The principles of distributed object oriented programming offer great possibilities for flexible ... more The principles of distributed object oriented programming offer great possibilities for flexible architectures in multiple fields. In telecommunications, an architecture called Telecommunication Information Networking Architecture has been developed using these very principles. It allows telecommunication services to be implemented using software objects that in turn can be executed in a location transparent way in a network. The location transparency offers
Traffic measurements in broadband access networks are crucial from several points of view. A bett... more Traffic measurements in broadband access networks are crucial from several points of view. A better understanding of traffic patterns can lead to more efficient network design, which leads to energy and cost savings for the operator and improved end user services. This paper reports on selected traffic measurement results from the Celtic TRAMMS project. The measurements were performed in broadband
International Journal of Vehicular Technology, 2011
... is the decision mechanism employed for message delivery and repetition, that is, finding an i... more ... is the decision mechanism employed for message delivery and repetition, that is, finding an intelligent way ... waiting time starts its own periodic broadcast sequence once the waiting phase is over. ... especially for transmission ranges higher than 200 m. The ratio of cars they reach ...
Sustainable Computing: Informatics and Systems, 2012
ABSTRACT In this paper, we propose a general power model along with a versatile optimization meth... more ABSTRACT In this paper, we propose a general power model along with a versatile optimization methodology that can be applied to different applications for minimizing service delay while satisfying power budget in data centers. We test our methodology on two totally different applications from both cloud computing and enterprise scenarios. Our solution is novel in that it takes into account the dependence of power consumption on temperature, attributed to temperature-induced changes in leakage current and fan speed. While this dependence is well-known, we are the first to consider it in the context of minimizing service delay. Accordingly, we implement our optimization strategies with Hadoop, Tomcat, and MySQL on a 40-node cluster. The experimental results show that our solution cannot only limit the power consumption to the power budget but also achieves smaller delay against static solutions and temperature oblivious DVFS solutions.
2014 22nd International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2014
ABSTRACT Recent changes in user employment of Internet based services, new deployment technologie... more ABSTRACT Recent changes in user employment of Internet based services, new deployment technologies for mobile networks as well as an ongoing realisation of fixed and mobile converged networks e.g. the EU FP7 project COMBO, are significant examples of enablers for increasing demands on DSL links, especially VDLS2. Investigating cross-layer dependencies between all layers in the OSI reference model becomes increasingly important. In this paper we present an analytical model and experimental results for the relation between impulse noise on a VDSL2 link and the effect this have on the network layer packet loss. We show how the packet loss rate is dependent not only on the disturbance signal level and periodicity but also on the link utilisation.
ABSTRACT Resource-optimization of the infrastructure for service oriented applications require ac... more ABSTRACT Resource-optimization of the infrastructure for service oriented applications require accurate performance models. In this paper we investigate the performance dynamics of a MySQL/InnoDB database server with write-heavy workload. The main objective of our investigation was to understand the system dynamics due to the buffering of disk operations that occurs in database servers with write-heavy workload. In the paper, we characterize the traffic and its periodic anomalies caused by flushing of the buffer. Further, we present a performance model for the response time of the requests and show how this model can be configured to fit with actual database measurements.
Internet usage is evolving, from the traditional WWW usage (i.e. downloading web pages), to tripl... more Internet usage is evolving, from the traditional WWW usage (i.e. downloading web pages), to triple-play usage where households may have all their communication services (telephony, data, TV) through their broadband access connection. The challenge is to design IP access networks so that they can deliver services with strict QoS demands such as IPTV at the same time as having capacity for (from the operator's perspective) unwanted traffic, for example file sharing, demanded by the users. One important part in meeting this research challenge is to identify and monitor Internet usage. Traffic modeling is tightly coupled both to traffic measurements and to engineering and techno economics. The focus of the measurements in this paper lies on analyzing parameters of interest for network management decisions, i.e. traffic volume, application usage, locality of content and popularity of content. For locality analysis, the geographical end points of data flows are studied. For content po...
Performance modeling is an important topic in capacity planning and overload control for web serv... more Performance modeling is an important topic in capacity planning and overload control for web servers. We present a queueing model of an Apache web server that uses bursty arrival traffic. The arrivals of HTTP requests is assumed to be a Markov Modulated Poisson Process and the service discipline of the server is processor sharing. The total number of requests that can be processed at one time is limited to K. We obtain web server performance metrics such as average response time, throughput and blocking probability by simulations. Compared to other models, our model is conceptually simple. The model has been validated through measurements and simulations in our lab. The per- formance metrics predicted by the model fit well to the experimental outcome. Keywords--Internet, World Wide Web, web server, perfor- mance model, MMPP.
Many commercial web sites, as web stores, have recently experienced perform- ance problems due to... more Many commercial web sites, as web stores, have recently experienced perform- ance problems due to the growth of Internet trading. One way to improve a site's performance during overload is to introduce admission control mechanisms. In this paper we develop and investigate two admission control schemes specifi- cally for distributed commercial web sites. One of the schemes is request-based and
... Wireless networks usually show high rate of packet losses and these losses may trigger the co... more ... Wireless networks usually show high rate of packet losses and these losses may trigger the congestion control in TCP even though there is no congestion. ... Ludwig and Rathonyi [13] devel-oped a link layer enhancement for GSM. Chandran et al. ...
