5G RAN WIRELESS NSA Architecture

The 5G RAN (Radio Access Network) NSA (Non-Standalone) Architecture refers to the design of the 5G network that uses a combination of 5G New Radio (NR) and 4G LTE (Long-Term Evolution) infrastructure. In NSA mode, the 5G RAN is integrated with an existing 4G EPC (Evolved Packet Core) network, allowing 5G services to be deployed without requiring a complete overhaul of the existing core network.

Here’s an overview of the key components and architecture of the 5G RAN NSA:

1. 5G New Radio (NR)

• 5G NR is the radio access technology that defines how devices connect to the 5G network. It provides high-speed, low-latency communication and is designed to work alongside existing LTE infrastructure in the NSA architecture.
• The NR operates in two frequency bands:
  • Sub-6 GHz: This includes frequencies below 6 GHz and is used for broader coverage and penetration.
  • Millimeter-Wave (mmWave): Frequencies above 24 GHz used for ultra-high-speed, high-capacity data transfer.

2. 4G LTE Core (Evolved Packet Core – EPC)

• In the NSA architecture, the EPC is used as the core network to handle signaling, mobility, and service management, while 5G NR takes care of the radio access.
• Key components of the EPC include:
  • MME (Mobility Management Entity): Manages signaling, mobility, and security for user equipment (UE).
  • SGW (Serving Gateway): Routes and forwards data packets between eNodeB (4G) and the core network.
  • PGW (Packet Gateway): Connects the EPC to external data networks and the internet.

3. gNB (Next Generation Node B)

• The gNB is the base station in 5G RAN and is responsible for providing the wireless interface to 5G devices. In NSA mode, the gNB works alongside the existing eNodeB (4G LTE base station).
• The gNB has two functional elements:
  • CU (Central Unit): Handles higher-layer functions such as user plane and control plane separation.
  • DU (Distributed Unit): Handles lower-layer functions, such as scheduling and radio resource management.

4. eNodeB (Evolved Node B)

• The eNodeB is the base station for 4G LTE that controls the LTE air interface. It is responsible for functions such as radio resource management, mobility, and user plane data forwarding.
• In NSA, the eNodeB is used for connecting to the 4G LTE core (EPC), while the 5G NR is handled by the gNB.

5. X2 Interface

• The X2 interface is a connection between eNodeBs and is used for inter-eNodeB communication, primarily for handover and load balancing.

6. S1 Interface

• The S1 interface connects the eNodeB with the EPC (MME and SGW). It is used for control plane (signaling) and user plane (data transfer) communication.

7. NG Interface

• The NG interface connects the gNB to the EPC, specifically to the MME (Mobility Management Entity) and the SGW (Serving Gateway). It supports both control plane and user plane signaling for 5G services.

8. Dual Connectivity (EN-DC)

• Dual Connectivity (EN-DC) is a key feature in NSA architecture. It allows a device to simultaneously connect to both 4G LTE (via eNodeB) and 5G NR (via gNB), enabling higher data throughput and seamless handovers.
• This involves Master eNodeB (typically 4G eNodeB) and Secondary gNB (5G NR base station), where the data is split between both network technologies.

9. User Equipment (UE)

• User Equipment (UE) refers to the device that connects to the 5G network, such as a smartphone or IoT device. In NSA architecture, the UE can connect to both 4G LTE and 5G NR networks using Dual Connectivity.

10. Signaling and Data Flow

• Control Plane (Signaling): Signaling between the UE, eNodeB, and gNB is handled through the NG Interface and S1 Interface, which manage the connection, handover, and mobility for the user.
• User Plane (Data Transmission): The data transfer between the UE and the core network passes through the eNodeB or gNB to the EPC.

Summary of 5G RAN NSA Architecture:

• Dual Connectivity (EN-DC): The UE connects to both 4G LTE (eNodeB) and 5G NR (gNB) to provide higher capacity and better service continuity.
• Core Network (EPC): The EPC, which is the core for 4G LTE, is used in NSA mode for signaling, data routing, and management of sessions.
• gNB & eNodeB: The 5G NR (gNB) and 4G LTE (eNodeB) base stations cooperate to provide access and coverage.
• X2 and NG Interfaces: These interfaces are used for communication between the eNodeB and gNB, as well as for interaction with the core network.

In summary, the 5G NSA architecture is designed to bring 5G speeds and benefits to users while leveraging the existing 4G LTE network infrastructure. It allows mobile operators to provide 5G services without needing a full replacement of the existing 4G core network.