Introduction to Quality of Service

Introduction to Quality of Service

Eva Ibarrola (University of the Basque Country, Spain), Fidel Liberal (University of the Basque Country, Spain) and Armando Ferro (University of the Basque Country, Spain)
DOI: 10.4018/978-1-61520-791-6.ch001
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The advent and rise of broadband technologies and new applications and services have led to a complex heterogeneous scenario in which providing Quality of Service (QoS) has become a compelling issue. Furthermore, the competitive condition of the telecommunications environment has caused user’s perception of quality to become one of the most differential factors for service providers. Due to this fact, QoS must not only attend to specific technical metrics, but more important, QoS criteria should be defined to assure the level of quality to fulfil the users’ requirements. In this new context, the definition of effective user-oriented QoS management models and frameworks has become a matter of contention. This chapter aims to provide readers a comprehensive analysis of the entire significance of a user-centered approach for quality of service management. For this purpose, a review of the most important issues related to the subject is provided.
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Quality of service (QoS) can be defined in many different ways. If we break the term down into its component parts, the word “service” can be understood as the provision of value in some domain. Therefore, the connotation of the term “service” will be tightly linked to the considered area: business, engineering, manufacturing, computer science. The meaning of “quality” has changed over time. Quality has been defined as the degree of excellence of a product (Abbott, 1955), bundle of characteristics desired by consumers (Lancaster, 1966), the degree to which a service conforms with specific requirements (Crosby, 1979; Juran, 1999) or the degree of user’s satisfaction with the service (Ishikawa, 1985; Kano, 1984; Parasuraman, Zeithaml, & Berry, 1996). The most progressive views of quality include most of the issues that have been referred in the above definitions: products, services, characteristics, user’s requirements and user’s satisfaction. One example is how the International Standard Organization (ISO) defines quality in ISO 8402 (1986, p.3.1): “The totality of features and characteristics of an entity (product or service) that bear on its ability to satisfy stated or implied needs”. Considering this extension, several quality general frameworks and models like ISO 9000 (ISO, 2005), TQM/EFQM (Dale & Cooper, 1994) and Six-Sigma (Harry & Schroeder, 2000) have been widely adopted and deployed in business and other general environments but, still, none of them has been found to be fully satisfactory for telecommunication environment.

Despite the fact the term “Quality of Service” has been traditionally linked to one specific domain (communications), QoS definition has also evolved over the time. ITU-T Recommendation E.800 (ITU-T, 1994, p.3) defines quality of service as “the collective effect of service performance which determines the degree of satisfaction of a user of the service”. Some authors (TMF, 2005b) find this definition excessively narrow and ITU-T seem to agree with a later revision of this Recommendation (ITU-T, 2008, p.4) which changes the QoS definition to one derived from the ISO 8402: “Totality of characteristics of a telecommunications service that bear on its ability to satisfy stated and implied needs of the user of the service”. The amended Recommendation adds importance to the user’s perception by remarking:

Of particular interest is QoS experienced by the user (expressed by QoSE or QoSP - QoS perceived). QoSE is influenced by the delivered QoS and the psychological factors influencing the perception of the user. Understanding of the QoSE is of primary importance to help to optimize revenue and resources of the service provider. (ITU-T, 2008, p.3)

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