to be different from the usual one when the UE 1 is a specific device type or is intended for a specific use case.

[0157] Fifth Embodiment In this embodiment, the UE1 sets up Layer 2 (or AS layer) based on a service (or use case) requested or triggered from an upper layer (e.g., application layer or PDU layer). Specifically, the UE1 determines an access category or an access identity, or both, corresponding to the requested or triggered service (or use case), and sets up Layer 2 (or AS layer) based on the determined access category or access identity, or both.

[0158] Figure 14 shows an example of the operation of the UE 1 and the RAN node 3. In step 1401, the NAS layer 11 of the UE 1 is triggered or requested for a service from a higher layer (eg, application layer or PDU layer).

[0159] In step 1402, the UE NAS layer 11 determines or selects an access category or an access identity, or both, corresponding to the trigger or the requested service. The definitions of the access category and the access identity may be similar to those of 5G NR. The UE NAS layer 11 sends or passes the determined access category or the access identity, or both, to the Access Stratum (AS) layer 12 of the UE 1. The UE AS layer 12 includes an RRC layer.

[0160] An access category and / or access identity is associated with a use case. The association between an access category and / or access identity and a use case may be defined in a (future) 3GPP specification. Alternatively, this association may be pre-configured in the UE 1 by the RAN node 3 or by the core network via the RAN node 3.

[0161] In step 1403, the UE AS layer 12 performs or initiates a layer 2 (L2) protocol setup based on the received access category and / or access identity. L2 protocol setup may also be referred to as AS layer protocol setup. L2 protocol setup includes setting up, establishing, configuring, or preparing the layer 2 (or AS layer) so that the layer 2 (or AS layer) is configured according to the access category and / or access identity (and associated use case).

[0162] The UE AS layer 12 may configure Layer 2 mandatory functionality (optionally with default settings) based on the received Access Category and / or Access Identity (and associated Use Case). The UE AS layer 12 may also configure Layer 2 default radio configuration (optionally with default values ​​for some parameters) based on the received Access Category and / or Access Identity (and associated Use Case).

[0163] Additionally or alternatively, the UE AS layer 12 may perform an adaptation of the Layer 2 structure or protocol stack. This L2 adaptation may be one or any combination of the various L2 adaptations described in the first to fourth embodiments. For example, this L2 adaptation may include one or any combination of the following four examples:

[0164] In a first example, based on the received access category and / or access identity (and associated use case), the UE AS Layer 12 determines or knows whether to include a particular sublayer in Layer 2 (e.g., a PDCP sublayer or an RLC sublayer or both).

[0165] In a second example, based on the received access category or access identity or both (and the associated use case), the UE AS layer 12 determines or recognizes whether to use a first number of sublayers in Layer 2 or a second number of sublayers, which is less than the first number, in Layer 2. The second number of sublayers may be realized by moving or integrating at least one function provided by one or more sublayers included in the first number of sublayers (e.g., RLC sublayer) into one or more other sublayers (e.g., PDCP sublayer or MAC sublayer, or both).

[0166] In a third example, based on the received access category or access identity or both (and the associated use case), the UE AS layer 12 determines or knows whether to enable or disable at least one feature in at least one sub-layer included in layer 2.

[0167] In a fourth example, based on the received access category and / or access identity (and associated use case), the UE AS layer 12 selects multiple functions to be used at layer 2 from a set of predefined layer 2 functions.

[0168] Through the coordinated operation of the UE NAS Layer 11 and the UE AS Layer 12 in steps 1402 and 1403, the UE 1 can set up Layer 2 (or AS layer) corresponding to the requested or triggered service.

[0169] The UE AS layer 12 communicates with the RAN node 3 for L2 protocol setup. The UE AS layer 12 may receive L2 layer configuration from the RAN node 3. By way of example, as shown in steps 1404-1406 of Figure 14, the UE AS layer 12 may set up, establish, configure, or prepare Layer 2 (or AS layer) through RRC connection setup (step 1404), receiving an RRC Reconfiguration message (step 1405), and sending an RRC Reconfiguration Complete message (step 1406).

[0170] Sixth Embodiment In this embodiment, UE1 sets up Layer 2 (or AS layer) based on a service requested or triggered from a higher layer (e.g., application layer or PDU layer). Specifically, UE1 determines a network slice or network slice identification information corresponding to the requested or triggered service (or use case), and sets up Layer 2 (or AS layer) based on the determined network slice or network slice identification information.

[0171] Figure 15 shows an example of the operation of the UE 1 and the RAN node 3. In step 1501, the NAS layer 11 of the UE 1 is triggered or requested for a service from a higher layer (eg, application layer or PDU layer).

[0172] In step 1502, the UE NAS layer 11 determines or selects a network slice or network slice identification information corresponding to the triggered or requested service. The UE NAS layer 11 sends or passes the determined network slice identification information to the AS layer 12 of the UE 1. The UE AS layer 12 includes an RRC layer.

[0173] The network slice or the network slice identity is associated with a use case. The association between the network slice or the network slice identity and the use case may be pre-configured in the UE 1 by the RAN node 3 or by the core network via the RAN node 3.

