centre, stores the subscription-related information to
support the network entities handling calls and sessions.
It generates fresh key material over demand.
Serving Gateway
S-GW is the local mobility anchor, controlling the
packet routing and forwarding tasks, beside of other
transport level functions. It implements quality-ofservice
(QoS) functions and lawful interception features.
Packet Data Network Gateway
P-GW acts as intermediate between the operator
network and Internet, providing IP address for each
UE and recording service charges.
Serving GPRS Support Node
SGSN provides compatibility with packet switching
services of old access networks, such GERAN (GSM
system) or UTRAN (UMTS system).
On the other hand, the radio access network acts as a
link between the User Equipment (UE) and the core network.
EUTRAN Node B (eNB) entities provide services to the end
user, by means of the radio channels. After release 10, support
for Relay Nodes (RNs) and Home EUTRAN Node B (H-eNB)
or femtocell are added to provide a wide coverage area without
minimising QoS. A group of H-eNBs may be gathered and
addressed to a Home EUTRAN Node-B Gateway, reducing
the number of interfaces linked directly with the core network.