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EPS presentation
The Evolved Packet System (EPS) architecture consists of the E-UTRAN radio network and Evolved Packet Core network. The EPS architecture includes the User Equipment (UE), e-nodeB base stations, Mobility Management Entity (MME), Home Subscriber Server (HSS), Serving Gateway (S-GW), and Packet Data Network Gateway (P-GW). When a UE wants to attach to the network, it sends an attach request to the e-nodeB, which determines the appropriate MME. The MME then authenticates the UE with the HSS and sets up bearers between the e-nodeB, S-GW, and P-GW to complete the attach procedure and allow the UE
EPS presentation
- 1. EVOLVED PACKET SYSTEM(EPS) Architecture & Attach Procedure By Anirudh Yadav
- 2. WHAT IS EPS? • Release 8 of 3GPP • E-UTRAN (Radio N/W) + EPC (Core N/W) = EPS • Flow of EPS architecture. User Radio N/W Core N/W IP N/W (UE, e-nodeB) (E-UTRAN) (EPC) (IMS)
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- 4. Continued….. • UE: refersto the device controlled by user Eg.- mobile, tablet, USB dongle etc. • E-nodeB: – formal name for cell tower. – X2 interface with other e-nodeBs. – WCDMA vs. EPS architecture. • MME: – Keeps track of user state whether ON or OFF – Communicates with HSS for security keys & encrypted data – User can be registered with 1 MME at a time. – Primary responsibilities include EMM (user’s location & state?) & ESM (create actual data session)
- 5. Continued…. • HSS: – Similarto HLR – Contains all encrypted data related to user. – Acts as a database information storage node. • S-GW: – 1 UE can be served by 1 S-GW. – MME tells it what P-GW to connect to. – Handles user IP packets b/w e-nodeB & P-GW. • PDN-GW: – Known as PCEF, connected to PCRF, OCS (billing server) – Controls amount of QoS dictating its services as a DICTATOR. – Functionally an IP router.
- 6. CONTROL & USERPLANE
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- 8. Continued…. 1. ATTACH REQUEST: –UE wants to connect, sends an attach request to e-nodeB – E-nodeB determines which MME to connect to. 2. AUTHENTICATION INFO REQUEST/RESPONSE – MME queries the HSS for key information – Pre-shared key concept – MME asks e-nodeB what specific it wants to ask? – Authentication successful. 3. UPDATE LOCATION REQUEST – HSS declares specific MME for the UE – In case of old MME it cancels it & update the location register.
- 9. Continued…. 4. UPDATE LOCATIONANSWER – HSS forwards the UE’s subscription services, QoS networks & information to the MME. 5. CREATE SESSION REQUEST – MME figures out what P-GW can serve that external network & what S-GW can serve what e-nodeB to which subscriber is connecting on. – Tunnels points/legs get created b/w e-nodeB & S-GW & b/w S-GW & P-GW. 6. CREATE SESSION RESPONSE – P-GW- Dictator, billing with OCS sever, controls QoS settings – MME gets this response from P-GW through S-GW.
- 10. Continued…. 7. ATTACH ACCEPT: –MME sends IP in ATTACH ACCEPT to UE. – Also include IP of S-GW for e-nodeB – E-nodeB forwards ATTACH ACCEPT as part of RRC message. 8. ATTACH COMPLETE – UE sends ATTACH COMPLETE to MME – Connection b/w UE & e-nodeB & b/w S-GW & P-GW gets created. 9. MODIFY BEARER REQUEST – MME sends this request to S-GW – Includes TEID of e-nodeB – Connection b/w e-nodeB & S-GW gets completed – UE is able to exchange data
- 11. HISTORICAL CONTEXT GPRS • MS(Mobile sation) • nodeB • RNC • SGSN • GGSN • HLR EPS • UE • E-nodeB • E-nodeB • S-GW & MME • P-GW • HSS