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Mark C. Sinclair: Abstracts

Some of the papers on this page are available in gzip-ed PostScript. They should be unpacked after downloading using GNU gunzip. Download gzip for Unix (tar file) or MSDOS.

List of Titles


2000

Dimensioning All-optical Dual-homing Hierarchical Multi-ring Networks with Various Connectivities

Proestaki, A. & Sinclair, M.C.
Proc. Second Intl Workshop on the Design of Reliable Communication Networks (DRCN2000), Munich, Germany, April 2000

This paper presents a dimensioning approach tailored to hierarchical dual-homing multi-ring architectures with and without wavelength converters. Analytical lower bounds based on cutsets are applied in order to allocate the traffic to the individual rings efficiently, as well as to estimate the number of required fibres per ring. The use of these bounds also facilitates the evaluation of the proposed methods. The effect of using a hierarchical fibre distribution, which allocates a larger number of fibres in more heavily loaded rings, is studied. Further, the impact of topology and network connectivity on wavelength and hardware requirements is investigated considering various multi-ring topologies.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Design and Dimensioning of Dual-homing Hierarchical Multi-ring Networks

Proestaki, A. & Sinclair, M.C.
IEE Proceedings Communications v147 n2 April 2000 pp.96-104

A network design study employing multiple interconnected rings which exploit the merits of ring topologies is presented. Near-optimal dual-homing structures are obtained using a novel partition, construct & perturb (PCP) network design method that considers both total ring length and intra-ring traffic. In order to address survivability issues, two bi-connected hierarchical topology schemes are identified, depending on the selection of the interconnecting ring nodes. A routing algorithm that attempts to minimise the maximum flow on the rings, specifically designed for dual-homing structures, is described, which aims for both lower capacity and more balanced solutions than shortest-path routing. The PCP design method is shown to give both better results than an earlier heuristic for various network sizes and demand patterns, and close to the optimal solutions obtained by an integer-linear programming formulation for small problems. Dimensioning of networks is also performed, and the effects of interconnection strategy on total ring length, the ratio of intra-ring to total traffic, overall capacity and average path length of different topologies are discussed.

Evolving User Profiles to Reduce Internet Information Overload

Pagonis, J. & Sinclair, M.C.
Proc. Intl. Conf. on Recent Advances in Soft Computing 2000, Leicester, UK, June 2000

This paper discusses the use of Evolving Personal Agent Environments as a potential solution to the problem of information overload as experienced in habitual Web surfing. Some first experimental results on evolving user profiles using speciating hybrid GAs, the reasoning behind them and support for their potential application in mobile, wireless and location aware information devices are also presented.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Node-Pair Encoding Genetic Programming for Optical Mesh Network Topology Design

Sinclair, M.C.
in Corne, D.W., Oates, M.J. & Smith, G.D. (Ed.), Telecommunications Optimization: Heuristic and Adaptive Techniques, Wiley, 2000, Ch.6, pp.99-114

Two variants of a new node-pair encoding genetic programming (GP) approach for optical mesh network topology design are presented. In addition, a new variant of the earlier connected-nodes encoding is described. Experimental work on 15- and 20-node networks demonstrates that both GP approaches can almost match the design quality of bit-string genetic algorithms, particularly for the larger network size investigated. (This paper is an expanded version of one given at GECCO-99.)


1999

Minimum Cost Wavelength-path Routing and Wavelength Allocation Using a Genetic-algorithm/Heuristic Hybrid Approach

Sinclair, M.C.
IEE Proceedings Communications v146 n1 February 1999 pp.1-7

Minimum cost wavelength-path routing and wavelength allocation of multiwavelength all-optical transport networks using a genetic-algorithm (GA)/ heuristic hybrid approach is described. A cost model is adopted which incorporates a dependency on link wavelength requirements. The hybrid algorithm developed uses an object-oriented representation of networks, and incorporates four operators: path mutation, single-point crossover, reroute and shift-out. In addition, an operator-probability adaptation mechanism is employed to improve operator productivity. Experimental results from seven fifteen-node test networks, obtained using a tool for optical network optimisation, modelling and design (NOMaD), suggest the GA/heuristic hybrid approach provides superior results compared to three recent wavelength-allocation heuristics, except when the network cost depends most heavily on wavelength requirement.

