Wireless terminal and method thereof

Abstract

To provide operation when a set of random access resources associated with a feature or feature combination selected, desired, or intended by a wireless terminal is not available.SOLUTION: A wireless terminal receives information about slices from a core network and system information including a random access configuration from a radio access network node. When a first set of random access resources associated with a feature or feature combination selected, desired, or intended by the wireless terminal is available, the wireless terminal performs a random access preamble transmission using a random access resource selected from the first set, and otherwise performs the random access preamble transmission using a random access resource selected from a second set of random access resources not associated with the feature or feature combination.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to wireless communication networks, and more particularly to random access and cell (re)selection. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP®) Radio Access Network (RAN) Working Group is currently considering additional random access resource partitioning support. This feature is expected to be introduced in 3GPP Release 17 (see, for example, non-patent documents 1-4). Random access resource partitioning partitions the random access resources used for random access preamble transmission. Random access resource partitioning allows a wireless terminal (e.g., User Equipment (UE)) to inform a radio access network node (e.g., gNB, eNB) about the resources used for random access preamble transmission.

[0003] In this specification, random access resources refer to random access preambles or combinations of random access occasions and random access preambles. Random access resource partitioning is also called Random Access Channel (RACH) resource partitioning or RACH partitioning. Random access opportunities are also called RACH occasions (ROs), and random access preambles are also called RACH preambles. One RACH occasion is a time and frequency resource for RACH preamble transmission. According to the current 3GPP Release 15 and Release 16 specifications, one RACH occasion has a maximum of 64 RACH preambles available for transmission.

[0004] In 3GPP Release 16 RACH partitioning, the UE can inform the gNB of the following information depending on which RACH preamble it uses: - Selected Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) (or selected beam) - Contention-Free Random Access (CFRA) or Contention-Based RA (CBRA) cause - Payload size (preamble group B configured or not) - Random access type (2-Step or 4-step RA)

[0005] To allow the network (e.g., gNB) to identify features early, additional RACH partitioning is being considered for some Release 17 features. These features include, for example, Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CE or CovEnh), and Slicing. All RACH resource partitions resulting from possible feature combinations or combinations of features must be configured. Possible feature combinations include, for example, RedCap+SDT, RedCap+CovEnh, RedCap+Slicing, RedCap+SDT+CovEnh, RedCap+SDT+Slicing, RedCap+CovEnh+Slicing, etc. Features may also be referred to as functional features.

[0006] The RedCap indication on the RACH is used to indicate reduced capabilities to the network in the first RACH message (MSG1 in 4-step RA, MSGA in 2-step RA), allowing the network to adapt subsequent transmissions.

[0007] The SDT indication on the RACH is used to indicate the SDT to the network and request a larger third RACH message (MSG3) size, or to indicate a larger MSGA size (the size of the data portion of the MSGA) in the case of a 2-step RA.

[0008] The CovEnh indication on the RACH is used to indicate the need for coverage enhancement, for example, to request repetition of the third RACH message (MSG3 in 4-step RA). The CovEnh indication may be binary information to indicate whether Msg3 PUSCH repetition is required or not.

[0009] The slicing indication on the RACH indicates prioritized slices to the network and is used to achieve slice isolation for the RACH as well. The slicing indication may be binary information to distinguish between prioritized and non-prioritized network slices. Alternatively, the slicing indication may indicate multi-level slice priority, a selected or intended network slice, or a selected or intended network slice group, which would further increase the number of partitions.

[0010] Furthermore, the 3GPP RAN Working Group is considering enhancements to cell selection and reselection for slicing. These features are also planned to be introduced in 3GPP Release 17 (see, for example, Non-Patent Documents 5-8). These features are also called slice-based (or slice-group-based) cell (re)selection. This enables the Access Stratum (AS) layer of a UE to preferentially select or reselect a cell that supports the intended network slice (or network slice group). The intended network slice (or network slice group) is indicated to the AS layer of the UE by the Non-Access Stratum (NAS) layer of the UE. [Prior art documents] [Non-patent literature]

[0011] [Non-licensed document 1] ZTE Corporation, "RRC and MAC related aspects of common RACH configuration", R2-2107484, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-licensed document 2] NEC, "General aspects of RACH indication and partitioning", R2-2108138, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-licensed document 3] Ericsson, "RACH partitioning for Rel-17 features", R2-2108253, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021

Non-licensed Document 4

Non-licensed Document 5

Non-licensed Document 6

[0012] The inventors have investigated random access resource partitioning for Release 17 features and feature combinations and have identified various challenges.

[0013] One of these challenges concerns the interaction between the UE NAS layer and the UE AS layer in selecting feature combinations. For example, as mentioned above, new Release 17 features currently envisioned for additional RACH partitioning include "Slicing." Whether slicing indication on the RACH is required is considered to depend on the network slice (or slice group) intended by the UE NAS layer. Meanwhile, the selection of RACH resources based on feature combinations is performed by the UE AS layer. In such cases, it is unclear how the interaction between the UE NAS layer and the UE AS layer is performed to determine feature combinations or select random access resources corresponding to the feature combinations.

[0014] Another of these challenges relates to cell selection or reselection, or both. The inventors believe that during cell selection and reselection, it may be desirable for a UE to preferentially select cells that support random access based on Release 17 features or feature combinations. Random access based on Release 17 features or feature combinations allows the UE to provide the network with an early indication of the Release 17 features or feature combinations via the random access resources used for preamble transmission. However, it has not yet been discussed that the availability of random access based on features or feature combinations is taken into consideration (or prioritized) for cell selection or reselection.

[0015] One of the objectives of the embodiments disclosed herein is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems related to random access resource partitioning, including the problems described above. It should be noted that this objective is only one of the objectives of the embodiments disclosed herein. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings. [Means for solving the problem]

[0016] In a first aspect, a wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to provide a NAS layer function and an AS layer function. The NAS layer function is configured to pass information regarding a first feature to the AS layer function. The AS layer function is configured to determine a feature combination including the first feature and one or more other features derived from the information. The AS layer function is configured to select a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function. The AS layer function is configured to transmit a random access preamble on the selected random access resource.

[0017] In a second aspect, a method performed by a wireless terminal includes the following steps: (a) providing NAS layer functions and AS layer functions; (b) the NAS layer function passing information about the first characteristic to the AS layer function; (c) the AS layer function determining a feature combination including the first feature and one or more other features derived from the information; (d) the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function; and (e) the AS layer function transmitting a random access preamble on the selected random access resource;

[0018] In a third aspect, a wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to provide a NAS layer function and an AS layer function. The NAS layer function is configured to pass information indicating a feature combination to the AS layer function. The AS layer function is configured to select a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function. The AS layer function is configured to perform a random access preamble transmission on the selected random access resource.

[0019] In a fourth aspect, a method performed by a wireless terminal includes the following steps: (a) providing NAS layer functions and AS layer functions; (b) the NAS layer function passing information indicating the feature combination to the AS layer function; (c) the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function; and (d) the AS layer function transmitting a random access preamble on the selected random access resource;

[0020] In a fifth aspect, a wireless terminal includes at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to, when selecting or reselecting a cell to camp on from one or more candidate cells, consider whether the candidate cells provide a distinct set of random access resources for a selected, desired, or intended feature or feature combination.

[0021] In a sixth aspect, a method performed by a wireless terminal includes, when selecting or reselecting a cell to camp on from one or more candidate cells, considering whether the candidate cells provide a distinct set of random access resources for the selected, desired, or intended feature or feature combination.

[0022] A seventh aspect is directed to a program, which includes a set of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second, fourth, or sixth aspect. [Effects of the Invention]

[0023] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to random access resource partitioning. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a protocol stack of a control plane of a wireless terminal according to an embodiment. [Figure 3] 10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 4] FIG. 10 is a sequence diagram illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 5] 10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 6] FIG. 10 is a sequence diagram illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 7] 10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 8] 10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 9]10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 10] 10 is a flowchart illustrating an example of an operation of the wireless terminal according to the embodiment. [Figure 11] FIG. 2 is a block diagram illustrating a configuration example of a wireless terminal according to the embodiment. [Figure 12] FIG. 2 is a block diagram illustrating a configuration example of a radio access network node according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0027] Although the following embodiments will be described mainly with respect to the 3GPP fifth generation mobile communication system (5G system), these embodiments may also be applied to other wireless communication systems.

[0028] As used herein, depending on the context, "if" may be construed to mean "when," "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 construed to have the same meaning, depending on the context.

[0029] First, the configurations and operations of multiple network elements common to multiple embodiments will be described. Figure 1 illustrates an example configuration of a wireless communication system according to multiple embodiments. In the example of Figure 1, the wireless communication system includes a wireless terminal (i.e., UE) 1, a radio access network (RAN) node (e.g., gNB) 2, and a RAN node 3 (e.g., gNB). Each element (network function) illustrated in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on the dedicated hardware, or as a virtualized function instantiated on an application platform.

[0030] UE1 has at least one radio transceiver and is configured to perform cellular communication with RAN node 2 or 3, or both. RAN node 2 is configured to manage cell 21 and perform cellular communication with multiple UEs, including UE1, using a cellular communication technology (e.g., NR Radio Access Technology (RAT)). RAN node 3 is configured to manage cell 31 and perform cellular communication with multiple UEs using a cellular communication technology (e.g., NR RAT).

