Wireless terminal, wireless access network node and methods thereof

Abstract

An NAS layer (202) of this radio terminal (1) sends information related to a first characteristic to an AS layer (208). The AS layer (208) determines a characteristic combination including a first characteristic and one or more other characteristics derived from the information. The AS layer (208) selects a random access resource from a first set of random access resources associated with the determined characteristic combination. The AS layer (208) uses the selected random access resource to transmit a random access preamble. This can contribute, for example, to provision of the interaction between the non-access stratum (NAS) layer and the access stratum (AS) layer of a radio terminal for determining a characteristic combination.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication network, and 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 support for additional random access resource partitioning. This feature 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 notify 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 refer to random access preambles, or combinations of random access opportunities and random access preambles. Random access resource partitioning is also referred to as Random Access Channel (RACH) resource partitioning or RACH partitioning. Random access opportunities are also called RACH occasions (ROs), and random access preambles are also called RACH preambles. One RACH occasion is the time and frequency resources for RACH preamble transmission. According to the current 3GPP Release 15 and Release 16 specifications, one RACH occasion has a maximum of 64 RACH preambles available for transmission.

[0004] In the RACH partitioning of 3GPP Release 16, the UE can inform the gNB of the following information depending on which RACH preamble is used. - The selected Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) (or the 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 earlier, further RACH partitioning is being 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 (or combinations of features) need to 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 be referred to as functional features.

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

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

[0008] The CovEnh indication in RACH is used to indicate the need for coverage enhancement and is used, for example, for the repetition request of the 3rd RACH message (MSG3 in 4-step RA). The CovEnh indication may be binary information indicating whether Msg3 PUSCH repetition is required.

[0009] The Slicing indication in RACH indicates a high-priority slice to the network and is used to achieve slice isolation for RACH. The Slicing indication may be binary information for distinguishing between prioritized and non-prioritized network slices. Alternatively, the Slicing indication may indicate multi-level slice priority, a selected or intended network slice, or a selected or intended network slice group, which will lead to a further increase in the number of partitions.

[0010] Furthermore, the 3GPP RAN Working Group is considering enhancements to cell selection and reselection for slicing. This function is also planned to be introduced in 3GPP Release 17 (see, for example, Non-Patent Documents 5-8). This function is also called slice-based (or slice-group-based) cell (re)selection. This enables the UE's Access Stratum (AS) layer to preferentially select or reselect cells that support the 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 Documents

[0011] [Non-Patent Document 1] ZTE Corporation, "RRC and MAC related aspects of common RACH configuration", R2-2107484, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-Patent Document 2] NEC, "General aspects of RACH indication and partitioning", R2-2108138, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-Patent Document 3] Ericsson, "RACH partitioning for Rel-17 features", R2-2108253, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-Patent Document 4] InterDigital, "Report for Rel-17 Small data and URLLC / IIoT", R2-2108834, 3GPP TSG-RAN WG2 #115-e Electronic meeting, August 16 - 27, 2021 [Non-Patent Document 5] 3GPP TR 38.832 V17.0.0 (2021-06) "3rd Generation Partnership Project; Technical Specification Group RAN; NR; Study on enhancement of Radio Access Network (RAN) slicing (Release 17)", June 2021 [Non-Patent Document 6] Intel Corporation, "Frequency prioritization for slice specific cell (re)selection", R2-2104873, 3GPP TSG RAN WG2 #114-e Electronic meeting, May 19 - 27, 2021 [Non-Patent Document 7] CMCC, "Discussion on slice based cell reselection", R2-2106224, 3GPP TSG RAN WG2 #114-e Electronic meeting, May 19 - 27, 2021 [Non-Patent Document 8] Nokia, "Report on LTE legacy, Mobility, DCCA, Multi-SIM and RAN slicing", R2-2106471, 3GPP TSG RAN WG2 #114-e Electronic meeting, May 19 - 27, 2021 [Summary of the Invention] [Problems to be Solved by the Invention]

[0012] The inventor of the present case examined random access resource partitioning for Release 17 features and feature combinations and found various problems.

[0013] One of these problems relates to the interaction between the UE's NAS layer and the UE's AS layer in the selection of feature combinations. For example, as described above, the new Release 17 features currently envisioned for additional RACH partitioning include "Slicing". Whether Slicing indication in RACH is required is considered 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 the feature combination is performed by the UE's AS layer. In such a case, it is not clear how the interaction between the UE's NAS layer and the UE's AS layer is performed for the determination of the feature combination or the random access resource selection corresponding to the feature combination.

[0014] Another one of these problems relates to cell selection or reselection or both. According to the inventors' consideration, in cell selection and cell reselection, it may be preferable for the UE to be able to preferentially select a cell that supports 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 indication of the Release 17 features or feature combinations via the random access resources used for preamble transmission. However, the availability of random access based on features or feature combinations being considered (or prioritized) for cell selection or reselection has not yet been discussed at present.

[0015] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to random access resource partitioning including the problems described above. It should be noted that this objective is only one of the multiple objectives to be achieved by the multiple embodiments disclosed in this specification. Other objectives or problems and novel features will be clarified from the description of this specification or the attached 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 a NAS layer function and an AS layer function. The NAS layer function is configured to pass information indicating a feature combination to the AS layer function. The AS layer function is configured to select a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function. The AS layer function is configured to perform a random access preamble transmission using the selected random access resource.

[0019] In a fourth 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 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 a sixth aspect, the method performed by a wireless terminal includes considering whether a candidate cell provides an individual set of random access resources for a selected, desired, or intended feature or combination of features when selecting or reselecting a cell to camp on from one or more candidate cells.

[0022] A 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 method according to the second, fourth, or sixth aspect described above.

Advantages of the Invention

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

Brief Description of the Drawings

[0024]

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Mode for Carrying Out the Invention

[0025] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted as necessary for clarity of explanation.

[0026] The plurality of embodiments described below can be implemented independently or can be implemented in appropriate combination. These plurality of embodiments have different novel features from each other. Therefore, these plurality of embodiments contribute to solving different objects or problems and contribute to achieving different effects.

