Vasilis' publications

Ph.D. Dissertation

``Performance Analysis and Pricing in Broadband Networks''. Ph.D. Dissertation, Dept. of Computer Science, University of Crete, December 1997. Advisor: Prof. Costas Courcoubetis

Effective procedures for performance analysis and pricing are important for controlling the use and dimensioning of broadband networks. These procedures must be accurate, efficient, and take into account the technological characteristics of broadband networks.

In this dissertation we apply and evaluate, for real traffic, the many sources asymptotic and the related effective bandwidth definition, and show how they can be used to clarify the effects on the link's performance of the time scales of traffic burstiness, of the traffic mix, of the link parameters (capacity and buffer), and of traffic control mechanisms, such as traffic smoothing. Furthermore, we use the many sources asymptotic to simultaneously capture the cell scale and burst scale effects on the buffer overflow probability at an ATM (Asynchronous Transfer Mode) link with a small buffer that multiplexes a large number of periodic on-off sources. In addition to giving the correct expression of the overflow probability for very small buffers, we give a new qualitative description of how overflow occurs for such buffers.

We investigate usage-based pricing schemes for services with open loop control that are based on bounds of the effective bandwidth. These include time-volume schemes that involve two measurements (the duration of a connection and the total volume transferred), and two schemes that involve measurements in distinct time intervals, smaller than the duration of a connection: pricing with renegotiation and the virtual bucket scheme. Finally, we present an approach to pricing and resource sharing for ABR services with the following three features: (i) prices are adjusted according to the demand, (ii) users declare the price per unit of time according to which they will be charged, and (iii) resource sharing is based on effective bandwidths.

Our experiments are performed for link capacities and buffer sizes that will be used in broadband networks, and involve MPEG-1 compressed video with various contents, Internet Wide Area Network (WAN) traffic, and modeled voice traffic.

Whole thesis: [ .ps.gz (530 Kbytes)], [or here, .ps.gz (530 Kbytes)]

My defense was held on November 27, 1997. For those curious, here is my thesis writing progress.


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