Patent Description:
Under the next generation (e.g., <NUM>th generation new radio) network architecture, the Evolved Universal Terrestrial Radio Access (E-UTRA) and New Radio tight interworking (also referred to as "LTE-NR tight interworking") is a key feature for NR Non-Standalone (NSA) deployments. The LTE-NR tight interworking can also be regarded as a transition from legacy LTE deployments to NR Standalone (SA) deployments. The <NUM> NR network architecture includes several options, among which Option <NUM>/3A/3X, Option <NUM>/4A, and Option <NUM>/7A are variants of the LTE-NR tight interworking.

<FIG> illustrate Options <NUM> and 3A, respectively, where Options <NUM> and 3A are examples of E-UTRA-NR Dual Connectivity (EN-DC). Options <NUM> and 3A each include an LTE eNB as an anchor node coupled to an Evolved Packet Core (EPC), and an NR next generation Node B (gNB) coupled to the LTE eNB. In <FIG>, the LTE eNB connects to the EPC through an S1-C interface for control plane transmissions and an S1-U interface for user plane transmissions. The NR gNB control plane connects to the EPC through the LTE eNB, where an Xx/Xn interface couples the LTE eNB and the NR gNB. The NR gNB user plane also connects to the EPC through the LTE eNB. In <FIG>, the anchor LTE eNB connects to the EPC through an S1-C interface for control plane transmissions and an S1-U interface for user plane transmissions. The NR gNB control plane connects to the EPC through the LTE eNB, where an Xx/Xn interface couples the LTE eNB and the NR gNB. Different from <FIG>, in <FIG>, the NR gNB user plane may connect directly to the EPC through an S1-U interface.

<FIG> illustrate Options <NUM> and 4A, respectively, where Options <NUM> and 4A are examples of NR E-UTRA Dual Connectivity (NE-DC). Options <NUM> and 4A each include an NR gNB as an anchor node coupled to a Next Generation Core (NGC), which is also known as a <NUM>-Core Network (<NUM>-CN) or a <NUM> Core Network (5GC). Options <NUM> and 4A also each include an eLTE eNB coupled to the NR gNB. It is noted that eLTE is a radio access technology with one or more nextgeneration evolved nodeBs (ng-eNBs) connected to a 5GC, where the ng-eNBs may also be referred to as eLTE eNBs. In this disclosure, we can use eLTE, ng-eNB, and LTE connected to 5GC, interchangeably. In <FIG>, the NR gNB connects to the NGC through an NG-C interface for control plane transmissions and an NG-U interface for user plane transmissions. The eLTE eNB control plane connects to the NGC through the NR gNB, where an Xx/Xn interface couples the eLTE eNB and the NR gNB. The eLTE eNB user plane also connects to the NGC through the NR gNB. In <FIG>, the NR gNB connects to the NGC through an NG-C interface for control plane transmissions and an NG-U interface for user plane transmissions. The eLTE eNB control plane connects to the NGC through the NR gNB, where an Xx/Xn interface couples the eLTE eNB and the NR gNB. Different from <FIG>, in <FIG>, the eLTE eNB user plane may connect directly to the NGC through an NG-U interface.

<FIG> illustrate Options <NUM> and 7A, respectively, where Options <NUM> and 7A are examples of Next Generation E-UTRA-NR Dual Connectivity (NG EN-DC). Options <NUM> and 7A each include an eLTE eNB as an anchor node coupled to an NGC (e.g., <NUM>-CN or 5GC). Options <NUM> and 7A also each include an NR gNB coupled to the eLTE eNB. In <FIG>, the eLTE eNB connects to the NGC through an NG-C interface for control plane transmissions and an NG-U interface for user plane transmissions. The NR gNB control plane connects to the NGC through the eLTE eNB, where an Xx/Xn interface couples the NR gNB and the eLTE eNB. The NR gNB user plane also connects to the NGC through the eLTE eNB. In <FIG>, the eLTE eNB connects to the NGC through an NG-C interface for control plane transmissions and an NG-U interface for user plane transmissions. The NR gNB control plane connects to the NGC through the eLTE eNB, where an Xx/Xn interface couples the NR gNB and the eLTE eNB. Different from <FIG>, in <FIG>, the NR gNB user plane may connect directly to the NGC through an NG-U interface.

It should be noted that the term, "eLTE", is only used in the study phase of TR <NUM>, for example. This term may not be used in normative specifications. However, in the present application, the term "eLTE" in the present application may include, but is not limited to, the definition in the study phase of TR <NUM> and any communication standard with equivalent functionalities. An eLTE eNB is an evolution of eNB that supports connectivity to both an EPC and an NGC, or to an NGC only. An eLTE eNB can also be referred to a next generation evolved Node B (ng-eNB), which is an LTE eNB connected to a 5GC. In the present application, eLTE, ng-eNB, and LTE connected to 5GC may be used interchangeably. In addition, an LTE eNB may not support <NUM> features such as network slice in Radio Access Network (RAN), while an eLTE eNB can support <NUM> features with higher layer network slice support. For example, an LTE eNB may directly connect to an EPC, but not to an NGC. An eLTE eNB may directly connect to both an EPC and an NGC, or to an NGC only. An NR gNB may support <NUM> features such as network slice in RAN with all layers (e.g., including SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer) layers), and etc. It is also noted that the terms, NGC, 5GC and <NUM>-CN may be used interchangeably throughout the present application.

In the current NR study phase, LTE-NR tight interworking is agreed to have dual connectivity (DC), which may similar to Rel-<NUM> dual connectivity. The LTE eNBs, eLTE eNBs, and NR gNBs can each be a master node and/or a secondary node. Among other differences from the Rel-<NUM> DC, in the <NUM> NR architecture, a secondary node may have its own Radio Resource Control (RRC) entity.

As presented in each of <FIG>, a user equipment (UE) is coupled to a master node and a secondary node, where the master node and the secondary node each have their own RRC entity. The UE has a single RRC state machine that follows the RRC state of the master node. Each node generates RRC Packet Data Units (PDUs) and inter-node PDUs using ASN. In an embedded approach, the RRC PDUs and inter-node PDUs generated by the secondary node can be embedded with the RRC PDUs generated by the master node, and be transported through the master node to the UE. The embedded approach is used for the first configuration, for the secondary node RRC reconfiguration requiring the master node RRC reconfiguration, and for the master node RRC reconfiguration requiring the secondary node RRC reconfiguration. In a direct approach, once the UE is configured to establish a Signaling Radio Bearer (SRB) in a Secondary Cell Group (SCG), the RRC PDUs generated by the secondary node can be sent directly between the secondary node and the UE. The direct approach (e.g., SCG SRB) is used for the secondary node RRC reconfiguration not requiring any coordination with the master node, and for mobility measurement report within the secondary node. In an SCG split SRB approach, the RRC PDUs and inter-node PDUs generated by the secondary node are transmitted through the lower layers (e.g., RLC, MAC, and/or PHY layers) of the master node.

In addition to LTE-NR tight interworking, network slice is another important feature of the <NUM> NR network architecture. With network slice, an operator can create a network customized to a specific market scenario or for a specific service, which demands specific requirements. To support network slice, Network Slice Selection Assistance Information (NSSAI) may be applied, which includes one or more Single Network Slice Selection Assistance Information (S-NSSAI). Each network slice may be uniquely identified by an S-NSSAI, which also represents the slice ID used for signaling between a Radio Access Network (RAN) and a Core Network (CN).

In a <NUM>-CN, a Network Slice Selection Function (NSSF) can select an appropriate network slice ID for a UE to satisfy its service requirement. A Network Slice Template (NST) may include a logical network function and resource requirements necessary to provide the required/requested service. A Network Slice Instance (NSI) is an instance created from an NST. Thus, network slice is also known as a concept for describing a system behavior implemented through NSIs. Each NSI is associated with a network slice type ID (NS-ID), used to identify the type of slice.

Currently, an LTE eNB connecting to an EPC may not support network slice. That is, an LTE eNB does not have service differentiation, and cannot read the network slice specific messages. Furthermore, an NR gNB and an eLTE eNB each have their own network slice capabilities, but the NR gNB and the eLTE eNB may not support all the services.

Although LTE-NR tight interworking and network slice are important features of the <NUM> NR architecture, not all Radio Access Technologies (RATs) in the LTE-NR tight interworking deployments support network slice.

Thus, it is desirable that LTE-NR tight interworking can support the network slice, especially when an NR gNB serves as the anchor node and connected to a <NUM>-CN. It is also desirable that the NR gNB/cell can support the RAN part of slicing (e.g., RAN part of network slice, via multiple numerologies/TTI (Transmission Time Interval) lengths, RAN part configuration of network slice), and the eLTE eNB/cell can support the higher layer network slicing. In addition, when a UE is configured with LTE-NR interworking, which may include many deployment scenarios, it is important to make sure that the UE connects to a suitable/appropriate RAT, which can support the UE's desired network slice(s)/service(s). For example, the UE may be suggested to camp to an appropriate RAT that can support its service during cell selection/reselection. For example, when the UE is in RRC_CONNECTED state and needs new network slice(s)/service(s), the UE may be suggested to connect to an appropriate RAT, which can further support the UE's new network slice(s)/service(s) requirement(s).

<NPL> relates to NAS-AS split procedures.

<NPL> relates to changes to 3GPP TR24.

<NPL> relates to the impact of slice availability on IDLE mode.

<NPL> relates to NW slicing in multiple connectivity contexts.

The present disclosure is directed to methods, devices, and systems for service-driven mobility management.

