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[26 May 2014] A bachelor student at RTSLAB was awarded the best thesis award from IDA - Simon Andersson. more ...

[31 May 2012] A masters student at RTSLAB was awarded the best thesis award from IDA - Ulf Magnusson. more ...

[27 February 2008] A masters student at RTSLAB was awarded the best thesis award from IDA - Johan Sigholm. more ...

[03 March 2004] A masters student at RTSLAB was awarded the best thesis award from IDA - Tobias Chyssler. more ...

[01 Jul 2003] For second year in a row a masters student at RTSLAB was awarded the best thesis award from SNART - Mehdi Amirijoo. more ...

Master Thesis - Past Projects - Abstract

Optimization of Data Carousels Distributing Interactive TV Based Applications

ID: LITH-IDA-EX--06/048--SE

A common approach for distributing interactive TV based applications is using a mechanism called a data carousel. The data carousel continuously broadcasts all application data while receivers passively wait for data to arrive, this is very similar to how teletext systems work. And, as in teletext systems, this causes delays when an application is waiting for a particular data item to arrive. The carousel layout defines how often and in what order the data items are broadcast, and it is of great interest to adjust the carousel layout in order to minimize data access times. Tools currently available provide little support in creating a good carousel layout, and creating one by hand is a very difficult and complex task. It requires intimate knowledge about how applications will be used and how they will access the application data. The objective of this thesis is to implement a system that automates the task of creating a data carousel layout that maximizes the performance of the applications it delivers. This is achieved using feedback data from receivers running the interactive applications as they are used by the actual end users. In this work, algorithms that analyze this data have been developed and implemented. They create an optimized carousel layout that adapts in real time to changes in user behavior and delivered content. Creating a data carousel layout is a special case of the more general problem of data broadcast scheduling. Previous research on algorithms in this area focused mainly on how to minimize access times by adjusting the broadcast frequency of items according to their size and popularity. This work identifies additional methods that decrease access times even further by also adjusting the relative order of certain items based on how they are accessed, and by adjusting the frequency of items based on prefetching behavior. While the actual deployment of the system was outside of the scope of this thesis, a comprehensive simulation system to verify the functionality has been implemented. During simulation, delays have been reduced to a third compared to an unoptimized carousel, and to less than half compared to optimization based on size and popularity alone.

Keywords: optimization, data carousel, data broadcast scheduling, demand probability

Author(s): Anders Olsson

Contact: Calin Curescu

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