WO2022122126A1

WO2022122126A1 - Changing a coverage area of a network slice

Info

Publication number: WO2022122126A1
Application number: PCT/EP2020/085089
Authority: WO
Inventors: Patrick Maguire
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2020-12-08
Filing date: 2020-12-08
Publication date: 2022-06-16

Abstract

In one aspect, a method performed by a network node for changing a coverage area of a network slice in a communications network is provided. The method comprises obtaining performance information for one or more boundary regions defining at least part of a boundary of the coverage area, in which the performance information is indicative of demand for one or more services provided by the network slice. The method further comprises changing the boundary of the coverage area based on the performance information.

Description

CHANGING A COVERAGE AREA OF A NETWORK SLICE

Technical Field

Examples of the present disclosure relate to changing a coverage area of a network slice in a communications network.

Background

With the advent of Fifth Generation (5G) networks, network operators are tasked with providing a more diverse range of services for a broader spectrum of device types. Network slices are being proposed as a way to increase the range of services provided by the network whilst minimising the risk of networks being over-dimensioned. In this approach, aspects of software defined networking (SDN) and network function virtualisation (NFV) may be used to create logical networks (e.g. virtual networks) that are configured for a particular use-case (e.g. a particular business purpose) or enduser (see, for example, the 5G White Paper issued by the Next Generation Mobile Networks, NGMN, alliance, February 2015, V1.0). A network slice may be described by a machine-readable blueprint (e.g. a slice template), which describes the type of resources or components that the slice is composed of and how those resources or components are interconnected and configured to provide one or more services.

A network slice may have a particular coverage area, defining a region in which terminals or devices can access the network slice. Thus, for example, the coverage area for a network slice may comprise one or more cells served by radio access nodes in a radio access network. Wireless devices served by those cells may thus have access to services that are available in the network slice.

Summary

As network coverage is a finite resource, there is a balance to be struck between associating network slices with sufficiently large coverage areas that the provision of network services is not overly restricted, whilst still using network resources efficiently. In particular, if the coverage of a network slice includes areas in which demand for the services provided by the network slice is low or absent, then including those areas in the coverage area for the network slice risks wasting network resources. For example, paging may be performed on a network slice level, which can result in paging attempts being made to parts of the coverage area in which wireless devices are rarely located. One aspect of the present disclosure provides a method performed by a network node for changing a coverage area of a network slice in a communications network. The method comprises obtaining performance information for one or more boundary regions defining at least part of a boundary of the coverage area, the performance information being indicative of demand for one or more services provided by the network slice. The method further comprises changing the boundary of the coverage area based on the performance information

In a further aspect, the present disclosure provides a network node configured to perform the aforementioned method. The network node may be, for example, a physical network node (e.g. an apparatus) or a virtual network node (e.g. a virtual network function).

A still further aspect of the present disclosure provides a network node for changing a coverage area of a networks slice. The network node comprises a processor and a memory, in which the memory contains instructions executable by the processor such that the network node is operable to obtain performance information for one or more boundary regions defining at least part of a boundary of the coverage area, in which the performance information is indicative of demand for one or more services provided by the network slice. The network node is further operable to change the boundary of the coverage area based on the performance information.

Brief description of the drawings

For a better understanding of examples of the present disclosure, and to show more clearly how the examples may be carried into effect, reference will now be made, by way of example only, to the following drawings in which:

Figure 1 illustrates a communications network according to an example of the disclosure;

Figures 2-4 illustrate a part of a network according to examples of the disclosure;

Figure 5 illustrates a system according to an example of the disclosure;

Figure 6 is a flowchart of an example of a method of changing a coverage area of a network slice; and Figure 7 is a schematic illustration of an example of a network node for changing a coverage area of a network slice.

Detailed description

The following sets forth specific details, such as particular embodiments or examples for purposes of explanation and not limitation. It will be appreciated by one skilled in the art that other examples may be employed apart from these specific details. In some instances, detailed descriptions of well-known methods, nodes, interfaces, circuits, and devices are omitted so as not obscure the description with unnecessary detail. Those skilled in the art will appreciate that the functions described may be implemented in one or more nodes using hardware circuitry (e.g., analogue and/or discrete logic gates interconnected to perform a specialized function, ASICs, PLAs, etc.) and/or using software programs and data in conjunction with one or more digital microprocessors or general purpose computers. Nodes that communicate using the air interface also have suitable radio communications circuitry. Moreover, where appropriate the technology can additionally be considered to be embodied entirely within any form of computer-readable memory, such as solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein.

Figure 1 shows an example of a communications network 100 according to examples of the disclosure.

The communications network 100 comprises a radio access network (RAN) 102. The RAN 102 may implement any suitable wireless communications protocol or technology, such as Global System for Mobile communication (GSM), Wide Code-Division Multiple Access (WCDMA), Long Term Evolution (LTE), New Radio (NR), WiFi, WiMAX, or Bluetooth wireless technologies. In one particular example, the network 100 forms part of a cellular telecommunications network, such as the type developed by the 3^rd Generation Partnership Project (3GPP).

