Flow Level QoE of Video Streaming in Wireless Networks

The Quality of Experience (QoE) of streaming service is often degraded by frequent playback interruptions. To mitigate the interruptions, the media player prefetches streaming contents before starting playback, at a cost of delay. We study the QoE of streaming from the perspective of flow dynamics. First, a framework is developed for QoE when streaming users join the network randomly and leave after downloading completion. We compute the distribution of prefetching delay using partial differential equations (PDEs), and the probability generating function of playout buffer starvations using ordinary differential equations (ODEs) for CBR streaming. Second, we extend our framework to characterize the throughput variation caused by opportunistic scheduling at the base station, and the playback variation of VBR streaming. Our study reveals that the flow dynamics is the fundamental reason of playback starvation. The QoE of streaming service is dominated by the first moments such as the average throughput of opportunistic scheduling and the mean playback rate. While the variances of throughput and playback rate have very limited impact on starvation behavior.Comment: 14 page

Analysis of Buffer Starvation with Application to Objective QoE Optimization of Streaming Services

Our purpose in this paper is to characterize buffer starvations for streaming services. The buffer is modeled as an M/M/1 queue, plus the consideration of bursty arrivals. When the buffer is empty, the service restarts after a certain amount of packets are \emph{prefetched}. With this goal, we propose two approaches to obtain the \emph{exact distribution} of the number of buffer starvations, one of which is based on \emph{Ballot theorem}, and the other uses recursive equations. The Ballot theorem approach gives an explicit result. We extend this approach to the scenario with a constant playback rate using T\`{a}kacs Ballot theorem. The recursive approach, though not offering an explicit result, can obtain the distribution of starvations with non-independent and identically distributed (i.i.d.) arrival process in which an ON/OFF bursty arrival process is considered in this work. We further compute the starvation probability as a function of the amount of prefetched packets for a large number of files via a fluid analysis. Among many potential applications of starvation analysis, we show how to apply it to optimize the objective quality of experience (QoE) of media streaming, by exploiting the tradeoff between startup/rebuffering delay and starvations.Comment: 9 pages, 7 figures; IEEE Infocom 201

Comparison of LTE eMBMS and DVB-NGH mobile TV solutions from an energy consumption perspective

International audienceThe power demand of future wireless networks is predicted to dramatically increase. This energy consumption issue, if unaddressed, will restrict the roll-out of many new services. Based on this fact, we try in this paper to study and compare the energy consumption of the most popular mobile TV delivery solutions: LTE eMBMS and DVB-NGH. We study the energy consumption in a region where Mobile TV is delivered by a standalone LTE network and a standalone DVB-NGH transmitter or by a cooperative LTE/DVB network. By cooperation we mean that the mobile TV coverage is ensured by DVB in the region surrounding a broadcasting tower and by LTE otherwise. Our work is a simulation one and can be used as an offline study that enables the operators to configure their networks towards a Green Mobile TV delivery. Results shows that the cooperation will decrease the power consumption of at least one of the cooperative operators (LTE and/or DVB) and thus it will certainly decrease the overall power consumption in the service region for a high level Green Mobile TV solution

Performance Evaluation of Dual Carrier Feature in the Uplink of HSPA+ Systems

International audienc

Flow-Level QoE of Video Streaming in Wireless Networks

International audienceThe Quality of Experience (QoE) of streaming service is often degraded by frequent play-back interruptions. To mitigate the interruptions, the media player prefetches streaming contents before starting playback, at a cost of initial delay. We study the QoE of streaming from the perspective of flow dynamics. Firstly, a framework is developed for QoE when streaming users join the network randomly and leave after downloading completion. We model the distribution of prefetching delay using partial differential equations (PDEs), and the probability generating function of playout buffer starvations using ordinary differential equations (ODEs) for constant bit-rate (CBR) streaming. The explicit form starvation probabilities and mean start-up delay are obtained by use of a matrix function approach. Secondly, we extend our framework to characterize the throughput variation caused by opportunistic scheduling at the base station, and the playback variation of variable bit-rate (VBR) streaming. Our study reveals that the flow dynamics is the fundamental reason of playback starvation. The QoE of streaming service is dominated by the first moments such as the average throughput of opportunistic scheduling and the mean playback rate. While the variances of throughput and playback rate have very limited impact on starvation behavior in practice

Ostreopsis spp.: Morphology, proliferation and toxic profile in the North-West of Agadir (North Atlantic Ocean).

The distribution of benthic Ostreopsis species is poorly known in the Moroccan coasts. The current study is aiming to investigate: i) the distribution of Ostreopsis spp. cells on macroalgae and in the seawater column of the Cape Ghir area (North-West of Agadir) during the summer season of Ostreopsis from July 15 to November 17, 2020; ii) the toxic profile at the level of the three matrices (benthic Ostreopsis attached to macroalgae, Ostreopsis in the water column and mussels) via chemical analysis using mass spectrometry. A taxonomic study of Ostreopsis spp. was carried out using the light and inverted optical microscopes. Chemical analysis showed the presence of ovatoxins (OvTX-A and OvTX-B) in Ostreopsis samples in low quantities, in the order of fg.cell −1 and at levels below the limit of quantification (0.04 g.mL −1) in mussels. Morphological observations showed that the cells were ovoid and flattened, large, and ventrally pointed with a dorsoventral diameter (DV) and width (W) of 57- and 33-, respectively, and a dorsoventral/anteroposterior diameter (DV/AP) of about 3.23

FANTASTIC-5G:Flexible air interface for scalable service delivery within wireless communication networks of the 5th generation

5th generation mobile networks will have to cope with a high degree of heterogeneity in terms of services, mobility, number of devices and so on. Thus, diverse and often contradicting key performance indicators need to be supported, but having multiple radio access technologies for multi-service support below 6 GHz will be too costly. FANTASTIC-5G will develop a new multi-service air interface through a modular design. To allow the system to adapt to the anticipated heterogeneity, some properties need to be pursued, like simplicity, flexibility, scalability, versatility, efficiency and future proofness. Based on these properties, a selected set of use cases and link and network design will be presented. The paper will also comprise validation and system level simulations through some indicative results and will conclude with the overall impact to 5G standardisation