How Many QCI Classes Are Defined in LTE?
Let me explain the concept of Quality of Service (QoS) Class Identifier (QCI) in LTE. QCI is used to define the service quality for various types of traffic, ensuring that each service gets the appropriate level of priority and network resources. The QCI value helps prioritize traffic based on factors like delay, throughput, and packet loss. This way, critical services like voice calls are given higher priority, while less critical traffic like bulk data transfers may be assigned lower priority.
In LTE, there are 9 QCI classes, each designed to meet the specific needs of different types of services. These classes are numbered from QCI 1 to QCI 9, with lower numbers corresponding to higher priority services. Let’s go over each QCI class and its characteristics:
| QCI Class | Description | Priority & Requirements |
|---|---|---|
| QCI 1 | Conversational Voice | Highest priority, strict delay, and minimal packet loss. Designed for voice calls where real-time communication is critical. |
| QCI 2 | Conversational Video | High priority, low latency. Used for video calls like Skype or FaceTime, where real-time communication and quality are key. |
| QCI 3 | Real-Time Signaling | High priority for signaling traffic, such as SIP messages during VoIP calls, which need to be processed quickly to set up or maintain calls. |
| QCI 4 | Non-Conversational Video | Medium priority, suitable for video streaming services (like Netflix), which can tolerate some delay but still require a good user experience. |
| QCI 5 | Video or Audio Streaming | Medium priority, designed for streaming services where some delay is acceptable but should not affect the user experience significantly. |
| QCI 6 | Interactive Gaming | Medium priority, for interactive gaming applications where low delay and sufficient throughput are required to maintain a smooth experience. |
| QCI 7 | HTTP and Web Browsing | Low priority, used for general web browsing and HTTP traffic, where delay and packet loss can be tolerated more than in real-time services. |
| QCI 8 | Background Traffic (FTP, Email) | Low priority, ideal for services that don’t require low latency, like email or file transfers, where a delay is less of an issue. |
| QCI 9 | Bulk Data (File Transfer, Backup) | Lowest priority, suitable for non-time-sensitive services like cloud backups or large file transfers, where delays are acceptable. |
As you can see, the QCI classes provide a way to ensure that each service gets the network resources it needs based on its requirements. High-priority services like voice (QCI 1) or video calls (QCI 2) get the lowest delay and minimal packet loss, while less urgent services, like bulk data transfers (QCI 9), are assigned lower priority with more tolerance for delays.
This system helps to optimize the overall performance of the network by ensuring that the most important services are given the resources they need to function without interruption, while less critical services can still operate with acceptable performance.