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28
Simple and Efficient Models for Variable Bit Rate MPEG Video Traffic
 Performance Evaluation
, 1995
"... For the performance analysis of ATM networks carrying Variable Bit Rate (VBR) MPEG video sequences there is a need for appropriate video traffic models. In this paper, we discuss Markov chain models for this specific type of traffic with respect to several statistical properties and their ability to ..."
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Cited by 44 (2 self)
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For the performance analysis of ATM networks carrying Variable Bit Rate (VBR) MPEG video sequences there is a need for appropriate video traffic models. In this paper, we discuss Markov chain models for this specific type of traffic with respect to several statistical properties and their ability to predict cell losses at buffers of ATM multiplexers. We intentionally selected a simple model class to check for its appropriateness to model a complex traffic type. The results of this paper show that Markov chain models can be used efficiently for MPEG video traffic under the following conditions. The Group of Pictures (GOP) generation process should be modeled rather than the frame process. If the performance measures depend on the correlation properties of the video traffic the scene process should also be considered in the course of the model development. 1 Introduction In BISDNs on the basis of the ATM, a major part of the traffic will be generated by multimedia sources like teleco...
Network Buffer Requirements of the RateBased Control Mechanism for ABR Services
 in Proc. of IEEE INFOCOM
, 1995
"... In ATM networks congestion control plays an essential role to support different quality of service guarantees for a large variety of traffic types. While for realtime communications, such as CBR and VBR services, a preventive openloop congestion control mechanism is applied, a reactive closedloop ..."
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Cited by 37 (4 self)
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In ATM networks congestion control plays an essential role to support different quality of service guarantees for a large variety of traffic types. While for realtime communications, such as CBR and VBR services, a preventive openloop congestion control mechanism is applied, a reactive closedloop mechanism has been suggested for the ABR service class, which was introduced aiming at data communication applications. This paper presents a performance analysis of the ratebased congestion control mechanism developed by the ATM Forum. Using a differential equation approach for the computation of the evolution of the allowed cell rate and the buffer content during steady state, we derive closedform expressions to estimate the maximum buffer lengths. These expressions can be formulated for steadystate conditions as well as for transient phases. In our approach, scenarios with and without priority for the resource management cells are considered. From numerical examples we conclude that an...
On the Power of NumberTheoretic Operations with Respect to Counting
 IN PROCEEDINGS 10TH STRUCTURE IN COMPLEXITY THEORY
, 1995
"... We investigate function classes h#Pi f which are defined as the closure of #P under the operation f and a set of known closure properties of #P, e.g. summation over an exponential range. First, we examine operations f under which #P is closed (i.e., h#Pi f = #P) in every relativization. We obtain t ..."
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Cited by 32 (9 self)
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We investigate function classes h#Pi f which are defined as the closure of #P under the operation f and a set of known closure properties of #P, e.g. summation over an exponential range. First, we examine operations f under which #P is closed (i.e., h#Pi f = #P) in every relativization. We obtain the following complete characterization of these operations: #P is closed under f in every relativization if and only if f is a finite sum of binomial coefficients over constants. Second, we characterize operations f with respect to their power in the counting context in the unrelativized case. For closure properties f of #P, we have h#Pi f = #P. The other end of the range is marked by operations f for which h#Pi f corresponds to the counting hierarchy. We call these operations counting hard and give general criteria for hardness. For many operations f we show that h#Pi f corresponds to some subclass C of the counting hierarchy. This will then imply that #P is closed under f if and only if ...
SteadyState Analysis of the RateBased Congestion Control Mechanism for
 ABR Services in ATM Networks. Mai
, 1995
"... In ATM network environments, congestion control plays an important role to support different quality of service guaranteesforalargevariety of tra c types. While for realtime communications, like CBR and VBR services, a preventive openloop congestion control mechanism is applied, a reactive closed ..."
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Cited by 26 (6 self)
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In ATM network environments, congestion control plays an important role to support different quality of service guaranteesforalargevariety of tra c types. While for realtime communications, like CBR and VBR services, a preventive openloop congestion control mechanism is applied, a reactive closedloop mechanism has been suggested for the ABR service class, which was introduced mainly for data communications. This paper presents an analysis to evaluate the performance of the ratebased congestion control mechanism developed by theATM Forum. We derive formulae to compute the evolution of the allowed cell rate and the resulting bu er content during steady state. Therefore, we focus on tra c scenarios consisting of single sources as well as of homogeneous mixes of ABR sources. From numerical examples we can conclude that an appropriate setting of the control parameters is important toachieve a reasonable performance of the ratebased control mechanism, especially to obtain low bu er requirements in conjunction with a high utilization of network resources. Furthermore, a strong dependence on the number of active
Logspace and Logtime Leaf Languages
, 1996
"... The computation tree of a nondeterministic machine M with input x gives rise to a leaf string formed by concatenating the outcomes of all the computations in the tree in lexicographical order. We may characterize problems by considering, for a particular "leaf language" Y , the set of all x for whi ..."
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Cited by 25 (2 self)
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The computation tree of a nondeterministic machine M with input x gives rise to a leaf string formed by concatenating the outcomes of all the computations in the tree in lexicographical order. We may characterize problems by considering, for a particular "leaf language" Y , the set of all x for which the leaf string of M is contained in Y . In this way, in the context of polynomial time computation, leaf languages were shown to capture many complexity classes. In this paper, we study the expressibility of the leaf language mechanism in the contexts of logarithmic space and of logarithmic time computation. We show that logspace leaf languages yield a much finer classification scheme for complexity classes than polynomial time leaf languages, capturing also many classes within P. In contrast, logtime leaf languages basically behave like logtime reducibilities. Both cases are more subtle to handle than the polynomial time case. We also raise the issue of balanced versus nonbalanced comp...