The RAN 102 comprises a first RAN node 104a and a second RAN node 104b (104 collectively). The RAN nodes 104 provides access to a core network 106 for one or more wireless devices (not illustrated) served by the RAN nodes 104. The geographical extent over which a RAN node is configured to provide connectivity to the network 100 is referred to as its coverage area. Each of the RAN nodes 104 may thus be configured to communicate with wireless devices within their coverage areas. The RAN nodes 104 may be, for example, base stations such as, for example, Node Bs, evolved Node Bs (eNBs) or New Radio (NR) NodeBs (gNBs).

The core network 106 comprises a plurality of core network nodes 108. As illustrated, the first RAN node 104a is connected to a first core network node 108a, whereas the second RAN node 104b is connected to a second core network node 108b and a third core network node 108c. The RAN nodes 104 may be connected to their respective core network nodes 108 by a backhaul network, for example.

Three network slices, NS1 110, NS2 112 and NS3 114, are implemented in the communications network 100. In this context, a network slice is a logical partition (e.g. a virtual network) in the communications network 100. A network slice may thus comprise a portion of available resources in the communications network 100.

Three service instances, Service A 118a, Service B 118b and Service C 118c (collectively 118) are deployed in the network 100. In particular, Service A 118a is only deployed in NS1 110, whereas Service B 118b is deployed in both NS1 110 and NS2 112. Service C 118c is deployed in NS3 114. Although three service instances are deployed in the network 100 in this example, the skilled person will appreciate that, in general, one or more services may be deployed in the network 100.

Each of the network slices 110-114 has a respective coverage area in which services deployed in the network slice 110-114 are available. The coverage area of a network slice is determined by the RAN nodes in the network slice. The coverage area of a network slice is thus the combined area in which RAN nodes in the network slice are configured to provide connectivity to the network (e.g. the combined area served by RAN nodes in the network slice).

In the illustrated example, NS1 110 comprises the first RAN node 104a, which means that the coverage area of NS1 110 comprises the geographical region in which the first RAN node 104a is configured to provide to the network 100 (e.g. the coverage area of the first RAN node 104a). More specifically, in this example, the first RAN node 104a is the only access node in NS1 110, which means that the coverage area of NS1 110 is the coverage area of the first RAN node 104a.

Service A 118a and Service B 118, which are both deployed in NS1 110, are thus available to wireless devices served by the first RAN node 104a. As Service A 118a is only deployed in NS1 110 (e.g. it is not deployed in either of NS2 112 or NS3 114), it is only available to wireless devices in the coverage area of the first RAN node 104a.

Similarly, for NS2 112 and NS3 114, the second RAN node 104b is the only access node in these network slices, which means the coverage areas of NS2 112 and NS3 114 are the coverage area of the second RAN node 104b. Services B and C 118b, 118c are deployed in NS2 112 and NS3 114 respectively, which means that both of these services are available to wireless devices served by the second RAN node 104b.

However, as noted above, Service A 118a is only deployed in NS1 110, and the coverage area of NS1 110 only extends to the coverage area of the first RAN node 104a, which means that Service A 118a is only available to wireless devices served by the first RAN node 104a. This means that a device moving from the coverage area of the first RAN node 104a to, for example, the coverage area of the second RAN node 104b, may lose access to Service A 118a. Similarly, Service C 118c is only deployed in NS3 114, which means that a wireless device leaving the coverage area of the second RAN node 104b may lose access to Service C 118c. As well as risking service disruption for moving devices, this means that Services A 118a and C 118b may be underutilised, as there may be demand for those services outside of the coverage areas in which they are provided.

Aspects of the disclosure seek to address these and other problems by providing methods and network nodes for changing a coverage area of a network slice.

In one aspect, a method performed by a network node for changing a coverage area of a network slice is provided. The method comprises obtaining performance information for one or more boundary regions defining at least part of a boundary of the coverage area, in which the performance information is indicative of demand for one or more services provided by the network slice. The method further comprises changing the boundary of the coverage area based on the performance information. By adapting the coverage area based on information indicative of demand for one or more services, the present disclosure provides a method by which the geographical area over which services are made available can be adapted according to demand. If, for example, performance information indicates that there is little or no demand for a service in a part of the coverage area (e.g. a subregion of the coverage area), then the coverage area may be changed to exclude that part. This may, for example, reduce the incidence of paging attempts to areas in which wireless devices are rarely located, thereby preventing network resources from being wasted. Adapting the coverage area of a network slice in this manner thus improves network resource usage efficiency, whilst maintaining or even improving access to services where there is sufficient demand.

Two examples are described in more detail in respect of Figures 2-4. In these examples, the method is implemented in a cellular communications network, in which network coverage is defined in terms of one or more Tracking Areas (TAs), in which each TA comprises one or more cells. In these examples, the finest granularity of service area restriction is a single TA, which means that the minimal coverage of any network slice in the network is one TA.