In a first aspect of the present application, a method for a user equipment (UE), the method comprising: identifying, by a non-access stratum (NAS) of the UE while the UE is in a Radio Resource Control (RRC) inactive (RRC_Inactive), or RRC idle (RRC_Idle) state, a selected Public Land Mobile Network (PLMN) and one or more equivalent PLMNs; identifying, by the NAS of the UE, a required network slice/service of the UE based on Single Network Slice Selection Assistance Information (S-NSSAI), wherein the S-NSSAI uniquely identifies the required network slice/service; measuring signals, by an access stratum, AS, of the UE while the UE is in the RRC_inactive or RRC_Idle state, from one or more radio access technologies (RATs) and frequency bands on which the required network slice/service identified by the S-NSSAI is supported, wherein the NAS of the UE is preconfigured with information of the one or more RATs and frequency bands associated with one or more network slices/services identified by the S-NSSAI; and selecting, by the NAS, a cell that supports the required network slice/service of the UE based on the measured signals.

In an implementation of the first aspect, the S-NAASI is in the form of at least one of a Slice ID, a Network Indication, and a Slice Bitmap.

In another implementation of the first aspect, the method further comprising: forwarding, by the NAS of the UE, the information of the one or more RATs and frequency bands associated with one or more network slices/services to the AS of the UE.

In another implementation of the first aspect, the method further comprising: measuring, by the AS of the UE, signals on frequency bands supported by all RATs; and receiving slice information broadcast by cells on the frequency bands supported by all the RATs.

In another implementation of the first aspect, the method further comprising: forwarding the slice information by the AS of the UE to the NAS of the UE, wherein the NAS of the UE decides which of the RATs and frequency bands are appropriate for the required network slice/service.

In another implementation of the first aspect, the slice information comprises whether the cells support the one or more network slices/services, and what types of network slices/services are supported by the cells.

In another implementation of the first aspect, the method further comprising: identifying, by the NAS of the UE or the AS of the UE while the UE is in the RRC_Inactive or RRC_Idle state, a network slice support by the cell based on the slice information broadcast by the cell.

In another implementation of the first aspect, the method further comprising: selecting another cell based on a list of barred cells, wherein the UE is preconfigured with the list of barred cells that do not support the required network slice/service.

In another implementation of the first aspect, the one or more RATs and frequency bands are associated with the identified selected PLMN or one or more equivalent PLMNs.

In another implementation of the first aspect, the method further comprising: performing an RRC connection establishment procedure to the selected cell with a corresponding RAT and on a corresponding frequency band.

In a second aspect of the present application, a User Equipment (UE) is disclosed, the UE comprising: a non-transitory computer-readable medium storing computer-executable instructions; at least one processor coupled to the non-transitory computer-readable medium, and configured to execute the computer-executable instructions to: identify, by a non-access stratum (NAS) of the UE while the UE is in a Radio Resource Control, RRC, inactive (RRC_Inactive), or RRC idle (RRC_Idle) state, a selected Public Land Mobile Network (PLMN) and one or more equivalent PLMNs; identify, by the NAS of the UE, a required network slice/service of the UE based on Single Network Slice Selection Assistance Information (S-NSSAI), wherein the S-NSSAI uniquely identifies the required network slice/service; measure signals, by an access stratum (AS) of the UE while the UE is in the RRC_Inactive or RRC_Idle state, from one or more radio access technologies (RATs) and frequency bands on which the required network slice/service identified by the S-NSSAI is supported, wherein the NAS of the UE is preconfigured with information of the one or more RATs and frequency bands associated with one or more network slices/services identified by the S-NSSAI; and select, by the NAS of the UE, a cell that supports the required network slice/service of the UE based on the measured signals; wherein the S-NSSAI is in the form of at least one of a Slice ID, a Network Slice Indication, or a Slice Bitmap.

In an implementation of the second aspect, measure, by the AS of the UE, signals on frequency bands supported by all RATs; receive slice information broadcast by cells on the measured frequency bands supported by all the RATs; and forward the slice information by the AS of the UE to the NAS of the UE, wherein the NAS of the UE decides which of the RATs and frequency bands are appropriate for the required network slice/service; wherein the slice information comprises whether the cells support the one or more network slices/services, and what types of network slices/services are supported by the cells.

In another implementation of the second aspect, the at least one processor is further configured to execute the computer-executable instructions to: select another cell based on a list of barred cells, wherein the UE is preconfigured with the list of barred cells that do not support the required network slice/service.

In another implementation of the second aspect, the at least one processor is further configured to execute the computer-executable instructions to: identify, by the NAS of the UE, a selected Public Land Mobile Network (PLMN) and one or more equivalent PLMNs; wherein the one or more RATs and frequency bands are associated with the identified selected PLMN or one or more equivalent PLMNs.

In another implementation of the second aspect, the at least one processor is further configured to execute the computer-executable instructions to: perform an RRC connection establishment procedure to the selected cell with a corresponding RAT and on a corresponding frequency band.

In the following detailed description, embodiments of the invention are described with reference to <FIG> and the associated paragraphs(s). Other figures and passages referring to aspects or exemplary implementation of the present disclosure, which may include some but not all features of the claims, are presented for illustrative purposes allowing a better understanding of the invention.

The following description contains specific information pertaining to exemplary implementations in the present disclosure. The drawings in the present disclosure and their accompanying detailed description are directed to merely exemplary implementations. However, the present disclosure is not limited to merely these exemplary implementations. Other variations and implementations of the present disclosure will occur to those skilled in the art. Unless noted otherwise, like or corresponding elements among the figures may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present disclosure are generally not to scale, and are not intended to correspond to actual relative dimensions.

In some implementations, this disclosure may include the language, for example, "at least one of [element A] or [element B]". This language may refer to one or more of the elements. For example, "at least one of A or B" may refer to "A", "B", or "A and B". In other words, "at least one of A or B" may refer to "at least one of A and at least one of B," or "at least of either A or B. " In some implementations, this disclosure may include the language, for example, "[element A], [element B], and/or [element C]. " This language may refer to either of the elements or any combination thereof. In other words, "A, B, and/or C" may refer to "A", "B", "C", "A and B", "A and C", "B and C", or "A, B, and C".

In some of the exemplary implementations, an EPC may not support network slice, unlike the NGC (e.g., <NUM>-CN and 5GC) which may support network slice. In some of the exemplary implementations, an LTE eNB may not support network slice, unlike the eLTE eNB and NR gNB which may support network slice. In some of the exemplary implementations, an eLTE eNB/cell may not support RAN part of slicing (e.g., RAN part of network slice, via multiple numerologies/TTI lengths, RAN part configuration of network slice), but may support network slice from RRC, SDAP, and PDCP layers. In some of the exemplary implementations, an NR gNB/cell may support RAN part of slicing from an RRC layer and an SDAP layer to a PHY layer (e.g., via different numerologies/TTI lengths). When a CN is a <NUM>-CN, the CN may support the storage and selection of network slice. For example, a <NUM>-CN may store the network slice/service information (e.g., NS-IDs, S-NSSAIs, and/or slice IDs) of each registered NR gNB/cell and eLTE eNB/cell. The <NUM>-CN may also select the proper NR gNB/cell and eLTE eNB/cell for the UE's network slice/service request. It is noted that the capabilities of network slice/service supported by each RAT/cell may be different. In some of the exemplary implementations, an eLTE eNB and/or NR gNB may not have the capability to support all network slices/services defined by the core network. In some of the exemplary implementations, the capabilities of these network entities are summarized in Table <NUM>. It is noted that the network slices/services supported by RATs may be a subset of the network slices/services supported by the CN.

In some of the exemplary implementations, NR gNBs and eLTE eNBs may generate/read/transmit/receive/forward network slice/service related RRC messages. The NR gNBs and eLTE eNBs may support SDAP and PDCP to connect to a 5GC. The NR gNBs may further provide RAN part of slicing (e.g., RAN part of network slice, via multiple numerologies/TTI lengths, RAN part configuration of network slice) to support different network slices/services. Based on the <NUM> NR architecture and the capability of network slice of each network entity, four cases of interest are shown in <FIG>, where control plane connections are shown. In <FIG>, Case 500A refers to LTE and NR tight interworking and LTE as the anchor connecting to EPC. In <FIG>, Case 500B refers to eLTE and NR tight interworking and eLTE as the anchor connecting to the <NUM>-CN (e.g., Next Generation E-UTRAN NR Dual Connectivity, NGEN-DC). In <FIG>, Case 500C refers to eLTE and NR tight interworking (e.g., NR E-UTRAN Dual Connectivity, NE-DC) and NR as the anchor connecting to the <NUM>-CN. In <FIG>, Case 500D refers to eLTE and NR tight interworking and eLTE as the anchor connecting to the EPC.

In the implementations illustrated in Case 500B of <FIG>, Case 500C of <FIG>, and Case 500D of <FIG>, the master node and secondary node may be either an eLTE eNB/cell or an NR gNB/cell, and the core network may be either an EPC or a <NUM>-CN. In other words, the eLTE eNB/cell can be either a master node or a secondary node. When the eLTE eNB/cell is the master node, the secondary node is NR gNB/cell, and the core network is EPC in Case 500D or 5GC in Case 500B. When the eLTE eNB/cell is the secondary node, the master node is an NR gNB/cell, and the core network is 5GC in Case 500C. The objective is to ensure that the UE configured with eLTE-NR tight interworking, such as in Cases 500B, 500C, and 500D, can connect to the appropriate RAT, which supports the UE's required/requested or updated network slices and/or services.

There are several cases where a UE may need assistance to connect to a suitable node that supports the UE's specific network slice(s) and/or service(s). For example, when a UE performs initial access, the UE may connect to a master node, which cannot support its network slice and/or service requirements. In another case, even after the UE performs initial access and connects to a suitable master node, which supports its initial network slice, the master node may become unsuitable when the UE changes/updates the network slice, for example, in RRC_CONNECTED state. In another case, a UE with network slice capability turns to the secondary node for the network slice/service. Exemplary implementations of the present application describe various methods/mechanisms for ensuring a UE connect to a suitable node, which supports the UE's specific network slice(s) and/or service(s).