[0031] The RAN node 2 may be a Central Unit (e.g., gNB-CU) in a cloud RAN (C-RAN) deployment, or may be a combination of a CU and one or more Distributed Units (e.g., gNB-DUs). Similarly, the RAN node 3 may be a CU or may include a CU and one or more Distributed Units (DUs). The C-RAN is also referred to as a CU / DU split. Furthermore, the CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Thus, each of the RAN nodes 2 and 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), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB (or the RRC and PDCP protocols of the gNB). The DU may be a logical node that hosts the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of the gNB.

[0032] The RAN node 2 transmits signals including System Information (SI) 101 and other signals within the cell 21. The System Information 101 includes a Master Information Block (MIB) and many System Information Blocks (SIBs). The System Information 101 is divided into Minimum SI and Other SI. Minimum SI is always broadcast periodically and includes basic information required for initial access and information required to acquire Other SI. Other SI includes all SIBs that are not broadcast within Minimum SI. More specifically, Minimum SI includes MIB and SIB type 1 (SIB1), and Other SI includes SIB types from SIB type 2 (SIB2) onwards. Each SIB included in the Other SI is broadcast periodically at all times, broadcast on demand based on a request from UEs in RRC_IDLE or RRC_INACTIVE, or sent to UEs in RRC_CONNECTED via dedicated RRC signaling. Similarly, the RAN node 3 transmits signals including system information 102 and other signals within the cell 21. If the RAN node 2 or 3 is a C-RAN deployment, the DU (e.g., gNB-DU) may generate at least a portion of the system information (e.g., MIB, SIB1). The DU may transmit the generated system information directly to UE1 or may transmit it to a CU (e.g., gNB-CU) so that the CU can transmit it to UE1 (via the DU).

[0033] In the example of Fig. 1, UE1 selects or reselects cell 21 of RAN node 2 and camps on cell 21. In other words, cell 21 is the serving cell of UE1. Meanwhile, cell 31 is a neighboring cell of UE1's serving cell 21. Cell 21 and cell 31 may operate in the same frequency band or in different frequency bands.

[0034] In addition to cell 31, one or more other neighboring cells may exist around cell 21. Some or all of these other neighboring cells may operate in the same frequency band as cell 21, or may operate in a different frequency band.

[0035] 2 shows an example of a control plane protocol stack for UE 1. The control plane protocol stack 200 for UE 1 includes an application (APP) layer 201, a non-access stratum (NAS) layer 202, and an access stratum (AS) layer 208. The AS layer 208 includes an RRC layer 203, a PDCP layer 204, an RLC layer 205, a MAC layer 206, and a PHY layer 207.

[0036] The NAS layer 202 utilizes the data communication over the air interface and management of the air interface provided by the AS layer 208 to communicate with the core network (i.e., 5G Core (5GC)) via RAN node 2 according to the 5G System (5GS) Mobility Management (5GMM) protocol and the 5GS Session Management (5GSM) protocol. The 5GMM protocol runs between UE1 and the Access and Mobility Management Function (AMF) in the 5GC and is used for UE registration, mobility, and transport of 5GSM protocol messages. The 5GSM protocol runs between UE1 and the Session Management Function (SMF) in the 5GC via the AMF and supports management of PDU session connectivity.

[0037] The NAS layer 202 communicates with the RRC layer 203 to utilize the services provided by the AS layer 208 (i.e., data communication over the air interface between UE1 and RAN node 2 and management of the air interface). The RRC layer 203 is a lower layer of the NAS layer 202, and provides radio resource control (RRC) and manages the RRC states of UE1 (i.e., RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED).

[0038] The AS layer 208 initiates an RRC connection establishment procedure or an RRC connection resumption procedure in response to a request from the NAS layer 202 or spontaneously. For example, in response to receiving a PDU session establishment request from an upper layer (i.e., application layer 201), the NAS layer 202 initiates a registration procedure or a service request procedure to transition to 5GMM-CONNECTED mode if the 5GS mobility management (5GMM) mode is 5GMM-IDLE, and attempts to send an initial NAS message (e.g., a registration request message or a service request message) to the AMF. The initial NAS message from the NAS layer 202 triggers the AS layer 208 to establish an RRC connection between UE1 and RAN node 2. If the 5GMM mode is 5GMM-CONNECTED or 5GMM-CONNECTED with RRC inactive indication, the NAS layer 202 attempts to send a NAS message (e.g., a PDU SESSION ESTABLISHMENT REQUEST message, a UL NAS TRANSPORT message, a PDU SESSION MODIFICATION REQUEST, or a SERVICE REQUEST message) depending on the event that triggered the access attempt. Alternatively, if the 5GMM mode is 5GMM-CONNECTED or 5GMM-CONNECTED with RRC inactive indication and the access attempt was "an uplink user data packet to be sent for a PDU session with suspended user-plane resources," the NAS layer 202 requests the AS layer 208 to transition to RRC_CONNETED (or resumption of the RRC connection) in order to send an uplink user data packet (i.e., Mobile Originated (MO) data).

[0039] In response to receiving the initial NAS message or the request to transition to RRC_CONNETED, the RRC layer 203 requests or triggers the MAC layer 206 to initiate a random access procedure to send an RRC message for establishing or resuming an RRC connection. The RRC message for establishing or resuming an RRC connection may be an RRC Setup Request message or an RRC Resume Request message. Prior to this, the RRC layer 203 may perform one or more access barring checks. If the access barring checks are passed, the RRC layer 203 may request the MAC layer 206 to initiate a random access procedure. Techniques for access barring include, for example, Access Class Barring (ACB), Extended Access Barring (EAB), Application Specific Congestion Control for Data Communication (ACDC), and Unified Access Control (UAC). The RRC layer 203 may perform barring checks for one or more of these access barring techniques.

[0040] The MAC layer 206 receives triggers for the random access procedure based on events such as re-establishment and resumption of an RRC connection from the RRC layer 203, and initiates the random access procedure accordingly. The MAC layer 206 may initiate the random access procedure by itself or by Physical Downlink Control Channel (PDCCH) order.

[0041] In the random access procedure, the MAC layer 206 selects one RACH resource from a set of partitioned random access resources (RACH resources) to be used for RACH preamble transmission. The set of RACH resources includes RACH preambles or combinations of RACH occasions and RACH preambles. One RACH occasion is a time and frequency resource for RACH preamble transmission. According to the current 3GPP Release 15 and Release 16 specifications, one RACH occasion has 64 RACH preambles available for transmission. The set of RACH resources can also be referred to as a pool or partition of RACH resources.

[0042] The MAC layer 206 requests the PHY layer 207 to transmit a random access preamble (RACH preamble) on the selected RACH resource. The random access procedure further includes a Random Access Response (RAR) reception and contention resolution.

[0043] The MAC layer 206 may comply with RACH partitioning in 3GPP Release 16. In RACH partitioning in 3GPP Release 16, the UE can inform the gNB of the following information depending on which RACH preamble it uses: - Selected Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) (or selected beam) - Contention-Free Random Access (CFRA) or Contention-Based RA (CBRA) cause - Payload size (preamble group B configured or not) - Random access type (2-Step or 4-step RA)

[0044] Additionally, the MAC layer 206 supports additional RACH partitioning for Release 17 features. This allows the RAN node 2 to early identify the Release 17 features or feature combinations selected, desired, or intended by the UE 1. For example, a RACH resource partition is configured for each of all or a subset of the Release 17 features, and a RACH resource partition is configured for each possible feature combination. Each Release 17 feature may be, for example, Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CE or CovEnh), or Slicing. A feature combination may include, for example, at least two of RedCap, SDT, CovEnh, and Slicing. The term "feature" as used hereinafter in this specification refers to any of these Release 17 features unless otherwise specified. Similarly, the term "feature combination" means a combination of at least two of these Release 17 features, unless otherwise specified. A "feature combination" may also be referred to as a "feature set" or "set of features."

[0045] The RedCap indication on the RACH is used to indicate reduced capabilities to the network in the first RACH message (MSG1 in 4-step RA, MSGA in 2-step RA), allowing the network to adapt subsequent transmissions. The 3GPP RAN Working Group is currently considering New Radio (NR) support for RedCap UEs, which is expected to be introduced in 3GPP Release 17. The introduction of RedCap NR devices will enable addressing use cases not yet optimally served by current NR standards. Use cases motivating the standardization of NR RedCap include wearables (e.g., smart watches, wearable medical devices, Augmented Reality (AR) / Virtual Reality (VR) goggles), industrial wireless sensors, and video surveillance. These use cases have less stringent data rate requirements than enhanced mobile broadband (eMBB) use cases, and do not require the tight or deterministic latency requirements of time-critical communications use cases. Therefore, there is room to trade off device functionality for complexity or cost savings compared to a baseline Release 15 NR device. According to currently envisioned RedCap device capabilities, the maximum device bandwidth, minimum number of device receive branches, maximum number of downlink MIMO layers, and maximum downlink modulation order may be reduced or relaxed compared to those of a Release 15 NR device.

[0046] The SDT indication on the RACH indicates the SDT to the network and is used to request a larger third RACH message (MSG3) size. Alternatively, the SDT indication is used to indicate a larger MSGA size (the size of the data portion of the MSGA) in the case of 2-step RA. Furthermore, similar to the RACH in 3GPP Release 15 / 16, two sizes of MSG3 or MSGA may be possible. In this case, the SDT indication on the RACH may further indicate the size of MSG3 or MSGA. The SDT, also known as the SDT in inactive state, is one of the new features introduced in 3GPP Release 17. It enables UEs in RRC_INACTIVE to send infrequent and small data without requiring RRC state transitions.