[0027] The plurality of embodiments shown below are mainly described with respect to the 3GPP fifth-generation mobile communication system (5G system). However, these embodiments may be applied to other wireless communication systems.

[0028] As used herein, depending on the context, "(if)~then" may be construed to mean "when", "at or around the time", "after", "upon", "in response to determining", "in accordance with a determination", or "in response to detecting". These expressions may be construed to have the same meaning depending on the context.

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

[0030] UE1 has at least one wireless transceiver and is configured to perform cellular communication with RAN node 2 or 3 or both. RAN node 2 manages cell 21 and is configured to perform cellular communication with a plurality of UEs including UE1 using a cellular communication technology (e.g., NR Radio Access Technology (RAT)). RAN node 3 manages cell 31 and is configured to perform cellular communication with a plurality of UEs using a 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 it may be a combination of a CU and one or more Distributed Units (e.g., gNB-DUs). Similarly, RAN node 3 may be a CU, or it may include a CU and one or more DUs. C-RAN is also referred to as CU / DU split. Further, the CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Thus, each of RAN nodes 2 and 3 may be a CU-CP, or it may be a combination of a CU-CP and a CU-UP. The CU may be a logical node that hosts the Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB (or the RRC and PDCP protocols of the gNB). The DU may be a logical node that hosts the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of the gNB.

[0032] RAN node 2 transmits signals including System Information (SI) 101 and other signals within 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 includes the basic information necessary for initial access and the 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), and Other SI includes SIB types after SIB type 2 (SIB2). Each SIB included in Other SI is either always broadcast periodically, 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 including System Information 102 and other signals within cell 21. If RAN node 2 or 3 is in a C-RAN configuration, the DU (e.g., gNB-DU) may generate at least a part of the system information (e.g., MIB, SIB1). The DU may directly transmit the generated system information to UE1, or may transmit it to the CU (e.g., gNB-CU) so that the CU can transmit this to UE1 (via the DU).

[0033] In the example of FIG. 1, UE1 selects or reselects cell 21 of RAN node 2 and camps on cell 21. In other words, cell 21 is the serving cell of UE1. On the other hand, cell 31 is an adjacent (neighbour, neighbouring, adjacent) cell of serving cell 21 of UE1. Cell 21 and cell 31 may be operated in the same frequency band or in different frequency bands.

[0034] Not only cell 31, but also one or more other adjacent cells may exist around cell 21. Some or all of these other adjacent cells may be operated in the same frequency band as cell 21 or in different frequency bands.

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

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

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

[0038] The AS layer 208 starts the RRC connection establishment procedure or the RRC connection resume procedure in response to a request from the NAS layer 202 or spontaneously. For example, in response to receiving a PDU Session establishment request from an upper layer (i.e., the application layer 201), if the 5GS mobility management (5GMM) mode is 5GMM-IDLE, the NAS layer 202 starts a registration procedure or a service request procedure to transition to the 5GMM-CONNECTED mode and attempts to send an initial NAS message (e.g., a registration request message or a service request message) to the AMF. The initial NAS message from the NAS layer 202 triggers the AS layer 208 to establish an RRC connection between the UE1 and the RAN node 2. If the 5GMM mode is 5GMM-CONNECTED or 5GMM-CONNECTED with RRC inactive indication, the NAS layer 202 attempts to send a NAS message (e.g., a PDU SESSION ESTABLISHMENT REQUEST message, a UL NAS TRANSPORT message, a PDU SESSION MODIFICATION REQUEST, or a service request message) 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", the NAS layer 202 requests the AS layer 208 to transition to RRC_CONNETED (or resume the RRC connection) to send an uplink user data packet (i.e., Mobile Originated (MO) data).

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

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

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

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

[0043] The MAC layer 206 may follow the RACH partitioning of 3GPP Release 16. In the RACH partitioning of 3GPP Release 16, the UE can inform the gNB of the following information depending on which RACH preamble is used. - The selected Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) (or the 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, the MAC layer 206 supports additional RACH partitioning for Release 17 features. This enables the RAN node 2 to early identify the Release 17 features or feature combinations selected, desired, or intended by the UE1. For example, an RACH resource partition is set for each of all or a subset of the Release 17 features, and an RACH resource partition is further set 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. The feature combination includes, for example, at least two of RedCap, SDT, CovEnh, and Slicing. The term "feature" used hereinafter in this specification means any of these Release 17 features unless otherwise specified. Similarly, the term "feature combination" means a combination composed of at least two of these Release 17 features unless otherwise specified. A "feature combination" may be referred to as a "feature set" or a "set of features".

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

[0046] The SDT indication in the RACH is used to indicate the SDT to the network and request a larger third RACH message (MSG3) size. Alternatively, the SDT indication is used to indicate that the size of MSGA (the size of the data part of MSGA) is larger in the case of 2-step RA. Further, similar to the RACH in 3GPP Release 15 / 16, the size of MSG3 or MSGA may be of two types. In this case, the SDT indication in the RACH may further indicate the size of MSG3 or MSGA. SDT, also called SDT in inactive state, is one of the new features introduced in 3GPP Release 17. This enables UEs in the RRC_INACTIVE state to send infrequent and small data without requiring an RRC state transition.

[0047] The CovEnh indication in RACH is used to indicate the need for coverage enhancement and is used, for example, for the requirement of repetition of the 3rd RACH message (MSG3 in 4-step RA). The CovEnh indication may be binary information for indicating whether Msg3 PUSCH repetition is required. Alternatively, the CovEnh indication may indicate one of a plurality of coverage enhancement (CE) levels. The CovEnh indication may indicate one of two or more CE level groups (or CE modes). One CE level group or CE mode includes one or more CE levels. For example, the CE defined in 3GPP Release 14 supports up to 4 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, and a UE at CE level 3 enjoys relatively high path loss and low downlink received power.

