Page 29 - ITU-T Focus Group IMT-2020 Deliverables

ITU-T Focus Group IMT-2020 Deliverables 2

NOTE – Users can obtain services from one or more specific network slices simultaneously based on
subscription and/or UE context and/or local policy. A UE may access multiple slices simultaneously via a single
RAN, and may provide network slice selection assistance information to the network.
[REQ] The network architecture for IMT-2020 is required to have the capability to meet the service-specific
security assurance requirement in a single network slice, rather than the whole network slices.
[REQ] The network architecture for IMT-2020 is recommended that network functions are virtualized and it
should support dynamic scale-in /scale-out per operator’s policies.

9.2 Fixed-mobile converged networks

9.2.1 Description
The use of multiple heterogeneous radio access networks, including WLAN networks, and their interworking
with each other in existing IMT networks are becoming prevalent with various approaches: LTE/WLAN link
Aggregation (LWA), interworking with ePDG or TWAG (trusted wireless access gateway), etc. The trend is also
expected to be continued in IMT-2020 networks, but with more advanced and efficient ways. The multi-
connectivity through the multiple available radio access networks improves the robustness of the network
as well as the throughput performance. Especially, the dual connectivity of an existing IMT-network and a
new IMT-2020 network will help ensure the smooth introduction of IMT-2020 networks.

The IMT-2020 network is envisioned to be an access network-agnostic architecture whose core network will
be a common unified core network for emerging new radio access technologies for IMT-2020 as well as
existing fixed and wireless networks (e.g., WLAN). The access technology-agnostic unified core network
should be accompanied by common control mechanisms which are decoupled from access technologies.
9.2.2 Requirements

[REQ] The network architecture for IMT-2020 is required to support that the signaling on different radio
access networks is independent resulting in inevitable duplications in signaling for attachment,
authentication, and mobility in each radio access networks.

[REQ] The network architecture for IMT-2020 is required to support newly-defined RATs for IMT-2020,
evolved IMT-advanced RATs, WLAN access networks, and fixed broadband access networks.

[REQ] The network architecture for IMT-2020 is required to minimize access dependency in order to allow
independent evolutions of core network and access networks.

[REQ] The network architecture for IMT-2020 is required to support simultaneous multi-RAT connectivity,
optimization and resiliency of diversified MFH & MBH for the extreme traffic/connection density, enhanced
multi-RAT coordination to ensure seamless user experience while mobile, standardized interfaces for multi-
operator/shared use of infrastructure, etc.
[REQ] The network architecture for IMT-2020 is required to support more flexible and optimized multi-RAT
interworking architecture, although traffic steering and the selection of best access technology in existing
IMT networks is considered.
[REQ] The network architecture for IMT-2020 is required to support the multi-connectivity through the
multiple available radio access networks that improves the robustness of the network as well as the
throughput performance.

[REQ] The network architecture for IMT-2020 is required to consider fixed broadband access networks as an
access network of IMT-2020 to interwork with other radio access networks.
NOTE – A converged access-agnostic core (i.e., where identity, mobility, security, etc. are decoupled from the
access technology), which integrates fixed and mobile core, is envisioned as a direction of IMT-2020.
Therefore, the IMT-2020 network architecture should be studied to support a true fixed and mobile
convergence ensuring a seamless user experience within the fixed and mobile domains.

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