As a basic requirement of live peer-to-peer multimedia streaming sessions, the streaming playback rate needs to be strictly
enforced at each of the peers. In real-world peer-to-peer streaming sessions with very large scales, the number of streaming
servers for each session may not be easily increased, leading to a limited supply of bandwidth. To scale to a large number
of peers, one prefers to regulate the bandwidth usage on each of the overlay links in an optimal fashion, such that limited
supplies of bandwidth may be maximally utilized. In this paper, we propose a decentralized bandwidth allocation algorithm
that can be practically implemented in peer-to-peer streaming sessions. Given a mesh P2P topology, our algorithm
explicitly reorganizes the bandwidth of data transmission on each overlay link, such that the streaming bandwidth demand
is always guaranteed to be met at any peer in the session, without depending on any a priori knowledge of available peer
upload or overlay link bandwidth. Our algorithm is especially useful when there exists no or little surplus bandwidth supply
from servers or other peers. It adapts well to time-varying availability of bandwidth, and guarantees bandwidth supply
for the existing peers during volatile peer dynamics. We demonstrate the effectiveness of our algorithm with in-depth
simulation studies.
We address the question: What is the best way to construct a mesh overlay topology for multimedia content distribution, such that the highest streaming rate can be achieved? We model overlay capacity correlations as linear capacity constraints (LCC) and propose a distributed algorithm that constructs an overlay mesh which incorporates heuristically inferred linear capacity constraints. Our simulations results confirm the accuracy of representing overlays using our LCC model and show the LCC-overlay achieving substantial improvement in achievable flow rate.
Multicasting is a natural paradigm for streaming live multimedia to
multiple end receivers. Since IP multicast is not widely deployed, many application-layer multicast protocols have been proposed. However, all of these schemes focus on the construction of multicast trees, where a relatively small number of links carry the multicast streaming load, while the capacity of most of the other links in the overlay network remain unused. In this paper, we propose CodedStream, a high-bandwidth live media distribution system based on end-system overlay multicast. In CodedStream, we construct a k-redundant multicast graph (a directed acyclic graph) as the multicast topology, on which network coding is applied to work around bottlenecks. Simulation results have shown that the combination of k-redundant multicast graph and network coding may indeed bring significant benefits with respect to improving the quality of live media at the end receivers.
In different areas of applications such as education, entertainment, medical surgery, or space shuttle launching, distributed visual tracking systems are of increasing importance. In this paper we describe the design, implementation and evaluation of OmniTrack, a distributed omni-directional visual tracking system, developed at the University of Illinois at Urbana-Champaign, with an Adaptive Middleware Architecture as the core of the system. With respect to both operating systems and network connections, adaptation is of fundamental importance to the tracking system, since it runs in an environment with large performance variations and without support of Quality of Service guarantees.
To support real-time multimedia applications in wireless packet networks, it is an essential challenge to provide seamless quality of service (QoS) to mobile users. In this paper, we address the problem of real-time multimedia multicast in cellular networks, and present our solution to avoid large QoS fluctuations during handoffs. Specifically, during a multicast session, a mobile host may experience varying packet delay, delay jitter, and channel error when it moves from one cell to another. It is thus desirable that these location-dependent QoS parameters appear as seamless as possible to mobile hosts. We present protocols to achieve a degree of transmission synchronization among multiple cells, so that the delays and delay jitters of each packet to all subscribing mobile hosts do not vary substantially. In addition, we apply Forward Error Correction technique to recover the QoS-mandatory packets from wireless channel errors. We show through analysis and simulation that the mobile hosts will experience brief, smooth, and low packet loss rate handoffs.
KEYWORDS: Optical tracking, Control systems, Detection and tracking algorithms, Internet, Algorithm development, Fuzzy logic, Systems modeling, Algorithms, Visual process modeling, Video
In current end systems, multiple flexible, complex and distributed applications concurrently share and compete both end system resource and transmission bandwidth of heterogeneous multi-protocol networks, especially the Internet. Our objective is to enable adaptation awareness in these applications to fully cope with the dynamics in resource availability over the heterogeneous Internet, as well as fluctuations in QoS requirements of the applications themselves. In this paper, we present the theoretical and practical aspects of a Task Control Model implemented in the middleware layer, which applies control theoretical approaches to utilize measurement-based samples monitored in the network traffic, as well as resource and QoS demand dynamics observed in the end systems.
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