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

[0049] Network slicing enables the creation of multiple virtualized logical networks on top of a physical network using Network Function Virtualization (NFV) technology and software-defined networking (SDN) technology. Each virtualized logical network is called a network slice or network slice instance, includes logical nodes and functions, and is used for specific traffic and signaling. The network slice may be a network slice provided by the core network (e.g., 5GC). The 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 Broad Band (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 allocate to UE1 a RAN slice and a radio slice associated with the network slice of the core network selected for UE1 to provide end-to-end network slicing to UE1. From the above, the Slicing indication at RACH may be information regarding the network slice of the core network, or information regarding the RAN or radio slice, or information regarding the end-to-end network slice.

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

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

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

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

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

[0055] In other implementations, the NAS layer 202 may determine or select a 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 FIG. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in FIG. 2.

[0057] FIG. 3 shows an example of the operation of UE1 regarding access attempts initiated by the NAS (NAS initiated access attempts). In step 301, the NAS layer 202 passes the information regarding the first feature to the AS layer 208, specifically, to the RRC layer 203. For example, the NAS layer 202 may send the information to the RRC layer 203 together with a request for transmitting an NAS message. The NAS layer 202 may send the information to the RRC layer 203 together with a request for a transition from RRC_IDLE or RRC_INACTIVE to RRC_CONNETED.

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

[0059] Alternatively, the information regarding the first feature may indicate one or more network slice groups intended by the NAS layer 202. Each of the one or more intended network slice groups may be identified by a slice group identifier (ID). The mapping of each network slice group to one or more network slices may be provided to the 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 the 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 is 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 the UE1 may determine the feature combination and indicate the determined feature combination to the MAC layer 206 of the UE1. Alternatively, the RRC layer 203 of the UE1 may determine one or more features to be included in the feature combination and indicate the determined one or more features to the MAC layer 206 of the UE1. The MAC layer 206 may further determine the necessary features and determine the feature combination.

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

[0063] In step 304, the AS layer 208 performs random access preamble transmission using the selected random access resource. Specifically, the MAC layer 206 requests the PHY layer 207 to perform preamble transmission using the selected random access resource.

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

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

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

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

[0068] According to the operation of the UE1 described with reference to FIG. 3 or FIG. 4 or both, the AS layer 208 can determine a feature combination including features related to the information (or state, or function) managed by the NAS layer 202. Therefore, this can provide an interaction between the NAS layer 202 and the AS layer 208 of the UE1 for the determination of the feature combination.

[0069] Note that in step 303 of FIG. 3 or step 405 of FIG. 4, if the set of random access resources associated with the feature combination is not set (or not available) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may notify the NAS layer 202 of a failure without performing a random access preamble transmission. 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 any of the fallback operations described in detail in the following third or fourth embodiments.

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

[0071] FIG. 5 shows a solution different from that of FIG. 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 the information to the RRC layer 203 together with a request for sending an NAS message. The NAS layer 202 may send the information to the RRC layer 203 together with a request for transition from RRC_IDLE or RRC_INACTIVE to RRC_CONNETED. The feature combination may be a combination of Release 17 features. Specifically, the feature combination may include at least two of RedCap, SDT, CovEnh, and Slicing.

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

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

[0074] In step 503, the AS layer 208 performs random access preamble transmission using the selected random access resource. Specifically, the MAC layer 206 requests the PHY layer 207 to perform preamble transmission using the selected random access resource.

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

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

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

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

[0079] In step 502 of FIG. 5 or step 606 of FIG. 6, if the set of random access resources associated with the feature combination is not set (or not available) in the serving cell (i.e., cell 21), the AS layer 208 (RRC layer 203) may notify the NAS layer 202 of a failure without performing a random access preamble transmission. 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 any of the fallback operations described in detail in the following third or fourth embodiments.

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

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

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

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

[0084] Note that UE1 (MAC layer 206) may select between a Normal Uplink (NUL) carrier and a Supplementary Uplink (SUL) carrier prior to random access resource selection. The SUL carrier 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 NUL carrier and the SUL carrier as the uplink carrier based on the downlink measurement results. For example, UE1 may operate in the same manner as the selection between the 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 to perform the random access procedure. Otherwise, UE1 may select the NUL carrier to perform the random access procedure.

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

[0086] If it is YES in step 701, UE1 (MAC layer 206) selects a random access resource from the first set (step 702).

[0087] If it is NO in step 701, UE1 (MAC layer 206) selects a random access resource from the second set of random access resources associated with the feature subset included in the selected feature combination (step 703). The feature subset may be referred to as a subset of features, a feature sub - combination, or a sub - combination of features. The feature subset includes 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. The feature subset may be one or more features supported (or executable) in cell 21. UE1 may select a feature subset to be prioritized or a feature subset with high necessity (or importance). 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, the MAC layer 206 of UE1 performs a random access preamble transmission using the selected random access resource. Specifically, the MAC layer 206 of UE1 requests the PHY layer 207 to transmit a random access preamble (RACH preamble) on the selected RACH resource.

[0089] When performing the fallback operations in steps 703 and 704, the AS layer 208 of UE1 may notify the NAS layer 202 of a random access failure corresponding to the originally intended feature combination or a fallback to a feature subset. Further or alternatively, if the feature subset is also not available in step 703, the AS layer 208 may notify the NAS layer 202 of a random access failure corresponding to the originally intended feature or feature combination. In this case, the AS layer 208 may notify the NAS layer 202 of the failure of the (most) prioritized feature among the feature combinations. Alternatively, the AS layer 208 may notify the NAS layer 202 of a failure regarding a feature for which it is not allowed to determine the necessity or feasibility of executing the function by the feature (e.g., MAC layer 206) in the AS layer 208.

[0090] According to the operation of UE1 described with reference to FIG. 7, if cell 21 does not provide a RACH resource set associated with a feature combination selected, desired, or intended by UE1, UE1 selects a RACH resource for random access to cell 21 from among alternative RACH resource sets associated with a feature subset included in the feature combination and provided by cell 21. This operation of UE1 allows cell 21 or RAN node 2 to provide only a plurality of 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 the fragmentation of random access resources.

