WO2018153432A1

WO2018153432A1 - Techniques for slice activation in multi-slice networks

Info

Publication number: WO2018153432A1
Application number: PCT/EP2017/053915
Authority: WO
Inventors: Ömer BULAKCI; Panagiotis SPAPIS; Alexandros KALOXYLOS
Original assignee: Huawei Technologies Duesseldorf Gmbh
Priority date: 2017-02-21
Filing date: 2017-02-21
Publication date: 2018-08-30
Also published as: CN110326340B; CN110326340A

Abstract

The disclosure relates to a User Equipment (UE) (210), comprising a processor, configured: to receive an activation command for at least one idle Slice (110) of a plurality of Slices, wherein the activation command orders a connection establishment for the at least one idle Slice (110); and to set the UE (210) to an active state for enabling the connection establishment for the at least one idle Slice (110). The disclosure further relates to a Core Network (CN) system (230), comprising: an Inter Slice Control Agent (ICA-CN) (235) configured to gather context information from at least one Slice of a plurality of Slices, a User Equipment (UE) (210) is associated with or can be associated with; and at least one CN instance (231, 232), configured to transmit a connection request to the UE (210), the connection request requesting the UE (210) to establish a connection for at least one idle Slice (110) of the plurality of Slices. The disclosure further relates to a radio access network (RAN) entity (220).

Description

Techniques for slice activation in multi-slice networks

TECHNICAL FIELD

The present disclosure relates to techniques for slice activation in multi-slice networks, in particular in Next Generation Radio networks.

BACKGROUND

Network Slicing is one of the key building blocks of the fifth generation mobile and wireless communication networks (5G), aka New Radio (NR) or new radio access technology (RAT) or next generation wireless networks, aiming especially at vertical industries integration. The network slice can be defined as a logical network (providing Telecommunication Services and Network Capabilities) including access network (AN) and core network (CN) , see 3GPP TR 23.799 "Study on Architecture for Next Generation System (Release 14)," vO.7.0 (2016-08). 3^rd Generation Partnership Project (3GPP) is standardizing Network Slicing from both Core Network (CN) and radio access network (RAN) sides, see 3GPP TR 23.799 and 3GPP TR 38.801 "Study on New Radio Access Technology; Radio Access Architecture and Interfaces (Release 14)," vl .0.0 (2016-12). A user equipment (UE) can access multiple network slices. When these multiple network slices per UE are logically separated, signaling cost can increase dramatically along with an increase of control plane latency due to parallel operation of control functionalities in these network slices. SUMMARY

It is the object of the invention to provide a concept for reducing signaling latency and/or signaling cost in multi-slice networks. This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

The invention is based on the idea to utilize context information available in one slice instance of a multi-slice network to improve the functionalities in another. This invention presents slice activation techniques, where in the CN, UE Context construction can be based on information elements received from slice CN Instances for a given UE. In particular, the core network can store information through which the active slices can be inferred such that, e.g., a direct connection to UE is possible via one of the active slices and via this direction connection another idle slice is activated. Further, information, through which the search space of gNBs (i.e. base stations) can be optimized for paging and thereby identifying the UE, can be stored in the core network. The information elements can comprise state information, e.g., State Vectors based on core network States like ECM states and radio access network (RAN) states like RRC states, and/or Serving gNB(s), and/or Connection histories and tracking area lists (TALs).

This invention provides techniques for slice activation to optimize (e.g., to minimize) the signaling cost and control plane (CP) latency when a UE can obtain services from one or more specific network slice instances, e.g., of one operator. In particular, the invention provides techniques, when a UE has access to multiple network slices, e.g., with different connection requirements, to utilize context information available in one slice instance to improve the functionalities in another. This solution allows optimized activation (paging free or optimized paging) of the other slice instance based on this context information. It can minimize the signaling cost and control plane latency due to parallel-running control functionalities in multiple slices.

The rationale behind the employment of this invention is that this invention presents inter- slice information exchange among the slices associated with one UE (or also referred to as slice instances or network slices herein) and associated optimization to reduce mobility management (MM) signaling. In particular, the devices, methods and systems presented in this invention utilize context information available in one slice instance or slice instances to improve the functionalities, e.g., mobility management functionality in another slice instance or slice instances; enable optimized activation (e.g., paging free or optimized paging) of the other slice instance based on such context information and associated mechanism(s); and minimize the signaling cost and control plane latency due to parallel-running control functionalities in multiple slices, e.g., mobility management.

In the following, methods for enabling slice activation are described that may be based on connection request or activation request or that may be based on paging. On this basis, a slice activation can be understood from a UE perspective, wherein a communication is to be established for the UE via the slice to be activated such that the UE can obtain services of that slice. Activating a UE when a packet for that UE arrives to network from the internet, e.g., to the serving gateway (S-GW) in long-term evolution (LTE) networks, can be performed via paging. That is, the UE is in idle state, e.g., radio resource control (RRC)- IDLE, and paging can be used to get an RRC-IDLE UE switching to RRC-CONNECTED state. RRC states refer to the state of the UE on the RAN while, on the CN side, states of the UE refer to evolved packet system (EPS) connection management (ECM) states, such as, ECM-CONNECTED and ECM-IDLE. RRC states and ECM states together can define the EPS Mobility Management (EMM) states, e.g., EMM Deregistered (e.g., the UE is detached from the network) and EMM Registered (e.g., the UE is attached to the network). The network entity, e.g., mobility management entity (MME), knows the location of the UE on a tracking area (TA) basis, where a TA can consist of multiple cells served by base stations (BSs). The paging message for the IDLE UE is sent to these cells and the UE is paged according to its paging cycle.

Multi-slice networks as described in this disclosure may apply the concept of network slicing. The network slicing is an emerging concept, e.g., targeted for 5G networks. Activating a slice when a UE can access more than one slice is one essential problem. There can be different mechanisms that can be used for activating a slice. One possible approach can be applying the paging-like procedure for each network slice to which UE can access. There can be further optimization for such paging mechanism. For example, via blanket paging scheme, all the cells included in the tracking area (TA) can be paged simultaneously, and via sequential paging scheme the associated TA can be divided into several Paging Areas. When an incoming call arrives, Paging Areas can be paged one by one until the UE is found. In another approach, the paging area can be determined based on the last connection of a device and how close it is to the border areas so as to reach the device with the first paging message.

When paging is utilized for each slice separately, such activation of each slice individually (parallel operation of control functionalities) can result in significant Mobility Management (MM) Signaling as well as suboptimal latency values. That is, the delay constraints may not be fulfilled according to the slice requirements and/or the signaling cost can be increased significantly. Consequently, the slice requirements may not be fulfilled. By applying slice activation techniques as presented in this disclosure, signaling delay can be reduced and delay constraints according to the slice requirements can be fulfilled. The devices, systems and methods described hereinafter are based on communication devices, e.g. Small Cells and Relay Nodes. Small Cells are low-power nodes whose transmit (Tx) power is typically lower than macro node and can take the form of Planned/Unplanned pico-cells, femto-cells and relays. Relaying is standardized in LTE (Long Term Evolution) Release 10 and is also considered to be part of the fifth generation (5G) new radio (NR) Standardization 3GPP TR 38.801 : "Study on new RAT; Radio Access Architecture and Interfaces (Release 14)". The devices described herein may be implemented in wireless communication networks, in particular communication networks based on mobile communication standards such as LTE, in particular LTE-A and/or OFDM-based system and 5G. The devices described herein may further be implemented in a mobile device (or mobile station or User

Equipment (UE)), for example in the scenario of device-to-device (D2D) communication where one mobile device communicates with another mobile device. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

D2D communications in cellular networks is defined as direct communication between two mobile devices or mobile users without traversing the Base Station (BS) or eNodeB or gNB or the core network. D2D communications is generally non-transparent to the cellular network and can occur on the cellular spectrum (i.e., inband) or unlicensed spectrum (i.e., outband). D2D communications can highly increase spectral efficiency, improve throughput, energy efficiency, delay, and fairness of the network. The transmission and reception devices described herein may be implemented in mobile devices

communicating under D2D scenarios. However, the transmission and reception devices described herein may also be implemented in a base station (BS) or eNodeB or gNB.

