5G Deployment Options (NSA vs SA)

The Problem

You can’t just rip out your entire 4G network and replace it overnight. That would cost billions and leave customers without service.

Two approaches:

1. Non-Standalone (NSA) - Use existing 4G infrastructure, add 5G on top
2. Standalone (SA) - Build a completely new 5G network from scratch

Non-Standalone (NSA)

The idea: Keep your 4G core network, just add 5G radio towers.

• Phone connects to both 4G and 5G simultaneously
• 4G handles the “control” stuff (authentication, mobility)
• 5G provides the fast data

Pros:

• Faster to deploy
• Cheaper
• Uses existing infrastructure

Cons:

• Can’t get full 5G benefits
• Still limited by 4G core

NSA is a stepping stone. Get 5G speeds now, upgrade the core later.

Standalone (SA)

The idea: Build everything fresh - new 5G core, new 5G radios.

• Phone connects to 5G only
• Full 5G core with all new features (network slicing, ultra-low latency)
• No 4G dependency

Pros:

• Full 5G capabilities
• Network slicing works properly
• Future-proof

Cons:

• Expensive
• Takes longer to deploy

SA is the end goal. This is real 5G with all the features.

The Deployment Options

3GPP defined specific “options” numbered by architecture:

EPC = Evolved Packet Core (the 4G core network)

5GC = 5G Core (the new 5G core network with SBA)

LTE = 4G radio access

NR = New Radio (5G radio access)

The Key Options

Option 3 (NSA with 4G core)

• Most common first deployment
• 4G anchor + 5G for speed boost
• Quick to market

Option 2 (Standalone)

• True 5G, no 4G dependency
• Full 5GC with all features
• The ultimate goal

The Migration Path

Most carriers follow this path:

$\text{Option 1} \rightarrow \text{Option 3} \rightarrow \text{Option 2}$

This lets carriers offer “5G” quickly while building out the full 5G core in the background.

Why Option 3 First?

Speed to market matters. Carriers wanted to say “we have 5G” as soon as possible.

Summary