Figure 2 illustrates a part of a communications network. The communications network may the communications network 100 described above in respect of Figure 1 , for example.

The communications network includes a plurality of cells (not numbered), which are represented by hatched ellipses in Figure 2. The cells are served by respective RAN nodes (not illustrated). The cells are divided into TAs, forming the eight TAs 202a, 202b,... 202g, 204 shown. Of these, seven TAs 202a, 202b,... 202g (202 collectively) form the coverage area 200 of a network slice. The remaining TA, neighbouring TA 204, is not in the network slice.

Of the seven TAs 202 in the coverage area 200, six of the TAs (TAs 202a-202f) are boundary or border TAs, forming part of the boundary (e.g. the outer extent) of the coverage area 200 of the network slice. In this context, a boundary TA may be any TA which is adjacent to or overlaps with a TA that is not in the same network slice. For example, a TA may be a boundary TA for a network slice if it includes at least one boundary cell, in which a boundary cell is a cell having at least one cell in its neighbour cell list that is in a different network slice.

In Figure 2, TA 202d and TA 202c are adjacent to the neighbouring TA 204, which is not in the same network slice. TAs 202d and 202c are thus boundary TAs, since they form part of the edge or boundary of the coverage area 200 of the network slice. In general, a boundary TA may be any TA in a network slice that is adjacent to or overlaps with a TA that does not form part of the same network slice. Thus, a TA may be a boundary TA if it has at least one neighbouring TA that is not in the same network slice. Two TAs may be neighbouring (e.g. considered neighbours) if, for example, handover of a wireless device from a cell in one of the TAs to another cell in the other of the two TAs is possible.

Accordingly, TAs 202a, 202b, 202e-202f are also boundary TAs because they are adjacent to or overlap with TAs that are not in the same network slice (not illustrated).

In contrast, TA 202g is surrounded by other TAs 202a-202f from the same network slice, and is thus not adjacent to or overlapping with any TAs that are not in the same network slice. Therefore, TA 202g is not a boundary TA in Figure 2.

As noted above, the coverage area of a network slice may be changed by obtaining performance information for one or more boundary regions of the coverage area and changing the boundary of the coverage area based on the performance region.

In a first example, the coverage area 200 of the network slice is increased based on performance information for the TA 202d. In particular, a network node (not illustrated) obtains performance information for the TA 202d, which comprises a number of failed handovers from TA 202d to TA 204. For example, a failed handover may be an attempt by a mobile device to handover from a cell in TA 202d to a cell in TA 204, but the handover is not successful, which may be because the mobile device is not authorized to connect to a cell in TA 204 (for example, the mobile device is only authorized to access cells in the network slice 200, and/or the mobile device is not authorized to access a different network slice currently provided by TA 204). The network node compares the number of failed handovers to a minimum threshold and determines that the number of failures exceeds this minimum threshold. Based on this determination, the network node determines that there is sufficient demand for one or more services provided by the network slice in the TA 204 and adds the neighbouring TA 204 to the coverage area 200 of the network slice.

The resulting updated coverage area 200 is shown in Figure 3. In comparison with Figure 2, the coverage area 200 has been expanded to include the additional TA 204. In this first example, the network node further updates which of the TAs 202, 204 in the (updated) coverage area 200 are determined to be boundary TAs. In particular, the newly added TA 204 is also determined to be a boundary TA since it is adjacent to or overlapping with one or more TAs not in the same network slice (not illustrated).

In a second example, the coverage area 200 of the network slice as shown in Figure 2 is decreased based on performance information for the boundary TA 202c. In particular, a network node (not illustrated) obtains performance information for the boundary TA 202c. The performance information comprises a number of packet data unit (PDU) sessions provided to one or more wireless devices served by cells in the TA 202c in a specified time period. A PDU session provides connectivity between applications on a UE and a data network (DN) such as the Internet or private corporate networks. The network node compares the number of PDU sessions to a minimum threshold and determines that the number of PDU sessions fails to meet this minimum threshold. Based on this determination, the network node determines that there is insufficient demand for one or more services provided by the network slice in the TA 202c and removes the TA 202c from the coverage area 200 of the network slice.

The resulting updated coverage area 200 is shown in Figure 4. In comparison with Figure 2, the boundary of the coverage area 200 has changed due to the removal of TA 202c from the coverage area 200. The network node further updates which of the TAs 202a, 202b, 202d-202g in the coverage area 200 are determined to be boundary TAs. In particular, the network node determines that the central TA 202g is now adjacent to a TA that is not in the same network slice (TA 202c), and is therefore now a boundary TA. Exemplary methods for determining whether a TA is a boundary TA are described in more detail below.

