QoS Class Identifier (QCI) is a mechanism used in
3GPP Long Term Evolution
In telecommunications, long-term evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA standards. It improves on those standards' capacity and speed by usi ...
(LTE) networks to ensure carrier traffic is allocated appropriate
Quality of Service
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...
(QoS). Different carrier traffic requires different QoS and therefore different QCI values. QCI value 9 is typically used for the default carrier of a UE/PDN for non privileged subscribers.
Background
To ensure that carrier traffic in LTE networks is appropriately handled, a mechanism is needed to classify the different types of carriers into different classes, with each class having appropriate QoS parameters for the traffic type. Examples of the QoS parameters include Guaranteed Bit Rate (GBR) or non-Guaranteed Bit Rate (non-GBR), Priority Handling, Packet Delay Budget and Packet Error Loss rate. This overall mechanism is called QCI.
Mechanism
The QoS concept as used in LTE networks is class-based, where each carrier type is assigned one QoS Class Identifier (QCI) by the network. The QCI is a scalar that is used within the access network (namely the
eNodeB
E-UTRAN Node B, also known as Evolved Node B (abbreviated as eNodeB or eNB), is the element in E-UTRA of LTE that is the evolution of the element Node B in UTRA of UMTS. It is the hardware that is connected to the mobile phone network that commu ...
) as a reference to node specific parameters that control packet forwarding treatment, for example scheduling weight, admission thresholds and link-layer protocol configuration.
The QCI is also mapped to transport network layer parameters in the relevant
Evolved Packet Core
System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.
SAE is the evolution of the GPRS Core Network, but with a simplified architecture; an all-IP ...
(EPC) core network nodes (for example, the
PDN Gateway
System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.
SAE is the evolution of the GPRS Core Network, but with a simplified architecture; an all-IP ...
(P-GW),
Mobility Management Entity
System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.
SAE is the evolution of the GPRS Core Network, but with a simplified architecture; an all-IP ...
(MME) and
Policy and Charging Rules Function
Policy and Charging Rules Function (PCRF) is the software node designated in real-time to determine policy rules in a multimedia network. As a policy tool, the PCRF plays a central role in next-generation networks. Unlike earlier policy engines th ...
(PCRF)), by preconfigured QCI to
Differentiated Services Code Point
Differentiated services or DiffServ is a computer networking architecture that specifies a mechanism for classifying and managing network traffic and providing quality of service (QoS) on modern IP networks. DiffServ can, for example, be used t ...
(DSCP) mapping.
According to 3GPP TS 23.203, 9 QCI values in Rel-8 (13 QCIs Rel-12, 15 QCIs Rel-14) are standardized and associated with QCI characteristics in terms of packet forwarding treatment that the carrier traffic receives edge-to-edge between the
UE and the P-GW. Scheduling priority, resource type, packet delay budget and packet error loss rate are the set of characteristics defined by the 3GPP standard and they should be understood as guidelines for the pre-configuration of node specific parameters 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 characteristics are not signalled on any interface.
The following table illustrates the standardized characteristics as defined in the 3GPP TS 23.203 standard "Policy and Charging Control Architecture".
Every QCI (GBR and Non-GBR) is associated with a Priority level. Priority level 0.5 is the highest Priority level. If congestion is encountered, the lowest Priority level traffic (highest Priority number!) would be the first to be discarded.
QCI-65, QCI-66, QCI-69 and QCI-70 were introduced in 3GPP TS 23.203 Rel-12.
QCI-75 and QCI-79 were introduced in 3GPP TS 23.203 Rel-14.
QCI-67 was introduced in 3GPP TS 23.203 Rel-15.
See also
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LTE
References
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LTE (telecommunication)
Mobile technology