Interconnection Strategies for Dual-homing Multi-ring Networks

Proestaki, A. & Sinclair, M.C.
Proc. 16th International Teletraffic Conference (ITC-16), Edinburgh, UK, June 1999, pp.169-181

The design of large-scale networks adopting a cluster-based approach (interconnection of multiple sub-networks) promises to achieve scalable and expandable networks. The key objective is to make efficient use of network resources, whilst providing bi-connected topologies for increased survivability. We focus on rings as the sub-networks, due to their attractive features. Near-optimal dual-homing multi-ring networks are obtained employing a network design method which considers both ring length and intra-ring traffic. The networks constructed are dimensioned by employing a traffic routing algorithm tailored to dual-homing ring properties. Two possible inherently-hierarchical interconnection schemes are investigated, some of their network properties are explored, and they are compared against `hyper-cluster', a non-hierarchical scheme. We also employ a simple method to estimate the complexity of the network hardware required which distinguishes between the equipment used for intra-ring and inter-ring traffic. Empirical results comparing our two schemes, in terms of switching and transmission capacity, are assessed and the impact of topology on identifying cost-effective networks is discussed.

This paper is available by request in gzip-ed PostScript.

Wavelength Routing in All-optical Dual-homing Hierarchical Multi-ring Networks

Proestaki, A. & Sinclair, M.C.
Proc. European Conference on Networks and Optical Communications - Core Networks and Network Management (NOC'99), Delft, The Netherlands, June 1999, pp.52-59

The design of large-scale networks adopting a clustered-based approach, in particular interconnection of multiple sub-networks, combined with wavelength division multiplexing technology, promises scalable and expandable structures. This paper focuses on wavelength-path routing in resilient hierarchical multi-ring architectures. A novel dimensioning approach is presented, where the path selection depends mainly on the number of rings traversed, aiming to keep the wavelength requirement minimum, while reducing the network hardware cost in terms of switching ports. Cutset-based analytical lower bounds tailored to multi-ring networks are employed to facilitate evaluation of the proposed method. Empirical results obtained for structures adopting different interconnection schemes reveal that the topology is a critical factor for both the wavelength and hardware requirements.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Co-evolutionary Agents for Telecommunication Network Restoration

Shami, S.H. & Sinclair, M.C.
Proc. Recent Advances in Soft Computing'99, Leicester, UK, July 1999, pp.146-151

A novel system of simple mobile software agents is described which, in the event of node or span failure in an arbitrary transport network, quickly spread out through reproduction, cooperate with other agents and gather useful restoration information on the way. On encountering their destinations, or other critical situations, they return to the affected nodes in real-time. The algorithm is capable of handling multiple span failures or up to one node failure at a given time and provides ample restoration information within one second.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Ant Colony Optimisation for Virtual-Wavelength-Path Routing and Wavelength Allocation

Navarro Varela, G. & Sinclair, M.C.
Proc. Congress on Evolutionary Computation (CEC'99), Washington DC, USA, July 1999, pp.1809-1816

Ant Colony Optimisation (ACO) is applied to the problem of routing and wavelength-allocation in a multi-wavelength all-optical virtual-wavelength-path routed transport network. Three variants of our ACO algorithm are proposed: local update (LU), global update/distance (GU/D) and global update/occupancy (GU/O). All three extend the usual practice that ants are attracted by the pheromone trail of ants from their own colony: in our work, the artificial ants are also repelled by the pheromone of other colonies. Overall, the best ACO variant, GU/O, provides results that approach those of an earlier problem-specific heuristic on small- and medium-sized networks.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Design of Routing Tables for a Survivable Military Communications Network using Genetic Algorithms

Moore, S.J. & Sinclair, M.C.
Proc. Congress on Evolutionary Computation (CEC'99), Washington DC, USA, July 1999, pp.1788-1795

One of the vital areas in the design and operation of a survivable military telecommunications network is the selection of its routing tables. In this paper, both a bit-string genetic algorithm (GA) and an iterative stochastic hill climber (ISHC) are applied to two problem scenarios: with and without existing routing tables. Experimental results are reported for one destination node in an 18-node model network. Comparisons are made both between the GA and ISHC approaches, and with the pre-existing routing table. Overall, both the GA and the ISHC provide substantial improvements over the existing routing table, for both problem scenarios. However, the ISHC consistently obtains better results than the GA, often at reduced computational cost.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Evolutionary Telecommunications: Past, Present and Future

Sinclair, M.C., Corne, D. & Smith, G.D.
Proc. GECCO'99 Workshop on Evolutionary Telecommunications: Past, Present and Future, Orlando, Florida, USA, July 1999, p.208

This GECCO'99 workshop on ``Evolutionary Telecommunications: Past, Present and Future" focuses on evolutionary computation for telecommunications applications, particularly those involving areas unique to telecommunications, such as network design. Its two main aims are to establish the current state of the art in the field, as well as to discuss useful directions for future research in this important area.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS. The workshop also has a homepage.

