PURDUE UNIVERSITY
Grant: $54,900 - National Science Foundation - Aug. 2, 2009
50% voted satisfied - 50% voted not satisfied - 2 vote(s) cast
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Award Description: The investigator will construct different statistical models for the general Internet traffic and traffic from one extremely time-sensitive application, Voice over Internet Protocol (VoIP), due to the different traffic generation mechanism: A VoIP call creates a unique ON-OFF traffic process and the superposed VoIP traffic is generated following a call arrival process. On the other hand the general Internet traffic is a superposed packet stream where individual connection can be treated as a marked point process. The statistical models for both types of traffic will reflect the effect of superposition of multiple connections. The number of connections will be an important parameter in all the models under consideration. Stochastic processes theory will be extensively used to create statistical models of the non-linear long range dependent Internet traffic. The investigator will conduct a queueing study for VoIP, using the proposed VoIP traffic model as the arrival process at a queue. The queueing study will not be limited to the tail probabilities, and will provide results for the entire output process to better understand the effect of superposition on queueing behavior. Statistical models of Internet traffic are critical for computer network design and capacity planning purpose. Parsimonious models which accurately capture the Internet traffic properties will assist network engineers to design future networks with the ability to accommodate user traffic growing quickly beyond the scope of what is being observed today. The models will have simple structure that provides intuition and formulas for the traffic statistical properties, and serve as a tractable basis for further mathematical study of the Internet traffic. Because Quality of Service (QoS) criteria for the general Internet traffic can be a little relaxed while VoIP must comply with very strict QoS standards, the queueing study for VoIP will demonstrate how much VoIP traffic a network can support while maintaining the QoS standards. The proposed research requires knowledge in both statistical theory and computation. Students directly involved in the project will gain experience of statistical computing, and learn the knowledge of stochastic processes and queueing theory.
Project Description: The project at this stage has analyzed and obtained the properties of the Internet voice traffic. The project is using a dataset that is a 48-hr collection of VoIP arrival times and headers of 1.315 billion packets from 332,018 calls on a link of the Global Crossing network. It is one of the few publicly described VoIP datasets from a large operational network of the Internet whose traffic consists of a heterogeneous collection of VoIP applications. A comprehensive analysis of the marginal distributions and time dependencies of call-level properties (arrivals, durations, bit-rates, and transmission and silence intervals), and packet-level properties (timestamp accuracy, jitter, and 20-ms packet-counts) has been done. Afterward two models have been constructed based on the results of the statistical analyses to generate packet-level traffic in one direction of a link. One model is semi-empirical and first generates a call-arrival process which provides the times of the first packets of the calls; the packet inter-arrival times for each call are those of a random sample from an empirical database of 277540 semi-calls (packets in one direction of a call). The call-arrival process in the proposed model resembles the process of the actual measurements. PI The property of the actual call-arrival process has been obtained from the data. Also, the complex task of examining the representativeness of the semi-calls has been completed. A second model has been proposed that does not require the use of the actual VoIP traffic data but instead utilizes the established properties of the traffic. The second model is parametric and replaces the semi-call sampling by simulated VoIP calls.
Infrastructure Description: n/a
Jobs Summary: N/A (Total jobs reported: 0)
Project Status: Less Than 50% Completed
This award's data was last updated on Aug. 2, 2009. Help expand these official descriptions using the wiki below.
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