Page 338 - 5G Basics - Core Network Aspects

1 Core network aspects

1) QoS policy – This policy is used to match the service and its access network connections with
equivalent quality. It is also used as a factor to be considered in the access network selection.
2) Access network selection policy for data sending and receiving – This policy is based on application,
service, user preference, operator policy, security consideration, access network status and
availability.

3) Service transfer policy – Transferring a service between multiple accesses is required to be validated
by the operator's policies. These policies include:

• Access related policy: For example, a given service may be transferred between specific access
technologies, but such transfer of a service may be forbidden or restricted on some other access
technologies;
• Service component related policy: For example, only some service components are eligible to
service transfer such as service components (e.g., voice or video) having high QoS requirements,
while other service components may not be eligible to service transfer.
• Subscriber related policy: Service transfer may be applicable only to certain types of subscribers,
not for all subscribers.

The use of the above policies varies depending on the specific scenarios of multi-connection. Appendix III
provides an analysis of how these policies can be used in the scenarios described in [b-ITU-T Y-Sup.9].

6.7 QoS requirements in multi-connection
In a multi-connection capable network, the UE and the network are required to be aware of the interactions
created by the number of simultaneous accesses provided to the application and therefore each associated
QoS. The combination or resulting QoS is required to portray the combined QoS involved in each specific
service component.
Specifically, some QoS multi-connection requirements for the multi-connection scenario described in [b-ITU-
T Y-Sup.9] are:
1) In Scenarios A, B, and C, service control is required to provide to the application a resulting QoS that
is at least as good as the QoS of any individual access technology under its control.
2) In Scenarios A, and B, access control is required to deliver access technology QoS to the service
control that is at least as good as QoS of any individual access link under its control.
In Scenario A, the access point is required to deliver QoS to the access control that is at least as good as the
QoS of any individual access link under its control.

6.8 QoS mapping among different access networks

Different access technologies have different link-layer QoS mechanisms. The multi-connection
communication requires mechanisms to minimize service degradation among multi-connections. According
to the QoS policies specified for each access technology (i.e., [b-IEEE 802.16], [b-IEEE 802.11], GPRS, UMTS,
and LTE), QoS classes are required to be allocated both for the service components and for their respective
accesses. The bandwidth is required to be constrained by the mapping policy of the QoS management. An
example of such mapping is provided in Appendix I.

6.9 Access network selection

Access network selection includes discovery and selection [b-IETF RFC 5113]. In a multi-connection
environment, discovery of an access network can use existing access network discovery mechanisms
developed in IETF, IEEE or 3GPP. However, choosing the best access networks needs more capabilities. Due
to the characteristics of multi-connections, not only a single access network but also multiple access networks
can be chosen. Choosing the best ones needs more complicated but efficient capabilities to support various
QoS and policy mechanisms.

328