Evolutionary Telecommunications: A Summary

Sinclair, M.C.
Proc. GECCO'99 Workshop on Evolutionary Telecommunications: Past, Present and Future, Orlando, Florida, USA, July 1999, pp.209-212

This paper provides an early summary of aspects of a nearly-exhaustive survey of evolutionary telecommunications, i.e. the application of evolutionary computation to the telecommunications problem domain. To the best of the author's knowledge, there has been no prior publication of a thorough survey in this area. It is hoped that the full summary, when published, will correct this omission.

Both the paper and presentation are available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Evolving an Artificial Vision System: Initial Considerations

Sinclair, M.C. & Clark, A.F.
Proc. GECCO'99 Workshop on Evolution of Sensors in Nature, Hardware and Simulation, Orlando, Florida, USA, July 1999, pp.191-195

Current machine vision systems have many limitations and cannot match the elegant complexity of the human vision system, comprising both the eye and its associated neural processing. However, engineering artificial vision systems by simulating natural ones is impractical, as the latter are not fully understood. Instead, the authors propose using directed evolution of software agents in an artificial environment thereby following a simplified natural evolutionary pathway leading to the creation of an artificial vision system.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Optical Mesh Topology Design using Node-Pair Encoding Genetic Programming

Sinclair, M.C.
Proc. Genetic and Evolutionary Computation Conference (GECCO-99), Orlando, Florida, USA, July 1999, pp.1192-1197

Two variants of a new node-pair encoding genetic programming (GP) approach for optical mesh network topology design are presented. In addition, a new variant of the earlier connected-nodes encoding is described. Experimental work on 15- and 20-node networks demonstrates that both GP approaches can almost match the design quality of bit-string genetic algorithms, particularly for the larger network size investigated.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Evolving Personal Agent Environments to Reduce Internet Information Overload: Initial Considerations

Pagonis, J. & Sinclair, M.C.
Proc. IEE Colloquium on Lost in the Web: Navigation on the Internet, Digest No. 1999/169, London, UK, November 1999, pp.2/1-2/10

As a means of dealing with the problem of information overload, particularly in the domain of the WWW, this paper outlines a proposal for a personal and adaptive agent-based system. Central to the design of the suggested system are the use of evolutionary algorithms, agent technologies, collaborative filtering, privacy, agent-society trust relationships, location awareness and mobility, as well as continual adaptation. As a major target, the proposed system aims to constantly and continuously evolve and adapt to the locational and behavioral changes of the user. Such a system will not be so much an advanced search engine, but rather a personal agent environment, which aims to transparently assist in the filtering and presentation of information. This will be based on observation of the user's individual behaviour, enhanced through adaptation and mobility. The goal is to design, and subsequently implement, a mobile personal system that eases the information overload problem and closely follows the individual user's interests. Only a truly personal system will be in position to cope with such demanding tasks.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

It has also been included in the IEE Computer Forum Library.

Impact of Topology on Wavelength and Switch-port Requirements in All-optical Hierarchical Multi-ring Networks

Proestaki, A. & Sinclair, M.C.
Proc. IEEE Global Telecom. Conf. (GLOBECOM'99), Rio de Janeiro, Brazil, December, 1999, pp.1035-1041

This paper focuses on dimensioning resilient, hierarchical, dual-homing, multi-ring architectures with or without wavelength converters. A novel dimensioning approach is presented to distribute traffic load between individual rings with the use of appropriate cutset-based analytical lower bounds. Evaluation of the proposed methods is facilitated by equivalent integer linear programming formulations tailored to multi-ring networks. Results obtained for structures adopting different interconnection schemes reveal that topology is a critical factor for both wavelength and hardware requirements.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


1998

Minimum Network Wavelength Requirement Design Using a Genetic-algorithm/Heuristic Hybrid

Sinclair, M.C.
Electronics Letters v34 n4 February 1998 pp.388-389

Minimum network wavelength requirement design of multi-wavelength all-optical transport networks using a genetic-algorithm(GA)/heuristic hybrid approach is described. Improved performance (over a GA alone) and improved results (over recent heuristics) are obtained using a tool for optical network optimisation, modelling and design (NOMaD).