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

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

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

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

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

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

[0097] If the answer is YES in step 801, UE1 (MAC layer 206) selects a random access resource from the first set (step 1102).

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

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

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

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

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

[0103] This embodiment relates to the handling of features and feature combinations selected, desired, or intended by UE1. The features can be classified into at least two types. In the first type, the MAC layer 206 of UE1 determines the necessity (or possibility) of executing the feature based on information or conditions predetermined by itself. Additionally or alternatively, the MAC layer 206 may make the above determination based on information received or specified from an upper layer (e.g., RRC layer 203) of UE1. In this type, when the MAC layer 206 of UE1 determines that at least one feature of the selected, desired, or intended feature combination does not need to be executed (or cannot be executed), the MAC layer 206 may change the content (i.e., the included features) of the feature combination so as to select a RACH resource for the remaining features or feature combination excluding the said feature. In other words, the MAC layer 206 may select a feature subset excluding the feature that does not need to be executed (or cannot be executed). In this case, the MAC layer 206 may notify the RRC layer 203 of the determination result (e.g., information on the feature combination to be executed, information on the excluded feature).

[0104] The second type is such that the MAC layer 206 of the UE1 does not or must not determine the necessity of executing its features (or whether the execution of its features is possible). In this type, the RRC layer 203 of the UE1 determines the necessity of executing its features (or whether the execution of its features is possible) and notifies the necessary information to the MAC layer 206. The determination by the RRC layer 203 may be made based on one or both of the UE capability of the UE1 and the predetermined information held by the RRC layer 203. Further or alternatively, the RRC layer 203 may make the above determination based on the information received or specified from a higher layer of the UE1 (e.g., the NAS layer 202). The MAC layer 206 selects a RACH resource corresponding to the feature or the feature combination including the feature. If the MAC layer 206 determines that there is no RACH resource corresponding to the feature, it may report a failure indication of RACH resource selection to the RRC layer 203. On the other hand, if the MAC layer 206 determines that there is no RACH resource corresponding to the feature combination including the feature, the MAC layer 206 excludes any one or more features corresponding to the first type from the feature combination and selects a RACH resource corresponding to a feature subset including the features of the second type and the remaining one or more features corresponding to the first type. Alternatively, the MAC layer 206 may select a RACH resource corresponding only to the features of the second type. In other words, when it is necessary to select a feature subset from the feature combination, the MAC layer 206 may always include one or more features of the second type (e.g., RedCap) included in the feature combination in the feature subset. Then, the MAC layer 206 may adjust the number of features in the feature subset depending on whether to include the features of the first type included in the feature combination in the feature subset.

[0105] The feature combination selected, desired, or intended by UE1 may include only one of the above two types, or may include both types. When the feature combination includes both types, MAC layer 206 may preferentially consider the features of the second type. For example, MAC layer 206 may prioritize executing the features of the second type. MAC layer 206 may preferentially select RACH resources corresponding to the 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 FIG. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in FIG. 2.

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

[0108] UE1 (RRC layer 203) may consider a cell or frequency band that provides an individual preamble resource set for a feature or combination of features to have a higher priority than a cell or frequency band that does not provide such an individual preamble resource set, for the purpose of selecting a cell to camp on. According to this operation, UE1 can preferentially select, as a cell to camp on, a cell that provides an individual set of random access resources for a selected, desired, or intended feature or combination of features.

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

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

[0111] Figure 9 shows an example of the operation of UE1 in cell selection or reselection or both. In step 901, UE1 (RRC layer 203) starts a cell selection process or a cell reselection evaluation process. The cell selection process is started, for example, by the newly selected new PLMN or Stand-alone Non-Public Network (SNPN). The cell reselection evaluation process enables UE1, which is in RRC_IDLE or RRC_INACTIVE, to select a more suitable cell. When UE1 is in the Camped Normally state, UE1 tries to detect, synchronize with, and monitor the intra-frequency, inter-frequency, and inter-RAT cells (e.g., cell 21) indicated by the serving cell.

[0112] In step 902, the UE1 (RRC layer 203) selects or reselects a cell to camp on from one or more candidate cells, taking into account whether the candidate cell provides an individual set of random access resources for a feature or feature combination. As described above, the UE1 (RRC layer 203) may consider a cell or frequency band that provides an individual preamble resource set for a feature or feature combination to have a higher priority for selecting a cell to camp on than a cell or frequency band that does not provide the individual preamble resource set. In step 903, the UE1 camps on the selected or reselected cell. Note that the UE1 may receive system information (e.g., SIB1) notified in a candidate cell for cell (re)selection, and determine based on the received system information whether the candidate cell provides an individual set of random access resources for a feature or feature combination. Further or alternatively, the system information (e.g., SIB1) notified in the current cell (serving cell) may indicate whether they are provided in adjacent cells, and the 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, the UE1 can preferentially select a cell that supports random access based on Release 17 features or feature combinations in cell selection and cell reselection.

[0114] Similar to that described in the fifth embodiment, the feature combination selected, desired, or intended by UE1 may include only one of the above two types, or may include both types. When the feature combination includes both types, UE1 (RRC layer 203) may preferentially consider the features of the second type in cell selection or reselection. For example, the RRC layer 203 may consider a cell or frequency band in which the features of the second type (or a subset of features) are available to have a higher priority for selecting a cell to camp on than a cell or frequency band in which this is not available. According to this operation, UE1 can preferentially select a cell in which the features of the second type (or a subset of features) are available as a cell to camp on. Alternatively, the RRC layer 203 may consider a cell or frequency band that provides an individual preamble resource set for the features of the second type (or a subset of features) to have a higher priority for selecting a cell to camp on than a cell or frequency band that does not provide this. According to this operation, UE1 can preferentially select a cell that provides an individual preamble resource set for the features of the second type (or a subset of features) 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 FIG. 1. The protocol stack of the control plane of UE1 may be the same as the example shown in FIG. 2.