[0047] The CovEnh indicator on the RACH is used to indicate the need for coverage enhancement, for example, to request repetition of the third RACH message (MSG3 in 4-step RA). The CovEnh indicator may be binary information to indicate whether Msg3 PUSCH repetition is required. Alternatively, the CovEnh indicator may indicate one of multiple coverage enhancement (CE) levels. The CovEnh indicator may indicate one of two or more CE level groups (or CE modes). One CE level group or CE mode includes one or more CE levels. For example, the CE specified in 3GPP Release 14 supports up to four CE levels (i.e., CE levels 0 to 3). The UE determines the CE level based on the measured RSRP level. CE level 0 is associated with the highest RSRP threshold, and CE level 3 is associated with the lowest RSRP threshold. In other words, a UE in CE level 0 enjoys a relatively low path loss and a high downlink received power, and a UE in CE level 3 enjoys a relatively high path loss and a low downlink received power.

[0048] The Slicing indication on the RACH indicates prioritized slices to the network and is used to achieve slice isolation for the RACH as well. The Slicing indication may be binary information to distinguish between prioritized and non-prioritized network slices. Alternatively, the Slicing indication may be information indicating one of three or more multi-level slice priorities. The Slicing indication may indicate the network slice or network slice group selected or intended by UE1. A network slice group includes one or more network slices.

[0049] Network slicing uses network function virtualization (NFV) and software-defined networking (SDN) technologies to create multiple virtualized logical networks on a physical network. Each virtualized logical network, called a network slice or network slice instance, includes logical nodes and functions and is used for specific traffic and signaling. A network slice may be provided by a core network (e.g., 5GC). Multiple network slices are distinguished by the services or use cases provided to UEs on each network slice. Use cases include, for example, enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC). These are called slice types (e.g., Slice / Service Type (SST)). The RAN node 2 may assign to the UE 1 a RAN slice and a radio slice associated with the network slice of the core network selected for the UE 1, in order to provide end-to-end network slicing to the UE 1. From the above, the Slicing indication in the RACH may be information about a network slice of the core network, information about a RAN or a radio slice, or information about an end-to-end network slice.

[0050] The network slice may be indicated by Network Slice Selection Assistance Information (NSSAI) or Single NSSAI (S-NSSAI). This may be notified, for example, from the core network (e.g., 5GC) to the NAS layer 202 of UE1, and then from the NAS layer 202 of UE1 to the AS layer 208 (e.g., RRC). The network slice selected and the intended network slice by UE1 may be referred to as the selected NSSAI and the intended NSSAI, respectively. The selected network slice (selected NSSAI) may also be referred to as the allowed NSSAI, meaning the network slice permitted for use by the core network. The SST may be included in the S-NSSAI (i.e., the S-NSSAI includes information about the SST).

[0051] More specifically, each network slice selected or intended by UE1 may be identified by an identifier known as Single Network Slice Selection Assistance Information (S-NSSAI). The selected or intended network slice may be the S-NSSAI(s) included in the Configured NSSAI or the S-NSSAI(s) included in the Allowed NSSAI. Note that the S-NSSAIs in the Requested NSSAI included in the NAS Registration Request message must be part of the Configured NSSAI and / or the Allowed NSSAI. Therefore, the intended network slice may be the S-NSSAI(s) included in the Requested NSSAI.

[0052] The Configured NSSAI includes one or more S-NSSAIs, each applicable to one or more Public Land Mobile Networks (PLMNs). The Configured NSSAI is configured by, for example, a Serving PLMN and applies to the Serving PLMN. The Allowed NSSAI is provided to UE1 by the Serving PLMN and indicates one or more S-NSSAIs that UE1 can use in the current Registration Area of ​​the Serving PLMN. The Configured NSSAI may be the Default Configured NSSAI. The Default Configured NSSAI is configured by the Home PLMN (HPLMN) and applies to any PLMNs for which a specific Configured NSSAI is not provided. UE1 may be pre-configured with the Default Configured NSSAI. UE1 may be provisioned or updated with the Default Configured NSSAI determined by the Unified Data Management (UDM) of the HPLMN. The Allowed NSSAI is determined by the AMF of the Serving PLMN, for example, during the registration procedure. The Allowed NSSAI is signaled to UE1 by the network (i.e., AMF) and stored in the respective (non-volatile) memories of the AMF and UE1.

[0053] The above describes the operation of the AS layer 208 based on NAS-initiated access attempts with reference to FIG. 2 . The operations performed by the AS layer 208 are, of course, not limited to these. In one example, the RRC layer 203 performs cell selection and reselection. Specifically, when the RRC state of UE1 is RRC_IDLE or RRC_INACTIVE, the RRC layer 203 searches for a suitable cell to camp on according to cell selection criteria or cell reselection criteria. When a suitable cell to camp on is found, the RRC layer 203 camps on the cell. Camping on a cell means that UE1 has completed the cell selection or reselection process and selected the cell. In other words, the term "camping on" means that UE1 is staying on a cell and is ready to start a potential dedicated service in the cell. In particular, when UE1 is in RRC_IDLE or RRC_INACTIVE, the serving cell of UE1 can be referred to as the cell on which UE1 is camped. The serving cell may also be referred to as a camped cell.

[0054] In some implementations, the AS layer 208 may determine or select the feature combination. In one example, the RRC layer 203 of UE1 may determine or select the feature combination. Specifically, the RRC layer 203 of UE1 may determine the feature combination and indicate the determined feature combination to the MAC layer 206 of UE1. Alternatively, the final determination or selection of the feature combination may be made by the MAC layer 206 of UE1. Specifically, the RRC layer 203 of UE1 may determine one or more features to be included in the feature combination and indicate the determined one or more features to the MAC layer 206 of UE1. The MAC layer 206 may further determine required features and determine the feature combination.

[0055] In other implementations, the NAS layer 202 may determine or select the feature combination. The NAS layer 208 may indicate the feature combination to the AS layer 208 (eg, the RRC layer 203).

[0056] First Embodiment A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0057] 3 shows an example of UE 1's behavior regarding NAS initiated access attempts. In step 301, the NAS layer 202 passes information about the first characteristic to the AS layer 208, specifically to the RRC layer 203. For example, the NAS layer 202 may send the information to the RRC layer 203 together with a request to send an NAS message. The NAS layer 202 may send the information to the RRC layer 203 together with a request to transition from RRC_IDLE or RRC_INACTIVE to RRC_CONNETED.

[0058] The first feature may relate to information, state, or functionality managed by the NAS layer 202. The first feature may relate to information, state, or functionality configured in the UE 1 by the core network via NAS signaling. The first feature may be a Release 17 feature, specifically "Slicing." In this case, the information related to the first feature may indicate one or more network slices intended by the NAS layer 202. As described above, each of the one or more intended network slices may be identified by an identifier known as an S-NSSAI. The intended network slice may be an S-NSSAI(s) included in the Configured NSSAI or an S-NSSAI(s) included in the Allowed NSSAI. The intended network slice may be an S-NSSAI(s) included in the Requested NSSAI.

[0059] Alternatively, the information regarding the first feature may indicate one or more network slice groups intended by the NAS layer 202. Each of the one or more intended network slice groups may be identified by a slice group identifier (ID). Mapping of each network slice group to one or more network slices may be provided to the UE1 (NAS layer 202) by a core network (e.g., AMF) via NAS signaling.

[0060] Alternatively, the information about the first feature may indicate one or more network slice priority levels. In other words, one or more slice groups may have one or more network slice priority levels. A mapping between each slice priority level and one or more network slices may be provided to UE1 (NAS layer 202) by a core network (e.g., AMF) via NAS signaling.

[0061] In step 302, the AS layer 208 determines a feature combination including a first feature derived from information received from the NAS layer 202 and one or more other features. The first feature and the one or more other features may be Release 17 features. Specifically, the first feature may be Slicing, and the one or more other features may include at least one of RedCap, SDT, and CovEnh. In one example, the RRC layer 203 of UE1 may determine the feature combination and indicate the determined feature combination to the MAC layer 206 of UE1. Alternatively, the RRC layer 203 of UE1 may determine one or more features to be included in the feature combination and indicate the determined one or more features to the MAC layer 206 of UE1. The MAC layer 206 may further determine required features and determine the feature combination.

[0062] In step 303, the AS layer 208 selects a random access resource from the set of random access resources associated with the feature combination determined in step 302. The set of random access resources (or RACH resources) is a separate RACH resource partition associated with the feature combination. Specifically, the RRC layer 203 may indicate the feature combination determined in step 302 to the MAC layer 206. The MAC layer 206 may select a random access resource from the set of random access resources associated with the feature combination indicated by the RRC layer 203. UE1 transmits a preamble on a random access resource selected from the resource set (or partition), thereby enabling RAN node 2 to early identify the feature combination selected, desired, or intended by UE1.

[0063] In step 304, the AS layer 208 transmits a random access preamble on the selected random access resource. Specifically, the MAC layer 206 requests the PHY layer 207 to transmit a preamble on the selected random access resource.

[0064] In step 301, the NAS layer 202 may send information about the second feature (e.g., Mobile Terminated (MT) SDT-related information) in addition to information about the first feature (e.g., slice-related information) to the AS layer 208. In this case, in step 302, the AS layer 208 may determine a feature combination including the first feature, the second feature, and one or more other features for RACH resource selection.

[0065] Figure 4 shows a specific example of the operation of UE1 described with reference to Figure 3. In step 401, the AS layer 208 of UE1 is in RRC_INACTIVE. Although not shown, if UE1 receives an RRC Release message including suspendConfig from RAN node 2 while in RRC_CONNETED, the RRC layer 203 indicates the suspension of the RRC connection to the upper layer (i.e., NAS layer 202) and enters RRC_INACTIVE. Therefore, the 5GMM mode of the NAS layer 202 is 5GMM-CONNECTED with RRC inactive indication.

