Cell Reselection Mechanism Interaction

Abstract

A network element of the wireless communication network is communicatively coupled to the user equipment and identifies a list of one or more features provided by the wireless communication network. Each feature on the list is associated with at least one of a service capability of the UE and a service requirement of the user equipment. The network element determines a priority among the one or more features related to cell reselection and assigns cell reselection priorities to the user equipment according to the priority, for example, by indicating the cell reselection priority or feature priorities and corresponding cell reselection mechanisms to the user equipment. The user equipment performs cell reselection by applying the cell reselection mechanism and cell reselection priority in accordance with the instructions of the network element.

Description

[Technical Field]

[0001] The present disclosure relates generally to mobile communication networks, such as 5G communication networks, and more particularly to cell reselection. [Background technology]

[0002] Network slicing is a new feature introduced by the Third Generation Partnership Program (3GPP) in New Radio (NR) mobile networks, also referred to as fifth generation (5G), to support different services using the same underlying mobile infrastructure. The current level of standardization at a general level is given by 3GPP Technical Specification 38.300.

[0003] Network slices may differ in either their service requirements, such as ultra-reliable low-latency communications (URLLC) and enhanced mobile broadband (eMBB), or in the tenants they serve.

[0004] A network slice is uniquely identified via an S-NSSAI (Single Network Slice Selection Assistance Information). Current 3GPP specifications allow a user equipment (UE) to be simultaneously connected and served by eight slices, corresponding to eight network slices identified by up to eight S-NSSAIs. See 3GPP TS38.300. On the other hand, a cell may support tens or even hundreds of slices; for example, in current specifications, a tracking area (TA) can support up to 1024 network slices. See 3GPP TS38.423.

[0005] The present disclosure is directed to improving cell reselection in a network environment through network slicing and slice-specific cell reselection mechanisms. Summary of the Invention

[0006] According to a first aspect, a method for cell reselection is provided. The method is performed by a network element of a wireless communication network. The network element is communicatively coupled to a user equipment (UE). The network element identifies a list of one or more functions provided by the wireless communication network. Each function on the list is associated with at least one of a service capability of the UE and a service requirement of the UE. The network element determines a priority among the identified functions related to cell reselection and assigns a cell reselection priority for the UE according to the priority.

[0007] In some embodiments, assigning a cell reselection priority for the UE includes indicating to the UE at least one of a cell reselection priority and a priority among identified functions related to cell reselection.

[0008] In some embodiments, assigning a cell reselection priority for the UE includes determining, for each of the identified functions, a single network slice selection assistance information, S-NSSAI, for the slice-specific cell reselection mechanism and a respective corresponding network slice access stratum group, NSAG, and indicating to the UE a cell reselection priority corresponding to the determined priority among the identified functions related to cell reselection.

[0009] In some embodiments, the cell reselection priority is indicated in the form of an NSAG priority or as a slice-specific cell reselection priority that is mapped to a corresponding NSAG.

[0010] In some embodiments, the network element transmits to the UE authorized network slice selection assistance information, the authorized NSSAI, including at least one S-NSSAI associated with the identified capability.

[0011] In some embodiments, the network element transmits to the UE configured network slice selection assistance information, the configured NSSAI, which includes at least one or more S-NSSAIs associated with the identified capabilities.

[0012] In some embodiments, identifying the list of capabilities includes identifying the list of capabilities based on a list of capabilities of interest received from the UE.

[0013] In some embodiments, the functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and sidelink communications.

[0014] In some embodiments, a function related to cell reselection is a function that has a corresponding cell reselection mechanism.

[0015] In some embodiments, assigning cell reselection priorities for the UEs includes signaling the cell reselection priorities to the UEs in order of priority via system information broadcast or dedicated signaling.

[0016] According to a further aspect, a network element of a wireless communication network is provided, the network element being communicatively coupled to a user equipment (UE) and configured to: identify a list of one or more functions provided by the wireless communication network, each function on the list being associated with at least one of a service capability of the UE and a service requirement of the UE; determine a priority among the identified functions related to cell reselection; and assign a cell reselection priority for the UE according to the priority.

[0017] In some embodiments, the network element is configured to assign a cell reselection priority for the UE by being caused to indicate to the UE at least one of the cell reselection priority and a priority among identified functions related to cell reselection.

[0018] In some embodiments, the network element is configured to determine, for each of the identified functions, a single network slice selection assistance information, S-NSSAI, for the slice-specific cell reselection mechanism and a respective corresponding network slice access stratum group, NSAG, and to indicate to the UE a cell reselection priority corresponding to the determined priority among the identified functions related to cell reselection.

[0019] In some embodiments, the cell reselection priority is indicated in the form of an NSAG priority or as a slice-specific cell reselection priority that is mapped to a corresponding NSAG.

[0020] In some embodiments, the network element is configured to transmit to the UE at least the allowed network slice selection assistance information, the allowed NSSAI, including one or more S-NSSAIs associated with the identified capability.

[0021] In some embodiments, the network element is configured to transmit to the UE configured network slice selection assistance information, the configured NSSAI, including at least one S-NSSAI associated with the identified capability.

[0022] In some embodiments, the network element is configured to identify the list of capabilities based on a list of capabilities of interest received from the UE.

[0023] In some embodiments, the functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and sidelink communications.

[0024] In some embodiments, a function related to cell reselection is a function that has a corresponding cell reselection mechanism.

[0025] In some embodiments, the network element is configured to assign cell reselection priorities for the UE by being caused to signal the cell reselection priorities to the UE in a prioritized order by system information broadcast or dedicated signaling.

[0026] According to another aspect, a method for cell reselection is provided. The method is performed by a user equipment (UE) communicatively coupled to a network element of a wireless communication network. The UE receives from the network element at least one of a cell reselection priority for one or more functions related to cell reselection and a priority among the identified functions related to cell reselection, each of the functions being provided by the wireless communication network and associated with at least one of a service capability of the UE and a service requirement of the UE. The UE applies one cell reselection mechanism of a plurality of cell reselection mechanisms based on the at least one of the cell reselection priority and the priority.

[0027] In some embodiments, a function related to cell reselection is a function that has a corresponding cell reselection mechanism.

[0028] In some embodiments, receiving at least one of the cell reselection priority and priority from the network element includes receiving the cell reselection priority or priority by way of a system information broadcast or dedicated signaling.

[0029] According to yet a further aspect, provided is a user equipment (UE) communicatively coupled to a network element of a wireless communication network. The UE is configured to receive, from the network element of the wireless communication network, at least one of a cell reselection priority for one or more functions related to cell reselection and a priority among the functions related to cell reselection, each of the functions provided by the wireless communication network and associated with at least one of a service capability of the UE and a service requirement of the UE. The UE is further configured to apply one cell reselection mechanism of a plurality of cell reselection mechanisms based on the at least one of the cell reselection priority and the priority.

[0030] In some embodiments, a function related to cell reselection is a function that has a corresponding cell reselection mechanism.

[0031] In some embodiments, the UE is configured to receive at least one of the cell reselection priority and priority by being caused to receive the cell reselection priority or priority by system information broadcast or dedicated signaling.

[0032] According to yet another aspect, a method for cell reselection performed by a user equipment (UE) is provided. The UE is communicatively coupled to a network element of a wireless communication network. The UE receives, from the network element, cell reselection priorities corresponding to determined priorities among one or more functions related to cell reselection, the cell reselection priorities including network slice access stratum groups, NSAG priorities, or slice-specific cell reselection priorities mapped to respective corresponding NSAGs, each of the functions being provided by the wireless communication network and associated with at least one of a service capability of the UE and a service requirement of the UE. The UE applies a slice-specific cell reselection mechanism based on the NSAG priorities or the slice-specific cell reselection priorities.

[0033] In some embodiments, the UE receives from a network element an authorized network slice selection assistance information, an authorized-NSSAI, that includes at least one single network slice selection assistance information, an S-NSSAI, associated with a capability for cell reselection.

[0034] In some embodiments, the UE receives from a network element a configured network slice selection assistance information, a configured-NSSAI, that includes at least one single network slice selection assistance information, an S-NSSAI, that is associated with a capability for cell reselection.

[0035] In some embodiments, the functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and sidelink communications.

[0036] In some embodiments, a function related to cell reselection is a function that has a corresponding cell reselection mechanism.

[0037] In some embodiments, receiving the cell reselection priorities from the network element includes receiving the cell reselection priorities via a system information broadcast or dedicated signaling.

[0038] According to yet a further aspect, a user equipment (UE) communicatively coupled to a network element of a wireless communications network is provided. The UE is configured to receive, from the network element, a cell reselection priority corresponding to a determined priority among one or more functions related to cell reselection, the cell reselection priority including a network slice access stratum group, an NSAG priority, or a slice-specific cell reselection priority mapped to a respective corresponding NSAG, each of the functions being provided by the wireless communications network and associated with at least one of a service capability of the UE and a service requirement of the UE. The UE is configured to apply a slice-specific cell reselection mechanism based on the NSAG priority or based on the slice-specific cell reselection priority.

[0039] In some embodiments, the UE is configured to receive from a network element an authorized network slice selection assistance information, an authorized-NSSAI, including at least one single network slice selection assistance information, an S-NSSAI, associated with a capability for cell reselection.

[0040] In some embodiments, the UE is configured to receive from a network element a configured network slice selection assistance information, a configured-NSSAI, including at least one single network slice selection assistance information, an S-NSSAI, associated with a capability for cell reselection.

[0041] In some embodiments, the functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and sidelink communications.

