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IEEE 1st AESS European Conference on Satellite Telecommunications (ESTEL)

作者： Neji, Najett de Lacerda, Raul Azoulay, Alain Letertre, Thierry Outtier, Olivier SUPELEC DRE F-91192 Gif Sur Yvette France

ISBN: (纸本)9781467346887;9781467346863

In the last decade, the aeronautical authorities expressed their need to develop a new system for aeronautical radio-communications. The L-band Digital Aeronautical Communication System (L-DACS) is the part of the future system that will be operating in a part of the aeronautical L-band (960-1164 MHz), already occupied by a large number of radio-frequency legacy systems. This paper aims at studying the L-DACS impact on a legacy system, the Distance Measuring Equipment (DME), under two critical situations. Such topics are fundamental in aeronautics, as any communication or radionavigation dysfunction may endanger flight and passengers security. Some obtained results will be used for the L-DACS standardization and its specifications finalization. For the first scenario (air-to-air scenario), we propose a deterministic algorithm to compute the interference level in the frequency domain. Since this seems to be insufficient for the second scenario (co-site scenario), we develop a time-frequency approach to analyze the interference using an aeronautical RFC test-bed that we implemented at Supelec.

关键词： order of interference Legacy systems Coexistence Frequency-domain analysis dimethyl ether deterministic algorithms Astronautics Communication Research L-band flight Radio navigation Radiocommunication continental

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Scheduled Channel Access Using Geographical Classification

Scheduled Channel Access Using Geographical Classification

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International Conference on Computing, Networking and Communications (ICNC)

作者： Masilamani, Ashok N. Garcia-Luna-Aceves, J. J. Univ Calif Santa Cruz Dept Comp Engn Santa Cruz CA 95064 USA

ISBN: (纸本)9781467300094

Geographical Classification Multiple Access (GCMA) is introduced for scheduled channel access in large wireless networks. GCMA uses the geo-spatial coordinates of nodes, together with their transmission and interference ranges, to define collision-free transmission schedules using deterministic distributed algorithms. These algorithms require each node to know only the geo-spatial coordinates of its immediate neighbors to derive correct transmission schedules, even in the presence of hidden terminals. The transmission frames in GCMA consist of the minimum number of time slots needed to avoid multiple access interference, given the transmission and interference ranges of the nodes. GCMA is compared against representative examples of alternative approaches to medium access control;the results of the simulation experiments show that GCMA attains higher packet-delivery ratio and better goodput with end-to-end delay comparable to the other protocols.

关键词： access protocols delays deterministic algorithms distributed algorithms interference suppression multi-access systems radio access networks radiofrequency interference scheduling wireless channels

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Contention Resolution in a Non-Synchronized Multiple Access Channel

Contention Resolution in a Non-Synchronized Multiple Access ...

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IEEE 27th International Parallel and Distributed Processing Symposium (IPDPS)

作者： De Marco, Gianluca Kowalski, Dariusz R. Univ Salerno I-84084 Fisciano SA Italy Univ Liverpool Liverpool L69 3BX Merseyside England

ISBN: (纸本)9780769549712

Multiple access channel is a well-known communication model that deploys properties of many network systems, such as Aloha multi-access systems, local area Ethernet networks, satellite communication systems, packet radio networks. The fundamental aspect of this model is to provide efficient communication and computation in the presence of restricted access to the communication resource: at most one station can successfully transmit at a time, and a wasted round occurs when more than one station attempts to transmit at the same time. In this work we consider the problem of contention resolution in a multiple access channel in a realistic scenario when up to k stations out of n join the channel at different times. The goal is to let at least one station to transmit alone, which results in successful delivery of the message through the channel. We present three deterministic algorithms: two of them working under some constrained scenarios, and achieving asymptotically optimal time complexity Theta(k log(n/k)), while the third general algorithm accomplishes the goal in time O(k log n log log n).

