Wireless terminal and method

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, particularly to random access and cell (re)selection.

Background Art

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark)) Radio Access Network (RAN) Working Group is currently considering supporting additional random access resource partitioning. This function is planned 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 enables a wireless terminal (e.g., User Equipment (UE)) to inform a wireless access network node (e.g., gNB, eNB) of information by the resources used in random access preamble transmission.

[0003] In this specification, random access resources mean 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 occasions are also called RACH occasions (ROs), and random access preambles are also called RACH preambles. A single RACH occasion is a time and frequency resource for RACH preamble transmission. According to the current 3GPP Release 15 and Release 16, a single RACH occasion can have up to 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 is used: - 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 enable the network (e.g., gNB) to identify features early, additional RACH partitioning has been considered for several 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 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 called functional features.

[0006] RedCap indication in RACH is used to show 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] In RACH, the SDT indicator is used to show the SDT to the network and request a larger third RACH message (MSG3) size. Alternatively, the SDT indicator is used to indicate a larger MSGA size (size of the data portion of the MSGA) in the case of a two-step RA.

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

[0009] Slicing indication in RACH is used to show high-priority slices in the network and to achieve slice isolation for RACH as well. Slicing indication may be binary information to distinguish between prioritized and non-prioritized network slices. Alternatively, Slicing indication may show multi-level slice priority, selected or intended network slices, or selected or intended network slice groups, but this would lead to a further increase in the number of partitions.

[0010] Furthermore, the 3GPP RAN Working Group is considering enhancements to cell selection and re-selection for slicing. This functionality is also scheduled to be introduced in 3GPP Release 17 (see, for example, Non-Patent Documents 5-8). This functionality is also called slice-based (or slice-group-based) cell (re)selection. It allows the UE's Access Stratum (AS) layer to preferentially select or re-select cells that support an intended network slice (or network slice group). The intended network slice (or network slice group) is indicated to the UE's AS layer by the UE's Non-Access Stratum (NAS) layer. [Prior art documents] [Non-patent literature]

[0011]

Non-licensed literature 1

Non-licensed Document 2

Non-licensed Document 4

Non-licensed Document 5

Non-licensed Document 6

[0012] The inventors of this case investigated random access resource partitioning for Release 17 features and feature combinations, and identified various problems.

[0013] One of these challenges concerns the interaction between the UE's NAS layer and the UE's AS layer in the selection of feature combinations. For example, as mentioned above, the new Release 17 feature currently envisioned for additional RACH partitioning includes "Slicing". Whether or not Slicing representation in RACH is required is thought to depend on the network slice (or slice group) intended by the UE's NAS layer. On the other hand, the selection of RACH resources based on feature combinations is performed by the UE's AS layer. In such cases, it is unclear how the interaction between the UE's NAS layer and the UE's AS layer occurs for the determination of feature combinations or for the selection of random access resources corresponding to feature combinations.

[0014] Another of these challenges relates to cell selection or re-selection, or both. In the inventor's considerations, in cell selection and re-selection, it may be preferable for the UE to be able 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 enables the UE to provide the network with an early representation of Release 17 features or feature combinations via random access resources used for preamble transmission. However, whether the availability of random access based on features or feature combinations should be considered (or preferred) for cell selection or re-selection has not yet been discussed.

[0015] One of the objectives that the embodiments disclosed herein seek to achieve is to provide apparatus, methods, and programs that contribute to solving at least one of several problems relating to random access resource partitioning, including the problems described above. It should be noted that this objective is only one of several objectives that the embodiments disclosed herein seek to achieve. Other objectives or problems and novel features will be revealed by the description herein or by the accompanying drawings.

Means for Solving the Problem

[0016] In a first aspect, the 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 derived from the information and one or more other features. 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 perform a random access preamble transmission using the selected random access resource.

[0017] In a second aspect, the method performed by the wireless terminal includes the following steps: (a) Providing a NAS layer function and an AS layer function, (b) The NAS layer function passing information regarding a first feature to the AS layer function, (c) The AS layer function determining a feature combination including the first feature derived from the information and one or more other features, (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 performing a random access preamble transmission using the selected random access resource.

[0018] In a third aspect, the 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 NAS layer functions and AS layer functions. 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 using the selected random access resource.

[0019] In a fourth aspect, the method performed by the wireless terminal includes the following steps: (a) Providing NAS layer functions and AS layer functions, (b) The NAS layer function passing information indicating a 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 performing a random access preamble transmission using the selected random access resource.

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

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

[0022] The seventh aspect is directed to a program, which, when loaded into a computer, includes a set of instructions (software code) for causing the computer to perform the methods described in the second, fourth, or sixth aspects above. [Effects of the Invention]

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

[0024] [Figure 1] This figure shows an example configuration of a wireless communication system according to the embodiment. [Figure 2] This figure shows an example of a protocol stack for the control plane of a wireless terminal according to the embodiment. [Figure 3] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 4] This is a sequence diagram showing an example of the operation of a wireless terminal according to the embodiment. [Figure 5] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 6] This is a sequence diagram showing an example of the operation of a wireless terminal according to the embodiment. [Figure 7] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 8] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 9]This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 10] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 11] This is a block diagram showing an example configuration of a wireless terminal according to the embodiment. [Figure 12] This block diagram shows an example configuration of a wireless access network node according to the embodiment. [Modes for carrying out the invention]

[0025] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numeral, and redundant explanations are omitted where necessary for clarity.

[0026] The multiple embodiments described below can be implemented independently or in combination as appropriate. These multiple embodiments have novel features that differ from each other. Therefore, these multiple embodiments contribute to solving different objectives or problems and contribute to producing different effects.

[0027] The following embodiments are described primarily with reference to 3GPP fifth-generation mobile communication systems (5G systems). However, these embodiments may also be applicable to other wireless communication systems.

[0028] As used herein, depending on the context, “(if)” may be interpreted as meaning “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 interpreted as having the same meaning depending on the context.

[0029] First, the configuration and operation of several network elements common to multiple embodiments will be described. Figure 1 shows 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 (ie, UE) 1, a wireless access network (RAN) node (e.g., gNB) 2, and a RAN node 3 (e.g., gNB). Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a running software instance on dedicated hardware, or as an instantiated virtualization function on an application platform.

