146 research outputs found
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
Multipath streaming: fundamental limits and efficient algorithms
We investigate streaming over multiple links. A file is split into small
units called chunks that may be requested on the various links according to
some policy, and received after some random delay. After a start-up time called
pre-buffering time, received chunks are played at a fixed speed. There is
starvation if the chunk to be played has not yet arrived. We provide lower
bounds (fundamental limits) on the starvation probability of any policy. We
further propose simple, order-optimal policies that require no feedback. For
general delay distributions, we provide tractable upper bounds for the
starvation probability of the proposed policies, allowing to select the
pre-buffering time appropriately. We specialize our results to: (i) links that
employ CSMA or opportunistic scheduling at the packet level, (ii) links shared
with a primary user (iii) links that use fair rate sharing at the flow level.
We consider a generic model so that our results give insight into the design
and performance of media streaming over (a) wired networks with several paths
between the source and destination, (b) wireless networks featuring spectrum
aggregation and (c) multi-homed wireless networks.Comment: 24 page
Energy-efficient wireless communication
In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters
The design and analysis of a corporate data network supporting a real-time clinical data application
In this study a design is proposed for a corporate, data network supporting real-time data applications. The proposed network incorporates both Local Area Network and Wide Area Network technologies to form a system capable of supporting a variety of applications. Multimedia software, like desktop video conferencing, IP telephony, and video streaming are becoming more pervasive. Since multimedia applications depend on active human involvement and perception, they are commonly referred to as real-time. The content of real-time applications relies on the timely and consistent delivery of information. If real-time applications experience any variation in information delivery, usually referred to as jitter, the result is unacceptable application performance. However, real-time applications are not solely limited to traditional multimedia. Interactive client-server based data applications also fall into this category. This project will specifically focus on the performance of a real-time clinical application, which has become predominant in the healthcare industry. To support the implementation of the proposed network, empirical data was gathered from system testing. Testing involved comparing the performance of a real-time application on the proposed design, against the current architecture. The result found that the proposed data network design reduced transport latency, allowing the real-time application to perform more efficiently
On the trade-off between quality of experience and energy efficiency in a heterogeneous cellular network
Two important issues in the current mobile cellular networks are: Firstly, the traffic on the internet has shifted from the file downloads to the video and audio streaming, secondly, the energy efficiency of cellular networks is a major concern. Particularly, the ever-increasing number of users with the exponential growth of high-data-rate traffic demand creates new challenges for wireless access providers. On the one hand, service providers want to satisfy the growing mobile data traffic demands but on the other hand, they try to reduce the operational costs and carbon emissions by decreasing the energy consumption. In this work, we explicitly quantify the tradeoff between quality of experience (QoE) and energy efficiency in a heterogeneous cellular network. We investigate an optimal resource on-off switching framework that minimizes the energy consumption of a heterogeneous cellular network while satisfying a desired level of quality of user experience. Considering an ON/OFF bursty arrival process, we introduce recursive equations to obtain the buffer starvation probability, as a QoE metric, of a mobile device (MD) for streaming services. The MD is in the coverage area of a femtocell base station (FBS) which is implemented at the cell edge of a macrocell base station (MBS). The buffer starvation event occurs whenever the mobile device’s buffer gets empty, and after each such event, the media player of the MD restarts the service after a certain amount of packets are prefetched (start-up or initial buffering delay). Our results have the potential to reduce carbon emissions of cellular networks by reducing the energy consumption throughout the network, while guaranteeing a target starvation probability to mobile users
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