Page 36 - ITU-T Focus Group IMT-2020 Deliverables

2 ITU-T Focus Group IMT-2020 Deliverables

Appendix I

Use cases of IMT-2020
(This appendix does not form an integral part of this Recommendation.)

I-1 Network slicing with shared Core Network instance
Network slice instance is a set of network functions, and resources to run these network functions, forming
a complete instantiated logical network to meet certain network characteristics. The function in a network
slice instance can include RAN functions and Core Network (CN) functions. In IMT-2020 architecture, there
are two types of core network slice instance listed as follows:
a) Dedicated CN instance: All the network functions belong to this CN instance are deployed only
serving for or associated with one network slice instance, even though the functions are the same
with ones of other network slice instances, e.g. CN instance A.
b) Shared CN instance: Different shared CN instances can share part of network functions, e.g. CN
instance B and C.
Therefore, there are two kinds of network slicing use cases considering two types of CN shown in Fig. I-1.

Dedicated CN Instance A
UE A RAN Instance A
NF 1 NF 2 NF 4

Shared CN Instance
Shared CN Instance B

NF 4

NF 2

UE B RAN Instance B NF 1

NF 2

NF3

Shared CN Instance C

Figure I-1 - Network slicing with shared CN instance

As shown in Figure I-1, a CN instance is made up of multiple network functions. For the dedicated CN instance,
all the network functions are dedicated to the CN instance. For the shared CN instance, part of the network
functions can be shared among different CN instances. There exists something difference in the identification
and selection mechanisms of CN instance. For dedicated CN instance, network slice selection function may
be not necessary. However, for the shared CN instance, the shared network function is required to find out
the next following network function in the corresponding CN instance if need. For shared CN instance, how
to realize the isolation of shared network functions among different CN instances is should also be
considered.

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