Maria Kihl

... 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 ...

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.

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.

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.

... 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. ...

ABSTRACT In this work, we study YouTube traffic characteristics in a medium-sized Swedish residential municipal network that has - 2600 mainly FTTH broadband-connected households. YouTube traffic analyses were carried out in the perspective of video clip category and duration, in order to understand their impact on the potential local network caching gains. To the best of our knowledge, this is the first time systematic analysis of YouTube traffic content in the perspective of video clip category and duration in a residential broadband network. Our results show that the requested YouTube video clips from the end users in the studied network were imbalanced in regarding the video categories and durations. The dominating video category was Music, both in terms of the total traffic share as well as the contribution to the overall potential local network caching gain. In addition, most of the requested video clips were between 2-5 min in duration, despite video clips with durations over 15 min were also popular among certain video categories, e.g. film videos.

ABSTRACT Long Term Evolution (LTE) is the new generation of infrastructure-based wireless technologies that can be used for vehicular communications, and already a standard considered as the preliminary version of 4G mobile communications. It provides a cellular networks-based solution, generally called vehicle to infrastructure (V2I), for vehicular safety applications. In this work, we evaluate the performance of different downlink scheduling strategies under various urban and rural scenarios, in which voice, video and safety data traffic coexist. The traffic safety application scenarios we consider are variations of collision avoidance using LTE-based broadcast communication. Our main evaluation criteria are delay and packet loss rate. We present our findings for each scenario and compare the results.

ABSTRACT Internet traffic from a fibre based residential access network is investigated concerning traffic volumes and link load. Also the cost of the services is analyzed. We show that 1 Mbps accesses subscribers maintain high loads, and that the price they pay per GB used is five times higher than the one paid by 100 Mbps access subscribers.

To increase the number of services and applications in the telecommunication networks a new service architecture has been proposed and specified. The consortia that initiated the new service architecture is called Parlay. Since then, there has been a continued development and 3GPP the standardization group for 3G networks, is now cooperating with Parlay. 3GPP and Parlay are together specifying the

... idéer om att även kvinnor, med sina kapaciteter och kunskaper, hade en viktig roll att fylla i helheten [1]. Även om Platon hade goda ... än männen med samma betyg (95% signifikant enligt independent sample t-test), se Tabell V. I kategorin 'MVG' finns inga statistiskt signifikanta ...

Abstract. Vehicular ad-hoc networks (VANETs) offer a large number of new potential applications without relying on significant infrastructure. Many of these applications benefit from multi-hop relaying of information, thus requir- ing a routing protocol. Characteristics unique to ...