 LR that is associated with the anchor PC. The LR entry is created when an MS enters Idle State. It is required to perform location update when an Idle State MS moves and crosses the boundary of its current paging group. 2.8 OVERVIEW OF 3GPP EVOLVED PACKET CORE NETWORK ARCHITECTURE The Third Generation Partnership Project (3GPP) initiated work on Long-Term Evolution (LTE) in late 2004. The Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) has substantially improved end-user throughputs, sector capacity, and has reduced user-plane and control-plane latencies, bringing significantly improved user experience with full mobility. With the emergence of Internet protocol as the protocol of choice for carrying all types of traffic, 3GPP LTE provides support for IP-based traffic with end-to-end Quality of Service (QoS). Voice traffic is supported mainly as voice-over-IP, enabling integration with other multimedia services. Initial deployments of 3GPP LTE are expected by 2011, and commercial availability on a larger scale will likely happen a few years later. Unlike its predecessors, which were developed within the framework of Release 99 UMTS architecture, 3GPP has specified the Evolved Packet Core (EPC) architecture to support the E-UTRAN through reduction in the number of network elements and simplification of functionality, but most importantly allowing for connections and handover to other fixed and wireless access technologies, providing the network operators with the ability to deliver a seamless mobility experience. The main objectives of 3GPP LTE were to minimize the system and User Equipment (UE) complexities, to allow flexible spectrum deployment in the existing or new frequency bands, and to enable coexistence with other 3GPP radio access technologies. Some general principles taken into consideration in the design of E-UTRAN architecture, as well as the E-UTRAN interfaces, are as follows [31]: Signaling and data transport networks are logically separated; E-UTRAN and EPC functions are fully separated from