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Active Performance Monitoring for Multimedia ATM Networks

Authors:

Burell A., Oklahoma State University, USA

Papantoni T., University of Alabama, USA

ABSTRACT

We consider multimedia ATM networks with time-varying traffics and topologies. To deal effectively with the time-varying environment, the deployment of traffic and network performance monitoring techniques is necessary for the identification of traffic changes, network failures, and also for the facilitation of protocol adaptations and topological modifications. The objective of the paper is the design, analysis and evaluation of mobile intelligent agents that implement effective performance monitoring techniques, while capturing the dynamics inherent in the multimedia environments. Towards this objective, a core sequential algorithm which depicts the functionality and operations of the network performance monitoring techniques is adopted. Specific forms of the algorithm are used for the identification of networks failures. For a given network topology, the location of the minimum necessary set of agents for complete network and traffic “visibility” is be specified via identifiability methods.

Key Words. Mulitmedia ATM Networks, Algorithmic Monitoring, Failure Recognition, Identifiability.

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Decision Feedback Differentially Detected GMSK Signals in the Presence of ACI and Nonlinearities

Authors:

Mathiopoulos T., Athens Observatory, Greece

Toor S. J., Wireless Locat Technologies Group, Seattle, USA

ABSTRACT

The effects on the performance of difFerentially detected Gaussian Minimum Shift Keying (GMSK) signals operated in the presence of adjacent channel interference (ACl), modulator impairments, amplifier nonlinearities and additive white Gaussian noise (AWGN) is investigated. By means of computer simulation, the bit error rate (BER) performance of 1and 2-bit conventional and decision feedback differentially detected (C-DD and DF-DD) GMSK systems in the presence of static and Rayleigh faded ACl is obtained. It is found that the best performance is achieved by the 2-bit DF-DD receiver and has resulted in BER performance improvements for the static ACl channel and error floor reductions for the Rayleigh faded ACl channel.

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Loss Volume in Continuous Flow Models: Fast Simulation and Sensitivity Analysis via IPA

Authors:

Wardi Y., Georgia Institute of Technology, USA

Melamed B., Rutgers University, USA

ABSTRACT

This paper defines a class of uid- ow models, called Continuous Flow Models (CFMs), representable as DEDS (Discrete Event Dynamic System) models. The CFM class is motivated by emerging high-speed packet-based telecommunications networks for which traditional queueing simulations at the packet level are prohibitively costly in time and space, or simply infeasible. In contrast, CFM-based uid- ow networks hold the promise of fast simulation for applications ranging from network design to network control. The paper studies the loss volume metric of a basic CFM in some detail. This metric is easily converted to loss probabilities { an important ingredient in quality of service (QoS) metrics for modern telecommunications networks. The paper further performs sensitivity analysis of CFMs via IPA derivatives of the loss volume as function of buffer size, as well as service rate and arrival rate parameters. Simple formulas for these derivatives are derived and shown to be amenable to real-time computation. The formulas have a broad applicability dueto their nonparametric (distribution-free) nature, a fact that makes them potentially suitable for real-time control applications in telecommunications networks.

Key words. CFM, Continuous Flow Models, High-Speed Networks, IPA, Loss Metrics. Topics addressed. Discrete event systems.

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A Cybernetic Model of Computerisation of the Cultural Heritage

Authors:

F. Filip, Nat. Institute for R&D in Informatics, Romania

D. Donciulescu, Nat. Institute for R&D in Informatics, Romania

C. Filip, Nat. Institute for R&D in Informatics, Romania

ABSTRACT

An e-Europe for all should include the facilitation of European citizens to the cultural heritage of Europe and Mediterranean area. This paper proposes a vision for a transition to complex systems combining IT organisations and cultural institutions. It describes the impact and limits and proposes a preliminary cybernetic model to study the relationship between the organisations implied.

Keywords: business processes, computer networks, cultural heritage, discrete time systems, information technology, library, museum, social impact, simulation.

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Energy Considerations in Mobile ad-hoc Networks

Authors:

Tragoudas S., Southern Illinois University, USA

ABSTRACT

The nodes of a mobile ad hoc network run on local energy sources. This paper identifies energy related problems in network management and routing which when appropriately tackled increase the reliability of the network. A new routing method for improved quality of service is presented that takes into consideration the energy life of each node. We also present a methodology for recharging the energy sources of the mobile nodes with minimal impact on the network's reliability.

Key Words. Wireless communication, mobile networks, network reliability, routing protocols

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