12:45PM, Thursday, January 20th 2005.
Gates 104

Towards a more Dependable Internet:
Understanding Failures in the Core and Overcoming Interference in the Wireless Edge

Athina Markopoulou
Stanford University

About the talk:
Due to technical, economic and social factors, the Internet is becoming the ubiquitous communication infrastructure, carrying all types of applications and inter-connecting various edge-networks.  Although significant progress has been made in improving the quality of service (QoS) and reliability of this infrastructure, there still exist several challenges, depending on the environment. In this talk, I will address two current major challenges: failures in the backbone and interference in the wireless edge. 
In the core of the Internet, IP backbone networks provide today excellent QoS (in terms of delay, jitter and loss), thanks to available spare capacity and sound engineering practices. However, various failures or at below the IP layer, can potentially result in loss of IP connectivity, reduce available capacity and potentially disrupt packet forwarding. In the first part of the talk, I will present a study of failures, based on routing data collected over a seven-month period from the Sprint IP backbone network. Failures are classified based on their probable causes and their key characteristics, such as the frequency and duration, are analyzed.
In the second part of the talk, I will turn my attention to the edge of the network, and in particular to the challenging wireless last-hop. I will focus on the increasingly popular media streaming applications over interference-limited wireless links (e.g. for hand-held devices or home-entertainement systems). We are seeking to optimally control the power at the transmitter and the playout scheduling at the receiver, so as to minimize the power consumption and maximize the media quality. We formulate the problem using a dynamic programming approach, study the structural properties of the optimal solution and develop justified heuristics, which achieve significant performance gains over benchmark systems.
Parts of this work were done in collaboration with colleagues from Sprint ATL (for the 1st part) and with Y. Li,  N. Bambos and J. Apostolopoulos (for the 2nd part).

About the speaker:
Athina Markopoulou is a postdoctoral researcher in the Department of Electrical Engineering at Stanford University. She received her Diploma from the National Technical University of Athens, and her M.S. and Ph.D. degress from Stanford University. She has also been at Sprint ATL, as a postdoctoral member of the technical staff.