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

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

[0032] RAN node 2 transmits signals containing System Information (SI) 101 and other signals into cell 21. System Information 101 includes a Master Information Block (MIB) and many System Information Blocks (SIBs). System Information 101 is divided into Minimum SI and Other SI. Minimum SI is always broadcast periodically and contains basic information necessary for initial access and information necessary to obtain 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), while Other SI includes SIB type 2 (SIB2) and later SIB types. Each SIB included in Other SI is either broadcast periodically at all times, broadcast on demand based on requests from UEs that are RRC_IDLE or RRC_INACTIVE, or sent to UEs that are RRC_CONNECTED via dedicated RRC signaling. Similarly, RAN node 3 transmits signals containing system information 102 and other signals into cell 21. If RAN node 2 or 3 is in a C-RAN configuration, a DU (e.g., gNB-DU) may generate at least some of the system information (e.g., MIB, SIB1). The DU may transmit the generated system information directly to UE1, or to a CU (e.g., gNB-CU) so that the CU can transmit it to UE1 (via the DU).

[0033] In the example in Figure 1, UE1 selects or re-selects cell 21 of RAN node 2 and camps on to cell 21. In other words, cell 21 is UE1's serving cell. Cell 31, on the other hand, is a neighboring cell of UE1's serving cell 21. Cells 21 and 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 in different frequency bands.

[0035] Figure 2 shows an example of the control plane protocol stack for UE1. The UE1 control plane protocol stack 200 includes the Application (APP) layer 201, the Non-Access Stratum (NAS) layer 202, and the Access Stratum (AS) layer 208. The AS layer 208 includes the RRC layer 203, the PDCP layer 204, the RLC layer 205, the MAC layer 206, and the PHY layer 207.

[0036] NAS layer 202 utilizes data communication and radio interface management on the radio interface provided by 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 is executed between UE1 and the Access and Mobility Management Function (AMF) in 5GC and is used for UE registration, mobility, and the transport of 5GSM protocol messages. The 5GSM protocol is executed via the AMF between UE1 and the Session Management Function (SMF) in 5GC and supports the management of PDU session connectivity.

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

[0038] AS layer 208 initiates an RRC connection establishment procedure or an RRC connection resumption procedure, either at the request of NAS layer 202 or spontaneously. For example, upon receiving a PDU session establishment request from a higher layer (i.e., application layer 201), NAS layer 202, if the 5GS mobility management (5GMM) mode is 5GMM-IDLE, initiates a registration procedure or a service request procedure to transition to 5GMM-CONNECTED mode and attempts to send an initial NAS message (e.g., registration request message or service request message) to the AMF. The initial NAS message from NAS layer 202 triggers 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, NAS layer 202 attempts to send a NAS message (e.g., PDU SESSION ESTABLISHMENT REQUEST message, UL NAS TRANSPORT message, PDU SESSION MODIFICATION REQUEST, or service request message) that depends 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", NAS layer 202 requests AS layer 208 to transition to RRC_CONNETED (or resumption of the RRC connection) in order to send the uplink user data packet (i.e., Mobile Originated (MO) data).

[0039] In response to receiving an initial NAS message or a request to transition to RRC_CONNETED, RRC layer 203 requests or triggers 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, RRC layer 203 may perform one or more access barring checks. If the access barring checks pass, RRC layer 203 may request 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). RRC layer 203 may perform barring checks for one or more of these access barring techniques.

[0040] MAC layer 206 receives a trigger for a random access procedure from RRC layer 203 based on events such as the re-establishment and reopening of the RRC connection, and initiates the random access procedure accordingly. 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, MAC layer 206 selects one RACH resource from a partitioned set of 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. A single RACH occasion is the time and frequency resource for RACH preamble transmission. According to the current 3GPP Release 15 and Release 16, a single RACH occasion has 64 RACH preambles available for transmission. The set of RACH resources can also be called a pool or partition of RACH resources.

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

[0043] MAC layer 206 may follow the RACH partitioning of 3GPP Release 16. With 3GPP Release 16 RACH partitioning, the UE can inform the gNB of the following information depending on which RACH preamble is used: - 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] In addition, MAC layer 206 supports additional RACH partitioning for Release 17 features. This allows RAN node 2 to identify early on Release 17 features or feature combinations selected, desired, or intended by UE1. For example, RACH resource partitions are set up for each of all or a subset of Release 17 features, and further RACH resource partitions are set up for each of the possible feature combinations or combinations of features. Each Release 17 feature is, for example, Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CE or CovEnh), or Slicing. A feature combination includes, for example, at least two of RedCap, SDT, CovEnh, and Slicing. The term “feature” as used herein hereafter means any of these Release 17 features unless otherwise specified. Similarly, the term “feature combination” means a combination consisting of at least two of these Release 17 features, unless otherwise specified. A “feature combination” may also be called a “feature set” or “set of features.”

[0045] RedCap indication in RACH is used to show 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 provided by the current NR standard. 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 compared to 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 capabilities for complexity or cost reduction compared to the baseline Release 15 NR device. According to the 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 the Release 15 NR device.

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

[0047] The CovEnh indicator in RACH is used to indicate the need for coverage enhancement, for example, for a request for repetition of the third RACH message (MSG3 in 4-step RA). The CovEnh indicator may also be binary information indicating whether Msg3 PUSCH repetition is required. Alternatively, the CovEnh indicator may indicate one of several coverage enhancement (CE) levels. The CovEnh indicator may indicate one of two or more CE level groups (or CE modes). A single CE level group or CE mode contains one or more CE levels. For example, CE as defined 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 at CE level 0 enjoys relatively low path loss and high downlink received power, while a UE at CE level 3 enjoys relatively high path loss and low downlink received power.

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

[0049] Network slicing uses Network Function Virtualization (NFV) and software-defined networking (SDN) technologies to enable the creation of multiple virtualized logical networks on top of a physical network. Each virtualized logical network is called a network slice or network slice instance and contains logical nodes and functions used for specific traffic and signaling. A network slice may also be a network slice provided by the core network (e.g., 5GC). Multiple network slices are distinguished, for example, by the services or use cases provided to UE1 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)). RAN node 2 may assign to UE1 the RAN slices and radio slices associated with the network slices of the core network selected for UE1, in order to provide end-to-end network slicing to UE1. Therefore, the Slicing display in RACH may be information about the network slices of the core network, information about RAN or radio slices, or information about end-to-end network slices.

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

[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 an S-NSSAI(s) included in a Configured NSSAI or an S-NSSAI(s) included in an Allowed NSSAI. Note that S-NSSAIs in a Requested NSSAI included in a NAS registration request message must be part of a Configured NSSAI and / or an Allowed NSSAI. Therefore, the intended network slice may be an S-NSSAI(s) included in a Requested NSSAI.