Minimum Cost Routing and Wavelength Allocation Using a Genetic-algorithm/Heuristic Hybrid Approach

Sinclair, M.C.
Proc. Sixth IEE Conf. on Telecommunications, Edinburgh, UK, March/April 1998, pp.67-71

This paper describes early results in minimum cost routing and wavelength allocation of multi-wavelength all-optical transport networks using a genetic-algorithm (GA)/heuristic hybrid approach. The results were obtained using a tool for optical network optimisation, modelling and design (NOMaD) developed by the author.

This paper is available in HTML and gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Operator-probability Adaptation in a Genetic-algorithm/Heuristic Hybrid for Optical Network Wavelength Allocation

Sinclair, M.C.
Proc. IEEE Intl. Conf. on Evolutionary Computation (ICEC'98), Anchorage, Alaska, USA, May 1998, pp.840-845

Operator-probability adaptation in a genetic-algorithm/heuristic hybrid for minimum cost routing and wavelength allocation of multi-wavelength all-optical transport networks is described. The hybrid algorithm uses an object-oriented representation of networks, and incorporates four operators: path mutation, single-point crossover, reroute and shift-out. The adaptation algorithm is based on that by Davis, but uses simplified operator accounting. Experimental results from three fifteen-node test networks, obtained using a tool for optical network optimisation, modelling and design (NOMaD), illustrate the interesting dynamic behaviour of the adaptation algorithm. They suggest that, in this application, with powerful problem-specific operators, the main benefits of operator-probability adaptation are in relieving the experimenter of the burden of setting initial probabilities and in the early performance of the hybrid, rather than in improvements of the final solution quality obtained.

This paper is available in HTML and gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

NOMaD: An Optical Network Optimisation, Modelling and Design Toolset

Sinclair, M.C.
Proc. IEE Colloquium on Multiwavelength Optical Networks: Devices, Systems and Network Implementations, Digest No. 1998/296, London, UK, June 1998, pp.6/1-6/6

In recent years there has been a growing interest in the potential of multiwavelength all-optical transport networks to provide the huge bandwidth necessary if broadband services are widely adopted. As part of this effort, this paper provides an overview of a toolset for optical network optimisation, modelling and design (NOMaD). The toolset is used as part of the author's research into the application of genetic-algorithm (GA)/heuristic hybrid optimisation techniques to optical network design, as well as in several research projects. These include two under the European Commission funded research programme in Advanced Communications Technologies and Services (ACTS): WOTAN (Wavelength-agile Optical Transport and Access Network) and OPEN (Optical Pan-European Network); and the Fujitsu Telecommunications Europe Ltd. ``Future Broadband Networks'' project. Recent results using GA/heuristic hybrids for the design of multi-wavelength all-optical transport networks are described, including both topology, and routing, fibre and wavelength allocation.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


1997

Discovering Simple Fault-tolerant Routing Rules using Genetic Programming

Kirkwood, I.M.A., Shami, S.H. & Sinclair, M.C.
Proc. Intl. Conf. on Artificial Neural Networks and Genetic Algorithms (ICANNGA'97), Norwich, UK, April 1997, pp.285-288

A novel approach to solving network routing and restoration problems using the genetic programming (GP) paradigm is presented, in which a single robust and fault-tolerant program is evolved which determines the near-shortest paths through a network subject to link failures. The approach is then applied to five different test networks. In addition, two multi-population GP techniques are tried and the results compared to simple GP.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

NOMaD: Applying a Genetic-algorithm/Heuristic Hybrid Approach to Optical Network Topology Design

Sinclair, M.C.
Proc. Intl. Conf. on Artificial Neural Networks and Genetic Algorithms (ICANNGA'97), Norwich, UK, April 1997, pp.299-303

This paper describes the use of a genetic-algorithm (GA)/heuristic hybrid approach in a tool for optical network modelling, optimisation and design (NOMaD) being developed by the author at the University of Essex and, in particular, early results from its application to virtual-topology design.

