1,721,035 research outputs found
Performance Evaluation of Four Dimensional Signal Sets Matched to the Channel and their Simulation
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Energy Saving Through Traffic Profiling in Self-Optimizing Optical Networks
No full textAn increasing fraction of the electrical energy produced in western countries is being consumed by Internet infrastructure; reducing its energy footprint is therefore of utmost importance for the scalability of the Internet. We address optical transport backbones and propose a novel method to reduce the energy consumed by dynamically adjusting the number of active optical carriers to support the short-term load of the network with a small and controllable margin. This is achieved in a nondisruptive manner that does not interact with routing strategies and does not rely on any specific control plane, but exploits automated traffic profiling and prediction of the well-known circadian traffic cycle. The proposed approach works with both fixed and flexible grid optical networks. We describe a method to automatically learn these patterns and multiple techniques to predict incoming traffic. Furthermore, we present an algorithm that tunes the parameters of the proposed system in order to achieve a target a posteriori probability of causing traffic losses. The behavior of the system is studied, using simulations, under a variety of conditions. Results show that the proposed prediction algorithms can significantly reduce the number of active optical carriers, even in nonoptimal scenarios, while guaranteeing low traffic losses
Measuring IP and TCP Behavior on Edge Nodes with Tstat
No full textField measurements have always been the starting point for network design and planning; however, their statistical analysis beyond simple traffic volume estimation is not so common. In this paper we present and discuss Tstat, a tool for the collection and statistical analysis of TCP/IP traffic, which, in addition to recognized performance figures, infers TCP connection status from traces. Besides briefly discussing its rationale and use, we present part of the performance figures that can be obtained, and we highlight the insight that such figures can give on TCP/IP protocols and the Inter- net, thereby supporting the usefulness of a widespread use of Tstat or similar tools. Analyzing Internet traffic is difficult because a large amount of performance figures can be devised in TCP/IP net- works, but also because many performance figures can be derived only if both directions of bidirectional traffic are jointly considered. Tstat automatically correlates incoming and outgoing packets. Sophisticated statistics, obtained through data correlation between incoming and outgoing traffic, give reliable estimates of the network performance also from the user perspective. Tstat computes over 80 different performance statistics at both the IP and TCP layers, allowing a good insight in the network performance. To support the latter statement, we discuss several of these figures computed on traffic meas- urements performed for a time period equivalent to more than three months spread during the years 2000-2003 on the access link of Politecnico di Torino. Ó 2004 Elsevier B.V. All rights reserved
How Many Cells Should Be Considered to Accurately Predict the Performance of Cellular Networks
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