关键词： Multiple access channel Contention resolution deterministic algorithms Distributed algorithms

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Approximate inference in Bayesian networks using binary probability trees

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INTERNATIONAL JOURNAL OF APPROXIMATE REASONING 2011年第1期52卷 49-62页

作者： Cano, Andres Gomez-Olmedo, Manuel Moral, Serafin Univ Granada Dept Comp Sci & Artificial Intelligence Higher Tech Sch Comp Sci & Telecommun E-18071 Granada Spain

The present paper introduces a new kind of representation for the potentials in a Bayesian network: binary probability trees. They enable the representation of context-specific independences in more detail than probability trees. This enhanced capability leads to more efficient inference algorithms for some types of Bayesian networks. This paper explains the procedure for building a binary probability tree from a given potential, which is similar to the one employed for building standard probability trees. It also offers a way of pruning a binary tree in order to reduce its size. This allows us to obtain exact or approximate results in inference depending on an input threshold. This paper also provides detailed algorithms for performing the basic operations on potentials (restriction, combination and marginalization) directly to binary trees. Finally, some experiments are described where binary trees are used with the variable elimination algorithm to compare the performance with that obtained for standard probability trees. (C) 2010 Elsevier Inc. All rights reserved.

关键词： Bayesian networks inference Approximate computation Variable elimination algorithm deterministic algorithms Probability trees

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A Simulation-Based Approach for Control Design of Uncertain UAVs

A Simulation-Based Approach for Control Design of Uncertain ...

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51st IEEE Annual Conference on Decision and Control (CDC)

作者： Capello, Elisa Tempo, Roberto Politecn Torino Dept Mech & Aerosp Engn Corso Duca Abruzzi 24 I-10129 Turin Italy Politecn Torino CNR IEIIT I-10129 Turin Italy

ISBN: (纸本)9781467320665

The objective of this paper is the development of a randomized Linear Quadratic Regulator (LQR) algorithm via gradient-based methods for Unmanned Aerial Vehicles (UAVs) subject to uncertainty to cope with different operating conditions. A controller gain is synthesized using a Lyapunov approach dealing with a formation of two mini-UAV systems in the classical Leader/Wingman configuration. The advantages of the proposed technique over the existing deterministic methods for control design are as follows: (i) the uncertainty structure is not defined a priori and (ii) one Lyapunov inequality is approximately solved at each iteration of the algorithm, so that the number of inequalities does not grow with the number of uncertain parameters. The main contribution of this paper is to demonstrate that the proposed sequential algorithm provides a randomized controller which stabilizes the uncertain system. This probabilistic technique is then validated with an extensive a posteriori analysis. The final result is to show that the UAV reaches the desired altitude without an additional Proportional-Integral-Derivative (PID) channel, and therefore tuning of the controller gains is avoided.

关键词： Lyapunov methods approximation theory autonomous aerial vehicles control system synthesis deterministic algorithms gradient methods iterative methods linear quadratic control probability random processes randomised algorithms stability uncertain systems

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Subsumption and indexing in constraint query languages with linear arithmetic constraints

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Annals of Mathematics and Artificial Intelligence 1993年第3-4期8卷 315-343页

作者： Srivastava, Divesh Computer Sciences Department University of Wisconsin-Madison 53706 WI United States

Bottom-up evaluation of a program-query pair in a constraint query language (CQL) starts with the facts in the database and repeatedly applies the rules of the program, in iterations, to compute new facts, until we have reached a fixpoint. Checking if a fixpoint has been reached amounts to checking if any "new" facts were computed in an iteration. Such a check also enhances efficiency in that subsumed facts can be discarded, and not be used to make any further derivations in subsequent iterations, if we use Semi-naive evaluation. We show that the problem of subsumption in CQLs with linear arithmetic constraints is co-NP complete, and present a deterministic algorithm, based on the divide and conquer strategy, for this problem. We also identify polynomial-time sufficient conditions for subsumption and non-subsumption in CQLs with linear arithmetic constraints. We adapt indexing strategies from spatial databases for efficiently indexing facts in such a CQL: such indexing is crucial for performance in the presence of large databases. Based on a recent algorithm by C. Lassez and J.-L. Lassez for quantifier elimination, we present an incremental version of the algorithm to check for subsumption in CQLs with linear arithmetic constraints. © 1993 J.C. Baltzer AG, Science Publishers.

