WO2019081005A1

WO2019081005A1 - Assuring a homogeneous e2e slice sla using flexible slice segments

Info

Publication number: WO2019081005A1
Application number: PCT/EP2017/077257
Authority: WO
Inventors: Emmanouil Pateromichelakis; Konstantinos Samdanis; Xueli AN; Chenghui Peng
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2017-10-25
Filing date: 2017-10-25
Publication date: 2019-05-02

Abstract

The present invention relates to a cross‐domain slice management entity (NSMF) for enabling a service provision (SLA) across an end‐to‐end (E2E) network slice. The cross‐domain slice management entity is configured to create slice segments for the E2E network slice based on a slice request and on domain status information from a domain ((R) AN, TN, CN) within the E2E network slice, to configure the slice segments such that all slice segments have an identical service provision, to map the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information, and to send the domain specific mapping information to respective domain specific management entities (AN‐NSSMF, TN ‐ NSSMF, CN‐NSSMF) using dedicated interfaces.

Description

TITLE

Assuring a homogeneous E2E slice SLA using flexible slice segments. TECHNICAL FIELD

The present invention relates to the field of wireless communications, and more particularly to the field of network slicing.

BACKGROUND

Network Slicing is a key enabler for fifth generation (5G) which allows new business value creation opportunities by accommodating verticals, application providers and other third parties. In particular, it enables a concurrent deployment of multiple logical, self-contained networks on a common physical infrastructure with diverse business demands. The technical report 3GPP TR 23.501 (Release 15), entitled: "System architecture for the 5G system", defines a network slice as a complete logical network comprising a set of Network Functions (NFs) and corresponding resources, which are necessary to provide certain network capabilities and network characteristics. A network slice may include both a Radio Access Network (RAN) or Access Network (AN), a Transport Network (TN) and a Core Network (CN). Network slicing accommodates distinct Service Level Agreements (SLAs) and supports a fully customized network resource provision translated into different End-to-End (E2E) Key Performance Indicators (KPIs), thereby transforming the static "one size fits all" paradigm to a network of capabilities in which logical networks are created on- demand with the appropriate isolation, and to a resource optimization in order to serve a particular service type. A Network Slice Instance (NSI), which represents the realization of a network slice for a particular service, may be defined as a set of NFs and resources for these NFs arranged and configured, thereby forming a complete logical network to meet certain network characteristics.

5G mobile networks are envisioned to be heterogeneous by integrating all previous RAN generation and, at the same time, introducing new technologies such as New Radio (NR) and millimeter wave (mmWave). 5G offers a variety of service assurance even when the bandwidth requirements and selected backhaul paths are the same, due to different radio conditions (i.e., cell center/cell edge, weather conditions), access technologies (e.g., LTE, mmWave, WiFi) which determine the reliability and may use different backhaul paths, backhaul technologies (e.g., base station (BS) connected via optical or microwave) connected via different backhaul topologies, and connectivity options (e.g., dual connectivity, Coordinated Multipoint (CoMP) or conventional single path connectivity, Cloud- RAN (C-RAN) connectivity). A network slice may be requested to serve a large geographic area (e.g., Munich). In such a case, it may search among different types of equipment and technology across the RAN, CN and TN (e.g., BackHaul/FrontHaul (BH/FH)), with diverse characteristics. However, to ensure a homogeneous service provision (e.g., SLA) across an allocated geographical area while also considering user and network context information under a dynamic environment is a challenging problem whose solution is not straightforward, in particular due to inter-node interference, user mobility (e.g., low and high mobility), user density, load distribution, air interface and spectrum considerations (e.g., different Acoustic Induced Vibrations (AIVs)). In addition, it is not obvious which resources to allocate and/or combine together in order to guarantee a stable desired SLA.

Among the standard solutions to assure a unified-homogeneous service provision, a first one consists in overprovisioning the resources. In the worst-case scenario, this would lead to allocate resources in the whole area. However, this solution has the disadvantage to be sub-optimal since more resources are then needed, thereby resulting in wasted costs. A second one consists in quantifying the E2E SLA based on the perceived user experience and allocating the appropriate resource to ensure a stable SLA. However, this solution has the disadvantage to require multiple domains to be synchronized and to also require real-time information (per ms) to be acquired for the E2E scheduling decisions. SUMMARY

It is therefore an object to improve of the present invention to ensure a unified-homogeneous service provision across an E2E network slice within a geographical area, which is subject to a fluctuating performance due to multiple dynamically changing factors across a heterogeneous set of wireless and backhaul technologies and technology domains.