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

[0117] In this embodiment, UE1 (RRC layer 203) considers a cell that supports the intended network slice and provides an individual set of random access resources for Release 17 features or feature combinations to have a higher priority for selecting a cell to camp on than a cell that does not support the intended network slice or does not provide the individual set. The intended network slice is the network slice intended by the NAS layer 202 of UE1. The intended network slice may be specified by an S-NSSAI. The intended network slice may be an S-NSSAI included in the Configured NSSAI or an S-NSSAI included in the Allowed NSSAI. The NAS layer 202 may indicate the intended network slice group to the RRC layer 203. The intended network slice group may be specified by a slice group ID. The mapping of the network slice group to one or more network slices may be provided to UE1 (NAS layer 202) 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 the 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).

[0118] In one implementation, the AS layer 208 may select the most appropriate cell by a slice-based (or slice-group-based) cell (re)selection process and then execute 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 FIG. 10.

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

[0120] The selection of the first cell by the AS layer 208 may be performed, for example, as follows. · First step: Sort the slices in priority order starting from the slice with the highest priority. · Second step: Select slices from the sorted slice list in priority order. · Third step: Assign priorities to frequencies or frequency bands for the selected slices. The priorities of the frequencies or frequency bands are set by the network (e.g., RAN node 2, or AMF). · Fourth step: Perform downlink measurements in the same manner as in Releases 15 and 16 starting from the frequency (band) with the highest priority. · Fifth step: If the cell with the highest rank is suitable in terms of radio quality and supports the slice selected in the second step, select the cell as the first cell and exit the sequence. · Sixth step: If there are remaining frequencies, return to the fourth step. · Seventh step: If the end of the slice list has not been reached, return to the second step. · Eighth step: Perform legacy cell reselection, i.e., cell reselection in the same manner as in Releases 15 and 16.

[0121] Subsequently, 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 feature combinations. If the first cell is selected according to the sequence described in the previous paragraph, the RRC layer 203 may perform step 1002 after ending the sequence in the fifth step.

[0122] Specifically, the RRC layer 203 may (re)select, as the camping-on cell, a second candidate cell that is in the same frequency band as the first candidate cell selected in step 1001, meets a predetermined radio quality criterion, and provides an individual set of random access resources for the feature or feature combination. 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 the 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, the AS layer 208 may execute a cell (re)selection process to prioritize the availability of random access based on Release 17 features or feature combinations simultaneously with (or in parallel with) the slice-based (or slice-group-based) cell (re)selection process. This may be performed, for example, in the middle of 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 where the highest priority slice is available, the AS layer 208 (RRC layer 203) may prioritize the candidate cell that provides an individual set of random access resources for the feature or feature combination.

[0124] In yet other implementations, the AS layer 208 may select an appropriate cell by a cell (re)selection process that prioritizes the availability of random access based on Release 17 features or feature combinations, and then perform slice-based (or slice-group-based) cell (re)selection. For example, the AS layer 208 may preferentially select, as candidate cells, cells in which random access based on Release 17 features or feature combinations is available, and then perform slice-based (or slice-group-based) cell (re)selection.

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

[0126] Next, a configuration example of the UE1 and the RAN node 2 according to the above-described plurality of embodiments will be described below. FIG. 11 is a block diagram showing a configuration example of the UE1. A Radio Frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with a RAN node. The RF transceiver 1101 may include a plurality of transceivers. The analog RF signal processing performed by the RF transceiver 1101 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1101 is coupled to an antenna array 1102 and a baseband processor 1103. The RF transceiver 1101 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1103, generates a transmission RF signal, and supplies the transmission RF signal to the antenna array 1102. Also, the RF transceiver 1101 generates a baseband reception signal based on the reception RF signal received by the antenna array 1102 and supplies this to the baseband processor 1103. The RF transceiver 1101 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, a plurality of phase shifters and a plurality of power amplifiers.

[0127] The baseband processor 1103 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of a transmission format (transmission frame), (d) channel coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT), etc. On the other hand, the control plane processing includes communication management of layer 1 (e.g., transmission power control), layer 2 (e.g., radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0128] For example, the digital baseband signal processing by the baseband processor 1103 may include signal processing of 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. Also, the control plane processing by the baseband processor 1103 may include processing of 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 referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1104 may include a plurality of processors (multiple processor cores). The application processor 1104 realizes various functions of the UE1 by executing a system software program (Operating System (OS)) read from the memory 1106 or a memory not shown and various application programs (for example, a call application, a WEB browser, a mailer, a camera operation application, a music playback application).

[0132] In some implementations, as shown by the dashed line (1105) in FIG. 11, the baseband processor 1103 and the application processor 1104 may be integrated on one chip. In other words, the baseband processor 1103 and the application processor 1104 may be implemented as one System on Chip (SoC) device 1105. The SoC device may also be referred to as a system Large Scale Integration (LSI) or a chipset.

[0133] Memory 1106 is a volatile memory, a non-volatile memory, or a combination thereof. Memory 1106 may physically include a plurality of independent memory devices. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is a mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. For example, memory 1106 may include an external memory device accessible from baseband processor 1103, application processor 1104, and SoC 1105. Memory 1106 may include an embedded memory device integrated within baseband processor 1103, within application processor 1104, or within SoC 1105. Further, memory 1106 may include the memory within a Universal Integrated Circuit Card (UICC).

[0134] Memory 1106 may store one or more software modules (computer programs) 1107 including instruction groups and data for performing the processing by UE1 described in the above-described multiple embodiments. In some implementations, baseband processor 1103 or application processor 1104 may be configured to perform the processing of UE1 described with reference to the drawings in the above-described embodiments by reading and executing the software module 1107 from memory 1106.

[0135] Note that the control plane processing and operations performed by UE1 described in the above-described embodiments can be realized by other elements excluding RF transceiver 1101 and antenna array 1102, that is, at least one of baseband processor 1103 and application processor 1104 and memory 1106 storing software module 1107.

