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Wednesday, June 15, 2011

User-Centric Networking Paradigms: From QoS to QoE (Quality of Experience)


Current practices in the telecommunication business still tie the users to a single operator even though the number of players in the market has long been growing. The users tend to manually combine their subscriptions to multiple operators in order to take simultaneous advantage of their different offers that are suited for a variety of services, as illustrated below;

For example, a user might hold two SIM cards/ phones from two distinct operators, one of which provides a flat-rate national calling plan while the other provides low cost, high-quality international calling with pay-as-you-go option. Extending this example to a case where there are a large number of operators with a multitude of service options and offers in future all-IP telecommunication networks, manual handling of such multi-operator service combinations is clearly tedious and impractical for the user.

In its most generic sense, the user-centric view in telecommunications considers that the users are free from subscription to any one network operator and can instead dynamically choose the most suitable transport infrastructure from the available network providers for their terminal and application requirements. In this approach, the decision of interface selection is delegated to the mobile terminal enabling end users to exploit the best available characteristics of different network technologies and network providers, with the objective of increased satisfaction. The generic term satisfaction can be interpreted in different ways, where a natural interpretation would be obtaining a high quality of service (QoS) for the lowest price. In order to more accurately express the user experience in telecommunications, the term QoS has been extended to include more subjective and also application-specific measures beyond traditional technical parameters, giving rise to the quality of experience (QoE) concept. user-centric networking paradigm for future telecommunication networks, where the users not only make network-selection decisions based on their local QoE evaluation but also share their QoE evaluations with each other for increased efficiency and accuracy in network selection, as depicted in below is being developed;
QoE reflects the collective effect of service performances that determines the degree of satisfaction of the end user, e.g., what the user really perceives in terms of usability, accessibility, retainability, and integrity of the service. Until now, seamless communications is mostly based on technical network QoS parameters, but a true end-user view of QoS is needed to link between QoS and QoE. While existing 3GPP or IETF specifications describe procedures for QoS negotiation, signaling, and resource reservation for multimedia applications, such as audio/video communication and multimedia messaging, support for more advanced services, involving interactive applications with diverse and interdependent media components, is not specifically addressed.
Such innovative applications, likely to be offered by third-party application providers and not the operators, include collaborative virtual environments, smart home applications, and networked games. Additionally, although the
QoS parameters required by multimedia applications are well known, no standard QoS specification is enabled to deploy the underlying mechanisms in accordance with the application QoS needs. For future Internet to succeed and to gain wide acceptance of innovative applications and service, not only QoS objectives but also QoEs have to be met. Perceived quality problems might lead to acceptance problems, especially if money is involved. For this reason, the subjective quality perceived by the user has to be linked to the objective, measurable quality, which is expressed in application and network performance parameters resulting in QoE. Feedback between these entities is a prerequisite for covering the user’s perception of quality.
There is no standard yet on evaluating and expressing QoE in a general context. However, there have been recommendation documents or publications that suggest mainly application-specific QoE metrics, objectives, and considerations.

A QoE framework, acting as an enabler for inter-operator mediation is therefore needed to achieve this paradigm. The illustration below shows a middleware framework in which middleware running on the user terminal, which is responsible for acquiring, processing, and exploiting the QoE-related information is used.

In order to make user-centric decisions and share user experiences based on QoE, a software entity must first evaluate and quantify QoE for a given set of inputs including the network interface and the application running on the user terminal. Named as the data network processor (DNP), this entity is responsible for calculating, from network performance measurements, user’s context information, and user’s feedback, a QoE descriptor (QoED). This QoED will be used to take a handover action based on user’s policies. The main responsibility of the DNP is generating QoED reports. Each QoED item is an aggregate and synthetic description of the quality of the user’s experience.

Telecommunication network management practices are strongly rooted in the monopolistic telecom operators. The liberalization of the operators has only changed the landscape in a way that there were multiple closed operators rather than one closed operator. As a result, they are usually centrally managed, poorly integrated with outside components, and strictly isolated from external access. On the other hand, the IP world has been about internetworking from its conception (hence the name IP, Internetworking Protocol). Furthermore, the exposure of users to the prolific Internet services means that similar service models will have to be provided by the next generation telecom networks. The clash between these two opposite approaches poses important challenges for network operators. This is due to the fundamental risk associated with their networks turning into mere bit pipes. In order for future telecom networks to be economically viable, they should provide similar user experience with Internet services, albeit in a more managed and reliable manner.

The increasingly dynamic nature of the telecommunications scene is expected to go beyond the technical domain and also cover business models and socioeconomic aspects of telecommunications, eventually giving rise to the user-centric network vision highlighted above.

There are many challenges, both technical and socioeconomic, that needs to be addressed for this vision to come true, such as the need for a standardized view of QoE among all stakeholders that should act as a common performance and valuation criterion.







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