The object is achieved by the features of the independent claims. Further embodiments of the invention are apparent from the dependent claims, the description and the drawings.

According to a first aspect, the invention relates to a cross-domain slice management entity (NSMF) for enabling a service provision (SLA) across an end-to-end (E2E) network slice. The cross-domain slice management entity is configured to create slice segments for the E2E network slice based on a slice request and on domain status information from a domain ((R) AN, TN, CN) within the E2E network slice, to configure the slice segments such that all slice segments have an identical service provision, to map the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information, and to send the domain specific mapping information to respective domain specific management entities (AN-NSSMF, TN- NSSMF, CN-NSSMF) using dedicated interfaces.

Thereby, the above-mentioned problem may be solved by creating slice segments for the E2E network slice covering a geographical area, which are configured to have each an identical service provision (e.g., an equal SLA/QoS). The slice segments may be defined as a group of slice resources with equal service provision (SLA/QoS). In particular, a slice segment may be defined as a set of network functions (e.g., RAN-FH/BH-CN) and resources for these network functions that belong to a network slice and are arranged and configured within the specified geographical area in order to provide a controlled service provision (e.g., SLA). Using slice segments allows to simplify the problem by dividing it into smaller E2E instances with nearly-identical service provision (but not lower than the desired service provision), based on the radio/propagation conditions, the BH/FH resource availability and the CN resource utilization. The benefits of the proposed solution may be the provision of an equal service (e.g., QoS/SLA) over an entire geographical area with no over- provisioning of resources, and the fact that a slice segment defines a way of SLA treatment and thereby allows to avoid any calculation per user treatment to ensure the desired QoS.

According to an implementation form of the first aspect, the slice request comprises at least one of slice service provision requirement and slice coverage requirement, and the domain status information comprises at least one of statistics on a status and/or load of the domains, statistics on a traffic distribution, density and mobility patterns of users per slice area, user location

information, a resource situation and resource availability. According to a further implementation form of the first aspect, the domain specific mapping information comprises slice segment information containing a slice segment identifier for each slice segment, and configuration information containing radio resource management (RRM) policies for users in an area covered by a slice segment. According to a further implementation form of the first aspect, the cross-domain slice management entity is configured to send configuration parameters based on a user distribution to a RAN domain management entity (AN-NSSMF). According to a further implementation form of the first aspect, the domain specific mapping information sent to the respective domain specific management entities is RAN domain mapping information, which is sent as a slice segment-to-RAN mapping message to the RAN domain management entity (AN-NSSMF), and/or TN domain mapping information, which is sent as a slice segment-to-TN mapping message to a TN domain management entity (TN-NSSMF), and/or CN domain mapping information, which is sent as a slice segment-to-CN mapping message to a CN domain management entity (CN-NSSM F).

According to a further implementation form of the first aspect, the TN domain mapping information is sent from a mobile cross-domain slice management entity (e.g., NSMF) directly and/or via a fixed cross-domain slice management entity or via another operating entity (e.g., an entity of a same level as the slice management entity).

The above object is also solved in accordance with a second aspect.

According to the second aspect, the invention relates to a domain specific management entity (AN- NSSMF, TN-NSSMF, CN-NSSMF) as specified in the first aspect and/or any one of the

implementation forms of the first aspect. The domain specific management entity is configured to match user distributions to configured slice segments, to store radio resource management (RRM) policies for users in an area covered by a slice segment, and to send slice segment information comprising the RRM policies to a corresponding domain (AN, TN, CN). The above object is also solved in accordance with a third aspect.

According to the third aspect, the invention relates to a domain ((R) AN, TN, CN), which is configured to obtain, from a corresponding domain specific management entity as claimed in the second aspect, slice segment information comprising RRM policies, and to apply, at a node of the domain, a RRM policy amongst the RRM policies. According to an implementation form of the third aspect, the node of the domain is configured to trigger a change in the applied RRM policy in order to support the configured slice segments.

According to a further implementation form of the third aspect, the node of the domain triggers the change in the applied RRM policy by sending a message (RRM_CoMP_Policy_Trigger message) to the corresponding domain specific management entity. The above object is also solved in accordance with a fourth aspect.