[0052] A Configured NSSAI includes one or more S-NSSAIs, each applicable to one or more Public Land Mobile Networks (PLMNs). A Configured NSSAI is, for example, set by a Serving PLMN and applied to that Serving PLMN. An Allowed NSSAI is provided to UE1 by a Serving PLMN and indicates one or more S-NSSAIs that UE1 can use in the Serving PLMN's current Registration Area. A Configured NSSAI may also be a Default Configured NSSAI. A Default Configured NSSAI is set by a Home PLMN (HPLMN) and applies to any PLMNs for which no specific Configured NSSAI is provided. UE1 may be pre-configured with a Default Configured NSSAI. UE1 may be provisioned or updated with a Default Configured NSSAI determined by the HPLMN's Unified Data Management (UDM). The Allowed NSSAI is determined by the Serving PLMN's AMF, for example, during the registration procedure. The Allowed NSSAI is signaled to UE1 by the network (i.e., AMF) and stored in the (non-volatile) memory of both AMF and UE1.

[0053] The above describes the operation of AS layer 208 based on NAS-initiated access attempts, with reference to Figure 2. Of course, the operations performed by AS layer 208 are not limited to these. For example, RRC layer 203 performs cell selection and reselection. Specifically, when the RRC state of UE1 is RRC_IDLE or RRC_INACTIVE, RRC layer 203 searches for a suitable cell for camping on according to cell selection criteria or cell reselection criteria. Once a suitable cell for camping on is found, RRC layer 203 camps on to that cell. Camping on to 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 in a cell and is ready to initiate a potential dedicated service in that cell. In particular, when UE1 is RRC_IDLE or RRC_INACTIVE, the serving cell of UE1 can be said to be the cell to which UE1 is camped. A serving cell is sometimes called a camped cell.

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

[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 (e.g., the RRC layer 203).

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

[0057] Figure 3 shows an example of UE1's behavior regarding NAS-initiated access attempts. In step 301, the NAS layer 202 passes information about the first feature to the AS layer 208, specifically to the RRC layer 203. For example, the NAS layer 202 may send this information to the RRC layer 203 along with a request to send a NAS message. The NAS layer 202 may also send this information to the RRC layer 203 along with a request for a transition from RRC_IDLE or RRC_INACTIVE to RRC_CONNETED.

[0058] The first feature may relate to information, state, or function managed by NAS layer 202. The first feature may relate to information, state, or function configured on UE1 via NAS signaling by the core network. The first feature may also be a Release 17 feature, specifically a “Slicing”. In this case, the information regarding the first feature may indicate one or more network slices intended by NAS layer 202. As described above, each of the one or more intended network slices may be identified by an identifier known as S-NSSAI. The intended network slice may be an S-NSSAI(s) included in a Configured NSSAI, or an S-NSSAI(s) included in an Allowed NSSAI. The intended network slice may be an S-NSSAI(s) included in a Requested NSSAI.

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

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

[0061] In step 302, the AS layer 208 determines a feature combination that includes a first feature derived from the information received from the NAS layer 202 and one or more other features. The first feature and one or more other features may be Release 17 features. Specifically, the first feature may be Slicing, and 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 show the determined feature combination to the MAC layer 206 of UE1. Alternatively, the RRC layer 203 of UE1 may determine one or more features that should be included in the feature combination and show the determined one or more features to the MAC layer 206 of UE1. The MAC layer 206 may determine any further necessary features and determine the feature combination.

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

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

[0064] In step 301, the NAS layer 202 may also send information about a second feature (e.g., Mobile Terminated (MT) SDT-related information) to the AS layer 208 in addition to information about a first feature (e.g., slice-related information). 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 as described with reference to Figure 3. In step 401, the AS layer 208 of UE1 is RRC_INACTIVE. Although not shown, if UE1 receives an RRC Release message containing suspendConfig from RAN node 2 while being 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 NAS layer 202 is 5GMM-CONNECTED with RRC inactive indication.

[0066] In step 402, the NAS layer 202 is triggered to attempt access based on uplink user data packets sent for a PDU session using suspended user plane resources. This attempt relates to a specific network slice (e.g., Slice-X). In step 403, in response to the triggered 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 send uplink user data packets (i.e., MO data). This request indicates a specific network slice (e.g., Slice-X) to the RRC layer 203. 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 Figure 3.

[0067] Step 404 corresponds to step 302 in Figure 3. In step 404, the AS layer 208 performs 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 it is a prioritized network slice for RACH preamble transmission based on the network slice (or slice group, or priority level) indicated by the NAS layer 202. In addition, the RRC layer 203 determines whether to perform SDT. In other words, the RRC layer 203 decides whether to perform SDT or the normal RRC restart 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, MAC layer 206 determines the RACH resource for sending the RACH preamble from the set (or partition) of RACH resources associated with the feature combination indicated by RRC layer 203.

[0068] According to the operation of UE1 as described with reference to Figure 3 or Figure 4 or both, the AS layer 208 can determine feature combinations that include features related to information (or states or functions) managed by the NAS layer 202. This thus provides an interaction between the NAS layer 202 and the AS layer 208 of UE1 for the determination of feature combinations.

[0069] In step 303 of Figure 3 or step 405 of Figure 4, if the set of random access resources associated with the feature combination is not configured (or unavailable) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may not send a random access preamble and instead notify the NAS layer 202 of a failure. The failure cause that the AS layer 208 sends to the NAS layer 202 may be "other" or a newly defined value. Alternatively, the AS layer 208 may perform one of the fallback actions described in detail in the third or fourth embodiment below.

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

[0071] Figure 5 shows a different solution from that in Figure 3. In step 501, the NAS layer 202 passes information indicating the feature combination to the AS layer 208, specifically to the RRC layer 203. For example, the NAS layer 202 may send this information to the RRC layer 203 along with a request to send a NAS message. The NAS layer 202 may also send this information to the RRC layer 203 along with a request for a 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 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 a Configured NSSAI or S-NSSAI(s) included in an Allowed NSSAI. Alternatively, the information indicating the feature combination may indicate one or more network slice groups intended by NAS layer 202. Each of the one or more intended network slice groups may be identified by a slice group ID. The mapping of each network slice group to one or more network slices may be provided to UE1 (NAS layer 202) via NAS signaling by the core network (e.g., AMF). Alternatively, the information regarding the first feature may indicate one or more network slice priority levels. The mapping between each slice priority level and one or more network slices may be provided to UE1 (NAS layer 202) via NAS signaling by the core network (e.g., AMF).

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

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

[0075] Figure 6 shows a specific example of the operation of UE1 as described with reference to Figure 5. In step 601, the AS layer 208 of UE1 is RRC_INACTIVE. Although not shown, if UE1 receives an RRC Release message containing suspendConfig from RAN node 2 while being 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 NAS layer 202 is 5GMM-CONNECTED with RRC inactive indication.

