MOBILITY MANAGEMENT ENTITY (MME)
The MME is really a signaling-only entity, thus user IP packets do not glance at the MME. Its main function is to manage the UE's mobility. In addition, the MME also performs authentication and authorization; idle-mode UE tracking and reachability; security negotiations; and NAS signaling. An edge of an separate network element for signaling is always that operators can grow signaling and traffic capacity independently. A comparable benefit will also be accomplished in HSPA Release 7's direct-tunnel architecture, the place that the SGSN gets to be a signaling-only entity.
EFFICIENT QoS
A vital aspect for virtually every all-packet network is often a mechanism to guarantee differentiation of packet flows based on its QoS requirements. Applications for instance video streaming, HTTP, or video telephony have particular QoS needs, and should receive differentiated service above the network. With EPS, QoS flows called EPS bearers have established yourself between UE and also the P-GW. Each EPS bearer is a member of a QoS profile, and is made up of a radio bearer and a mobility tunnel. Thus, each QoS IP flow (e.g., VoIP) will be of the different EPS bearer, and also the network can prioritize packets accordingly. The QoS procedure for packets arriving from the Internet is just like that regarding HSPA. When receiving an IP packet, the P-GW performs packet classification according to parameters such as rules received in the PCRF, and sends it through the proper mobility tunnel. Based on the mobility tunnel, the eNB can map packets to your appropriate radio QoS bearer.
EPS SEAMLESS MOBILITY
Seamless mobility is clearly an essential consideration for wireless systems. Uninterrupted active handoff across eNBs may be the first scenario one typically considers. However, other scenarios such as handoffs across core networks (i.e., P-GW, MME), transfer of access technologies, and idle mobility can also be important scenarios paid by EPS.
SEAMLESS ACTIVE HANDOFFS
EPS enables seamless active handoffs, supporting VoIP along with real-time IP applications. As there is no RNC, an interface between eNBs is used to compliment signaling for handoff preparation. Moreover, the S-GW behaves as an anchor, switching mobility tunnels across eNBs. A serving eNB maintains the coupling between mobility tunnels and radio bearers, and as well maintains the UE context1. As preparation for handoff, the original source eNB (eNB 1) sends the coupling information and the UE context to the target eNB (eNB 2). This signaling is triggered by a radio measurement in the UE, indicating that eNB 2 incorporates a better signal. Once eNB 2 signals that it must be ready to perform the handoff, eNB 1 commands the UE to switch the radio bearer to eNB 2. To the eNB handoff to accomplish, the S-GW must update its records together with the new eNB that is serving the UE. For this phase, MME coordinates the mobility-tunnel switch from eNB 1 to eNB 2. MME triggers the update at the S-GW, according to signaling received from eNB 2 indicating that the radio bearer was successfully transferred.
Visit Session Persistence or Seamless connectivity for more.