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Word Salad: Disambiguating Quality Terminology
By: ,
02 May 2018

QoS and QoE

QoS, QoE, Network Performance,… What are You Talking About?

Technical literature is often riddled with buzzwords and specialized lingo that can be confusing to understand. In this post, we clarify what it means when we talk about QoS, QoE, and more, to help our readers better navigate these buzzword-laden waters.

Definitions are Good, But Sometimes Not Needed

There are actually standardized definitions for many of the terms we commonly use in relation to quality. For example, in networking, the IETF defines Quality of Service as:

The mechanisms that enable traffic prioritization or resource reservation.

Alternatively, the ITU-T defines Quality of Service (QoS) as:

The totality of characteristics of a telecommunications service that bear on its ability to satisfy stated and implied needs of the user of the service.

At, we use the term QoS with the IETF meaning, which is commonly used in the networking architectures community. Specifically, QoS as mechanisms and architectures to improve the performance of a network, such as Differentiated Services (DiffServ). This is more specific, but still very much related to the definition. Incidentally, when we want to talk about how a network performs, we usually talk about network performance metrics.

The other commonly used meaning for QoS comes from the domain of performance evaluation, and refers, not surprisingly, to the performance of the network. You may often read about networks with “bad QoS”, meaning they had poor performance (for example, low bandwidth, high loss rates, excessive latency, etc.).

Likewise, Quality of Experience (QoE) is another term that is often (ab)used in technical lingo. According to the ITU-T’s definition and the Qualinet white paper that inspired it, Qualinet White Paper on Definitions
of Quality of Experience
, QoE is:

The degree of delight or annoyance of the user of an application or service.

At, when we talk about QoE, we refer to this, as this is the official definition. However, it is most commonly used to talk about perceived quality, which refers to only one aspect of QoE, specifically the perceptual aspects of quality (For example, is the speech intelligible? Is it noisy? Are there artifacts in the video stream?).

In some other cases, QoE is used simply as a buzzword. In reality, people are talking about network performance, or some design characteristics that are expected to improve the perceived quality of the service.

Interestingly, QoE is intimately related to QoS (in all of the meanings mentioned above), as network performance and QoS architectures have a very important role in how users experience the services they use.

In the End, It’s All About Being Clear

At, we believe that when communicating, in particular with our customers, being clear is of paramount importance. When dealing with inherently fuzzy or often confused terms, it is even more so.

I hope this post will help you better navigate quality-related lingo, and more importantly, separate the wheat from the chaff and focus on what’s most important for your interests and product.

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