[0174] The network slice identity may be an S-NSSAI. Additionally or alternatively, the network slice identity may be an NSAG ID. The NSAG information is provided to the UE 1 from the core network at the NAS layer. The NSAG information includes a list of NSAGs, and for each NSAG, includes an NSAG ID, a list of S-NSSAI(s), and a priority value associated with the NSAG.

[0175] In step 1503, the UE AS layer 12 performs or initiates layer 2 (L2) protocol setup based on the received network slice identification information. The L2 protocol setup may be rephrased as AS layer protocol setup. The L2 protocol setup includes setting up, establishing, configuring, or preparing the layer 2 (or AS layer) so that the layer 2 (or AS layer) is configured according to the network slice identification information (and the associated use case). Examples of the L2 protocol setup are similar to those described with reference to FIG. 14 in the fifth embodiment.

[0176] Through the coordinated operation of the UE NAS layer 11 and the UE AS layer 12 in steps 1502 and 1503, the UE 1 can set up Layer 2 (or AS layer) corresponding to the requested or triggered service.

[0177] Steps 1504 to 1506 are similar to steps 1404 to 1506 in FIG.

[0178] Other Embodiment 1 Some PHY functions and MAC functions may be merged. Specifically, some PHY functions may be moved entirely to the MAC sublayer. Additionally or alternatively, some MAC functions may be moved entirely to the PHY layer.

[0179] Some PHY and MAC functions may be combined, specifically some PHY functions may be partially moved or integrated into the MAC sublayer, and additionally or alternatively some MAC functions may be partially moved or integrated into the PHY layer.

[0180] <Modification 2> An RLC mixed mode (e.g., mixed mode (MM), dynamic mode (DM), flexible mode (FM)) in which two or more of the three modes (e.g., AM, UM, TM) of the RLC sublayer are mixed may be defined. For example, when at least one of a certain use case and device type is applicable, the UE 1 and the RAN node 3 apply the RLC mixed mode. Specifically, the UE 1 and the RAN node 3 configure the RLC mixed mode for one DRB or QoS flow. For example, the UE 1 and the RAN node 3 may apply the RLC AM mode to some data (e.g., data packets, PDU data) of one DRB and the RLC UM mode to other data of the same DRB. For example, the UE 1 and the RAN node 3 may apply the RLC AM mode to some data (e.g., data packets, PDU data) of one QoS flow and the RLC UM mode to other data of the same QoS flow.

[0181] Additionally or alternatively, the UE 1 and the RAN node 3 may dynamically determine the RLC mode depending on at least one of the characteristics, type, and status of the data. Alternatively, at least one of the characteristics, type, and status of the data may be pre-associated with the corresponding RLC mode. The characteristics of the data may be, for example, real time or non-real time. The types of data may include, for example, higher priority and lower priority, and may also or alternatively include essential and non-essential. The status of the data may include, for example, delayed, not-delayed, and less time remaining in the delay budget.

[0182] The UE 1 may autonomously determine and switch the RLC mode, or the RAN node 3 may determine and instruct the UE 1 to switch the RLC mode. The instruction may be given, for example, by a downlink control signal (e.g., Physical Downlink Control Channel (PDCCH), MAC Control Element (CE), RRC message).

[0183] The RLC mixed mode may be applied independently to the UL and DL. For example, the UE 1 and the RAN node 3 may apply the RLC mixed mode only to the UL. Alternatively, the UE 1 and the RAN node 3 may apply the RLC mixed mode only to the DL. Alternatively, the UE 1 and the RAN node 3 may apply different RLC modes to the UL and DL.

[0184] When the RAN node 3 determines whether to switch the RLC mode, the RAN node 3 may make the determination by further considering the load status of the cell (e.g., congestion status, radio resource usage status). Additionally or alternatively, the RAN node 3 may further consider the cell quality at the UE 1 (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or Signal to Interference plus Noise Ratio (SINR)) when determining whether to switch the RLC mode.

[0185] These may be realized without introducing a new mode called RLC mixed mode. For example, multiple RLC modes may be configured for one DRB or QoS flow, and the UE 1 and the RAN node 3 may use the multiple RLC modes as described above.

[0186] Next, exemplary configurations of a UE 1 and a RAN node 3 related to the above-described embodiments will be described. FIG. 16 is a block diagram showing an exemplary configuration of a UE 1. An RF transceiver 1601 performs analog RF signal processing for communication with the RAN node 3. The RF transceiver 1601 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1601 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1601 is coupled to an antenna array 1602 and a baseband processor 1603. The RF transceiver 1601 receives modulation symbol data (or orthogonal frequency-division multiplexing (OFDM) symbol data) from the baseband processor 1603, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1602. The RF transceiver 1601 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1602 and provides the baseband receive signal to the baseband processor 1603. The RF transceiver 1601 may include an analog beamformer circuit for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0187] The baseband processor 1603 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing may include (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing may include communication management of Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0188] For example, the digital baseband signal processing by the baseband processor 1603 may include signal processing of a PDCP layer, an RLC layer, a MAC layer, and a PHY layer. Also, the control plane processing by the baseband processor 1603 may include processing of a Non-Access Stratum (NAS) protocol, an RRC protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0189] The baseband processor 1603 may perform MIMO encoding and precoding for beamforming.

[0190] The baseband processor 1603 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1604, which will be described later.

