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17
A Theory of Deterministic Queuing Systems for the Internet
, 2003
"... is bounded from below if there is a number M such that s #S. The completeness axiom states that every nonempty subset of R that is bounded from below has a greatest lower bound. We will call it infimum of and denote it by inf . For example the closed and open intervals [a, and (a, b) ha ..."
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is bounded from below if there is a number M such that s #S. The completeness axiom states that every nonempty subset of R that is bounded from below has a greatest lower bound. We will call it infimum of and denote it by inf . For example the closed and open intervals [a, and (a, b) have the same infimum, which is a.Now,ifS contains an element that is smaller than all its other elements, this element is called minimum of and is denoted by minS. Note that the minimum of a set does not always exist. For example, (a, b) has no minimum since a/# (a, b). On the other hand, if the minimum of a set exists, it is identical to its infimum. For example, min[a, b]1 nf[a, b] a. One easily shows that every finite nonempty subset of R has a minimum. Finally, let us mention that we will often use the notation to denote infimum (or, when it exists, the minimum). For example, a b =min{a, b}.IfS is empty, we adopt the convention that inf =+#. If f is a function from to R,
Applicationspecific workload shaping in multimediaenabled personal mobile devices
 In Proc. of the 4th International Conference on Hardware Software Codesign
, 2006
"... Today, most personal mobile devices (e.g. cell phones and PDAs) are multimediaenabled and support a variety of concurrently running applications such as audio/video players, word processors and web browsers. Mediaprocessing applications are often computationally expensive and most of these devices ..."
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Today, most personal mobile devices (e.g. cell phones and PDAs) are multimediaenabled and support a variety of concurrently running applications such as audio/video players, word processors and web browsers. Mediaprocessing applications are often computationally expensive and most of these devices typically have 100 – 400 MHz processors. As a result, the userperceived application response times are often poor when multiple applications are concurrently fired. In this paper we show that by using applicationspecific dynamic buffering techniques, the workload of these applications can be suitably “shaped ” to fit the available processor bandwidth. Our techniques are analogous to traffic shaping which is widely used in communication networks to optimally utilize network bandwidth. Such shaping techniques have recently attracted a lot of attention in the context of embedded systems design (e.g. for dynamic voltage scaling). However, they have not been exploited for enhanced schedulability of multiple applications, as we do in this paper.
MultiPeriod Resource Allocation at System Edges  Capacity Management in a MultiProvider MultiService Internet
 In Proceedings of IEEE Conference on Local Computer Networks (LCN 2001), http://www.kom.etechnik.tudarmstadt.de
, 2001
"... The Internet consists of a variety of interconnected heterogeneous networks managed by independent providers. At the edges between two networks resources are allocated. In this paper, we present a framework and taxonomy for problems at these edges like admission control and provider selection; we ca ..."
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The Internet consists of a variety of interconnected heterogeneous networks managed by independent providers. At the edges between two networks resources are allocated. In this paper, we present a framework and taxonomy for problems at these edges like admission control and provider selection; we call them multiperiod resource allocation problems at system edges (MPRASE). We look at several problem incarnations of this framework and show that many of those problems including wellknown problems in the are of networking are sub or dual problems of each other and that it is useful to treat them in an integrated fashion. 1
Minplus System Theory Applied to Communication Networks
 in Proc. MTNS’02, South
"... Network Calculus is a set of recent developments, which provide a deep insight into flow problems encountered in networking. It can be viewed as the system theory that applies to computer networks. Contrary to traditional system theory, it relies on maxplus and minplus algebra. In this paper, we ..."
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Network Calculus is a set of recent developments, which provide a deep insight into flow problems encountered in networking. It can be viewed as the system theory that applies to computer networks. Contrary to traditional system theory, it relies on maxplus and minplus algebra. In this paper, we show how a simple but important fixedpoint theorem (residuation theorem in minplus algebra) can be successfully applied to a number of problems in networking, such as window flow control, multimedia smoothing, and bounds on loss rates.
Buffer Schemes for VBR Video Streaming over Heterogeneous Wireless Networks
, 2009
"... With the coexistence of different wireless networks, which exhibit largely different bandwidth and coverage characteristics, much interest has been involved in integrating these networks to support smooth and efficient multimedia services. In this paper, we present an analytical framework for varia ..."
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With the coexistence of different wireless networks, which exhibit largely different bandwidth and coverage characteristics, much interest has been involved in integrating these networks to support smooth and efficient multimedia services. In this paper, we present an analytical framework for variablebitrate (VBR) video streaming in a twotier wireless network with VBR channels. We derive the expected number of jitters and average buffering delay during video playback as measures of system performance. Our objective is to discover heterogeneous networking attributes that may influence the streaming performance, in terms of the tradeoff between jitter frequency and buffering delay. Through experimenting with a wide range of fixed, separate, and jointly optimal jitterrecovery buffering schemes, based on buffering delay, buffered data, and buffered playback duration, we quantify the benefit of incorporating user location information in streaming over heterogeneous wireless networks.
Layer thickness in congestioncontrolled scalable video
"... We address the problem of the proper choice of the thickness of preencoded video layers in congestioncontrolled streaming applications. While congestion control permits to distribute the network resources in a fair manner among the different video sessions, it generally imposes an adaptation of th ..."