[0042] In some embodiments, the UE is configured to receive the cell reselection priorities by being caused to receive the cell reselection priorities by system information broadcast or dedicated signaling.

[0043] According to yet a further aspect, a method for slice-based cell reselection performed by a user device is presented. The user device is communicatively coupled to a network element of a wireless communication network. The user device receives at least one network slice access stratum group, NSAGs, and priority information for the at least one NSAG. The user device derives a reselection priority for slice-based cell reselection based on the at least one NSAG and the priority information for the at least one NSAG according to a predetermined scheme (e.g., TS38.304, Section 5.2.4.11). The user device does not modify the reselection priority due to other factors for cell reselection. That is, the user device applies the slice-based cell reselection mechanism even if one or more other factors for cell reselection other than slice-based cell reselection trigger cell reselection.

[0044] In some embodiments, the priority information for the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities for the corresponding one or more frequencies mapped to the at least one NSAG.

[0045] According to yet a further aspect, a user device supporting slice-based cell reselection is presented. The user device is communicatively coupled to a network element of a wireless communication network and comprises a processor and a memory having instructions, which, when executed by the processor, cause the user device to receive at least one network slice access stratum group, NSAGs, and priority information for the at least one NSAG, derive a reselection priority for slice-based cell reselection according to a predetermined scheme based on the at least one NSAG and the priority information for the at least one NSAG, and not modify the reselection priority due to other factors for cell reselection. That is, the user device applies the slice-based cell reselection mechanism even if one or more factors for cell reselection other than slice-based cell reselection trigger cell reselection.

[0046] In some embodiments, the priority information for the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities for the corresponding one or more frequencies mapped to the at least one NSAG.

[0047] According to yet a further aspect, a computer program comprises instructions that, when executed by at least one processor, perform any one of the foregoing method aspects and embodiments.

[0048] According to yet a further aspect, a computer-readable storage medium stores instructions that, when executed by at least one processor, cause a computer to perform any one of the foregoing method aspects and embodiments.

[0049] Various embodiments will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0050] [Figure 1] FIG. 1 is a visualization of a slice-based cell reselection procedure. [Figure 2] 1 is a schematic diagram of an exemplary communication system comprising a base station and a plurality of communication devices; [Figure 3] 1 is a schematic diagram of an exemplary mobile communication device. [Figure 4] FIG. 2 is a schematic diagram of an exemplary control device. [Figure 5] 1 is a flow diagram of a cell reselection procedure at a general level as described herein. [Figure 6] FIG. 1 is a diagram of a general message sequence representation of a cell reselection procedure as described herein. [Figure 7A] A diagram illustrating a slice-based cell reselection procedure based on S-NSSAI and / or NSAG priority related to one or more functions of a wireless communication network. [Figure 7B] A diagram illustrating a slice-based cell reselection procedure based on S-NSSAI and / or NSAG priority related to one or more functions of a wireless communication network. [Figure 8A] FIG. 1 illustrates a cell reselection procedure based on a prioritized list of one or more features provided by a wireless communication network. [Figure 8B] FIG. 1 illustrates a cell reselection procedure based on a prioritized list of one or more features provided by a wireless communication network. DETAILED DESCRIPTION OF THE INVENTION

[0051] As mentioned above, a network slice is identified by the S-NSSAI. The S-NSSAI may contain both the Slice Service Type (SST) and Slice Differentiator (SD) fields, with a total length of 32 bits, or may contain only the SST field portion, in which case the length of the S-NSSAI is 8 bits. See 3GPP TS23.501 and 3GPP TS23.003. The SST field may have standard and non-standard values. Values ​​0 to 127 belong to the standard SST range. For example, an SST value of 1 may indicate that the slice is suitable for 5G eMBB processing, a value of 2 may indicate that it is suitable for URLLC handling, etc. The SD is operator-defined only.

[0052] TS23.501 defines several types of NSSAIs: The allowed NSSAI is an NSSAI provided by the serving PLMN, for example, during the registration procedure, which indicates the S-NSSAI value that the UE may use in the serving PLMN for the current registration area; the configured NSSAI is provisioned in the UE applicable to one or more PLMNs; the pending NSSAI is provided by the serving PLMN during the registration procedure, which indicates the S-NSSAI for which a network slice-specific authentication and authorization procedure is pending; the requested NSSAI is provided by the UE to the serving PLMN during registration; and the subscribed S-NSSAI is based on the subscriber information that the UE is subscribed to for use in the PLMN.

[0053] A UE in RRC idle or RRC inactive state performs cell reselection to identify which cell the UE should camp on. Cell reselection is based on radio measurements and frequency priority. See 3GPP TS38.304. The UE may receive general frequency priority in system information, such as a system information block (SIB), and UE-specific priority in an RRC release message. The validity of the UE-specific priority may be limited by a timer.

[0054] According to 3GPP TS38.300, cell reselection criteria include measurements of the serving cell and neighboring cells. Intra-frequency reselection is based on cell ranking. Inter-frequency reselection is based on absolute priority, where the UE attempts to camp on the highest priority frequency available. A neighbor cell list (NCL) may be provided by the serving cell to handle specific cases of intra-frequency and inter-frequency neighboring cells. An exclusion list may be provided to prevent the UE from reselecting certain intra-frequency and inter-frequency neighboring cells. An allowed list may be provided to request the UE to reselect only certain intra-frequency and inter-frequency neighboring cells. Cell reselection may be speed dependent. Service-specific prioritization is possible.

[0055] Until 3GPP specification Release 17, cell reselection was network slice agnostic. However, the most suitable cell to be selected by a UE may depend on the slice the UE intends to use. Therefore, in Release 17, the slice-based cell reselection feature is introduced. Thus, slice-specific cell reselection information may be provided to facilitate a UE reselecting a cell that supports a specific slice. This slice-specific cell reselection mechanism enables a UE to reselect a cell on a frequency preferred by a network operator based on the most important network slice for the UE, based on slice-specific cell reselection priorities, but does not guarantee that the UE will reselect a cell that supports an authorized network slice or the most important network slice. If the UE reselects a cell that does not support an authorized network slice, the network can still redirect or handover the UE (in an RRC connected state) to a cell that is more suitable for the UE (e.g., in terms of network slice).

[0056] Additionally, the concept of slice groups (NSAGs - Network Slice AS Groups) is introduced to enable signaling optimization (especially regarding broadcasting) and promote security when publishing the S-NSSAI. The UE receives the mapping of slices to NSAGs using non-access stratum (NAS) signaling. The UE may also receive a per-NSAG priority (NSAG-specific cell reselection priority). Broadcasting of priority information for slice-specific cell reselection (e.g., slice-specific reselection priority) is performed per NSAG by a radio access network (RAN) node, such as a gNB (nsag-CellReselectionPriority, see 3GPP TS38.304 subclause 5.2.4.1 and 5.2.4.11).

[0057] An exemplary slice-specific cell reselection procedure is shown in FIG. 1. At 11, the UE 400 receives a general NSAG and corresponding priority (different from the cell reselection priority) from a network, such as the AMF 500, via a NAS message. At 12, the UE 400 receives the NSAG-specific cell reselection priority (frequency band priority per NSAG) from the RAN (e.g., the gNB 450) either via broadcast (a new SIB may be defined for this purpose) or dedicated signaling, such as an RRC release message that transitions the UE 400 from, for example, RRC connected to RRC idle. Cell reselection information received in dedicated signaling, such as an RRC release message, has priority over reselection information in a SIB. The gNB 450 managing the cell can broadcast either a list of allowed cells or a list of excluded cells per band per NSAG to support cell reselection in boundary areas of a tracking area at 13. Cells that are in the allowed list or not in the excluded list are assumed to support a given NSAG, provided that a list exists for the given NSAG and band. The UE 400 prioritizes frequency bands at 14 using the NSAG-specific cell reselection priorities (see TS 38.304 for further details on how the UE uses the priorities) and consequently either remains camped on the current serving cell or reselects another cell, also taking into account the cell reselection criteria described above.

[0058] Other cell reselection mechanisms, hereafter also referred to as function-specific cell reselection mechanisms, are defined in other Release 17 work items. See TS 38.304. One of these additional cell reselection mechanisms relates to high speed data networks (HSDN). When an HSDN-capable UE is in a high mobility state, the UE considers HSDN cells as the highest priority (i.e., higher than any other network-configured priority). When an HSDN-capable UE is not in a high mobility state, the UE always considers HSDN cells as the lowest priority (i.e., lower than any other network-configured priority).

[0059] A further cell reselection mechanism relates to Multicast Broadcast Service (MBS). If an MBS-capable UE receives or is interested in receiving an MBS session and can receive this MBS session by camping on the frequency on which the MBS session is provided, the UE may consider that particular frequency as the highest priority during the MBS session, as specified in TS 38.300. As long as an MBS-capable UE is receiving or interested in receiving an MBS session, the UE may consider a cell reselection candidate frequency on which the UE is unable to receive the MBS session as the lowest priority during an MBS broadcast session (see TS 38.300).

[0060] Yet further cell reselection mechanisms are related to sidelink communications from Pre-Release 17. If a UE is configured to perform both NR sidelink communications and V2X (vehicle-to-everything) sidelink communications, the UE may consider a frequency that provides both NR and V2X sidelink communications configurations as the highest priority. If a UE is configured to perform NR sidelink communications but not V2X communications, the UE may consider a frequency that provides an NR sidelink communications configuration as the highest priority. If a UE is configured to perform V2X sidelink communications but not NR sidelink communications, the UE may consider a frequency that provides a V2X sidelink communications configuration as the highest priority.

