Delivered Quality of Service

Description

Delivered QoS (Delivered Quality of Service) is a 3GPP concept that describes the actual QoS parameter values with which content or a service was delivered over the lifetime of a QoS session. Unlike requested or negotiated QoS, which describes the target or agreed service characteristics before or during session setup, Delivered QoS captures the measured, real-world performance that the network actually provided to the end user or application. It is defined in specifications such as TS 21.905 (Vocabulary for 3GPP specifications) and TS 23.057, and is closely related to the QoS framework in TS 23.107.

The concept is central to QoS monitoring and enforcement in mobile networks. When a session is established, an application or user may negotiate a certain QoS profile — for example, a guaranteed bit rate, a maximum delay, or a particular traffic class. However, factors such as radio conditions, network congestion, handovers, and scheduling decisions can cause the actual delivered performance to differ from the requested values. Delivered QoS provides a formal way to record and report those actual values over the entire session lifetime, enabling operators and applications to assess whether service level agreements (SLAs) were met.

In practice, Delivered QoS is used in several contexts. For charging and billing, it allows differentiated charging based on what was actually delivered, rather than solely on what was requested or authorized. For network management and optimization, it provides feedback for capacity planning and troubleshooting. For applications such as streaming, conversational voice, or interactive services, it allows adaptation logic to react to the true quality experienced. The measurement may aggregate parameters such as achieved throughput, packet delay, packet loss, and delay variation across the session.

The original Rel-4 definition of Delivered QoS was broad, stating "the measured QoS over the lifetime of a QoS session." The same definition text also included an unrelated entry for "fine grain" concerning Java security permissions, which created ambiguity in the vocabulary. In Rel-5, the definition was rewritten to be more precise: "actual QoS parameter values with which the content was delivered over the lifetime of a QoS session," with a reference to TS 23.107. This change clarified that Delivered QoS is expressed as QoS parameter values, not just an abstract measurement, and anchored it to the established QoS parameter framework.

Delivered QoS should not be confused with the QoS class identifier or the requested QoS profile. It is an observational, after-the-fact characterization of a session. Its primary value lies in closing the loop between QoS negotiation and QoS experience, giving network operators, service providers, and regulators a concrete basis for verification.

Purpose & Motivation

Delivered QoS exists to bridge the gap between the QoS a user or application asks for and the QoS actually experienced. In early packet-switched mobile networks, QoS was often negotiated at session setup based on a requested profile, but there was no standardized vocabulary for describing what was truly delivered over the session's lifetime. This made it difficult to verify SLAs, to bill accurately for premium services, or to diagnose why an application performed poorly.

The introduction of Delivered QoS in Rel-4 provided a formal term for the measured outcome, enabling consistent reporting and comparison across network elements. Its refinement in Rel-5 tied it explicitly to QoS parameter values and to the QoS framework in TS 23.107, which defines parameters such as traffic class, guaranteed bit rate, maximum bit rate, transfer delay, and traffic handling priority. This made Delivered QoS actionable: it could be expressed in the same units and parameters used for negotiation.

Motivation also came from charging and regulatory requirements. Operators needed to demonstrate that users received the quality they paid for, and regulators needed a way to assess whether advertised service levels were met. By standardizing the vocabulary, 3GPP allowed charging systems, performance management systems, and application clients to share a common understanding of delivered quality, supporting differentiation, accountability, and optimization across generations of mobile networks.