[0066] In step 402, the NAS layer 202 triggers an access attempt based on an uplink user data packet transmitted for a PDU Session using suspended user plane resources. The access attempt relates to a specific network slice (e.g., Slice-X). In step 403, in response to the triggered access attempt, the NAS layer 202 requests the AS layer 208 (RRC layer 203) to transition to RRC_CONNETED (or resumption of the RRC connection) to transmit an uplink user data packet (i.e., MO data). The request indicates a specific network slice (e.g., Slice-X) to the RRC layer 203. Note that the NAS layer 202 may also indicate a specific network slice group or a specific network slice priority level to the RRC layer 203. Step 403 corresponds to step 301 in FIG. 3.

[0067] Step 404 corresponds to step 302 in FIG. 3. In step 404, the AS layer 208 executes a joint process. Specifically, the RRC layer 203 determines whether the network slice (or slice group) indicated by the NAS layer 202 is a prioritized network slice for RACH preamble transmission. Alternatively, the RRC layer 203 determines whether the network slice (or slice group, or priority level) indicated by the NAS layer 202 is a prioritized network slice for RACH preamble transmission. In addition, the RRC layer 203 determines whether to perform SDT. In other words, the RRC layer 203 determines whether to perform SDT or a normal RRC resumption procedure. Based on these decisions, the RRC layer 203 determines a feature combination (e.g., SDT+Slicing) and passes it to the MAC layer 206. In step 405, the MAC layer 206 determines, according to the feature combination indicated by the RRC layer 203, a RACH resource for RACH preamble transmission from the set (or partition) of RACH resources associated with the feature combination.

[0068] According to the operation of UE1 described with reference to Figure 3 and / or Figure 4, the AS layer 208 can determine a feature combination that includes features related to information (or status, or functionality) managed by the NAS layer 202. This can therefore provide an interaction between the NAS layer 202 and the AS layer 208 of UE1 for determining the feature combination.

[0069] Note that in step 303 of Fig. 3 or step 405 of Fig. 4, if the set of random access resources associated with the feature combination is not configured (or is not available) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may notify the NAS layer 202 of a failure without transmitting the random access preamble. The failure cause sent by the AS layer 208 to the NAS layer 202 may be "other" or a newly defined value. Alternatively, the AS layer 208 may perform any of the fallback operations described in detail in the third or fourth embodiment below.

[0070] <Second embodiment> A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0071] Figure 5 shows a different solution from that of Figure 3. In step 501, the NAS layer 202 passes information indicating a feature combination to the AS layer 208, specifically to the RRC layer 203. For example, the NAS layer 202 may send the information to the RRC layer 203 together with a request to transmit a NAS message. The NAS layer 202 may send the information to the RRC layer 203 together with a request to transition from RRC_IDLE or RRC_INACTIVE to RRC_CONNETED. The feature combination may be a combination of Release 17 features. Specifically, the feature combination may include at least two of RedCap, SDT, CovEnh, and Slicing.

[0072] The information indicating the feature combination may indicate one or more network slices intended by the NAS layer 202. Each of the one or more intended network slices may be identified by an S-NSSAI. The intended network slices may be S-NSSAI(s) included in the Configured NSSAI or S-NSSAI(s) included in the Allowed NSSAI. Alternatively, the information indicating the feature combination may indicate one or more network slice groups intended by the NAS layer 202. Each of the one or more intended network slice groups may be identified by a slice group ID. Mapping of each network slice group to one or more network slices may be provided to UE1 (NAS layer 202) by a core network (e.g., AMF) via NAS signaling. Alternatively, the information regarding the first feature may indicate one or more network slice priority levels. Mapping between each slice priority level and one or more network slices may be provided to UE1 (NAS layer 202) by a core network (e.g., AMF) via NAS signaling.

[0073] In step 502, the AS layer 208 selects a random access resource from a set of random access resources associated with the feature combination indicated by the NAS layer 202. Specifically, the RRC layer 203 may indicate the feature combination to the MAC layer 206. The MAC layer 206 may select a random access resource from the set of random access resources associated with the feature combination indicated by the RRC layer 203. UE1 transmits a preamble on a random access resource selected from the resource set (or partition), thereby enabling RAN node 2 to early identify the feature combination selected, desired, or intended by UE1.

[0074] In step 503, the AS layer 208 transmits a random access preamble on the selected random access resource. Specifically, the MAC layer 206 requests the PHY layer 207 to transmit a preamble on the selected random access resource.

[0075] Figure 6 shows a specific example of the operation of UE1 described with reference to Figure 5. In step 601, the AS layer 208 of UE1 is in RRC_INACTIVE. Although not shown, if UE1 receives an RRC Release message including suspendConfig from RAN node 2 while in RRC_CONNETED, the RRC layer 203 indicates the suspension of the RRC connection to the upper layer (i.e., NAS layer 202) and enters RRC_INACTIVE. Therefore, the 5GMM mode of the NAS layer 202 is 5GMM-CONNECTED with RRC inactive indication.

[0076] In step 602, the AS layer 208 sends an MT-SDT indication to the NAS layer 202. For example, the AS layer 208 may send the MT-SDT indication to the NAS layer 202 in response to receiving a paging indicating or related to MT-SDT from the core network (e.g., AMF) via the RAN node 2. Alternatively, the AS layer 208 may send the MT-SDT indication to the NAS layer 202 in response to receiving a paging indicating or related to MT-SDT (i.e., RAN paging) from the RAN node 2. The RAN paging may be generated by the RAN node 2 and sent to the UE 1 in response to the RAN node 2 receiving data for a suspended DRB (or a corresponding QoS flow) from the core network (e.g., UPF). The paging and the RAN paging may include a flag indicating MT-SDT. Additionally or alternatively, the paging and RAN paging may include information about the DRB(s), PDU session(s), QoS flow(s), and / or one or more network slices (e.g., S-NSSAI(s)) that are the subject of the MT-SDT. Similar information may be included in the MT-SDT indication from the AS layer 208 to the NAS layer 202. Alternatively, the MT-SDT indication may be implicitly indicated by an indication requesting the resume of a suspended DRB (or corresponding QoS flow).

[0077] In step 603, the NAS layer 202 is triggered to make an access attempt by the MT-SDT indication. The access attempt is related to a specific network slice (e.g., Slice-X). In step 604, in response to the triggered access attempt, the NAS layer 202 determines a feature combination (e.g., SDT+Slicing). In step 605, the NAS layer 202 sends joint information indicating the feature combination to the AS layer 208. In step 606, the AS layer 208 determines a RACH resource for RACH preamble transmission from a set (or partition) of RACH resources associated with the feature combination indicated by the NAS layer 202. Specifically, the RRC layer 203 indicates the feature combination to the MAC layer 206. The MAC layer 206 determines a RACH resource for RACH preamble transmission from a set (or partition) of RACH resources associated with the feature combination indicated by the RRC layer 203. The joint information indicating the feature combination may be, for example, explicit information that MT-SDT should be performed (or should be performed) for a suspended DRB (or QoS flow), or may be implicit information that an RRC connection should be resumed (or should be resumed) for data transmission on the DRB (or QoS flow).

[0078] According to the operation of UE1 described with reference to Figure 5 and / or Figure 6, the NAS layer 202 can determine the feature combination, and the AS layer 208 can select the RACH resource associated with the feature combination determined by the NAS layer 202. This can therefore provide interaction between the NAS layer 202 and the AS layer 208 of UE1 for random access resource selection corresponding to the feature combination.

[0079] Note that in step 502 of Fig. 5 or step 606 of Fig. 6, if the set of random access resources associated with the feature combination is not configured (or is not available) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may notify the NAS layer 202 of a failure without transmitting the random access preamble. The failure cause sent by the AS layer 208 to the NAS layer 202 may be "other" or a newly defined value. Alternatively, the AS layer 208 may perform any of the fallback operations described in detail in the third or fourth embodiment below.

[0080] <Third embodiment> A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0081] Figure 7 shows an example of the operation of UE1 in a random access procedure. Steps 701 to 703 relate to random access resource selection. For example, UE1 may perform steps 701 to 703 instead of step 303 in Figure 3, step 405 in Figure 4, step 502 in Figure 5, or step 606 in Figure 6.

[0082] In step 701, UE1 (MAC layer 206) determines whether a first set of random access resources associated with a feature combination selected, desired, or intended by UE1 is configured (or available). Note that the RRC layer 203 may configure the MAC layer 206 with multiple resource sets (or resource partitions) including the first set. The RRC layer 203 receives a random access configuration from RAN node 2 via broadcast and configures the MAC layer 206 with the multiple resource sets (or resource partitions) indicated in the random access configuration.

[0083] Thus, a YES result in step 701 means that RAN node 2 provides in cell 21 a random access resource set (or resource partition) associated with the feature combination selected, desired or intended by UE1. In other words, a YES result in step 701 means that the feature combination selected, desired or intended by UE1 is supported (or available) in cell 21. In contrast, a NO result in step 701 means that RAN node 2 does not provide in cell 21 a random access resource set (or resource partition) associated with the feature combination selected, desired or intended by UE1. In other words, a NO result in step 701 means that the feature combination selected, desired or intended by UE1 is not supported (or available) in cell 21.

