The EPS provides a user with an IP connection to PDN for Internet access, as well as to run services, such as VoIP. EPS bearer is usually associated with QoS. Some carriers may be installed to the user, in order to ensure that the various different streams or PDNs QoS connection. For example, a user may participate in the call, voice (VoIP) at the same time, the Web browsing or file transfer protocol (FTP) to download.
Carrier VoIP will provide QoS for voice call and bearer of best-effort be suitable for Web browsing or FTP session. The network must also provide adequate security and privacy for the user and network protection against fraudulent use.
Release 9 LTE has a number of additional features. To meet regulatory requirements for commercial Voice Services, such as support for IMS emergency calls and UE positioning were introduced. Improvements to the home cells (HeNBs) were also introduced in version 9.
All of these features are supported by using multiple network elements EPS with diifferent roles. Figure shows both the high-level architecture for the network, including the network elements and standardized interfaces. At a high level, the network consists of CN (EPC) and network access (E-UTRAN).
While CN has many logical nodes, network access is essentially just one node, developed NodeB (eNodeB) that connects to the EEC. Each of these elements are connected through network interfaces, which are standard to enable commercial interoperability.