The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio frequency lying in a range of about 3 kHz to 300 GHz. The frequency range may correspond to frequencies of alternating current electrical signals used to produce and detect radio waves. The devices described herein may include small cells and may use network slicing. Small cells and network slicing as described hereinafter are two key enablers of 5G, e.g. as described by Next Generation Mobile Networks (NGMN) Alliance: "5G White Paper", Feb. 2015 and it is very likely that they will be standardized for 5G RAN (radio access network) also known as NR (next radio) in 3GPP. Small-cells can improve coverage and/or capacity, e.g. as highlighted in Next Generation Mobile Networks (NGMN) Alliance: "5G White Paper", Feb. 2015. Furthermore, Network Slicing is a composition of network functions, specific function settings and associated resources and can have different impacts on radio access network (RAN) design. In RAN, various slice-based target key performance indicators (KPIs) can comprise, e.g., throughput / spectral efficiency for enhanced mobile broadband (eMBB) communications, high reliability and low latency for ultra-reliable and low latency communications (URLLC), and connection density for massive machine-type communications (mMTC). Slices may have different requirements in terms of throughput and latency, which necessitate enabling different operations for different types of traffic to meet certain KPIs.

The devices and systems described herein may include processors. In the following description, the term "processor" describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor can process software or firmware or applications etc.

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

ICA: Inter-Slice Context Control Agent

ICA-CN: Inter-Slice Context Control Agent - Core Network

ICA-UE: Inter-Slice Context Control Agent - User Equipment

DSC: Dynamic Small Cell

RN: Relay Node

RACH: Random Access Channel

RAN: Radio Access Network

RRC: Radio Resource Control

MM: Mobility Management CN: Core Network

NR: New Radio

TA: Tracking Area

TAL: Tracking Area List

KPI: Key Performance Indicator

D2D: Device-to-device

DL: Downlink

UL: Uplink

UP: User Plane

CP: Control Plane

BS: Base Station, eNodeB, eNB, gNB

UE: User Equipment, e.g. a mobile device or a machine-type communication

Device or a car

5G: 5^th generation, e.g., based on 3GPP standardization

LTE: Long Term Evolution

RF: Radio Frequency

MBB: Mobile BroadBand

eMBB: enhanced Mobile BroadBand

URLLC: Ultra-Reliable Low Latency Communications

MTC: Machine Type Communication

uMTC ultra-reliable MTC

TX: Transmit

RX: Receive

OAM: Operation and maintenance

EPS: Evolved Packet System

EMM: EPS Mobility Management

ECM: EPS Connection Management

S-GW: Serving gateway According to a first aspect, the invention relates to a User Equipment (UE), comprising a processor, configured: to receive an activation command for at least one idle Slice of a plurality of Slices, via at least one active Slice of the plurality of Slices, wherein the activation command orders a connection establishment for the at least one idle Slice; and to set the UE to an active state for enabling the connection establishment for the at least one idle Slice. Such a UE can reduce the signaling latency when applied in multi-slice networks because activation for an idle Slice can be signaled through an active Slice, thereby saving signaling commands and reducing latency.

In a first possible implementation form of the UE according to the first aspect, the processor is configured: to initiate the connection establishment with a Radio Access Network (RAN) for the at least one idle Slice. This provides the advantage that the RAN network can control the initiation of connection establishment.

In a second possible implementation form of the user equipment according to the first aspect as such or according to the first implementation form of the first aspect, the processor is configured: to receive the activation command via a first connection control instance of the UE associated with the at least one active Slice; and to initiate the connection establishment via a second connection control instance of the UE associated with the at least one idle Slice. This provides the advantage that the first and second connection control instances can cooperate for initiating the connection establishment, thereby reducing the signaling load.

In a third possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured: to initiate the connection establishment via a single connection control instance of the UE associated with the at least one active Slice and the at least one idle Slice.

This provides the advantage that a single connection control instance, e.g. a master connection control instance, can coordinate connection establishment which can make connection establishment less complicated, e.g., in terms of UE implementation.

In a fourth possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured: to initiate the connection establishment for the at least one idle Slice based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble received along with the activation command or a random preamble. This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. The RACH procedures can be used to exchange necessary information and to establish the connection.

In a fifth possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured: to initiate the connection establishment for the at least one idle Slice based on paging-free non Random Access Channel (RACH) procedures (ALT2) using information elements for providing information about the connection establishment received along with the activation command, in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI).

This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. Necessary information can be provided by the information elements described above without RACH procedures, e.g., sending a preamble to the RAN entity. Hence, the signaling load can be reduced and a faster connection establishment can be attained.

In a sixth possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured to enable the connection establishment for the at least one idle Slice of the plurality of Slices based on the activation command received via the at least one active Slice of the plurality of Slices.

This provides the advantage that the activation command can be forwarded via the active Slice to the idle Slice. Thus, signaling messages can be reduced.

In a seventh possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the UE comprises a memory, configured to store a state of the plurality of Slices, and the processor is configured to run an Inter-Slice Context Control Agent (ICA-UE) which is configured to exchange information, in particular control commands and information elements for connection establishment, between different Slices.

This provides the advantage that the ICA-UE can use the necessary information about the Slices for exchanging messages between different Slices. Due to the memory storing the information about the Slices, a latency for connection establishment can be reduced.

In an eighth possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor is configured to run: at least one first connection control instance associated with the at least one active Slice for receiving the activation command; and at least one second connection control instance associated with the at least one idle Slice for initiating the connection establishment for the at least one idle Slice. This provides the advantage that the at least two connection control instances can interact in order to improve connection establishment, e.g., in terms of latency and/or signaling load.

In a ninth possible implementation form of the user equipment according to the first aspect as such or according to any of the preceding implementation forms of the first aspect, the processor comprises: a single connection control instance associated with the at least one active Slice and the at least one idle Slice, for initiating the connection establishment for the at least one idle Slice. This provides the advantage that a single connection control instance, e.g. a master connection control instance, can coordinate connection establishment which can simplify connection establishment procedure.

According to a second aspect, the invention relates to a Radio Access Network (RAN) Entity, in particular a Base Station (BS), comprising a processor, configured: to connect a UE, in particular a UE according to the first aspect as such or according to any of the implementation forms of the first aspect, to at least one active Slice of a plurality of Slices; and to transmit an activation command to the UE via at least one active Slice of the plurality of Slices, wherein the activation command orders the UE to establish a connection for at least one idle Slice of the plurality of Slices. Such a RAN entity can reduce the signaling latency when applied in multi-slice networks because activation for an idle Slice can be signaled through an active Slice, thereby saving signaling commands and reducing latency.

In a first possible implementation form of the RAN entity according to the second aspect, the activation command orders the UE to enter an active state for enabling the connection establishment for the at least one idle Slice. This provides the advantage that less signaling can be necessary to bring the UE in an active state.

In a second possible implementation form of the RAN entity according to the second aspect as such or according to the first implementation form of the second aspect, the processor is configured to establish the connection with the UE for the at least one idle Slice.

This provides the advantage that the processor provides an efficient mechanism to establish the connection with the UE for an idle Slice, e.g., in terms of signaling efficiency.

In a third possible implementation form of the RAN entity according to the second aspect as such or according to any of the preceding implementation forms of the second aspect, the processor is configured to request the UE for connection establishment for the at least one idle Slice based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble or a random preamble.

This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. The RACH procedures can be used to exchange necessary information for the connection establishment.

In a fourth possible implementation form of the RAN entity according to the second aspect as such or according to the first or second implementation forms of the second aspect, the processor is configured to request the UE for connection establishment for the at least one idle Slice based on paging-free non Random Access Channel (RACH) procedures (ALT2) sending information elements for providing information about the connection establishment, in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI).

This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. Necessary information can be provided by the information elements described above without RACH procedures, e.g., sending a physical RACH (PRACH) preamble to the RAN entity. Hence, the signaling load and/or latency can be reduced. According to a third aspect, the invention relates to a Core Network (CN) system, comprising: an Inter Slice Control Agent (ICA-CN) configured to gather context information from at least one Slice of a plurality of Slices, a User Equipment (UE) is associated with; and at least one CN instance, configured to transmit a connection request to the UE, the connection request requesting the UE to establish a connection for at least one idle Slice of the plurality of Slices.

Such a CN system can reduce the signaling latency when applied in multi-slice networks because activation for an idle Slice can be signaled through an active Slice, thereby saving signaling commands and reducing latency. A CN instance can comprise slice-tailored CN functionalities, e.g., mobility management. CN instances corresponding to different slices or slice instances may also have shared CN functionalities. Further, the context information for a UE can be collected from the CN instances of the slices where the UE is associated with or can be associated with. In a first possible implementation form of the CN system according to the third aspect, the at least one CN instance is configured: to infer at least one of base stations to be used for paging the UE; and to gather information, in particular from the ICA-CN, by which a number of candidate base stations used for the paging can be reduced, in particular information of CN states, serving base station(s), connection histories and/or tracking area lists of the plurality of Slices.

