Quality of experience
||It has been suggested that this article be merged into User experience. (Discuss) Proposed since April 2011.|
Quality of Experience (QoE or simply QX) is a subjective measure of a customer's experiences with a service (web browsing, phone call, TV broadcast, call to a Call Center). QX focuses on the entire service experience, and is a more holistic evaluation than the more narrowly focused UX (user experience, focused on a software interface) and CX (customer experience, support focused).
Quality of Experience systems will try to measure metrics that customer will directly perceive as a quality parameter (in example : time for a new channel to be played when changing channel on TV). It looks at a vendor's or purveyor's offering from the standpoint of the customer or end user, and asks, "What mix of goods, services, and support, do you think will provide you with the perception that the total product is providing you with the experience you desired and/or expected?" It then asks, "Is this what the vendor/purveyor has actually provided?" If not, "What changes need to be made to enhance your total experience?" In short,QoE provides an assessment of human expectations, feelings, perceptions, cognition and satisfaction with respect to a particular product, service or application.
It is related to but differs from Quality of Service (QoS), which attempts to objectively measure the service delivered by the vendor, with QoS measurement is most of the time not related to customer, but to media (customers will never tell you : the jitter is too high). It is tied closely to the black and white of a contract and measures how well the vendor lives up to its end of the bargain. As to the relationship between QoS and QoE and the application of QoE in Communications Ecosystem see
A vendor/purveyor may be living up to the terms of a contract's language, thus rating high in QoS, but, the users may be very unhappy, thus causing a low QoE. Conversely, the users may be very happy with a product or a vendor, resulting in an artificially high QoE if the vendor is not, in fact, doing what he was paid to do, thus rating low in QoS.
Quality of experience (QoE) is a fast emerging multidisciplinary field based on social psychology, cognitive science, economics, and engineering science, focused on understanding overall human quality requirements. QoE is the blueprint of all human quality needs and expectations. Traditionally,technology-centric approaches based on quality of service (QoS) parameters have been employed to ensure service quality to end users. QoE expands this horizon to capture people’s aesthetic and even hedonic needs. QoE is a blueprint of all human subjective and objective quality needs and experiences arising from the interaction of a person with technology and with business entities in a particular context.
Toward Total Quality of Experience:A QoE Model in a Communication Ecosystem.
In medical terminology QoE is also known as "Quality of Patient Experience," and is a subjective measure of a patient's experiences with a medical practice. It looks at a care provider's offering from the standpoint of the patient's holistic experience, and asks, "How did patient fare after the treatment was concluded over an extended period of time? Did they enjoy a higher, similar, or lower quality of life after the treatment? For how long? How did this patient's quality of life, post-treatment compare with other patients who received similar treatment" And then asks, "What changes need to be made to the treatment to enhance the patient's quality of life?"
QoE in the context of telecommunications networks (here more recently also abbreviated as QoX) is a purely subjective measure from the user’s perspective of the overall value of the service provided. That is to mean, QoE cannot be taken a simply the effective quality of the service but must also take into consideration every factor that contributes to overall user value such as suitableness, flexibility, mobility, security, cost, personalization and choice.
Apart from its being user dependent, it will invariably be influenced by the user’s terminal device (for example Low Definition or High Definition TV), his environment (in the car or at home), his expectations (cellular or corded telephone), the nature of the content and its importance (a simple yes/no message or an orchestral concert). Mean Opinion Score (MOS) used for assessing the quality of telephone connections is a limited form of QoE measurement process, relating to a specific media type, in a controlled environment and without specific user expectations. MOS has been expanded to assess the quality of television over ADSL (IPTV), by judging jittering, blockiness and artefacts of a viewed video signal.
Although QoE is perceived as subjective, it is the only measure that counts for customers of a service. Being able to measure it in a controlled manner helps operators understand what may be wrong with their services.
The only way to know how customers see your business is to look at it through their eyes.
— Daniel R. Scoggin, Founder T.G.I.Friday's, Inc.
Engineering Processes and QoE
As an important measure of the end-to-end performance at the services level from the user's perspective the QoE is an important metric for the design of systems and engineering processes. This is particularly relevant for video services because bad network performance may highly affect the user's experience, mainly because these services are compressed and have low entropy. So, when designing systems the expected output, i.e. the expected QoE, is often taken into account also as a system output metric.
This QoE metric is often measured at the end devices and can conceptually be seen as the remaining quality after the distortion introduced during the preparation of the content and the delivery through the network until it reaches the decoder at the end device. There are several elements in the video preparation and delivery chain and some of them may introduce distortion. This causes the degradation of the content and several elements in this chain can be considered as "QoE relevant" for video services. These are the encoding system, transport network, access network, home network and end device.
The concept of QoE in engineering is also known as Perceived Quality of Service (PQoS), in the sense of the QoS as it is finally perceived by the end-user. The evaluation of the PQoS for audiovisual content will provide a user with a range of potential choices, covering the possibilities of low, medium or high quality levels. Moreover the PQoS evaluation gives the service provider and network operator the capability to minimize the storage and network resources by allocating only the resources that are sufficient to maintain a specific level of user satisfaction.
Another approach for measuring QoE in Video content is using a referenceless analysis. In this case, the QoE is not measure comparing an original video to delivered one, but by trying to detect artifacts such as blockiness, blur or jerkiness directly in the video. This approach is based on the idea that customers don't know the original content.
The evaluation of the PQoS is a matter of objective and subjective evaluation procedures, each time taking place after the encoding process (post-encoding evaluation). Subjective quality evaluation processes (PQoS evaluation) require large amount of human resources, establishing it as a time-consuming process. Objective evaluation methods, on the other hand, can provide PQoS evaluation results faster, but require large amount of machine resources and sophisticated apparatus configurations. Towards this, objective evaluation methods are based and make use of multiple metrics.
Example : PQoS for a web site.
- Perimeter (EU Project)
- ICT Action COST IC1003: European Network on Quality of Experience in Multimedia Systems and Services (QUALINET)
- QoMEX - Workshop on Quality of Multimedia Experience