This paper is available in HTML and gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

SS7 Network Management using Link Monitors

Jackson, E., Spindley, R., Sinclair, M.C. & Reader, S.
Proc. IEEE Intl. Conf. Commun. (ICC'97), Montreal, Canada, June 1997, pp.883-888

The disruption and loss of SS7 signalling networks during the summer of 1991 in North America by the "brown outs" and the resultant loss of services, revenue and customers, has focused the minds of many Telcos to put management systems in place to ensure network robustness. Their primary purpose being to identify problem trends earlier and speed up restoration of failed signalling components. We consider the role of SS7 link monitors in the management of a Common Channel Signalling (CCS) network. Several applications were prototyped as a proof of principle, demonstrating the suitability of the Inet GeoProbe System as a platform for service and network management applications.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Design of Fault-tolerant ATM Switch Based on Parallel Architecture

Segkhoonthod, S. & Sinclair, M.C.
Electronics Letters v33 n15 July 1997 pp.1289-1290

A fault-tolerant ATM switch comprising a distribution network and several routing networks in parallel is proposed. As the distribution network carries out part of the routing process, the routing networks are truncated, giving a low overall complexity. A performance evaluation of the switch is presented. The switch outperforms replicated networks but requires lower complexity.

Finite-source Analysis of Traffic on Private Mobile Radio Systems

Stevens, R.D. & Sinclair, M.C.
Electronics Letters v33 n15 July 1997 pp.1292-1293

Users of private mobile radio trunking systems often communicate in groups, queueing for a free channel if all channels are engaged. A finite-source queueing model is more appropriate than the infinite-source Erlang-C model. Performance equations, including the probability of delay exceeding a certain period, are derived.

Evolving Simple Fault-tolerant Routing Rules using Genetic Programming

Shami, S.H., Kirkwood, I.M.A., & Sinclair, M.C.
Electronics Letters v33 n17 August 1997 pp.1440-1441

A novel approach to solving network routing and restoration problems using the genetic programming (GP) paradigm is presented, in which a single robust and fault-tolerant program is evolved which determines the near-shortest paths through a network subject to link failures.

Genetic Programming Approaches for Minimum Cost Topology Optimisation of Optical Telecommunication Networks

Aiyarak, P., Saket, A.S. & Sinclair, M.C.
Proc. IEE/IEEE Intl. Conf. on Genetic Algorithms in Engineering Systems: Innovations and Applications (GALESIA'97), Glasgow, September 1997, pp.415-420

This paper compares the relative efficiency of three approaches for the minimum-cost topology optimisation of the COST 239 European Optical Network (EON) using genetic programming. The GP was run for the central nine nodes using three approaches: relational function set, decision trees, and connected nodes. Only the best two, decision trees and connected nodes, were run for the full EON. The results are also compared with earlier genetic algorithm work on the EON.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Evolving Simple Software Agents: Comparing Genetic Algorithm and Genetic Programming Performance

Sinclair, M.C. & Shami, S.H.
Proc. IEE/IEEE Intl. Conf. on Genetic Algorithms in Engineering Systems: Innovations and Applications (GALESIA'97), Glasgow, September 1997, pp.421-426

This paper investigates the relative efficiency of genetic algorithms and genetic programming in evolving simple software agents. The problem domain consists of an autonomous food-gathering agent placed on a square grid of hundred cells with food units spread evenly over the grid. Initial results show that evolving the agent using GP requires less effort than with GA. Nevertheless, further investigation revealed some interesting aspects.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


1996

Initial Survey of Heuristics for Optical Core Network Design in ACTS WOTAN

Proestaki, A. & Sinclair, M.C.
Proc. 13th UK Teletraffic Symposium, Glasgow, Mar 1996, pp.20/1-20/8

The principle aim of this paper is to describe the involvement of the University of Essex in the Network Design and Management Strategies workpackage of the Advanced Communications Technologies and Services (ACTS) Wavelength-agile Optical Transport and Access Network (WOTAN) project.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Heuristic Topological Design of Low-cost Optical Telecommunication Networks

Griffith, P.S., Proestaki, A. & Sinclair, M.C.
Proc. 12th UK Performance Engineering Workshop, Edinburgh, September 1996, pp.129-140