Recurrent Multilayer Perceptrons for Identification and Control: The Road to Applications
, 1995
"... : This study investigates the properties of arti#cial recurrent neural networks. Particular attention is paid to the question of how these nets can be applied to the identi#cation and control of nonlinear dynamic processes. Since these kind of processes can only insu#ciently be modelled by conve ..."
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Cited by 21 (3 self)
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: This study investigates the properties of arti#cial recurrent neural networks. Particular attention is paid to the question of how these nets can be applied to the identi#cation and control of nonlinear dynamic processes. Since these kind of processes can only insu#ciently be modelled by conventional methods, di#erent approaches are required. Neural networks are considered to be useful for this purpose due to their ability to approximate a wide class of continuous functions. Among the numerous network structures, especially the recurrentmultilayer perceptron #RMLP# architecture is promising from application point of view. This network architecture has the wellknown properties of multi layer perceptrons and moreover these nets have the ability to incorporate temporal behavior. Departing from the original process description the applicability of RMLPs is investigated and di#erent learning algorithms for this network class are outlined. Furthermore, besides the conventional...
Analysis of a RateBased Control Policy with Delayed Feedback and Variable Bandwidth Availability
, 1996
"... The investigation of feedback controls for telecommunication networks has recently gained considerable interest. The reason is the definition of a new ATM service category, the socalled Available Bit Rate service, whose primary goal is the economical support of applications with vague requirements ..."
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Cited by 20 (5 self)
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The investigation of feedback controls for telecommunication networks has recently gained considerable interest. The reason is the definition of a new ATM service category, the socalled Available Bit Rate service, whose primary goal is the economical support of applications with vague requirements for throughputs and delays. One class of possible feedback controls is formed by the ratebased mechanisms. Feedback from the network switches to the end systems gives users the information necessary to appropriately adjust their transmission rates. This type of control has been investigated to some extent in the existing literature, assuming a constant transmission rate on a bottleneck link. In this paper, we present a discretetime analysis of a feedback control policy, taking into account a bottleneck link capacity that varies according to a general probability distribution. The control policy we look at belongs to the class of explicit rate control mechanisms considered for the Available...
Performance Analysis of the Dual Cell Spacer in ATM Systems
, 1995
"... In this paper we develop an analysis of the socalled Dual Cell Spacer. In contrast to a conventional spacer, which shapes a traffic stream only according to a given Peak Cell Rate, the Dual Cell Spacer takes into account the Peak Cell Rate as well as the Sustainable Cell Rate with the corresponding ..."
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Cited by 20 (7 self)
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In this paper we develop an analysis of the socalled Dual Cell Spacer. In contrast to a conventional spacer, which shapes a traffic stream only according to a given Peak Cell Rate, the Dual Cell Spacer takes into account the Peak Cell Rate as well as the Sustainable Cell Rate with the corresponding Burst Tolerance. The analysis is carried out in the discretetime domain. Performance measures such as the cell rejection probability, the cell delay distribution and the cell interdeparture time distribution are derived. All results are of an exact nature. Numerical examples that compare the performance of the Dual Cell Spacer with that of a conventional spacer show a similar performance in terms of cell delay and cell loss for relatively small values of the Burst Tolerance. Using our analysis, both the Sustainable Cell Rate and the Burst Tolerance, which are used for traffic shaping in the Dual Cell Spacer, can be chosen adequately to achieve a given target cell rejection probability or ...
Analysis of the Generic Cell Rate Algorithm Monitoring ON/OFFTraffic
, 1994
"... This study deals with the enforcement of source parameters in ATM networks. An algorithm for monitoring the cell rate of a connection is the socalled generic cell rate algorithm. At the moment, only peak cell rate policing is standardized, but there are discussions in the standard commissions to in ..."
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Cited by 18 (9 self)
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This study deals with the enforcement of source parameters in ATM networks. An algorithm for monitoring the cell rate of a connection is the socalled generic cell rate algorithm. At the moment, only peak cell rate policing is standardized, but there are discussions in the standard commissions to introduce a second source parameter, the sustainable cell rate in conjunction with a burst tolerance. These source parameters are defined at the physical layer service access point where ATM connections behave like ON/OFFsources due to the preceding cell spacer. In this paper, we present an algorithm to derive the exact cell rejection probability of the generic cell rate algorithm if ON/OFFsources are monitored. This is done by an iterative algorithm based on a discretetime analysis technique. Using the cell rejection probability, the parameters for the monitor algorithm can be chosen to meet desired performance objectives, e.g. the conformance of a connection. Numerical results show that th...
Weak Growing ContextSensitive Grammars
, 1995
"... Well investigated are growing contextsensitive languages (GCSL), i. e. languages defined by grammars that have only growing rules, where the left side of a growing rule is shorter than its right side. GCSL is characterized by quasi growing contextsensitive grammars (QGCSG), i. e. the rules therein ..."
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Cited by 16 (0 self)
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Well investigated are growing contextsensitive languages (GCSL), i. e. languages defined by grammars that have only growing rules, where the left side of a growing rule is shorter than its right side. GCSL is characterized by quasi growing contextsensitive grammars (QGCSG), i. e. the rules therein are growing only with respect to a valuation of all the strings by a homomorphism to natural numbers with addition. In this paper we introduce weak growing contextsensitive grammars (WGCSG), i. e. grammars that are growing with a weighted valuation of all strings, where the weights are the values of a position valuation. Here we evaluate a string by summing up every product of a symbol value with its position value. For every position valuation which does not agree with the beginning of any exponential function, the corresponding class of WGCSGs characterizes CSL, shown by a somehow tricky proof. Such a valuation function is called unsteady. On the other hand all WGCSG related to steady ...