A RAN Congestion Awareness Function (RCAF) is an element which reports RAN User Plane Congestion Information
(RUCI) via the Np interface to the PCRF to enable the PCRF to take the RAN user plane congestion status into account
for policy decisions.
The RF determines the value of the network resource usage (described in the charging event received
by the OCF from the network) on behalf of the OCF. To this end, the OCF furnishes the necessary information,
obtained from the charging event, to the RF and receives in return the rating output (monetary or non-monetary units),
via the Re reference point.
The Radio Network System (RNS) is the system of base station equipments (transceivers, controllers, etc.) which is
viewed by the MSC through a single Iu-interface as being the entity responsible for communicating with Mobile
Stations in a certain area.
Similarly, in PLMNs supporting GPRS, the RNS is viewed by the SGSN through a single Iu-PS interface. When Intra Domain Connection of RAN Nodes to Multiple CN Nodes is applied, an RNS may connect to
several MSCs by several Iu-CS interfaces, and an RNS may connect to several SGSNs by several Iu-PS interfaces.
The functionality for the Iu-CS interface is described in
TS 25.410 and for the Iu-PS interface in
TS 23.060. The
radio equipment of a RNS may support one or more cells. A RNS may consist of one or more base stations. The RNS
consists of one Radio Network Controller (RNC) and one or more Node B.