[0076] In step 602, AS layer 208 sends an MT-SDT indication to NAS layer 202. For example, AS layer 208 may send an MT-SDT indication to NAS layer 202 in response to receiving paging indicating or relating to MT-SDT from the core network (e.g., AMF) via RAN node 2. Alternatively, AS layer 208 may send an MT-SDT indication to NAS layer 202 in response to receiving paging indicating or relating to MT-SDT (i.e., RAN paging) from RAN node 2. Such RAN paging may be generated by RAN node 2 and sent to UE1 in response to RAN node 2 receiving data for a suspended DRB (or the corresponding QoS flow) from the core network (e.g., UPF). Such paging and RAN paging may include a flag indicating MT-SDT. Furthermore, or alternatively, such paging and RAN paging may include information about at least one of the DRB(s), PDU session(s), QoS flow(s), or one or more network slices (e.g., S-NSSAI(s)) subject to MT-SDT. Similar information may be included in the MT-SDT display from AS layer 208 to NAS layer 202. Alternatively, the MT-SDT display may be implicitly indicated by a display requesting the resume of a suspended DRB (or corresponding QoS flow).

[0077] In step 603, the NAS layer 202 is triggered by an MT-SDT display to attempt access 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 the RACH resources for sending the RACH preamble from the 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 the RACH resources for sending the RACH preamble from the 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 explicit information, for example, that MT-SDT should be performed on a suspended DRB (or QoS flow). Alternatively, the joint information may be implicit information, such as that the RRC connection should be resumed for data transmission on the DRB (or QoS flow).

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

[0079] In step 502 of Figure 5 or step 606 of Figure 6, if the set of random access resources associated with the feature combination is not configured (or unavailable) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may not send a random access preamble and instead notify the NAS layer 202 of a failure. The failure cause that the AS layer 208 sends to the NAS layer 202 may be "other" or a newly defined value. Alternatively, the AS layer 208 may perform one of the fallback actions described in detail in the third or fourth embodiment below.

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

[0081] Figure 7 shows an example of UE1's operation in a random access procedure. Steps 701-703 relate to random access resource selection. For example, UE1 may perform steps 701-703 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 combination of features selected, desired, or intended by UE1 is configured (or available). Note that RRC layer 203 can configure MAC layer 206 with multiple resource sets (or resource partitions) including the first set. RRC layer 203 receives the random access configuration via broadcast from RAN node 2 and configures MAC layer 206 with the multiple resource sets (or resource partitions) indicated in the random access configuration.

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

[0084] Furthermore, 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 can be configured as a complement to the NUL carrier. Generally, to complement the coverage of the NUL carrier, the SUL carrier uses a lower uplink frequency than the NUL carrier. UE1 (MAC layer 206) may select one of the uplink carriers, the NUL carrier or the SUL carrier, based on downlink measurement results. For example, UE1 may operate similarly to the selection between NUL and SUL carriers in 3GPP Release 15 and / or Release 16. If the RSRP of the downlink pathloss reference 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] A network (e.g., RAN node 2) does not necessarily have to support the same features or combinations of features on both the NUL and SUL carriers. Therefore, in step 701, UE1 (MAC layer 206) may determine whether a first set of random access resources associated with the feature combination selected, desired, or intended by UE1 is available on the selected uplink carrier. If the answer in step 701 is YES, this means that the feature combination selected, desired, or intended by UE1 is supported (or available) on the selected uplink carrier. If the answer in step 701 is NO, this 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 in step 701 is YES, then UE1 (MAC layer 206) selects a random access resource from the first set (step 702).

[0087] If the answer in step 701 is NO, UE1 (MAC layer 206) selects a random access resource from a second set of random access resources associated with feature subsets included in the selected feature combination (step 703). A feature subset may also be called a feature subset, feature subcombination, or feature subcombination. A feature subset contains 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 also contain one or more features supported (or executable) in cell 21. UE1 may select a feature subset that should be preferred, or a feature subset that is more necessary (or important). For example, when the feature combination includes RedCap and one or more other features, UE1 may always include RedCap in the feature subset.

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

[0089] If the fallback operations in steps 703 and 704 are performed, the AS layer 208 of UE1 may notify the NAS layer 202 of a random access failure or a fallback to a feature subset corresponding to the originally intended feature combination. Furthermore, or alternatively, if a feature subset is also unavailable 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 feature that should (be highest) priority among the feature combinations. Alternatively, the AS layer 208 may notify the NAS layer 202 of a failure relating to a feature for which the AS layer 208 (e.g., MAC layer 206) is not permitted to determine whether the execution of that feature (or its function) is necessary or possible.

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

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

[0092] Figure 8 shows an example of UE1's operation in a random access procedure. Steps 801-803 relate to random access resource selection. For example, UE1 may perform steps 801-803 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 combination of features selected, desired, or intended by UE1 is configured (or available). Note that RRC layer 203 can configure MAC layer 206 with multiple resource sets (or resource partitions) including the first set. RRC layer 203 receives the random access configuration via broadcast from RAN node 2 and configures MAC layer 206 with the multiple resource sets (or resource partitions) indicated in the random access configuration.

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

[0095] Furthermore, UE1 (MAC layer 206) may make a selection between NUL carriers and SUL carriers prior to random access resource selection. SUL carriers can be configured to complement NUL carriers. Generally, SUL carriers use lower uplink frequencies than NUL carriers to complement the coverage of NUL carriers. UE1 (MAC layer 206) may select one of the uplink carriers, NUL carrier or SUL carrier, based on downlink measurement results. For example, UE1 may operate similarly to the selection between NUL and SUL carriers in 3GPP Release 15 and / or Release 16. If the downlink path loss-based 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.

[0096] A network (e.g., RAN node 2) does not necessarily have to support the same features or combinations of features on both the NUL and SUL carriers. Therefore, in step 801, UE1 (MAC layer 206) may determine whether a first set of random access resources associated with the feature combination selected, desired, or intended by UE1 is available on the selected uplink carrier. If the answer in step 801 is YES, this means that the feature combination selected, desired, or intended by UE1 is supported (or available) on the selected uplink carrier. If the answer in step 801 is NO, this 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 in step 801 is YES, then UE1 (MAC layer 206) selects a random access resource from the first set (step 1102).

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

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

[0100] If the fallback actions in steps 803 and 804 are performed, 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 random access that does not consider the feature combination.