[0061] Currently, because a broadcast service can be received by all authorized UEs in a geographical area, there is no way for the UE to determine which slices to provide for the broadcast session, even if they are not included in the User Service Description (USD) of the MBS session. Note that this differs from a multicast service, where the UE must join the multicast session and therefore receive the associated S-NSSAI in the USD. For that reason, currently, the UE does not need to be configured with the S-NSSAI that the UE uses for the broadcast service in the authorized NSSAI.

[0062] For slice-specific cell reselection, the UE derives frequency reselection priorities based on the NSAGs and their corresponding cell reselection priorities. MBS allows the UE to consider MBS frequencies as the highest priority to enhance broadcast service continuity. Similarly, HSDN allows the UE to consider some frequencies as the highest priority. This also applies to sidelink communications.

[0063] Therefore, when a UE intends to use, for example, slice-specific cell reselection in addition to feature-specific cell reselection mechanisms such as MBS frequency prioritization, the UE behavior is currently non-specific. More specifically, there are several possible interpretations of what it means for an MBS frequency to be "considered the highest priority." For example, does the MBS take precedence over or act in addition to slice-specific priorities? Does the MBS frequency take precedence over slice-specific priorities? Does the MBS frequency take precedence over frequencies that are not mapped to any slice-specific priorities (i.e., frequencies with slice-specific priorities always have higher priority than MBS). Does the MBS frequency take precedence over frequencies that also have slice-specific priorities? Does the MBS frequency take precedence over frequencies that also have slice-specific priorities? Does the MBS take precedence over frequencies that allow MBS frequencies, and within those slices, are NSAG-specific priorities used to select the best frequency to camp on?

[0064] Therefore, an objective of this disclosure is to provide interworking between different cell reselection mechanisms available in Release 17, and potentially future cell reselection mechanisms.

[0065] Before describing those examples in detail, certain general principles of wireless communication systems and mobile communication devices will be briefly described with reference to Figures 2-4 to aid in understanding the technology underlying the described examples.

[0066] In a wireless communication system 100, such as that shown in FIG. 2, mobile communication devices, user devices, or user equipment (UE) 102, 104, 105, are provided wireless access via at least one base station (e.g., a next-generation NB, gNB), similar wireless transmitting and / or receiving node, or network node. The base station may be controlled or assisted by at least one appropriate controller apparatus to enable its operation and management of mobile communication devices communicating with the base station. The controller apparatus may be located within a radio access network (RAN) (e.g., the wireless communication system 100) or a core network (CN) (not shown) and may be implemented as one central apparatus, or its functions may be distributed across several apparatuses. The controller apparatus may be part of a base station and / or may be provided by a separate entity, such as a radio network controller (RNC) or central unit (CU), which typically implements higher network layers, such as Layer 3 protocols and / or radio resource control (RRC) protocols. In FIG. 2, controllers 108 and 109 are shown for controlling respective macro-level base stations 106 and 107. The base station controller may be interconnected with other control entities. The controller is typically provided with memory functionality and at least one data processor. The controller and functionality may be distributed among multiple control units. In some systems, the controller may additionally or alternatively be provided in the RNC.

[0067] In Figure 2, base stations 106 and 107 are shown as connected to a wider communications network 113 via a gateway 112. Further gateway functions may be provided to connect to other networks.

[0068] As used herein, the term “base station” has the full scope of its ordinary meaning and includes, at a minimum, a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system. The communication area (or coverage area) of a base station may be referred to as a “cell.” The base station and UE may be configured to communicate over a transmission medium using any of various radio access technologies (RATs), also referred to as wireless communication technologies, or telecommunications standards listed below. As shown in FIG. 2, one of the base stations may act as a “serving cell” for the UE, and the UE may also be able to receive signals from (and possibly be within communication range of) one or more other cells (which may be provided by the base station and / or any other base stations), which may be referred to as “neighboring cells.” As mentioned above, a base station may include multiple network nodes, such as an upper controller node that executes higher network layers, such as Layer 3 / RRC, and one or more lower nodes, such as a distributed unit (DU), that typically execute lower network layers, such as the physical layer (Layer 1, L1) and Layer 2 (L2). It should be noted that these multiple units may be geographically co-located or may be geographically separated to some extent.

[0069] The smaller base stations 116, 118, and 120 may also be connected to the network 113, for example, by a separate gateway function and / or through a controller in a macro-level station. The base stations 116, 118, and 120 may be pico- or femto-level base stations, etc. In this example, the stations 116 and 118 are connected through the gateway 111, while the station 120 is connected through the controller device 108. In some embodiments, the smaller stations may not be provided. The smaller base stations 116, 118, and 120 may be part of a second network, such as, for example, a wireless local area network (WLAN), and may be WLAN access points (APs). The communication devices 102, 104, 105 may access the communication system based on various access techniques, such as code division multiple access (CDMA) or wideband CDMA (WCDMA). Other non-limiting examples include time division multiple access (TDMA), frequency division multiple access (FDMA) and its variations such as interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), spatial division multiple access (SDMA), etc.

[0070] An example of a wireless communications system is the architecture being standardized by the Third Generation Partnership Project (3GPP). The latest 3GPP-based development is often referred to as the Long Term Evolution (LTE) of Universal Mobile Telecommunications System (UMTS) radio access technology. Various development stages of 3GPP specifications are referred to as releases. More recent developments of LTE are often referred to as LTE-Advanced (LTE-A). LTE (or LTE-A) utilizes a radio mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network known as the Evolved Packet Core (EPC). Base stations in such systems are known as evolved or enhanced Node Bs (eNBs) and provide E-UTRAN functions such as user plane packet data convergence, radio link control, medium access control, physical layer protocols (PDCP / RLC / MAC / PHY) and control plane radio resource control (RRC) protocol termination for communication devices. Other examples of wireless access systems include those provided by base stations in systems based on technologies such as WLAN and / or Worldwide Interoperable Microwave Access (WiMAX). A base station can provide coverage for an entire cell or a smaller radio service area. Core network elements include a mobility management entity (MME), a serving gateway (e.g., S-GW), and a packet gateway (P-GW).

[0071] An example of a suitable communication system is the 5G or NR concept. The network architecture of NR may be similar to that of LTE-A. Base stations in an NR system may be known as next-generation Node Bs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies, more precise quality of service (QoS) support, and some on-demand requirements for QoS to support user-perspective quality of experience (QoE). Network-aware services and applications, as well as service- and application-aware networks, may also bring about changes to the architecture. These are related to information-centric network (ICN) and user-centric content delivery network (UC-CDN) approaches. NR may use multiple-input, multiple-output (MIMO) antennas, more base stations or nodes than LTE (the so-called small cell concept), including macro sites working with smaller stations, and possibly also utilize various radio technologies for better coverage and increased data rates.

[0072] Future networks may utilize network function virtualization (NFV), a network architecture concept that proposes virtualizing network node functions into "building blocks," or entities that can be operationally connected or linked together to provide services. A virtualized network function (VNF) may include one or more virtual machines running computer program code using standard or generic types of servers instead of customized hardware. Cloud computing or data storage may also be utilized. In wireless communications, this may mean that node operations are performed, at least in part, within a server, host, or node that is operatively coupled to a remote radio head. It is also possible that node operations may be distributed among multiple servers, nodes, or hosts. It should also be understood that the distribution of work between core network operations and base station operations may differ from that of LTE or may even be absent.

[0073] An exemplary 5G Core Network (CN) includes functional entities. The CN is connected to the UE via a Radio Access Network (RAN). A User Plane Function (UPF), whose role is called a PDU Session Anchor (PSA), may be responsible for sending and receiving frames between the Data Network (DN) and a tunnel established via 5G for the UE to exchange traffic with the DN.

[0074] The UPF is controlled by a Session Management Function (SMF), which receives policies from a Policy Control Function (PCF). The CN may also include an Access and Mobility Function (AMF).

[0075] A possible (mobile) communication device 200 will now be described in more detail with reference to FIG. 3 , which shows a schematic, partial cross-sectional view. Such a mobile communication device 200 is often referred to as user equipment (UE), user device, or terminal device. A suitable mobile communication device 200 may be provided by any device capable of transmitting and receiving radio signals. Non-limiting examples include mobile stations (MS) or mobile devices such as mobile phones or what are known as “smartphones,” computers equipped with wireless interface cards or other wireless interface facilities (e.g., USB dongles), personal digital assistants (PDAs) or tablets equipped with wireless communication capabilities, or any combination thereof. Mobile communication devices 200 can provide communication of data to carry communications such as voice, electronic mail (email), text messages, multimedia, etc. Thus, users can be provided with and offered a multitude of services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services, or simply access to a data communication network system such as the Internet. Users can also be offered broadcast or multicast data. Non-limiting examples of content include downloads, television and radio programs, videos, advertisements, various alerts and other information.

[0076] In industrial applications, the communication device may be a modem built into an industrial actuator (e.g., a robotic arm) and / or a modem acting as an Ethernet hub that will act as a connection point for one or several connected Ethernet devices (the connection may be wired or wireless).

[0077] Communications device 200 is typically provided with at least one data processing entity 201, at least one memory 202, and possible other components 203 for use in software- and hardware-assisted execution of the tasks the wireless device is designed to perform, including controlling access to and communication with access systems and other communications devices. Data processing, storage, and other related controls may be provided on a suitable circuit board and / or within a chipset 204. A user may control the operation of communications device 200 by employing a suitable user interface, such as a keypad 205, voice commands, a touch-sensitive screen or pad, combinations thereof, or the like. A display 208, a speaker, and a microphone may also be provided. Additionally, communications device 200 may include appropriate connectors (either wired or wireless) for connecting other devices and / or external accessories, such as hands-free equipment, to the wireless communications device.

