Why Requirements on the EPC in LTE?
A (rather long) list of general requirements has been set up as guidelines for the standardization work related to the EPC. Some of those are:
• 3GPP and non-3GPP access systems shall be supported.
• Scalable system architecture and solutions without compromising the system capacity (e.g. by separating CP from UP).
• CP response time shall be such that the UE can move from an idle state to one where it is sending/receiving data in less than 200 ms.
• Basic IP connectivity is established during the initial access phase (hence, the UE is ‘always-on’).
• The Mobility Management (MM) solution shall be able to accommodate terminals with different mobility requirements (fixed, nomadic and mobile terminals).
• The MM functionality shall allow the network operator to control the type of access system being used by a subscriber.
• MM procedures shall provide seamless operation of both real-time (e.g. VoIP) and non real-time applications.
• In order to maximise users’ access opportunities, the architecture should allow a UE that is roaming to use a non-3GPP access (e.g. WLAN) network with which the VPLMN has a business agreement. For example, it should be possible for a user to use a WLAN access network with which only the visited operator has a direct relationship (not the home operator).
• The evolved system shall support Ipv4 and Ipv6 connectivity.
• Access to the evolved system shall be possible with R99 USIM. (Please note that this does not explicitly allow access using SIM)
• The authentication framework should be independent from the used access network technology.
• Radio interface multicast capability shall be a built-in feature.
• The SAE/LTE system shall support network-sharing functionality.
• It shall be possible to support service continuity between IMS over SAE/LTE access and the Circuit Switched (CS) domain.
• It shall be possible for the operator to provide the UE with access network information pertaining to locally supported 3GPP and non-3GPP access technologies.