[0101] According to the operation of UE1 as described with reference to Figure 8, if cell 21 does not provide a set of RACH resources associated with a feature combination selected, desired, or intended by UE1, UE1 selects a RACH resource for random access to cell 21 from an alternative set of RACH resources not associated with that feature combination. This operation of UE1 allows cell 21 or RAN node 2 to provide only a portion of the RACH resource sets for some of all possible features and feature combinations. Therefore, cell 21 does not necessarily have to provide all RACH resource sets for all possible features and feature combinations. This can contribute to reducing fragmentation of random access resources.

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

[0103] This embodiment relates to the 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, MAC layer 206 of UE1 determines whether the feature needs to be executed (or whether it is possible to execute the feature) based on information or conditions that it has predetermined. Alternatively, MAC layer 206 may make the above determination based on information received or specified from a higher layer of UE1 (e.g., RRC layer 203). In this type, if MAC layer 206 of UE1 determines that at least one feature of a selected, desired, or intended feature combination does not need to be executed (or cannot be executed), MAC layer 206 may modify the contents of the feature combination (i.e., the included features) to select RACH resources for the remaining features or feature combinations excluding that feature. In other words, MAC layer 206 may select a feature subset that excludes the features that do not need to be executed (or cannot be executed). In this case, MAC layer 206 may notify RRC layer 203 of the determination result (for example, information on the feature combination to be executed, information on the excluded features).

[0104] The second type is one in which the MAC layer 206 of UE1 does not, or should not, determine whether the execution of the feature is necessary (or whether the execution of the feature is possible). In this type, the RRC layer 203 of UE1 determines whether the execution of the feature is necessary (or whether the execution of the feature is possible) and notifies the MAC layer 206 of the necessary information. The determination by the RRC layer 203 may be based on either or both of the capabilities of UE1 and predetermined information held by the RRC layer 203. Furthermore, or alternatively, the RRC layer 203 may determine the above 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 combination of features containing the feature. If the MAC layer 206 determines that there is no RACH resource corresponding to the feature, it may report a failure indication to the RRC layer 203. On the other hand, if MAC layer 206 determines that there is no RACH resource corresponding to the feature combination containing the feature in question, MAC layer 206 may exclude one or more features belonging to the first type from the feature combination and select a RACH resource corresponding to a feature subset that includes the features of the second type and the remaining one or more features belonging to the first type. Alternatively, MAC layer 206 may select a RACH resource that corresponds only to the features of the second type. In other words, if it is necessary to select a feature subset from a feature combination, MAC layer 206 may ensure that one or more features of the second type (e.g., RedCap) that were included in the feature combination are included in the feature subset. MAC layer 206 may then adjust the number of features in the feature subset depending on whether or not the features of the first type that were included in the feature combination are included in the feature subset.

[0105] The feature combination selected, desired, or intended by UE1 may include only one of the two types described above, or it may include both types. If the feature combination includes both types, MAC layer 206 may prioritize the features of the second type. For example, MAC layer 206 may prioritize executing features of the second type. MAC layer 206 may also prioritize selecting RACH resources corresponding to features of the second type.

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

[0107] In this embodiment, UE1 considers, in cell selection, re-selection, or both, whether candidate cells provide a separate set of random access resources for a feature or feature combination selected, desired, or intended by UE1. A feature may be any of the Release 17 features. A feature combination may be a combination of Release 17 features. A feature may be RedCap, SDT, CovEnh, or Slicing. A 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 representation of the Release 17 feature or feature combination via random access resources used for preamble transmission.

[0108] UE1 (RRC layer 203) may consider cells or frequency bands that provide a separate set of preamble resources for a feature or feature combination to have higher priority for selecting cells to camp on than cells or frequency bands that do not provide such separate set of preamble resources. This behavior allows UE1 to preferentially select cells that provide a separate set of random access resources for a selected, desired, or intended feature or feature combination as a cell to camp on.

[0109] Specifically, in intra-frequency, or intra-frequency-band, cell (re)selection, UE1 may operate as follows: UE1 (RRC layer 203) selects the second highest-ranked cell as the camp-on cell if the highest-ranked cell in the first frequency band does not provide the set, but the second highest-ranked cell in the first frequency band does.

[0110] Furthermore, or alternatively, in inter-frequency, i.e., inter-frequency-band cell (re)selection, UE1 may operate as follows: UE1 (RRC layer 203) may select the highest-ranked cell in the second frequency band as the camp-on cell if the highest-ranked cell in the first frequency band does not provide the individual set, but the highest-ranked cell in the second frequency band does. Alternatively, UE1 (RRC layer 203) may select a cell in the second frequency band as the camp-on cell if the first frequency band does not support providing the individual set, but the second frequency band does. The first and second frequency bands may have equal priority. Alternatively, the first frequency band may have higher priority than the second frequency band.

[0111] Figure 9 shows an example of UE1's operation during cell selection, re-selection, or both. In step 901, UE1 (RRC layer 203) initiates either a cell selection process or a cell re-selection 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 re-selection evaluation process allows UE1, which is RRC_IDLE or RRC_INACTIVE, to select a more suitable cell. When UE1 is in the Camped Normal state, UE1 attempts to detect, synchronize, and monitor intra-frequency, inter-frequency, and inter-RAT cells as indicated by the serving cell (e.g., cell 21).

[0112] In step 902, UE1 (RRC layer 203) selects or re-selects a cell to camp on from one or more candidate cells, taking into consideration whether the candidate cell provides a separate set of random access resources for a feature or feature combination. As described above, UE1 (RRC layer 203) may consider cells or frequency bands that provide a separate set of preamble resources for a feature or feature combination to have a higher priority for selecting a cell to camp on than cells or frequency bands that do not provide such a separate set of preamble resources. In step 903, UE1 camps on to the selected or re-selected cell. UE1 may also receive system information (e.g., SIB1) broadcast by the candidate cell for cell (re)selection and determine, based on the received system information, whether the candidate cell provides a separate set of random access resources for a feature or feature combination. Alternatively, the system information (e.g., SIB1) broadcast by the current cell (serving cell) may indicate whether they are provided by adjacent cells, and UE1 may make a determination based on this.