[0084] Note that UE1 (MAC layer 206) may select between a normal uplink (NUL) carrier and a supplementary uplink (SUL) carrier prior to random access resource selection. The SUL carrier may be configured as a complement of the NUL carrier. Typically, the SUL carrier uses a lower uplink frequency than the NUL carrier to complement the coverage of the NUL carrier. UE1 (MAC layer 206) may select one of the NUL and SUL uplink carriers based on downlink measurement results. For example, UE1 may operate similarly to the selection between the NUL and SUL carriers in 3GPP Release 15 and / or Release 16. If the downlink pathloss reference (RSRP) is lower than the RSRP threshold for uplink carrier selection (e.g., rsrp-ThresholdSSB-SUL), UE1 may select the SUL carrier for the random access procedure. Otherwise, UE1 may select the NUL carrier for the random access procedure.

[0085] The network (e.g., RAN node 2) may not necessarily support the same features or feature combinations on both the NUL and SUL carriers. Thus, in step 701, UE1 (MAC layer 206) may determine whether a first set of random access resources associated with a feature combination selected, desired, or intended by UE1 is available on the selected uplink carrier. In this case, a YES result at step 701 means that the feature combination selected, desired, or intended by UE1 is supported (or available) on the selected uplink carrier. A NO result at step 701 means that the feature combination selected, desired, or intended by UE1 is not supported (or available) on the selected uplink carrier.

[0086] If the answer is YES at step 701, UE 1 (MAC layer 206) selects a random access resource from the first set (step 702).

[0087] If the answer is NO in step 701, UE1 (MAC layer 206) selects random access resources from a second set of random access resources associated with a feature subset included in the selected feature combination (step 703). A feature subset may also be referred to as a feature subset, feature subcombination, or feature subcombination. A feature subset may include one or more features. For example, when the selected feature combination is SDT+Slicing, the feature subset may be SDT or Slicing. When the selected feature combination is RedCap+SDT+Slicing, the feature subset may be RedCap, RedCap+SDT, or RedCap+Slicing. A feature subset may include one or more features supported (or executable) by cell 21. UE1 may select a feature subset that should be prioritized, or may select a feature subset that is highly necessary (or important). For example, when a feature combination includes RedCap and one or more other features, UE1 may necessarily include RedCap in the feature subset.

[0088] In step 704, the MAC layer 206 of UE1 transmits a random access preamble using the selected random access resource, specifically, the MAC layer 206 of UE1 requests the PHY layer 207 to transmit a random access preamble (RACH preamble) on the selected RACH resource.

[0089] When performing the fallback operations of steps 703 and 704, the AS layer 208 of UE1 may notify the NAS layer 202 of a random access failure corresponding to the originally intended feature combination or a fallback to a feature subset. Additionally or alternatively, if the feature subset is not available in step 703, the AS layer 208 may notify the NAS layer 202 of a random access failure corresponding to the originally intended feature or feature combination. In this case, the AS layer 208 may notify the NAS layer 202 of a failure of the (most) prioritized feature in the feature combination. Alternatively, the AS layer 208 may notify the NAS layer 202 of a failure of a feature for which the AS layer 208 (e.g., MAC layer 206) is not permitted to determine whether or not the feature (function) needs to be executed or whether or not it can be executed.

[0090] According to the operation of UE1 described with reference to FIG. 7 , if the cell 21 does not provide a RACH resource set associated with a feature combination selected, desired, or intended by UE1, UE1 selects a RACH resource for random access to the cell 21 from among alternative RACH resource sets provided by the cell 21 that are associated with feature subsets included in the feature combination. This operation of UE1 allows the cell 21 or RAN node 2 to provide multiple RACH resource sets for only a subset of all possible feature combinations. Therefore, the cell 21 does not necessarily need to provide all RACH resource sets for all possible feature combinations. This can help reduce fragmentation of random access resources.

[0091] <Fourth embodiment> A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0092] Figure 8 shows an example of the operation of UE1 in a random access procedure. Steps 801 to 803 relate to random access resource selection. For example, UE1 may perform steps 801 to 803 instead of step 303 in Figure 3, step 405 in Figure 4, step 502 in Figure 5, or step 606 in Figure 6.

[0093] In step 801, UE1 (MAC layer 206) determines whether a first set of random access resources associated with a feature combination selected, desired, or intended by UE1 is configured (or available). Note that the RRC layer 203 may configure the MAC layer 206 with multiple resource sets (or resource partitions) including the first set. The RRC layer 203 receives a random access configuration from RAN node 2 via broadcast and configures the MAC layer 206 with the multiple resource sets (or resource partitions) indicated in the random access configuration.

[0094] Thus, a YES result in step 801 means that RAN node 2 provides in cell 21 a random access resource set (or resource partition) associated with the feature combination selected, desired or intended by UE1. In other words, a YES result in step 801 means that the feature combination selected, desired or intended by UE1 is supported (or available) in cell 21. In contrast, a NO result in step 801 means that RAN node 2 does not provide in cell 21 a random access resource set (or resource partition) associated with the feature combination selected, desired or intended by UE1. In other words, a NO result in step 801 means that the feature combination selected, desired or intended by UE1 is not supported (or available) in cell 21.

[0095] Note that UE1 (MAC layer 206) may select between the NUL carrier and the SUL carrier prior to random access resource selection. The SUL carrier may be configured as a complement of the NUL carrier. Typically, the SUL carrier uses a lower uplink frequency than the NUL carrier to complement the coverage of the NUL carrier. UE1 (MAC layer 206) may select one of the NUL and SUL uplink carriers based on downlink measurement results. For example, UE1 may operate similarly to the selection between the NUL and SUL carriers in 3GPP Release 15 and / or Release 16. If the RSRP of the downlink path loss metric is lower than the RSRP threshold for uplink carrier selection (e.g., rsrp-ThresholdSSB-SUL), UE1 may select the SUL carrier for the random access procedure. Otherwise, UE1 may select the NUL carrier for the random access procedure.

[0096] The network (e.g., RAN node 2) may not necessarily support the same features or feature combinations on both the NUL and SUL carriers. Thus, in step 801, UE1 (MAC layer 206) may determine whether a first set of random access resources associated with a feature combination selected, desired, or intended by UE1 is available on the selected uplink carrier. In this case, a YES result in step 801 means that the feature combination selected, desired, or intended by UE1 is supported (or available) on the selected uplink carrier. A NO result in step 801 means that the feature combination selected, desired, or intended by UE1 is not supported (or available) on the selected uplink carrier.

[0097] If the answer is YES in step 801, UE 1 (MAC layer 206) selects a random access resource from the first set (step 1102).

[0098] If the answer is NO in step 801, UE1 (MAC layer 206) selects random access resources from a second set of random access resources not associated with the feature combination (step 803). For example, UE1 may perform the random access resource selection in the same manner as in the random access procedure of 3GPP Release 15 and / or Release 16.

[0099] In step 804, the MAC layer 206 of UE1 transmits a random access preamble using the selected random access resource, specifically, the MAC layer 206 of UE1 requests the PHY layer 207 to transmit a random access preamble (RACH preamble) on the selected RACH resource.

[0100] When performing the fallback operations of steps 803 and 804, the AS layer 208 of UE1 may notify the NAS layer 202 of a failure of random access corresponding to the originally intended feature combination or a fallback to random access that does not take into account the feature combination.

[0101] According to the operation of UE1 described with reference to FIG. 8 , if the cell 21 does not provide a RACH resource set associated with the feature combination selected, desired, or intended by UE1, UE1 selects a RACH resource for random access to the cell 21 from among alternative RACH resource sets not associated with the feature combination. This operation of UE1 allows the cell 21 or RAN node 2 to provide multiple RACH resource sets for only a subset of all possible features and feature combinations. Thus, the cell 21 does not necessarily have to provide all RACH resource sets for all possible features and feature combinations. This can help reduce fragmentation of random access resources.

[0102] <Fifth embodiment> A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0103] This embodiment relates to handling of features and feature combinations selected, desired, or intended by UE1. Features can be divided into at least two types. In the first type, the MAC layer 206 of UE1 determines whether or not a feature needs to be executed (or whether or not the feature can be executed) based on information or conditions predetermined by itself. Additionally or alternatively, the MAC layer 206 may make the above determination based on information received from or specified by a higher layer (e.g., the RRC layer 203) of UE1. In this type, if the MAC layer 206 of UE1 determines that at least one feature of the selected, desired, or intended feature combination does not need to be executed (or cannot be executed), the MAC layer 206 may change the content of the feature combination (i.e., included features) to select RACH resources for the remaining features or feature combinations excluding the selected feature. In other words, the MAC layer 206 may select a feature subset excluding the feature that does not need to be executed (or cannot be executed). In this case, the MAC layer 206 may notify the RRC layer 203 of the determination result (for example, information on the feature combination to be executed, information on the removed feature).

[0104] In the second type, the MAC layer 206 of UE1 does not or should not determine whether the feature needs to be implemented (or whether the feature is executable). In this type, the RRC layer 203 of UE1 determines whether the feature needs to be implemented (or whether the feature is executable) and notifies the MAC layer 206 of the necessary information. The determination by the RRC layer 203 may be based on one or both of UE1's capabilities and predefined information held by the RRC layer 203. Additionally or alternatively, the RRC layer 203 may make the above determination based on information received or specified from a higher layer of UE1 (e.g., the NAS layer 202). The MAC layer 206 selects a RACH resource corresponding to the feature or a feature combination including the feature. If the MAC layer 206 determines that there is no RACH resource corresponding to the feature, it may report a RACH resource selection failure indication to the RRC layer 203. On the other hand, if the MAC layer 206 determines that there is no RACH resource corresponding to the feature combination including the feature, the MAC layer 206 may exclude one or more features corresponding to the first type from the feature combination and select a RACH resource corresponding to a feature subset including the feature of the second type and the remaining one or more features corresponding to the first type. Alternatively, the MAC layer 206 may select a RACH resource corresponding only to the feature of the second type. In other words, when it is necessary to select a feature subset from a feature combination, the MAC layer 206 may include one or more features of the second type (e.g., RedCap) that were included in the feature combination in the feature subset. The MAC layer 206 may then adjust the number of features in the feature subset depending on whether or not the feature of the first type that was included in the feature combination is included in the feature subset.

