Background: what is QoE and why should a provider work with it

We talk about the main components of QoE and how to determine it. We’ll also discuss how QoE information can help your service provider improve its quality of service.





/ CC BY / Norlando Pobre

What is meant by QoE

There is no single definition for Quality of Experience in the IT industry. But usually QoE is understood as the general satisfaction of customers with the services of an Internet provider.



The quality of perception depends on several factors, both subjective and objective. In the first case, the user's rating is affected by his experience working with other operators. It compares prices, the ratio of technical support and so on.







The main metric of objective QoE factors is Quality of Service (QoS). In this case, the subscriber’s impressions are formed by network performance and stability, the presence / absence of artifacts when watching videos, as well as extraneous clicks and noise in VoIP conversations.

How to measure QoE

Although some of the factors affecting QoE are subjective, the quality of user perception can be measured. A lot of research is going on in this area.

The method of determination depends on the service or service (audio, video, streaming, etc.).



Speech and audio . They use the so-called E-model, which was proposed by the International Telecommunication Union (ITU). She predicts the user experience during a conversation over VoIP, based on the characteristics of the equipment and network parameters. This information is substituted into the formula, the coefficients of which are selected on the basis of a series of subjective experiments.

$$

$$R = R_0-I_s-I_d-I_e + A$$

Here, $$$R_0$ Is the signal to noise ratio, $$$I_s$ - takes into account the volume of speech and the presence of overtones during a conversation, $$$I_d$ - the level of distortion resulting from signal delays, $$$I_e$ - assesses the impact of the used codecs and equipment. Concerning $$$A$ , then this is an allowable decline in QoE quality, with which the client is ready to put up with (for example, in exchange for mobility when connected to Wi-Fi). The exact numerical values ​​for each parameter can be found in the ITU documentation .



Further, the coefficient $$$R$ recounted in Mean Opinion Score (MOS), which represents the average value of the quality of user perception. You can find the formula in the work of engineers on page three .

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Network games . To assess the quality of perception when playing on a computer, a number of providers use the G-model. It was proposed by a group of engineers from the Netherlands Organization for Applied Scientific Research (TNO). It takes into account factors such as latency, jitter, and loss of network connection packets. The formula is as follows:

$$

$$MOS = max (4.33-3.08 ∙ 10 ^ {- 9} X ^ 3 + 1.18 ∙ 10 ^ {- 5} X ^ 2-1.15 ∙ 10 ^ {- 2} X, 1 )$$

Behind parameter $$$X$ The effect of network outages on QoE is hidden. It is calculated as follows:

$$

$$X = min (PING + 0.686 ∙ JITTER, 650)$$

Dutch experts tested the formula on games like Quake IV, Quake III, Unreal Tournament, Counter Strike, and Halo. The accuracy of the method was about 98%.



Video QoE when watching a video is influenced by factors such as brightness and contrast of the picture, color reproduction, the presence of visible distortion and artifacts. Sometimes the quality of perception for a video is measured using a series of subjective tests. Experts watch video clips and evaluate their quality on a five-point scale - then average the results. To eliminate the human factor, they use specialized software such as Video Quality Metric , which finds various artifacts in the video: blur, unnatural image movement, noise.

How do we measure QoE

Evaluate QoE also allows our system. It offers a set of functions for monitoring network equipment and user activity, as well as a system for recording applications and conducting surveys. Here are two metrics that measure perceptual quality:



RTT (round-trip time) . This is the time required to transmit the signal, process it and confirm receipt.





/ RTT Calculation / VAS Experts Webinar Slide on QoE



Retransmit . The system registers repeated data transmission attempts that occur each time the client does not wait for the SYN / ACK response from the server for 10 seconds.



Data on RTT and retransmissions are displayed on dashboards in the form of graphs. The monitoring department can work with these statistics and respond to increased RTT indicators by tracking them visually.





/ RTT Change Charts / VAS Experts Webinar Slide

Why is this an Internet Service Provider

By monitoring connection errors, you can evaluate the overall status of the network. If they are systematic, it is worth making sure that there are no problems with the IT infrastructure.



QoE allows you to solve other problems. Having evaluated RTT and retransmitters, marketers get the opportunity to sell equipment with the best performance and coverage, as well as provide information about the load and quality of the channel through the subscriber’s personal account. Such steps will help raise QoE and reduce potential customer churn.

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