[0078] The communication device 200 can receive signals over an air or wireless interface 207 via suitable equipment for reception and can transmit signals via suitable equipment for transmitting wireless signals. In Figure 3, a transceiver unit is generally designated by block 206. The transceiver unit 206 can be provided, for example, by using radio components and an associated antenna arrangement. The antenna arrangement can be located external to the communication device 200 or can be located internally.

[0079] Communications device 200 may also, or alternatively, be configured to communicate using one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one or more mobile television broadcast standards (e.g., ATSC-M / H or DVB-H), and / or any other wireless communications protocol, as desired. Other combinations of wireless communications standards (including three or more wireless communications standards) are possible.

[0080] 3 includes a set of components configured to perform core functions. For example, the set of components may be implemented as a system-on-chip (SoC), which may include portions for various purposes. Alternatively, the set of components may be implemented as separate components or groups of components for various purposes. The set of components may be communicatively coupled (e.g., directly or indirectly) to various other circuits of the communications device 200.

[0081] The communications device 200 may include at least one antenna that communicates with a transmitter and a receiver (e.g., transceiver unit 206). Alternatively, the transmitting and receiving antennas may be separate. The communications device 200 may also include a processor (e.g., at least one data processing entity 201) configured to provide signals to the transmitter, receive signals from the receiver, and control functions of the communications device 200. The processor may be configured to control functions of the transmitter and receiver by providing control signaling to the transmitter and receiver via electrical leads. Similarly, the processor may be configured to control other elements of the communications device 200 by providing control signaling via electrical leads connecting the processor to other elements, such as a display (e.g., display 208) or memory (e.g., at least one memory 202). A processor may be embodied in various ways including, for example, a circuit, at least one processing core, one or more microprocessors with associated digital signal processors, one or more processors without associated digital signal processors, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits such as, for example, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc., or some combination thereof. Thus, in some examples, a processor may include multiple processors or processing cores.

[0082] Communications device 200 may be capable of operating with one or more air interface standards, communications protocols, modulation types, access types, etc. Signals transmitted and received by the processor may include signaling information according to applicable cellular system air interface standards and / or any number of different wired or wireless networking technologies, including, but not limited to, Wi-Fi, WLAN technologies, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, etc. Additionally, these signals may include speech data, user-generated data, user-requested data, etc.

[0083] For example, communication device 200 and / or the cellular modem therein may be capable of operating according to various third-generation (3G), fourth-generation (4G), fifth-generation (5G) communication protocols, e.g., Internet Protocol Multimedia Subsystem (IMS) such as Session Initiation Protocol (SIP), or 5G Beyond. For example, communication device 200 may be capable of operating according to 4G wireless communication protocols such as LTE-A, 5G, and the like, and similar wireless communication protocols that may be developed in the future.

[0084] The processor may include circuitry for executing the audio / video and logic functions of communication device 200. For example, the processor may include a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, etc. The control and signal processing functions of communication device 200 may be distributed among these devices according to their respective functions. The processor may additionally include an internal audio coder, an internal data modem, etc. Further, the processor may include functionality for operating one or more software programs, which may be stored in memory. Generally, the processor and stored software instructions may be configured to cause communication device 200 to perform operations. For example, the processor may be capable of operating a connectivity program, such as a web browser. The connectivity program may enable communication device 200 to send and receive web content, such as location-based content, according to protocols such as Wireless Application Protocol (WAP), Hypertext Transfer Protocol (HTTP), etc.

[0085] Communications device 200 may also include a user interface, including, for example, an earphone or speaker, a ringer, a microphone, a display, a user input interface, etc., which may be operably coupled to the processor. The display, as mentioned above, may include a touch-sensitive display, where a user can touch or gesture to make selections, input values, etc. The processor may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker, ringer, microphone, display, etc. The processor and / or user interface circuitry comprising the processor may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, e.g., software and / or firmware, stored in memory accessible to the processor, e.g., volatile memory, non-volatile memory, etc. Communications device 200 may also include a battery for powering various circuits associated with the mobile terminal, such as, for example, circuitry for providing mechanical vibrations as a detectable output. The user input interface may include devices that allow the communication device 200 to receive data, such as a keypad (e.g., keypad 206) and / or other input devices. The keypad may also be a virtual keyboard presented on a display or an externally connected keyboard.

[0086] Communication device 200 may also include one or more mechanisms for sharing and / or obtaining data. For example, communication device 200 may include a short-range radio frequency (RF) transceiver and / or interrogator, and thus may be able to share data with and / or obtain data from electronic devices according to RF techniques. Communication device 200 may also include other short-range transceivers, such as an infrared (IR) transceiver, a Bluetooth™ (BT) transceiver operating using Bluetooth™ wireless technology, a wireless universal serial bus (USB) transceiver, a Bluetooth™ low energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and / or any other short-range wireless technology. Communication device 200, and more specifically, the short-range transceiver, may be capable of transmitting and receiving data from electronic devices within the vicinity of the device, e.g., within 10 meters. The communication device 200, which includes a Wi-Fi or WLAN modem, may also be capable of transmitting and receiving data from electronic devices according to various wireless networking techniques, including WLAN techniques such as 6LoWPAN, Wi-Fi, Wi-Fi Low Power, IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and the like.

[0087] Communication device 200 may comprise memory, such as one or more subscriber identity modules (SIMs), one or more universal subscriber identity modules (USIMs), one or more removable user identity modules (R-UIMs), one or more embedded universal integrated circuit cards (eUICCs), one or more universal integrated circuit cards (UICCs), etc., that can store information elements related to mobile subscribers. In addition, communication device 200 may include other removable and / or fixed memory. Communication device 200 may include volatile memory and / or nonvolatile memory. For example, volatile memory may include random access memory (RAM), including dynamic and / or static RAM, on-chip or off-chip cache memory, etc. Non-volatile memory, which may be embedded and / or removable, may include, for example, read-only memory, flash memory, magnetic storage devices, e.g., hard disks, floppy disk drives, magnetic tape, optical disk drives and / or media, non-volatile random access memory (NVRAM), etc. Like volatile memory, non-volatile memory may include a cache area for temporarily storing data. At least a portion of the volatile and / or non-volatile memory may be incorporated into the processor. The memory may store one or more software programs, instructions, pieces of information, data, etc. that can be used by the device to perform the operations disclosed herein.

[0088] The memory may include an identifier, such as an International Mobile Equipment Identity (IMEI) code, that can uniquely identify communication device 200. In an exemplary embodiment, the processor may be configured to use computer code stored in the memory to cause the processor to perform the operations disclosed herein.

[0089] Some of the embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside on, for example, memory, a processor, or electronic components. In some exemplary embodiments, the application logic, software, or instruction set is maintained on any one of various conventional computer-readable media. In the context of this specification, a "computer-readable medium" may be any non-transitory medium or means capable of containing, storing, communicating, propagating, or transporting instructions for use by or cooperating with an instruction execution system, apparatus, or device, such as a computer or data processor circuitry; in the example shown in FIG. 3, the computer-readable medium may include a non-transitory computer-readable storage medium, which may be any medium capable of containing or storing instructions for use by or cooperating with an instruction execution system, apparatus, or device, such as a computer.

[0090] User equipment (UE) may include wireless or mobile devices, devices having a radio interface for interacting with a RAN (Radio Access Network), smartphones, in-vehicle devices, IoT devices, M2M devices, etc. Such UEs or devices may include at least one processor and at least one memory containing computer program code configured by the at least one processor to cause the device to perform at least certain operations, such as, for example, an RRC connection to the RAN. The UE is configured, for example, to generate messages (e.g., including a cell ID) to be transmitted over the air to the RAN (e.g., to reach and communicate with a serving cell). The UE can generate, send, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0091] The UE may have different states (e.g., according to 3GPP TS38.331V16.5.0 (June 2021) Sections 42.1 and 4.4, which are incorporated by reference). The UE may be in either an RRC connected state or an RRC inactive state, for example, when an RRC connection is established.

[0092] In the RRC connected state, the UE can store AS (Access Stratum) context, transfer unicast data to / from the UE, monitor the control channel associated with the shared data channel to determine whether data is scheduled for that data channel, provide channel quality and feedback information, and perform neighbor cell measurements and measurement reporting.

[0093] In some embodiments, communications device 200 (i.e., a UE or user device in a network) comprises a processor (e.g., at least one data processing entity 201) and a memory (e.g., at least one memory 202). The memory includes computer program code that causes communications device 200 to perform processing according to the methods described below.

[0094] FIG. 4 illustrates an exemplary embodiment of a communication system controller for coupling to and / or controlling a base station, an access system station such as a RAN node such as an eNB or gNB, a relay node or core network node such as an MME, S-GW, or P-GW, or a core network function such as an AMF / SMF, or a server or host. The method may be implemented within a single controller or across two or more controllers. The controller may be integrated with or external to a core network or RAN node or module. In some embodiments, a base station comprises a separate controller unit or module. In other embodiments, the controller may be another network element such as an RNC or spectrum controller. In some embodiments, a base station may have such a controller, as well as a controller provided in an RNC. The controller 300 may be configured to provide control over communications in the system's service area. The controller 300 comprises at least one memory 301, at least one data processing unit 302, 303, and an input / output interface 304. Via the interface, the controller 300 may be coupled to a receiver and a transmitter of the base station. The receiver and / or transmitter may be implemented as a radio front end or a remote radio head.