This provides the advantage that the number of base stations to be used for paging can be reduced thereby reducing latency and saving signaling messages. In a second possible implementation form of the CN system according to the third aspect, the at least one CN instance is configured: to transmit the connection request based on paging-free procedures via the at least one active Slice to the UE based on priority levels of the plurality of Slices.

This provides the advantage that different priorities can be implemented for realizing the multi-slice network. For example, a high-priority slice activation can be performed via another slice with similar priority level, which can, e.g., help fulfill the latency requirements of the high-priority slice.

In a third possible implementation form of the CN system according to the third aspect as such or according to any of the preceding implementation forms of the third aspect, the at least one CN instance is configured: to request the UE to establish the connection for the at least one idle Slice based on paging-free non Random Access Channel (RACH) procedures (ALT2) when connecting the at least one idle Slice to a same base station or hypercell and/or when location information of the UE is known or can be estimated.

This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. Necessary information can be provided by the information elements described above without RACH procedures, e.g., sending a PRACH preamble to the RAN entity. Hence, the signaling load and/or latency can be reduced.

In a fourth possible implementation form of the CN system according to the third aspect as such or according to any of the preceding implementation forms of the third aspect, the at least one CN instance is configured: to request the UE to establish the connection for the at least one idle Slice based on paging-free Random Access Channel (RACH) procedures (ALT1 ) when connecting the at least one idle Slice to a same base station or to neighboring base stations. This provides the advantage that no paging is needed for connection establishment, reducing the signaling load and/or latency. The RACH procedures can be used to exchange necessary information for the connection establishment.

According to a fourth aspect, the invention relates to a method for enabling connection establishment for an idle Slice of a User Equipment (UE), the method comprising: receiving an activation command for at least one idle Slice of a plurality of Slices, wherein the activation command orders a connection establishment for the at least one idle Slice; and setting the UE to an active state for enabling the connection establishment for the at least one idle Slice.

Such a method can reduce the signaling latency and/or signaling load when applied in multi- slice networks because activation for an idle Slice can be efficiently performed based on the context information, in particular, collected by ICA and received through ICA, thereby reducing latency and/or signaling load.

According to a fifth aspect, the invention relates to a communication system, comprising: a user equipment according to the first aspect as such or according to any of the

implementation forms of the first aspect; a Radio Access Network (RAN) Entity according to the second aspect as such or according to any of the implementation forms of the second aspect; and a CN system according to the third aspect as such or according to any of the implementation forms of the third aspect.

Such a communication system can reduce the signaling latency and/or signaling load in multi-slice networks because activation for an idle Slice can be efficiently performed based on the context information, in particular, collected by ICA and received through ICA, thereby reducing latency and/or signaling load.

BRIEF DESCRIPTION OF THE DRAWINGS Further embodiments of the invention will be described with respect to the following figures, in which:

Figs. 1 a and 1 b show schematic diagrams illustrating a multi-slice network utilizing a method for activating an idle slice of a user equipment (UE), here a 5G car as an example, that has access or can have access to multiple slices, here eMBB and uMTC slices as examples, where Figure 1 a shows paging messages sent through the cells in the tracking area of the UE via the idle slice and Fig. 1 b shows sending a connection request or activation request for the idle slice via the active slice; Fig. 2 shows a schematic diagram of a multi-slice network 200 according to an implementation form, where a UE 210 is associated with two slices, wherein each slice is characterized, e.g., by a connection control instance 21 1 at UE 210, a connection control instance 221 at a RAN entity 220, a CN instance#1 231 comprising user plane (UP) and control plane (CP) functionalities at a CN system 230, and ICA (also referred to as ICA- CN) 235, which can communicate with CN instance#1 231 and CN lnstance#2 232 at the CN system 230, and ICA-UE 213 at the UE 210, which can communicate with the connection control instance 21 1 and a connection control instance 212; Fig. 3 shows a schematic diagram of a multi-slice network 300 according to an implementation form where slice activation according to a first alternative (ALT1 ) is illustrated;

Fig. 4 shows an exemplary signal flow diagram 400 of slice activation for the multi-slice network 300 of Fig. 3;

Fig. 5 shows a schematic diagram of a multi-slice network 500 according to an implementation form where slice activation according to a second alternative (ALT2) is illustrated;

Fig. 6 shows an exemplary signal flow diagram 600 of slice activation for the multi-slice network 500 of Fig. 5;

Fig. 7 shows a schematic diagram of a multi-slice network 700 according to an implementation form where some core network (CN) functions are shared by slices in the CN;

Fig. 8 shows a schematic diagram of a multi-slice network 800 according to an implementation form where mobility management (MM) functions are shared by slices in the CN;

Fig. 9 shows a schematic diagram of a multi-slice network 900 according to an implementation form where control plane (CP) functions are shared by slices in the CN; Fig. 10 shows a schematic diagram of a multi-slice network 1000 according to an implementation form where slice activation according to an optimized paging is performed, when at least one slice (also referred to as slice instance) is active; Fig. 1 1 shows an exemplary signal flow diagram 1 100 of slice activation for the multi-slice network 1000 of Fig. 10;

Fig. 12 shows a schematic diagram of a multi-slice network 1200 according to an implementation form where slice activation according to an optimized paging is performed, when all slices of the UE, i.e., the UE is associated to or can be associated to, (also referred to as slice instance) are idle;

Fig. 13 shows an exemplary signal flow diagram 1300 of slice activations for the multi- slice network 1200 of Fig. 12;

Fig. 14 shows a schematic diagram of a multi-slice network 1400 according to an implementation form where slice activation according to an optimized paging is performed, when all slices of the UE, i.e., the UE is associated to or can be associated to, (also referred to as slice instance) are idle and there is one control connection, like radio resource control (RRC) connection, to the UE in the RAN;

Fig. 15 shows an exemplary signal flow diagram 1500 of slice activation for the multi-slice network 1400 of Fig. 14; Fig. 16 shows a block diagram of an exemplary user equipment (UE) 210 according to an implementation form;

Fig. 17 shows a block diagram of an exemplary radio access network (RAN) entity 220 according to an implementation form;

Fig. 18 shows a block diagram of an exemplary core network (CN) system 230 according to an implementation form; and

Fig. 19 shows a schematic diagram illustrating an exemplary method 1900 for enabling connection establishment for an idle slice of a UE according to an implementation form. DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

In the following multi-slice networks, i.e. communication networks with multiple network slices are described. A "network slice" is a fully operational logical network containing all required protocols and network resources. In some deployments, network slices can be considered as completely individual networks which however belong to the same network operator. This gives to the network operator the ability to share resources among the network slices for meeting the respective slice demands. In some deployments, network slices may share some user plane (UP) and/or control plane (CP) functionalities and/or the same pool of network resources may be shared by the network slices, e.g., a pool of radio resources, such as, frequency and time resources.

Figs. 1 a and 1 b show schematic diagrams illustrating a multi-slice network utilizing a method for activating an idle slice of a user equipment (UE) 107, here a 5G car as an example, that has access or can have access to multiple slices, here eMBB 1 10 and uMTC 120 slices as examples, where Figure 1 a shows paging messages sent through the cells in the tracking area of the UE via the idle slice 109a and 109b, and Fig. 1 b shows sending a connection request or activation request 132 for the idle slice 1 10 via the active slice 120. Herein, a slice activation can be understood from a UE perspective, wherein a communication is to be established for the UE via the slice to be activated such that the UE can obtain services of that slice.

In Fig. 1 , an example implementation of the method is depicted. 5G car 107 is provided as an example UE 107, where the 5G car may access to multiple slices, such as, ultra- reliable machine type communications (uMTC, e.g., for autonomous driving service) slice 120 and enhanced mobile broadband (eMBB, e.g., video streaming service) slice 1 10. In Fig. 1 a, the paging 109a, 109b is applied separately for each slice, i.e., when a packet 101 arrives to the idle slice 1 10 for the UE 107, to move the UE 107 from idle state to connected state, the UE 107 is paged 109a, 109b according to the tracking area 108 and the base stations (depicted as gNBs) 106a, 106b, 106c therein. In Fig. 1 b, the high-level implementation of the presented method and system is depicted, where the connection request 132 or activation request for the idle slice 1 10 is communicated via the active slice 120, when a packet 101 arrives to the idle slice 1 10 for the UE 107, based on the inter- slice context exchange 130 and the associated mechanisms that will be detailed in the following. In this example, the paging mechanism 109a, 109b shown in Fig. 1 a is not utilized.