[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 considered (or prioritized) for cell selection or reselection. Therefore, UE1 can preferentially select cells that support random access based on Release 17 features or feature combinations during 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 two types described above, or it may include both types. If the feature combination includes both types, UE1 (RRC layer 203) may give preference to the second type of feature in cell selection or re-selection. For example, RRC layer 203 may consider cells or frequency bands in which the second type of feature (or feature subset) is available to have higher priority for selecting cells to camp on than cells or frequency bands in which it is not available. This behavior allows UE1 to preferentially select cells in which the second type of feature (or feature subset) is available as a cell to camp on. Alternatively, RRC layer 203 may consider cells or frequency bands that provide a separate preamble resource set for the second type of feature (or feature subset) to have higher priority for selecting cells to camp on than cells or frequency bands that do not provide it. This behavior allows UE1 to preferentially select a cell that provides a separate preamble resource set for a second type of feature (or feature subset) as a cell to camp on.

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

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

[0117] In this embodiment, UE1 (RRC layer 203) considers cells that support the intended network slice and provide a separate set of random access resources for Release 17 features or feature combinations to have higher priority for selecting cells to camp on than cells that do not support the network slice or do 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 a Configured NSSAI or an S-NSSAI included in an Allowed NSSAI. NAS layer 202 may indicate an intended network slice group to RRC layer 203. The intended network slice group may be identified by a slice group ID. The mapping of a network slice group to one or more network slices may be provided to UE1 (NAS layer 202) via NAS signaling by the core network (e.g., AMF). 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 the UE1 (NAS layer 202) via NAS signaling by the core network (e.g., AMF).

[0118] In one implementation, AS layer 208 may select the most appropriate cell by a slice-based (or slice-group-based) cell (re)selection process, and then perform a cell (re)selection process to prioritize the availability of random access based on Release 17 features or feature combinations. This may be done, for example, as shown in Figure 10.

[0119] In step 1001, AS layer 208 performs a slice-based (or slice-group-based) cell (re)selection process. Specifically, RRC layer 203 selects a first candidate cell based on the network slice or network slice group intended by 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 AS layer 208 may be performed, for example, as follows: • Step 1: Sort the slices in order of priority, starting with the highest priority slice. Step 2: Select slices in order of priority from the sorted slice list. • Step 3: Assign priority to frequencies or frequency bands for the selected slice. The priority of frequencies or frequency bands is set by the network (e.g., RAN node 2, or AMF). Step 4: Perform downlink measurements starting from the highest priority frequency (band), similar to those for Release 15 and Release 16. Step 5: If the highest-ranking cell is suitable in terms of wireless quality and supports the slice selected in Step 2, select that cell as the first cell and exit the sequence. Step 6: If there are remaining frequencies, return to Step 4. Step 7: If you haven't reached the end of the slice list, go back to Step 2. Step 8: Legacy cell reselection, i.e., cell reselection similar to that in Release 15 and Release 16.

[0121] Next, in step 1002, the RRC layer 203 performs a cell (re)selection process to prioritize the availability of random access based on Release 17 features or combinations of features. If the first cell has been selected according to the sequence described in the previous paragraph, the RRC layer 203 may perform step 1002 after terminating that sequence in step 5.

[0122] Specifically, RRC layer 203 may (re)select as a camp-on cell 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 separate set of random access resources for features or feature combinations. In one example, the predetermined radio quality criterion is that the value obtained by subtracting the downlink quality metric of the second candidate cell from the downlink quality metric of the first candidate cell (e.g., RSRP, RSRQ, Srxlev, Squal) 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 value obtained by subtracting a threshold from the downlink quality metric of the first candidate cell. The threshold may be predetermined or set by the network (e.g., RAN node 2).

[0123] In other implementations, AS layer 208 may perform a cell (re)selection process to prioritize the availability of random access based on Release 17 features or feature combinations, concurrently with (or in parallel with) the slice-based (or slice-group-based) cell (re)selection process. This may, for example, occur midway through 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, AS layer 208 (RRC layer 203) may prioritize candidate cells that provide a separate set of random access resources for features or feature combinations.

[0124] In other implementations, AS layer 208 may select appropriate cells by a cell (re)selection process that prioritizes the availability of random access based on Release 17 features or feature combinations, followed by slice-based (or slice-group-based) cell (re)selection. For example, AS layer 208 may preferentially select cells for which random access based on Release 17 features or feature combinations is available as candidate cells, 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 two types described above, or it may include both types. If the feature combination includes both types, UE1 (RRC layer 203) may give preference to the second type of feature in cell selection or re-selection. For example, RRC layer 203 may consider cells or frequency bands in which the second type of feature (or feature subset) is available to have higher priority for selecting cells to camp on than cells or frequency bands in which it is not available. This behavior allows UE1 to preferentially select cells in which the second type of feature (or feature subset) is available as a cell to camp on. Alternatively, RRC layer 203 may consider cells or frequency bands that provide a separate preamble resource set for the second type of feature (or feature subset) to have higher priority for selecting cells to camp on than cells or frequency bands that do not provide it. This behavior allows UE1 to preferentially select a cell that provides a separate preamble resource set for a second type of feature (or feature subset) as a cell to camp on.

[0126] Next, the following describes configuration examples of UE1 and RAN node 2 according to the above-described multiple embodiments. Figure 11 is a block diagram showing a configuration example of UE1. The Radio Frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with the 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 with the antenna array 1102 and the 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 supplies the transmit RF signal to the antenna array 1102. The RF transceiver 1101 also generates a baseband receive signal based on the received RF signal received by the antenna array 1102 and supplies it to the baseband processor 1103. The RF transceiver 1101 may include an analog beamformer circuit for beamforming. The analog beamformer circuit 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) generation / decomposition of transmission format (transmission frame), (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). Control plane processing, on the other hand, includes communication management at 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 attach, mobility, and call management).

[0128] For example, the digital baseband signal processing by the baseband processor 1103 may include signal processing for the Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and Physical (PHY) layer. Furthermore, the control plane processing by the baseband processor 1103 may include processing for the Non-Access Stratum (NAS) protocol, 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., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or 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 described later.

[0131] The application processor 1104 is also called a CPU, MPU, microprocessor, or processor core. The application processor 1104 may include multiple processors (multiple processor cores). The application processor 1104 implements various functions of the UE1 by executing system software programs (Operating System (OS)) and various application programs (e.g., calling applications, web browsers, mail clients, camera operation applications, music playback applications) read from memory 1106 or memory not shown.

[0132] In some implementations, the baseband processor 1103 and the application processor 1104 may be integrated on a single chip, as shown 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 chipset.

[0133] Memory 1106 is volatile memory, non-volatile memory, or a combination thereof. Memory 1106 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 1106 may include an external memory device accessible from the baseband processor 1103, the application processor 1104, and the SoC 1105. Memory 1106 may also include an internal memory device integrated within the baseband processor 1103, the application processor 1104, or the SoC 1105. Furthermore, 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 containing instruction sets and data for performing the processing by the UE1 as described in the above embodiments. In some implementations, the baseband processor 1103 or application processor 1104 may be configured to read and execute the software modules 1107 from the memory 1106 to perform the processing of the UE1 as described in the above embodiments with reference to the drawings.