[0191] The application processor 1604 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1604 may include multiple processors (multiple processor cores). The application processor 1604 executes a system software program (operating system (OS)) and various application programs (e.g., a calling application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1606 or other memories, thereby realizing various functions of the UE 1.

[0192] In some implementations, the baseband processor 1603 and the application processor 1604 may be integrated on a single chip, as shown by the dashed line (1605) in Figure 16. In other words, the baseband processor 1603 and the application processor 1604 may be implemented as a single System on Chip (SoC) device 1605. An SoC device may also be called a system Large Scale Integration (LSI) or chipset.

[0193] The memory 1606 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1606 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1606 may include an external memory device accessible from the baseband processor 1603, the application processor 1604, and the SoC 1605. The memory 1606 may also include an internal memory device integrated within the baseband processor 1603, the application processor 1604, or the SoC 1605. Furthermore, the memory 1606 may include memory within a Universal Integrated Circuit Card (UICC).

[0194] The memory 1606 may store one or more software modules (computer programs) 1607 containing instructions and data for processing by the UE 1. In some implementations, the baseband processor 1603 or the application processor 1604 may be configured to read and execute the software modules 1607 from the memory 1606 to perform the processing of the UE 1 described in one or more of the embodiments.

[0195] It should be noted that the control plane processing and operations performed by UE 1 described in the above embodiment can be realized by elements other than the RF transceiver 1601 and the antenna array 1602, namely, at least one of the baseband processor 1603 and the application processor 1604, and the memory 1606 storing the software module 1607.

[0196] FIG. 17 is a block diagram showing an example configuration of a RAN node 3. Referring to FIG. 17, the RAN node 3 includes an RF transceiver 1701, a network interface 1703, a processor 1704, and a memory 1705. The RF transceiver 1701 performs analog RF signal processing for communication with a UE 1. The RF transceiver 1701 may include multiple transceivers. The RF transceiver 1701 is coupled to an antenna array 1702 and a processor 1704. The RF transceiver 1701 receives modulation symbol data from the processor 1704, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1702. The RF transceiver 1701 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1702 and provides the baseband receive signal to the processor 1704. The RF transceiver 1701 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0197] The network interface 1703 is used to communicate with network nodes (e.g., other RAN nodes, and control and forwarding nodes of the core network), and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0198] The processor 1704 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1704 may include multiple processors. For example, the processor 1704 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a CPU or MPU) that performs control plane processing. The processor 1704 may include a digital beamformer module for beamforming. The digital beamformer module may include a MIMO encoder and a precoder.

[0199] The memory 1705 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, SRAM or DRAM, or a combination thereof. The non-volatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. The memory 1705 may include storage located remotely from the processor 1704. In this case, the processor 1704 may access the memory 1705 via the network interface 1703 or other I / O interface.

[0200] The memory 1705 may store one or more software modules (computer programs) 1706 containing instructions and data for processing by the RAN node 3. In some implementations, the processor 1704 may be configured to read and execute the software modules 1706 from the memory 1705 to perform the processing of the RAN node 3 described in one or more of the embodiments.

[0201] It should be noted that the control plane processing and operations performed by the RAN node 3 described in the above embodiment can be realized by elements other than the RF transceiver 1701 and the antenna array 1702, namely the processor 1704 and the memory 1705 storing the software module 1706.

[0202] As described with reference to Figures 16 and 17, each of the processors included in the UE 1 and the RAN node 3 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0203] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0204] For example, some or all of the above embodiments may also be described as, but are not limited to, the following appendices. Some or all of the elements (e.g., configurations and functions) described in appendices directed to devices (e.g., wireless terminals, RAN nodes) may naturally also be described as appendices directed to methods and programs. For example, some or all of the elements described in appendices 2-13, which are dependent on appendices 1-13, may also be described as appendices dependent on appendices 14 and 15, due to the same dependency relationship as appendices 2-13. Similarly, some or all of the elements described in appendices 17-25, which are dependent on appendices 16, may also be described as appendices dependent on appendices 26 and 27, due to the same dependency relationship as appendices 17-25. Some or all of the elements described in any appendice may be applicable to various hardware, software, recording means for recording software, systems, and methods.