In the following figures Inter-Slice Context Control Agents (ICAs) are shown on UE side and on CN side. The Inter-Slice Context Control Agent on UE side is also referred to as ICA-UE while the Inter-Slice Context Control Agent on CN side is also referred to as ICA- CN.

Fig. 2 shows a schematic diagram of a multi-slice network 200 according to an

implementation form, where a UE 210 is associated with two slices and can communicate with a RAN entity 220 exemplarily residing at the macro BS, e.g. the base stations 106a, 106b, 106c depicted in Figs. 1 a and 1 b. The UE 210 may be integrated into a 5G car as depicted in Figures 1 a and 1 b. One example network structure along with the presented ICA (also referred to as ICA-CN) and ICA-UE functional entities 235, 213, respectively, where the considered method can be applied to, is illustrated in Fig. 2. In Fig. 2, Slice#1 that may correspond to active slice 120 depicted in Figs. 1 a and 1 b, is characterized by a CN Instance #1 , 231 with specific user plane (UP) 235 and control plane (CP) 234 functions on the CN side 230 and RRC#1 , 221 on the RAN side 220, while Slice#2 that may correspond to idle slice 1 10 depicted in Figs. 1 a and 1 b, characterized by a CN Instance #2, 232 with specific user plane (UP) 237 and control plane (CP) 236 functions on the CN side 230 and RRC#2, 222 on the RAN side 220. ICA 235 logically lies between CN lnstance#1 , 231 and CN lnstance#2, 232 on the CN side 230 and ICA-UE 213 logically lies between RRC#1 , 21 1 and RRC#2, 212 on the UE side 210. In this particular example, Slice#1 , 120 is active (e.g., the UE is in RRC-CONNECTED and ECM-CONNECTED and EMM Registered states) while Slice#2, 1 10 is idle (e.g., the UE is in RRC-IDLE, ECM-IDLE and EMM Registered states). A packet 101 for the UE 210 arrives to the CN Instance #2, 232 of the Slice#2, 1 10 in this example. In the following, unless otherwise stated, depending in the slice activation mechanism, ALT1 refers to the case of "With Random Access", where the UE 210 applies random access procedures, e.g., to switch from RRC-IDLE to RRC-CONNECTED, and ALT refers to the case of "Without Random Access," where the UE 210 does not apply random access procedures but the presented mechanism, e.g., to switch from RRC-IDLE to RRC- CONNECTED. Herein, a connection control instance, e.g., RRC#1 221 , can perform similar or modified functions like RRC and, thus, is marked as RRC in the figures and in the text. The state of the UE with respect to a slice on the RAN side is marked by RRC states, e.g., RRC-IDLE and RRC-CONNECTED, while the state of the UE with respect to a slice on the CN side is marked by ECM states, e.g., ECM-CONNECTED and ECM- IDLE.

Fig. 3 shows a schematic diagram of a multi-slice network 300 according to an

implementation form where slice activation according to a first alternative (ALT1 ) is illustrated. Fig. 4 shows an exemplary signal flow diagram 400 of slice activation for the multi-slice network 300 of Fig. 3.

One embodiment of the present invention is described with the aid of Fig. 3 and Fig. 4. Thereon, the different steps of the disclosed method are marked with numbers starting from 0 to 7. The different steps in Figs. 3 and 4 are also marked with reference signs to delimit these steps from the steps described below with respect to the further figures. In Fig. 3, for illustration purposes, only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to Figures 1 a, 1 b and 2, while as shown in Fig. 4, the UE 210 can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to Figures 1 a, 1 b and 2. When a UE 210 is associated with multiple slices and multiple RRC connections, RRC and/or ECM state information is exchanged among different slices to optimize MM (mobility management) signaling via Inter-slice Context control Agent (ICA) 235 (also referred to as ICA-CN herein). In particular, in Step 0 (300a, 300b, 300c, 300d), ECM State information for the UE 210 is collected from the available CN Instances (CN instances to which UE 210 may have access and/or not, for example CN instances 231 , 232 in this example). Based on this information, ECM state vector for the UE 210 can be constructed by the ICA 235. Further, RRC state vector can also be constructed based on the RRC state information for the UE 220 collected from the available connection control instances in RAN (e.g., RRC#1 221 and RRC#2 222). The ECM State information may be transmitted to the ICA 235 (a) upon the attach of a new UE 210 to a slice, and (b) periodically so as to update the ECM State Vector in case a UE 210 becomes not operational and/or (c) when there is a change in at least one piece of the information. In Fig. 3, one of the slices is active (for example, for Slice#1 , 120 UE 210 is in RRC/ECM Connected State and for Slice#2, 1 10 UE 210 is in RRC/ECM Idle State), and a packet 101 arrives to Slice#2, 1 10 in RRC/ECM Idle state. The following steps are executed:

• Steps (1 and 2) (301 , 302) CN lnstance#2, 232 will retrieve Active CN Instances from ICA 235 and (3) requests Connection for the UE 210 for "Slice#2, 1 10 according to priorities or priority levels" via the selected CN lnstance#1 , 231 . The description of "according to priorities" is provided in the following.

· Step (3) (303) CN lnstance#1 , 231 sends Connection Request for Slice#2, 120 to the RAN 220 (RRC#1 , 221 ).

• Step (4) (304) RAN 220 (RRC#1 , 221 ) sends Activate Command to UE 210 on Slice#1 , 120 RRC Connection.

Step (5) (305) The Activate Command sent in (4) (304) will be sent to Slice#2, 1 10 at UE 120 via ICA-UE 213. It is noted optionally a "Dedicated Preamble" for the UE 120 can be sent to enable non-contention based random access.

Step (6 and 7) (306, 307) UE 120 starts with Random Access, e.g., on the physical random access channel (PRACH) using RACH procedures, and performs RRC Connection 306. NG2/3 Connection is then established 307 (e.g., like S1 bearer and S1 signaling connection in LTE). NG2/3 interfaces are being described by 3GPP (see,

3GPP TR 23.799 "Study on Architecture for Next Generation System (Release 14)," V14.0.0 (2016-12)).

In Steps 1 and 2 above (301 , 302), CN lnstance#1 , 231 is selected based on the priorities or priority levels. When the UE 210 can have access to more than 2 Slices and there are at least 2 active Slices, then the Slice which shall communicate the "Connection Request and/or Activate Command" can be determined based on the Slice Priorities. Priority can be defined relative to the idle Slice which shall be activated. For example,

• if a higher priority slice is to be activated, select the Active Slice with closest priority · if a lower priority slice is to be activated, select the Active Slice with least priority.

The priority of a slice can be determined based on, e.g.:

• Service Level Agreement (SLA) for different Slices, and/or

• Latency requirements (e.g., uMTC slice can have higher priority than eMBB slice due to stringent latency requirements) and/or

· Congestion level of the Slice.

Furthermore, estimated latency for a slice activation via a selected active slice can also be taken into account in selecting the active slice.

ALT1 may preferably be applied in a scenario of heterogeneous networks (e.g., where small cells are deployed in the same area with macrocells), where each slice connection may connect to a different cell based on the slice requirements. For example, an eMBB slice connection of the UE 210 may be established via mm wave (mmW) small cell, while an uMTC slice connection of the UE 210 may be established via macrocell. Here, two options can be implemented:

· Sending only activate command and, thereafter, the UE 210 performs contention- based random access;

• Sending activate command with a dedicated preamble and UE 210 performs non- contention based random access.

o In this case, dedicated preambles can be allocated to the gNB of the active slice and few determined neighboring cells where the idle slice may connect to. That is, RRCs are aware of these preambles at the serving gNB of the active slice and also neighboring gNBs.

Note that the methods described in this disclosure can be generalized to the case where packets arrive to multiple idle slices.

Fig. 5 shows a schematic diagram of a multi-slice network 500 according to an

implementation form where slice activation according to a second alternative (ALT2) is illustrated. Fig. 6 shows an exemplary signal flow diagram 600 of slice activation for the multi-slice network 500 of Fig. 5. In Fig. 5, for the sake of simplicity only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to Figures 1 a, 1 b, 2, 3 and 4, while as shown in Fig. 6, the UE 210 can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to Figures 1 a, 1 b, 2, 3 and 4.

