Authorised Quality of Service

Description

Authorised QoS is a fundamental concept in 3GPP policy and charging control (PCC) architecture, introduced in Release 7 as part of the evolved packet system (EPS) to enable differentiated treatment of service data flows. It represents the maximum quality of service that the network authorises for a particular service data flow, based on subscription information, operator policies, and application requirements. The Authorised QoS is determined by the Policy and Charging Rules Function (PCRF) in EPS or the Policy Control Function (PCF) in 5G, and is enforced by the Policy and Charging Enforcement Function (PCEF) or User Plane Function (UPF).

The Authorised QoS contains two key parameters: the QoS Class Identifier (QCI) in 4G or 5G QoS Identifier (5QI) in 5G, and the data rate parameters such as Guaranteed Bit Rate (GBR) and Maximum Bit Rate (MBR). The QCI/5QI defines the packet forwarding treatment in terms of priority, packet delay budget, packet error loss rate, and other characteristics. The data rate parameters specify the bandwidth limits for the flow. When multiple service data flows are aggregated within a single IP-CAN bearer (e.g., a PDP context in GPRS or an EPS bearer in LTE), the Authorised QoS for the bearer is derived by combining the Authorised QoS of the individual flows, typically taking the maximum of the QoS parameters to ensure that the bearer can support the most demanding flow.

In the 5G System (5GS), the concept evolved to operate at the QoS Flow level rather than the IP-CAN bearer level. A QoS Flow is the finest granularity of QoS treatment in 5G, and multiple service data flows can be mapped to the same QoS Flow. The Authorised QoS for a QoS Flow is the combination of the Authorised QoS of the individual service data flows mapped to it. This allows for more flexible and efficient QoS management, as flows with similar QoS requirements can share the same QoS Flow, reducing signalling overhead and resource consumption.

The Authorised QoS is communicated from the PCRF/PCF to the PCEF/UPF via the Gx interface (in 4G) or the N7 interface (in 5G) using Diameter or HTTP/2 protocols. The PCEF/UPF then enforces these parameters by configuring the bearer or QoS Flow accordingly. The Authorised QoS is also used by the PCRF/PCF to make policy decisions, such as whether to allow or deny a service data flow request, and to perform charging and usage monitoring.

Overall, Authorised QoS is a critical enabler for network operators to control and monetise the quality of service experienced by users, ensuring that premium services receive appropriate treatment while preventing abuse and ensuring fair usage of network resources. It is a key component of the 3GPP QoS framework, which has evolved from the bearer-centric model in 4G to the flow-based model in 5G, supporting the diverse requirements of enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC).

Purpose & Motivation

Authorised QoS exists to provide a standardised mechanism for network operators to control the maximum quality of service that can be granted to a service data flow. It solves the problem of resource contention and ensures that the network can enforce policy decisions based on subscription, operator preferences, and application requirements. Without Authorised QoS, the network would lack a unified way to limit and manage the QoS of individual flows, leading to potential abuse, unfair resource allocation, and inability to guarantee service level agreements (SLAs).

Historically, before the introduction of PCC in Release 7, QoS control was more static and less granular. The Authorised QoS concept was introduced to enable dynamic policy control and charging, allowing operators to differentiate services and charge accordingly. It addresses the limitations of earlier approaches where QoS was largely determined by the bearer type and not easily adjustable per flow. With the evolution to 5G, the concept was adapted to QoS Flows to support the new service-based architecture and the need for more flexible QoS handling.

The Authorised QoS also plays a crucial role in enabling new business models, such as sponsored data, where third-party applications can request specific QoS treatment, and network slicing, where different slices can have different QoS policies. It provides the foundation for end-to-end QoS management across multiple access technologies and core networks.