[0095] Generally, the controller 300 has an antenna for transmitting and receiving radio signals. A radio frequency (RF) transceiver module coupled to the antenna receives RF signals from the antenna, converts them to baseband signals, and transmits them to a processor (e.g., at least one data processing unit 302, 303). The RF transceiver also converts the received baseband signals from the processor, converts them to RF signals, and transmits them to the antenna. The processor processes the received baseband signals and invokes various functional modules to perform functions within the controller 300. A memory (e.g., at least one memory 301) stores program instructions and data for controlling the operation of the controller 300. In the example of FIG. 4, the controller 300 also includes a protocol stack and a set of control functional modules and circuits. A PDU session handling circuit handles PDU session establishment and modification procedures. A policy control module configures policy rules for the UE. A configuration and control circuit provides various parameters for configuring and controlling the UE for related functions, including mobility management and session management. Suitable processors include, by way of example, special purpose processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, ASICs, FPGA circuits, and other types of integrated circuits (ICs), and / or state machines.

[0096] In some embodiments, the controller 300 (i.e., a base station, a wireless transmitting and / or receiving point device, or a network node in the network) comprises a processor (e.g., at least one data processing unit 302, 303) and a memory (e.g., at least one memory 301). The memory includes computer program code that causes the controller 300 to perform processing according to the methods described below with reference to FIG. 5 et seq.

[0097] Referring now to FIG. 5, a method and network element for cell reselection are visualized at a general level. The network element forms part of a wireless communication network and may include multiple subcomponents, such as one or more RAN nodes and / or one or more core network nodes. The network element is communicatively coupled to a user equipment (UE), the cell reselection procedure of which will be controlled by the functions of the present invention. The network element may be a base station (e.g., a gNB). The network element identifies 51 a list of one or more functions provided by the wireless communication network, each function on the list relating to at least one of the UE's service capabilities and the UE's service requirements. The functions may be services supported and provided by the wireless network on a particular network slice, such as MBS, HSDN, sidelink, etc., as further described below. The functions may also be slice-specific cell reselection. In an embodiment, the network element determines such functions included in the list for which a corresponding cell reselection mechanism is defined in the wireless communication network and for which the UE has signaled interest and / or has capabilities. For example, if the network slicing feature is not supported by the UE and the UE may have signaled this through a prior capability negotiation, the network element may determine that network slicing should not be included in the list of features. On the other hand, if the UE has registered an MBS session and / or signaled interest in an MBS session, the network element includes MBS in the list of one or more features for cell reselection. The network element then determines a priority among the identified features related to cell reselection at 52. Thus, each of the identified features corresponds to a cell reselection mechanism, e.g., the feature MBS corresponds to MBS-specific cell reselection as introduced above. Thus, the prioritization of the features constitutes a prioritization of the associated or related cell reselections.

[0098] The network element then assigns the UE's cell reselection priority at 53 based on the priority. The assigning activity or function 53 may include multiple sub-activities or sub-functions, including transmissions or signaling to the UE. In some variations, the network element indicates to the UE at 54 at least one of the cell reselection priority and the priority among the identified functions related to cell reselection. As will be explained in further detail below, the priority among the listed functions related to cell reselection, or in other words, the priority among the cell reselection mechanisms corresponding to the identified and prioritized functions, may be indicated in the form of a sorted list in which functions that are elevated first are determined to have a higher priority than functions that are elevated later. Specific examples are provided further below with reference to Figures 7A and 7B and 8A and 8B.

[0099] In some variants, the network element determines, for each identified function, a single network slice selection assistance information (S-NSSAI) for the slice-specific cell reselection mechanism and its corresponding network slice access stratum group (NSAG). The network element then indicates to the UE at 55 a cell reselection priority corresponding to the determined priority among the identified functions related to cell reselection. The cell reselection priority may indicate a radio frequency priority mapped to an NSAG that can indicate to the UE a preference for selecting an available cell in a cell reselection procedure. More specifically, at 55, the network element indicates the cell reselection priority in the form of an NSAG priority or as a frequency slice-specific cell reselection priority mapped to the corresponding NSAG. The network element may also transmit to the UE an allowed NSSAI or a configured NSSAI that includes at least one or more of the determined S-NSSAIs associated with the identified function. Generally, information indicated by the network element to the UE to control the UE's cell reselection behavior may also be referred to hereinafter as cell reselection configuration information.

[0100] 6 is a further presentation of a cell reselection procedure according to the method of the present invention. The method may be performed by a UE 400 that is communicatively coupled to a first cell 401 of a wireless communication network, i.e., that is in an active, inactive, or idle state. From another perspective, the method is also performed by one or more network elements of the wireless communication network. On the network side, i.e., a network element of the wireless communication network, such as a gNB (more specifically, a node of the gNB, e.g., a central unit CU), transmits cell reselection configuration information to the UE 400. The UE 400, currently located in, connected to, or camped on the first cell 401 provided by the network element, receives the cell reselection configuration information from the network element of the wireless communication network at 403.

[0101] The cell reselection configuration information may include, among other things, network slice selection assistance information (NSSAI) associated with one or more features, such as the UE's service capabilities and / or services provided by the wireless communication network, and / or indicate a priority of multiple cell reselection mechanisms corresponding to the features. The cell reselection configuration information may include various information that controls and prioritizes the cell reselection behavior of the UE 400. To control the UE 400 to apply slice-specific cell reselection, the cell reselection information includes network slice selection assistance information (NSSAI). To control the UE 400 to apply one cell reselection mechanism from multiple cell reselection mechanisms corresponding to services or features provided by a network slice of the wireless communication network, such as multicast broadcast service (MBS), high-speed data network (HSDN), and / or sidelink communication, the cell reselection configuration information may indicate any one of the one or more features and a priority of the corresponding cell reselection mechanism. Both the NSSAI and cell reselection mechanism prioritization options control the UE to use, for example, slice-specific cell reselection mechanisms even if the UE also receives MBS / HSDN / sidelink transmissions and therefore may also apply cell reselection mechanisms corresponding to such transmissions.

[0102] Before signaling the cell reselection priority to the UE 400, the network element identifies the features to be considered for prioritization, as already mentioned above. For example, the UE 400 may have indicated prior capabilities and / or service interests, such as support for MBS, to the network. Thus, the UE 400 may have previously transmitted a list of features of interest to the network element to facilitate identification and prioritization of features and corresponding cell reselection mechanisms. The network element may then identify slice-specific cell reselection and MBS as features to be prioritized and determine the priority of these two features and / or the order of precedence between them. Based on the priority and / or precedence, the UE 400 is instructed to apply one of the cell reselection mechanisms, such as slice-specific cell reselection, instead of MBS-specific cell reselection, and reselect to a cell based on the cell reselection priority assigned or provided by the network element.

[0103] Thus, in embodiments, the cell reselection configuration information may include further information such as frequency prioritization related information, e.g., cell reselection priorities including lists of frequency-mapped NSAGs and corresponding cell reselection priorities of the frequencies, lists such as allowed lists, excluded lists, neighbor cell lists, service-specific prioritization information, etc. In some embodiments, the mapping between NSAGs and frequencies is provided along with the corresponding cell reselection priorities of the frequencies, while in other embodiments, the NSAG-to-frequency mapping is provided on top of a function-related S-NSSAI as an allowed or configured NSSAI, but the cell reselection configuration information does not include any priorities of the frequencies mapped to the NSAGs. In such embodiments, the UE 400 is enabled to reselect to a cell by slice-specific cell reselection based on the NSAG-specific priorities and the function-related S-NSSAI provided as an allowed or configured NSSAI.

[0104] Generally, cell reselection configuration information, such as cell reselection priority or prioritization among functions / mechanisms, may be transmitted in a single message, but may also be distributed across multiple messages. These messages may include NAS and AS / RAN messages. For example, part of the cell reselection configuration information may be transmitted by the core network via one or more NAS messages, while another part of the cell reselection configuration information is transmitted by one or more network elements of the radio access network of the wireless communication network. The cell reselection information may be broadcast to all UEs in the cell 401 and / or transmitted by dedicated signaling, e.g., via an RRC message such as an RRC release message that transitions the UE from an RRC connection to, e.g., an RRC idle state. Thus, the cell reselection information may be transmitted periodically or on-demand, e.g., in response to a UE request. Portions of the cell reselection information may be transmitted during the course of specific procedures specified by 3GPP technical specifications, such as a registration request with a requested NSSAI and a registration procedure including an allowed NSSAI (indicating an S-NSSAI corresponding to a capability requested or supported by the UE) or a configured NSSAI (indicating an S-NSSAI corresponding to a capability requested or supported by the UE). The cell reselection information provided to UE 400 may reflect UE capabilities and demands, such as the ability or interest to consume capabilities, such as for receiving MBS transmissions.

[0105] After receiving the cell reselection configuration information indicating the cell reselection priority, the UE 400 applies 404 one cell reselection mechanism from among the multiple cell reselection mechanisms, i.e., based on the NSSAI or the priority of the multiple cell reselection mechanisms as conveyed by the cell reselection configuration information. Thus, the UE 400 determines which cell reselection mechanism to apply from among the multiple cell reselection mechanisms based on the given cell reselection configuration information and possibly its own capabilities and current service demands, to determine whether to camp on 405 the current first cell 401 or reselect 406 to another second cell 402. It should be noted that the second cell 402 may belong to the same gNB or CU that controls the first cell 401 or to another gNB that controls the first cell 401.