When ALT2 is employed instead of ALT1 , the following steps are performed. The different steps of the disclosed method are marked with numbers starting from 0 to 8. The different steps in Figs. 5 and 6 are also marked with reference signs to delimit these steps from the steps described below with respect to the further figures. Steps 0, 1 , and 2 (500a, 500b, 501 , 502) can be performed as in the case of ALT1 as described above with respect to Figures 3 and 4. The steps as of (3) (503) are as follows.

• Step (3) (503) CN lnstance#1 , 231 sends Connection Request/Set-Up for Slice#2, 1 10 to the RAN 220 (RRC#1 , 221 ).

Step (4) (504) RRC Configuration for Slice#2, 1 10 is retrieved from RRC#2, 222 by RRC#1 , 221 based on Step (3) (503), and in Step (5) (505) RAN 220 (RRC#1 , 221 ) sends RRC Connection Set-Up for Slice#2 to UE 210.

Step (6) (506) the information elements sent in (5) (505) will be sent to Slice#2, 1 10 at UE 210 via ICA-UE 213. It is be noted that information elements, such as, Timing

Advance (TA), Cell Radio Network Temporary Identity, C-RNTI, can be sent, if Slice#2, 1 10 can be served, e.g., by the same gNB. This can include, for example, radioResourceConfigDedicated which is necessary to establish signaling radio bearer 1 (SRB1 ) for RRC#2, 222 connection establishment.

· Steps (7 and 8) (507, 508) RRC Connection Complete 507 is sent to RRC#2, 222 and then NG2/3 Connection is established 508 (e.g., like S1 bearer and S1 signaling connection in LTE) upon receiving of non-access stratum (NAS) acknowledgement (ACK) for Activation (e.g., like initial UE message in LTE). ALT2 may preferably be applied in the following scenarios:

• HyperCell: In a hypercell, a plurality of base stations or access points can coordinate to form a large-area cell and, thus, creating a big virtual cell from the UE 210 perspective. Thus, both Slices 1 10, 120 can connect to the same hypercell. In this case, RRC Connection Set-up/Reconfiguration can be sent, and there may be no need for the random access. • Macrocell-only Deployment: Both Slices 1 10, 120 can connect to the same macrocell. In this case, RRC Connection Set-up/Reconfiguration can be sent, and there may be no need for the random access.

• Location Information Available: If the UE location is available (e.g., 5G Car) or can be estimated within a desired accuracy, the timing advance can be estimated within cyclic prefix length, and there may be no need for random access.

Depending on the network structure, the above mechanisms can be applied as they are or part of the steps may be performed. Some example implementations are depicted in the following amendments.

Fig. 7 shows a schematic diagram of a multi-slice network 700 according to an

implementation form where some core network (CN) functions are shared by slices in the CN.

In Fig. 7, for the sake of simplicity only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures. The UE 210, however, can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures.

In one network structure, some of the CN functions, such as the control plane (CP) functions may be shared among slices, as illustrated in Fig. 7. In such structure, the ICA 235 (also referred to as ICA-CN) may be located in the entity of the shared (or common) control block 705. In this case, MM functions 703, 704 of different CN Instances 701 , 702 can reside at the dedicated control blocks of different slices, e.g. Slice 1 (120) or Slice 2 (1 10) as described above with respect to the preceding figures. For example, it can be expected that Location Management (as part of MM) of a vehicle to anything (V2X) slice or uMTC slice to be much more different than that of an eMBB slice. Further, in this structure, the mechanisms and steps described above with respect to the preceding figures can be applied straightforwardly to this structure.

Fig. 8 shows a schematic diagram of a multi-slice network 800 according to an

implementation form where mobility management (MM) functions are shared by slices in the CN. In Fig. 8, for the sake of simplicity only two slices 1 10, 120 are depicted too, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures. The UE 210, however can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures.

In one network structure, MM function(s) may be shared 705 among slices in the CN 230, as illustrated in Fig. 8. In such structure, part of the mechanisms and steps described above can be applied to this structure (for both ALT1 and ALT2 as described above). If the UE 210 can have access to more than two slices and there are different MM functions, the mechanisms and steps described above can be applied straightforwardly to such structure. The slices with the common MM 235 can be considered as one virtual slice and this virtual slice and the other slices with different MM functions can communicate according to the aforementioned steps with the aid of Fig. 3 to Fig. 6.

For example, Step 1 (801 ) may correspond to Step 3 (303, 503) described above with respect to Figures 3 to 6; Step 2 (802) may correspond to Step 4 (304) described above with respect to Figs. 3 and 4 or to Step 5 (505) described above with respect to Figures 5 and 6; Step 3 (803) may correspond to Step 5 (305) described above with respect to Figs. 3 and 4 or to Step 6 (506) described above with respect to Figures 5 and 6; Step 4 (804) may correspond to Step 6 (306) described above with respect to Figs. 3 and 4 or to Step 7 (507) described above with respect to Figures 5 and 6. Fig. 9 shows a schematic diagram of a multi-slice network 900 according to an

implementation form where control plane (CP) functions 705 are shared by slices in the CN 230.

In Fig. 9, for the sake of simplicity only two slices 1 10, 120 are depicted too, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures. The UE 210, however can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures. In one network structure, CP functions 705 may be shared among slices in the CN 230, as illustrated in Fig. 9. In such structure, part of the mechanisms and steps described above can be applied to this structure (for both ALT1 and ALT2 as described above). If the UE 210 can have access to more than two slices and there are different MM functions, the mechanisms and steps described above can be applied straightforwardly to such structure. The slices with the common CN CP functions 705 can be considered as one virtual slice, and this virtual slice and the other slices with different MM functions can communicate according to the aforementioned steps with the aid of Fig. 3 to Fig. 6. For example, Step 1 (801 ) may correspond to Step 3 (303, 503) described above with respect to Figures 3 to 6; Step 2 (802) may correspond to Step 4 (304) described above with respect to Figs. 3 and 4 or to Step 5 (505) described above with respect to Figures 5 and 6; Step 3 (803) may correspond to Step 5 (305) described above with respect to Figs. 3 and 4 or to Step 6 (506) described above with respect to Figures 5 and 6; Step 4 (804) may correspond to Step 6 (306) described above with respect to Figs. 3 and 4 or to Step 7 (507) described above with respect to Figures 5 and 6.

Fig. 10 shows a schematic diagram of a multi-slice network 1000 according to an implementation form where slice activation according to an optimized paging is performed, when at least one slice (also referred to as slice instance) is active. Fig. 1 1 shows an exemplary signal flow diagram 1 100 of slice activation for the multi-slice network 1000 of Fig. 10.

One embodiment is described with the aid of Fig. 10 and Fig. 1 1 . Thereon, the different steps of the disclosed method are marked with numbers starting from 0 to 4.

The different steps in Figs. 10 and 1 1 are also marked with reference signs to delimit these steps from the steps described with respect to the other figures. In Fig. 10, for the sake of simplicity only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures, while as shown in Fig. 1 1 , the UE 210 can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures.

When a UE 210 is associated with multiple slices 1 10, 120 and multiple RRC connections 21 1 , 212, RRC and/or ECM state information and/or serving gNB information, connection history, and/or tracking area and/or tracking area lists (TALs) are exchanged among different slices to optimize MM signaling via Inter-slice Context control Agent (ICA) 235. In particular, in Step 0 (1000a, 1000b, 1000c), the aforementioned pieces of information for the UE 210 are collected from the available CN Instances 231 , 232 (CN instances 231 , 232 to which UE 210 may have access and/or not). Based on this information, UE context can be constructed by the ICA 235 (also referred to as ICA-CN). These pieces of information may be transmitted to the ICA 235 (a) upon the attach of a new UE 210 to a slice, and (b) periodically so as to update the UE context, and/or (c) when there is a change in at least one piece of the information. In Fig. 10, one of the slices is active (for example, for Slice#1 , 120 UE 210 is in RRC/ECM Connected State and for Slice#2, 1 10 UE 210 is in RRC/ECM Idle State), and a packet 101 arrives to Slice#2, 1 10 in RRC/ECM Idle state. The following steps are executed:

• Steps (1 and 2) (1001 , 1002) CN lnstance#2, 232 will retrieve serving gNB of the UE 210 via the active CN Instance #1 , 231 from ICA 235 based on the context collected by ICA 235 in Step (0) (1000a, 1000b, 1000c).

Step (3) (1003) CN lnstance#2, 232 sends Paging Command to the serving gNB and/or a determined set of neighboring cells.

