What is QCI 1 and 9 in LTE?
In this article, we will dive into the concepts of QCI (QoS Class Identifier) 1 and QCI 9 in LTE networks, which are essential for ensuring the quality of service (QoS) for different types of traffic. QoS is an important aspect of LTE, as it determines how traffic is prioritized and handled by the network, ensuring that real-time services, like voice or video calls, receive the best possible treatment.
Let’s first understand what QCI is. In LTE, QCI is used to define the QoS for different types of traffic. It is a number that represents a specific level of service quality in terms of latency, throughput, and packet loss. The lower the QCI value, the higher the priority the traffic will receive, ensuring better performance for that traffic type.
QCI 1 is the highest priority class used in LTE networks. It is primarily reserved for applications that require the highest level of service, such as voice services (VoLTE). When a user makes a voice call over LTE, it is assigned QCI 1, which guarantees minimal latency, low packet loss, and high reliability, providing the best possible experience for real-time communication. Since voice traffic is time-sensitive, QCI 1 ensures that the voice packets are given priority over other less critical traffic types.
On the other hand, QCI 9 is a lower priority class used for less time-sensitive services. QCI 9 is typically used for background traffic or services that are not as sensitive to delays, such as email or web browsing. While QCI 9 ensures that the traffic is delivered, it does not prioritize it as highly as QCI 1. This means that while web pages and emails will be delivered, they may experience delays or be deprioritized in favor of higher-priority traffic, especially during periods of network congestion.
Here’s a breakdown of how QCI 1 and QCI 9 are typically used in LTE:
- QCI 1: Used for latency-sensitive applications like VoLTE (Voice over LTE) and video calls. These applications require a guaranteed level of service quality, such as low latency (less than 100ms), minimal packet loss, and high reliability.
- QCI 9: Used for less critical services like web browsing, email, and file downloads. While these services are important, they don’t require the same low-latency and high-priority treatment that QCI 1 services demand.
In terms of QoS parameters, QCI 1 typically offers a target delay of less than 100 milliseconds and allows for very little packet loss. On the other hand, QCI 9 is more lenient in terms of delay and packet loss, with higher latency being acceptable.
Why is this important? By assigning different QCIs to different types of traffic, LTE networks can efficiently allocate resources and manage traffic in a way that ensures the most critical services (like voice and video) get the highest priority and best performance, while less critical services (like email and browsing) are given lower priority without compromising their functionality.
As we’ve learned in previous discussions about LTE QoS, this prioritization helps maintain a smooth user experience across a wide range of services and use cases. The network dynamically adjusts how traffic is handled based on the assigned QCI, ensuring a balanced and efficient operation.