The principles of distributed object oriented programming offer great possibilities for flexible ... more The principles of distributed object oriented programming offer great possibilities for flexible architectures in multiple fields. In telecommunications, an architecture called Telecommunication Information Networking Architecture has been developed using these very principles. It allows telecommunication services to be implemented using software objects that in turn can be executed in a location transparent way in a network. The location transparency offers
Traffic measurements in broadband access networks are crucial from several points of view. A bett... more Traffic measurements in broadband access networks are crucial from several points of view. A better understanding of traffic patterns can lead to more efficient network design, which leads to energy and cost savings for the operator and improved end user services. This paper reports on selected traffic measurement results from the Celtic TRAMMS project. The measurements were performed in broadband
International Journal of Vehicular Technology, 2011
... is the decision mechanism employed for message delivery and repetition, that is, finding an i... more ... is the decision mechanism employed for message delivery and repetition, that is, finding an intelligent way ... waiting time starts its own periodic broadcast sequence once the waiting phase is over. ... especially for transmission ranges higher than 200 m. The ratio of cars they reach ...
Sustainable Computing: Informatics and Systems, 2012
ABSTRACT In this paper, we propose a general power model along with a versatile optimization meth... more ABSTRACT In this paper, we propose a general power model along with a versatile optimization methodology that can be applied to different applications for minimizing service delay while satisfying power budget in data centers. We test our methodology on two totally different applications from both cloud computing and enterprise scenarios. Our solution is novel in that it takes into account the dependence of power consumption on temperature, attributed to temperature-induced changes in leakage current and fan speed. While this dependence is well-known, we are the first to consider it in the context of minimizing service delay. Accordingly, we implement our optimization strategies with Hadoop, Tomcat, and MySQL on a 40-node cluster. The experimental results show that our solution cannot only limit the power consumption to the power budget but also achieves smaller delay against static solutions and temperature oblivious DVFS solutions.
2014 22nd International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2014
ABSTRACT Recent changes in user employment of Internet based services, new deployment technologie... more ABSTRACT Recent changes in user employment of Internet based services, new deployment technologies for mobile networks as well as an ongoing realisation of fixed and mobile converged networks e.g. the EU FP7 project COMBO, are significant examples of enablers for increasing demands on DSL links, especially VDLS2. Investigating cross-layer dependencies between all layers in the OSI reference model becomes increasingly important. In this paper we present an analytical model and experimental results for the relation between impulse noise on a VDSL2 link and the effect this have on the network layer packet loss. We show how the packet loss rate is dependent not only on the disturbance signal level and periodicity but also on the link utilisation.
ABSTRACT Resource-optimization of the infrastructure for service oriented applications require ac... more ABSTRACT Resource-optimization of the infrastructure for service oriented applications require accurate performance models. In this paper we investigate the performance dynamics of a MySQL/InnoDB database server with write-heavy workload. The main objective of our investigation was to understand the system dynamics due to the buffering of disk operations that occurs in database servers with write-heavy workload. In the paper, we characterize the traffic and its periodic anomalies caused by flushing of the buffer. Further, we present a performance model for the response time of the requests and show how this model can be configured to fit with actual database measurements.
Internet usage is evolving, from the traditional WWW usage (i.e. downloading web pages), to tripl... more Internet usage is evolving, from the traditional WWW usage (i.e. downloading web pages), to triple-play usage where households may have all their communication services (telephony, data, TV) through their broadband access connection. The challenge is to design IP access networks so that they can deliver services with strict QoS demands such as IPTV at the same time as having capacity for (from the operator's perspective) unwanted traffic, for example file sharing, demanded by the users. One important part in meeting this research challenge is to identify and monitor Internet usage. Traffic modeling is tightly coupled both to traffic measurements and to engineering and techno economics. The focus of the measurements in this paper lies on analyzing parameters of interest for network management decisions, i.e. traffic volume, application usage, locality of content and popularity of content. For locality analysis, the geographical end points of data flows are studied. For content po...
Performance modeling is an important topic in capacity planning and overload control for web serv... more Performance modeling is an important topic in capacity planning and overload control for web servers. We present a queueing model of an Apache web server that uses bursty arrival traffic. The arrivals of HTTP requests is assumed to be a Markov Modulated Poisson Process and the service discipline of the server is processor sharing. The total number of requests that can be processed at one time is limited to K. We obtain web server performance metrics such as average response time, throughput and blocking probability by simulations. Compared to other models, our model is conceptually simple. The model has been validated through measurements and simulations in our lab. The per- formance metrics predicted by the model fit well to the experimental outcome. Keywords--Internet, World Wide Web, web server, perfor- mance model, MMPP.
Many commercial web sites, as web stores, have recently experienced perform- ance problems due to... more Many commercial web sites, as web stores, have recently experienced perform- ance problems due to the growth of Internet trading. One way to improve a site's performance during overload is to introduce admission control mechanisms. In this paper we develop and investigate two admission control schemes specifi- cally for distributed commercial web sites. One of the schemes is request-based and
... Wireless networks usually show high rate of packet losses and these losses may trigger the co... more ... Wireless networks usually show high rate of packet losses and these losses may trigger the congestion control in TCP even though there is no congestion. ... Ludwig and Rathonyi [13] devel-oped a link layer enhancement for GSM. Chandran et al. ...
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Papers by Maria Kihl