Martin Ellis
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PhD Research

My PhD research focused on improving our understanding of residential broadband networks, and the effect of these networks on real-time services such as Internet video and IPTV. This involved measurement, analysis, and modelling of real-time traffic. Some of the data I collected is available for download. Using this data, I also evaluated FEC performance over residential links. More information on this work can be found here.

I defended my thesis in October 2012; the abstract reads:

Video streaming applications are now commonplace among home Internet users, who typically access the Internet using DSL or Cable technologies.

However, the effect of these technologies on video performance, in terms of degradations in video quality, is not well understood. To enable continued deployment of applications with improved quality of experience for home users, it is essential to understand the nature of network impairments and develop means to overcome them.

In this dissertation, I demonstrate the type of network conditions experienced by Internet video traffic, by presenting a new dataset of the packet level performance of real-time streaming to residential Internet users. Then, I use these packet level traces to evaluate the performance of commonly used models for packet loss simulation, and finding the models to be insufficient, present a new type of model that more accurately captures the loss behaviour. Finally, to demonstrate how a better understanding of the network can improve video quality in a real application scenario, I evaluate the performance of forward error correction schemes for Internet video using the measurements. I show that performance can be poor, devise a new metric to predict performance of error recovery from the characteristics of the input, and validate that the new packet loss model allows more realistic simulations.

For the effective deployment of Internet video systems to users of residential access networks, a firm understanding of these networks is required. This dissertation provides insights into the packet level characteristics that can be expected from such networks, and techniques to realistically simulate their behaviour, promoting development of future video applications.

The following publications are directly related to my PhD work: