Talks and Activities
Abstract - The explosive growth of content-on-the-move, such as video streaming to mobile devices, has propelled research on multimedia broadcast and multicast schemes. Multi-rate transmission strategies have been proposed as a means of delivering layered services to users experiencing different downlink channel conditions. In this presentation, we consider random linear network coding for its inherent reliability features and study two encoding approaches, which are appropriate for layered services. We derive packet error probability expressions and use them as performance metrics in the formulation of resource allocation frameworks. The aim of these frameworks is both the optimization of the transmission scheme and the minimization of the number of broadcast packets on each downlink channel, while offering service guarantees to a predetermined fraction of users. Our proposed frameworks are adapted to the LTE stack and the integrated eMBMS technology. We focus on the delivery of a video service based on the H.264/SVC standard and demonstrate the advantages of layered network coding over multi-rate transmission. Furthermore, we establish that the choice of both the network coding technique and the resource allocation method play a critical role in the footprint of a service, as determined by the quality of each received video layer.
Ioannis ChatzigeorgiouVTC 2014 Fall, Vancouver, Canada, September 2014
Abstract - We consider a system of two nodes transmitting to an access point on quasi-static Rayleigh fading channels. We use signal-to-noise ratio (SNR) thresholds to characterize the requirements of each node, in terms of throughput and reliability, and we study their impact on outage probability. Given the average quality of the uplink channels, we formulate conditions on the SNR thresholds for decode-and-forward cooperation to be beneficial; that is, for nodes to experience an improvement in their outage probabilities if they switch from non-cooperative to cooperative transmission. We derive analytical bounds and propose tight approximations, which can be applied by the nodes to make decisions in favor or against cooperation.
Andrew Jones, Ioannis Chatzigeorgiou, Andrea TassiCSNDSP 2014, Manchester, UK, July 2014
Abstract - Fountain codes are gradually being incorporated into broadcast technologies, such as multimedia streaming for 4G mobile communications. In this paper, we investigate the capability of existing fountain-coded schemes to recover a fraction of the source data at an early stage and progressively retrieve the remaining source packets as additional coded packets arrive. To this end, we propose a practical Gaussian elimination decoder, which can recover source packets "on-the-fly". Furthermore, we introduce a framework for the assessment of progressive packet recovery, we carry out a performance comparison of the investigated schemes and we discuss the advantages and drawbacks of each scheme.