For the purposes of the present document, the terms given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

For the purposes of the present document, the following symbols apply:

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905. ANDSP CSC CSP DN DNN ECS EEC eMBB EPC GST MIoT MPS MNO MVNO NEST NOP NRM NSaaS NSC NSCE NSI NSP NSSI NSSP NWDAF PDU ProSe ProSeP URSP V2X V2XP

The following assumptions apply to the present document:

1. Possible and efficient solutions based on network slicing are sought to support the use cases listed in clause 5 and many others that also require differentiated QoS for their application streams. Network slicing may not be the only solution to support these use cases, but is one possible solution.
2. Service requirements relating to network slicing specified in TS 22.261 and TR 23.700-99 are considered for studying possible issues in relation to 5G Media Streaming.

Clause 5.12 of TR 26.804 provides a brief overview of network slicing feature standardization in different 3GPP groups, areas of study related to 5G Media Streaming for specifying network slicing extensions, and potential open issues. This clause describes different slice management processes in a little more detail that are relevant for specifying the media streaming aspects of network slicing.

TS 28.530 and TS 28.531 specify general concepts related to network slicing and slice life cycle management including specification of roles related to network slicing such as the CSC, CSP, NOP, NSC, and NSP. A network operator can perform both the roles of a CSP and NSP. A request from a CSC or NSC to the CSP or the NSP respectively for setting up a network slice is in the form of a set of slice attributes that represents the service requirements for the service that the customer intends to provide to its users. The GSM Association describes a GST template [5] which specifies a set of attributes that characterize a given type of network slice/service. The slice customer prepares a NEST based on GST attributes and forwards it to the NSP for slice orchestration. A NEST is a GST filled with values. A study on GST attributes is specified in TR 23.700-40, and a reference to GST attributes is included in clause 5.15.2.2 of TS 23.501. GST attributes and NEST are also discussed in study on network slice capability exposure for application enablement (NSCALE) in TR 23.700-99. The normative specification for this work is being specified in TS 23.435. GST attributes, as defined in [5], are categorized into two types:

• Character attributes: These attributes typically characterize a slice (e.g., throughput, latency, APIs etc.). The character attributes can be further classified as relating to performance, function, or control and management
• Scalability attributes: These attributes provide information about the scalability of a slice (e.g., number of UEs)

The CSP/NSP translates the NEST to service requirements for a set of subnets (e.g., core, transport network, RAN) using the slice NRM as described in TS 28.530, TS 28.541, TS 28.542 [11]. Based on individual slice subnet requirements, slice subnet resources are provisioned using slice orchestration operations for creating and managing NSI and NSSI resources as defined in TS 28.531. Such operations include:

• Creation/modification/termination of NSI instances.
• Creation/modification/termination of NSSI instances.
• Creation/modification/termination of 3GPP NF instances.

Management and orchestration concepts such as provisioning management services, fault supervision management services, and performance assurance management services in addition to management service specification on the above slice resources are specified in TS 28.532. TS 28.545 and TS 28.546 [14] describe fault supervision aspects of management and orchestration of networks and network slicing. TS 23.501 and TS 23.502 specify control plane architecture and procedures on enabling the connection of the UE to the above provisioned network slices including establishment of PDU sessions through those slices to the intended DNN. TS 23.503 describes the data model for URSP rules and NSSP policies that enable UE application traffic to be routed through the provisioned network slices to the respective DNNs. In addition, a study on network slice capability exposure for application layer enablement is described in TR 23.700-99. The application layer enablement architecture in TS 23.700-99 is based on the Service Enabler Architecture Layer for Verticals (SEAL) whose functional architecture and information flows are specified in TS 23.434. One of the key issues under study in TS 23.700-99 is whether a more concise approach to managing the lifecycle of network slices exposed to the application layer with additional functionality for verticals can be defined. One of the solutions being studied in clause 6.1.1 of TS 23.700-99 is to interface the network slice capability enablement server with the 5G system in order to perform all the network slice lifecycle management operations defined in TS 28.530 and TS 28.531. With this capability, applications of different verticals can interface with the network slice capability enablement server for all network slice related operations. TS 27.007, in clause 10.1, describes how via AT commands the UE is able to set network slice preferences.

TR 23.700-99 documents several key issues and candidate solutions in addition to enabling network slice lifecycle management operations using the network slice capability enablement server. Some of the key issues relevant to that study are the following:

• Discovery and registration aspects for management service exposure.
• Network slice fault management capability.
• Communication service management exposure.
• Application layer QoS verification capability enablement.
• Network slice related performance and analytics exposure.
• Network slice capability exposure in the edge data network.
• Delivery of existing network slice information to the trusted third party.
• Network slice creation to the third party and UE.

In addition to the above information available at the network slice capability enablement server, TS 29.520 specifies the stage-3 definition of NWDAF Services of the 5G System and provides a data model for network slice information that NWDAF can provide to authorized customers. Such information can also be used as network slice capability information.