The aims of this paper are to describe five simple heuristics for low-cost virtual-topology design of flat (i.e. non-hierarchical) optical telecommunication networks, and then to assess their performance by applying them to ten test networks in a variety of sequences. (Virtual-topology design ignores the underlying physical reality of which ducts and fibres will actually be used.) The rules were chosen because of their inherent simplicity in deciding which node pairs to directly connect in a network, their potential for inclusion in subsequent genetic-algorithm/heuristic hybrid algorithms, and because it was hoped that they would form a useful foundation for more advanced traffic-sensitive design heuristics. Possible avenues for enhancing the original heuristics are also discussed.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Hierarchical Network Design for ACTS OPEN: Initial Considerations

Parnis, N., Jones, E.V., Sinclair, M.C. & O'Mahony, M.J.
Proc. 12th UK Performance Engineering Workshop, Edinburgh, September 1996, pp.141-155

This paper describes the work currently being undertaken by the University of Essex as part of the ACTS OPEN project. ACTS (Advanced Communications Technologies and Services) is the European Commission's major programme for supporting pre-competitive research and technological development in telecommunications and associated services.

The paper is logically divided into two major sections. The first introduces the OPEN (Optical Pan-European Network) project and defines its requirements, while the second deals with network performance parameters and objectives. The paper starts by giving a background for Project OPEN and then explaining the OPEN concept and principles behind transport networks. It then proceeds to highlight the major performance and behavioural characteristics required from such a network. The three architecture classes being considered in OPEN are outlined. A section on hierarchical networks, including a short literature survey on the subject concludes the first portion of the paper.

Next, performance parameters and objectives are discussed. The paper then describes the performance parameters identified so far in OPEN. It briefly introduces the network modelling tool being developed at the University of Essex, and concludes with some comments on future plans.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

NOMaD: Initial Architecture of an Optical Network Optimisation, Modelling and Design Tool

Sinclair, M.C.
Proc. 12th UK Performance Engineering Workshop, Edinburgh, September 1996, pp.157-167

This paper describes the initial architecture of a tool for optical network modelling, optimisation and design (NOMaD) being developed by the author at the University of Essex. NOMaD will be used as part of the author's own research into the application of genetic-algorithm/heuristic hybrid optimisation techniques to network design, as well as in several research projects, including two Advanced Communications Technologies and Services (ACTS) projects: WOTAN (Wavelength-agile Optical Transport and Access Network) and OPEN (Optical Pan-European Network). It is envisaged that the overall NOMaD architecture developed by the author will be extended by others to meet the requirements of their individual projects.

This paper is available in HTML and gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


1995

Analysis of a Fault-Tolerant ATM Switch Based on a Parallel Architecture

Segkhoonthod, S. & Sinclair, M.C.
Proc. 12th UK Teletraffic Symposium, Old Windsor, March 1995, pp.22/1-22/9

This paper presents a fault-tolerant ATM switch which adapts the idea of using MINs in parallel. It has a distribution network to distribute incoming packets to several routing networks arranged in parallel. Consequently, the IPC is simply required to submit packets to the distribution network. As the latter is designed to perform some of the routing itself, the routing networks are not required to carry out the whole routing process; consequently incomplete (i.e. truncated) routing networks are used. As a result, the overall complexity of the switch is not further increased by the introduction of the distribution network. The distribution network is also in charge of re-routing packets in the presence of a fault. Unlike other fault-tolerant networks where the routing algorithm is usually modified in order to avoid faults, in the proposed switch there is no modification to the routing algorithm in fault conditions: hence the re-routing process is simple and the complexity of switching elements is kept low. Further, it will be shown that the proposed switch gives both improved performance and lower complexity than replicated MINs.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Minimum Cost Topology Optimisation of the COST 239 European Optical Network

Sinclair, M.C.
Proc. Intl. Conf. on Artificial Neural Networks and Genetic Algorithms, Ales, France, April 1995, pp.26-29

A genetic algorithm is presented for the minimum-cost topology optimisation of the COST 239 European Optical Network (EON). The algorithm makes use of real traffic data where possible, and produces a network amongst twenty given nodes with two-shortest-node-disjoint routing between node pairs. Both routes are fully resourced, guaranteeing the network will survive a single component failure. The results are compared with the earlier `hand-crafted' EON topology.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Re-routing Analysis of a Fault-Tolerant ATM Switch Based on a Parallel Architecture

Segkhoonthod, S. & Sinclair, M.C.
Proc. 3rd Workshop on Performance Modelling and Evaluation of ATM Networks, Ilkley, July 1995, pp.73/1-73/12

In an earlier paper, we proposed a fault-tolerant ATM switch which adapts the idea of using several routing networks in parallel. In addition, we presented a probabilistic analysis of the proposed switch with re-routing deactivated, as well as simulation results for re-routing in the absence of faults. It was shown that the proposed switch gives both improved performance and reduced complexity when compared with replicated networks.