[0205] (Supplementary Note 1) A wireless terminal comprising: means for determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting or receiving PDUs of a PDU layer to or from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 2) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on an intended use case of the PDUs. (Supplementary Note 3) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by the radio access network based on the intended use case of the PDUs. (Supplementary Note 4) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a device type of the wireless terminal. (Supplementary Note 5) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by the radio access network based on a device type of the wireless terminal. (Supplementary Note 6) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case of a plurality of predefined use cases and a device type of the wireless terminal of a plurality of predefined device types.(Supplementary Note 7) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by the radio access network based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case among a plurality of predefined use cases and a device type of the wireless terminal among a plurality of predefined device types. (Supplementary Note 8) The wireless terminal of Supplementary Note 6 or 7, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with one or both of at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defines respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 9) The wireless terminal of Supplementary Note 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 for each of a plurality of QoS flows belonging to the same PDU session. (Supplementary Note 10) The wireless terminal according to Supplementary Note 1, wherein the determining means is configured to determine, for each of a plurality of data radio bearers associated with a same PDU session, whether to include the RLC sublayer in Layer 2. (Supplementary Note 11) The wireless terminal according to any one of Supplements 1 to 10, wherein the determining means is further configured to determine, for each data radio bearer, QoS flow, network slice, PDU session, use case, or device type, whether to include a Packet Data Convergence Protocol (PDCP) sublayer in Layer 2.(Supplementary Note 12) The wireless terminal according to any one of Supplements 1 to 11, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X). (Supplementary Note 13) The wireless terminal according to any one of Supplements 1 to 12, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device. (Supplementary Note 14) A method performed by a wireless terminal, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, and providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 15) A program for causing a computer to perform a method for a wireless terminal, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, and providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio access network via a physical layer according to the specific radio access technology.(Supplementary Note 16) A radio access network node comprising: means for determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 17) The radio access network node according to Supplementary Note 16, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on an intended use case of the PDUs. (Supplementary Note 18) The radio access network node according to Supplementary Note 16, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a device type of the radio terminal. (Supplementary Note 19) The radio access network node according to Supplementary Note 16, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case among a plurality of predefined use cases and a device type of the radio terminal among a plurality of predefined device types. (Supplementary Note 20) The radio access network node according to Supplementary Note 19, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with one or both of at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters.(Supplementary note 21) The radio access network node according to Supplementary note 16, wherein the determining means is configured to determine whether the RLC sublayer is to be included in the Layer 2 for each of a plurality of QoS flows belonging to the same PDU session. (Supplementary note 22) The radio access network node according to Supplementary note 16, wherein the determining means is configured to determine whether the RLC sublayer is to be included in the Layer 2 for each of a plurality of data radio bearers associated with the same PDU session. (Supplementary note 23) The radio access network node according to any one of Supplements 16 to 22, wherein the determining means is further configured to determine whether a Packet Data Convergence Protocol (PDCP) sublayer is to be included in the Layer 2 for each data radio bearer, QoS flow, network slice, PDU session, use case or device type. (Supplementary note 24) The radio access network node according to any one of Supplements 16 to 23, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X). (Supplementary note 25) The radio access network node according to any one of Supplements 16 to 24, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.(Supplementary Note 26) A method performed by a radio access network node, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, and providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 27) A program for causing a computer to perform a method for a radio access network node, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, and providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving PDUs from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 28) A wireless terminal comprising: means for determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers, based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.(Supplementary Note 29) The wireless terminal according to Supplementary Note 28, wherein the first number of sublayers include a Packet Data Convergence Protocol (PDCP) sublayer, a Radio Link Control (RLC) sublayer, and a Medium Access Control (MAC) sublayer, and the second number of sublayers include a modified PDCP sublayer and a modified MAC sublayer by integrating a retransmission function of RLC Service Data Units (SDUs) in the RLC sublayer into the PDCP sublayer and integrating a segmentation function of RLC SDUs in the RLC sublayer into the MAC sublayer. (Supplementary Note 30) The wireless terminal according to Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on an intended use case of the PDUs. (Supplementary Note 31) The wireless terminal of Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers at least in accordance with configuration information generated by the radio access network based on an intended use case of the PDUs. (Supplementary Note 32) The wireless terminal of Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers at least in accordance with configuration information generated by the radio access network based on a device type of the wireless terminal. (Supplementary Note 33) The wireless terminal of Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers at least in accordance with configuration information generated by the radio access network based on a device type of the wireless terminal. (Supplementary Note 34) The wireless terminal according to Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers based at least on a terminal capability set of the wireless terminal.(Supplementary Note 35) The wireless terminal according to Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers in accordance with at least configuration information generated by the radio access network based on a terminal capability set of the wireless terminal. (Supplementary Note 36) The wireless terminal according to Supplementary Note 34 or 35, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 37) The wireless terminal according to Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers for each of a plurality of QoS flows belonging to the same PDU session. (Supplementary Note 38) The wireless terminal according to Supplementary Note 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers for each of a plurality of data radio bearers associated with the same PDU session. (Supplementary Note 39) The wireless terminal according to any one of Supplements 28 to 38, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X). (Supplementary Note 40) The wireless terminal according to any one of Supplements 28 to 39, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.(Supplementary Note 41) A method performed by a wireless terminal, comprising: determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 42) A program for causing a computer to perform a method for a wireless terminal, comprising: determining, based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, whether to use a first number of sublayers in Layer 2 according to a specific radio access technology, or whether to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.(Supplementary Note 43) A radio access network node comprising: means for determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 44) The radio access network node according to Supplementary Note 43, wherein the first number of sublayers include a Packet Data Convergence Protocol (PDCP) sublayer, a Radio Link Control (RLC) sublayer, and a Medium Access Control (MAC) sublayer, and the second number of sublayers include a modified PDCP sublayer and a modified MAC sublayer by integrating a retransmission function of RLC Service Data Units (SDUs) in the RLC sublayer into the PDCP sublayer and integrating a segmentation function of RLC SDUs in the RLC sublayer into the MAC sublayer. (Supplementary Note 45) The radio access network node according to Supplementary Note 43 or 44, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on an intended use case of the PDUs. (Supplementary Note 46) The radio access network node according to Supplementary Note 43 or 44, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on a device type of the radio terminal.(Supplementary Note 47) The radio access network node according to Supplementary Note 43 or 44, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers based at least on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case among a plurality of predefined use cases and a device type of the radio terminal among a plurality of predefined device types. (Supplementary Note 48) The radio access network node according to Supplementary Note 47, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with one or both of at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 49) The radio access network node according to Supplementary Note 43 or 44, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers for each of a plurality of QoS flows belonging to the same PDU session. (Supplementary Note 50) The radio access network node according to Supplementary Note 43 or 44, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers for each of a plurality of data radio bearers associated with the same PDU session. (Supplementary Note 51) The radio access network node according to any one of Supplementary Notes 43 to 50, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).