According to the fourth aspect, the invention relates to a method for enabling a service provision (SLA) across an end-to-end (E2E) network slice. The method is performed at a cross-domain slice management entity and comprises the step of creating slice segments for the E2E network slice based on a slice request and on domain status information from a domain ((R) AN, TN, CN) within the E2E network slice, the step of configuring the slice segments such that all slice segments have an identical service provision, the step of mapping the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information, and the step of sending the domain specific mapping information to respective domain specific management entities (AN-NSSMF, TN-NSSMF, CN-NSSMF) using dedicated interfaces. The above object is also solved in accordance with a fifth aspect.

According to the fifth aspect, the invention relates to a method, which is performed at a domain specific management entity and comprises the step of matching user distributions to configured slice segments, the step of storing radio resource management (RRM) policies for users in an area covered by a slice segment, and the step of sending slice segment information comprising the RRM policies to a corresponding domain (AN, TN, CN).

The above object is also solved in accordance with a sixth aspect.

According to the sixth aspect, the invention relates to a method, which is performed at a domain and comprises the step of obtaining, from a corresponding domain specific management entity, slice segment information comprising RRM policies, and the step of applying, at a node of the domain, a RRM policy amongst the RRM policies.

The above object is also solved in accordance with a seventh aspect. According to the seventh aspect, the invention relates to a computer program product comprising a program code for performing a method according to any one of fourth, fifth and sixth aspects when executed on a computer. Thereby, the method can be performed in an automatic and repeatable manner. The computer program can be performed by the above apparatuses.

More specifically, it should be noted that all the above apparatuses may be implemented based on a discrete hardware circuitry with discrete hardware components, integrated chips or

arrangements of chip modules, or based on a signal processing device or chip controlled by a software routine or program stored in a memory, written on a computer-readable medium or downloaded from a network such as the Internet.

It shall further be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.

These and other aspects of the invention will be apparent and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the invention will be explained in more detail with reference to the exemplary embodiments shown in the drawings, in which:

Fig. 1 shows an exemplary scenario of a slice segment creation based on a user location

distribution, according to an embodiment of the present invention;

Fig. 2 shows a first flow chart (2-A) illustrating an allocation of weight to nodes and a second flow chart (2-B) illustrating an adapted graph-based solution to find a number of maximal cliques covering an entire graph, according to an embodiment of the present invention;

Fig. 3 shows a message sequence chart (MSC) for slice instantiation and slice segment mapping per domain ((R) AN, TN, CN), according to an embodiment of the present invention;

Fig. 4 shows a schematic signaling chart illustrating a transmission of a TN domain mapping information from a mobile cross-domain slice management entity (NSMF) towards a TN domain management entity (TN-NSSMF) according to two options, according to an embodiment of the present invention; and Fig. 5 shows a message sequence chart (MSC) illustrating a RRM CoM P policy application at a RAN node, according to an embodiment of the present invention.

Identical reference signs are used for identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The gist of the present invention is to create and configure slice segments at a cross-domain slice management entity (or unit) in order to allocate an E2E network slice across RAN and/or TN and/or CN with equal area-KPIs.

Fig. 1 shows an exemplary scenario of a slice segment creation based on a user location distribution, according to an embodiment of the present invention.

The left side of the drawing shows a location distribution of users (e.g., User Equipment (UE) devices) in an area covered by a slice x. A slice management entity (e.g., Network Slice

Management Function (NSMF) or Network Slice Su bnet Management Function (NSSMF) in 3GPP SA5 terminology) receives, from this left side, RAN/UE/BH traffic and resource context information and decides, based on it, to create and configure slice segments of the slice x. The right part of the drawing shows the clustering of the geographical area covered by the slice x into four slice segments or clusters (numbered from 1 to 4) with different configuration policies. It shall be noted that, in the case of having different distribution options (e.g., low load, medium load, high load), the slice management entity may create all possible combinations of slice segments and configurations (e.g., for low, medium, high load), and the Base Stations (BSs) may then apply one of the configurations based on the real-time information about the connected users. It shall be also noted that, for different slices, different slice segments and configurations may be defined based on the target KPI/SLA.