[0105] The feature combination selected, desired, or intended by UE1 may include only one of the above two types, or may include both of the two types. If the feature combination includes both types, the MAC layer 206 may preferentially consider the feature of the second type. For example, the MAC layer 206 may preferentially implement the feature of the second type. The MAC layer 206 may preferentially select RACH resources corresponding to the feature of the second type.

[0106] Sixth Embodiment A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0107] In this embodiment, UE1 considers during cell selection or reselection, or both, whether a candidate cell provides a separate set of random access resources for a feature or feature combination selected, desired, or intended by UE1. The feature may be any of the Release 17 features. The feature combination may be a combination of Release 17 features. The feature may be RedCap, SDT, CovEnh, or Slicing. The feature combination may include at least two of RedCap, SDT, CovEnh, and Slicing. Random access based on a Release 17 feature or feature combination enables UE1 to provide the network with an early indication of the Release 17 feature or feature combination via the random access resources to be used for preamble transmission.

[0108] UE1 (RRC layer 203) may consider a cell or frequency band that provides a dedicated preamble resource set for a feature or feature combination as having a higher priority for selecting a cell to camp on than a cell or frequency band that does not provide the dedicated preamble resource set. This operation allows UE1 to preferentially select a cell to camp on that provides a dedicated set of random access resources for a selected, desired, or intended feature or feature combination.

[0109] Specifically, in intra-frequency, i.e., intra-frequency-band, cell (re)selection, UE1 may operate as follows: if the highest ranked cell in terms of reception quality in a first frequency band does not provide the individual set, and the second highest ranked cell in the first frequency band provides the individual set, UE1 (RRC layer 203) selects the second highest ranked cell as the cell to camp on.

[0110] Additionally or alternatively, in inter-frequency, i.e., inter-frequency-band, cell (re)selection, UE1 may operate as follows: If the cell with the highest ranking in reception quality of a first frequency band does not provide the individual set and the cell with the highest ranking in reception quality of a second frequency band provides the individual set, UE1 (RRC layer 203) may select the cell with the highest ranking in the second frequency band as the cell to camp on. Alternatively, if the first frequency band does not support the provision of the individual set and the second frequency band supports the provision of the individual set, UE1 (RRC layer 203) may select the cell in the second frequency band as the cell to camp on. Note that the first and second frequency bands may have equal priority. Alternatively, the first frequency band may have a higher priority than the second frequency band.

[0111] Figure 9 shows an example of UE's operation during cell selection or reselection, or both. In step 901, UE (RRC layer 203) initiates a cell selection or cell reselection evaluation process. The cell selection process is initiated, for example, by the selection of a new PLMN or Stand-alone Non-Public Network (SNPN). The cell reselection evaluation process allows UE in RRC_IDLE or RRC_INACTIVE to select a more suitable cell. When UE is in Camped Normally state, UE attempts to detect, synchronize, and monitor intra-frequency, inter-frequency, and inter-RAT cells indicated by its serving cell (e.g., cell 21).

[0112] In step 902, UE1 (RRC layer 203) selects or reselects a cell to camp on from one or more candidate cells, taking into account whether the candidate cells provide a dedicated set of random access resources for the feature or feature combination. As described above, UE1 (RRC layer 203) may prioritize a cell or frequency band that provides a dedicated preamble resource set for the feature or feature combination over a cell or frequency band that does not provide the dedicated preamble resource set for selecting a cell to camp on. In step 903, UE1 camps on the selected or reselected cell. Note that UE1 may receive system information (e.g., SIB1) broadcast by a candidate cell for cell (re)selection and determine whether the candidate cell provides a dedicated set of random access resources for the feature or feature combination based on the received system information. Additionally or alternatively, system information (e.g., SIB1) broadcast by the current cell (serving cell) may indicate whether neighboring cells provide such a set, and UE1 may make the determination based on this information.

[0113] According to the cell selection or reselection described in this embodiment, the availability of random access based on Release 17 features or feature combinations is taken into consideration (or prioritized) for cell selection or reselection, so that UE1 can preferentially select a cell that supports random access based on Release 17 features or feature combinations in cell selection and cell reselection.

[0114] As described in the fifth embodiment, the feature combination selected, desired, or intended by UE1 may include only one of the above two types or both of the two types. If the feature combination includes both types, UE1 (RRC layer 203) may preferentially consider the second type of feature in cell selection or reselection. For example, the RRC layer 203 may consider a cell or frequency band in which the second type of feature (or feature subset) is available as a higher priority for selecting a cell to camp on than a cell or frequency band in which the second type of feature (or feature subset) is not available. According to this operation, UE1 can preferentially select a cell in which the second type of feature (or feature subset) is available as a cell to camp on. Alternatively, the RRC layer 203 may consider a cell or frequency band that provides a dedicated preamble resource set for the second type of feature (or feature subset) as a higher priority for selecting a cell to camp on than a cell or frequency band that does not provide the second type of feature. According to this operation, UE1 can preferentially select a cell that provides a dedicated preamble resource set for the second type of feature (or feature subset) as a cell to camp on.

[0115] Seventh Embodiment A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Fig. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Fig. 2.

[0116] The 3GPP RAN Working Group is considering enhancements to cell selection and reselection for slicing. This function is also scheduled to be introduced in 3GPP Release 17 (see, for example, Non-Patent Documents 5-8). This function is also called slice-based (or slice-group-based) cell (re)selection. This embodiment provides a solution for integrating cell (re)selection that prioritizes random access availability based on the Release 17 feature or feature combination described in the fifth embodiment with slice-based (or slice-group-based) cell (re)selection.

[0117] In this embodiment, UE1 (RRC layer 203) considers a cell that supports the intended network slice and provides a separate set of random access resources for a Release 17 feature or feature combination as having a higher priority for selecting a cell to camp on than a cell that does not support the network slice or does not provide the separate set. The intended network slice is the network slice intended by UE1's NAS layer 202. The intended network slice may be identified by an S-NSSAI. The intended network slice may be an S-NSSAI included in the Configured NSSAI or an S-NSSAI included in the Allowed NSSAI. The NAS layer 202 may indicate the intended network slice group to the RRC layer 203. The intended network slice group may be identified by a slice group ID. The mapping of the network slice group to one or more network slices may be provided to UE1 (NAS layer 202) by the core network (e.g., AMF) via NAS signaling. Alternatively, the NAS layer 202 may indicate the intended network slice priority level to the RRC layer 203. The mapping between slice priority levels and one or more network slices may be provided to UE 1 (NAS layer 202) by the core network (e.g., AMF) via NAS signaling.

[0118] In one implementation, the AS layer 208 may select the most suitable cell through a slice-based (or slice-group-based) cell (re)selection process, followed by a cell (re)selection process to prioritize random access availability based on a Release 17 feature or feature combination, as may be done, for example, as shown in FIG.

[0119] In step 1001, the AS layer 208 performs a slice-based (or slice-group-based) cell (re)selection process. Specifically, the RRC layer 203 selects a first candidate cell based on the network slice or network slice group intended by the NAS layer 202. As described above, the intended network slice priority level may be considered instead of the intended network slice group.

[0120] The selection of the first cell by the AS layer 208 may be performed, for example, as follows. · First step: Sort the slices in order of priority, starting with the slice with the highest priority. · Second step: Select slices from the sorted slice list in order of priority. Third step: For the selected slice, assign priorities to frequencies or frequency bands. The priorities of frequencies or frequency bands are set by the network (e.g., RAN node 2 or AMF). Step 4: Perform downlink measurements from the highest priority frequency bands, similar to those in Release 15 and Release 16. Step 5: If the highest ranked cell has suitable radio quality and supports the slice selected in step 2, select this cell as the first cell and exit the sequence. Step 6: If there are remaining frequencies, go back to step 4. · Step 7: If the end of the slice list has not been reached, go back to step 2. Step 8: Legacy cell reselection, i.e., cell reselection similar to that in Release 15 and Release 16.

[0121] Subsequently, in step 1002, the RRC layer 203 performs a cell (re)selection process to prioritize random access availability based on a Release 17 feature or feature combination. If the first cell is selected according to the sequence described in the immediately preceding paragraph, the RRC layer 203 may perform step 1002 after completing the sequence in step 5.

[0122] Specifically, the RRC layer 203 may (re)select as a cell to camp on a second candidate cell that is in the same frequency band as the first candidate cell selected in step 1001, satisfies a predetermined radio quality criterion, and provides a distinct set of random access resources for the feature or feature combination. In one example, the predetermined radio quality criterion is that the downlink quality metric (e.g., RSRP, RSRQ, Srxlev, Squal) of the first candidate cell minus the downlink quality metric of the second candidate cell is less than (or equal to or less than) a threshold. In other words, the predetermined radio quality criterion is that the downlink quality metric of the second candidate cell is greater than (or equal to or greater than) the downlink quality metric of the first candidate cell minus a threshold. The threshold may be predetermined or configured by the network (e.g., RAN node 2).