Figure 5 shows a system 500 according to an example of the disclosure. The system 500 comprises a RAN 502, which is configured to connect one or more devices (not illustrated) to a core network 504 in the system 500. The RAN 502 comprises one or more RAN nodes, such as the RAN nodes 104 described above in respect of Figure 1 , for example. The RAN nodes serve one or more cells. The cells are grouped into one or more TAs, such as the TAs 202, 204 described above in respect of Figure 2, for example. The RAN may implement any suitable wireless communications protocol or technology, such as Global System for Mobile communication (GSM), Wide Code-Division Multiple Access (WCDMA), Long Term Evolution (LTE), New Radio (NR), WiFi, WiMAX, or Bluetooth wireless technologies.

The core network 504 comprises one or more core network nodes, such as, for example, the core network nodes 108 described above in respect of Figure 1 . In examples in which the RAN 502 implements NR, the core network 504 may be a 5G core network.

The system further comprises a radio domain management node 506 and a core domain management node 508 for managing the RAN 502 and the core network 504 respectively. The system may thus, for example, comprise a first domain manager for managing the RAN 506 and a second domain manager for managing the core network 504. The radio domain management node 506 may be operable to perform fault, configuration, accounting, performance and/or security tasks for nodes in the RAN 502, for example. The core domain management node 508 may be operable to perform fault, configuration, accounting, performance and/or security tasks for nodes in the core network 505, for example.

In the illustrated example, the radio domain management node 506 and the core domain management node 508 are implemented as separate network functions (e.g. as separate domain managers). However, the skilled person will appreciate that the functionality of these nodes may alternatively be provided by a single node (e.g. implemented in a single network function), such as a network manager.

At least one network slice is implemented in the system 500. Each network slice implemented in the system 500 comprises at least part of the RAN 502 and the core network 504. The network slices are managed by a network slice orchestrator (e.g. a network slice orchestration and management node) 514, which is configured to manage the deployment of network slices in the system 500. The network slice orchestrator 514 may thus be operable to create network slices and reconfigure the network slices during their lifecycle.

In accordance with aspects of the present disclosure, the system 500 is operable to change a coverage area of a network slice deployed in the system 500. The network slice may be the network slice described above in respect of Figure 2, for example. Accordingly, the coverage area of the network slice may be the coverage area 200 described above.

The radio domain management node 506 and the core domain management node 508 are operable to obtain performance information for the network slice. The performance information is for one or more boundary TAs of the network slice. The boundary TAs may be the boundary TAs 202a-202f described above in respect of Figure 2, for example.

At least one of the radio domain management node 506 and the core domain management node 508 is operable to determine whether or not a TA in the network slice is a boundary TA. This determination may be made based on information received from the RAN 502. For example, each RAN node serving one or more cells in the RAN 502 may determine whether any of its cells are boundary cells. The RAN nodes may make this determination using any suitable methods, such as those described in WO 2020/074087 A1 , for example. The RAN nodes may indicate which of its cells are boundary cells to the radio domain management node 506 and/or the core domain management node 508. The radio domain management node 506 and/or the core domain management node 508 may aggregate this information on a TA level. It may thus be determined that, for example, an TA containing at least one boundary cell is a boundary TA and any TAs that do not have any boundary cells are not boundary TAs.

The radio domain management node 506 and/or the core domain management node 508 may associate each TA with a parameter indicating whether or not the TA forms part of the boundary of the coverage area. The parameter may take the form of a flag or Boolean for example, in which a value of TRUE (or 1) indicates that the TA is a boundary region and a value of FALSE (or 0) indicates that the TA is not a boundary region. Thus, on determining whether or not a TA is a boundary TA, the radio domain management node 506 and/or the core domain management node 508 may update the parameter associated with that TA based on the determination.

The performance information for the one or more boundary TAs may be, for example, the performance information described above in respect of any of Figures 2-4.

The performance information may be determined at (e.g. calculated or measured at) the radio domain management node 506 and/or the core domain management node 508. Alternatively, the performance information may be received from the RAN 502 and/or the core network 504 respectively.

For the first example described above in respect of Figures 2 and 3, RAN nodes in the boundary TAs 202c, 202d may increment a failure counter each time handover to a cell in the neighbouring TA 204 fails. This failure counter may be referred to as pmHoFailNotSupported. The RAN nodes in the TAs 202c, 202d may send their respective counters to a radio domain management node to aggregate the failure counter on a TA level. The failure counters may be reset at specified time intervals or whenever the coverage area of the network slice is changed, for example.

In another example, an SMF in the core network 504 may determine the performance information by monitoring the number of PDU sessions with wireless devices in a boundary TA and incrementing a counter each time a new PDU session is instantiated. The counter may be reset at specified time intervals or whenever the coverage area of the network slice is changed, for example.

At least one of the radio domain management node 506 and the core domain management node 508 are operable to send the performance information to an assurance system 510 (or assurance function) in the system 500. The assurance system 510 is operable to determine, based on the performance information, the demand for one or more services provided by the network slice. Thus, in examples in which the performance information comprises a total number of handover failures from a boundary region of the at least one network slice to a neighbouring region, the assurance system 510 may compare the number of handover failures to a minimum threshold. The assurance system 510 may thus determine whether or not the number of handover failures to the neighbouring region is sufficient to warrant adding the neighbouring region to the network slice.