In this paper, we present a performance analysis of the switch with re-routing in the absence of faults, based on the method of state diagrams, and compare the results with simulation. As before, these show that the proposed switch gives improved performance when compared with replicated networks.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

A Comparative Study of k-Shortest Path Algorithms

Brander, A.W. & Sinclair, M.C.
Proc. 11th UK Performance Engineering Workshop, Liverpool, September 1995, pp.370-379

Efficient management of networks requires that the shortest route from one point (node) to another is known; this is termed the shortest path. It is often necessary to be able to determine alternative routes through the network, in case any part of the shortest path is damaged or busy. The k-shortest paths represent an ordered list of the alternative routes available. Four algorithms were selected for more detailed study from over seventy papers written on this subject since the 1950s. These four were implemented in the `C' programming language and, on the basis of the results, an assessment was made of their relative performance.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Wavelength Assignment between the Central Nodes of the COST 239 European Optical Network

Tan, L.G. & Sinclair, M.C.
Proc. 11th UK Performance Engineering Workshop, Liverpool, September 1995, pp.235-247

Finding an optimised route and wavelength allocation plan is an NP-complete problem in WDM networks. A genetic algorithm to optimise the allocation plan on the eleven central nodes of COST 239 European Optical Network is presented. Use was made of real traffic data where possible, and several route and wavelength allocation plans were produced for the network. Both Wavelength Path and Virtual Wavelength Path routing schemes were considered in the route and wavelength assignment process.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Performance Analysis of a Fault-tolerant ATM Switch in Single-fault Conditions

Segkhoonthod, S. & Sinclair, M.C.
Proc. 11th UK Performance Engineering Workshop, Liverpool, September 1995, pp.48-63

In two earlier papers, we proposed a fault-tolerant ATM switch which adapts the idea of using several routing networks in parallel. In the first, we presented a probabilistic analysis of the proposed switch with re-routing deactivated, as well as simulation results for re-routing in the absence of faults. It was shown that the proposed switch gives both improved performance and reduced complexity when compared with replicated networks. In the second, we presented a performance analysis of the switch with re-routing in the absence of faults, based on the method of state diagrams, and compared the results with simulation. The results obtained showed reasonable agreement between the analysis and simulation. Further, the performance of the proposed switch with re-routing is significantly better than without. In this paper, we extend the work in the second paper by taking into account the presence of a single fault in various parts of the switch.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


1994

Improved Model for European International Telephony Traffic

Sinclair, M.C.
Electronics Letters v30 n18 September 1994 pp.1468-1470

A new model (termed the PFD model) for European international telephony traffic is given that improves on the author's earlier PD model. The PFD model introduces penetration factors to provide a far better match to actual traffic data than the use of population and distance alone.


1993

The Application of a Genetic Algorithm to Trunk Network Routing Table Optimisation

Sinclair, M.C.
Proc. 10th UK Teletraffic Symposium, Martlesham Heath, April 1993, pp.2/1-2/6

In a 1991 paper, this author gave a method for the overall NGOS, by single-moment analysis, of fixed-alternative-routing (FAR) circuit-switched communications networks with reliable nodes but unreliable links. The method employs a Markov model for an unreliable link, in combination with earlier work, so as to greatly reduce execution time compared to prior algorithms.

In two subsequent papers, this author used the analysis method as part of three heuristic routing table optimisation algorithms, which obtain routing tables such that the overall NGOS is minimised under different call control rules. These algorithms were then used to demonstrate the improvements in trunk network fault-tolerance (assessed in terms of the overall NGOS) that can be achieved both through routing table updating in the event of link failure], and through network augmentation i.e. the addition of extra links to a network, either in parallel with existing links, or between nodes that previously had no direct connection.