It is noted that the cell IDs and base station IDs in the present application may refer to NR gNB ID, NR cell ID, (e)LTE eNB ID, (e)LTE cell ID, global unique base station ID (e.g., PLMN ID plus eNB ID for LTE), unique base station ID in a PLMN (e.g., eNB ID for LTE), NR/E-UTRAN Cell Identity (e.g., eNB ID plus cell ID for LTE), global NR/E-UTRAN Cell Identity (e.g., PLMN ID plus eNB ID plus cell ID for LTE, Tracking Area Code plus PLMN ID plus cell ID for NR), PCI (Physical Cell Identifier) which is derived from PSS (Primary Synchronization Signals) and/or SSS (Secondary Synchronization Signals).

A UE may reveal its network slice capability and/or requirement to an eLTE eNB/cell through an RRC message. The eLTE eNB/cell may be a master node/cell in a Master Cell Group (MCG) as shown in <FIG>, or a secondary node/cell in a Secondary Cell Group (SCG) as shown in <FIG>.

<FIG> is a diagram illustrating an MCG SRB and an MCG split SRB with an eLTE eNB/cell as a master node, according to an exemplary implementation of the present disclosure. As shown in <FIG>, when eLTE eNB/cell <NUM> is a master node, the control signaling revealing a UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, may be provided through one or more MCG Signaling Radio Bearers (SRBs) and/or one or more MCG split SRBs. As shown in <FIG>, eLTE eNB/cell <NUM> may be a master node in an MCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. NR gNB/cell <NUM> may be a secondary node in an SCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The control signaling revealing the UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, may be provided through an MCG SRB via RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM>. Instead of, or in addition to, the control signaling being provided through the MCG SRB, the control signaling revealing the UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, may be provided through an MCG split SRB, via RRC layer <NUM> and PDCP layer <NUM> of eLTE eNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM> (e.g., secondary node in an SCG).

<FIG> is a diagram illustrating an SCG SRB and an SCG split SRB with an eLTE eNB/cell as a secondary node, according to an exemplary implementation of the present disclosure. It is noted that SCG SRB may also be regarded as SRB3. As shown in <FIG>, when eLTE eNB/cell <NUM> is a secondary node, the control signaling revealing the UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, may be provided through one or more SCG SRBs and/or one or more SCG split SRBs. As shown in <FIG>, NR gNB/cell <NUM> may be a master node in an MCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. eLTE eNB/cell <NUM> is a secondary node in an SCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The control signaling revealing the UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, can be provided through an SCG SRB via RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM>. Instead of, or in addition to, the control signaling being provided through the SCG SRB, the control signaling revealing the UE's network slice capability, between the UE and eLTE eNB/cell <NUM>, may be provided through an SCG split SRB, via RRC layer <NUM> and PDCP layer <NUM> of eLTE eNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM> (e.g., the master node in an MCG).

As illustrated in <FIG>, <FIG>, <FIG> and <FIG>, a UE reveals its network slice capability and/or service requirement for network slice in an RRC message (e.g., RRC Connection Request or RRC Connection Setup Complete or RRC Connection Establishment or RRC System Information Request). The RRC message may include a UE ID to reveal the UE identity. The RRC message may include slice IDs and/or network slice type ID (NS-ID) to directly identify the type of network slice and/or required/requested service the UE needs. In another exemplary implementation, a slice bitmap may be used to directly identify the type of network slice and/or required/requested service in the RRC message. For example, the slice bitmap may include preconfigured N bits (e.g., N supported network slices/services), with a bit "<NUM>" meaning the corresponding network slice/service is supported, and a bit "<NUM>" meaning the corresponding network slice/service is not supported.

It should be noted that, in the present application, slice IDs in all figures are used for illustration purpose only. That is, the slice IDs can be replaced with slice bitmaps to identify the indicated network slices/services. The cause value in an RRC message may be 'network slice' corresponding to a NAS (Non-Access Stratum) procedure. Moreover, the RRC message may carry the network slice indication (NS Indication), to indicate the network slice requirement instead of explicitly revealing the slice service type.

In exemplary implementations of the present application, the eLTE eNB/cell, after receiving the RRC message, may take the following actions: Case 1A - reject through an RRC message without providing any further information; Case 1B - reject through an RRC message and provide assisting information in the RRC message; Case 1C - accept through an RRC message. It should be noted that the RRC message exchange between the UE and the eLTE eNB is not limited to the eLTE eNB as a master node or a secondary node under dual-connectivity operation. For example, the RRC message exchange between the UE and the eLTE eNB may also be applicable when the eLTE eNB is a standalone node.

<FIG> is a diagram illustrating an eLTE eNB/cell rejecting network slice without providing further information, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> sends a network slice/service request through an RRC message, such as an RRC Message for Request (e.g., including UE ID, Slice IDs, NS Indication, and/or Slice Bitmap) to eLTE eNB/cell <NUM>. In action <NUM>, eLTE eNB/cell <NUM> responds with an RRC Message for Rejection (e.g., Cause: no network slice support). That is, eLTE eNB/cell <NUM> reads the RRC message from UE <NUM>, and directly responds with an RRC dedicated signaling to reject the network slice support without any further information. In one example, eLTE eNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because the core network such as an EPC cannot recognize/support the establishment cause of network slice (e.g., Case 500D in <FIG>). In another example, eLTE eNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because the EPC does not support network slice function even though eLTE eNB/cell <NUM> recognizes the slice IDs and/or NS Indication and/or slice bitmap. In yet another example, eLTE eNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because eLTE eNB/cell <NUM> itself cannot support the required/requested network slice/service, and/or eLTE eNB/cell <NUM> is configured not to perform the network slice inquiry to other nodes/cells (e.g., eLTE eNBs/cells and NR gNBs/cells in MCG and SCG), and/or eLTE eNB/cell <NUM> attempts to find a suitable eLTE eNB/cell and NR gNB/cell but ends up unsuccessful. It may be also because that UE <NUM> is not configured with eLTE-NR interworking so that eLTE eNB/cell <NUM> cannot forward the RRC message to other nodes/cells in MCG or SCG (e.g., eLTE eNBs/cells and NR gNBs/cells) for network slice inquiry. In general, failure cases occur so that eLTE eNB/cell <NUM> rejects UE <NUM>'s request. Once eLTE eNB/cell <NUM> rejects the network slice support via RRC signaling, the RRC message for rejection (e.g., RRC Message for Rejection) can involve a cause (e.g., no network slice support as shown in <FIG>) or any of the above mentioned reasons.

In one exemplary implementation, the RRC message for rejection may include a prohibit timer. The prohibit timer may be activated either when eLTE eNB/cell <NUM> sends the RRC message for rejection or when UE <NUM> receives the RRC message for rejection. Once the prohibit timer is activated, UE <NUM> is not allowed to camp to eLTE eNB/cell <NUM> until the prohibit timer expires. In another exemplary implementation, once the prohibit timer is activated, UE <NUM> cannot request the same network slice/service from any base station until the prohibit timer expires. The prohibit timer stops either when the prohibit timer expires or when eLTE eNB/cell <NUM> updates its network slice support (e.g., UE <NUM> may constantly monitor the network slice support while the prohibit timer is running). Upon receiving the RRC dedicated signaling from eLTE eNB/cell <NUM> for network slice support rejection, UE <NUM> may perform the MCG-related procedures (e.g., handover to another master node that supports the required/requested network slice/service, or the inter-MN (master node) handover without the change of the secondary node), or SCG-related procedures (e.g., secondary node change/addition/modification, or beam change/addition/modification, so that the new/target master node or secondary node or beam supports the required/requested network slice/service). In the present application, UE <NUM> may have multi-connectivity with a number of base stations to support the network slice/service. In the present application, it is noted that UE <NUM> may record the cell ID that can't support respective network slicing and have corresponding prioritization (e.g. low priority) for cell (re-)selection, handover and the selection of master nodes and secondary nodes.

<FIG> is a diagram illustrating an eLTE eNB/cell rejecting network slice and providing further information, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> sends a network slice/service request through an RRC message, such as an RRC Message for Request (e.g., including UE ID, Slice IDs/NS Indication/Slice Bitmap) to eLTE eNB/cell <NUM>. In action <NUM>, although eLTE eNB/cell <NUM> rejects the required/requested network slice/service (the cause may be the same in Case 1A), eLTE eNB/cell <NUM> may provide UE <NUM> with information of other eLTE eNBs/cells and NR gNBs/cells in the RRC message to assist UE <NUM> to connect to a suitable NR gNB/cell or eLTE gNB/cell that can provide UE <NUM>'s requested network slice/service. For example, eLTE eNB/cell <NUM> is configured to send network slice inquiries to other nodes/cells or the core network.

According to implementations of the present application, there are two approaches to acquire the information of network slice/service support. The first approach is direct coordination with other eLTE eNBs/cells and NR gNBs/cells. The second approach is to send the inquiry to the core network, such as a <NUM>-CN.

In the first approach, eLTE eNB/cell <NUM> sends an Xx/Xn message including UE <NUM>'s requested network slice/service information (e.g., Slice IDs/NS Indication/Slice Bitmap) to other eLTE eNBs/cells and NR gNBs/cells. Those eLTE eNBs/cells and NR gNBs/cells, which can support UE <NUM>'s requested network slice/service, respond to eLTE eNB/cell <NUM> with acknowledgement so that eLTE eNB/cell <NUM> can provide UE <NUM> with a list of IDs of eLTE eNBs/cells and NR gNBs/cells/beams which can satisfy UE <NUM>'s network slice/service request.

