QoS Class Identifier and Quality of Service in LTE Networks

In LTE networks, Quality of Service (QoS) is crucial for ensuring that different types of traffic are treated fairly and efficiently. This is where the QoS Class Identifier (QCI) comes in, which helps determine the QoS characteristics of a particular flow.

The QCI is a 6-bit identifier that is assigned to each flow in an LTE network. It is used to determine the QoS characteristics of the flow, such as its latency, jitter, and packet loss.

Each QCI has a specific set of QoS parameters associated with it, which are used to prioritize and manage the flow. For example, QCI 1 is used for the "GSM VoIP" flow, which has a maximum latency of 100 ms and a maximum jitter of 50 ms.

There are eight predefined QCIs in LTE networks, each with its own set of QoS parameters. These QCIs are used to ensure that different types of traffic, such as voice, video, and data, are treated fairly and efficiently.

Here's an interesting read: Service Set Identifier

The QoS Class Identifier (QCI) mechanism is a class-based system used in LTE networks to assign a scalar value to each carrier type. This value, known as the QCI, is used as a reference to node-specific parameters that control packet forwarding treatment.

Each QCI is assigned one of nine standardized characteristics, including scheduling priority, resource type, packet delay budget, and packet error loss rate. These characteristics are defined by the 3GPP standard and are used to ensure that applications/services mapped to a given QCI receive the same level of QoS in multi-vendor environments as well as in roaming scenarios.

The QCI is mapped to transport network layer parameters in the relevant Evolved Packet Core (EPC) core network nodes, such as the PDN Gateway (P-GW), Mobility Management Entity (MME), and Policy and Charging Rules Function (PCRF). This mapping is done using preconfigured QCI to Differentiated Services Code Point (DSCP) mapping.

Here is a list of the standardized characteristics associated with each QCI:

The priority level of each QCI is also standardized, with Priority level 0.5 being the highest. If congestion is encountered, the lowest Priority level traffic (highest Priority number) would be the first to be discarded.

Observed QCI values can vary depending on the carrier and plan.

On AT&T's Unlimited Starter plan, a QCI of 9 has been observed for regular data use. I'm not sure what this means for my own data usage, but it's worth noting that this QCI value is associated with relatively high-priority data.

On AT&T's Unlimited Extra plan, a QCI of 8 has been observed for regular data use after the allotted Premium Data is used up. I expect a similar transition occurs for subscribers on the Unlimited Elite plan.

A QCI of 9 has also been observed on an unknown plan by Reddit user u/uwroomitup in 2022.

Here are some observed QCI values for different plans:

It's worth noting that PureTalk has a QCI of 8.

QCI in LTE Networks is used to identify the Quality of Service (QoS) class of a specific service. There are two types of QCI classes: GBR (Guaranteed Bit Rate) and Non-GBR. GBR classes guarantee a specific data rate, while Non-GBR classes do not.

GBR classes have a higher priority than Non-GBR classes, with a priority level ranging from 0.7 to 5.5. For example, QCI 65 has a priority level of 0.7, while QCI 5 has a priority level of 1. The packet delay budget for GBR classes is typically between 50 and 300 milliseconds.

Here is a list of some common services associated with each QCI class:

The PERL (Packet Error Loss Rate) for GBR classes is typically 10, which means that up to 10% of packets can be lost without affecting the service. However, for Non-GBR classes, the PERL can be higher, up to 10^, depending on the specific service requirements.

Quality Indicators in LTE Networks are crucial for ensuring a seamless user experience. Quality of Service (QoS) is achieved through the use of QCI, which stands for Quality of Service Class Identifier.

There are 9 classes of QCI, each with its own set of characteristics. These characteristics include the type of resource, priority level, packet delay budget, packet error loss rate, and example services.

The 9 classes of QCI are:

The packet delay budget is the maximum time allowed for a packet to be delivered, and the packet error loss rate is a measure of how reliable the transmission is. The priority level determines the importance of the service, with lower numbers indicating higher priority.

T-Mobile's network prioritizes data use differently depending on the plan.

T-Mobile's Unlimited Intro and Unlimited Plus plans both use QCI 9 for data use.

The Unlimited Premium plan and By-the-gig plans use QCI 8.

Here's a list of T-Mobile plans and their corresponding QCI values:

Verizon's QCI values are based on data usage and Premium Data allowance.

On the Play More Unlimited plan, a QCI of 8 was found for regular data use on July 2, 2020, with Premium Data still available.

After using up Premium Data, a QCI of 9 was found on July 3, 2020.

The Do More Unlimited plan also showed a QCI of 8 for regular data use on September 2, 2020, with Premium Data available.

Verizon's Get More Unlimited plan had a QCI of 8 for regular data use on October 21, 2020, with Premium Data available.

For your interest: How to Use Classes in Webflow Code Embed

When using QoS class identifiers, carriers have specific requirements to ensure efficient network management.

AT&T, for example, uses a 3-bit QCI value, with a default value of 000. This value allows for a high-priority service with guaranteed bit rates.

Verizon Wireless, on the other hand, uses a 4-bit QCI value, with a default value of 0000. This value also supports high-priority services with guaranteed bit rates.

T-Mobile uses a 3-bit QCI value, with a default value of 001. This value prioritizes services with a guaranteed bit rate.

These carrier-specific requirements can impact the choice of QoS class identifier.

Worth a look: High Power User Equipment

There are 80 QCI values in total, ranging from 1 to 80.

The QCI values are categorized into two main types: Guaranteed Bit Rate (GBR) and Non-GBR.

GBR QCI values are used for services that require a guaranteed minimum data rate, such as conversational voice and real-time gaming.

QCI values 1 to 4 are used for GBR services, with QCI 1 having the highest priority level of 2 and a packet delay budget of 100 ms.

Conversational voice services use QCI 1, which has a priority level of 2 and a packet delay budget of 100 ms.

Real-time gaming services use QCI 3, which has a priority level of 3 and a packet delay budget of 50 ms.

Non-GBR QCI values are used for services that do not require a guaranteed minimum data rate, such as video streaming and TCP-based services.

QCI values 5 to 9 are used for Non-GBR services, with QCI 5 having a priority level of 1 and a packet delay budget of 100 ms.

Video streaming services use QCI 6, which has a priority level of 6 and a packet delay budget of 300 ms.

TCP-based services use QCI 6, which has a priority level of 6 and a packet delay budget of 300 ms.

Mission Critical services use specific QCI values, such as QCI 65 for Mission Critical user plane Push To Talk voice.

Here is a summary of some key QCI values:

These QCI values provide a standardized way to classify services and ensure that they receive the necessary network resources to function properly.