• Step (4) (1004) The UE 210 is paged at these gNB(s) for Slice#2, 1 10. It is noted that if the CN Instance #2 State is like EMM Deregistered, CN Instance #2, 232 can retrieve UE Context from ICA 235 (e.g., International Mobile Subscriber Identity, I MSI, and Global unique Temporary ID, GUTI). When UE 210 may have access to multiple slices and different slices are connected to different cells, all of these serving gNBs may be paged, e.g. as described above for the scenario with respect to Fig. 1 a. Also, a subset of the gNBs may be paged taking into account the slice requirements, e.g., gNB support for the slice type, slice or slice instance.

Fig. 12 shows a schematic diagram of a multi-slice network 1200 according to an implementation form where slice activation according to an optimized paging is performed, when all slices of the UE (also referred to as slice instance) are idle. Fig. 13 shows an exemplary signal flow diagram 1300 of slice activation for the multi-slice network 1200 of Fig. 12.

One embodiment of the present invention is described with the aid of Fig. 12 and Fig. 13. Thereon, the different steps of the disclosed method are marked with numbers starting from 0 to 5. The different steps in Figs. 12 and 13 are also marked with reference signs to delimit these steps from the steps described below with respect to the other figures. In Figs. 12 and 13, for the sake of simplicity only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures. However, with respect to Figures 12 and 13, both slice #1 , 120 and slice #2, 1 10 are in an idle state. The UE 210, however, can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures. When a UE 210 is associated with multiple slices 1 10, 120 and multiple RRC connections 221 , 222, RRC and/or ECM state information and/or serving gNB information, connection history, and/or tracking area and/or tracking area lists (TALs) are exchanged among different slices, e.g. Slice #1 , 120 and Slice #2, 1 10, to optimize MM signaling via Inter-slice Context control Agent (ICA) 235. In particular, in Step 0 (1200a, 1200b, 1200c), the aforementioned pieces of information for the UE 210 is collected from the available CN Instances 231 , 232 (i.e. CN instances 231 , 232 to which UE 210 may have access and/or not). Based on this information, UE context can be constructed by the ICA 235 (also referred to as ICA-CN). In Fig. 12 and Fig. 13, all of the slices 1 10, 120 of the UE 210 are idle (for example, UE is in RRC/ECM Idle State for all slices to which UE is associated to or can be associated to), and a packet 101 arrives to Slice#2, 1 10. The following steps are executed: • Steps (1 and 2) (1201 , 1202) CN lnstance#2, 232 will retrieve UE context comprising connection history (e.g., movement path of the UE 210 in active mode and tracking area list, TAL) from ICA 235.

Step (3) (1203) MM at CN lnstance#2, 232 determines (or estimates) the gNBs to be used for paging based on, e.g.,

• Overlap of the Tracking Area Lists (TALs) of CN instances 231 , 232, e.g., CN lnstance#1 , 231 and CN lnstance#2, 232 in Fig. 12

Estimated movement path of the UE 210 based on the connection history Estimated gNBs, where the UE 210 possibly resides

· Slice support of the gNBs.

Steps (4 and 5) (1204, 1205) The UE 210 is paged at these determined or estimated gNB(s) for Slice#2, 1 10.

It is noted that due to different activation periods of the slices 1 10, 120, the movement path estimation can be different. Further, the movement path can include information, e.g., the serving gNBs of the UE 210 during the movement, location coordinates of the UE 210 during the movement and/or UE 210 measurements, such as, RSRP and RSRQ. Via context exchange, the optimized path can be found. Also, due to different slice

requirements, TALs of the slices 1 10, 120 can be different.

Fig. 14 shows a schematic diagram of a multi-slice network 1400 according to an implementation form where slice activation according to an optimized paging is performed, when all slices of the UE (also referred to as slice instance) are idle and there is one radio resource control (RRC) connection 1421 to the UE in the RAN. Fig. 15 shows an exemplary signal flow diagram 1500 of slice activation for the multi-slice network 1400 of Fig. 14.

One embodiment of the present invention is described with the aid of Fig. 14 and Fig. 15.

Thereon, the different steps of the disclosed method are marked with numbers starting from 0 to 6. The different steps in Figs. 14 and 15 are also marked with reference signs to delimit these steps from the steps described with respect to the other figures. In Figs. 14 and 15, for the sake of simplicity only two slices 1 10, 120 are depicted, that may correspond to the active slice #1 and idle slice #2 as described above with respect to the preceding Figures.

However, with respect to Figures 14 and 15, both slice #1 , 120 and slice #2, 1 10 are in an idle state. The UE 210, however, can also have access to more slices. The UE 210 may correspond to the UE 210 as described above with respect to the preceding Figures.

When a UE 210 is associated with multiple slices, RRC and/or ECM state information and/or serving gNB information, connection history, and/or tracking area and/or tracking area lists (TALs) are exchanged among different slices to optimize MM signaling via Inter-slice Context control Agent (ICA) 235 (also referred to as ICA-CN). In particular, in Step 0 (1400a, 1400b, 1400c), the aforementioned pieces of information for the UE 210 are collected from the available CN Instances 231 , 232 (CN instances 231 , 232 to which UE 210 may have access and/or not). Based on this information, UE context can be constructed by the ICA 235. In Fig. 14 and Fig. 15, all of the slices of the UE 210 are idle (for example, UE is in RRC/ECM Idle State for all slices to which UE is associated to or can be associated to), and a packet 101 arrives to Slice#2, 1 10. The following steps are executed:

• Steps (1 and 2) (1401 , 1402) CN lnstance#2, 232 will retrieve UE context comprising connection history (e.g., movement path of the UE 210 in active mode and tracking area list, TAL) from ICA, 235. • Step (3) (1403) MM at CN lnstance#2, 232 determines (or estimates) the gNBs to be used for paging based on, e.g.,

Overlap of the Tracking Area Lists (TALs) of CN instances, e.g., CN lnstance#1 , 231 and CN lnstance#2, 232 depicted in Fig. 12,

· Estimated movement path of the UE 210 based on the connection history,

Estimated gNBs, where the UE 210 possibly resides,

Slice support of the gNBs.

Step (4) (1404) Paging command is sent to these determined or estimated gNB(s) for Slice#2, 1 10.

· Step (5) (1405) RRC#2, 1422 (Slave) corresponding to CN lnstance#2, 232 sends request to RRC#1 , 1421 (Master) to page the gNB for Slice#2, 1 10. It is noted that for the sake of simplicity in Fig. 15, two RRCs 1421 , 1422 are shown. For more than two slices, there can be one master 1421 and multiple slave RRCs 1422.

Step (6) (1406) The UE 210 is paged at these determined or estimated gNB(s) for Slice#2, 1 10.

It is noted when the network structure is like the one depicted in Fig. 7, the mechanisms and steps described above can be applied straightforwardly to this structure. Fig. 16 shows a block diagram of an exemplary user equipment (UE) 210 according to an implementation form. The UE 210 includes a processor 1601 , e.g. for processing the functionalities described above with respect to the preceding figures.

The processor 1601 is configured: to receive an activation command 1602, e.g. an activation command 304 as described above with respect to Figures 3 and 4, for at least one idle Slice, e.g. and idle Slice 1 10 as described above with respect to the preceding figures, of a plurality of Slices, via at least one active Slice, e.g. an active Slice 120 as described above with respect to the preceding figures, of the plurality of Slices. The activation command 1602 orders a connection establishment for the at least one idle Slice 1 10. The processor 1602 is further configured to set the UE 210 to an active state for enabling the connection establishment for the at least one idle Slice 1 10.

The processor 1602 may be configured to initiate the connection establishment with a Radio Access Network (RAN), e.g. a RAN 220 as described above with respect to the preceding figures, for the at least one idle Slice 1 10. The processor 1601 may be configured to receive the activation command 1602, 304 via a first connection control instance 21 1 of the UE 210 associated with the at least one active Slice 120, e.g. as described above with respect to the preceding figures. The processor 1601 may be configured to initiate the connection establishment via a second connection control instance 212 of the UE 210 associated with the at least one idle Slice 1 10, e.g. as described above with respect to the preceding figures.

The processor 1601 may be configured to initiate the connection establishment via a single connection control instance, e.g. a single connection control instance 141 1 as described above with respect to Fig. 14, of the UE 210 associated with the at least one active Slice 120 and the at least one idle Slice 1 10.