(Supplementary Note 52) The radio access network node according to any one of Supplementary Notes 43 to 51, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device. (Supplementary Note 53) A method performed by a radio access network node, comprising: determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing the Layer 2 for transmitting PDUs of a PDU layer to or receiving from a radio terminal via a physical layer according to the specific radio access technology.(Supplementary Note 54) A program for causing a computer to perform a method for a radio access network node, comprising: providing a Layer 2 according to a specific radio access technology for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology; and determining whether to use a first number of sublayers in the Layer 2 according to the specific radio access technology or to use a second number of sublayers less than the first number in the Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers, based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing the Layer 2 for transmitting or receiving PDU layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 55) A wireless terminal comprising: means for determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and means for providing Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 56) The wireless terminal according to Supplementary Note 55, wherein the at least one function includes segmentation of RLC Service Data Units (SDUs) in Acknowledged Mode data transfer performed in a Radio Link Control (RLC) sub-layer.(Supplementary Note 57) The wireless terminal according to Supplementary Note 55 or 56, wherein the at least one function includes integrity protection and integrity verification performed in a Packet Data Convergence Protocol (PDCP) sublayer. (Supplementary Note 58) The wireless terminal according to any one of Supplements 55 to 57, wherein the determining means is configured to determine whether to enable or disable the at least one function based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case among a plurality of predefined use cases and a device type of the wireless terminal among a plurality of predefined device types. (Supplementary Note 59) The wireless terminal according to Supplementary Note 58, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 60) The wireless terminal according to any one of Supplementary Notes 55 to 59, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X). (Supplementary Note 61) The wireless terminal according to any one of Supplementary Notes 55 to 60, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.(Supplementary Note 62) A method performed by a wireless terminal, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type, and providing the Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 63) A program for causing a computer to perform a method for a wireless terminal, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type, and providing the Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 64) A radio access network node comprising: means for determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and means for providing Layer 2 for transmitting Protocol Data Unit (PDU) PDUs to or receiving from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 65) The radio access network node according to Supplementary Note 64, wherein the at least one function includes segmentation of RLC Service Data Units (SDUs) in Acknowledged Mode data transfer, performed in a Radio Link Control (RLC) sub-layer. (Supplementary Note 66) The radio access network node according to Supplementary Note 64 or 65, wherein the at least one function includes integrity protection and integrity verification performed in a Packet Data Convergence Protocol (PDCP) sub-layer.(Supplementary Note 67) The radio access network node according to any one of Supplements 64 to 66, wherein the determining means is configured to determine whether to enable or disable the at least one function based on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case among a plurality of predefined use cases and a device type of the radio terminal among a plurality of predefined device types. (Supplementary Note 68) The radio access network node according to Supplementary Note 67, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defines respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 69) The radio access network node according to any one of Supplements 64 to 68, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X). (Supplementary Note 70) The radio access network node according to any one of Supplements 64 to 69, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.(Supplementary Note 71) A method performed by a radio access network node, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type, and providing Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 72) A program for causing a computer to perform a method for a radio access network node, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type, and providing Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 73) A wireless terminal comprising: means for selecting a plurality of functions to be used in a Layer 2 according to a specific radio access technology from a set of predefined Layer 2 functions based on one or both of a use case and a device type; and means for providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 74) The wireless terminal of Supplementary Note 73 further comprising means for configuring the Layer 2 by assigning the selected plurality of functions to two or more sublayers within the Layer 2.(Supplementary Note 75) The wireless terminal according to Supplementary Note 73 or 74, wherein the predefined Layer 2 capability set includes any combination of header compression of Service Data Units (SDUs), integrity protection, ciphering, segmentation of SUDs, acknowledged mode data transfer, unacknowledged mode data transfer, logical channel prioritization, multiplexing of SDUs, error correction with Hybrid Automatic Repeat Request, and random access procedures. (Supplementary Note 76) The wireless terminal according to any one of Supplements 73 to 75, wherein the selecting means is configured to select the plurality of functions to be used in the Layer 2 based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case of a plurality of predefined use cases and a device type of the wireless terminal of a plurality of predefined device types. (Supplementary Note 77) The wireless terminal according to Supplementary Note 76, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defines respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 78) The wireless terminal according to any one of Supplements 73 to 77, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).(Supplementary Note 79) The wireless terminal according to any one of Supplements 73 to 78, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device. (Supplementary Note 80) A method performed by a wireless terminal, comprising: selecting, based on one or both of a use case and a device type, a plurality of functions to be used in Layer 2 according to a specific radio access technology from a predefined set of Layer 2 functions, and providing the Layer 2 to transmit or receive Protocol Data Unit (PDU) layer PDUs to or from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 81) A program for causing a computer to perform a method for a wireless terminal, comprising: selecting, based on one or both of a use case and a device type, a plurality of functions to be used in Layer 2 according to a specific radio access technology from a predefined set of Layer 2 functions, and providing the Layer 2 to transmit or receive Protocol Data Unit (PDU) layer PDUs to or from a radio access network via a physical layer according to the specific radio access technology. (Supplementary Note 82) A radio access network node comprising: means for selecting a plurality of functions to be used in Layer 2 according to a specific radio access technology from a set of predefined Layer 2 functions based on one or both of a use case and a device type; and means for providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 83) A radio access network node according to Supplementary Note 82, further comprising means for configuring the Layer 2 by allocating the selected plurality of functions to two or more sublayers within the Layer 2.(Supplementary Note 84) The radio access network node according to Supplementary Note 82 or 83, wherein the predefined Layer 2 capability set includes any combination of header compression of Service Data Units (SDUs), integrity protection, ciphering, segmentation of SUDs, acknowledged mode data transfer, unacknowledged mode data transfer, logical channel prioritization, multiplexing of SDUs, error correction with Hybrid Automatic Repeat Request, and random access procedures. (Supplementary Note 85) The radio access network node according to any one of Supplementary Notes 82 to 84, wherein the selecting means is configured to select the plurality of functions to be used in the Layer 2 based on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case of a plurality of predefined use cases and a device type of the radio terminal of a plurality of predefined device types. (Supplementary Note 86) The radio access network node according to Supplementary Note 85, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters. (Supplementary Note 87) The radio access network node according to any one of Supplements 82 to 86, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).(Supplementary Note 88) The radio access network node according to any one of Supplements 82 to 87, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device. (Supplementary Note 89) A method performed by a radio access network node, comprising: selecting, based on one or both of a use case and a device type, from a predefined set of Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology, and providing the Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology. (Supplementary Note 90) A program for causing a computer to perform a method for a radio access network node, comprising: selecting, based on one or both of a use case and a device type, from a predefined set of Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology, and providing the Layer 2 for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology.

