An overview of distributed simulation of discrete event systems and the issues associated with it. Alternative approaches for decomposing the simulation into tasks that can be run on separate ...processors are described, and the potential parallelism associated with certain kinds of decomposition is studied. Existing synchronization algorithms are discussed. An attempt is made throughout to show what decomposition approaches and synchronization algorithms may be appropriate depending on properties of the application and the multiprocessor architecture. Empirical and analytical performance studies are described, where available.< >
The 26 papers in this special issue focus on game theory in communication systems. The papers are grouped in four clusters according to their topics: (1) Physical layer models in wireless ...communications, (2) higher layer and cross-layer issues in wireless communications, (3) wire-line communication networks, and (4) specific topics including peer-to-peer networking, network coding, and network security.
The relative entropy between two Markov transition rate matrices is derived from sample path considerations. This relative entropy is interpreted as a level-2.5 large-deviations action functional. ...That is, the level-two large-deviations action functional for empirical distributions of continuous-time Markov chains can be derived from the relative entropy using the contraction mapping principle.< >
There are N independent machines. Machine i is described by a sequence {X^{i}(s), F^{i}(s)} where X^{i}(s) is the immediate reward and F^{i}(s) is the information available before i is operated for ...the sth lime. At each time one operates exacfiy one machine; idle machines remain frozen. The problem is to schedule the operation of the machines so as to maximize the expected total discounted sequence of rewards. An elementary proof shows that to each machine is associated an index, and the optimal policy operates the machine with the largest current index. When the machines are completely observed Markov chains, this coincides with the well-known Gittins index rule, and new algorithms are given for calculating the index. A reformulation of the bandit problem yields the tax problem, which includes, as a special case, Klimov's waiting time problem. Using the concept of superprocess, an index rule is derived for the case where new machines arrive randomly. Finally, continuous time versions of these problems are considered for both preemptive and nonpreemptive disciplines.
The symbols produced by a finite Markov source are causally encoded so as to be transmitted through a noisy memoryless channel. The encoder is assumed to have channel feedback information and the ...decoder to be causal. The feedback information is shown to be useful in general. Separation results are derived and used to prove that encoding is useless for a class of symmetric channels.
Three infrared absorption lines of the nu5 band of C2H2 diluted by Xe at pressures ranging from 40 to 300 mbar have been recorded at high resolution near 750 cm-1, using a tunable diode-laser ...spectrometer. Their lineshapes have been first analyzed by means of models using either the Dicke narrowing effect or the absorber speed-dependent collisional broadening and shifting. None of these models have given satisfactory results over the full pressure range of the perturber. It is shown that a correct treatment must include both line narrowing effects. We have investigated two possibilities of doing so: a convolution between two profiles corresponding to each effect and a noncorrelated and speed-dependent Rautian profile that we have developed here. The latter lineshape model appears to be the most appropriate. Copyright 1997 Academic Press. Copyright 1997Academic Press
A simple dynamic routing problem Ephremides, A.; Varaiya, P.; Walrand, J.
IEEE transactions on automatic control,
08/1980, Letnik:
25, Številka:
4
Journal Article
Recenzirano
As jobs arrive they have to be routed to one of two similar exponential servers. It is shown that if the queue lengths at both servers are observed then the Optimal decision is to route jobs to the ...shorter queue, whereas if the queue lenths are not observed then it is best to alternate between queues, provided the initial distribution of the two queue sizes is the same. The optimality of these routing strategies is independent of the statistics of the job arrivals.
A Markov-modulated Poisson process (MMPP) is a Poisson process whose rate is a finite Markov chain. The Poisson process is a simple MMPP. An MMPP/M/1 queue is a queue with MMPP arrivals, an infinite ...capacity, and a single exponential server. We prove that the output of an MMPP/M/1 queue is not an MMPP process unless the input is Poisson. We derive this result by analyzing the structure of the non-linear filter of the state given the departure process of the queue. The practical relevance of the result is that it rules out the existence of simple finite descriptions of queueing networks with MMPP inputs.
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