In the second approach, the core network (e.g., <NUM>-CN) may already have stored what types of network slice/service are supported by which eLTE eNBs/cells and NR gNBs/cells. Therefore, eLTE eNB/cell <NUM> may send NG-C signaling to the core network including UE <NUM>'s requested network slice/service. The core network may retrieve the information of suitable eLTE eNBs/cells and NR gNBs/cells, and provide a list of suitable eLTE eNB/cell and NR gNB/cell IDs to eLTE eNB/cell <NUM> through NG-C signaling. eLTE eNB/cell <NUM> may either first filter the list (e.g., remove the blocked cells) before transmitting it to UE <NUM>, or directly transmit the list to UE <NUM> without any modification.

After eLTE eNB/cell <NUM> acquires the information regarding which eLTE eNBs/cells and NR gNBs/cells support UE <NUM>'s network slice/service request, eLTE eNB/cell <NUM> may respond to UE <NUM> with an RRC message (e.g., RRC Connection Reject or RRC Connection Reconfiguration), where the RRC message includes information such as target NR gNB/cell/beam or LTE eNB/cell or eLTE eNB/cell ID, and/or a list of suitable NR gNB/cell/beam IDs and/or LTE eNB/cell IDs and/or eLTE eNB/cell IDs, and/or specific preamble of the target NR gNB/cell or LTE eNB/cell or eLTE eNB/cell, and/or target NR SS (Synchronization Signal) block/burst/burst set configuration, and/or a list of suitable NR SS block/burst/burst set configurations, as illustrated in <FIG>. The SS block/burst/burst set may include synchronization signals and/or reference signals for UE <NUM> to do measurements. Thus, UE <NUM> may perform measurements to the target NR gNB/cell/beam or LTE eNB/cell or eLTE eNB/cell or a list of NR gNBs/cells/beams or LTE eNBs/cells or eLTE eNBs/cells. Moreover, with the information of preamble, the target node/cell may regard UE <NUM> as a special UE, and provide UE <NUM> with privilege during the random access procedure. Providing the beam information and the SS block/burst/burst set configurations to UE <NUM> may be beneficial, when different beams can support different network slices/services (different numerology/TTI length configurations) in NR.

In other implementations, eLTE eNB/cell <NUM> may directly select a target NR gNB/cell/beam or a target LTE eNB/cell or a target eLTE eNB/cell for UE <NUM>, and send an RRC message (e.g., RRC Connection Reject or RRC Connection Reconfiguration) including the cell ID, and/or preamble, and/or beam ID (if supported), and/or SS block/burst/burst set configuration (if supported) of target NR gNB/cell or a target LTE eNB/cell or a target eLTE eNB/cell to UE <NUM>. UE <NUM> may perform the handover to another master node which supports the required/requested network slice/service, or the inter-MN handover without the change of the secondary node, or secondary node change/addition/modification so that the new/target secondary node supports the required/requested network slice/service. In the present implementation, UE <NUM> may have multi-connectivity with a number of base stations to support the network slice/service. It is noted that the NR gNBs/cells and eLTE eNBs/cells chosen by eLTE eNB/cell <NUM> may at least provide the network slice function, and optionally provide UE <NUM>'s specific requested network slice/service.

In other implementations, the RRC message for rejection may include a prohibit timer. The prohibit timer may be activated either when eLTE eNB/cell <NUM> sends the RRC message for rejection or when UE <NUM> receives this RRC message for rejection. Once the prohibit timer is activated, UE <NUM> may not be allowed to camp to eLTE eNB/cell <NUM> until the prohibit timer expires. In another implementation, once the prohibit timer is activated, UE <NUM> cannot request the same network slice/service from any base station until the prohibit timer expires. The prohibit timer stops either when the timer expires or when eLTE eNB/cell <NUM> updates its network slice support (e.g., UE <NUM> may constantly monitor the network slice support while the prohibit timer is running).

An eLTE eNB/cell reads the RRC message including a UE's network slice/service request, and decides to provide such network slice/service on its own.

<FIG> is a diagram illustrating an MCG bearer and an MCG split bearer (e.g., a split bearer) with an eLTE eNB/cell as a master node, according to an exemplary implementation of the present disclosure. When eLTE eNB/cell <NUM> is a master node, the network slice may be provided through an MCG split bearer and/or an MCG bearer, as shown in <FIG>. For example, eLTE eNB/cell <NUM> may reply to the UE with an RRC message (e.g., RRC Connection Setup or RRC Reconfiguration) through an MCG SRB or an MCG split SRB, indicating the related parameters to build the MCG split bearer.

As shown in <FIG>, eLTE eNB/cell <NUM> may be a master node in an MCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. NR gNB/cell <NUM> may be a secondary node in the SCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The network slice may be provided through an MCG bearer via SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM>. Instead of, or in addition to, the network slice being provided through the MCG bearer, the network slice may be provided through an MCG split bearer via SDAP layer <NUM>, PDCP layer <NUM> of eLTE eNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM> (e.g., a secondary node). In some implementations, NR gNB/cell <NUM> is a selected NR gNB/cell that supports the RAN part of slicing. In some implementations, the selected NR gNB/cell may utilize an existing secondary cell in an SCG or add a new secondary cell to the SCG. Thus, SCG-related procedures may be utilized to realize the MCG split bearer.

<FIG> is a diagram illustrating an SCG bearer and an SCG split bearer (e.g., a split bearer) with an eLTE eNB/cell as a secondary node, according to an exemplary implementation of the present disclosure. When eLTE eNB/cell <NUM> is a secondary node, the network slice may be provided through an SCG split bearer and/or an SCG bearer, as shown in <FIG>. For example, eLTE eNB/cell <NUM> may reply to the UE with an RRC message (e.g., RRC Connection Setup or RRC Reconfiguration) through an SCG SRB and/or an SCG split SRB, indicating the related parameters to build the SCG split bearer.

As shown in <FIG>, eLTE eNB/cell <NUM> may be a secondary node in an SCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. NR gNB/cell <NUM> may be a secondary node in the MCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The network slice may be provided through an SCG bearer via SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM>. Instead of, or in addition to, the network slice being provided through the SCG bearer, the network slice may be provided through an SCG split bearer via SDAP layer <NUM>, PDCP layer <NUM> of eLTE eNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM> (e.g., a master node). In some implementations, NR gNB/cell <NUM> is a selected NR gNB/cell that supports the RAN part of slicing. In some implementations, the selected NR gNB/cell may utilize an existing master cell in an MCG or add a new master cell to the MCG. Thus, MCG-related procedures may be utilized to realize the SCG split bearer.

It is noted that SCG-related procedures 1214A in <FIG>, and MCG-related procedures 1214B in <FIG>, may include beam-level operations, such as beam addition (e.g., add NR beams that support the required/requested network slice), beam change (e.g., change from the serving NR beam to a new beam that support the required/requested network slice), and beam modification (e.g., modify a beam so that the beam supports the required/requested network slice).

After SCG-related procedures 1214A in <FIG>, and MCG-related procedures 1214B in <FIG>, eLTE eNB/cell <NUM> informs UE <NUM> using an RRC message (e.g., RRC Connection Setup, RRC Configuration, or RRC Reconfiguration). After SCG-related procedures 1214A in <FIG>, and MCG-related procedures 1214B in <FIG>, eLTE eNB/cell <NUM> has established connection to NR gNB/cell <NUM> for the RAN part of slicing. The control signaling exchange for the SCG-related or MCG-related procedures occurs in an Xx/Xn interface. The exchanged information may include UE ID, Slice IDs, Slice Bitmap, NS Indication, target NR gNB/cell/beam, LTE eNB/cell or eLTE eNB/cell ID, a list of suitable NR gNB/cell/beam IDs and/or LTE eNB/cell IDs and/or eLTE eNB/cell IDs, and/or specific preamble of the target NR gNB/cell or LTE eNB/cell or eLTE eNB/cell, and/or target NR SS block/burst/burst set configuration, and/or a list of suitable NR SS block/burst/burst set configurations.

After receiving the RRC message (e.g., RRC Connection Setup, RRC Configuration, or RRC Reconfiguration) from eLTE eNB/cell <NUM>, UE <NUM> sends an RRC message in action <NUM>, (e.g., an RRC Connection Setup Complete, an RRC Configuration Complete, or an RRC Connection Reconfiguration Complete) to eLTE eNB/cell <NUM> through an MCG SRB or an MCG split SRB if eLTE eNB/cell <NUM> is a master node in an MCG, or through an SCG SRB or an SCG split SRB if eLTE eNB/cell <NUM> is a secondary node in an SCG.

A UE may reveal its network slice capability and/or requirement to an NR gNB/cell through an RRC message. The NR gNB/cell may be a master node in a Master Cell Group (MCG) as shown in <FIG>, or a secondary node in a Secondary Cell Group (SCG) as shown in <FIG>.

<FIG> is a diagram illustrating an MCG SRB and an MCG split SRB with an NR gNB/cell as a master node, according to an exemplary implementation of the present disclosure. As shown in <FIG>, when NR gNB/cell <NUM> is a master node, the control signaling revealing a UE's network slice capability (e.g., an RRC message), between the UE and NR gNB/cell <NUM>, may be provided through one or more MCG SRBs and/or one or more MCG split SRBs. As shown in <FIG>, NR gNB/cell <NUM> may be a master node in an MCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. eLTE eNB/cell <NUM> may be a secondary node in an SCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The control signaling revealing the UE's network slice capability, between UE and NR gNB/cell <NUM>, may be provided through an MCG SRB via RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM>. Instead of, or in addition to, the control signaling being provided through the MCG SRB, the control signaling revealing the UE's network slice capability, between the UE and NR gNB/cell <NUM>, may be provided through an MCG split SRB, via RRC layer <NUM> and PDCP layer <NUM> of NR gNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM> (e.g., a secondary node in an SCG).