The processor 1601 may be configured to initiate the connection establishment for the at least one idle Slice 1 10 based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble received along with the activation command or a random preamble 1602, 304, e.g. as described above with respect to the preceding figures. The processor 1601 may be configured to initiate the connection establishment for the at least one idle Slice 1 10 based on paging-free non Random Access Channel (RACH) procedures (ALT2) using information elements for providing information about the connection establishment received along with the activation command 1602, 304, in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI), e.g. as described above with respect to the preceding figures.

The processor 1601 may be configured to enable the connection establishment for the at least one idle Slice 1 10 of the plurality of Slices based on the activation command 1602, 304 received via the at least one active Slice 120 of the plurality of Slices, e.g. as described above with respect to the preceding figures.

The UE 210 may include a memory, configured to store a state of the plurality of Slices. The processor 1601 may be configured to run an Inter-Slice Context Control Agent (ICA- UE), e.g. an ICA-UE 213 as described above with respect to the preceding figures, which is configured to exchange information, in particular control commands and information elements for connection establishment, between different Slices.

The processor 1601 may be configured to run: at least one first connection control instance 21 1 associated with the at least one active Slice 120 for receiving the activation command 1602, 304, e.g. as described above with respect to the preceding figures. The processor 1601 may be configured to run at least one second connection control instance 212 associated with the at least one idle Slice 1 10 for initiating the connection

establishment for the at least one idle Slice 1 10, e.g. as described above with respect to the preceding figures.

The processor 1601 may include a single connection control instance, e.g. a single connection control instance 141 1 as described above with respect to Fig. 14, associated with the at least one active Slice 120 and the at least one idle Slice 1 10, for initiating the connection establishment for the at least one idle Slice 1 10.

Fig. 17 shows a block diagram of an exemplary radio access network (RAN) entity, e.g. a RAN entity 220 as described above with respect to the preceding figures, according to an implementation form. The RAN entity 220 may be a base station, e.g. a gNB 106a, 106b, 106c as described above with respect to Figures 1 a and 1 b. The RAN entity 220 includes a processor 1701 , e.g. for processing the functionalities described above with respect to the preceding figures.

The processor 1701 is configured to connect a UE, e.g. a UE 210 as described above with respect to the preceding figures, to at least one active Slice, e.g. an active Slice 120 as described above with respect to the preceding figures, of a plurality of Slices. The processor 1701 is further configured to transmit an activation command 1602, e.g. an activation command 304 as described above with respect to Figures 3 and 4, to the UE 210 via at least one active Slice 120 of the plurality of Slices. The activation command 1602, 304 orders the UE 210 to establish a connection for at least one idle Slice 1 10 of the plurality of Slices, e.g. as described above with respect to the preceding figures.

The activation command 1602, 304 may order the UE 210 to enter an active state for enabling the connection establishment for the at least one idle Slice 1 10. The processor 1701 may be configured to establish the connection with the UE 210 for the at least one idle Slice 1 10.

The processor 1701 may be configured to request the UE 210 for connection

establishment for the at least one idle Slice 1 10 based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble or a random preamble, e.g. as described above with respect to the preceding figures.

The processor 1701 may be configured to request the UE 210 for connection

establishment for the at least one idle Slice 1 10 based on paging-free non Random

Access Channel (RACH) procedures (ALT2) sending information elements for providing information about the connection establishment, in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI), e.g. as described above with respect to the preceding figures.

Fig. 18 shows a block diagram of an exemplary core network (CN) system, e.g. a CN system 230 as described above with respect to the preceding figures, according to an implementation form. The Core Network (CN) system 230 includes an Inter Slice Control Agent (ICA-CN), e.g. an ICA-CN 235 as described above with respect to the preceding figures, and at least one CN instance, e.g. at least one CN instance 231 , 232 as described above with respect to the preceding figures. The ICA-CN 235 is configured to gather context information from at least one Slice of a plurality of Slices, a User Equipment (UE) 210 is associated with, e.g. as described above with respect to the preceding figures. The at least one CN instance 231 , 232 is configured to transmit a connection request, e.g. a connection request 303, 503 as described above with respect to the preceding figures, to the UE 210. The connection request 303, 503 is requesting the UE 210 to establish a connection for at least one idle Slice 1 10 of the plurality of Slices, e.g. as described above with respect to the preceding figures.

The at least one CN instance 231 , 232 may be configured: to infer at least one base station 220 to be used for paging the UE 210; and to gather information, in particular from the ICA-CN 235, by which a number of candidate base stations, e.g. gNBs 106a, 106b, 106c as described above with respect to Figures 1 a and 1 b, used for the paging 109a, 109b can be reduced, in particular information of CN states, serving base stations, connection histories and/or tracking area lists of the plurality of Slices, e.g. as described above with respect to the preceding figures.

The at least one CN instance 231 , 232 may be configured to transmit the connection request 303, 503 based on paging-free procedures via the at least one active Slice 120 to the UE 210 based on priority levels of the plurality of Slices, e.g. as described above with respect to the preceding figures.

The at least one CN instance 231 , 232 may be configured to request the UE 210 to establish the connection for the at least one idle Slice 1 10 based on paging-free non Random Access Channel (RACH) procedures (ALT2) when connecting the at least one idle Slice 1 10 to a same base station or hypercell and/or when location information of the UE 210 is known, e.g. as described above with respect to the preceding figures.

The at least one CN instance 231 , 232 may be configured to request the UE 210 to establish the connection for the at least one idle Slice 1 10 based on paging-free Random Access Channel (RACH) procedures (ALT1 ) when connecting the at least one idle Slice 1 10 to a same base station or to neighboring base stations, e.g. as described above with respect to the preceding figures.

The CN system 230 can be part of a whole communication system comprising a multi- slice network, e.g. a multi-slice network 200, 300, 500, 700, 800, 900, 1000, 1200, 1400 as described above with respect to the preceding figures. The communication system includes a UE 210 as described above with respect to the preceding figures; a Radio Access Network (RAN) Entity 220 as described above with respect to the preceding figures; and a CN system 230 as described above with respect to the preceding figures. Fig. 19 shows a schematic diagram illustrating an exemplary method 1900 for enabling connection establishment for an idle slice of a UE, e.g. an idle Slice 1 10 of a UE 210 as described above with respect to the preceding figures, according to an implementation form. The method 1900 includes receiving 1901 an activation command for at least one idle Slice 1 10 of a plurality of Slices, wherein the activation command orders a connection establishment for the at least one idle Slice 1 10, e.g. as described above with respect to the preceding figures.

The method 1900 further includes setting 1902 the UE 210 to an active state for enabling the connection establishment for the at least one idle Slice 1 10, e.g. as described above with respect to the preceding figures. Further methods may be related to the processing steps of the RAN entity 220 and the processing steps of the CN system 230 as described above with respect to the preceding figures.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the method 1900 described above with respect to Fig. 19. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the method 1900 described above.

In the following, further example implementations are described. A first example is related to UE Context construction based on information elements received from CN Instances for a given UE, i.e. Information through which the Inter-slice Context exchange Agent (ICA) can infer the active slices such that a direct connection to UE is possible via one of the active slices and via this direction connection of another idle slice is activated and/or information through which the ICA can minimize the search space of gNBs for paging and thereby identify the UE, in particular ECM State Vector based on ECM States, Serving gNBs, Connection histories and TALs.

A second example is related to requesting UE context from the ICA by the idle slice upon receiving a packet. A third example is related to sending Connection Request/Set-Up via the Active Slice based on the Priority of Slices and ECM State Vector, wherein, (Paging Free ALT1 & ALT2) a) If a higher priority slice is to be activated, via the Active Slice with closest priority; b) If a low priority slice is to be activated, via the Active Slice with least priority.

A fourth example is related to sending Connection Set-up from the common RAN (Paging Free ALT2) If the Idle Slice to be activated shall connect to the same gNB or hypercell or location info is known. A fifth example is related to sending the Activate Command (Paging Free ALT1 ) If the Idle Slice to be activate may connect to the same gNB or neighboring gNBs.

A sixth example is related to sending dedicated PRACH preambles to the same gNB and neighboring gNBs (Paging Free ALT1 ).

A seventh example is related to RRC Connection Set-up Signal via ICA-UE at UE side to the Idle Slice (Paging Free ALT2).

An eighth example is related to the seventh, where RRC Connection Set-up is

communicated between Master RRC and Slave RRC over a logical interface, like X2^* depending on the placement of control units (CUs).

A ninth example is related to NAS ACK from UE to the CN Instance #2 (Paging Free ALT2).