[0106] Therefore, by prioritizing features supported by the wireless communication and determining slice-specific cell reselection priorities associated with the UE, the UE is also enabled to perform cell reselection for consuming features such as MBS by using a slice-based cell reselection mechanism, as opposed to using a cell reselection mechanism specific to a particular feature. In other words, if the UE supports slice-based cell reselection and receives NSAGs and their priorities from the NAS when the UE is in a normally camped state, the UE shall derive the reselection priority in accordance with TS38.304 Section 5.2.4.11 and shall not modify the reselection priority due to other factors (e.g., MBS frequency prioritization). That is, the user device applies the slice-based cell reselection mechanism even if one or more other factors for cell reselection other than slice-based cell reselection trigger cell reselection. In this regard, as explained above, it is up to the network to ensure the prioritization of services (e.g., MBS) when NSAG priorities are used.

[0107] 7A and 7B visualize a more specific variant of cell reselection according to the method described herein. More specifically, FIG. 7A and FIG. 7B relate to a variant in which a network element provides one or more NSSAIs indicating one or more cells that provide multicast broadcast service transmissions, high-speed data network transmissions, or sidelink communications. This can control the UE to utilize slice-specific cell reselection instead of applying a service- or function-related cell reselection mechanism, such as MBS-specific cell reselection, but still allow the UE 400 to reselect to a cell that provides a service, such as an MBS, that the UE 400 is interested in or desires to consume. On the other hand, by providing the UE 400 with an NSSAI and cell reselection / NSAG priority, the UE 400 can also be controlled to camp on or reselect to a cell that does not provide a service, such as an MBS, for any other reason, such as because a more important service may still be provided in a cell that does not provide an MBS. Thus, in general, provisioning the cell reselection configuration information in this manner causes the UE 400 to apply a slice-specific cell reselection mechanism regardless of any other potentially relevant or ongoing service transmissions, resulting in the UE 400 prioritizing cells for cell reselection based on the NSSAI provided by the network.

[0108] 7A, at 501, the UE 400 transmits a registration request message to the network, e.g., via the first cell 401 provided by a RAN element such as a gNB in ​​this example, for a core network element such as an Access and Mobility Management Function (AMF) 500 of the wireless communications network. The registration request message may include information of the requested NSSAI of the UE 400, which reflects the capabilities and services that the UE 400 potentially intends to use later.

[0109] Next, at 502, the network includes an S-NSSAI related to, for example, an ongoing MBS service as an allowed NSSAI (alternatively, as a configured NSSAI). This is based, for example, on UE capability information indicating that the UE 400 supports MBS. In other cases, a sidelink communication-related S-NSSAI and / or a high speed data network (HSDN)-related S-NSSAI may be included based on the UE capability and interest of the UE in those services. Information to be included by the network in response to a registration request message, such as a request accept message described below, may go beyond the UE capability information and be based, for example, on an indication that the UE 400 is about to initiate a service, such as a multicast broadcast service (MBS), and / or that there is an ongoing service transmission, such as a broadcast session, within the tracking area (TA), for example, within the cell 402.

[0110] A network element such as the AMF 500 returns a registration accept message to the UE 400 via the first cell 401 at 503. Accordingly, the UE 400 receives the registration accept message. As mentioned above, the registration accept message carries the allowed NSSAIs, including the MBS-related S-NSSAI. Additionally, the AMF 500 may also send a network slice access stratum group (NSAG) and corresponding priorities to the UE 400 via the first cell 401 at 504. The NSAG is defined within a TA and identifies a set of slices and priorities within the TA.

[0111] Upon receiving the information, the UE 400 is connected or active (at 505) within the cell 401 and can consume any service, such as an IP call or any other data communication.

[0112] After a period of time, e.g., due to UE 400 being inactive, service consumption ending, or other network-related reasons, the network may decide to change the status of UE 400 to an RRC idle state. Accordingly, the network (e.g., cell 1 401) may send an RRC release message to UE 400 at 506 to transition the UE's status from an RRC connected state to an RRC idle state. Additionally, the connection between the UE and cell 1 401 may be released.

[0113] At the same time, the network may transmit 507 NSAG-specific cell reselection priorities to provide the UE 400 with updated cell reselection configuration information to facilitate cell reselection in RRC idle or RRC inactive state. The NSAG-specific cell reselection priorities may be signaled, for example, by broadcast in SIB16 (e.g., FreqPriorityListNRSlicing with information element cellReselectionPriority or functionally similar information elements, see TS38.331). It should be noted that in some embodiments, only the NSAG for a particular frequency mapping is signaled without any priority indication (without the CellReselectionPriority information element).

[0114] In the RRC idle or RRC active state, the UE 400 typically performs cell reselection according to an established procedure, i.e., measurements of the radio conditions of the cell on which the UE 400 is camped and neighboring cells. At some point, the UE 400 performs cell reselection taking into account the current radio conditions and other information discussed above, including the S-NSSAI received at 503, the prioritized NSAG received at 504, and / or the NSAG-specific cell reselection priority received at 507, to reselect to another second cell or to remain camped on the current first cell 401. In the example of Figures 7A and 7B, the UE applies a slice-specific cell reselection mechanism at 508 according to the S-NSSAI received at 503, the prioritized NSAG received at 504, and the NSAG-specific cell reselection priority received at 508. Even if UE 400 receives cell reselection configuration information for other cell reselection mechanisms and such other cell reselection mechanisms trigger cell reselection, UE 400 does not modify the reselection priority due to other factors (e.g., MBS frequency prioritization) and such other cell reselection mechanisms. Rather, UE 400 performs cell reselection based on the unmodified reselection priority and camps on or reselects to a cell based on the aforementioned information received at 503, 504, and / or 508. In the use cases of Figures 7A and 7B, UE 400 does not need to consider such other cell reselection mechanisms because the slice-specific cell reselection configuration information at 502, 504, and / or 508 enables UE 400 to reselect to any cell that provides UE 400 with one or more functions related to services such as an MBS session, HSDN transmission, and / or sidelink communication.

[0115] In this regard, various situations may arise. For example, Figure 7A illustrates a case in which UE 400 receives a service announcement, such as an MBS service announcement (not shown in Figure 6), indicating that the service is provided on the frequency of second cell 402 (e.g., cell 2) rather than first cell 401 (e.g., cell 1). However, UE 400 applies an MBS-specific cell reselection mechanism, but instead utilizes the S-NSSAI received at 503, the NSAG received at 504, and the NSAG-specific cell reselection priority received at 508. In the example of Figure 7A, the S-NSSAI prioritizes first cell 401 over second cell 402, i.e., instructs UE 400 to stay on first cell 401. Thus, UE 400 does not prioritize the frequency of second cell 402, as it would have done in the case of MBS-specific cell reselection. Rather, the UE 400 uses slice-specific cell reselection and therefore does not reselect to the second cell 402 and camps on the first cell 401 at 509.

[0116] Another example based on signaling of S-NSSAI, NSAG, and NSAG-specific cell reselection priority is given in Figure 7B, where activities 501-508 correspond to those of Figure 7A. However, here the associated S-NSSAI indicates that slice-specific cell reselection should be applied, and the NSAG and NSAG-specific cell reselection priority indicates that the second cell 402 should be preferred. This can be based on information about the UE capabilities and services supported by, or to be provided by, the second cell 402. For example, the network may know that the UE 400 is MBS-capable and that the second cell 402 supports MBS, or that an MBS session is currently being broadcast in the second cell 402. Thus, the S-NSSAI provided at 503, the NSAG provided at 504, and the NSAG-specific cell reselection priority provided to the UE 400 at 508 may indicate a slice-specific preference for the second cell 402 compared to the first cell 401. Again, the UE 400 may have received, for example, an MBS service announcement at some point between activities 506 and 508 indicating that the MBS service is provided on the frequency of the second cell 402 rather than the first cell 401. Again, the UE 400 does not prioritize the frequency of the second cell 402 due to the MBS-specific cell reselection mechanism, but prioritizes the second cell 402 by applying slice-specific cell reselection at 508. As a result, the UE 400 reselects to the second cell 402 based on the slice-specific cell reselection mechanism and begins camping on the selected cell (e.g., the second cell) at 510.

[0117] After successful reselection to the second cell 402, the UE 400 may receive 511 an NSAG-specific cell reselection priority from the network via the second cell 402, for example, by SIB16. Additionally, because an MBS session is not provided in the first cell 401, the network may include the frequency of the first cell 401 in an "exclusion list" of its S-NSSAI. According to the "exclusion list," the UE 400 excludes the first cell 401 as a potential candidate for cell reselection and does not reselect to or camp on the first cell 401.

[0118] 7A and 7B, the network controls the UE 400 to apply slice-specific cell reselection by providing the UE 400 with slice-specific cell reselection configuration information that may or may not prioritize cells providing services such as MBS, HSDN, sidelink, etc., for the purpose of cell reselection. It should be noted that, in the examples of FIGS. 7A and 7B, MBS is mentioned as an example of a main service or function, but this is merely exemplary in nature and those skilled in the art will understand that the same may be applied to any other service using a corresponding cell reselection mechanism. The scenarios of FIGS. 7A and 7B can be summarized by the UE 400 receiving at least one network slice access stratum group, NSAG, and priority information for the at least one NSAG. The UE 400 derives a reselection priority for slice-based cell reselection according to a predetermined scheme based on the at least one NSAG and the priority information for the at least one NSAG, and the UE 400 does not modify the reselection priority due to other factors of cell reselection, such as MBS-related cell reselection configuration information received by the UE 400. As described above, the priority information of the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities for the corresponding one or more frequencies mapped to the at least one NSAG. It should be noted that the second cell 402 may belong to the same gNB or CU that controls the first cell 401, or to another gNB that controls the first cell 401.