In general, the assurance system 510 is operable to compare the performance information to one or more thresholds to assess the demand for one or more services provided by the network slice. In response to determining that the one or more thresholds (e.g. at least one of the one or more thresholds) are satisfied, the assurance system 510 issues a threshold breech notification to the system 500.

The threshold breech notification is received by a policy engine (e.g. a policy framework) 512 in the system. The policy engine 512, which is subscribed to receive such notifications, consumes the threshold breech notification. The policy engine 512 may be configured with one or more policies for managing a coverage area of the network slice. The policies may be specific to the particular network slice or they may be general to one or more network slices implemented in the system 500 (e.g. all of the network slices implemented in the system 500).

Based on the policies for the network slice, the policy engine 512 determines to change the coverage area 200 of the network slice. Based on this determination, the policy engine 512 sends a policy decision to the network slice orchestrator 514 (e.g. an End- to-End, E2E, Orchestrator). The policy decision instructs the network slice orchestrator 514 to add or remove a TA from the coverage area 200. Thus, for the first example described above in respect of Figures 2-3, the policy engine 512 may instruct the network slice orchestrator 514 to add the neighbouring TA 204 to the coverage area 200 of the network slice. For the second example described above in respect of Figures 2 and 4, the policy decision may instruct the network slice orchestrator 514 to remove the boundary TA 202c from the coverage area 200 of the network slice.

The policy decision may be sent directly or indirectly from the policy engine 512 to the network slice orchestrator 514. As illustrated, the policy decision may be sent via a customer facing service management node 516 in the system 500. The customer facing service management node 516 may be a business support system, BSS, for example. The customer facing service management node 516 may be operable to obtain operator input on the policy decision. The customer facing service management node 516 and the other nodes in the system 500 may be in different domains. For example, the customer facing service management node 516 may be in a communication service provider domain and the other nodes in the system 500 may be in a network operator domain. In a particular examples, the customer facing service management node 516 may be a BSS that is outside an operation support system.

Alternatively, the policy decision may be sent from the policy engine 512 to the network slice orchestrator 514 without passing through any intermediate nodes or other domains.

The network slice orchestrator 514 receives the policy decision and determines which radio domain management nodes need to be instructed to cause the change in coverage area. Although only one radio domain management node 506 is shown in Figure 5, the skilled person will appreciate that the system 500 may, in general, comprise one or more radio domain management nodes. The network slice orchestrator 514 may thus determine which of the radio domain management nodes in the system 500 are responsible for the TA to be added or removed from the network slice. In the illustrated example, the network slice orchestrator 514 determines that the radio domain management node 506 is responsible for the TA to be added or removed from the network slice and instructs the radio domain management node 506 to add or remove the TA to the network slice.

The radio domain management node 506 builds the new configuration and applies it to RAN nodes in the TA in the RAN 502. A configuration management (CM) function may be implemented in the radio domain management node 506 to provide this functionality, for example.

The RAN nodes in a TA may store information indicating which network slices they are a part of. Accordingly, in order to add or remove a TA from the coverage area of the network slice, the radio domain management node 506 may instruct RAN nodes in the TA to update this information.

For example, a RAN node in the RAN 502 may store Network Slice Selection Assistance Information (NSSAI) comprising one or more Single NSSAIs (S-NSSAI) indicating the network slices supported by the RAN node (e.g. the network slices that the radio access node is a part of). Each S-NSSAI may include a Slice/Service type (SST) referring to the expected behaviour of the network slice in terms of features and services; and may also include a Slice Differentiator (SD), which is optional information that complements the Slice/Service type(s) to differentiate between network slices of the same Slice/Service type.

Therefore, to add or remove a TA from the network slice, the radio domain management node 506 may initiate the addition or removal of the S-NSSAI for the network slice from the respective NSSAIs for the radio access nodes in the TA. For example, the radio domain management node 506 may send a message to the radio access nodes in the TA, instructing the radio access nodes to add or remove the S- NSSAI of the network slice.

The system 500 is thus operable to monitor the demand for one or more services provided by a network slice implemented in the system 500 and autonomously adapt the coverage area 200 of the network slice based on that demand.

Figure 6 shows a flowchart of an example of a method of changing a coverage area of a network slice in a communications network. The method is performed by a network node in the communications network. The communications network may be the communications network 100, for example.

The skilled person will appreciate that the network node may, in general, be a physical network node (e.g. an apparatus) or a virtual network node (e.g. a logical network node). Thus, for example, the network node may be implemented in software (e.g. as a virtual network function). The network node may be the policy engine 512 described above in respect of Figure 5, for example.

