t functions including dedicated bearer establishment [31]. The NAS signaling terminates at the MME and it is also responsible for generation and allocation of temporary identities to the UEs. It verifies the authorization of the UE to camp on the service provider's Public Land Mobile Network (PLMN) and enforces UE roaming restrictions. Inter Cell RRM Radio Bearer Control Connection Mobility Control NAS Security Radio Admission Control eNB Measurement Idle State Mobility Configuration & Provision Management Dynamic Resource EPS Bearer Control Allocation (Scheduler) UE IP Address Mobility Allocation Anchoring Packet Filtering Internet E-UTRAN FIGURE 2-10 The functional split between E-UTRAN and EPC [31] 2.8 Overview of 3GPP evolved packet core network architecture S1-MME Gateway S1-MME Evolved Packet Network Security Gateway Management System (SeGW) FIGURE 2-11 E-UTRAN HeNB logical architecture [31] The Serving Gateway (S-GW) routes and forwards user data packets, while also acting as the mobility anchor for the user-plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies. The S-GW functions include 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 routing and forwarding, and transport-level packet marking in the uplink and the downlink [31]. The Packet Data Network Gateway (P-GW) provides connectivity of the UE to external packet data networks by being the point of exit and entry of traffic for the UE. A UE may have simultaneous connectivity with more than one P-GW for accessing multiple packet data networks. The P-GW functions include per-user packet filtering, lawful interception, UE IP address allocation, and trans- port-level packet marking in the downlink [31]. The baseline 3GPP network architecture can be further extended to include femto-cells. [31] Figure 2-11 shows a logical netw