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We address the problem of the proper choice of the thickness of preencoded video layers in congestioncontrolled streaming applications. While congestion control permits to distribute the network resources in a fair manner among the different video sessions, it generally imposes an adaptation of the streaming rate when the playback delay is constrained. This can be achieved by adding or dropping layers in scalable video along with efficient smoothing of the video streams. The size of the video layers directly drives the convergence of the congestion control to the stable state. In this paper, we derive bounds on both the encoding rates of the video layers that depend on the prefetch delay that can be used for stream smoothing. We then discuss the practical scheduling aspects related to the transmission of layered video when delays are constrained. We finally describe an implementation of the proposed scheduler and we analyze its performance in NS2 simulations. We show that it is possible to derive a mediafriendly rate allocation for layered video in different transmission scenarios, and that the proper choice of the layer thickness improves the average video quality when the prefetch delay is constrained.
Joint Playback Delay and Buffer Optimization in Scalable Video Streaming
, 2007
"... Abstract—This paper addresses the problem of the transmission of scalable video streams to a set of heterogeneous clients through a common bottleneck channel. The packet scheduling policy is typically crucial in such systems that target smooth media playback at all the receivers. In particular, the ..."
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Abstract—This paper addresses the problem of the transmission of scalable video streams to a set of heterogeneous clients through a common bottleneck channel. The packet scheduling policy is typically crucial in such systems that target smooth media playback at all the receivers. In particular, the playback delays and the transmission strategy for the packets of the different layers have to be chosen carefully. When the same video is sent simultaneously to multiple clients that subscribe to different parts of the stream, the playback delay cannot be jointly minimized for all the clients. We therefore propose delay optimization strategies along with low complexity solutions for a fair distribution of the delay penalty among the different receivers. Once the delays are selected, we show that there exists a unique scheduling solution that minimizes the buffer occupancy at all the receivers. We derive an algorithm for computing the optimal sending trace, and we show that optimal scheduling has to respect the order of the packets in each media layer. Interestingly enough,
Date ii Approval Page
, 2003
"... This thesis presents the design and implementation of the application program interface for the second generation CiNIC platform. CiNIC is a coprocessor architecture that offloads network system calls from a host PC to an FPGAbased embedded system. Application software running on the host PC interc ..."
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This thesis presents the design and implementation of the application program interface for the second generation CiNIC platform. CiNIC is a coprocessor architecture that offloads network system calls from a host PC to an FPGAbased embedded system. Application software running on the host PC intercepts networking system calls and uses the CiNIC API to pass these system calls across a shared memory structure to the coprocessor. The CiNIC platform provides many interesting research opportunities, including the ability to implement functions in a mix of hardware and software. Additionally, this thesis presents a scholarly review of hardware/software codesign. This emerging field focuses on achieving a heterogeneous system design from a unified hardware/software engineering effort. Such an approach shows promise for reducing system design time and for minimizing system cost while maximizing performance. Many experts in this field envision a future where a designer fully specifies a complete system by using only a highlevel description language and then uses hardware/software codesign tools to automatically partition and compile the system into hardware and software components.
Streaming
"... We study the optimal streaming of variable bitrate (VBR) video over a random VBR channel. The goal of a streaming application is to enable the successful decoding of each video object before its displaying deadline is violated. Hence, we define the main performance metric of a streaming system as t ..."
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We study the optimal streaming of variable bitrate (VBR) video over a random VBR channel. The goal of a streaming application is to enable the successful decoding of each video object before its displaying deadline is violated. Hence, we define the main performance metric of a streaming system as the probability of uninterrupted video presentation, or jitterfree probability. Previous literature has described solutions to estimate the jitterfree probability by assuming either independence in the encoded data process or simplistic channel models. In this work, we present a novel analytical framework, which requires only some basic statistical information of an arbitrary VBR channel, to bound the probability of jitterfree playout under the constraint of initial playout delay and receiver buffer size. Both the infinite and finite buffer cases are considered. This technique is then applied to investigate streaming over a wireless system modeled by an extended Gilbert channel with ARQ transmission control. Experimental results with MPEG4 VBR encoded video demonstrates that the proposed analysis derives close bounds to the actual system performance. Finally, we show that the proposed analysis provides a theoretical foundation to quantify the tradeoffs between the initial playout delay, the receiver buffer size, and the jitterfree probability for a general class of VBR streaming over random VBR channels. Index Terms EDICS: 5STRM; multimedia streaming, performance modeling, playout delay, receiver buffering, playout interruption
Basic Minplus and Maxplus Calculus
, 2002
"... In this chapter we introduce the basic results from Minplus that are needed for the next chapters. Maxplus algebra is dual to Minplus algebra, with similar concepts and results when minimum is replaced by maximum, and infimum by supremum. As basic results of network calculus use more minplus alg ..."
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In this chapter we introduce the basic results from Minplus that are needed for the next chapters. Maxplus algebra is dual to Minplus algebra, with similar concepts and results when minimum is replaced by maximum, and infimum by supremum. As basic results of network calculus use more minplus algebra than maxplus algebra, we present here in detail the fundamentals of minplus calculus. We briefly discuss the care that should be used when max and min operations are mixed at the end of the chapter. A detailed treatment of Min and Maxplus algebra is provided in [26], here we focus on the basic results that are needed for the remaining of the book. Many of the results below can also be found in [11] for the discretetime setting. 3.1 Minplus Calculus In conventional algebra, the two most common operations on elements of Z or R are their addition and their multiplication. In fact, the set of integers or reals endowed with these two operations verify a number of well known axioms that define algebraic structures: (Z,+,×) is a commutative ring, whereas (R,+,×) is a field. Here we consider another algebra, where the operations are changed as follows: addition