| 1. |
- Carlsson, Patrik, et al.
(författare)
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Obtaining Reliable Bit Rate Measurements in SNMP-Managed Networks
- 2002
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Konferensbidrag (refereegranskat)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.
(författare)
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Measurements of Application-Perceived Throughput in DAB, GPRS, UMTS and WLAN Environments
- 2005
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Konferensbidrag (refereegranskat)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.
(författare)
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Network Selection Box : An Implementation of Seamless Communication
- 2006
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Konferensbidrag (refereegranskat)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. |
- Chevul, Stefan
(författare)
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On Application-Perceived Quality of Service in Wireless Networks
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wireless and Mobile Internet have changed the way people and businesses operate. Communication from any Internet access point, including wireless networks such as UMTS, GPRS or WLAN has enabled organizations to have a mobile workforce. However, networked applications such as web, email, streaming multimedia etc. rely upon the ability of timely data delivery. The achievable throughput is a quality measure for the very task of a communication system, which is to transport data in time. Throughput is thus one of the most essential enablers for networked applications. While in general, throughput is defined on network or transport level, the application-perceived throughput reflects the Quality of Service from the viewpoints of the application and user. The focus of the thesis is on the influence of the network on the applicationperceived Quality of Service and thus the user perceived experience. An analysis of application based active measurements mimicking the needs of streaming applications is presented. The results reveal clear influence of the network on the application-perceived Quality of Service seen from variations of application-perceived throughput on small time scales. Results also indicate that applications have to cope with considerably large jitter when trying to use the nominal throughputs. It was observed that the GPRS network had considerable problems in delivering packets in the downstream direction even when the nominal capacity of the link was not reached. Finally, the thesis discusses the suitability of wireless networks for different mobile services, since the influence of the network on the application-perceived Quality of Service is of great significance when it comes to customer satisfaction. Therefore, application-perceived Quality of Service in wireless networks must also be considered by the mobile application programmer during the application development.
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| 6. |
- Eriksén, Sara, et al.
(författare)
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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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Konferensbidrag (refereegranskat)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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| 7. |
- Fiedler, Markus, et al.
(författare)
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Communication requirements of generic services for Intelligent Transport Systems
- 2004
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to meet their users’ expectations and to be of efficient help for people using or maintaining Intelligent Transport Systems (ITS), related services need efficient support from the underlying communication systems, which in turn requires profound knowledge of those needs. This paper presents an approach to gather services into generic groups and 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 the matching towards technical parameters as e.g. throughput offered by a communication network can be performed. Upon comparing needs with offers, the feasibility of a certain communication technology for a certain type of service can be determined, which in turn helps to choose the right kind of connectivity in order to yield the desired degree of availability, performance, security and cost. This work is carried out within the VINNOVA-sponsored project PIITSA (Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions) conducted by Aerotech Telub, Blekinge Tekniska Högskola, Statens Provningsanstalt Borås and Vägverket, respectively.
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| 8. |
- Fiedler, Markus, et al.
(författare)
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Generic communication requirements of its-related mobile services as basis for seamless communications.
- 2005
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Konferensbidrag (refereegranskat)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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| 9. |
- Fiedler, Markus, et al.
(författare)
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Measurements and analysis of application-perceived throughput via mobile links
- 2005
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Konferensbidrag (refereegranskat)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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| 10. |
- Fiedler, Markus, et al.
(författare)
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Measurements and analysis of application-perceived throughput via mobile links
- 2011
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Ingår i: Lecture Notes in Computer Science. - : Springer. - 0302-9743 .- 1611-3349. ; 5233, s. 37-69
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Tidskriftsartikel (refereegranskat)abstract
- Application-perceived throughput plays a major role for the performance of networked applications and user experience and thus, for network selection decisions. To support the latter, this tutorial paper investigates the process of user-perceived throughput in GPRS and UMTS systems seen over rather small averaging intervals, based on test traffic mimicking the needs of streaming applications, and analyzes the results with aid of summary statistics. 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 and indicate that applications have to cope with significant jitter when trying to exploit the nominal throughputs. In GPRS, the promised average throughputs are not reached in downlink direction; instead, significant packet loss occurs. Furthermore, with aid of causality arguments for an equivalent bottleneck, bounds for the extra delay of the first packet sent via mobile links is derived from throughput measurements.
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