 context and identity as well as authenticates and authorizes users. The User Plane Entity (UPE) that manages the user data path, including parameters of the IP service and routing. The 3GPP Anchor is a functional entity that anchors the user plane for mobility between the 2G/3G (GSM/UMTS) access system and the LTE access system. The SAE Anchor is a functional entity that anchors the user plane for mobility between 3GPP access systems and non-3GPP access systems. Evolved PDG (ePDG) comprises the functionality of a packet data gateway. The Policy Control and Charging Rules Function (PCRF) that manages QoS aspects. The Home Subscriber Server (HSS), which is the database of user subscription information. SAE will use IMS as a component and manage QoS across the whole system which will be essential in providing a rich set of multimedia services. Support for legacy 2G and 3G 3GPP networks via SGSN. Next Generation Mobile Communications Ecosystem 8.2.1.6.3 Reference Points A set of reference points are also defined to provide information transfer between the elements. Some key reference points are as follows: S1: It provides access to Evolved RAN radio resources for the transport of user plane and control plane traffic. S1-U serves as a reference point between E-UTRAN and Serving GW for the per bearer user plane tunneling and inter eNodeB path switching during handover. S1-MME serves as a reference point for the control plane protocol between E-UTRAN and S2a: It provides the user plane with related control and mobility support between trusted non 3GPP IP access and the packet gateway. S2b: It provides the user plane with related control and mobility support between ePDG and the SAE Anchor. S3: It enables user and bearer information exchange for inter 3GPP access network mobility in idle and/or active state (between SGSN and MME). It is based on Gn reference points as defined between SGSNs. S4: It provides related control and mobility support between GPRS Core and the 3GPP anchor function of Serving GW and is based on G