Dear community friends, hello!
Today I'm going to share with you the EPS architecture.
EPS Network Architecture
Latest 3G UMTS evolution standards. It features a higher data rate, lower delay, and a packet-optimized system that supports multiple radio access technologies. The EPS includes an EPC network (Evolved Packet Core) and an eRAN (Evolved Radio Access Network).
The LTE network has a flat architecture, which has the following characteristics:
1. The RNC is removed from the radio access network. The only NE in the radio access network is the NodeB.
2. The MSC Server and MGW are removed from the core network. Voice Services are provided based on IP.
3. The PS domain of the core network adopted an architecture similar to Softswitch. lt separates the control plane from the user plane.
The mobility management entity (MME) stores UE contexts on the control allocates an ID to a UE. The MME also performs functions such as mobility management, authentication, key management, encryption, and integrity protection.
A serving gateway (SGW) provides functions such as paging, information management for a UE in an idle state, mobility management, encryption on the user plane, PDCP, SAE bearer control, and encryption and integrity protection for NAS signaling.
lt is an all-IP network.
The reasons for this design are as follows:
1. Too many network layers make it impossible to meet the requirement for low delay, which is less than 10 ms on the radio network side.
2. The all-IP network has the lowest costs because the VolP technology is already mature.
EPS Network Architecture--2G/3G Co-existence
All the interfaces within the EPC, and those extending to functions outside of the EPC, are denoted by the letter ''S''. These all use the service of IP. Elements supporting LTE operation, apart from MME, S-GW, and PDN-GW, include the HSS, PCRF, and ePDG. The RNC and SGSN may also be involved.
HSS (Home Subscriber Server) is considered to be a “master” database. Although logically it is considered as one entity, the HSS in practice is made up of several physical databases depending on the number of subscribers and redundancy requirements. The HSS holds variables and identities for the support, establishment, and maintenance of calls and sessions made by subscribers.
PCRF (Policy and Charging Rules Function) Supports functionality for policy control and charging control. As such, it provides bearer network control in terms of QoS and the allocation of the associated charging vectors.
ePDG (evolved Packet Data Gateway) is used when connecting to Untrusted Non-3GPP IP Access networks. It provides functionality to allocate IP addresses in addition to encapsulating/ decapsulating IPsec and PMIP tunnels.
UE Related Information
Functions of E-UTRAN
The eNodeB hosts the following functions:
Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UES in both uplink and downlink (scheduling).
IP header compression and encryption of user data stream.
Selection of an MME at UE attachment when no routing to an MME can be determined from the information provided by the UE.
Routing of User Plane data towards Serving Gateway.
Scheduling and transmission of paging messages (originated from the MME).
Scheduling and transmission of broadcast information (originated from the MMEor O&M).
Measurement and measurement reporting configuration for mobility and scheduling.
Scheduling and transmission of PWS (which includes ETFs and CMAS) messages (originated from the MME).
Functions of EPC Main Elements
That's the EPS structure I share, and you're welcome to read and learn.
I'll share the E-UTRAN protocol stack structure in the next post.