关键词： Checking arithmetic deterministic algorithms Indexing Constraint visual databases data base language flexible AC transmission systems Linear iterative methods Database

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Brief Announcement: Beeping a Time-Optimal Leader Election 18

Brief Announcement: Beeping a Time-Optimal Leader Election

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37th ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing (PODC)

作者： Dufoulon, Fabien Burman, Janna Beauquier, Joffroy Univ Paris Saclay Univ Paris Sud CNRS LRI Orsay France

ISBN: (纸本)9781450357951

The beeping model is an extremely restrictive broadcast communication model that relies only on carrier sensing. In this model, we solve the deterministic leader election problem with an asymptotically optimal round complexity. Using this result, we obtain an asymptotically optimal randomized leader election algorithm for anonymous networks, as well as improved algorithms for symmetry-breaking and communication primitives. The techniques that we introduce give a new insight as to how local constraints on the exchangeable messages can result in efficient algorithms, when dealing with the beeping model.

关键词： distributed algorithms leader election beeping model time complexity deterministic algorithms

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TESTING EQUALITIES OF MULTIPLICATIVE REPRESENTATIONS IN POLYNOMIAL-TIME

TESTING EQUALITIES OF MULTIPLICATIVE REPRESENTATIONS IN POLY...

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34th Annual Symposium on Foundations of Computer Science (FOCS 93)

作者： GE, GQ UNIV CALIF BERKELEY DEPT MATHBERKELEYCA 94720

ISBN: (纸本)0818643706

For multiplicative representations /spl Pi//sub i=1//sup k//spl alpha//sub i//sup n(i)/ and /spl Pi//sub j=1//sup l//spl beta//sub j//sup m(j)/ where /spl alpha//sub i/, /spl beta//sub j/ are non-zero elements of some algebraic number field K and n/sub i/, m/sub j/ are rational integers, we present a deterministic polynomial time algorithm that decides whether /spl Pi//sub i=1//sup k//spl alpha//sub i//sup n(i)/ equals /spl Pi//sub j=1//sup l//spl beta//sub j//sup m(j)/. The running time of the algorithm is polynomial in the number of bits required to represent the number field K, the elements /spl alpha//sub i/, /spl beta//sub j/ and the integers n/sub i/, m/sub j/.

关键词： deterministic algorithms polynomial matrices testing equalities multiplicative representations polynomial time nonzero elements algebraic number field rational integers deterministic polynomial time algorithm

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A low-complexity navigation algorithm for a scalable autonomous firefighting vehicle

A low-complexity navigation algorithm for a scalable autonom...

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5th Student Conference on Research and Development

作者： Harwayne-Gidansky, Jared Sudano, Michael Cooper Union Adv Sci & Art Dept Elect & Comp Engn New York NY 10003 USA Cooper Union Adv Sci & Art Dept Mech Engn New York NY 10003 USA

ISBN: (纸本)9781424414697

The design and implementation of a low cost, scalable autonomous vehicle that detects, approaches, and extinguishes a heat source while avoiding obstacles in its path is presented. This design was implemented by using a low-complexity, deterministic algorithm. The algorithm, in addition to being scalable, has minimal hardware requirements. The completed robot is a proof of concept prototype, to demonstrate the reliability of using this algorithm in autonomous robots for combating a variety of fires.

关键词： control systems deterministic algorithms mechatronics mobile robot motion-planning robot sensing systems

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Approximations for Minimum Connected Sensor Cover

Approximations for Minimum Connected Sensor Cover

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32nd IEEE INFOCOM Conference

作者： Wu, Lidong Du, Hongwei Wu, Weili Li, Deying Lv, Jing Lee, Wonjun Univ Texas Dallas Dept Comp Sci Richardson TX 75080 USA Harbin Inst Technol Shenzhen Grad Sch Shenzhen Peoples R China Shenzhen Key Lab Internet Informat Collaborat Shenzhen Peoples R China Renmin Univ China Sch Informat Beijing 100872 Peoples R China Korea Univ Dept Comp Sci & Engn Seoul South Korea

ISBN: (纸本)9781467359467

Given a requested area, the Minimum Connected Sensor Cover problem is to find a minimum number of sensors such that their communication ranges induce a connected graph and their sensing ranges cover the requested area. Several polynomial-time approximation algorithms have been designed previously in the literature. Their best known performance ratio is O(r ln n) where r is the link radius of the sensor network and n is the number of sensors. In this paper, we will present two polynomial-time approximation algorithms. The first one is a random algorithm, with probability 1 - epsilon, producing an approximation solution with performance ratio O(log(3) n log log n), independent from r. The second one is a deterministic approximation with performance ratio O(r), independent from n.

关键词： approximation theory computational complexity deterministic algorithms graph theory wireless sensor networks

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