[0136] FIG. 12 is a block diagram showing a configuration example of the RAN node 2 according to the above-described embodiment. Referring to FIG. 12, the RAN node 2 includes a Radio Frequency transceiver 1201, a network interface 1203, a processor 1204, and a memory 1205. The RF transceiver 1201 performs analog RF signal processing to communicate with UEs including the UE1. The RF transceiver 1201 may include a plurality of transceivers. The RF transceiver 1201 is coupled to the antenna array 1202 and the processor 1204. The RF transceiver 1201 receives modulation symbol data from the processor 1204, generates a transmission RF signal, and supplies the transmission RF signal to the antenna array 1202. Also, the RF transceiver 1201 generates a baseband reception signal based on the reception RF signal received by the antenna array 1202 and supplies this to the processor 1204. The RF transceiver 1201 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, a plurality of phase shifters and a plurality of power amplifiers.

[0137] The network interface 1203 is used to communicate with network nodes (e.g., SN2, as well as control nodes and transfer 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 a plurality of processors. For example, Processor 1204 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. Processor 1204 may include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and a precoder.

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

[0140] Memory 1205 may store one or more software modules (computer programs) 1206 containing instruction groups and data for performing the processing by RAN node 2 described in the above-described multiple embodiments. In some implementations, processor 1204 may be configured to perform the processing of RAN node 2 described in the above-described embodiments by reading and executing the software module 1206 from memory 1205.

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

[0142] As described with reference to FIGS. 11 and 12, each of the processors included in UE1 and RAN node 2 according to the above-described embodiments can execute one or more programs including instruction groups for causing a computer to perform the algorithms described with reference to the drawings. The program includes instruction groups (or software code) for causing a computer to perform one or more functions described in the embodiments when loaded into the computer. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or tangible storage medium includes 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 (registered trademark) disk, or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, the transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0143] <Other Embodiments> In the above embodiments, the "feature" may be a feature newly introduced in future 3GPP Release 18 or later. Similarly, in the above embodiments, the "feature combination" 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 additionally introduced in 3GPP Release 18. In one implementation, the feature MT-SDT may be distinguished from the feature MO-SDT, and an individual RACH resource set (or partition, or pool) may be set for the feature MT-SDT. In this case, the feature combination may include MT-SDT. The RAN node 2 may notify the UE1, via broadcast (e.g., SIB) or individual RRC signaling, whether MO-SDT and MT-SDT are distinguished in the RACH resource partition. Specifically, the random access configuration (e.g., RACH-Config) sent from the RAN node 2 to the UE1 may include a 1-bit flag (e.g., "mt-SDT") as an optional element. If the random access configuration includes the flag, the UE1 may use the RACH resource set for the feature (MO-)SDT for MT-SDT. On the contrary, if the random access configuration does not include the flag, the UE1 may check whether an individual RACH resource set (or partition, or pool) is set for MT-SDT, and if it is set, use the individual RACH resource set for the MT-SDT. If the random access configuration does not include the flag and no individual RACH resource set is set for MT-SDT, the UE1 may understand that MT-SDT is not supported. In this case, if the UE1 triggers MT-SDT, the UE1 may use the RACH resource set for the feature (MO-)SDT for MT-SDT, or use a RACH resource set similar to Release 15 and / or Release 16 for MT-SDT.

[0144] In the above embodiments, if the configuration (e.g., random access configuration), information, or field related to a feature (e.g., Release 17 feature) that UE1 does not support is included in the configuration received via RRC signaling (e.g., SIB), UE1 may operate so as not to ignore the value (or code point) of the configuration, information, or field.

[0145] For example, UE1 may recognize the size of the RACH resource set (or partition) of the feature or feature combination it desires based on the value of the first ra-PreambleStartIndex field related to the feature or feature combination it desires and the value of the second ra-PreambleStartIndex field of another feature or feature combination immediately following it. In this case, regardless of whether UE1 supports the feature or feature combination associated with the second ra-PreambleStartIndex field, the value of the second ra-PreambleStartIndex field shall not be ignored.

[0146] In some of the above embodiments, for a specific feature or a feature combination including it, UE1 may perform operations (or processes) different from those of the above embodiments. For example, regarding uplink carrier selection, for a specific feature (e.g., RedCap) or a feature combination including it, the uplink carrier to be selected (e.g., NUL carrier) may be predetermined (or specified in the specification). This is beneficial for fully utilizing the function of the feature or for considering the limitations in the function of the feature.

[0147] In some of the above embodiments, for a specific feature or a combination of features including the same, UE1 may perform operations (or processes) different from those in the above embodiments. For example, for a specific feature (e.g., Coverage enhancement), after uplink carrier selection, UE1 may determine the necessity of the feature (or whether to execute the feature). This is beneficial when the function of the feature depends on the result of uplink carrier selection.

[0148] Furthermore, the above-described embodiments are merely examples regarding the application of the technical idea obtained by the present inventor. That is to say, the technical idea is not limited to only the above-described embodiments, and it goes without saying that various modifications are possible.

[0149] For example, some or all of the above embodiments may be described as follows in the appended claims, but are not limited thereto.