The method begins in step 602 in which the network node obtains performance information for one or more boundary regions defining at least part of a boundary of the coverage area.

The skilled person will appreciate that the coverage area of a network slice may be divided into one or more regions such as TAs or cells. For example, the coverage area of a network slice may comprise one or more of the TAs 202, 204 described above in respect of Figures 2-4. The regions forming the coverage area may be classified as either boundary regions or non-boundary regions. The boundary regions define at least a part of the boundary (e.g. an edge) of the coverage area. For example, any region in the coverage area of the network slice which is adjacent to or overlaps with another region that does not form part of the network slice may be a boundary region. Conversely, any region in the coverage area that is surrounded by other regions in the same network slice may be non-boundary region.

In general, at least one of the regions in the coverage area of a network slice is a boundary region. In particular examples the coverage area of a network slice may consist solely of boundary regions (as in the coverage area 200 illustrated in Figure 4, for example).

As described above in respect of Figures 2-4, in some examples, the regions defining the coverage area may be further divided into sub-regions. For example, the coverage area may be defined in terms of one or more TAs, and each of the TAs may comprise one or more cells. In these examples, a boundary region may be any region comprising at least one sub-region that forms part of the boundary. Thus, a boundary TA may be any TA comprising at least one cell forming part of the boundary or edge of the coverage area. The skilled person will appreciate that various methods may be used for identifying a boundary cell in a communications network, such as for example, the methods described in WO 2020/074087 A1 . Thus, for example, a boundary cell may be a cell that has at least one cell on its neighbour list that is in a different network slice.

The performance information for the one or more boundary regions is indicative of demand for the one or more services provided by the network slice. The performance information may be indicative for demand for services in the one or more boundary regions.

For example, the performance information may be indicative of an amount of network traffic in the one or more boundary regions. The performance information may be specific to the network slice. The skilled person will appreciate that, in general, a region in a network may be part of more than one network slice (e.g. the cell(s) served by the RAN node 104b described in respect of Figure 1 above are in both NS2 112 and NS3 1 14). Accordingly, traffic between wireless devices in that region and the network 100 may be distributed across multiple network slices. To account for this, the network node may use traffic information that is specific to the network slice. The performance information may thus indicate an amount of traffic between wireless devices in the boundary regions and other nodes in the network slice.

The skilled person will appreciate that there are various ways of quantifying network traffic. In particular, the performance information may indicate traffic volume or traffic intensity between nodes (e.g. wireless devices or RAN nodes) in the one or more boundary regions and nodes in other parts of the communications network 100.

For example, the performance information may relate to a number of PDU sessions provided by the one or more boundary regions (e.g. a number of PDU sessions between the network and one or more wireless devices in the boundary regions). The number of PDU sessions may, for example, the number of simultaneous PDU sessions at any one time (e.g. a peak number of simultaneous PDU sessions during a specified time period) or a total number of PDU sessions in the network slice in a specified time period.

The throughput for one or more wireless devices in the boundary regions may also indicate demand for the one or more services provided by the network slice. Accordingly, the performance information may additionally or alternatively relate to a throughput of one or more wireless devices in the boundary regions. For example, the performance information may comprise an upstream and/or downstream throughput (e.g. traffic volume) for the boundary regions. In particular examples, the throughput may be specific to one or more services implemented in the network slice. The network node may thus monitor the traffic volume for wireless devices in the boundary regions that is due to services provided in by the network slice.

In alternative examples, the performance information may be indicative of demand in one or more neighbouring regions in the network 100. That is, the performance information may indicate demand for the one or more services provided by the network slice in one or more regions that are not in the coverage area of the network slice when the method is performed (e.g. cells or TAs that are not in the network slice but are next to or overlapping with the coverage area of the network slice). In particular examples, the performance information relates to one or more failed handovers of one or more wireless devices from the one or more boundary regions in the coverage area to the one or more neighbouring regions. Handover of a wireless device from a first region in a network slice to a second region not in the same network slice may fail if the wireless device uses one or more services provided by the network slice that are not available in the second region. As a result, the incidence of handover failures may be indicative of demand for the service in the second region.

The skilled person will appreciate that there are various metrics that may be used to quantify handover failures. Thus, for example, the performance information may comprise a total number of handover failures (e.g. in a specified time period) or a time between handover failures.

The network node may obtain the performance information in step 602 by determining (e.g. calculating or measuring) the performance information at the node itself or by receiving the performance information from another node. In examples in which the method 600 is implemented in a policy engine (such as the policy engine 512), the policy engine may thus obtain performance information by receiving a threshold breech notification (such as that described above in respect of Figure 5) from an assurance system. The received threshold breech notification may indicate that there is demand for one or more services provided by the network slice in a region that is not currently within the coverage area of the network slice, for example. In an alternative example, the threshold breech notification may indicate that the demand for services in part of the coverage area is below a minimum threshold.

In step 604, the network node changes the boundary of the coverage area of the network slice based on the performance information. The network node may thus, for example, add or remove a region from the coverage area for the network slice.