The criteria for the slice segment creation and the slice segment dimensioning as areas in which the involved entities (e.g., UEs, BSs) are expected to have similar RAN/UE/BH characteristics may be identified by some potential SLA parameters and QoS-related measurements, and also by the expected/estimated location distribution of users in a geographical area covered by a slice. For example, those criteria may comprise a Signal-to-lnterference-plus-Noise Ratio (SINR) (path loss and interference), a spectral efficiency, an uplink/downlink load at a BS, an access channel delay (connectivity density), a throughput (difference between BH and radio), a delay (re-transmission probability (for radio), processing delay/queuing (e.g., for router, switch), probe or in traffic (for E2E)), and reliability (percentage of traffic successfully delivered).

It shall be noted that the expected/estimated location distribution of the users may be known from the actual/expected positioning of users in a geographical area based on mobility patterns and/or historical data/statistics on the distribution of users in this area and/or at worst an assumption of a uniform distribution over the slice coverage area.

The configuration of the slice segments for the E2E network slice may be mainly based on parameters and user location distributions and/or patterns based on statistics, in order to ensure an equal area-QoS and/or SLA within each slice segment. A core part of the configuration is to define the parameters (e.g., size, coverage) of the slice segments in such a way that identical service provision (i.e., equal area-KPI) can be achieved per slice cluster (i.e., per slice segment). The criteria for the selection of the cluster parameterization, which is based on the given user location distribution, may, for example, comprise a location distribution of users per slice segment in an entire area and per BS area, BH constraints (e.g., ideal and/or non-ideal BH, type, topology, availability, dynamicity), a target KPI per slice, an estimated KPI achieved according to slice requirements, a user's estimated SIN (initial selection of serving BS by Reference Signal Received Power (RSRP) and/or Reference Signal Received Quality (RSRQ)), a spectral efficiency and/or a min- max throughput using SINR and min-max allocated bandwidth, a delay (e.g., probability of retransmissions (Automatic Repeat reQuest (ARQ), Hybrid ARQ (HARQ), probe, propagation latency, number of hops), a reliability (e.g., probability of successfully decoding X traffic at the BS-UE link in a frame), a connection density (number of connected devices per area), and Radio Resource Management (RRM) policies and the respective KPI gains achieved over these policies.

In more details, the slice segment creation, dimensioning and configuration may comprise creating a graph of users based on user distribution information and slice requirements, as presented in the following steps 1 to 7. In the first (1) step, the cross-domain slice management entity (e.g., NSMF in 3GPP) may collect and create a set of user distribution patterns for the given E2E network slice based on statistics and slice coverage requirements. For each user distribution, in the second (2) step, a graph of users may be created. The nodes or vertices may be the generated potential user coordinates (according to the user distribution) and the edges may show whether two users are initially served by the same BS and/or the same predefined group of BSs.

Then, in the third (3) step, a weight may be introduced to each node using, as a metric, an estimation of achieving the target KPI. To update the weights and ensure similar weights for all users (above the target KPI), a potential M policy may be further applied. As illustrated in the flow chart of Fig. 2-A, once all potential or "virtual" users have been listed according to a distribution (coverage, target KPI, demand) (step depicted as S2-1), for each node or vertex, an estimated KPI (eKPI) per user is calculated based on an expected location (taking into account a serving BS as the closest one, the other ones as interfering BS) (step depicted as S2-2). The estimated KPI (eKPI) is assessed with respect to the target KPI (step depicted as S2-3). If an estimated KPI (eKPI) is less than the target KPI, then, for each slice cluster, alternative KPIs (aKPIs) per given policy (e.g., Coordinated Multipoint (CoMP)) are calculated based on an expected location and expected gains from each policy (step depicted as S2-4). Amongst all alternative KPIs (aKPIs), the lowest KPI that is greater than the target KPI is selected as "agreed_KPI" and a weight of node is attributed to the "agreed_KPI" (step depicted as S2-5). If an estimated KPI (eKPI) is greater than the target KPI, a weight node is attributed to the estimated KPI (eKPI) (step depicted as S2-6).

In the fourth (4) step, an edge may be introduced between the users, taking into account the serving BS.