[0150] (Appended Claim 1) At least one memory, At least one processor coupled to the at least one memory and configured to provide Non-Access Stratum (NAS) layer functions and Access Stratum (AS) layer functions, The NAS layer function is configured to pass information regarding a first feature to the AS layer function, The AS layer function, Determines a combination of features including the first feature derived from the information and one or more other features, Selects a random access resource from a first set of random access resources associated with the combination of features determined by the AS layer function, Performs a random access preamble transmission using the selected random access resource, Is configured as, A wireless terminal. (Appended Claim 2) The first feature is Slicing, The one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh). The wireless terminal according to appendix 1. (Appendix 3) The information regarding the first feature indicates one or more network slices intended by the NAS layer function, one or more network slice groups, or one or more network slice priority levels. The wireless terminal according to appendix 1 or 2. (Appendix 4) The information regarding the first feature indicates one or more Single Network Slice Selection Assistance Information (S-NSSAIs) to indicate the one or more intended network slices. The wireless terminal according to appendix 3. (Appendix 5) The AS layer function is configured to notify the NAS layer of a failure without transmitting a random access preamble if the first set is not available in the serving cell. The wireless terminal according to any one of appendices 1 to 4. (Appendix 6) The 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 a feature subset included in the feature combination Transmit a random access preamble using the random access resource selected from the second set And is configured to The wireless terminal according to any one of appendices 1 to 4. (Appendix 7) The 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, perform a random access preamble transmission with the random access resource selected from the third set, configured as, The wireless terminal according to any one of Appendices 1 to 4. (Appendix 8) Providing a Non-Access Stratum (NAS) layer function and an Access Stratum (AS) layer function, the NAS layer function passing information regarding a first feature to the AS layer function, the AS layer function determining a feature combination including the first feature derived from the information and one or more other features, the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination determined by the AS layer function, and the AS layer function performing a random access preamble transmission with the selected random access resource, comprising, A method performed by a wireless terminal. (Appendix 9) A program for causing a computer to perform a method for a wireless terminal, where the method includes providing a Non-Access Stratum (NAS) layer function and an Access Stratum (AS) layer function, the NAS layer function passing information regarding a first feature to the AS layer function, the AS layer function determining a feature combination including 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 with the selected random access resource; comprising; program. (Appendix 10) at least one memory; at least one processor coupled to the at least one memory and configured to provide a Non-Access Stratum (NAS) layer function and an Access Stratum (AS) layer function; The NAS layer function is configured to pass information indicating a feature combination to the AS layer function; The AS layer function selects a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function; performs random access preamble transmission with the selected random access resource; is configured to; wireless terminal. (Appendix 11) The feature combination includes Slicing and one or more other features; The wireless terminal according to Appendix 10. (Appendix 12) The one or more other features include at least one of Reduced Capability (RedCap), Small Data Transmission (SDT), and Coverage Enhancement (CovEnh); The wireless terminal according to Appendix 11. (Appendix 13) The one or more other features include at least Small Data Transmission (SDT); The wireless terminal according to Appendix 11 or 12. (Appendix 14) The information indicating the feature combination indicates one or more network slices intended by the NAS layer function, The wireless terminal according to any one of Appendices 10 to 13. (Appendix 15) The information indicating the feature combination includes one or more Single Network Slice Selection Assistance Information (S-NSSAI) to indicate the intended one or more network slices, The wireless terminal according to Appendix 14. (Appendix 16) If the first set is not available in the serving cell, the AS layer function is configured to notify the NAS layer of a failure without performing random access preamble transmission, The wireless terminal according to any one of Appendices 10 to 15. (Appendix 17) The AS layer function, 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 a feature subset included in the feature combination, Perform random access preamble transmission with the random access resource selected from the second set, is configured to, The wireless terminal according to any one of Appendices 10 to 15. (Appendix 18) The AS layer function, 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, Perform random access preamble transmission with the random access resource selected from the third set, is configured to, The wireless terminal according to any one of Supplementary Notes 10 to 15. (Supplementary Note 19) Providing a Non-Access Stratum (NAS) layer function and an Access Stratum (AS) layer function, the NAS layer function passing information indicating a feature combination to the AS layer function, the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function, and the AS layer function performing a random access preamble transmission using the selected random access resource, comprising A method performed by a wireless terminal. (Supplementary Note 20) A program for causing a computer to perform a method for a wireless terminal, the method comprising providing a Non-Access Stratum (NAS) layer function and an Access Stratum (AS) layer function, the NAS layer function passing information indicating a feature combination to the AS layer function, the AS layer function selecting a random access resource from a first set of random access resources associated with the feature combination indicated by the NAS layer function, and the AS layer function performing a random access preamble transmission using the selected random access resource, comprising A program. (Supplementary Note 21) at least one memory, at least one processor coupled to the at least one memory, When selecting or reselecting a cell to camp on from the at least one candidate cell, the at least one processor is configured to consider whether the candidate cell provides an individual set of random access resources for a selected, desired, or intended feature or combination of features. Wireless terminal. (Appendix 22) The at least one processor is configured to regard a cell or frequency band that provides the individual set as having a higher priority for selecting the camping cell than a cell or frequency band that does not provide the individual set. The wireless terminal according to Appendix 21. (Appendix 23) If the cell with the highest rank in the reception quality of the first frequency band does not provide the individual set and the cell with the second highest rank in the first frequency band provides the individual set, the at least one processor is configured to select the cell with the second highest rank as the cell to camp on. The wireless terminal according to Appendix 21 or 22. (Appendix 24) If the cell with the highest rank in the reception quality of the first frequency band does not provide the individual set and the cell with the highest rank in the reception quality of the second frequency band provides the individual set, the at least one processor is configured to select the cell with the highest rank in the second frequency band as the cell to camp on. The wireless terminal according to Appendix 21 or 22. (Appendix 25) If the first frequency band does not support the provision of the individual set and the second frequency band supports the provision of the individual set, the at least one processor is configured to select a cell in the second frequency band as the cell to camp on. The wireless terminal according to Appendix 21 or 22. (Appendix 26) The at least one processor is configured to consider a cell that supports an intended network slice, network slice group, or network slice priority level and provides the individual set to be of higher priority for selecting the camping cell than a cell that does not support the intended network slice or network slice group or does not provide the individual set. The wireless terminal according to any one of Appendices 21 to 25. (Appendix 27) The at least one processor selects a first candidate cell based on an intended network slice or network slice group, and selects, as the camping cell, a second candidate cell that is in the same frequency band as the first candidate cell, satisfies a predetermined radio quality criterion, and provides the individual set. is configured as The wireless terminal according to any one of Appendices 21 to 26. (Appendix 28) The feature is Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, and the feature combination includes at least two of RedCap, SDT, CovEnh, and Slicing. The wireless terminal according to any one of Appendices 21 to 27. (Appendix 29) When selecting or reselecting a camping cell from one or more candidate cells, considering whether a candidate cell provides an individual set of random access resources for a selected, desired, or intended feature or feature combination. A method performed by a wireless terminal. (Appendix 30) A program for causing a computer to perform a method for a wireless terminal, The method comprises considering whether a candidate cell provides an individual set of random access resources for a selected, desired, or intended feature or combination of features when selecting or reselecting a cell to camp on from one or more candidate cells. Program.

