| 1. |
- Carlsson, Patrik, et al.
(author)
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Obtaining Reliable Bit Rate Measurements in SNMP-Managed Networks
- 2002
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Conference paper (peer-reviewed)abstract
- The Simple Network Management Protocol, SNMP, is the most widespread standard for Internet management. As SNMP stacks are available on most equipment, this protocol has to be considered when it comes to performance management, traffic engineering and network control. However, especially when using the predominant version 1, SNMPv1, special care has to be taken to avoid erroneous results when calculating bit rates. In this work, we evalute six off-the-shelf network components. We demonstrate that bit rate measurements can be completely misleading if the sample intervals that are used are either too large or too small. We present solutions and work-arounds for these problems. The devices are evaluated with regards to their updating and response behavior.
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| 2. |
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| 3. |
- Chevul, Stefan, et al.
(author)
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Measurements of Application-Perceived Throughput in DAB, GPRS, UMTS and WLAN Environments
- 2005
-
Conference paper (peer-reviewed)abstract
- Communication services are expected to deliver the desired information in a timely manner without challenging the user’s patience. The corresponding offers by networks are reflected in user- or applications-perceived throughput, which is measured end-to-end for different mobile and wireless networks, namely Digital Audio Broadcast (DAB), General Packet Radio Service (GPRS), Universal Mobile Telecommunication Systems (UMTS), and Wireless Local Area Networks (WLAN). The measurements are based on passive monitoring of throughput statistics for active test traffic and reveal amongst others different kinds of changes of traffic burstiness induced by mobile up- and downlinks and by buffering, respectively. The results will be used for seamless communication, i.e. automatic network selection within the project PIITSA (Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions) aiming at maintaining user-perceived performance and security at the desired levels while keeping communication cost as small as possible.
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| 4. |
- Chevul, Stefan, et al.
(author)
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Network Selection Box : An Implementation of Seamless Communication
- 2006
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Conference paper (peer-reviewed)abstract
- In recent years it has become evident that mobility support will have profound impact on current and future wireless networks. Users expect service connectivity at any place at anytime without having to think about the underlying communication systems used in that particular moment in time. On this background, this paper presents a ready to deploy implementation of a mobility framework that supports seamless communication and represents an important enabler for adaptive applications through its simple QoS feedback mechanism. The framework selects the best available network through a decision algorithm that takes advantage of a link performance monitoring concept. The performance evaluation of the proposed framework is also presented in this paper.
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| 5. |
- Eriksén, Sara, et al.
(author)
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Mapping service quality : measuring and comparing quality of experience and quality of service for Internet-based map services
- 2007
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Conference paper (peer-reviewed)abstract
- In this paper, we present an on-going research project in which we are focusing on examining how users of map-based services on-line experience the quality of these services when the traffic load is high, and how the users' experiences of acceptable or not acceptable quality can be related to measurable parameters which can be used to manage network traffic and improve technical solutions. The project is a multi- and interdisciplinary project in cooperation between researchers within human work science and informatics, and researchers within telecommunication systems. Additionally, there are two external partners in the project: a provider of Internet-based map services, and a municipality which uses this provider's map services regularly. One of the main methodological issues addressed in the project is how laboratory based, quantitative research methods from research on Quality of Service in the telecommunication systems area can be related to qualitative research methods focusing on workplace- or other live-world based use situations and Quality of Expereince as defined by users of the services. How can experiments and studies be designed, and results shared, such that both network traffic measuring and evaluation of user experiences retain their own paradigmatic validity and relevance, while fruitfully informing service design?
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| 6. |
- Fiedler, Markus, et al.
(author)
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Generic communication requirements of its-related mobile services as basis for seamless communications.
- 2005
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Conference paper (peer-reviewed)abstract
- In order to meet user expectations and to be of efficient help for people using or implementing Intelligent Transport Systems and Services (ITS), mobile ITS-related services need efficient support from the underlying communication systems, which in turn requires profound knowledge of those needs. As a first step towards an optimal automatic choice of communication technologies in order to provide for seamless communications, this paper groups services into generic groups and presents a framework to classify their needs in terms of availability, performance, security and cost in a generic manner. These needs are consequently seen from the user’s perspective, but formulated in a way such that they can be matched towards known network parameters. Upon comparing needs with offers, the feasibility of a certain communication technology for a certain type of service can be determined both proactively and reactively, which helps to automatically select the right kind of connectivity in order to yield the desired degree of availability, performance, security and cost. We motivate for instance the need for determining and monitoring applicationperceived speeds, a multi-level security models and the one-stop service concept. We also provide an example on how these needs can be matched to offers by different networks.
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| 7. |
- Fiedler, Markus, et al.
(author)
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Measurements and analysis of application-perceived throughput via mobile links
- 2005
-
Conference paper (peer-reviewed)abstract
- Application-perceived throughput plays a major role for the performance of networked applications and thus for user experience. Especially in mobile environments, throughput is limited, which is a challenge for applications and users. On this background, this tutorial paper investigates the process of user-perceived throughput in GPRS and UMTS systems seen over rather small averaging intervals. It discusses the corresponding active measurements mimicking the needs of streaming applications and analyzes results with aid of summary statistics, histograms and autocorrelation coefficients. These results reveal a clear influence of the network, seen from variations and autocorrelation of application-perceived throughput mostly on the one-second time scale. Such an influence has to be considered when choosing the right kind of network for a specific task. To that aim, the investigated metrics will serve as input to a multi-criteria decision process to determine the proper network for a specific service. The results indicate that, applications have to cope with considerably large jitter when trying to use the nominal throughputs. In GPRS, the promised average throughputs are not even reached in downlink direction; instead, a quite large amount of packet loss occurs. With aid of causality arguments for an equivalent bottleneck, bounds for the extra delay of the first packet sent via mobile links can in fact be derived from throughput measurements.