A tenth example is related to estimation of the gNBs to be paged by the idle slice to be activated based on the UE context in Claim 1 (Optimized Paging) a) Sending the list of the estimated gNBs to the common RAN; b) Paging the UE based on the estimated gNBs received.

An eleventh example is related to a new functional entity ICA (as described above). A twelfth example is related to a new functional entity ICA-UE (as described above).

A thirteenth example is related to a system of a method and the entities described above. A fourteenth example is related to an implementation where part of the described mechanisms in this disclosure are applied in various combinations of the described steps above. For example, the paging message like in Step (4) 1004 can contain information elements needed for the connection establishment, e.g., Timing Advance (TA), Cell Radio Network Temporary Identity, C-RNTI like in Step (5) 505. This implementation can have the advantage that after receiving the paging message, a non RACH connection establishment can be performed. Furthermore, the paging message can be considered as an activation command upon receiving the paging message UE initiates a connection establishment.

A fifteenth example is related to an implementation where ICA-CN can configure the ICA- UE to perform above-described mechanisms or to perform determined control plane functions. A sixteenth example is related to an implementation where part of the above-mentioned steps are performed by different entities described in this disclosure. For instance, ICA- CN can determine the active slice, through which a connection request for the idle slice to be communicated, based on the collected information elements from slice instances. In a further example, the step of collecting information elements and constructing state vectors can be performed by CN instances of the slices. Such an example can be implemented, e.g., by including an ICA functionality in the different CN instances of the slices or by including the ICA functionality to at least one of the CN instances of the slices. In another example, ICA-CN can send the connection request for the idle slice instance to the determined active slice instance.

Based on the techniques presented in this disclosure, various messages and information elements can require changes in the signaling. Besides, these messages can be transferred over Uu and/or Un interfaces as well as CN interfaces. While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be

appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1 . A User Equipment (UE) (210), comprising a processor (1601 ), configured: to receive an activation command (1602, 304) for at least one idle Slice (1 10) of a plurality of Slices, via at least one active Slice (120) of the plurality of Slices, wherein the activation command (1602, 304) orders a connection establishment for the at least one idle Slice (1 10); and to set the UE (210) to an active state for enabling the connection establishment for the at least one idle Slice (1 10).

2. The UE (210) of claim 1 , wherein the processor (1601 ) is configured: to initiate the connection establishment with a Radio Access Network (RAN) (220) for the at least one idle Slice (1 10).

3. The UE (210) of claim 1 or 2, wherein the processor (1601 ) is configured: to receive the activation command (1602, 304) via a first connection control instance (21 1 ) of the UE (210) associated with the at least one active Slice (120); and to initiate the connection establishment via a second connection control instance (212) of the UE (210) associated with the at least one idle Slice (1 10).

4. The UE (210) of one of the preceding claims, wherein the processor (1601 ) is configured: to initiate the connection establishment via a single connection control instance

(141 1 ) of the UE (210) associated with the at least one active Slice (120) and the at least one idle Slice (1 10).

5. The UE (210) of one of the preceding claims, wherein the processor (1601 ) is configured: to initiate the connection establishment for the at least one idle Slice (1 10) based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble received along with the activation command (1602, 304) or a random preamble.

6. The UE (210) of one of the preceding claims, wherein the processor (1601 ) is configured: to initiate the connection establishment for the at least one idle Slice (1 10) based on paging-free non Random Access Channel (RACH) procedures (ALT2) using information elements for providing information about the connection establishment received along with the activation command (1602, 304), in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI).

7. The UE (210) of one of the preceding claims, wherein the processor (1601 ) is configured to enable the connection establishment for the at least one idle Slice (1 10) of the plurality of Slices based on the activation command (1602, 304) received via the at least one active Slice (120) of the plurality of Slices.

8. The UE (210) of one of the preceding claims, comprising: a memory, configured to store a state of the plurality of Slices, wherein the processor (1601 ) is configured to run an Inter-Slice Context Control

Agent (ICA-UE) (213) which is configured to exchange information, in particular control commands and information elements for connection establishment, between different Slices.

9. The UE (210) of one of the preceding claims, wherein the processor (1601 ) is configured to run: at least one first connection control instance (21 1 ) associated with the at least one active Slice (120) for receiving the activation command (1602, 304); and at least one second connection control instance (212) associated with the at least one idle Slice (1 10) for initiating the connection establishment for the at least one idle Slice (1 10).

10. The UE (210) of one of the preceding claims, wherein the processor (1601 ) comprises: a single connection control instance (141 1 ) associated with the at least one active Slice (120) and the at least one idle Slice (1 10), for initiating the connection establishment for the at least one idle Slice (1 10).

1 1 . A Radio Access Network (RAN) Entity (220), in particular a Base Station (BS), comprising a processor (1701 ), configured: to connect a UE (210), in particular a UE (210) according to one of claims 1 to 10, to at least one active Slice (120) of a plurality of Slices; and to transmit an activation command (1602, 304) to the UE (210) via at least one active Slice (120) of the plurality of Slices, wherein the activation command (1602, 304) orders the UE (210) to establish a connection for at least one idle Slice (1 10) of the plurality of Slices.

12. The RAN entity (220) of claim 1 1 , wherein the activation command (1602, 304) orders the UE (210) to enter an active state for enabling the connection establishment for the at least one idle Slice (1 10).

13. The RAN entity (220) of claim 1 1 or 12, wherein the processor (1701 ) is configured to establish the connection with the UE (210) for the at least one idle Slice (1 10).

14. The RAN entity (220) of one of claims 1 1 to 13, wherein the processor (1701 ) is configured to request the UE (210) for connection establishment for the at least one idle Slice (1 10) based on paging-free Random Access Channel (RACH) procedures (ALT1 ) using a dedicated preamble or a random preamble.

15. The RAN entity (220) of one of claims 1 1 to 13, wherein the processor (1701 ) is configured to request the UE (210) for connection establishment for the at least one idle Slice (1 10) based on paging-free non Random Access Channel (RACH) procedures (ALT2) sending information elements for providing information about the connection establishment, in particular a Timing Advance (TA) and a Cell Radio Network Temporary Identity (C-RNTI).

16. A Core Network (CN) system (230), comprising: an Inter Slice Control Agent (ICA-CN) (235) configured to gather context information from at least one Slice of a plurality of Slices, a User Equipment (UE) (210) is associated with; and at least one CN instance (231 , 232), configured to transmit a connection request (303, 503) to the UE (210), the connection request (303, 503) requesting the UE (210) to establish a connection for at least one idle Slice (1 10) of the plurality of Slices.

17. The CN system (230) of claim 16, wherein the at least one CN instance (231 , 232) is configured: to infer at least one base station (220) to be used for paging the UE (210); and to gather information, in particular from the ICA-CN (235), by which a number of candidate base stations (106a, 106b, 106c) used for the paging (109a, 109b) can be reduced, in particular information of CN states, serving base stations, connection histories and/or tracking area lists of the plurality of Slices.

18. The CN system (230) of claim 16, wherein the at least one CN instance (231 , 232) is configured: to transmit the connection request (303, 503) based on paging-free procedures via the at least one active Slice (120) to the UE (210) based on priority levels of the plurality of Slices.

19. The CN system (230) of one of claims 16 to 18, wherein the at least one CN instance (231 , 232) is configured: to request the UE (210) to establish the connection for the at least one idle Slice (1 10) based on paging-free non Random Access Channel (RACH) procedures (ALT2) when connecting the at least one idle Slice (1 10) to a same base station or hypercell and/or when location information of the UE (210) is known.

20. The CN system (230) of one of claims 16 to 19, wherein the at least one CN instance (231 , 232) is configured: to request the UE (210) to establish the connection for the at least one idle Slice (1 10) based on paging-free Random Access Channel (RACH) procedures (ALT1 ) when connecting the at least one idle Slice (1 10) to a same base station or to neighboring base stations.

21 . A method (1900) for enabling connection establishment for an idle Slice (1 10) of a User Equipment (UE) (210), the method comprising: receiving (1901 ) an activation command for at least one idle Slice (1 10) of a plurality of Slices, wherein the activation command orders a connection establishment for the at least one idle Slice (1 10); and setting (1902) the UE (210) to an active state for enabling the connection establishment for the at least one idle Slice (1 10).

22. A communication system (200, 300, 500, 700, 800, 900, 1000, 1200, 1400), comprising: a user equipment (210) according to one of claims 1 to 10; a Radio Access Network (RAN) Entity (220) according to one of claims 1 1 to 15; and a CN system (230) according to one of claims 16 to 20.