To accommodate applications with highly variable degrees and categories of Quality of Service (QoS) requirements, a major effort has been invested to overcome the traditional best-effort service quality of the Internet [1],[2]. Nevertheless, there has been a shift towards weak QoSassurance paradigms based on the differentiation of different QoS levels [3]. What is currently missing is a technique for specifying user preferences for QoS and network charging mechanisms. If the Internet is to remain economically viable, demand for Internet services must be maintained. Specifying users' QoS requirements therefore has potentially crucial implications for providing a degree of service that will encourage users to pay for the quality that they receive. This paper investigates the role of conceptual design in establishing users' mental representations of Internet services and their charges. We report empirical work that shows how these models can be used to predict the acceptability of Internet services. Preliminary guidelines for the design of QoS charging mechanisms are presented.

Due to the increasing popularity of applications such as media streaming and videoconferencing, multimedia traffic dominates the Internet today. So far, research into Quality of Service (QoS) for networked multimedia has focused on technical performance at the network level, rather than the quality experienced by the end-user. With a more service-oriented culture, however, the notion of user-centered QoS is gaining hold; this raises the question of how to measure quality experienced by end-users in meaningful terms. This paper introduces a 3-dimensional approach to assessing audio and video quality in networked multimedia applications: measuring task performance, user satisfaction and user cost (in terms of physiological impact). We argue that - for any given application - the relative importance of each dimension needs to be determined, and assessment techniques selected accordingly.

To create acceptable levels of Quality of Service (QoS), designers need to be able to predict users' behaviour in response to different levels of QoS. However, predicting behaviour requires an understanding of users' requirements for specific tasks and contexts. This paper reports qualitative and experimental research that demonstrates that future network service must be based on an old principle: service and its associate cost must represent value in terms of the contribution it makes to customers' goals. Human Computer Interaction (HCI) methods can be applied to identify users' goals and associated QoS requirements. Firstly, we used a qualitative approach to establish the mental concepts that users apply when assessing network services and charges. The subsequent experimental study shows that users' require certain types of feedback at the user interface to predict future levels of quality. Price alone cannot be used to regulate demand for QoS.

The number of network users is expected to triple between 1998 and 2002 (Cullinane, 1998). While a vision of the future Internet offers the potential to break traditional barriers in communications and commerce, the current level of service does not satisfy the requirements of many users (Network Reliability Steering Committee, 1998, Cullinane, 1998). This thesis is concerned with users' perceptions of Quality of Service (QoS), and their attitudes to charging mechanisms applied to wide-area networks. Whilst the majority of research in this area has been conducted from a technical point of view, studies addressing issues of QoS and charging from a users' perspective are limited. The aim of this research was to investigate the latter issue to provide a more complete and integrated perspective on QoS and charging in the user-network system. The thesis first addresses previous work that looks at QoS and charging, establishing a justification for the new research. This part of the thesis concludes that, whilst part of our understanding of QoS requirements can be explained by technical and economic paradigms, additional research is required to examine the perceptions and concomitant behaviour of users. The methodology employed is outlined in relation to obtaining this objective. The second part of the thesis details work undertaken. This work has made the following main contributions: *Developed a set of conceptual models that describe users' perceptions of network QoS. *Shown that these models can be used to predict users' behaviour in different contexts by capturing subjective evaluations of QoS. * Shown how a combination of established and new methods can be successfully applied in capturing and assessing users' perceptions of QoS. *Shown how the new data relates to technical and econometric research. *Provided concrete examples of how the new research can inform network systems design. The work documented in this thesis has implications for user-centred, technical and econometric research. This thesis therefore contributes, not only to the field of HCI to which it is most closely related, but provides guidelines that can be used by econometricians and network designers. The research from all three of these perspectives is concerned with the efficient function of network resource allocation systems. The work documented in this thesis has suggested how it is possible to integrate these perspectives to provide valued levels of QoS to users.

The field of molecular biology is in a remarkably rapid period of change, as the genome sequencing projects and new experimental technologies have generated an explosion of data. To analyze and draw insights from the vast amounts of information, biologists use a new generation of bioinformatics software tools, often working closely with mathematicians and computer scientists. There are elements of both collision and convergence in these interdisciplinary encounters. We conducted user studies with biologists engaged in investigating the molecular basis of disease. We describe several issues that arise in this collision/convergence of disciplines, drawing on the notion of boundary objects in-the-making. We provide recommendations on building technology for people whose work now sits at the crossroads of diverse and rapidly changing scientific fields.

The number of Internet users is expected to triple between 1998 and 2002 largely because of new applications (such as videoconferencing) and new services (such as e-commerce). This shift in usage imposes higher Quality of Service (QoS) requirements at different levels of granularity. It also means that the traditional Internet way of managing quality (best-effort) has to be replaced by a more service-oriented approach. The aim of this paper is to investigate end-users' cognitive and perceptive QoS requirements. We present empirical results on user QoS preferences and QoS graduations. Guidelines for translating these results into metrics that can be used to guide resource allocation mechanisms are discussed.