The network node may determine that there is insufficient demand for one or more services provided by the network slice in a region of the coverage area and, based on that determination, remove that region from the coverage area. In examples in which the coverage area is defined in terms of a plurality of TAs, the network node may thus, for example, remove one or more TAs from the coverage area in response to determining that there is little or no demand for services in those TAs (e.g. the demand for services does not meet or satisfy a threshold value).

As described above, the demand for services provided by the network slice may be determined using traffic information for the one or more boundary regions, such as information relating to a number of PDU sessions and/or throughput of wireless devices in those regions. Thus, in step 604, the network node may compare this performance information to a corresponding threshold value. For example, the network node may determine that the number of PDU sessions for a boundary region does not satisfy the corresponding threshold value, and thus remove the boundary region from the coverage area.

In other examples, the network node decides to add a neighbouring region to the coverage area for the network slice in response to determining that there is sufficient demand for one or more services provided by the network slice in that region. Thus, for example, the network node may determine to include an additional RAN node in the network slice, in which the RAN node serves a region that is adjacent to or overlapping with the one or more boundary regions of the network slice.

The demand for services provided by the network slice in a neighbouring region may be determined using performance information relating to one or more failed handovers from boundary regions in the coverage area to the neighbouring region. For example, the network node may, in step 604, compare the number of failed handovers from a boundary region to the neighbouring region to a threshold number of handover failures (e.g. a minimum number of handover failures). If the number of failed handovers satisfies (e.g. exceeds) this threshold value, then the network node adds the neighbouring region to the coverage area. In an alternative example, the network node compares the time between successive handover failures to a maximum time between failures. As the time between handover failures may indicate the frequency of handover failure, the network node may add the neighbouring region to the coverage area in response to determining that the time between successive handover failures is below a threshold value. The network node may thus change a boundary of the coverage area by adding or removing a region from the coverage area. In cellular networks, the network node may thus, for example, add or a remove a TA or cell from the coverage area in step 604.

The network node may change the boundary of the coverage area directly or indirectly. The network node may thus change the boundary of the coverage area by instructing another node in the communications network to change the coverage area. For example, the policy framework 512 described above in respect of Figure 5 is configured to change a boundary of a coverage region by instructing the network slice orchestrator 514 to add or remove a TA (an example of a region) from the coverage area of the network slice. The network slice orchestrator 514 may send this instruction to the radio domain management node 506, causing the radio domain management node 506 to add or remove the indicated TA from the coverage area 200 (e.g. by adding or removing a radio access node from the network slice).

In particular examples, subsequent to step 604, the network node may re-determine which regions in the coverage area for the network slice are boundary regions. The network node may use any suitable methods for determining whether or not a region is a boundary region including, for example, the methods described above in respect of the radio domain management node 506 and the core domain management node 508 of Figure 5. The network node may thus, for example, update parameters (e.g. stored at or otherwise made available to the network node) associated with each region in the coverage area of the network slice, in which the parameters indicate whether or not the region is a boundary region.

Figure 7 shows a schematic diagram of a network node 700 for changing a coverage area of a network slice in a communications network according to examples of the disclosure. The network node 700 may be, for example, the policy engine 512 described above in respect of Figure 5.

The network node 700 comprises processing circuitry (or logic) 702. The processing circuitry 702 controls the operation of the network node 700 and can implement the method 600 described above with respect to Figure 6, for example. The processing circuitry 702 can comprise one or more processors, processing units, multi-core processors or modules that are configured or programmed to control the network node in the manner described herein. In particular implementations, the processing circuitry 702 can comprise a plurality of software and/or hardware modules that are each configured to perform, or are for performing, individual or multiple steps of the method described herein in relation to the network node 700.

Briefly, the processing circuitry 702 of the network node 700 is operable to: obtain performance information for one or more boundary regions defining at least part of a boundary of the coverage area, the performance information being indicative of demand for one or more services provided by the network slice. The processing circuitry 702 is further operable to change the boundary of the coverage area based on the performance information

Optionally, the network node 700 may comprise a memory (e.g. a machine- or computer-readable storage medium) 704. In some examples, the memory 704 of the network node 700 can be configured to store instructions (e.g. program code) that can be executed by the processing circuitry 702 of the network node 700 to perform the method described herein in relation to the network node 700. Alternatively or in addition, the memory 704 of the network node 700, can be configured to store any requests, resources, information, data, signals, or similar that are described herein. The processing circuitry 702 of the network node 700 may be configured to control the memory 704 of the network node 700 to store any requests, resources, information, data, signals, or similar that are described herein.

In some examples, the network node 700 may optionally comprise a communications interface 706. The communications interface 706 of the network node 700 can be for use in communicating with other nodes, such as other virtual nodes. For example, the communications interface 706 of the network node 700 can be configured to transmit to and/or receive from other nodes requests, resources, information, data, signals, or similar. The processing circuitry 702 of the network node 700 may be configured to control the communications interface 706 of the network node 700 to transmit to and/or receive from other nodes requests, resources, information, data, signals, or similar.

