What Are the LTE QCI Classes?
I’ll explain you what QCI classes are in LTE and how they impact your network experience. QCI stands for QoS Class Identifier, and it defines how different types of traffic are treated in the LTE network. Each QCI value is mapped to a specific set of characteristics like priority, delay tolerance, and acceptable packet loss.
Let me walk you through the different QCI classes so you understand how LTE handles voice, video, browsing, and background traffic differently.
LTE QCI Class Overview
| QCI | Typical Service | Priority Level | Packet Delay Budget (ms) | Packet Loss Rate |
|---|---|---|---|---|
| 1 | VoIP (IMS voice) | 2 | 100 | 10-2 |
| 2 | Live video (conversational) | 4 | 150 | 10-3 |
| 3 | Real-time gaming | 3 | 50 | 10-3 |
| 4 | Video streaming (buffered) | 5 | 300 | 10-6 |
| 5 | Default bearer for internet | 9 | 300 | 10-6 |
| 6 | IMS signaling | 6 | 100 | 10-6 |
| 7 | Video (live streaming) | 7 | 100 | 10-3 |
| 8 | Background traffic (email, updates) | 8 | 300 | 10-6 |
| 9 | Background traffic | 9 | 300 | 10-6 |
Here’s how you can think of it — higher priority QCIs like 1 or 2 are for delay-sensitive services like voice or video calls, where low latency and minimal loss are critical. Lower priority QCIs like 8 or 9 are for background tasks, where a small delay is acceptable.
So when you’re making a VoIP call or streaming a live video, LTE uses these QCI classes to allocate resources and maintain service quality in real-time. It ensures your critical apps perform smoothly even when the network is busy.