In the fifth (5) step, the graph (per user distribution and per slice) may be solved by partitioning nodes into slice clusters with equal area-KPI, which is the summation of weights of the

corresponding users (this occurs in order to balance the load between the slice clusters). Each slice cluster/segment will contain users with different RRM policies, but since their exact location is unknown, only the percentage of users corresponding to each policy will be used. So, the RAN can perform its own scheduling and the BH can be provisioned more efficiently. Finally, solving the graph leads to the provision of slice clusters/segments, different RRM policies to be applied, a range (min, max) of users per cluster, and a percentage of users per RRM policy. Indeed, the problem to be solved consists in finding a number of maximal cliques to cover the entire graph, wherein each maximal clique has the same intra-clique sum node weight, as depicted in the flow chart of Fig. 2-B through the steps S2-7 to S2-11. In step S2-7, all complete sub-graphs of the graph G(V,E) are listed and sorted, where V is the set of users and E is the set of edges between users for a given distribution. In step S2-8, the sum-node weights for all complete sub-graphs are calculated and stored. In step S2-9, all combinations of sub-graphs that include all nodes of the graph and do not have duplicate nodes are generated. In step S2-10, the minimum and maximum sum-weights for each combination of sub-graphs are calculated. In step S2-11, the combination of sub-graphs that has a minimum difference of sum-weights is selected and extracted. This is an adaptation of a modified version of a graph-based problem as disclosed in: Behrisch, M. and Taraz, A., "Efficiently covering complex networks with cliques of similar vertices", Theoretical Computer Science, Vol. 355, Issue 1, pp. 37-47, 2006.

In the sixth (6) step, the second, third, fourth and fifth steps may be iteratively performed for a next user distribution.

In the seventh (7) step, the involved domains ((R) AN, TN, CN) may be informed about the slice segment activation, the covered area and the slice cluster/segment parameters for the different user distributions.

Once the slice segments have been created, dimensioned and configured, the present invention proposes a slice segment mapping per domain for the E2E network slice covering a geographical area.

Using the 3GPP SA5 terminology, Fig. 3 shows a message sequence chart (MSC) for slice instantiation and slice segment mapping per domain ((R) AN, TN, CN), according to an embodiment of the present invention. In step S3-1, the cross-domain slice management entity (NSMF) receives a slice request, for example, from a Communication Service Management Function (CSMF) entity or an application or a third party or a vertical. The slice request may comprise, in a non-limitative manner, at least one of slice service provision requirement and slice coverage requirement. In step S3-2, the cross-domain slice management entity (NSMF) also receives periodically domain specific status information from respective domains ((R) AN, TN, CN) through respective domain specific management entities ((R) AN domain management entity, TN domain management entity and CN domain management entity). As depicted, those domain specific management entities may be, for example, domain specific Network Slice Subnet Management Function (i.e., (R) AN-NSSMF, TN-NSSMF, CN-NSSMF) entities. The domain specific status information may comprise, in a non- limitative manner, at least one of statistics on a status and/or load of the domains, statistics on a traffic distribution, density and mobility patterns of users per slice area, user location information, a resource situation and resource availability. In step S3-3, the cross-domain slice management entity (NSMF) performs the steps 1 to 6 as above- mentioned for the slice segment creation, dimensioning and configuration.

In step S3-4, the cross-domain slice management entity (NSMF) generates domain specific mapping information by mapping the configured slice segments to each domain across the E2E network slice amongst the (R) AN, TN and CN domains, and sends that domain specific mapping information to the respective domain specific management entities, namely (R) AN-NSSMF, TN-NSSMF and CN- NSSMF entities as depicted, using dedicated interfaces. The domain specific mapping information may comprise slice segment information containing a slice identifier (denoted as Slice ID) (i.e., an E2E network slice identifier), a slice segment identifier (denoted as Segment ID) for each slice segment, and configuration information containing Radio Resource Management (RRM) policies for users in an area covered by a slice segment. From a signaling standpoint, the RAN domain mapping information may be sent as a slice segment-to-RAN mapping message to the RAN domain management entity (AN-NSSMF), the TN domain mapping information may be sent as a slice segment-to-TN mapping message to the TN domain management entity (TN-NSSMF), and the CN domain mapping information may be sent as a slice segment-to-CN mapping message to the CN domain management entity (CN-NSSM F).

In step S3-5, the cross-domain slice management entity (NSMF) sends configuration parameters based on a user distribution to the RAN domain management entity (AN-NSSMF). From a signaling standpoint, the configuration parameters may be sent as a Segment_Distr_Params message and comprise the following parameters: service identifiers (IDs), distribution type, min-max number of users (e.g., UEs) to be supported, coverage, RRM policy parameters and percentage of users per RRM policy.

