sujet de thèse à Orange Labs

> Bonjour,
>
> L'équipe "Traffic and Resource Management" de l'Orange Labs R&D annonce
> un poste de thèse sur le sujet "Performance evaluation of source coding
> for streaming services in wireless networks". Le descriptif est le
> suivant:
>
> Sujet de thèse: Performance evaluation of source coding for streaming
> services in wireless networks
>
> Descriptif:
> Wireless networks are increasingly carrying video traffic. A major
> difficulty of live video streaming in wireless networks is the variability
> in user data rates. Data rates in wireless networks depend strongly on
> user location and environment. As such, a constant feedback to the source
> is necessary in order to appropriately adapt the sending rate. At the
> radio link, retransmissions for packet losses and acks increase congestion
> at a link which already suffers from limited capacity. Further, in the
> case of multicast or broadcast transmissions such as TV, multiple
> transmissions of varying rates create redundancy and additional congestion
> at the radio link.
>
> Digital fountain-like source coding with appropriate buffer management and
> bandwidth sharing has been proposed to address the issue of congestion
> control with feedback. Such transmission mechanisms seem to be a natural
> fit for the wireless medium. The source sends a stream of coded packets,
> whose order is not important. Once the wireless destination has received
> a sufficient number of packets in order to decode, it signals to the
> source or the base station (in case of multicast or broadcast) an
> indication that it has received the data.
>
> Considering the significant differences between wireless and wired
> networks, application of such source coding is not entirely
> straightforward. The role of the base station as a simple relay or smart
> scheduler may need to be redefined. Furthermore, latency requirements of
> video delivery may limit expected gains. Evaluation of the performance
> gains of source coding in the wireless environment, and video applications
> in particular is crucial to a better understanding of such a system of
> delivery.
>
> The objective of the proposed thesis will be the evaluation of performance
> gains of source coding techniques for live streaming delivery in wireless
> networks. While performance analysis of source coding techniques for
> data has been initiated, many question remain concerning fairness
> policies, scheduling policies in intermediate nodes, and latency
> requirements for streaming applications, in addition to the applicability
> of such mechanisms in wireless networks. A major portion of the thesis
> will be devoted to the performance analysis of the impact of digital
> fountain-like source coding techniques on network congestion, with the aim
> of characterizing gains, in both a live video streaming scenario and a
> wireless environment. The results will potentially uncover system
> parameters that are crucial to performance gains. The performance study
> will naturally lead to the proposals of mechanisms for better design.
>
> The evaluation of performance gains will begin with an appropriate model
> of the system that includes the random nature of traffic. The
> specificities of wireless networks will be included as seen fit. The
> study will then proceed on two fronts: analysis of the applicability of
> source coding without explicit congestion control to the wireless
> scenario; and the analysis of such a source coding mechanism for streaming
> applications with latency requirements.
> The thesis will begin with a bibliographical study of the state of the
> art. Once a proper understanding the concepts at play is established,
> depending on the abilities of the student, analysis or simulations will be
> carried out. This phase is expected to last for a long duration, and
> will be followed by the characterization of design principles and new
> mechanisms for delivery of live streaming services over wireless networks.
>
> It is important that the candidate be knowledgeable on networks in
> general, and wireless networks in particular, including congestion control
> schemes. The candidate must be very comfortable developing simulations
> and have a strong interest and aptitude for applied probability.
>
> The thesis work will be carried out at Orange Labs R & D, in Paris,
> France. Note that this is a fully funded Ph.D position.
>
> Contact: Nidhi Hegde, Orange Labs
> nidhi.hegde@orange-ftgroup.com
>
>
>
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