In the current paper, an alternative approach to routing table optimisation is taken, based on combining a genetic algorithm with Sinclair's analysis method. The paper begins by describing the network model used and, briefly, both the underlying analysis method and the earlier heuristic optimisation methods. The basic principles of genetic algorithms are presented, and the details of the particular genetic algorithm used here are described. The paper concludes with a comparison of the execution times and results obtained for an example network with those from Sinclair's heuristic method, and some suggestions for possible future work.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Ultra-High Capacity Optical Transmission Network: European Research Project COST 239

O'Mahony, M., Sinclair, M.C. & Mikac, B.
Information, Telecommunications, Automata Journal v12 n1-3 1993 pp.33-45

In this paper the basic facts, framework and objectives of European research project COST 239 are given. Network aspects of the Project are discussed in detail. The initial topology of European Optical Network and the initial traffic data - based on population/distance method - are introduced. The calculation of grade-of-service is carried out. A software tool for solving graph-oriented telecommunication problems and its application in reliability evaluation are presented.


1992

Trunk Network Fault-Tolerance through Routing Table Updating in the Event of Trunk Failure

Sinclair, M.C.
Proc. 9th UK Teletraffic Symposium, Guildford, April 1992, pp.17/1-17/9

In a recent paper, two methods were given for the single-moment analysis of fixed-alternative-routing circuit-switched communications networks with reliable nodes but unreliable links. The second of these, MKV_GOS, employs a Markov model for an unreliable link, in combination with earlier work, so as to greatly reduce execution time compared to existing algorithms.

In the current paper, the MKV_GOS method is used as part of three heuristic routing table optimisation algorithms, which obtain routing tables such that the overall network grade-of-service is minimised under different call control rules. These algorithms are then used to demonstrate the improvements in trunk network fault-tolerance (assessed in terms of the network grade-of-service) that can be achieved through routing table updating in the event of link (trunk group) failure.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Trunk Network Fault-Tolerance through Network Augmentation

Sinclair, M.C.
Proc. 4th Bangor Symposium on Communications, University of Wales - Bangor, May 1992, pp.252-256

In a recent paper, two methods were given for the single-moment analysis of fixed-alternative-routing (FAR) circuit-switched communications networks with reliable nodes but unreliable links. The second of these, MKV_GOS, employs a Markov model for an unreliable link, in combination with earlier work, so as to greatly reduce execution time compared to existing algorithms.

In a second paper, the MKV_GOS method was used as part of three heuristic routing table optimisation algorithms, which obtain routing tables such that the overall NGOS is minimised under different call control rules. These algorithms were then used to demonstrate the improvements in trunk network fault-tolerance that can be achieved through routing table updating in the event of link failure.

In the current paper, a brief review is given of the MKV_GOS method and its application in the three heuristic routing table optimisation algorithms. The three algorithms are then used to demonstrate the improvements in trunk network fault-tolerance (assessed in terms of the overall NGOS) that can be achieved through network augmentation i.e. the addition of extra links to a network, either in parallel with existing links, or between nodes that previously had no direct connection.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.

Single-Moment Analysis of Unreliable Trunk Networks Employing K-Shortest-Path Routing

Sinclair, M.C.
Proc. IEE Colloquium on Resilience in Optical Networks, Digest No. 1992/189, London, UK, October 1992, pp.3/1-3/6

In a recent paper, two methods were given for the single-moment analysis of fixed-alternative-routing (FAR) circuit-switched communications networks with reliable nodes but unreliable links. The second of these, MKV_GOS, employs a Markov model for an unreliable link, in combination with earlier work, so as to greatly reduce execution time compared to existing algorithms.

In the current paper, an extension to the MKV_GOS method, which was originally limited to OOC-SF (Originating Office Control with Spill-Forward) table-based routing, is described. This extension allows the analysis of networks employing two additional types of routing, K-shortest-disjoint-loopless-path and K-shortest-loopless-path. The extended method is then demonstrated by comparing results for the two K-shortest-path routing types in terms of their overall NGOS for an example network. In addition, the execution time of the method for a series of networks of increasing size is presented.

This paper is available in gzip-ed PostScript. Also, if you need it, download gzip for Unix (tar file) or MSDOS.


Please feel free to comment on this page.
Creator: Mark C Sinclair <mcs@ieee.org>
Date: 5 ix 2001

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