As the number of Web users and the diversity of Web applications continues to explode, Web Quality of Service (QoS) is an increasingly critical issue in the domain of e-commerce. This paper presents experiments designed to estimate users' tolerance of QoS in the context of e-commerce. In addition to objective measures, we discuss contextual factors that influence these thresholds and show how users' conceptual models of Web tasks affect their expectations. We then show how user thresholds of tolerance can be taken into account when designing Web servers. This integration of user requirements for QoS into systems design is ultimately of benefit to all stakeholders in the design of Internet services.

Multimedia communication has gained increasing attention, both from the application side and the network provider side. While resource provisioning for QoS support in packet switched networks has led to the design and development of sophisticated QoS architectures, notably ATM, IntServ or DiffServ, research has not exactly been user or application-context centered. In the cause of the evolution of QoS architectures, the integrated service network approach has lost momentum, and with it, the notion of QoS guarantees. Differentiation of QoS classes within the DiffServ framework is based on the definition of various per-hop behaviors. What is currently missing is a technique for specification and mapping of application and user QoS preferences onto evolving service profiles. In addition, adaptation of applications (and users) is becoming increasingly important in the face of dominating weak QoS-assurance paradigms, both in wireline and wireless environments. As a prerequisite, this paper investigates cognitive and perceptive conditioning of users and applications in a situated setting. The contribution of this paper is twofold: first, essential empirical results on user QoS preferences and QoS graduations are presented, and second, methodological foundations are laid for investigating user-centered QoS

Growing usage and diversity of applications on the Internet makes Quality of Service (QoS) increasingly critical [15]. To date, the majority of research on QoS is systems oriented, focusing on traffic analysis, scheduling, and routing. Relatively minor attention has been paid to user-level QoS issues. It is not yet known how objective system quality relates to users' subjective perceptions of quality. This paper presents the results of quantitative experiments that establish a mapping between objective and perceived QoS in the context of Internet commerce. We also conducted focus groups to determine how contextual factors influence users' perceptions of QoS. We show that, while users' perceptions of World Wide Web QoS are influenced by a number of contextual factors, it is possible to correlate objective measures of QoS with subjective judgements made by users, and therefore influence system design. We argue that only by integrating users' requirements for QoS into system design can the utility of the future Internet be maximized.

The number of heterogeneous networked applications is constantly increasing. It is likely that network resources will have to be partitioned according to the different Quality of Service (QoS) demands made by the users of these applications. One way of implementing a partitioned network – favored in technical literature − is in terms of quality-based pricing (e.g.[1],[2],[3]). Most published proposals for partitioned networks assume users’ assessments of the quality they receive mirrors the objective quality delivered at the network level (measurable through characteristics such as packet loss and delay). It is also assumed that users are prepared to pay more for higher levels of objective QoS when they need it. In this paper, we demonstrate that these assumptions may not be correct. We report an experiment in which users’ QoS requirements for interactive audio were investigated. During the experiment the QoS received was linked to an expendable resource. We also established participant’s attitudes to dynamic pricing during semi-structured interviews. Our results suggest that users’ assessments of the value of QoS received is influenced by a number of different factors – hence, the same level of quality will receive different assessments in different circumstances. We also found that a Predictable level of QoS is a key requirement for users of networked applications. The results from the interviews suggest that, when users accept a pricing scheme they develop strategies to optimize their use of an expendable resource. We conclude by outlining the implications of our findings for the design of resource allocation and pricing schemes for the future Internet.

this paper set out to exam ine w hether the characteristics used to define QoS at thenetw ork level m atch the quality requirem ents of those w ho use netw ork applications. Af ter all, users are

Shared networks are now able to support a wide range of applications, including real-time multimedia. This has led the networking community to consider a wider range of network Quality of Service (QoS) guarantees and pricing schemes. To date, the QoS required by networked multimedia applications has been described in terms of technical parameters. We argue that, in order to maximize the realized quality of any network, the QoS requirements of networked multimedia applications should be based on the value that users ascribe to the media quality they receive in the content of a particular task. This argument is supported with results from a set of studies in which users' perceptions of media quality was investigated for a listening task. We found that users' expectancies of quality directly influenced their ratings: low expectancies produce higher ratings for the same level of objective quality-- provided that quality is predictable. In conclusion, we outline the implications of our studies for the design of networked multimedia applications and the network services that support them.

Shared networks, such as the Internet, are fast becoming able to support heterogeneous applications and a diverse user community. In this climate, it becomes increasingly likely that some form of pricing mechanism will be necessary in order to manage the quality of service (QoS) requirements of different applications. So far, research in this area has focused on technical mechanisms for implementing QoS and charging. This paper reports a series of studies in which users' perceptions of QoS, and their attitudes to a range of pricing mechanisms, were investigated. We found that users' knowledge and experience of networks, and the real-world task they perform with applications, determine their evaluation of QoS and attitude to payment. Users' payment behavior is governed by their level of confidence in the performance of salient QoS parameters. User confidence, in turn, depends on a number of other factors. In conclusion, we argue that charging models that undermine user confidence are not only undesirable from the users' point of view, but may also lead to user behavior that may have a negative impact on QoS.