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

[0136] Figure 12 is a block diagram showing an example configuration of RAN node 2 according to the embodiment described above. Referring to Figure 12, 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 to communicate with UEs, including UE1. The RF transceiver 1201 may include multiple transceivers. The RF transceiver 1201 is coupled with an antenna array 1202 and a processor 1204. The RF transceiver 1201 receives modulation symbol data from the processor 1204, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1202. The RF transceiver 1201 also generates a baseband receive signal based on the received RF signal received by the antenna array 1202 and supplies it to the processor 1204. The RF transceiver 1201 may include an analog beamformer circuit for beamforming. The analog beamformer circuit 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, as well as control and forwarding nodes of the core network). The network interface 1203 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0138] Processor 1204 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Processor 1204 may include multiple processors. For example, processor 1204 may include a modem processor (e.g., Digital Signal Processor (DSP)) for digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) for control plane processing. 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] Memory 1205 is comprised of a combination of volatile and non-volatile memory. Volatile memory may be, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory may be Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. Memory 1205 may also include storage located away from the processor 1204. In this case, the processor 1204 may access 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 containing instruction sets and data for processing by the RAN node 2 as described in the above embodiments. In some implementations, the processor 1204 may be configured to read the software modules 1206 from the memory 1205 and execute them to perform the processing of the RAN node 2 as described in the above embodiments.

[0141] Furthermore, if RAN node 2 is a CU (e.g., gNB-CU) or CU-CP (e.g., gNB-CU-CP), RAN node 2 does not need to include RF transceiver 1201 (and antenna array 1202).

[0142] As illustrated with reference to Figures 11 and 12, each of the processors in the UE1 and RAN node 2 according to the above embodiment can execute one or more programs, each containing a set of instructions for causing a computer to perform the algorithms described with reference to the drawings. The program, when loaded into a computer, contains a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiment. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited, of the computer-readable medium or physical storage medium include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited, of the temporary computer-readable medium or communication medium include electrical, optical, acoustic or other forms of propagating signals.

[0143] <Other Embodiments> In the embodiments described above, “features” may be features newly introduced in future 3GPP Release 18 or later. Similarly, in the embodiments described above, “feature combinations” may include features newly introduced in future 3GPP Release 18 or later. For example, in addition to Mobile Originated (MO) SDT introduced in Release 17, Mobile Terminated (MT) SDT is planned to be added in 3GPP Release 18. In one implementation, feature MT-SDT may be distinguished from feature MO-SDT, and a separate RACH resource set (or partition, or pool) may be configured for feature MT-SDT. In this case, feature combinations may include MT-SDT. RAN node 2 may inform UE1 whether MO-SDT and MT-SDT are distinguished in the RACH resource partition via broadcast (e.g., SIB) or individual RRC signaling. Specifically, the random access configuration (e.g., RACH-Config) sent from RAN node 2 to UE1 may include a 1-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 feature (MO-)SDT for MT-SDT. Conversely, 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 that separate RACH resource set for MT-SDT. If the random access configuration does not include this flag and no separate RACH resource set is configured for MT-SDT, 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 feature (MO-)SDT for MT-SDT, or it may use the same RACH resource set for MT-SDT as in Release 15 and / or Release 16.

[0144] In the embodiments described above, if a setting (e.g., random access setting) received via RRC signaling (e.g., SIB) includes a setting, information, or field relating to a feature not supported by UE1 (e.g., Release 17 feature), UE1 may operate in a manner that does not ignore the value (or code point) of such setting, 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 the desired feature or feature combination and the value of the second ra-PreambleStartIndex field for the next feature or feature combination. In this case, UE1 must not ignore the value of the second ra-PreambleStartIndex field, regardless of whether it supports the feature or feature combination associated with the second ra-PreambleStartIndex field.

[0146] In some of the embodiments described above, UE1 may perform different actions (or processes) for a particular feature or a combination of features containing it compared to the embodiments described above. For example, with respect to uplink carrier selection, the uplink carrier to be selected (e.g., NUL carrier) may be predetermined (or specified in the specification) for a particular feature (e.g., RedCap) or a combination of features containing it. This is useful for fully utilizing the functionality of the feature or for considering limitations in the functionality of the feature.

[0147] In some of the embodiments described above, UE1 may perform different actions (or processes) for certain features or combinations of features containing such features compared to the embodiments described above. For example, for a particular feature (e.g., Coverage enhancement), after uplink carrier selection, UE1 may decide whether or not the feature is necessary (or whether or not to perform the feature). This is useful when the functionality of the feature depends on the result of uplink carrier selection.

[0148] Furthermore, the embodiments described above are merely examples of how the technical concept obtained by the present inventor can be applied. In other words, the technical concept is not limited to the embodiments described above, and various modifications are certainly possible.

