Page 337 - 5G Basics - Core Network Aspects

Core network aspects 1

be desirable to utilize the circuit switched domain in 2G for the voice application, while data applications
utilize the packet switched domain (WLAN, 3G, WiMAX or LTE), the so-called multi-connection coordination.
This strategy will help offload data intensive applications from 2G. As a result, the following is required:
1) The network is required to support voice applications in the circuit switched (CS) domain and data
applications in the packet switched (PS) domain. This separation of CS and PS traffic types shall be
able to operate concurrently.
2) The network and UE are required to support the CS and PS applications running simultaneously over
different access technologies.

6.4 Service transfer

In the multi-connection environment, the UE may have more than one active connection simultaneously to
different access network connections.

In case of network congestion or loss of radio signal in the access network connections, the network is
required to dynamically control the user access and resource allocation to obtain the optimal distribution of
applications and/or IP flows. This is achieved according to multi-connection policies generated by both the
user and network.
Service transfer is one mechanism required to achieve this capability thus further providing service continuity
to the user and application during the service transfer. Summarizing these requirements:
1) Service continuity is required during service transfer, in order to minimize the time taken during
radio handover or new bearer establishment.
2) A resource pre-allocation mechanism is required to reduce the time of the service transfer.
3) A data forwarding mechanism is also required to keep data integrity.
NOTE – The service transfer depends on the scenario, operators, users, the properties of the application and service.

6.5 Service decomposition and composition

Service decomposition is required to support a number of scenarios provided in [b-ITU-T Y-Sup.9]. A service
supported by the multi-connection capability can be split into several service components in order to be
transmitted through different access network connections.

Likewise, service composition is required to support a number of scenarios provided in [b-ITU-T Y-Sup.9].
Thus, the service components in a call split through different access network connections can be composed
into one service in a unified way to be transmitted in one or a lesser number of access network connection(s).
The following encompasses additional requirements applicable to service composition and decomposition,
it is required to:
1) Maintain the previous state in the service after composing or decomposing the service.
2) Synchronize the service components belonging to one application while in the process of composing
or decomposing a service; e.g., the packet rates of the different service components requiring
synchronization.
3) Assign a unique identifier to each service component in order to identify the decomposed and
composed service.
4) Add or remove a new service component into/from an active call.

6.6 Multi-connection related policies
Policy is needed to determine how to use multiple access network connections. There can be several kinds
of policies deployed in the multi-connection capability. Each layer may have its own policy for choosing the
related connections. Therefore, it is necessary to have a coordination mechanism to ensure that all policies
can work together in a coherent manner. The following policies are required to be supported in a multi-
connection environment:

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