No. 4 (2007)
Published:
2007-12-30
ARTICLES FROM THIS ISSUE
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Traffic splitting in MPLS networks – a hierarchical multicriteria approach
Abstract
In this paper we address a new hierarchical multicriteria routing model associated with a two-path traffic splitting routing method in MPLS networks whereby the bandwidth required by a given node-to-node traffic flow is divided by two disjoint paths. The model has two levels of objective functions and several constraints. An algorithmic approach is presented for calculating non-dominated solutions and selecting good compromise solutions to this problem. Also a number of computational experiments are presented.
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A note on the computation of ordered supported non-dominated solutions in the bi-criteria minimum spanning tree problems
Abstract
This paper presents a new procedure for computing the set of supported non-dominated solutions of bi-criteria minimum spanning tree problems in ordered manner. The procedure is based on the systematic detection of edges which must be replaced in one efficient solution to obtain the adjacent one, in the criteria space. This new approach avoids solving unnecessary problems and makes use of previous computations.
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Determining hop-constrained spanning trees with repetitive heuristics
Abstract
The hop-constrained minimum spanning tree problem is the problem of determining a rooted spanning tree of minimum cost in which each path from the root node to any other node contains at most H hops or edges. This problem relates to the design of centralized tree networks with quality of service requirements (in telecommunications) and has a close relation with other tree problems. In this paper we investigate the adaptation of some well-known "repetitive" heuristics used for the capacitated minimum spanning tree problem to the hop-constrained minimum spanning tree problem and investigate some simple look ahead mechanisms for enhancing the quality of a savings heuristic. Computational results for a set of benchmark tests with up to 80 nodes are presented.
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Application of bioinformatics methods to recognition of network threats
Abstract
Bioinformatics is a large group of methods used in biology, mostly for analysis of gene sequences. The algorithms developed for this task have recently found a new application in network threat detection. This paper is an introduction to this area of research, presenting a survey of bioinformatics methods applied to this task, outlining the individual tasks and methods used to solve them. It is argued that the early conclusion that such methods are ineffective against polymorphic attacks is in fact too pessimistic.
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A general framework of agent-based simulation for analyzing behavior of players in games
Abstract
In this paper, we give a general framework of agent-based simulation for analyzing behavior of players in various types of games. In our simulation model, artificial adaptive agents have a mechanism of decision making and learning based on neural networks and genetic algorithms. The synaptic weights and thresholds characterizing the neural network of an artificial agent are revised in order that the artificial agent obtains larger payoffs through a genetic algorithm. The proposed framework is illustrated with two examples, and, by giving some simulation result, we demonstrate availability of the simulation analysis by the proposed framework of agent-based simulation, from which a wide variety of simulation settings can be easily implemented and detailed data and statistics are obtained.
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Artificial adaptive agent model characterized by learning and fairness in the ultimatum games
Abstract
This paper examines the result of the experimental research on the ultimatum games through simulation analysis. To do so, we develop agent-based simulation system imitating the behavior of human subjects in the laboratory experiment by implementing a learning mechanism involving a concept of fairness. In our agent-based simulation system, mechanisms of decision making and learning are constructed on the basis of neural networks and genetic algorithms.
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Application of open multi-commodity market data model on the communication bandwidth market
Abstract
In the paper the market model for balancing communication bandwidth trade (BCBT) is analyzed in the form of multi-commodity market data model (M3). The distinguishing feature of BCBT model is that it assumes that market players can place buy offers not only for isolated network resources – inter-node links, but also for end-to-end network paths of predefined capacity, that is, every offer concerns a point-to-point bandwidth connection between a pair of specified locations in a communication network. The model enables effective balancing of sell and buy offers for network resources in a way which maximizes global economic welfare. The open multi-commodity market data model provides efficient and clear mechanisms, which support the environment of auctions and multi-commodity exchanges, especially when the trade is constrained by the infrastructure resources. Thus the model may be used in designing open information systems for market balancing and clearing in the context of multicommodity trade in various network infrastructure sectors.
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Economic disparities among regions in Japan and the problem of the spread of information and communication equipment in the countryside
Abstract
Japan’s government believed that the development of ICT networks and penetration of information and communications equipment in the countryside reduce the economic and population disparities among regions. Since the latter half of the 90s, some local governments built "intelligent facilities" equipped with ICT network so as to foster the information and communications industry in their area as part of regional "informatization policy". However, "intelligent buildings" failed to attract information and communication companies, economic disparities among regions are in fact widening, while the macro economy is recovering and expanding. Main points are the contents of the regional informatization policy and the effect on the development of ICT networks and the information and communication industry. As "economy of concentration" works more in the information and communications economy, the development of ICT networks and related industries would concentrate economic power in urban areas. At present, it is essential for the regional informatization policy to develop information and telecommunications infrastructure that addresses the needs of residents who lack access to information, and to implement careful information literacy education for residents.
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Possibility for the application of publications analysis to evaluation of research institutes
Abstract
This study looks at the possibility of using publications analysis, which has been used by companies as a basic survey method for formulating publications strategies, as a quantitative index for evaluating researches conducted by national universities. The study also describes the reality of public outreach toward Japanese society, being carried out by research institutes such as universities, through publications analysis.
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Analysis of propagation of orthogonally polarized supermode in straight and curved multicore microstructured fibres
Abstract
We analyze the dependence of radiation loss, effective indices and difference of the effective indices of the two modes with similar field distribution propagating in dual-core microstructured fibres as well as their polarization behavior on fibre parameters (air hole diameter, hole separation, distance between guiding cores) and fibre bending. Optimization of the parameters of such fibres using as vector bend sensors is considered.
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Impact of the duration of speech sequences on speech quality
Abstract
This paper describes simulations of speech sequences transmission for intrusive measurement of voice transmission quality of service (VTQoS) in the environment of IP networks. The aim of the simulations was to investigate the impact of the different durations of speech sequences on speech quality from the jitter rate and packet loss point of view in IP networks. The ITU-T G.729 and ITU-T G.723.1 encoding schemes were used for the purpose of the simulations. The assessment of speech quality was realized by means of perceptual evaluation of speech quality (PESQ) algorithm. A comparison of the impact of different durations of speech sequences on speech quality and determination of the optimal duration of speech sequence for measurements of speech quality in telecommunication networks, is the aim of this paper.
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Optimum receiver performance of TH-PPM ultra wideband system in multiple user interference
Abstract
This paper demonstrates optimum receiver performance in terms of bit error rate (BER) for time hopping pulse position modulation (TH-PPM) ultra wideband (UWB) system in multiple user interference environment for indoor radio communication. Equal gain combining and selective gain combining have been demonstrated in terms of ideal RAKE (ARAKE), selective RAKE (SRAKE) and partial RAKE (PRAKE) receiver performances. The recently accepted IEEE 802.15.3a model of the UWB channel has been used to describe UWB propagation in indoor environment. Two channel scenarios named CM-1 and CM-3 for IEEE 802.15.3a channel model have been investigated principally. Finally, this paper concludes with an approximation of equivalence of number of fingers in SRAKE and PRAKE receivers as well as an indication of SNR gains achievable as the RAKE finger number is increased, espe- cially with multiple user interference (MUI), for a 16.6 Mbit/s UWB system.