<FIG> is a diagram illustrating an SCG SRB and an SCG split SRB with an NR gNB/cell as a secondary node, according to an exemplary implementation of the present disclosure. It is noted that SCG SRB may also be regarded as SRB3. As shown in <FIG>, when NR gNB/cell <NUM> is a secondary node, the control signaling revealing a UE's network slice capability, between the UE and NR gNB/cell <NUM>, may be provided through one or more SCG SRBs and/or one or more SCG split SRBs. As shown in <FIG>, eLTE eNB/cell <NUM> may be a master node in an MCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. NR gNB/cell <NUM> may be a secondary node in an SCG, and may include RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The control signaling revealing the UE's network slice capability, between the UE and NR gNB/cell <NUM>, may be provided through an SCG SRB via RRC layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of NR gNB/cell <NUM>.

Instead of, or in addition to, the control signaling being provided through the SCG SRB, the control signaling revealing the UE's network slice capability, between the UE and NR gNB/cell <NUM>, may be provided through an SCG split SRB, via RRC layer <NUM> and PDCP layer <NUM> of NR gNB/cell <NUM>, and via RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM> of eLTE eNB/cell <NUM> (e.g., a master node in an MCG). In some implementations, the control signaling (e.g., RRC messages) between the secondary node NR gNB/cell <NUM> (e.g., a secondary node in an SCG) and the UE may be transmitted via the embedded approach described herein.

In accordance with implementations as illustrated in <FIG>, <FIG>, and <FIG> of the present disclosure, a UE may reveal its network slice capability and/or service requirement in an RRC message (e.g., an RRC Connection Request or RRC Connection Setup Complete or an RRC Connection Establishment). The RRC message may include a UE ID to reveal the UE identity. The RRC message may include slice IDs and/or network slice type ID (NS-ID) to directly identify the type of network slice and/or required/requested service. In another exemplary implementation, a slice bitmap may be used to directly identify the type of network slice and/or required/requested service in the RRC message. For example, the slice bitmap may include preconfigured N bits (e.g., N supported network slices/services), with a bit "<NUM>" meaning the corresponding network slice/service is supported, and a bit "<NUM>" meaning the corresponding network slice/service is not supported.

It should be noted that, in the present application, slice IDs in the figures are merely used for illustration purposes. That is, the slice IDs may be replaced with slice bitmaps to identify the indicated network slice(s)/service(s). The cause value in an RRC message may be "network slice" corresponding to a NAS procedure. Moreover, the RRC message may carry the network slice indication (NS Indication), to indicate the network slice requirement instead of explicitly revealing the slice service type.

The RRC entity of the NR gNB/cell may recognize whether the required/requested service or the required/requested network slice function is supported. It is noted that the RRC entity of the NR gNB/cell is preconfigured for RAN part of slicing (e.g., multiple numerologies/TTI lengths for different slices) so that the NR gNB/cell can identify whether it supports the UE's service request or not.

In exemplary implementations of the present application, the NR gNB/cell, after receiving the RRC message, may take the following actions: Case 2A - reject through an RRC message without providing any further information; Case 2B - reject through an RRC message and provide assisting information in the RRC message; Case 2C - accept through an RRC message. It should be noted that the RRC message exchange between the UE and the NR gNB is not limited to the NR gNB as a master node or a secondary node under dual-connectivity operation. For example, the RRC message exchange between the UE and the NR gNB may also be applicable when the NR gNB is a standalone node.

<FIG> is a diagram illustrating an NR gNB/cell rejecting network slice without providing further information, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> sends a network slice/service request through an RRC message, such as an RRC Connection Request or RRC Connection Setup Complete (e.g., including UE ID, Slice IDs, NS Indication, and/or Slice Bitmap) to NR gNB/cell <NUM>. In action <NUM>, NR gNB/cell <NUM> responds with an RRC Connection Reject (e.g., Cause: no network slice support). That is, NR gNB/cell <NUM> reads the RRC message from UE <NUM>, and directly responds with an RRC dedicated signaling to reject the network slice support without providing any further information. In one example, NR gNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because the NR gNB/cell and/or eLTE eNB/cell cannot support the required/requested network slice/service. In another example, NR gNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because the NR gNB/cell refuses to support the required/requested network slice/service (e.g., due to no available network resource) even though it can. In yet another example, NR gNB/cell <NUM> responds with the RRC dedicated signaling to reject the network slice support because some failure cases occur in the network. After NR gNB/cell <NUM> rejects UE <NUM>'s request via the RRC message, the RRC message for rejection can involve a cause (e.g., no network slice support as shown in <FIG>) or any of the above mentioned reasons.

In one exemplary implementation, the RRC message for rejection may include a prohibit timer. The prohibit timer may be activated either when NR gNB/cell <NUM> sends the RRC message for rejection or when UE <NUM> receives the RRC message for rejection. Once the prohibit timer is activated, UE <NUM> is not allowed to camp to NR gNB/cell <NUM> until the prohibit timer expires. In another exemplary implementation, once the prohibit timer is activated, UE <NUM> cannot request the same network slice/service from any base station until the prohibit timer expires. The prohibit timer stops either when the prohibit timer expires or when the NR gNB/cell <NUM> updates its network slice support (e.g., UE <NUM> may constantly monitor the network slice support while the prohibit timer is running). Upon receiving the RRC dedicated signaling from NR gNB/cell <NUM> for network slice support rejection, UE <NUM> may perform the MCG-related procedures (e.g., handover to another master node that supports the required/requested network slice/service, or the inter-MN (master node) handover without the change of the secondary node), or SCG-related procedures (e.g., secondary node change/addition/modification, or beam change/addition/modification, so that the new/target master node or secondary node or beam supports the required/requested network slice/service). In the present application, UE <NUM> may have multi-connectivity with a number of base stations to support the network slice/service. In the present application, it is noted that UE <NUM> may record the cell ID that cannot support respective network slicing and have corresponding prioritization (e.g. low priority) for cell (re-)selection, handover and the selection of master nodes and secondary nodes.

<FIG> is a diagram illustrating an NR gNB/cell rejecting network slice and providing further information, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> sends a network slice/service request through an RRC message, such as an RRC Message for Request (e.g., including UE ID, Slice IDs/NS Indication/Slice Bitmap) to NR gNB/cell <NUM>.

In action <NUM>, NR gNB/cell <NUM> cannot establish an RRC connection for UE <NUM>'s network slice/service requirement (the cause may be the same in Case 2A), and NR gNB/cell <NUM> replies with an RRC message (e.g., RRC Message for Rejection or RRC Connection Reject). Nevertheless, NR gNB/cell <NUM> may provide further information of other NR gNBs/cells and eLTE eNBs/cells in the RRC message to assist UE <NUM> to connect to a suitable NR gNB/cell or eLTE gNB/cell that can provide UE <NUM>'s required/requested network slice/service. NR gNB/cell <NUM> is configured to send network slice inquiries to other nodes/cells or the core network.

In the first approach, NR gNB/cell <NUM> sends the Xx/Xn message including UE <NUM>'s request network slice/service information (e.g., Slice IDs, NS Indication, or Slice Bitmap) to other eLTE eNBs/cells and NR gNBs/cells. Those eLTE eNBs/cells and NR gNBs/cells, which support UE <NUM>'s request network slice/service, respond to NR gNB/cell <NUM> with acknowledgement so that NR gNB/cell <NUM> can provide UE <NUM> with a list of IDs of eLTE eNBs/cells and NR gNBs/cells/beams which can satisfy UE <NUM>'s network slice/service request.

In the second approach, the core network (e.g., <NUM>-CN) may already have stored what types of network slice/service are supported by which eLTE eNBs/cells and NR gNBs/cells. Therefore, NR gNB/cell <NUM> may send NG-C signaling to the core network including UE <NUM>'s request network slice/service. The core network may retrieve the information of suitable eLTE eNBs/cells and NR gNBs/cells, and provide the list of suitable eLTE eNB/cell and NR gNB/cell IDs to NR gNB/cell <NUM> through NG-C signaling. NR gNB/cell <NUM> may either filter the list (e.g., remove the blocked cells) before transmitting it to UE <NUM>, or directly transmit the list to UE <NUM> without any modification.

After NR gNB/cell <NUM> acquires the information regarding which NR gNBs/cells and eLTE eNBs/cells support UE <NUM>'s network slice/service request, NR gNB/cell <NUM> may respond to UE <NUM> with RRC message (e.g., RRC Connection Reject or RRC Connection Reconfiguration), where the RRC message includes information such as target NR gNB/cell/beam or LTE eNB/cell or eLTE eNB/cell ID, and/or a list of suitable NR gNB/cell/beam IDs and/or LTE eNB/cell IDs and/or eLTE eNB/cell IDs, and/or specific preamble of the target NR gNB/cell or LTE eNB/cell or eLTE eNB/cell, and/or target NR SS block/burst/burst set configuration, and/or a list of suitable NR SS block/burst/burst set configurations, as illustrated in <FIG>. The SS block/burst/burst set may include synchronization signals and/or reference signals for UE <NUM> to do measurements. Thus, UE <NUM> may perform measurements to the target NR gNB/cell/beam or LTE eNB/cell or eLTE eNB/cell or a list of NR gNBs/cells/beams or LTE eNBs/cells or eLTE eNBs/cells. Moreover, with the information of preamble, the target node/cell may regard UE <NUM> as a special UE, and provide UE <NUM> with privilege during the random access procedure. Providing the beam information and the SS block/burst/burst set configurations to UE <NUM> may be beneficial, when different beams can support different network slices/services (different numerology/TTI length configurations) in NR.

