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Publications by Type: Undergrad Theses (Bachelor, Diplom, and Master Theses) and Study Projects

Performance Evaluation of Resend-based Error Resilience in IPTV Services
Citation key B-PERBERIS-10
Author Balarajah, Balamuhunthan
Year 2010
Address Berlin, Germany
Month December
Note This work was co-supervised with Prof. Alexander Raake
School Technische Universität Berlin
Abstract The rapid growth of IPTV services results in a raised resource demand with respect to server and network capacity. For the success of such services, the ability to deliver a high service level to customers is an essential aspect of IPTV services, which is neccessary to ensure a high customer satisfaction and Quality of Experience (QoE). However, as overloaded systems can negatively affect the provided service quality, service providers must account for degradations of service quality and their influence on QoE in network planning and dimensioning. In particular, network impairments such as packet loss, delay and jitter can significantly degrade the video quality. To improve the delivered quality, recovery mechanisms such as FEC, ARQ are needed and typically deployed. Over 20 of the world’s leading service providers—including Deutsche Telekom—have selected the Microsoft Mediaroom (MSTV) platform to provide their digital TV services. The MSTV system uses a retransmission mechanism (ARQ) to improve the delivered quality. Retransmission requests are issued by the Set-top Box (STB) that receives the IPTV content. Corresponding responses are served by a retransmission cache server. This thesis investigates the ARQ of MSTV because of the practical relevance of this system. Concretely, in this thesis, we empirically study the characteristics of IPTV traffic as well as the behavior of a MSTV Set-top Box (STB) to gain insights in the deployed ARQ recovery mechanism. We use an edge based measurement setup to capture traffic traces close to the STB to be able to replicate the network conditions the STB was facing. Those traces contain impairments as injecting packet losses with and without jitter. This measurement study leads us to find statistical distributions for measured IPTV network properties such as jitter, packet inter-arrival time and properties of the video content. The obtained statistical distributions are used to generate synthetic traces. Synthetic and measured traces are then applied in our trace driven simulator for the purpose of performance evaluations of ARQ mechanisms. As the ARQ implementation details of the STB are proprietary, we implement three active recovery mechanisms with different complexities and evaluate their performance in the context of IPTV using a simulation study. The simulations are based on captured traces as well as synthetic traces. This study considers different network scenarios by analyzing the impact of delay, jitter and uniform/bursty packet loss. Moreover, the buffer management parameters like the buffer depth and influences of different parametrizations of the ARQ mechanisms are investigated. Finally, a comparision of the measured STB traffic with our simulation results provides insights into the ARQ implementation in the STB.
Bibtex Type of Publication Diplomarbeit
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