[0151] This application claims priority based on Japanese Patent Application No. 2021-171921 filed on October 20, 2021, and incorporates the entire disclosure thereof herein.

Description of Reference Numerals

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

Claims

Means for receiving, in a NAS layer from a core network, Non-Access Stratum (NAS) information related to a network slice and a network slice group; Means for receiving, in an Access Stratum (AS) layer, a setting related to random access prioritization associated with the network slice group; Means for providing, from the NAS layer to the AS layer, first information related to one or more intended network slices and second information related to the network slice group; Means for receiving system information including random access settings from a radio access network node; Means for determining, in the AS layer, whether a first set of random access resources associated with a feature or a feature combination selected, desired, or intended by a wireless terminal from among any one of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; Means for selecting a first random access resource from the first set and performing a random access preamble transmission using the selected first random access resource when the first set is available; Means for selecting a second random access resource from a second set of random access resources not associated with the feature or the feature combination and performing a random access preamble transmission using the selected second random access resource when the first set is not available; Means for determining, based on the setting related to the random access prioritization associated with the network slice group, whether random access prioritization is applicable to at least one of the one or more intended network slices, and executing the random access prioritization when applicable; Comprising; The second information includes a mapping between the network slice group and one or more network slices, and priority information associated with the network slice group. When the Slicing is included in the feature or the feature combination, random access resource selection is performed based on the network slice group. Wireless terminal. Claim 2 Before determining whether the first set is available, further comprising means for determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison between the RSRP of the downlink path loss criterion and rsrp-ThresholdSSB-SUL. The wireless terminal according to claim 1. Claim 3 A means for transferring Non-Access Stratum (NAS) information related to a network slice and a network slice group from a core network to a wireless terminal. A means for transmitting, in an Access Stratum (AS) layer, a setting related to random access prioritization associated with the network slice group to the wireless terminal. A means for transmitting system information including random access settings to the wireless terminal. A means for receiving a random access preamble from the wireless terminal. First information related to one or more intended network slices and second information related to the network slice group are provided from the NAS layer of the wireless terminal to the AS layer of the wireless terminal. If the AS layer of the wireless terminal determines that a first set of random access resources associated with a feature or combination of features selected, desired, or intended by the wireless terminal from among any one of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a combination of features including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available, the random access preamble is transmitted using a first random access resource selected from the first set. If the first set is not available, the random access preamble is transmitted using a second random access resource selected from a second set of random access resources not associated with the feature or the combination of features. The wireless terminal determines whether random access prioritization is applicable to at least one of the one or more intended network slices based on the setting regarding the random access prioritization associated with the network slice group, and if applicable, the wireless terminal performs the random access prioritization. The second information includes a mapping between the network slice group and one or more network slices and priority information associated with the network slice group. If Slicing is included in the feature or the combination of features, the wireless terminal performs random access resource selection based on the network slice group. Radio access network node. **Claim 4**: Receiving, in a NAS layer from a core network, Non-Access Stratum (NAS) information related to a network slice and a network slice group. Receiving, in an Access Stratum (AS) layer, a setting regarding random access prioritization associated with the network slice group. Providing, from the NAS layer to the AS layer, first information related to one or more intended network slices and second information related to the network slice group; Receiving, from a radio access network node, system information including random access configuration; Determining, in the AS layer, whether a first set of random access resources associated with a feature or a combination of features selected, desired, or intended by the wireless terminal, out of any one of Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a combination of features including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available; If the first set is available, selecting a first random access resource from the first set and performing a random access preamble transmission using the selected first random access resource; If the first set is not available, selecting a second random access resource from a second set of random access resources not associated with the feature or the combination of features and performing a random access preamble transmission using the selected second random access resource; and Determining whether random access prioritization is applicable to at least one of the one or more intended network slices based on the setting related to the random access prioritization associated with the network slice group, and if applicable, executing the random access prioritization; comprising; The second information includes a mapping between the network slice group and one or more network slices and priority information associated with the network slice group; If the Slicing is included in the feature or the combination of features, random access resource selection is performed based on the network slice group; A method performed by a wireless terminal. Claim 5 Before determining whether the first set is available, further comprising determining whether to use a Supplementary Uplink (SUL) carrier or a Normal Uplink (NUL) carrier based on a comparison between the downlink path loss criterion RSRP and rsrp-ThresholdSSB-SUL. The method according to claim 4.

6. Transferring Non-Access Stratum (NAS) information related to a network slice and a network slice group from a core network to a wireless terminal. Transmitting, in an Access Stratum (AS) layer, a setting related to random access prioritization associated with the network slice group to the wireless terminal. Transmitting system information including random access settings to the wireless terminal, and Receiving a random access preamble from the wireless terminal, comprising: First information related to one or more intended network slices and second information related to the network slice group are provided from the NAS layer of the wireless terminal to the AS layer of the wireless terminal. If the AS layer of the wireless terminal determines that a first set of random access resources associated with a feature or feature combination selected, desired, or intended by the wireless terminal from among Reduced Capability (RedCap), Small Data Transmission (SDT), Coverage Enhancement (CovEnh), or Slicing, or a feature combination including at least two of the RedCap, the SDT, the CovEnh, and the Slicing, is available, the random access preamble is transmitted using a first random access resource selected from the first set. If the first set is not available, the random access preamble is transmitted using a second random access resource selected from a second set of random access resources not associated with the feature or the feature combination. Whether random access prioritization is applicable to at least one of the one or more intended network slices is determined by the wireless terminal based on the setting regarding the random access prioritization associated with the network slice group, and if applicable, the random access prioritization is executed by the wireless terminal. The second information includes a mapping between the network slice group and one or more network slices, and priority information associated with the network slice group. When the Slicing is included in the feature or the feature combination, random access resource selection is executed by the wireless terminal based on the network slice group. A method performed by a radio access network node.

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