[0123] In other implementations, the AS layer 208 may perform a cell (re)selection process to prioritize random access availability based on a Release 17 feature or feature combination simultaneously (or in parallel) with the slice-based (or slice-group-based) cell (re)selection process. This may occur, for example, during the fifth step of the slice-based (or slice-group-based) cell (re)selection sequence described above. For example, if there are multiple candidate cells with the highest priority slices available, the AS layer 208 (RRC layer 203) may prioritize candidate cells that offer distinct sets of random access resources for the feature or feature combination.

[0124] In yet another implementation, the AS layer 208 may select a suitable cell through a cell (re)selection process that prioritizes the availability of random access based on a Release 17 feature or a combination of features, followed by slice-based (or slice-group-based) cell (re)selection. For example, the AS layer 208 may preferentially select a cell that has available random access based on a Release 17 feature or a combination of features as a candidate cell, followed by slice-based (or slice-group-based) cell (re)selection.

[0125] As described in the fifth embodiment, the feature combination selected, desired, or intended by UE1 may include only one of the above two types or both of the two types. If the feature combination includes both types, UE1 (RRC layer 203) may preferentially consider the second type of feature in cell selection or reselection. For example, the RRC layer 203 may consider a cell or frequency band in which the second type of feature (or feature subset) is available as a higher priority for selecting a cell to camp on than a cell or frequency band in which the second type of feature (or feature subset) is not available. According to this operation, UE1 can preferentially select a cell in which the second type of feature (or feature subset) is available as a cell to camp on. Alternatively, the RRC layer 203 may consider a cell or frequency band that provides a dedicated preamble resource set for the second type of feature (or feature subset) as a higher priority for selecting a cell to camp on than a cell or frequency band that does not provide the second type of feature. According to this operation, UE1 can preferentially select a cell that provides a dedicated preamble resource set for the second type of feature (or feature subset) as a cell to camp on.

[0126] Next, exemplary configurations of a UE 1 and a RAN node 2 according to the above-described embodiments will be described below. FIG. 11 is a block diagram illustrating an exemplary configuration of a UE 1. A radio frequency (RF) transceiver 1101 performs analog RF signal processing for communication with a RAN node. The RF transceiver 1101 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1101 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1101 is coupled to an antenna array 1102 and a baseband processor 1103. The RF transceiver 1101 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1103, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1102. The RF transceiver 1101 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1102 and provides the baseband receive signal to the baseband processor 1103. The RF transceiver 1101 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0127] The baseband processor 1103 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (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 includes communication management for 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).

[0128] For example, the digital baseband signal processing by the baseband processor 1103 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Also, the control plane processing by the baseband processor 1103 may include processing of a Non-Access Stratum (NAS) protocol, a Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0129] The baseband processor 1103 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0130] The baseband processor 1103 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 1104, which will be described later.

[0131] The application processor 1104 is also referred to as a CPU, an MPU, a microprocessor, or a processor core. The application processor 1104 may include multiple processors (multiple processor cores). The application processor 1104 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1106 or a memory not shown, thereby realizing various functions of the UE1.

[0132] In some implementations, the baseband processor 1103 and the application processor 1104 may be integrated on a single chip, as indicated by the dashed line (1105) in Figure 11. In other words, the baseband processor 1103 and the application processor 1104 may be implemented as a single System on Chip (SoC) device 1105. An SoC device is sometimes called a system Large Scale Integration (LSI) or a chipset.

[0133] The memory 1106 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1106 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 1106 may include an external memory device accessible from the baseband processor 1103, the application processor 1104, and the SoC 1105. The memory 1106 may also include an internal memory device integrated within the baseband processor 1103, the application processor 1104, or the SoC 1105. Furthermore, the memory 1106 may include memory within a universal integrated circuit card (UICC).

[0134] The memory 1106 may store one or more software modules (computer programs) 1107 including instructions and data for performing the processes described in the above embodiments by the UE 1. In some implementations, the baseband processor 1103 or the application processor 1104 may be configured to read and execute the software modules 1107 from the memory 1106 to perform the processes by the UE 1 described in the above embodiments with reference to the drawings.

[0135] In addition, the control plane processing and operations performed by UE1 described in the above embodiment can be realized by elements other than the RF transceiver 1101 and the antenna array 1102, namely, at least one of the baseband processor 1103 and the application processor 1104, and the memory 1106 storing the software module 1107.

[0136] FIG. 12 is a block diagram showing an example configuration of a RAN node 2 according to the above embodiment. Referring to FIG. 12, the RAN node 2 includes a radio frequency transceiver 1201, a network interface 1203, a processor 1204, and a memory 1205. The RF transceiver 1201 performs analog RF signal processing for communicating with UEs, including UE1. The RF transceiver 1201 may include multiple transceivers. The RF transceiver 1201 is coupled to an antenna array 1202 and the processor 1204. The RF transceiver 1201 receives modulation symbol data from the processor 1204, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1202. The RF transceiver 1201 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1202 and provides the baseband receive signal to the processor 1204. The RF transceiver 1201 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0137] The network interface 1203 is used to communicate with network nodes (e.g., SN2, and control and forwarding nodes of the core network). The network interface 1203 may include, for example, a network interface card (NIC) that complies with the IEEE 802.3 series.

[0138] The processor 1204 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1204 may include multiple processors. For example, the processor 1204 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. The processor 1204 may include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0139] The memory 1205 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1205 may include storage located remotely from the processor 1204. In this case, the processor 1204 may access the memory 1205 via the network interface 1203 or an I / O interface (not shown).

[0140] The memory 1205 may store one or more software modules (computer programs) 1206 including instructions and data for performing the processing by the RAN node 2 described in the above embodiments. In some implementations, the processor 1204 may be configured to read and execute the software modules 1206 from the memory 1205 to perform the processing by the RAN node 2 described in the above embodiments.

[0141] Note that if the RAN node 2 is a CU (e.g., gNB-CU) or a CU-CP (e.g., gNB-CU-CP), the RAN node 2 may not include the RF transceiver 1201 (and the antenna array 1202).

[0142] As described with reference to FIGS. 11 and 12 , each of the processors included in the UE 1 and the RAN node 2 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 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.

[0143] <Other Embodiments> In the above-described embodiment, the "feature" may be a feature newly introduced in a future 3GPP Release 18 or later. Similarly, in the above-described embodiment, the "feature combination" may include a feature newly introduced in a future 3GPP Release 18 or later. For example, in addition to the Mobile Originated (MO) SDT introduced in Release 17, Mobile Terminated (MT) SDT is planned to be introduced in 3GPP Release 18. In one implementation, the feature MT-SDT may be distinguished from the feature MO-SDT, and a separate RACH resource set (or partition, or pool) may be configured for the feature MT-SDT. In this case, the feature combination may include MT-SDT. The RAN node 2 may inform the UE 1 via a broadcast (e.g., SIB) or dedicated RRC signaling whether the MO-SDT and MT-SDT are distinguished in the RACH resource partition. Specifically, the random access configuration (e.g., RACH-Config) sent from RAN node 2 to UE1 may include a one-bit flag (e.g., "mt-SDT") as an optional element. If the random access configuration includes this flag, UE1 may use the RACH resource set for the feature (MO-)SDT for MT-SDT. On the other hand, if the random access configuration does not include this flag, UE1 checks whether a separate RACH resource set (or partition, or pool) is configured for MT-SDT, and if so, uses the separate RACH resource set for MT-SDT. If the random access configuration does not include this flag and a separate RACH resource set for MT-SDT is not configured, UE1 may understand that MT-SDT is not supported. In this case, if UE1 triggers MT-SDT, UE1 may use the RACH resource set for the feature (MO-)SDT for MT-SDT, or may use the same RACH resource set for MT-SDT as in Release 15 and / or Release 16.

[0144] In the above-described embodiment, if the configuration (e.g., random access configuration) received via RRC signaling (e.g., SIB) includes configuration, information, or fields related to features (e.g., Release 17 features) that UE1 does not support, UE1 may operate not to ignore the value (or code point) of the configuration, information, or field.

[0145] For example, UE1 may determine the size of the RACH resource set (or partition) for a desired feature or feature combination based on the value of the first ra-PreambleStartIndex field for that feature or feature combination and the value of the second ra-PreambleStartIndex field for another feature or feature combination that immediately follows it. In this case, UE1 must not ignore the value of the second ra-PreambleStartIndex field, regardless of whether UE1 supports the feature or feature combination associated with the second ra-PreambleStartIndex field.

[0146] In some of the above-described embodiments, for a specific feature or a feature combination including the specific feature, UE1 may perform an operation (or process) different from that in the above-described embodiments. For example, with respect to uplink carrier selection, for a specific feature (e.g., RedCap) or a feature combination including the specific feature, the uplink carrier (e.g., NUL carrier) to be selected may be predetermined (or specified in a specification). This is useful for fully utilizing the functionality of the feature or taking into account limitations in the functionality of the feature.

[0147] In some of the above-described embodiments, for a specific feature or a feature combination including the specific feature, UE1 may perform an operation (or process) different from that in the above-described embodiments. For example, for a specific feature (e.g., Coverage Enhancement), UE1 may determine whether the feature is necessary (or whether to execute the feature) after selecting an uplink carrier. This is useful when the function of the feature depends on the result of uplink carrier selection.

[0148] Furthermore, 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.

