Page 339 - 5G Basics - Core Network Aspects

Core network aspects 1

Access network selection of multi-connection is required to provide consistent QoS, overall network stability
(load balance) and user satisfaction (select access technology based on end-user's preference). In selecting
the discovered access networks, the following considerations are required:
1) The QoS requirements of the flows, e.g., bandwidth, delay or loss rate.
2) The capabilities and availability of the UE, e.g., memory, battery, CPU or available interface.
3) The capabilities and availability of access resources, e.g., access technology type, bandwidth, loss
rate, delay, jitter, power consumptions or received signal strength (RSS).
4) The load-status of the access network, e.g., number of users.
5) User's preferences, e.g., cost, interface preference.

6) Operator's policies described in clause 6.6.

6.10 Access network monitoring
In order to efficiently provide access network selection or changing of a currently active access network, the
status information of the currently active access network needs to be monitored, such as physical layer
parameters including available bandwidth, modulation and coding scheme (MCS) level, radio strength status.
The access network information is required to be forwarded to the appropriate functions, periodically or on
demand.

6.11 Identifying and binding of IP flows
Support of multiple connections in the IP network faces problems, such as identifying IP flows and binding
them to different access network connections. To solve these problems, the following is required:
1) Classifying of IP flows – All packets belonging to a particular flow are required to have a set of
properties. These properties are defined as follows:
• One or more packet header field (e.g., destination IP address), transport header field (e.g.,
destination port number), or application header field (e.g., RTP header fields).
• One or more characteristics of the packet (e.g., number of MPLS labels).
• One or more fields derived from packet treatment (e.g., next hop IP address or the output
interface).
A packet is defined to belong to a flow if it completely satisfies all the defined properties of the flow.
2) Identifying of IP flows – In the multi-connections environment, the UE and network need to
distinguish IP flows. It is required to classify all kinds of current identifiers of the UE, service data
and user, such as IP address, and then choose a proper one or design a new one to identify the IP
flows in a multi-connection environment.

3) Binding of IP flows – The connections are used to carry certain IP flows, so IP flows marked by their
identifiers are required to be bound to proper connections.

6.12 Charging and accounting in multi-connection
The charging and accounting are required to support the operator's need to collect and process information,
such that users can be charged for the services provided in the multi-connection environment. Based on the
NGN charging requirements [ITU-T Y.2233], in the multi-connection environment, it is also required to
provide aggregated charging; i.e., the utilization of each connection is considered, and the sum of all
connections' utilization determines the ultimate charging data for the user. The detailed requirements are
summarized below:
1) Offline charging or online charging is required to be supported in multi-connection. They support
the collection of data for later processing (offline charging), as well as near-real-time interactions
with applications, such as for pre-paid services (online charging).

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