In other implementations, NR gNB/cell <NUM> may directly select a target NR gNB/cell or a target LTE eNB/cell or a target eLTE eNB/cell for UE <NUM>, and send an RRC message (e.g., RRC Connection Reject or RRC Connection Reconfiguration) including the cell ID, and/or preamble, and/or beam ID (if supported), and/or SS block/burst/burst set configuration (if supported) of a target NR gNB/cell or a target LTE eNB/cell or a target eLTE eNB/cell to UE <NUM>. UE <NUM> may perform MCG-related/SCG-related procedures (e.g., handover to another master node that supports the required/requested network slice/service, the inter-MN handover without the change of the secondary node, beam change/addition/modification, or secondary node change/addition/ modification so that the new/target secondary node supports the required/requested network slice/service) for slice-driven mobility management. In the present implementation, UE <NUM> may have multi-connectivity with a number of base stations to support the network slice/service. It is noted that the NR gNBs/cells and eLTE eNBs/cells chosen by NR gNB/cell <NUM> may at least provide the network slice function, and optionally provide UE <NUM>'s specific request network slice/service.

In other implementations, the RRC message for rejection may include a prohibit timer. The prohibit timer may be activated either when NR gNB/cell <NUM> sends the RRC message for rejection or when UE <NUM> receives the RRC message for rejection. Once the prohibit timer is activated, UE <NUM> may not be allowed to camp to NR gNB/cell <NUM> until the prohibit timer expires. In other implementations, once the prohibit timer is activated, UE <NUM> cannot request the same network slice/service from any base station until the prohibit timer expires. The prohibit timer stops either when the prohibit timer expires or when NR gNB/cell <NUM> updates its network slice support (e.g., UE <NUM> may constantly monitor the network slice support while the prohibit timer is running).

<FIG> is a diagram illustrating an NR gNB/cell accepting network slice inquiry, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> sends a network slice/service request through an RRC message, such as an RRC Message for Request (e.g., including UE ID, Slice IDs/NS Indication/Slice Bitmap) to NR gNB/cell <NUM>. In action <NUM>, NR gNB/cell <NUM> reads the RRC message including UE1702's network slice/service request, and decides to provide such network slice/service on its own. NR gNB/cell <NUM> may reply to UE <NUM> with an RRC message, such as an RRC Message for Connection Setup (e.g., RRC Connection Setup or RRC Reconfiguration) to build a connection or reconfigure the connection for the required/requested network slice/service between UE <NUM> and NR gNB/cell <NUM>, as shown in <FIG>. Upon receiving the RRC message, UE1702 responds with another RRC message, such as an RRC Message for Complete Connection (e.g., RRC Connection Setup Complete or RRC Reconfiguration Complete) to show its acknowledgement as shown in <FIG>.

<FIG> is a diagram illustrating an MCG bearer and an MCG split bearer (e.g., a split bearer) with an NR gNB/cell as a master node, according to an exemplary implementation of the present disclosure. When NR gNB/cell <NUM> is a master node, the network slice/service can be realized through an MCG bearer on its own or through an MCG split bearer if a secondary node supports the RAN part of slicing, as shown in <FIG>. As shown in <FIG>, NR gNB/cell <NUM> may be a master node in an MCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. eLTE eNB/cell <NUM> may be a secondary node in the SCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The MCG bearer and MCG split bearer in <FIG> may be substantially similar to the MCG bearer and MCG split bearer, respectively, as described with reference to <FIG>. Thus, the details of the MCG bearer and MCG split bearer are omitted for brevity.

<FIG> is a diagram illustrating an SCG bearer and an SCG split bearer (e.g., a split bearer) with an NR gNB/cell as a secondary node, according to an exemplary implementation of the present disclosure. When NR gNB/cell <NUM> is a secondary node, an SCG bearer may be used to provide the network slice/service. Also, an SCG split bearer can be used to provide the network slice/service if a master node supports the RAN part of slicing, as shown in <FIG>.

As shown in <FIG>, eLTE eNB/cell <NUM> may be a master node in the MCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. NR gNB/cell <NUM> may be a secondary node in an SCG, and may include SDAP layer <NUM>, PDCP layer <NUM>, RLC layer <NUM>, MAC layer <NUM>, and PHY layer <NUM>. The SCG bearer and SCG split bearer in <FIG> may be substantially similar to the SCG bearer and SCG split bearer, respectively, as described with reference to <FIG>. Thus, the details of the SCG bearer and SCG split bearer are omitted for brevity.

An NR gNB/cell may broadcast its network slice capability either via minimum System Information (SI) or via other SI. If the information is provided by other SI, it can be broadcast or unicast by the NR gNB/cell. Upon receiving the SI, a UE can identify whether it is able to perform the required/requested network slice/service to the secondary node. The NR gNB/cell may be in an MCG or an SCG. That is, the signaling for delivering the system information can be sent via an MCG SRB, an MCG split SRB, an SCG SRB, or an SCG split SRB. In another implementation, the system information message generated by the NR gNB/cell as a secondary node is embedded in a master node's RRC message, and delivered by the master node's RRC message.

<FIG> is a diagram illustrating providing network slice via minimum SI, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, NR gNB/cell <NUM> may broadcast minimum SI including Slice IDs and/or NS Indication and/or Slice Bitmap. If slice IDs are broadcast, NR gNB/cell <NUM> directly informs the system (including UE <NUM>) what network slices/services are supported. Thus, UE <NUM> can identify by itself whether the required/requested network slice/service is supported by NR gNB/cell <NUM>. When NR gNB/cell <NUM> broadcasts an NS Indication, NR gNB/cell <NUM> reveals its network slice capability instead of the exact supported network slices/services. As such, UE <NUM> can further inquire/request NR gNB/cell <NUM> about what exact network slice/service is supported via dedicated signaling if UE <NUM> has the network slice/service requirement. When NR gNB/cell <NUM> broadcasts a slice bitmap, NR gNB/cell <NUM> explicitly reveals the specific supported network slices. In action <NUM>, UE <NUM> may identify whether the required/requested network slice service is supported by NR gNB/cell <NUM> based on the minimum SI broadcast by NR gNB/cell <NUM>.

<FIG> is a diagram illustrating providing network slice via other SI, according to an exemplary implementation of the present disclosure. In <FIG>, NR gNB/cell <NUM> may broadcast or unicast its network slice capability and/or the supported network slice/service via other SI (e.g., on demand SI). In action <NUM>, UE <NUM> may first request the other SI from NR gNB/cell <NUM> (e.g., via an SI Request message including NS Indication, which means UE <NUM> needs more SI information regarding to the network slice/service from the NR gNB/cell. ) In action <NUM>, NR gNB/cell <NUM> may send a reply message including NR gNB/cell <NUM>'s supported network slices/services (e.g., via Slice ID and/or Slice Bitmap) and/or its network slice capability (e.g., via NS Indication), in the other SI. In action <NUM>, UE <NUM> may identify and/or determine whether the required/requested network slice/service is supported by NR gNB/cell <NUM> based on the other SI from NR gNB/cell <NUM>.

<FIG> is a diagram illustrating a neighboring cell's network slice via other SI, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, UE <NUM> may send an RRC message (e.g., SI Request, such as an RRCSystemInfoRequest message) to NR gNB/cell <NUM>, where the RRC message may include NS Indication and/or Slice Bitmap and/or Slice IDs for asking network slice support, or NS Indication and/or Slice Bitmap and/or Slice IDs of neighboring NR gNBs/cells/beams and/or eLTE eNBs/cells for the network slice support from neighboring nodes/cells/beams. NR gNB/cell <NUM> may reveal the neighboring gNBs/cells/beams' and/or eLTE eNBs/cells' supported network slices/services (e.g., with the combination of Slice IDs and/or Slice Bitmap and neighboring NR gNB/cell/beam and/or eLTE eNB/cell IDs) and/or the network slice capabilities (e.g., the combination of NS Indication and neighboring NR gNB/cell/beam and/or eLTE eNB/cell IDs, or only the neighboring NR gNB/cell/beam and/or eLTE eNB/cell IDs which support) in the other SI. In action <NUM>, UE <NUM> may determine and/or identify whether the required/requested network slice/service is supported by any neighboring NR gNBs/cells/beams and/or eLTE eNBs/cells, based on which UE <NUM> may further perform the mobility management procedures such as cell (re)selection, measurement, SCG-related procedures (e.g., change/addition/modification of secondary node), and MCG-related procedures (e.g., handover to another master node which supports the required/requested network slice/service, or the inter-MN handover without the change of the secondary node).

In some exemplary implementations, the UE may first check whether the serving NR gNB/cell or eLTE eNB/cell can support the required/requested network slice or network slice capability. If the serving NR gNB/cell or eLTE eNB/cell cannot support the required/requested network slice or network slice capability, the UE may further ask for information of neighboring NR gNBs/cells/beams and eLTE eNBs/cells for network slice support (e.g., as shown in <FIG>). In some exemplary implementations, the UE may request for information of neighboring NR gNBs/cells/beams and eLTE eNBs/cells for network slice support via preamble, and/or MSG <NUM>, and/or MSG <NUM>. The NR gNB/cell may response with MSG <NUM> and/or MSG <NUM> and/or specific configured resources. It is noted that control signaling exchanged among the NR gNB/cell and the neighboring NR gNBs/cells and eLTE eNBs/cells may occur through/in Xx/Xn interface. The control signaling exchange may involve information exchange such as NS Indication of neighboring NR gNBs/cells/beams and/or eLTE eNBs/cells, and/or Slice IDs or Slice Bitmaps of neighboring NR gNBs/cells/beams and/or eLTE eNBs/cells, and/or the list of neighboring NR gNB/cell/beam and/or eLTE eNB/cell IDs.

