The performance of wireless systems could be significantly improved by directional antennas with highly efficient MAC layers and other control protocols and algorithms. One such critical algorithm is neighbor discover...
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The performance of wireless systems could be significantly improved by directional antennas with highly efficient MAC layers and other control protocols and algorithms. One such critical algorithm is neighbor discovery, which establishes links between adjacent neighboring nodes in the network. In this article, we first study the slotted synchronous system and propose a novel neighbor discovery algorithm to address the high collision problem caused by high node density. We then evaluate the performance of neighbor discovery algorithms and extend the results to asynchronous systems. Simulation results show that for the synchronous system, our algorithm consistently shortens the required time for the whole discovery process from that in previous works;for an asynchronous system, our algorithm sheds insight on how to select design parameters.
Tag collision arbitration is considered as one of the critical issues in RFID system design. In order to further improve the identification efficiency of tag anti-collision algorithms in RFID systems, several types of...
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Tag collision arbitration is considered as one of the critical issues in RFID system design. In order to further improve the identification efficiency of tag anti-collision algorithms in RFID systems, several types of dynamic framed slotted ALOHA (DFSA) anti-collision algorithms are analyzed, and a new anti-collision algorithm is proposed. The proposed algorithm has the ability of identifying the time slot distribution which is selected by the tags within a reader's interrogation range in advance. Then the free time slots will be skipped when the reader queries each time slot. Also, the colliding tags will be immediately processed with additional time slots. Simulation results show that the proposed algorithm takes fewer total number of time slots and has a higher efficiency of tag identification compared to the other four DFSA anti-collision algorithms.
The short-time unbiased spectrum estimation (STUSE) algorithm is analyzed and expressions for the mean and variance of the spectrum estimates are derived. The STUSE algorithm deliberately adds biased spectrum estimate...
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The short-time unbiased spectrum estimation (STUSE) algorithm is analyzed and expressions for the mean and variance of the spectrum estimates are derived. The STUSE algorithm deliberately adds biased spectrum estimates in order to yield unbiased estimates and at the same time have excellent spectral leakage suppression capabilities. Computer simulations are presented, verifying the theoretical results and also comparing the STUSE algorithm with the conventional weighted, overlapped, segment averaging (WOSA) method.
A related paper provides an algorithm to compute the reliability of an undirected network. The algorithm exploits the decomposition tree of the network derived from decomposing the network graph into its triconnected ...
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A related paper provides an algorithm to compute the reliability of an undirected network. The algorithm exploits the decomposition tree of the network derived from decomposing the network graph into its triconnected components. This paper extends the algorithm to apply to reliability problems involving directed networks. Details are presented which specialize the algorithm to apply to the problems of 2-terminal communication, transportation flow feasibility, and path-length feasibility.
The maximum robustness design of envelope-constrained filters with uncertain input (ECUI) is formulated as a minimax optimization problem in which the set of feasible filters is characterized by nonsmooth matrix inequ...
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The maximum robustness design of envelope-constrained filters with uncertain input (ECUI) is formulated as a minimax optimization problem in which the set of feasible filters is characterized by nonsmooth matrix inequalities, An efficient designalgorithm is developed to solve this problem by use of a newly developed transformation technique. The attractive feature of this algorithm is that the ECUI filter thus designed can allow for the greatest uncertainty in the input signal while still achieving the acceptable filter performance.
Systems that require reengineering are a fact of life in both the commercial and military arenas. The authors have developed a systematic methodology based on virtual prototyping, with accompanying tools and libraries...
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Systems that require reengineering are a fact of life in both the commercial and military arenas. The authors have developed a systematic methodology based on virtual prototyping, with accompanying tools and libraries, for rapidly upgrading electronic systems.
A rigorous algorithm for computing integer order Bessel functions of the first and second kind with complex arguments is discussed. The algorithm makes use of backward recurrence for computing Bessel functions of the ...
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A rigorous algorithm for computing integer order Bessel functions of the first and second kind with complex arguments is discussed. The algorithm makes use of backward recurrence for computing Bessel functions of the first kind where applicable, and of Hankel's asymptotic expansion for large arguments. The argument is limited only by the ability of the computer to handle large numbers. Orders up to a few thousand have been computed to 13-digit accuracy.< >
As more users subscribe to ATM data services to support their broadband applications, ATM security devices must be employed to ensure protection against eavesdropping, impersonation, unauthorized data modification, an...
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As more users subscribe to ATM data services to support their broadband applications, ATM security devices must be employed to ensure protection against eavesdropping, impersonation, unauthorized data modification, and denial-of-service threats. Because security policies can vary according to site preference or import/export regulations, the ATM Forum's ATM Security Specification, Version 1.0, provides for the negotiation of security parameters. To increase the likelihood for successful negotiation of encryption parameters, the ATM. encryptor must implement multiple algorithms. Such encryptors are called algorithm-agile encryptors. This article describes a prototype ATM encryptor that implements mechanisms for requesting an encryption algorithm, performing end-user and encryptor authentication, and exchanging encryption keys, using the ATM Forum's Security Message Exchange protocol. When used together;these mechanisms provide protection against eavesdropping and impersonation threats.
With the exponential growth of content in recent years, users are primarily interested in obtaining particular content and are not concerned with the host housing the content. By treating content as a first class citi...
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With the exponential growth of content in recent years, users are primarily interested in obtaining particular content and are not concerned with the host housing the content. By treating content as a first class citizen, information-centric networks (ICN) seek to transform the Internet from a host-to-host communication model to a content-centric model. A key component of ICN is to cache content at storage-enabled routers. By caching content at in-network routers, network performance can be improved by delivering content from routers closer to the user and not from the origin servers (content custodians). In this article, we provide an overview of the state-of-the-art cache management and routing policies in ICN. We present a small comparison study of some state-of-the-art algorithms on a real Internet topology to help the reader appreciate how the different strategies compare against one another. Our simulation results demonstrate that it is hard to pick a winner among existing policies. We conclude the article with a discussion of open research questions.
Acoustic signals are often characterized by pitch, timbre, loudness, forms of modulation, and onset/offset instants. These descriptors of sound quality have a close relationship to the instantaneous spectral propertie...
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Acoustic signals are often characterized by pitch, timbre, loudness, forms of modulation, and onset/offset instants. These descriptors of sound quality have a close relationship to the instantaneous spectral properties of the sound waves. The auditory system has developed elegant mechanisms to extract and represent this spectro-temporal information through noise-robust perceptual features. After decades of research, the anatomical organization and functional significance of many of the underlying mechanisms are now becoming understood. Consequently, mathematical descriptions of the various early and central auditory stages have become feasible and functionally relevant, and can be fruitfully used to derive principles underlying time-frequency analysis in the auditory system. Here, the authors review examples of such approaches from their recent efforts to model the early and central stages of the mammalian auditory systems. It is within the hope of this study to better understand the nature of hearing, and to eventually apply these functional principles to designing engineering applications, such as audio coding algorithms that are closely optimized under perceptual criteria, and automatic speech recognition systems that have performance comparable to humans.< >
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