S-GW Functions

The Serving Gateway (S-GW) hosts the following functions (see 3GPP TS 23.401 [17])

• The local Mobility Anchor point for inter-eNB handover;
• Mobility anchoring for inter-3GPP mobility;
• E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure;
• Lawful Interception;
• Packet routeing and forwarding;
• Transport level packet marking in the uplink and the downlink;
• Accounting on user and QCI granularity for inter-operator charging;
• UL and DL charging per UE, PDN, and QCI.