When a UE may recognize that the required/requested network slice/service is not supported by its master node and/or the secondary node, the UE, the master node, the secondary node, the core network, or any combination thereof may trigger mobility management procedures (e.g., intra-MN handover, inter-MN handover, intra-SN handover, inter-SN handover, MCG-related procedures, SCG-related procedures, inter-MN handover without the change of the secondary node, inter-SN handover without the change of the master node, secondary node change/addition/modification, or beam change/addition/modification) to satisfy the UE's required/requested network slice/service. It is noted that the master node and the secondary node can be the NR gNB/cell and/or the eLTE eNB/cell. It is noted that the selected master node or secondary node may or may not support the UE's required network slice/service. For example, the selected master node or secondary node may support the network slice/service, that is not required by the UE. In some implementations, the UE may request the required the network slice/service from the target master node or target secondary node. The result of the mobility management procedures may lead to dual connectivity or multi-connectivity.

The mobility management procedures may also involve information exchange in Xx/Xn interface and NG-C interface, such as UE ID, Slice IDs/Slice bitmap/NS Indication, target NR gNB/cell/beam or LTE eNB/cell or eLTE eNB/cell ID, and/or a list of suitable NR gNB/cell/beam IDs and/or LTE eNB/cell IDs and/or eLTE eNB/cell IDs, and/or specific preamble of the target NR gNB/cell or LTE eNB/cell or eLTE eNB/cell, and/or target NR SS block/burst/burst set configuration, and/or a list of suitable NR SS block/burst/burst set configurations.

A UE may perform handover to another master node, while the secondary node may remain unchanged. The UE may measure the signal from a couple of NR gNBs/cells and/or eLTE eNBs/cells, which support the UE's required/requested network slice/service or support the network slice. The list of the NR gNBs/cells and/or eLTE eNBs/cells may be provided by the master node and/or the secondary node, for example, in the form of a list of (neighboring) NR gNB/cell and/or eLTE eNB/cell IDs/objects, which support the required/requested network slice/service and/or the network slice capability. The list of NR gNBs/cells and/or eLTE eNBs/cells, to which the UE measures signal, may be preconfigured. For example, the UE may be preconfigured to know on which frequency the required/requested network slice/service is provided.

Based on the measurement report, the UE may select the target master node on its own and report the decision to the source master node. In another implementation, the UE may report the measurement result to the source master node, and allow the source master node to select a target master node. It is noted that signaling in Xx/Xn interface among the source master node, the target master node, the source secondary node, and the target secondary node (if needed) may be utilized.

A UE may select or reselect a secondary node, intra-SN handover to another secondary node, or modify the existing secondary node, to support the required/requested network slice/service, while the master node may remain unchanged. The secondary node may be selected by the UE or by the master node based on measurement results. The reselected secondary node(s) may also be assigned by the core network (e.g., <NUM>-CN). For example, the UE may measure a number of NR gNBs/cells that support the required/requested network slice/service. The information of the number of NR gNBs/cells may be provided by the master node or the source secondary node to the UE, for example, in the form of a list of (neighboring) NR gNB/cell IDs/objects. In other cases, the UE may be preconfigured to know on which frequency the required/requested network slice/service is supported. It is noted that the selected secondary node may be NR gNBs/cells and/or eLTE eNBs/cells.

Based on the measurement report, the UE may select the target secondary node and report the decision to the source master node. In another implementation, the UE may report the measurement result to the source master node, and allow the source master node to select a target master node. It is noted that signaling in Xx/Xn interface among the source master node, the source secondary node, and the target secondary node may be utilized. In some implementations, the NG-C signaling exchange between the master node and the <NUM>-CN may be also needed. Thereafter, the corresponding RRC message exchange between the UE and the master node, or between the UE and the target secondary node, may be utilized.

A UE may add a new secondary node that supports the required/requested network slice/service. The added secondary node may be an NR gNB/cell or an eLTE eNB/cell. The added secondary node may be selected by the UE, by the master node, by the existing secondary nodes, or by the core network (e.g., <NUM>-CN). The selection may be based on the measurement result and/or the matched supported network slice/service. For example, the UE may measure a number of NR gNBs/cells and/or eLTE eNBs/cells that support the required/requested network slice/service. The information of the number of NR gNBs/cells and/or eLTE eNBs/cells may be provided by the master node or the existing secondary nodes or the core network to the UE, for example, in the form of a list of (neighboring) NR gNB/cell IDs/objects and/or (neighboring) eLTE eNB/cell IDs/objects. In other cases, the UE may be preconfigured to know on which frequency the required/requested network slice/service is supported.

Based on the measurement report, the UE may select the new secondary node on its own and report the decision to the source master node and/or the existing secondary nodes. In another implementation, the UE may report the measurement result to the source master node and/or the existing secondary nodes, and allow the source master node and/or the existing secondary nodes to select a target master node. It is noted that the signaling in Xx/Xn interface among the source master node, the existing secondary nodes, and the added secondary node may be utilized. The NG-C signaling between the master node and the 5GC may also be needed. Thereafter, the corresponding RRC message exchange between the UE and the master node, and/or between the UE and the added secondary node and/or between the UE and the existing secondary nodes, may be utilized.

In some implementations, when the master node cannot support the network slice/service but the secondary node can, or when the secondary node cannot support the network slice/service but the master node can, the mobility management procedures in Cases 4A, 4B, and 4C can also be performed.

<FIG> is a diagram illustrating an eLTE eNB/cell broadcasting its network slice capability, according to an exemplary implementation of the present disclosure. As illustrated in <FIG>, in action <NUM>, eLTE eNB/cell <NUM>, as a master node or a secondary node, may broadcast Slice IDs and/or NS Indication and/or Slice Bitmap. When slice IDs are broadcast, eLTE eNB/cell <NUM> may directly inform UE <NUM> what network slices/services are supported. In action <NUM>, UE <NUM> may determine or identify whether the required/requested network slice/service is supported by the eLTE eNB/cell. When an NS Indication is broadcast, eLTE eNB/cell <NUM> may reveal its network slice capability instead of the exact network slice/service supported. UE <NUM> may further inquire or request the eLTE eNB/cell <NUM> about exactly what network slice/service is supported by eLTE eNB/cell <NUM> via dedicated signaling if UE <NUM> has the network slice/service requirement. When a slice bitmap is broadcast, eLTE eNB/cell <NUM> may explicitly reveal the specific supported network slices. It is noted that the broadcast message (e.g., System Information Block (SIB)) may be delivered via an MCG SRB, an MCG split SRB, an SCG SRB, or an SCG split SRB.

An idle/inactive UE camps or selects/reselects a cell of a suitable RAT that supports the required/requested network slice/service.

<FIG> is a diagram illustrating cell (re)selection based on network slice, according to an exemplary implementation of the present disclosure. In action <NUM>, a UE's Non Access Stratum (NAS) first identifies a selected PLMN (Public Land Mobile Network) and the equivalent PLMNs. The UE's NAS is preconfigured to have the information of which RAT/frequency band supports the network slice or even specific network slice/service. The UE's NAS forwards the information to the Access Stratum (AS). As such, the UE' AS with network slice requirement monitors and measures signal from/on the RATs/frequency bands. In <FIG>, in action <NUM>, the UE's NAS or AS identifies the required/requested network slice/service and/or the network slice support (e.g., via slice IDs and/or NS Indication and/or Slice Bitmap). In action <NUM>, the UE searches the RATs/frequency bands on which the required/requested network slice/service and/or network slice capability are supported. It is noted that the RATs/frequency bands that the UE monitors on may be associated with the selected PLMN or the equivalent PLMNs. In other implementations, the AS may try to receive/measure all RATs/frequency bands, and acquire relative slicing information. After collecting the slicing information, the AS forwards the information to the NAS, which decides which RATs/frequency bands are appropriate. Thereafter, the NAS notifies its decision to the AS, and perform RRC connection establishment with the corresponding RAT/frequency. It is noted that the AS may filter out the RATs/frequency bands with signal quality below a predetermined threshold.

A UE is (pre)configured with a list of barred cells, which cannot support network slice and/or specific network slice/service. In some implementations, the UE is (pre)configured with a list of barred cells, which cannot generally support the network slices. In some implementations, the UE is (pre)configured with a list of barred cells for each specific network slice. For example, for each slice ID, there is a list of barred cells. The UE may be (pre)configured with the relationship between a portion (or all) of the slices and their corresponding lists of barred cells. The list of barred cells can be a list of barred cells' IDs. The list may be preconfigured and/or modified when the UE receives the broadcast information from NR gNBs/cells and eLTE eNBs/cells about their network slice supports. With the list, after the UE may determine the PLMNs and performs measurement, the suitable cells to camp on can be selected based on the list of barred cells.