[0149] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0150] (Note 1) At least one memory, The system comprises 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 regarding the first feature to the AS layer function. The aforementioned AS layer function is Determine a feature combination that includes the first feature derived from the aforementioned information and one or more other features. A random access resource is selected from a first set of random access resources associated with the feature combination determined by the AS layer function. The random access preamble is sent using the selected random access resource. Structured in such a way Wireless terminal. (Note 2) The first characteristic mentioned above is slicing, The aforementioned one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh). The wireless terminal described in Appendix 1. (Note 3) The information relating to the first feature above 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. Wireless terminal as described in Appendix 1 or 2. (Note 4) The information relating to the first feature indicates one or more Single Network Slice Selection Assistance Information (S-NSSAI) to indicate the intended one or more network slices. The wireless terminal described in Appendix 3. (Note 5) The AS layer function is configured to notify the NAS layer of the failure without sending a random access preamble if the first set is not available in the serving cell. A wireless terminal as described in any one of the items 1 to 4 in the appendix. (Note 6) The aforementioned AS layer function is If the first set is not available in the serving cell, select a random access resource from a second set of random access resources associated with the feature subset included in the feature combination. Send a random access preamble using a random access resource selected from the second set mentioned above. Structured in such a way A wireless terminal as described in any one of the items 1 to 4 in the appendix. (Note 7) The aforementioned AS layer function is If the first set is not available in the serving cell, select a random access resource from a third set of random access resources not associated with the feature combination. Send a random access preamble using a random access resource selected from the third set. Structured in such a way A wireless terminal as described in any one of the items 1 to 4 in the appendix. (Note 8) To provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality. The NAS layer function passes information regarding the first feature to the AS layer function. The AS layer function determines a feature combination that includes the first feature derived from the information and one or more other features. The AS layer function selects 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 performs random access preamble transmission on the selected random access resource. Equipped with, A method performed using wireless terminals. (Note 9) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, To provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality. The NAS layer function passes information regarding the first feature to the AS layer function. The AS layer function determines a feature combination that includes the first feature derived from the information and one or more other features. The AS layer function selects 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 performs random access preamble transmission on the selected random access resource. Equipped with, program. (Note 10) At least one memory, The system comprises 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 feature combinations to the AS layer function. The aforementioned AS layer function is A random access resource is selected from a first set of random access resources associated with the feature combination indicated by the NAS layer function. The random access preamble is sent using the selected random access resource. Structured in such a way Wireless terminal. (Note 11) The aforementioned feature combination includes Slicing and one or more other features. The wireless terminal described in Appendix 10. (Note 12) The aforementioned one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh). The wireless terminal described in Appendix 11. (Note 13) The aforementioned one or more other features include at least Small Data Transmission (SDT). Wireless terminal as described in Appendix 11 or 12. (Note 14) The information representing the aforementioned feature combination indicates one or more network slices intended by the NAS layer function. A wireless terminal as described in any one of the items 10 to 13 of the appendix. (Note 15) The information representing the aforementioned feature combination includes one or more Single Network Slice Selection Assistance Information (S-NSSAI) to indicate the intended one or more network slices. The wireless terminal described in Appendix 14. (Note 16) The AS layer function is configured to notify the NAS layer of the failure without sending a random access preamble if the first set is not available in the serving cell. A wireless terminal as described in any one of the items 10 to 15 of the appendix. (Note 17) The aforementioned AS layer function is If the first set is not available in the serving cell, select a random access resource from a second set of random access resources associated with the feature subset included in the feature combination. Send a random access preamble using a random access resource selected from the second set mentioned above. Structured in such a way A wireless terminal as described in any one of the items 10 to 15 of the appendix. (Note 18) The aforementioned AS layer function is If the first set is not available in the serving cell, select a random access resource from a third set of random access resources not associated with the feature combination. Send a random access preamble using a random access resource selected from the third set. Structured in such a way A wireless terminal as described in any one of the items 10 to 15 of the appendix. (Note 19) To provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality. The NAS layer function passes information indicating feature combinations to the AS layer function. The AS layer function selects 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 performs random access preamble transmission on the selected random access resource. Equipped with, A method performed using wireless terminals. (Note 20) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, To provide Non-Access Stratum (NAS) layer functionality and Access Stratum (AS) layer functionality. The NAS layer function passes information indicating feature combinations to the AS layer function. The AS layer function selects 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 performs random access preamble transmission on the selected random access resource. Equipped with, program. (Note 21) At least one memory, The system comprises at least one processor coupled to the at least one memory, The at least one processor is configured to consider, when selecting or re-selecting a cell to camp on from one or more candidate cells, whether the candidate cell provides a separate set of random-access resources for selected, desired, or intended features or feature combinations. Wireless terminal. (Note 22) The at least one processor is configured to consider a cell or frequency band that provides the individual set as having a higher priority for selecting the cells to camp on than a cell or frequency band that does not provide the individual set. The wireless terminal described in Appendix 21. (Note 23) The at least one processor is configured to select the second-highest ranked cell as the camp-on cell if the highest-ranked cell in the first frequency band does not provide the individual set, but the second-highest ranked cell in the first frequency band does provide the individual set. The wireless terminal described in Appendix 21 or 22. (Note 24) The at least one processor is configured to select the highest-ranking cell in the second frequency band as the camp-on cell if the highest-ranking cell in the first frequency band does not provide the individual set, and the highest-ranking cell in the second frequency band does provide the individual set. The wireless terminal described in Appendix 21 or 22. (Note 25) The at least one processor is configured to select a cell in the second frequency band as the camp-on cell if the first frequency band does not support providing the individual sets and the second frequency band supports providing the individual sets. The wireless terminal described in Appendix 21 or 22. (Note 26) The at least one processor is configured to consider a cell that supports and provides an intended network slice, network slice group, or network slice priority level as having a higher priority for selecting the camp-on cell 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 as described in any one of the items 21 to 25 of the appendix. (Note 27) The aforementioned at least one processor is Based on the intended network slice or network slice group, select the first candidate cell. A second candidate cell is selected as the camp-on cell, which is in the same frequency band as the first candidate cell, meets predetermined radio quality standards, and provides the individual set. Structured in such a way A wireless terminal as described in any one of the items 21 to 26 of the appendix. (Note 28) The aforementioned features are Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing. The aforementioned feature combination includes at least two of RedCap, SDT, CovEnh, and Slicing. A wireless terminal as described in any one of the items 21 to 27 of the appendix. (Note 29) When selecting or re-selecting cells to camp on from one or more candidate cells, the system includes considering whether the candidate cells provide a separate set of random-access resources for selected, desired, or intended features or feature combinations. A method performed using wireless terminals. (Note 30) A program for causing a computer to perform a method for wireless terminals, The method comprises, when selecting or re-selecting a cell to camp on from one or more candidate cells, considering whether the candidate cell provides a separate set of random-access resources for selected, desired, or intended features or feature combinations. program.

[0151] This application claims priority based on Japanese Patent Application No. 2021-171921, filed on 20 October 2021, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0152] 1 UE 2, 3 RAN nodes Cells 21 and 31 1103 Baseband Processor 1104 Application Processor 1106 memory 1107 Modules 1204 Processor 1205 memory 1206 modules

Claims

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

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

3. The system further includes means for determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison of RSRP and rsrp-ThresholdSSB-SUL, before determining whether the first set is available. The wireless terminal according to claim 1.

4. Receiving information about slices from the core network, Receiving system information, including random access settings, from a wireless access network node. Determining whether a first set of random access resources associated with a feature or feature combination selected, desired, or intended by a wireless terminal is available, from among any one feature of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a combination of features including at least two of the above: RedCap, SDT, CovEnh, and Slicing. If the first set is available, select a first random access resource from the first set, and use the selected first random access resource to send a random access preamble, and If the first set is unavailable, select a second random access resource from a second set of random access resources not associated with the features or combination of features, and use the selected second random access resource to send a random access preamble. A method performed by a wireless terminal equipped with the above.

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

6. The system further comprises determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison of RSRP and rsrp-ThresholdSSB-SUL, before determining whether the first set is available. The method according to claim 4.

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