[0206] This application claims priority based on Japanese Patent Application No. 2024-133368, filed August 8, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0207] 1 UE 2 RAN 3 RAN node 4 Core network 5 AMF 6 SMF 7 UPF 8 DN 1603 Baseband processor 1604 Application processor 1606 Memory 1607 Modules 1704 Processor 1705 Memory 1706 Modules

Claims

1. A wireless terminal comprising: means for determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

2. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 based at least on an intended use case of the PDUs.

3. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by the radio access network based on an intended use case of the PDUs.

4. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a device type of the wireless terminal.

5. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least according to configuration information generated by the radio access network based on a device type of the wireless terminal.

6. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case from among a plurality of predefined use cases and a device type of the wireless terminal from among a plurality of predefined device types.

7. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 at least in accordance with configuration information generated by the radio access network based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case from among a plurality of predefined use cases and a device type of the wireless terminal from among a plurality of predefined device types.

8. The wireless terminal of claim 6 or 7, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​of a plurality of terminal capability parameters.

9. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 for each of a plurality of QoS flows belonging to the same PDU session.

10. The wireless terminal of claim 1, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 for each of a plurality of data radio bearers associated with the same PDU session.

11. The wireless terminal according to any one of claims 1 to 10, wherein the determining means is further configured to determine whether to include a Packet Data Convergence Protocol (PDCP) sublayer in Layer 2 for each data radio bearer, QoS flow, network slice, PDU session, use case, or device type.

12. The wireless terminal according to any one of claims 1 to 11, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

13. The wireless terminal according to any one of claims 1 to 12, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

14. A method performed by a wireless terminal, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

15. A program for causing a computer to perform a method for a wireless terminal, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

16. A radio access network node comprising: means for determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology.

17. The radio access network node of claim 16, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 based at least on an intended use case of the PDUs.

18. The radio access network node according to claim 16, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 based at least on a device type of the radio terminal.

19. A radio access network node according to claim 16, wherein the determining means is configured to determine whether to include the RLC sublayer in Layer 2 based at least on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the radio terminal from a plurality of predefined device types.

20. The radio access network node of claim 19, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

21. The radio access network node according to claim 16, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 for each of a plurality of QoS flows belonging to the same PDU session.

22. The radio access network node according to claim 16, wherein the determining means is configured to determine whether to include the RLC sublayer in the Layer 2 for each of a plurality of data radio bearers associated with the same PDU session.

23. A radio access network node according to any one of claims 16 to 22, wherein the determining means is further configured to determine whether to include a Packet Data Convergence Protocol (PDCP) sublayer in Layer 2 for each data radio bearer, QoS flow, network slice, PDU session, use case, or device type.

24. The radio access network node according to any one of claims 16 to 23, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

25. A radio access network node according to any one of claims 16 to 24, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

26. A method performed by a radio access network node, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology.

27. A program for causing a computer to perform a method for a radio access network node, comprising: determining whether to include a Radio Link Control (RLC) sublayer in Layer 2 according to a specific radio access technology based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a wireless terminal via a physical layer according to the specific radio access technology.