[0149] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0150] (Appendix 1) at least one memory; at least one processor coupled to the at least one memory and configured to provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality; the NAS layer function is configured to pass information about the first characteristic to the AS layer function; The AS layer function determining a feature combination including the first feature and one or more other features derived from the information; selecting a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function; transmitting a random access preamble on the selected random access resource; It is configured as follows: Wireless terminal. (Appendix 2) The first feature is slicing, The one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh); 1. A wireless terminal as defined in claim 1. (Appendix 3) The information regarding the first feature indicates one or more network slices, one or more network slice groups, or one or more network slice priority levels intended by the NAS layer function, 3. A wireless terminal according to claim 1 or 2. (Appendix 4) The information regarding the first feature indicates one or more Single Network Slice Selection Assistance Information (S-NSSAI) to indicate the intended one or more network slices. 10. A wireless terminal as defined in claim 3. (Appendix 5) The AS layer function is configured to not transmit a random access preamble if the first set is not available in the serving cell and to notify the NAS layer of the failure. 5. The wireless terminal according to any one of Supplementary notes 1 to 4. (Appendix 6) The AS layer function if the first set is not available in the serving cell, selecting a random access resource from a second set of random access resources associated with a feature subset included in the feature combination; transmitting a random access preamble on a random access resource selected from the second set; It is configured as follows: 5. The wireless terminal according to any one of Supplementary notes 1 to 4. (Appendix 7) The AS layer function If the first set is not available in the serving cell, selecting a random access resource from a third set of random access resources not associated with the feature combination; transmitting a random access preamble on a random access resource selected from the third set; It is configured as follows: 5. The wireless terminal according to any one of Supplementary notes 1 to 4. (Appendix 8) Providing Non-Access Stratum (NAS) layer functions and Access Stratum (AS) layer functions; the NAS layer function passing information about the first characteristic to the AS layer function; said AS layer function determining a feature combination comprising said first feature and one or more other features derived from said information; the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function; and the AS layer function transmitting a random access preamble on the selected random access resource; Equipped with A method performed by a wireless terminal. (Appendix 9) A program for causing a computer to perform a method for a wireless terminal, comprising: The method comprises: Providing Non-Access Stratum (NAS) layer functions and Access Stratum (AS) layer functions; the NAS layer function passing information about the first characteristic to the AS layer function; said AS layer function determining a feature combination comprising said first feature and one or more other features derived from said information; the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function; the AS layer function transmitting a random access preamble on the selected random access resource; Equipped with program. (Appendix 10) at least one memory; at least one processor coupled to the at least one memory and configured to provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality; the NAS layer function is configured to pass information indicating a feature combination to the AS layer function; The AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function; transmitting a random access preamble on the selected random access resource; It is configured as follows: Wireless terminal. (Appendix 11) The feature combination includes Slicing and one or more other features. 11. The wireless terminal of claim 10. (Appendix 12) The one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh); 12. The wireless terminal of claim 11. (Appendix 13) The one or more other features include at least Small Data Transmission (SDT); 13. The wireless terminal of claim 11 or 12. (Appendix 14) The information indicating the feature combination indicates one or more network slices intended by the NAS layer function. 14. The wireless terminal according to any one of Supplementary notes 10 to 13. (Appendix 15) The information indicating the feature combination includes one or more Single Network Slice Selection Assistance Information (S-NSSAI) to indicate the intended one or more network slices. 15. The wireless terminal of claim 14. (Appendix 16) The AS layer function is configured to not transmit a random access preamble if the first set is not available in the serving cell and to notify the NAS layer of the failure. 16. A wireless terminal according to any one of Supplementary notes 10 to 15. (Appendix 17) The AS layer function if the first set is not available in the serving cell, selecting a random access resource from a second set of random access resources associated with a feature subset included in the feature combination; transmitting a random access preamble on a random access resource selected from the second set; It is configured as follows: 16. A wireless terminal according to any one of Supplementary notes 10 to 15. (Appendix 18) The AS layer function If the first set is not available in the serving cell, selecting a random access resource from a third set of random access resources not associated with the feature combination; transmitting a random access preamble on a random access resource selected from the third set; It is configured as follows: 16. A wireless terminal according to any one of Supplementary notes 10 to 15. (Appendix 19) Providing Non-Access Stratum (NAS) layer functions and Access Stratum (AS) layer functions; the NAS layer function passing information indicating the feature combination to the AS layer function; the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function; and the AS layer function transmitting a random access preamble on the selected random access resource; Equipped with A method performed by a wireless terminal. (Appendix 20) A program for causing a computer to perform a method for a wireless terminal, comprising: The method comprises: Providing Non-Access Stratum (NAS) layer functions and Access Stratum (AS) layer functions; the NAS layer function passing information indicating the feature combination to the AS layer function; the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function; and the AS layer function transmitting a random access preamble on the selected random access resource; Equipped with program. (Appendix 21) at least one memory; at least one processor coupled to the at least one memory; the at least one processor is configured, when selecting or reselecting a cell to camp on from one or more candidate cells, to consider whether the candidate cells provide a distinct set of random access resources for the selected, desired, or intended feature or feature combination; Wireless terminal. (Appendix 22) the at least one processor is configured to consider a cell or frequency band that offers the distinct set as having a higher priority for selecting a cell to camp on than a cell or frequency band that does not offer the distinct set. 22. The wireless terminal of claim 21. (Appendix 23) the at least one processor is configured to, if a cell highest ranked in reception quality for a first frequency band does not provide the individual set and a cell second highest ranked in the first frequency band provides the individual set, select the cell second highest ranked as the cell to camp on. 23. The wireless terminal of claim 21 or 22. (Appendix 24) the at least one processor is configured to, if a cell with a highest ranking in reception quality for a first frequency band does not provide the individual set and a cell with a highest ranking in reception quality for a second frequency band provides the individual set, select the cell with the highest ranking in the second frequency band as the cell to camp on. 23. The wireless terminal of claim 21 or 22. (Appendix 25) the at least one processor is configured to, if a first frequency band does not support providing the individual set and a second frequency band supports providing the individual set, select a cell of the second frequency band as the cell to camp on. 23. The wireless terminal of claim 21 or 22. (Appendix 26) The at least one processor is configured to consider a cell that supports the intended network slice, network slice group, or network slice priority level and provides the individual set as having a higher priority for selecting a cell to camp on than a cell that does not support the intended network slice or network slice group or does not provide the individual set. A wireless terminal according to any one of Supplementary notes 21 to 25. (Appendix 27) The at least one processor: Selecting a first candidate cell based on an intended network slice or network slice group; selecting a second candidate cell that is in the same frequency band as the first candidate cell, satisfies a predetermined wireless quality criterion, and provides the individual set as the cell to camp on; It is configured as follows: A wireless terminal according to any one of Supplementary notes 21 to 26. (Appendix 28) The feature is Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing; The feature combination includes at least two of RedCap, SDT, CovEnh, and Slicing; A wireless terminal according to any one of Supplementary notes 21 to 27. (Appendix 29) When selecting or reselecting a cell to camp on from one or more candidate cells, taking into account whether the candidate cells provide a distinct set of random access resources for the selected, desired, or intended feature or feature combination; A method performed by a wireless terminal. (Appendix 30) A program for causing a computer to perform a method for a wireless terminal, comprising: The method comprises, when selecting or reselecting a cell to camp on from one or more candidate cells, considering whether the candidate cells provide a distinct set of random access resources for a selected, desired, or intended feature or feature combination. program.

[0151] This application claims priority based on Japanese Patent Application No. 2021-171921, filed on October 20, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0152] 1 UE 2. RAN nodes 21, 31 cells 1103 Baseband Processor 1104 Application Processor 1106 Memory 1107 Modules 1204 processor 1205 memory 1206 Modules

Claims

1. means for receiving information about a slice from a core network; means for receiving system information including a random access configuration from a radio access network node; means for determining whether a first set of random access resources associated with a feature or a feature combination selected, desired, or intended by a wireless terminal from among any one feature of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; means for selecting a first random access resource from the first set if the first set is available, and transmitting a random access preamble using the selected first random access resource; means for selecting a second random access resource from a second set of random access resources not associated with the feature or the combination of features if the first set is unavailable, and for transmitting a random access preamble using the selected second random access resource; A wireless terminal comprising:

2. The receiving means receives information about the slice from the core network at a Non-Access Stratum (NAS) layer; Information about the slice is provided from the NAS layer to an Access Stratum (AS) layer; determining, in the AS layer, whether a first set of random access resources associated with a feature or a feature combination selected, desired, or intended by a wireless terminal from among any one feature of the RedCap, the SDT, the CovEnh, or the Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; The wireless terminal of claim 1 .

3. and determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison of a downlink path loss metric RSRP and rsrp-ThresholdSSB-SUL before determining whether the first set is available. The wireless terminal of claim 1 .

4. receiving information about the slice from a core network; receiving system information from a radio access network node, the system information including a random access configuration; determining whether a first set of random access resources associated with a feature or feature combination selected, desired, or intended by a wireless terminal from among any one feature of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; If the first set is available, selecting a first random access resource from the first set and transmitting a random access preamble using the selected first random access resource; and if the first set is unavailable, selecting a second random access resource from a second set of random access resources not associated with the feature or the feature combination, and transmitting a random access preamble using the selected second random access resource; A method performed by a wireless terminal, comprising:

5. Receiving information about the slice includes receiving information about the slice from the core network at a Non-Access Stratum (NAS) layer; Information about the slice is provided from the NAS layer to an Access Stratum (AS) layer; determining, in the AS layer, whether a first set of random access resources associated with a feature or a feature combination selected, desired, or intended by a wireless terminal from among any one feature of the RedCap, the SDT, the CovEnh, or the Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; The method of claim 4.

6. and determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison of a downlink path loss metric RSRP and rsrp-ThresholdSSB-SUL before determining whether the first set is available. The method of claim 4.

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