In step S3-6, each domain specific management entity (AN-NSSMF, TN-NSSMF, CN-NSSMF) matches the user distributions to the configured slice segments, stores the RRM policies for users in an area covered by a slice segment, and sends slice segment information comprising those RRM policies towards its corresponding domain (AN, TN, CN). Upon receiving the RRM policies (step not shown in Fig. 3), a RRM policy will be then applied at a node (e.g., BS) of the involved domain (e.g., AN). In step S3-7, the slice segment information may also be sent from the cross-domain slice management entity (NSMF) towards another entity of the same level, for example, another cross- domain slice management entity (NSMF) or any operating entity, in order to notify it about the expected load of the network in case of sharing RAN domain resources.

Referring to Fig. 4, it shall be noted that the TN domain mapping information may be sent from a mobile cross-domain slice management entity (e.g., mobile NSMF) towards the TN domain management entity (e.g., TN-NSSMF) according to two options, namely either directly as achieved in step S3-4 of Fig. 3 (option 1), or via a fixed cross-domain slice management entity (e.g., fixed NSMF) or another operating entity of the same level as the cross-domain slice management entity (option 2).

Fig. 5 shows a message sequence chart (MSC) illustrating a RRM CoMP policy application at a RAN node, according to an embodiment of the present invention.

In conjunction with the step S3-6 of Fig. 3, the (R)AN domain management entity (e.g., AN-NSSMF) sends, in step S5-1, slice segment information, which comprises RRM policy information, resources and coverage, towards all RAN nodes (e.g., Nodes B, eNodes B, gNBs). Upon receiving all the necessary slice segment information, the RAN nodes can then apply a certain RRM policy such as a CoMP policy, for example. In this embodiment, it is assumed that a radio resource control (RRC) connection has been esta blished and a user (e.g., UE device) is attached to a network slice, resides in a cluster/segment area and is moving towards a cell supporting the network slice.

In step S5-2, the user (e.g., UE device) sends radio measurements towards a serving RAN node (e.g., serving gNB) of the cell.

Based on the new/modified slice segment information and assuming that the user moves towards a geographical area where this slice segment applies (e.g. cell edge), the serving RAN node (e.g., serving gNB) triggers, in step S5-3, a change in the applied RRM policy, in order to support the new/modified configured slice segments, by sending a dedicated message towards the (R)AN domain management entity (e.g., AN-NSSMF). In our example, the RRM policy is to enable

Coordinated Multipoint Tx/Rx (CoMP), so that the dedicated message is sent as a

RRM_CoMP_Policy_Trigger message, which may comprise information about UE ID, slice segment ID, target gNB ID and CoMP scheme. In step S5-4, the (R)AN domain management entity (e.g., AN-NSSMF) notifies the other involved RAN node (e.g., gNB) about the CoMP policy initiation using a slice segment information message.

In step S5-5, the other involved RAN node (e.g., gNB) sends an acknowledgment message towards the serving RAN node (e.g., serving gNB).

In step S5-6, the user (e.g., UE device) sends radio measurements towards both RAN nodes (e.g., serving gNB, gNB). In step S5-7, the serving RAN node (e.g., serving gNB) sends information about UE channel state information (CSI), data, etc. towards the other involved RAN node.

Afterwards, in step S5-8, the serving RAN node and the other involved RAN node serve the user (e.g., UE device) jointly in order to enhance his KPI.

In summary, the present invention relates to a cross-domain slice management entity (NSMF) for enabling a service provision (SLA) across an end-to-end (E2E) network slice. The cross-domain slice management entity is configured to create slice segments for the E2E network slice based on a slice request and on domain status information from a domain ((R) AN, TN, CN) within the E2E network slice, to configure the slice segments such that all slice segments have an identical service provision, to map the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information, and to send the domain specific mapping information to respective domain specific management entities (AN-NSSMF, TN- NSSMF, CN-NSSMF) using dedicated interfaces. Thereby, the present invention can ensure a unified-homogeneous service provision across an E2E network slice within a geographical area, which is subject to a fluctuating performance due to multiple dynamically changing factors across a heterogeneous set of wireless and BH technologies and of technology domains. While the present invention has been illustrated and described in detail respectively in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. From reading the present disclosure, other modifications will be apparent to a person skilled in the art. Such modifications may involve other features, which are already known in the art and may be used instead of or in addition to features already described herein.