28. A wireless terminal comprising: means for determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

29. The wireless terminal of claim 28, wherein the first number of sublayers includes a Packet Data Convergence Protocol (PDCP) sublayer, a Radio Link Control (RLC) sublayer, and a Medium Access Control (MAC) sublayer, and the second number of sublayers includes a modified PDCP sublayer and a modified MAC sublayer by integrating a retransmission function of RLC Service Data Units (SDUs) in the RLC sublayer into the PDCP sublayer and integrating a segmentation function of RLC SDUs in the RLC sublayer into the MAC sublayer.

30. The wireless terminal of claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers based at least on an intended use case of the PDUs.

31. The radio terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers in accordance with at least configuration information generated by the radio access network based on an intended use case of the PDUs.

32. The wireless terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on a device type of the wireless terminal.

33. The wireless terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers in accordance with at least configuration information generated by the radio access network based on a device type of the wireless terminal.

34. A wireless terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on a terminal capability set of the wireless terminal.

35. A radio terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers in accordance with at least configuration information generated by the radio access network based on a terminal capability set of the radio terminal.

36. The wireless terminal of claim 34 or 35, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

37. The wireless terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers for each of a plurality of QoS flows belonging to the same PDU session.

38. The wireless terminal according to claim 28 or 29, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers for each of a plurality of data radio bearers associated with the same PDU session.

39. The wireless terminal according to any one of claims 28 to 38, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

40. The wireless terminal according to any one of claims 28 to 39, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

41. A method performed by a wireless terminal, comprising: determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

42. A program for causing a computer to perform a method for a wireless terminal, comprising: determining, based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type, whether to use a first number of sublayers in Layer 2 according to a specific radio access technology, or whether to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio access network via a physical layer according to the specific radio access technology.

43. A radio access network node comprising: means for determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and means for providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology.

44. The radio access network node of claim 43, wherein the first number of sublayers includes a Packet Data Convergence Protocol (PDCP) sublayer, a Radio Link Control (RLC) sublayer, and a Medium Access Control (MAC) sublayer, and the second number of sublayers includes a modified PDCP sublayer and a modified MAC sublayer by integrating a retransmission function of RLC Service Data Units (SDUs) in the RLC sublayer into the PDCP sublayer and integrating a segmentation function of RLC SDUs in the RLC sublayer into the MAC sublayer.

45. A radio access network node according to claim 43 or 44, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers based at least on an intended use case of the PDUs.

46. ​​A radio access network node according to claim 43 or 44, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on a device type of the radio terminal.

47. A radio access network node according to claim 43 or 44, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers based at least on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the radio terminal from a plurality of predefined device types.

48. The radio access network node of claim 47, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

49. A radio access network node according to claim 43 or 44, wherein the determining means is configured to determine whether to use the first number of sub-layers or the second number of sub-layers for each of a plurality of QoS flows belonging to the same PDU session.

50. A radio access network node according to claim 43 or 44, wherein the determining means is configured to determine whether to use the first number of sublayers or the second number of sublayers for each of a plurality of data radio bearers associated with the same PDU session.

51. A radio access network node according to any one of claims 43 to 50, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

52. A radio access network node according to any one of claims 43 to 51, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

53. A method performed by a radio access network node, comprising: determining whether to use a first number of sublayers in Layer 2 according to a specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing Layer 2 for transmitting PDUs of a PDU layer to or receiving them from a radio terminal via a physical layer according to the specific radio access technology.

54. A program for causing a computer to perform a method for a radio access network node, comprising: providing a Layer 2 according to a specific radio access technology for transmitting or receiving Protocol Data Unit (PDU) layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology; and determining whether to use a first number of sublayers in Layer 2 according to the specific radio access technology or to use a second number of sublayers less than the first number in Layer 2 by transferring or integrating at least one function provided by one or more sublayers included in the first number of sublayers into one or more other sublayers included in the first number of sublayers, based on at least one of a data radio bearer, a Quality of Service (QoS) flow, a network slice, a Protocol Data Unit (PDU) session, a use case, or a device type; and providing the Layer 2 for transmitting or receiving PDU layer PDUs to or from a radio terminal via a physical layer according to the specific radio access technology.

55. A wireless terminal comprising: means for determining whether to enable or disable at least one function in at least one sublayer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and means for providing Layer 2 with Protocol Data Unit (PDU) layer PDUs for transmission to or reception from a radio access network via a physical layer according to the specific radio access technology.

56. The wireless terminal of claim 55, wherein the at least one function includes segmentation of RLC Service Data Units (SDUs) in Acknowledged Mode data transfer, performed at a Radio Link Control (RLC) sublayer.

57. The wireless terminal of claim 55 or 56, wherein the at least one function includes integrity protection and integrity verification performed at a Packet Data Convergence Protocol (PDCP) sublayer.

58. A wireless terminal according to any one of claims 55 to 57, wherein the determining means is configured to determine whether to enable or disable the at least one feature based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the wireless terminal from a plurality of predefined device types.

59. The wireless terminal of claim 58, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

60. The wireless terminal according to any one of claims 55 to 59, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

61. A wireless terminal according to any one of claims 55 to 60, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

62. A method performed by a wireless terminal, comprising: determining whether to enable or disable at least one function in at least one sublayer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and providing Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology.