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| 8. |
- Fiedler, Markus, et al.
(author)
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Quality of Experience and Quality of Service in a Service Supply Chain
- 2007
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Conference paper (other academic/artistic)abstract
- Extended Abstract: Quality of Service and Quality of Experience Networked ICT services keep on invading our private and professional lives. Increasingly many work processes depend on ICT services, which obviously define the efficiency of how tasks are solved. The perceived usability of a service is thereby heavily linked to the performance of the service, for instance its responsiveness. Users do not like to wait unnecessarily; long response times might interrupt their flow of thoughts and finally entail a loss of interest. Quality aspects seen from the user’s point of view have gained importance. Users rate the quality of the ICT services explicitly (by rating and commenting them) or implicitly (by using them happily, reluctantly or not at all). In case several alternative ICT services exist and pricing is not a primary matter of concern, quality may become the discriminating factor between different providers and might decide upon success or failure. While the rather traditional notion Quality of Service (QoS) is mostly related to technical quality parameters, the recently established notion of Quality of Experience (QoE) extends the notion of quality to include user perception. Obviously, QoE has strong subjective components and is also connected to the situation and context in which the user finds him- or herself. For instance, a certain response time of a service (e.g. providing an answer within four seconds) can be considered sufficient in a relaxed situation, but not when the user is in a stressed situation, e.g. having to make an urgent decision based on the result displayed by the service. User stress takes an impact on the threshold(s) marking off different levels of perception (excellent; good; fair; bad; etc.). More background to this particular issue is found in [2]. In the course of this work, we aim at finding quantitative relationships between the context in which the user finds him- or herself and the expectations regarding the – technical – performance in terms of QoS parameters such as the response time. Service Supply Chains Another important trend is the composition of tailored services, adapted to the needs of specific users in specific situations, out of basic service elements, potentially offered by different providers. Such a composite service forms a Service Supply Chain (SSC) consisting of one or several service elements. When the user activates the main service, the latter activates service elements as needed, handles the corresponding inputs, waits for deliveries, processes the corresponding outputs and finally returns the result to the user. The latter is sitting at the end of the SSC and has to wait for all service elements to finish before the result can be consumed. I.e., the user perceives the maximum of all response times in the system. In order to control user perception through service management, it is important to determine the weak links of SSC that provide the largest contributions to the response times in order to be able to cope with them in order to improve the user’s QoE perception. A particular case: Map-SSC In this work, we look at a particular service, a map service. These activities are part of a Swedish national project, funded by the Internet Infrastructure Foundation (.se) from funds earned by licensing Swedish Internet domains. We will observe professional users (planners at the municipality) in different stress situations when performing two map-related tasks, downloading a map and clicking a symbol in the displayed map in order to get more detailed information. The latter task relates to a SSC, consisting of a fetch-and-display service and an information service. Furthermore, we will introduce stress on network level by shaping the traffic. This will allow us to correlate user perception with thresholds of QoS parameters and thus to see the impact of user and/or network stress on Service Level Agreements (SLA). The map service provider participating in the project will instrument the SSC such that we will be able to monitor the response time at different places on application level in order to identify the critical links in the SSC. Furthermore, corresponding measurements on network level will be carried out in order to visualize the impact of the network stacks in client and servers, respectively.
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| 9. |
- Fiedler, Markus, et al.
(author)
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The Network Utility Function : A practicable concept for assessing network impact on distributed services
- 2005
-
Conference paper (peer-reviewed)abstract
- Based on the need for distributed end-to-end quality management for next generation Internet services, this paper presents a ready-to-deploy quality assessment concept for the impact of the network on the service performance. The proposed Network Utility Function (NUF) combines the observed network utility at the inlet and the outlet. Thus, it captures the damping effect of the network onto user-perceived quality from an end-to-end perspective. As opposed to incomprehensible QoS parameters such as delay and loss, the NUF is highly intuitive due to its mapping to a simple value between 0 and 1. We demonstrate the capabilities of the proposed concept for a special NUF, the Throughput Utility Function (TUF) by realistic simulation.
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| 10. |
- Fiedler, Markus, et al.
(author)
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The Throughput Utility Function : Assessing network impact on mobile services
- 2005
-
Conference paper (peer-reviewed)abstract
- Based on the need for distributed end-to-end quality management for next-generation mobile Internet services, this paper presents a ready-to-deploy quality assessment concept for the impact of the network on the performance of mobile services. We consider the throughput utility function (TUF) as a special case of the network utility function (NUF). These functions combine the observed network utility at the inlet and the outlet of a mobile network. NUF and TUF capture the damping effect of the network onto user-perceived quality from an end-to-end perspective. As opposed to sometimes hard-to-evaluate QoS parameters such as delay and loss, the NUF is highly intuitive due to its mapping to a simple value between 0 and 100 %, which reflects user perception. We demonstrate the capabilities of the proposed TUF by measurements of application-perceived throughput conducted in a mobile, i.e. GPRS and UMTS network.
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