In the context of 5G, “NSA” and “SA” refer to two deployment architectures, each representing a different approach to the implementation of the 5th generation of mobile networks. These terms stand for “Non-Standalone” (NSA) and “Standalone” (SA). They describe how 5G networks are initially deployed and evolved. Here are the key details about NSA and SA in 5G:
NSA (Non-Standalone):
- Definition:
- Initial Deployment: NSA refers to the deployment architecture where 5G radio access is introduced while relying on the existing 4G LTE core network for certain essential functions.
- Key Characteristics:
- Interdependence with LTE: In NSA, 5G NR (New Radio) operates alongside the existing LTE infrastructure. The 5G radio access network (gNB) and LTE evolved NodeB (eNB) work together to provide connectivity.
- Control Plane Anchor: The control plane functions, such as signaling and management, are anchored in the LTE core network. The 5G radio access is used for user plane data transmission.
- Benefits:
- Faster Deployment: NSA allows for a faster deployment of 5G services as it leverages the existing LTE core. Operators can introduce 5G capabilities to users more quickly.
- Optimizing Existing Infrastructure: It enables operators to optimize their existing LTE infrastructure while gradually transitioning to a full 5G core.
- Evolution Path:
- Intermediate Step: NSA is considered an intermediate step in the evolution towards a fully standalone 5G architecture. It provides a pragmatic approach to introducing 5G services without a complete overhaul of the core network.
- Use Cases:
- Enhanced Mobile Broadband (eMBB): NSA is well-suited for scenarios where the primary focus is on delivering enhanced mobile broadband services with higher data rates.
SA (Standalone):
- Definition:
- Complete 5G Core: SA refers to the deployment architecture where both the 5G radio access and the core network are built from scratch as part of the 5G architecture.
- Key Characteristics:
- Independence from LTE: In SA, 5G NR operates independently without relying on LTE infrastructure. Both the control plane and user plane functions are handled by the 5G core network.
- Benefits:
- Full 5G Capabilities: SA allows for the realization of the full capabilities of 5G, including advanced features like network slicing, ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC).
- Optimized Architecture: SA is optimized for the unique requirements of 5G, providing a more efficient and scalable architecture compared to NSA.
- Evolution Path:
- Long-Term Vision: SA represents the long-term vision for 5G networks, offering a complete and standalone architecture that fully leverages the potential of the 5G core.
- Use Cases:
- URLLC and mMTC: SA is particularly suitable for use cases that demand ultra-reliable low-latency communications (URLLC) and massive machine-type communications (mMTC), beyond the capabilities of LTE.
Coexistence and Transition:
- Interworking:
- Transition Period: During the transition from NSA to SA, both architectures may coexist. Operators can maintain compatibility with existing LTE networks while gradually migrating to a standalone 5G core.
- Backward Compatibility:
- User Devices: User devices are designed to support both NSA and SA modes, ensuring backward compatibility with LTE and facilitating a smooth transition.
- Deployment Strategies:
- Operator Choice: Operators can choose deployment strategies based on their network evolution plans, market demands, and available resources. The choice between NSA and SA depends on factors such as deployment speed, network optimization, and the desire to leverage advanced 5G core features.
In summary, NSA and SA represent two deployment architectures for 5G, each with its own advantages and use cases. NSA provides a faster path to 5G deployment by leveraging the existing LTE core, while SA offers the complete and optimized capabilities of 5G with a standalone core network. The coexistence of both architectures allows for a flexible and gradual transition to the full potential of 5G networks.