4g Lte Evolved Packet Core Epc Concepts And Call Flows Download Hot ^new^ -

Demystifying the 4G LTE Evolved Packet Core (EPC): Concepts and Call Flows

Date: October 26, 2023
Author: Telecom Insights
Category: LTE Technology

How streaming, gaming, and social media actually work under the hood – for tech enthusiasts, students, and entertainment lovers. Demystifying the 4G LTE Evolved Packet Core (EPC):

UE registers with IMS (SIP REGISTER) over default bearer.
IMS authentication/registration interacts with HSS for user profile.
For an outgoing call, IMS INVITE triggers QoS request to PCRF.
PCRF instructs P-GW to create dedicated GBR bearers for RTP/RTCP flows.
SIP signaling establishes media path; RTP flows use dedicated bearers with low latency.
Call termination releases dedicated bearers via PCRF-triggered bearer tear-down.

Role: The "Database."
Functions:
- Contains subscriber profiles (IMSI, subscribed services, QoS).
- Generates authentication vectors (Security keys).
- Works closely with the MME for authentication.

Mobility Management Entity (MME): Control-plane node handling signaling for mobility, authentication, bearer management, paging, and NAS security. Interfaces: S1-MME (to eNodeB), S6a (to HSS), S10 (to other MMEs).
Serving Gateway (S-GW): Anchor point for user plane data during intra-LTE mobility and handovers; routes and forwards user data packets between eNodeB and PDN Gateway. Interfaces: S1-U (to eNodeB), S5/S8 (to P-GW), S11 (to MME for bearer management).
PDN Gateway (P-GW): Connects EPC to external PDNs (e.g., Internet); assigns IP addresses to UEs, enforces policy and charging rules, and performs packet filtering, QoS enforcement, and lawful interception. Interfaces: SGi (to PDN), S5/S8 (to S-GW), Gx (to PCRF).
Home Subscriber Server (HSS): Central subscriber database storing user profiles, authentication data, subscription info, and location-related information. Interfaces: S6a (to MME), Sh (to Application Servers).
Policy and Charging Rules Function (PCRF): Makes real-time policy decisions for QoS and charging; communicates rules to P-GW via Gx.
eNodeB (eNB): LTE base station handling radio interface, scheduling, RRC signaling, and S1 interfaces toward EPC (S1-MME for control, S1-U for user plane).
Optional: IMS (IP Multimedia Subsystem): Provides voice and multimedia services over IP; interfaces with EPC via P-GW and policy elements.