The invention has been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Although the present invention has been described with reference to specific features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded simply as an illustration of the invention as defined by the appended claims, and are contemplated to cover any and all modifications, variations,

combinations or equivalents that fall within the scope of the present invention.

Claims

1. A cross-domain slice management entity (NSMF) for enabling a service provision (SLA) across an end-to-end (E2E) network slice, the cross-domain slice management entity being configured to: create slice segments for the E2E network slice based on a slice request and on domain status information from a domain (( ) AN, TN, CN) within the E2E network slice; configure the slice segments such that all slice segments have an identical service provision; map the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information; and

- send the domain specific mapping information to respective domain specific management entities (AN-NSSMF, TN-NSSMF, CN-NSSMF) using dedicated interfaces.

2. The cross-domain slice management entity of claim 1, wherein:

- the slice request comprises at least one of slice service provision requirement and slice coverage requirement; and

- the domain status information comprises at least one of statistics on a status and/or load of the domains, statistics on a traffic distribution, density and mobility patterns of users per slice area, user location information, a resource situation and resource availability.

3. The cross-domain slice management entity of claim 1 or 2, wherein:

- the domain specific mapping information comprises slice segment information containing a slice segment identifier for each slice segment, and configuration information containing radio resource management (RRM) policies.

4. The cross-domain slice management entity of any one of claims 1 to 3, which is configured to:

send configuration parameters based on a user distribution to a RAN domain management entity (AN-NSSMF).

5. The cross-domain slice management entity of any one of claims 1 to 4, wherein the domain specific mapping information sent to the respective domain specific management entities is:

- RAN domain mapping information, which is sent as a slice segment-to-RAN mapping message to the RAN domain management entity (AN-NSSMF); and/or - TN domain mapping information, which is sent as a slice segment-to-TN mapping message to a TN domain management entity (TN-NSSM F); and/or

- CN domain mapping information, which is sent as a slice segment-to-CN mapping message to a CN domain management entity (CN-NSSM F).

6. The cross-domain slice management entity of claim 5, wherein:

- the TN domain mapping information is sent from a mobile cross-domain slice management entity directly and/or via a fixed cross-domain slice management entity or via another operating entity.

7. A domain specific management entity (AN-NSSMF, TN-NSSMF, CN-NSSMF) as specified in any one of claims 1 to 6, which is configured to: match user distributions to configured slice segments;

store radio resource management ( M) policies; and

send slice segment information comprising the RRM policies to a corresponding domain (AN, TN, CN).

8. A domain ((R) AN, TN, CN), which is configured to: obtain, from a corresponding domain specific management entity as claimed in claim 7, slice segment information comprising RRM policies; and

- apply, at a node of the domain, a RRM policy amongst the RRM policies.

9. The domain of claim 8, wherein the node of the domain is configured to:

- trigger a change in the applied RRM policy in order to support the configured slice segments.

10. The domain of claim 9, wherein the node of the domain triggers the change in the applied RRM policy by sending a message (RRM_CoMP_Policy_Trigger message) to the corresponding domain specific management entity.

11. A method for enabling a service provision (SLA) across an end-to-end (E2E) network slice, the method being performed at a cross-domain slice management entity and comprising:

creating slice segments for the E2E network slice based on a slice request and on domain status information from a domain ((R) AN, TN, CN) within the E2E network slice; configuring the slice segments such that all slice segments have an identical service provision; mapping the configured slice segments to each domain across the E2E network slice amongst at least a radio access network (RAN) domain, a transport network (TN) domain and a core network (CN) domain, as to obtain domain specific mapping information; and sending the domain specific mapping information to respective domain specific management entities (AN-NSSMF, TN-NSSMF, CN-NSSMF) using dedicated interfaces.

12. A method being performed at a domain specific management entity and comprising: matching user distributions to configured slice segments;

storing radio resource management (RRM) policies; and

sending slice segment information comprising the RRM policies to a corresponding domain (AN, TN, CN).

13. A method being performed at a domain and comprising: obtaining, from a corresponding domain specific management entity, slice segment information comprising RRM policies; and

applying, at a node of the domain, a RRM policy amongst the RRM policies.

14. A computer program comprising:

a program code for performing the method according to any one of claims 11 to 13 when executed on a computer.