[0119] In some embodiments, now referring to Figures 8A and 8B, the cell reselection configuration information indicates a priority of multiple cell reselection mechanisms. More specifically, in exemplary embodiments according to Figures 8A and 8B, the cell reselection configuration information indicates a priority of multiple cell reselection mechanisms and includes a sorted list of at least two of the multiple cell reselection mechanisms. The sorted list can indicate a relative priority between at least two of the multiple cell reselection mechanisms, for example, the first listed cell reselection mechanism has the highest priority, while the last listed cell reselection mechanism has the lowest priority among the listed cell reselection mechanisms.

[0120] The scenarios of Figures 8A and 8B may incorporate similar flows for activities 501-506, ultimately placing UE 400 in an RRC idle or RRC inactive state at 600. Generally, and similar to Figures 7A and 7B, UE 400 is assumed to support slice-specific cell reselection, but the UE may also be interested in receiving services provided by one or more cells of the communication network, such as sidelink / HSDN and broadcast services.

[0121] In the embodiment according to Figures 8A and 8B, a network element serving a first cell 401 signals 601 a list of one or more capabilities, or more generally, a list of one or more cell reselection mechanisms, in a prioritized manner. This controls the UE to use the signaled highest priority applicable cell reselection mechanism when performing cell reselection. The one or more capabilities and one or more corresponding cell reselection mechanisms signaled to the UE 400 may each take the form of a list. For example, if the list is configured as {MBS, sidelink, HSDN, slice}, the list indicates that MBS-specific cell reselection has the highest priority and slice-specific cell reselection has the lowest priority. For example, a UE 400 with capabilities and interest in MBS services would then apply the MBS-specific cell reselection mechanism when performing a cell reselection procedure. Another UE 400 interested in sidelink communication but not an MBS session would prioritize cells using the cell reselection mechanism defined for the sidelink. Generally, the UE 400 applies a cell reselection mechanism in 602 according to the priority list received in 601 .

[0122] This list of prioritized capabilities or cell reselection mechanisms can be provided to the UE through an RRC release message when the UE transitions from an RRC connected to an RRC idle state. Additionally or alternatively, the list may be broadcast by system information such as SIB16.

[0123] Similar to Figures 7A and 7B, several scenarios may be assumed in the embodiments according to Figures 8A and 8B. In the example of Figure 8A, the list signaled in 601 may be configured as {slice, sidelink communication, HSDN, MBS}. Thus, the UE 400 may apply slice-specific cell reselection. As a result, in 603, the UE 400 uses a slice-specific cell reselection mechanism that causes the UE to stay on the current first cell 401. Thus, as indicated by arrow 603 in Figure 8A, the UE 400 continues to camp on the first cell 401.

[0124] 8B, in which the network signals 601 a cell reselection mechanism priority list indicating {MBS, sidelink, HSDN, slice}. UE 400 may receive an MBS service indication indicating that an MBS session is to be initiated in the second cell 402 at some point after 602. At this time, UE 400 interested in the MBS session prioritizes MBS frequencies based on the MBS-specific cell reselection mechanism because the cell reselection mechanism priority list received in 601 attributes a higher priority to MBS than slice-specific cell reselection. UE 400 then applies MBS-specific cell reselection based on the list in 601 and then reselects to the second cell 402 to participate in the MBS session at 604.

[0125] It should be noted that the second cell 402 may belong to the same gNB or CU that controls the first cell 401, or to another gNB that controls the first cell 401. As mentioned above, in an embodiment, the aforementioned cell reselection mechanism is applied when the UE is in an RRC idle state. Alternatively or additionally, in an embodiment, the aforementioned cell reselection mechanism is applied when the UE is in an RRC disconnected state.

[0126] From the perspective of a user equipment (UE), the present disclosure can also be characterized by the following points.

[0127] Point 1: A method for cell reselection, the method being performed by a user equipment (UE) communicatively coupled to a network element of a wireless communication network, the method including: receiving cell reselection configuration information from the network element of the wireless communication network, the cell reselection configuration information including network slice selection assistance information (NSSAI) related to service capabilities of the UE and services provided by the wireless communication network, and indicating a priority of a plurality of cell reselection mechanisms; and applying one cell reselection mechanism of the plurality of cell reselection mechanisms based on the NSSAI or the priority of the plurality of cell reselection mechanisms.

[0128] Point 2: The method described in Point 1, wherein the multiple cell reselection mechanisms include slice-specific cell reselection, multicast broadcast service-specific cell reselection, high-speed data network-specific cell reselection, and sidelink communication-specific cell reselection.

[0129] Point 3: The method according to point 2, wherein the NSSAI indicates one or more cells providing multicast broadcast service transmission, high speed data network transmission or sidelink communication.

[0130] Point 4: The method according to point 3, further comprising: in a UE, receiving, from a network element of a wireless communications network, an NSSAI indicating one or more cells that provide a multicast broadcast service transmission, a high-speed data network transmission, or a sidelink communication; receiving a service announcement indicating that the multicast broadcast service transmission, the high-speed data network transmission, or the sidelink communication is provided in at least one of the one or more cells indicated by the NSSAI; and applying, based on the NSSAI, a slice-specific cell reselection mechanism; and reselecting to one of the at least one cells indicated by the NSSAI based on the slice-specific cell reselection mechanism.

[0131] Point 5: The method according to point 2, wherein the NSSAI indicates one or more cells that do not provide multicast broadcast service transmission, high speed data network transmission or sidelink communication.

[0132] Point 6: The method of point 5, further comprising: in the UE, receiving, from a network element of the wireless communications network, an NSSAI indicating one or more cells that do not provide multicast broadcast service transmission, high speed data network transmission, or sidelink communication; receiving a service announcement indicating that multicast broadcast service transmission, high speed data network transmission, or sidelink communication is provided in at least one of the one or more cells indicated by the NSSAI; and applying a slice-specific cell reselection mechanism based on the NSSAI; and reselecting to one of the at least one cell indicated by the NSSAI based on the slice-specific cell reselection mechanism.

[0133] Point 7: The method described in point 2, wherein the cell reselection configuration information indicating the priority of the multiple cell reselection mechanisms includes a sorted list of at least two of the multiple cell reselection mechanisms, and the sorted list indicates a relative priority between the at least two of the multiple cell reselection mechanisms.

[0134] Point 8: The method according to point 7, wherein the priority indicates a priority of the slice-specific cell reselection mechanism that is higher than at least one other cell reselection mechanism among the plurality of cell reselection mechanisms, and the method further includes receiving, at the UE, a service announcement indicating that a multicast broadcast service transmission, a high speed data network transmission or a sidelink communication is provided in at least one cell of the wireless communications network, and applying the slice-specific cell reselection mechanism based on the priority.

[0135] Point 9: The method of point 7, wherein the priority indicates a priority of a first cell reselection mechanism among the plurality of cell reselection mechanisms that is higher than a slice-specific cell reselection mechanism, and the method further includes: receiving, at the UE, a service announcement indicating that a service transmission corresponding to the first cell reselection mechanism is provided in at least one cell of the wireless communication network; and applying, based on the priority, the first cell reselection mechanism and reselecting to one cell of the one or more cells of the wireless communication network to receive the service transmission.

[0136] Point 10: The method of point 7, wherein the priority indicates a priority of a first cell reselection mechanism among the plurality of cell reselection mechanisms that is higher than a second cell reselection mechanism among the plurality of cell reselection mechanisms, and thus higher than a slice-specific cell reselection mechanism, and the method further includes: receiving, at the UE, a service announcement indicating that a service transmission corresponding to the second cell reselection mechanism is provided in at least one cell of the wireless communication network; and applying the second cell reselection mechanism based on the priority and reselecting to one cell of the one or more cells of the wireless communication network to receive the service transmission.

[0137] Point 11: The method according to any one of points 1 to 10, wherein the cell reselection configuration information is received through system information and / or dedicated signaling.

[0138] Point 12: The method according to any one of points 1 to 11, wherein the cell reselection configuration information includes an allowed list of serving cells or an excluded list of non-serving cells.

[0139] Point 13: The method according to any one of points 1 to 12, wherein the UE is in an idle state or an inactive state when applying a cell reselection mechanism based on the cell reselection configuration information.

[0140] Point 14: The method according to any one of points 1 to 13, including receiving at least one network slice access stratum group, an NSAG, and priority information of the at least one NSAG, and deriving a reselection priority for slice-based cell reselection according to a predetermined scheme based on the at least one NSAG and the priority information of the at least one NSAG, wherein the UE does not modify the reselection priority due to other factors of cell reselection.

[0141] 16. The method according to point 15, wherein the priority information of the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities of the corresponding one or more frequencies mapped to the at least one NSAG.

[0142] Corresponding points can be listed for device and user equipment categories.

[0143] Corresponding points may be described that specify an apparatus, such as user equipment, that is configured to perform these method points. For example, the apparatus may comprise a processor and a memory that stores program instructions that, when executed by the processor, perform the aforementioned UE-related method points.

[0144] It should be understood that the apparatus described herein may comprise or be coupled to other units or modules, such as radio components or radio heads, used in or for transmitting and / or receiving. Although the apparatus is described as one entity, the different modules and memories may be embodied in one or more physical or logical entities.