When an eLTE eNB/cell needs to support a network slice, the eLTE eNB/cell may perform inter-system intra-RAT handover, as shown in <FIG>, for example, from Case 500D in <FIG> to Case 500B in <FIG>. <FIG> is a diagram illustrating inter-system intra-RAT handover, according to an exemplary implementation of the present disclosure. In the inter-system intra-RAT handover, the S1-C and NG-C interfaces may involve slice-related information exchange, which includes, for example, capability of network slice support and/or the types of network slices (e.g., RAN slice ID and/or CN slice ID). In the inter-system intra-RAT handover, NAS signaling carried in the RRC message including the slice information may be utilized in a Uu interface, when the eLTE eNB/cell changes the serving core network of the UE. In some implementations, the UE may connect with EPC <NUM> and <NUM>-CN <NUM> simultaneously. In such case, the UE may connect with a source CN (e.g., EPC <NUM> or <NUM>-CN <NUM>) through eLTE eNB <NUM>. eLTE eNB <NUM> may assist the UE to connect with a target CN while the original connection with the source CN is still kept by eLTE eNB <NUM>. This situation may happen when the UE's required/requested network slice is served by a specific CN. For example, the UE is connected with EPC <NUM>, then wants to activate a service, such as URLLC, which can be provided only by <NUM>-CN <NUM>'s network slice. The UE needs to inform eLTE eNB <NUM> that it is capable to connect with EPC <NUM> and <NUM>-CN <NUM> simultaneously. eLTE eNB <NUM> may also need to inform the UE that eLTE eNB <NUM> is capable to connect with EPC <NUM> and <NUM>-CN <NUM> simultaneously. Once the UE is connected with EPC <NUM> and <NUM>-CN <NUM> simultaneously, the UE may keep two different upper layers (e.g., one NAS layer for EPC <NUM>, and another NAS layer for <NUM>-CN <NUM>). In another example, the UE may have one upper layer but two separate configurations (e.g., two instances, one for EPC <NUM>, and another one for <NUM>-CN <NUM>). That is, a shared upper layer (e.g., NAS) and two independent configurations (e.g., instances) for EPC <NUM> and <NUM>-CN <NUM>.

A UE may perform mobility management to change its anchor node to a target NR gNB/cell or eLTE eNB/cell that supports the UE's required/updated network slice. In some implementations, the network slice in the source NR gNB/cell or eLTE eNB/cell is maintained. The UE may maintain the original network slice in the source NR gNB/cell or eLTE eNB/cell.

In some implementations, when the UE performs mobility management to change the anchor to the target NR gNB/cell or eLTE eNB/cell, which supports the UE's required/requested network slice, the configuration for new radio bearers (e.g., SDAP/PDCP/RLC/MAC/PHY configuration) to realize the network slice in the target NR gNB/cell or eLTE eNB/cell is provided to the UE by the source/target NR gNB/cell or eLTE eNB/cell.

In some implementations, the configuration for new radio bearers (e.g., SDAP/PDCP/RLC/MAC/PHY configuration) to realize the UE's request network slice in the target NR gNB/cell or eLTE eNB/cell may be provided to the UE by the source NR gNB/cell or eLTE eNB/cell. The UE may keep the control plane anchor to the source/target NR gNB/cell or eLTE eNB/cell.

<FIG> is a diagram illustrating RAN notification area update with network slice support, according to an exemplary implementation of the present disclosure. For example, when UE <NUM> is in RRC_ INACTIVE state and has some network slices, a RAN notification area update procedure may consider UE <NUM>'s network slice requirements. When RRC_INACTIVE UE <NUM> moves out of the RAN notification area, and finds the received RAN area ID and/or NR gNB/cell ID (e.g., from target NR gNB/cell/RAN <NUM>) is not in its RAN notification area (e.g., source NR gNB/cell/RAN <NUM>), in action <NUM>, UE <NUM> may send an RRC message (e.g., RRC Resume Request) including its UE ID and/or source NR gNB/cell <NUM>'s ID and/or source RAN area ID and/or NS Indication/Slice ID/Slice Bitmap to target NR gNB/cell/RAN <NUM>. The cause of the RRC message sent by the UE may be "RAN notification area update request". Source NR gNB/cell <NUM>'s ID and source RAN area ID are in the UE's original RAN notification area. In action <NUM>, target NR gNB/cell/RAN <NUM> may perform UE context retrieval and UE authentication and RAN notification area inquiry with <NUM>-CN <NUM> and/or source NR gNB/cell/RAN <NUM>. Xx/Xn signaling and NG-C signaling including UE <NUM>'s ID and UE <NUM>'s slice ID, NS Indication, and/or Slice Bitmap may be utilized for target NR gNB/cell/RAN <NUM> to confirm UE <NUM>'s status, to retrieve UE <NUM>'s context from source NR gNB/cell/RAN <NUM>, and to coordinate with <NUM>-CN <NUM> and/or source NR gNB/cell/RAN <NUM> for the list of possible NR gNBs/cells/RANs with UE <NUM>'s corresponding network slice support and requirement from <NUM>-CN <NUM> and/or source NR gNB/cell/RAN <NUM>. Therefore, the RRC message (e.g., RAN notification area update message) sent from target NR gNB/cell/RAN <NUM> to UE <NUM> may include the IDs of NR gNB/cell IDs and/or RAN area which support UE <NUM>'s network slice. The cause of this RRC message may be RAN notification area update. For example, the RAN notification area update message sent to UE <NUM> includes the IDs of NR gNB/cell and/or RAN area, which support UE <NUM>'s network slice requirements and/or the specific network slice. That is, when <NUM>-CN <NUM> and/or NR gNB/cell RAN <NUM>/<NUM> determine the RAN notification area for UE <NUM>, only the NR gNBs/cells and/or RANs which can support UE <NUM>'s network slice requirement and/or the specific slice are considered.

In some implementations, for example, the NR gNBs/cells/RANs in the updated RAN notification area may not support the UE's network slice requirement. Thus, the UE may not camp to the NR gNBs/cells/RANs in the updated RAN notification area which does not support its network slice. That is, whatever the updated RAN notification area is, the inactive UE may only camp to an NR gNB/cell provided in the updated RAN notification area message, where the NR gNB/cell supports the UE's network slice requirement and/or the specific network slice. In such case, the RAN notification area determined by the core network and/or NR gNB/cell for the inactive UE is not based on the UE's network slice requirement and/or specific slice. However, the UE may only camp to the NR gNB/cell and/or RAN in the indicated RAN notification area, which can support the UE's network slice requirement. The UE may determine whether an NR gNB/cell supports the UE's network slice requirement and/or the specific network slice based on the NR gNB/cell's broadcast message, which may include NS Indication and/or Slice IDs and/or Slice Bitmap.

In the aforementioned cases <NUM>-<NUM>, whenever the UE responds to the NR gNB/cell and/or the eLTE eNB/cell with Slice IDs/NS Indication/Slice Bitmap/UE IDs/NS Indication of neighboring NR gNBs/cells/beams/ NS Indication of neighboring eLTE eNBs/cells, the UE may utilize MSG <NUM>, MSG <NUM> or MSG <NUM>, which may also be utilized for communications between the LTE eNB/cells and the UE.

<FIG> illustrates a block diagram of a node for wireless communication, in accordance with various aspects of the present application. As shown in <FIG>, node <NUM> may include a transceiver <NUM>, a processor <NUM>, a memory <NUM>, one or more presentation components <NUM>, and at least one antenna <NUM>. The node <NUM> may also include an RF spectrum band module, a base station communications module, a network communications module, and a system communications management module, input/output (I/O) ports, I/O components, and power supply (not explicitly shown in <FIG>). Each of these components may be in communication with each other, directly or indirectly, over one or more buses <NUM>.

The transceiver <NUM> having a transmitter <NUM> and a receiver <NUM> may be configured to transmit and/or receive time and/or frequency resource partitioning information. In some implementations, the transceiver <NUM> may be configured to transmit in different types of subframes and slots including, but not limited to, usable, non-usable and flexibly usable subframes and slot formats.

The node <NUM> may include a variety of computer-readable media. Computer-readable media can be any available media that can be accessed by the node <NUM> and include both volatile and non-volatile media, removable and non-removable media. By way of example, and not limitation, computer-readable media may comprise computer storage media and communication media. Computer storage media includes both volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data.

Computer storage media includes RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices. Computer storage media does not comprise a propagated data signal. Communication media typically embodies computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer-readable media.

The memory <NUM> may include computer-storage media in the form of volatile and/or non-volatile memory. The memory <NUM> may be removable, non-removable, or a combination thereof. Exemplary memory includes solid-state memory, hard drives, optical-disc drives, and etc. As illustrated in <FIG>, The memory <NUM> may store computer-readable, computer-executable instructions <NUM> (e.g., software codes) that are configured to, when executed, cause the processor <NUM> to perform various functions described herein, for example, with reference to <FIG>. Alternatively, the instructions <NUM> may not be directly executable by the processor <NUM> but be configured to cause the node <NUM> (e.g., when compiled and executed) to perform various functions described herein.

The processor <NUM> may include an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an Application Specific Integrated Circuit (ASIC), and etc. The processor <NUM> may include memory. The processor <NUM> may process the data <NUM> and the instructions <NUM> received from the memory <NUM>, and information through the transceiver <NUM>, the base band communications module, and/or the network communications module. The processor <NUM> may also process information to be sent to the transceiver <NUM> for transmission through the antenna <NUM>, to the network communications module for transmission to a core network.

One or more presentation components <NUM> presents data indications to a person or other device. Exemplary presentation components <NUM> include a display device, speaker, printing component, vibrating component, and etc..

Claim 1:
A method for a user equipment, UE, the method comprising:
identifying (<NUM>), by a non-access stratum, NAS, of the UE while the UE is in a Radio Resource Control, RRC, inactive, RRC_Inactive, or RRC idle, RRC_Idle, state, a selected Public Land Mobile Network, PLMN, and one or more equivalent PLMNs;
identifying (<NUM>), by the NAS of the UE, a required network slice/service of the UE based on Single Network Slice Selection Assistance Information, S-NSSAI, wherein the S-NSSAI uniquely identifies the required network slice/service;
measuring signals (<NUM>), by an access stratum, AS, of the UE while the UE is in the RRC_inactive or RRC_Idle state, from one or more radio access technologies, RATs, and frequency bands on which the required network slice/service identified by the S-NSSAI is supported, wherein the NAS of the UE is preconfigured with information of the one or more RATs and frequency bands associated with one or more network slices/services identified by the S-NSSAI; and
selecting, by the NAS of the UE, a cell that supports the required network slice/service of the UE based on the measured signals.