In the illustrated example, the processing circuitry 702, the machine-readable medium 704 and the interfaces 706 are operatively coupled to each other in series. In other examples, these components may be coupled to each other in a different fashion, either directly or indirectly. For example, the components may be coupled to each other via a system bus or other communication line.

Claims

22 Claims

1 . A method performed by a network node for changing a coverage area of a network slice in a communications network, the method comprising: obtaining performance information for one or more boundary regions defining at least part of a boundary of the coverage area, the performance information being indicative of demand for one or more services provided by the network slice; and changing the boundary of the coverage area based on the performance information.

2. The method of any of the preceding claims, wherein the performance information is indicative of demand for one or more services in the one or more boundary regions.

3. The method of claim 2, wherein changing the boundary of the coverage area comprises removing at least one of the boundary regions from the coverage area.

4. The method of claim 3, wherein the at least one boundary region is removed in response to determining, based on the performance information, that demand for the one or more services in the at least one boundary region is below a first threshold value.

5. The method of any of claims 2-4, wherein the performance information relates to one or more of the following: a number of packet data unit sessions provided by the at least one boundary region; an upstream throughput of one or more wireless devices within the at least one boundary region; and a downstream throughput of one or more wireless devices within the at least one boundary region.

6. The method of any of the preceding claims, wherein the performance information indicates demand for services provided by the network slice in a neighbouring region not in the coverage area of the network slice, and wherein changing the boundary of the coverage area comprises adding the neighbouring region to the coverage area.

7. The method of claim 6, wherein the performance information relates to one or more failed handovers of one or more wireless devices from the one or more boundary regions to the neighbouring region.

8. The method of claim 7, wherein the performance information comprises a number of failed handovers of the one or more wireless devices from the one or more boundary regions to the neighbouring region, and the method further comprises: comparing the number of failed handovers to a second threshold; and based on the comparison, adding the neighbouring region to the coverage area.

9. The method of any of the preceding claims, further comprising, subsequent to changing the boundary of the coverage area, updating which regions in the coverage area are identified as boundary regions defining at least part of the boundary of the coverage area.

10. The method of any of the preceding claims, wherein each of the boundary regions comprises one or more tracking areas or cells in a radio access network.

11. A computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out a method according to any of the preceding claims.

12. A carrier containing a computer program according to claim 11 , wherein the carrier comprises one of an electronic signal, optical signal, radio signal or computer readable storage medium.

13. A computer program product comprising non transitory computer readable media having stored thereon a computer program according to claim 11 .

14. A network node for changing a coverage area of a network slice in a communications network, the network node comprising a processor and a memory, the memory containing instructions executable by the processor such that the network node is operable to: obtain performance information for one or more boundary regions defining at least part of a boundary of the coverage area, the performance information being indicative of demand for one or more services provided by the network slice; and change the boundary of the coverage area based on the performance information.

15. The network node of claim 14, wherein the performance information is indicative of demand for one or more services in the one or more boundary regions.

16. The network node of claim 15, wherein changing the boundary of the coverage area comprises removing at least one of the boundary regions from the coverage area.

17. The network node of claim 16, wherein the at least one boundary region is removed in response to determining, based on the performance information, that demand for the one or more services in the at least one boundary region is below a first threshold value.

18. The network node of any of claims 15-17, wherein performance information relates to one or more of the following: a number of packet data unit sessions provided by the at least one boundary region; an upstream throughput of one or more wireless devices within the at least one boundary region; and a downstream throughput of one or more wireless devices within the at least one boundary region.

19. The network node of any of claims 14-18, wherein the performance information indicates demand for services provided by the network slice in a neighbouring region not in the coverage area of the network slice, and wherein changing the boundary of the coverage area comprises adding the neighbouring region to the coverage area.

20. The network node of claim 19, wherein the performance information relates to one or more failed handovers of one or more wireless devices from the one or more boundary regions to the neighbouring region. 25

21 . The network node of claim 20, wherein the performance information comprises a number of failed handovers of the one or more wireless devices from the one or more boundary regions to the neighbouring region, and the method further comprises: comparing the number of failed handovers to a second threshold; and based on the comparison, adding the neighbouring region to the coverage area.

22. The network node of any of claims 14-21 , further comprising, subsequent to changing the boundary of the coverage area, updating which regions in the coverage area are identified as boundary regions defining at least part of the boundary of the coverage area.

23. The network node of any of claims 14-22, wherein each of the boundary regions comprises one or more tracking areas or cells in a radio access network.

24. A network node for changing a coverage area of a network slice in a communications network, wherein the network node is configured to: obtain performance information for one or more boundary regions defining at least part of a boundary of the coverage area, the performance information being indicative of demand for one or more services provided by the network slice; and change the boundary of the coverage area based on the performance information.