[0145] It is noted that although the embodiments are described in the context of LTE and 5G NR, similar principles apply in the context of other networks and communication systems in which fast connection re-establishment is required to be enforced. Thus, although particular embodiments are described above with reference to particular exemplary architectures of wireless networks, technologies and standards by way of example, the embodiments may be applied to any other suitable form of communication system other than those illustrated and described herein.

[0146] While the above describes exemplary embodiments, it is also noted herein that there are several variations and modifications that can be made to the disclosed solution without departing from the scope of the present disclosure.

[0147] In general, various exemplary embodiments may be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects of the present disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device, although the present disclosure is not limited thereto. While various aspects of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representation, it will be understood that these blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special-purpose circuits or logic, general-purpose hardware or controller or other computing device, or some combination thereof.

[0148] Exemplary embodiments of the present disclosure may be implemented by computer software executable by a data processor of a mobile device, such as in a processor entity, or by hardware, or a combination of software and hardware. Computer software or programs, also referred to as program products, including software routines, applets, and / or macros, may be stored on any device-readable data storage medium and include program instructions for performing specific tasks. A computer program product may include one or more computer-executable components configured to perform embodiments when the program is run. The one or more computer-executable components may be at least one software code or portion thereof.

[0149] Furthermore, in this regard, it should be noted that any block of a logic flow, such as that in the figures, may represent a program step, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. Software may be stored on physical media, such as memory chips or blocks embodied within a processor, magnetic media such as hard disks or floppy disks, and optical media, e.g., DVDs and their data variants, CDs, etc. Physical media are non-transitory media.

[0150] The memory may be of any type suitable for the local technology environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed and removable memory, etc. The data processor may be of any type suitable for the local technology environment and may include, by way of non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an FPGA, a gate level circuit, and a processor based on a multi-core processor architecture.

[0151] Exemplary embodiments of the present disclosure may be practiced in a variety of components, such as integrated circuit modules. The design of integrated circuits is, for the most part, a highly automated process. Complex and powerful software tools are available for translating logic-level designs into semiconductor circuit designs that are easily etched and formed on semiconductor substrates.

[0152] The above description has provided a complete and informative description of exemplary embodiments of the present disclosure, by way of non-limiting example. However, various modifications and adaptations may become apparent to those skilled in the art in light of the above description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of the present disclosure will still fall within the scope of the present disclosure as defined in the appended claims. In fact, further embodiments exist that include combinations of one or more of the embodiments with any of the other embodiments described above.

Claims

1. 1. A method for cell reselection, the method being performed by a network element of a wireless communications network, the network element being communicatively coupled to a user equipment, UE, the method comprising: identifying a list of one or more features provided by the wireless communications network, each feature on the list associated with at least one of a service capability of the UE and a service requirement of the UE; determining a priority among the one or more functions related to cell reselection; and assigning a cell reselection priority for the UE based on the priority; A method comprising:

2. assigning a cell reselection priority for the UE, 2. The method of claim 1, comprising indicating to the UE at least one of the cell reselection priority and the priority order among the one or more functions related to cell reselection.

3. assigning a cell reselection priority for the UE, For each of the one or more functions, determining a single network slice selection assistance information (S-NSSAI) of a slice-specific cell reselection mechanism and a corresponding network slice access stratum group (NSAG); indicating to the UE a cell reselection priority corresponding to the determined priority among the one or more functions related to cell reselection; The method of claim 1 , comprising:

4. 4. The method of claim 3, wherein the cell reselection priority is indicated in the form of at least one of an NSAG priority and a slice-specific cell reselection priority that is mapped to a corresponding NSAG.

5. 5. The method of claim 3, further comprising: transmitting, to the UE, authorized network slice selection assistance information, authorized NSSAI, including at least the one or more S-NSSAIs associated with the one or more capabilities.

6. 5. The method of claim 3, further comprising: transmitting, to the UE, configured network slice selection assistance information, configured NSSAI, including at least the one or more S-NSSAIs associated with the one or more capabilities.

7. The method of any one of claims 1 to 6, wherein the list of one or more features is determined based on a list of one or more features of interest received from the UE.

8. The method of any one of claims 1 to 7, wherein the one or more functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and / or sidelink communication.

9. The method according to any one of claims 1 to 8, wherein the one or more functions related to cell reselection are functions having a corresponding cell reselection mechanism.

10. assigning a cell reselection priority for the UE, The method according to any one of claims 1 to 9, comprising signaling to the UE the cell reselection priorities according to the priority order by system information broadcast or dedicated signaling.

11. 1. A network element of a wireless communications network, the network element being communicatively coupled to a user equipment, UE, the network element comprising: a processor; and a memory having instructions that, when executed by the processor, cause the network element to: identifying a list of one or more features provided by the wireless communications network, each feature on the list associated with at least one of a service capability of the UE and a service requirement of the UE; determining a priority among the one or more functions related to cell reselection; and assigning a cell reselection priority for the UE based on the priority; A network element that causes

12. 12. The network element of claim 11, wherein the network element is caused to assign a cell reselection priority to the UE by being caused to indicate to the UE at least one of the cell reselection priority and the priority among the one or more functions related to cell reselection.

13. The network element For each of the one or more functions, determining a single network slice selection assistance information (S-NSSAI) of a slice-specific cell reselection mechanism and a corresponding network slice access stratum group (NSAG); indicating to the UE a cell reselection priority corresponding to the determined priority among the one or more functions related to cell reselection; 12. The network element of claim 11, wherein the network element is caused to assign a cell reselection priority for the UE by being caused to:

14. 14. The method of claim 13, wherein the cell reselection priority is indicated in the form of at least one of an NSAG priority and a slice-specific cell reselection priority that is mapped to a corresponding NSAG.

15. The network element according to claim 13 or 14, further configured to send to the UE authorized network slice selection assistance information, authorized NSSAI, including at least the one or more S-NSSAIs associated with the one or more functions.

16. The network element according to claim 13 or 14, further being caused to send to the UE configured network slice selection assistance information, configured NSSAI, including at least the one or more S-NSSAIs associated with the one or more capabilities.

17. A network element according to any one of claims 11 to 16, wherein the list of one or more capabilities is based on a list of one or more capabilities of interest received from the UE.

18. 18. The network element of claim 11, wherein the one or more functions include at least one of slice-specific cell reselection, multicast broadcast services, high speed data network specific, and sidelink communications.

19. A network element according to any one of claims 11 to 18, wherein said one or more functions related to cell reselection are one or more functions having a corresponding cell reselection mechanism.

20. 20. The network element of claim 11, wherein the network element is caused to assign cell reselection priorities for the UE by being caused to signal the cell reselection priorities to the UE according to the priority order by system information broadcast or dedicated signaling.

21. A user equipment, UE, communicatively coupled to a network element of a wireless communications network, the user equipment, UE, comprising: a processor; and a memory having instructions that, when executed by the processor, cause the UE to: receiving, from the network element, a cell reselection priority corresponding to a determined priority among one or more functions related to cell reselection, the cell reselection priority including at least one of a network slice access stratum group, an NSAG, a priority, and a slice-specific cell reselection priority mapped to each corresponding NSAG, each of the one or more functions being provided by the wireless communications network and associated with at least one of a service capability of the UE and a service request of the UE; applying a slice-specific cell reselection mechanism based on the NSAG priority or based on the slice-specific cell reselection priority; The UE performs the above.

22. 22. The UE of claim 21, further configured to receive, from the network element, authorized network slice selection assistance information, authorized-NSSAI, including at least one single network slice selection assistance information, S-NSSAI, associated with the one or more capabilities for cell reselection.

23. 22. The UE of claim 21, further configured to receive, from the network element, configured network slice selection assistance information, configured NSSAI, comprising at least one single network slice selection assistance information, S-NSSAI, associated with the one or more capabilities for cell reselection.

24. The UE of any one of claims 21 to 23, wherein the one or more functions include at least one of slice-specific cell reselection, multicast broadcast services, high-speed data network specific, and sidelink communication.

25. 22. The UE of claim 21, wherein the UE is caused to receive the cell reselection priorities by being caused to receive the cell reselection priorities by system information broadcast or dedicated signaling.

26. 1. A method for slice-based cell reselection performed by a user device, comprising: Receiving at least one network slice access stratum group, an NSAG, and priority information of the at least one NSAG; deriving a reselection priority for the slice-based cell reselection according to a predetermined scheme based on the at least one NSAG and priority information of the at least one NSAG; Including, The method of claim 1, wherein the user device does not modify the reselection priority even if other factors for cell reselection other than slice-based cell reselection trigger the cell reselection.

27. 27. The method of claim 26, wherein the priority information for the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities for a corresponding one or more frequencies mapped to the at least one NSAG.

28. 1. A user device supporting slice-based cell reselection, comprising: a processor; and a memory having instructions that, when executed by the processor, cause the user device to: Receiving at least one network slice access stratum group, an NSAG, and priority information of the at least one NSAG; deriving a reselection priority for the slice-based cell reselection according to a predetermined scheme based on the at least one NSAG and priority information of the at least one NSAG; Let them do this, The processor and the memory do not cause the user device to modify the reselection priority even if other factors for cell reselection other than slice-based cell reselection trigger the cell reselection.

29. 30. The user device of claim 28, wherein the priority information for the at least one NSAG includes at least one of a priority for each NSAG and one or more priorities for one or more corresponding frequencies mapped to the at least one NSAG.

30. A computer-readable storage medium storing instructions which, when executed by at least one processor, cause a computer to execute the method of any one of claims 1 to 10 or to implement the method of any one of claims 26 to 27.

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