63. A program for causing a computer to perform a method for a wireless terminal, comprising: determining whether to enable or disable at least one function in at least one sublayer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and providing Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology.

64. A radio access network node comprising: means for determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and means for providing Layer 2 with Protocol Data Unit (PDU) layer PDUs for transmission to or reception from a radio terminal via a physical layer according to the specific radio access technology.

65. The radio access network node of claim 64, wherein the at least one function comprises segmentation of RLC Service Data Units (SDUs) in Acknowledged Mode data transfer, performed at the Radio Link Control (RLC) sublayer.

66. A radio access network node according to claim 64 or 65, wherein the at least one function includes integrity protection and integrity verification performed at a Packet Data Convergence Protocol (PDCP) sublayer.

67. A radio access network node according to any one of claims 64 to 66, wherein the determining means is configured to determine whether to enable or disable the at least one feature based on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the radio terminal from a plurality of predefined device types.

68. The radio access network node of claim 67, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

69. A radio access network node according to any one of claims 64 to 68, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

70. A radio access network node according to any one of claims 64 to 69, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

71. A method performed by a radio access network node, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and providing Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio terminal via a physical layer according to the specific radio access technology.

72. A program for causing a computer to perform a method for a radio access network node, comprising: determining whether to enable or disable at least one function in at least one sub-layer included in Layer 2 according to a specific radio access technology based on one or both of a use case and a device type; and providing Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a wireless terminal via a physical layer according to the specific radio access technology.

73. A wireless terminal comprising: means for selecting, based on one or both of a use case and a device type, a plurality of functions to be used in a Layer 2 according to a specific radio access technology from a set of predefined Layer 2 functions; and means for providing the Layer 2 with Protocol Data Unit (PDU) layer PDUs for transmission to or reception from a radio access network via a physical layer according to the specific radio access technology.

74. The wireless terminal of claim 73, further comprising: means for configuring said Layer 2 by assigning said selected functions to two or more sublayers within said Layer 2.

75. The wireless terminal of claim 73 or 74, wherein the predefined Layer 2 feature set includes any combination of header compression, integrity protection, ciphering, segmentation of Service Data Units (SDUs), Acknowledged Mode data transfer, Unacknowledged Mode data transfer, logical channel prioritization, multiplexing of SDUs, error correction with Hybrid Automatic Repeat Request, and random access procedures.

76. A wireless terminal according to any one of claims 73 to 75, wherein the selecting means is configured to select the plurality of functions to be used in the layer 2 based on a terminal capability set of the wireless terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the wireless terminal from a plurality of predefined device types.

77. The wireless terminal of claim 76, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

78. The wireless terminal according to any one of claims 73 to 77, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

79. A wireless terminal according to any one of claims 73 to 78, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

80. A method performed by a wireless terminal, comprising: selecting, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology; and providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology.

81. A program for causing a computer to perform a method for a wireless terminal, comprising: selecting, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology; and providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a radio access network via a physical layer according to the specific radio access technology.

82. A radio access network node comprising: means for selecting, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology; and means for providing the Layer 2 with Protocol Data Unit (PDU) layer PDUs for transmission to or reception from a radio terminal via a physical layer according to the specific radio access technology.

83. A radio access network node according to claim 82, further comprising means for configuring said Layer 2 by allocating said selected functions to two or more sublayers within said Layer 2.

84. A radio access network node according to claim 82 or 83, wherein the predefined set of Layer 2 features includes any combination of header compression, integrity protection, ciphering of Service Data Units (SDUs), segmentation of SDUs, acknowledged mode data transfer, unacknowledged mode data transfer, logical channel prioritization, multiplexing of SDUs, error correction with Hybrid Automatic Repeat Request, and random access procedures.

85. A radio access network node according to any one of claims 82 to 84, wherein the selecting means is configured to select the plurality of functions to be used in the layer 2 based on a terminal capability set of the radio terminal, the terminal capability set being associated with one or both of an intended use case from a plurality of predefined use cases and a device type of the radio terminal from a plurality of predefined device types.

86. The radio access network node of claim 85, wherein the terminal capability set is one of a plurality of predefined terminal capability sets, each terminal capability set being predefined in association with at least one of the plurality of predefined use cases and at least one of the plurality of predefined device types, and each terminal capability set defining respective values ​​for a plurality of terminal capability parameters.

87. A radio access network node according to any one of claims 82 to 86, wherein the use case is enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), eXtended Reality (XR), Non-Terrestrial Networks (NTN), Internet of Things (IoT), Uncrewed Aerial Vehicles (UAV), or vehicle-to-everything (V2X).

88. A radio access network node according to any one of claims 82 to 87, wherein the device type is a handheld device, a robotics device, a wearable device, a sensor device, or an automotive device.

89. A method performed by a radio access network node, comprising: selecting, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology; and providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a wireless terminal via a physical layer according to the specific radio access technology.

90. A program for causing a computer to perform a method for a radio access network node, comprising: selecting, based on one or both of a use case and a device type, from a set of predefined Layer 2 functions, a plurality of functions to be used in Layer 2 according to a specific radio access technology; and providing the Layer 2 for transmitting Protocol Data Unit (PDU) layer PDUs to or receiving from a wireless terminal via a physical layer according to the specific radio access technology.

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