LTE EPC

Evolved Packet Core (EPC) is a network architecture for 4G LTE that combines voice and data onto an all-IP network, replacing older circuit-switched technologies for voice. 

It handles functions like authentication, session management, and setting up bearers, while also applying Quality of Service (QoS) parameters based on a subscriber's plan. The EPC's framework provides a more efficient, flat architecture that can also support other access networks like 2G, 3G, and Wi-Fi. 

1. Key functions:

• Authentication: Verifies a user's identity and rights to access the network.
• Session management: Manages the state of a user's connection and data sessions.
• Bearer setup: Establishes and manages the dedicated "bearer" channels that carry data traffic.
• Quality of Service (QoS): Applies rules to prioritize and manage different types of traffic (e.g., voice vs. video) based on the user's subscription and policy.

2. Key components:

• Mobility Management Entity (MME): Manages authentication and tracks users across the network.
• Serving Gateway (S-GW): Routes and forwards user data packets between the base station and the Packet Gateway.
• Packet Gateway (P-GW): Connects the EPC to external packet data networks, like the internet, and assigns IP addresses.
• Home Subscriber Server (HSS): Stores all user subscription and profile information.
• Policy and Charging Rules Function (PCRF): Enforces QoS rules and policies for charging.

3. Evolution:

• The EPC is the core network for 4G LTE networks.
• It evolved into the 5G Core (5GC), which is the central component of 5G architecture and offers enhanced capabilities like network slicing and cloud-native design.
• The ability to support both 4G and 5G shows its importance as a transitional and foundational technology.

The evolution from the 4G Evolved Packet Core (EPC) to the 5G Core (5GC) represents a fundamental shift from a hardware-centric, flatter architecture (EPC) to a cloud-native, Service-Based Architecture (SBA) (5GC), enabling advanced 5G features like network slicing, massive IoT support, and ultra-low latency for diverse applications, while Non-Standalone (NSA) deployments allow for gradual transition using the existing EPC with 5G radio. 

1. Key Differences & Evolution: 

• From EPC to 5GC: The EPC (4G) was optimized for mobile broadband, while the 5GC (5G) is designed for flexibility, scalability, and diverse services, using containerized microservices for independent function scaling.
• Architecture: EPC used point-to-point connections with physical elements, whereas 5GC uses a Service-Based Architecture (SBA) with software-defined, modular Network Functions (NFs).
• Cloud-Native: 5GC embraces IT principles like containerization, allowing for dynamic resource allocation, automation, and greater agility compared to the EPC's more rigid structure.
• Functional Separation: 5GC separates control and user planes more efficiently, with functions like AMF (Access and Mobility Management Function) and SMF (Session Management Function) replacing EPC's MME and SGW/PGW, improving scaling and performance.

2. Transitional Importance:

• Non-Standalone (NSA) 5G: Operators initially deploy 5G Non-Standalone (NSA), using the 5G radio with the existing 4G EPC, allowing for incremental upgrades.
• Standalone (SA) 5G: The eventual goal is Standalone (SA) 5G, where 5G New Radios connect directly to the full 5GC, realizing the technology's full potential.
• Dual-Mode Core: Many solutions offer a dual-mode core, running both EPC and 5GC on a common platform, facilitating a smooth migration and maximizing infrastructure use.

This evolution supports new use cases like enhanced mobile broadband (eMBB), massive IoT, and ultra-reliable low-latency communication (URLLC), making the 5GC foundational for future network advancements.