Research Papers - Department of Electrical and Electronic Engineering

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Start date: 2000End date: 2009

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    Free route air traffic flow manager
    (IEEE, 2005-12-11) Abeysooriya, M; Kulasekere, E. C
    As the world moves towards the era of globalization and as the business world continues to revolutionize, meeting the expectations of a timely and safe air transportation system has become major challenge to the field of aviation. Most of the existing air traffic control systems primarily focus on generating pre-defined routes for aircrafts based on the 'fixed route model'. But with the advancement of technologies in the field of aviation an effective and practical mechanism called 'free route modeling' has been introduced. The few test beds that exist worldwide based on this concept, have been implemented for certain specific airspaces eliminating the possibility of using this strategy at any location worldwide. This paper presents the design and implementation of the 'free route air traffic flow manager' project which proposes a framework which can be used as a generic tool to over come this limitation. This tool will allow the user to dynamically create a free route modeling system for a certain airspace by configuring a 3D airspace according to the given requirements for that airspace. The dynamically developed free route modeling system will facilitate the functionalities of generating the initial free route for an aircraft & provide dynamic re- planning for the configured air space when a conflicting scenario is reported.
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    Distributed Wireless CSMA/CA based Unified Navigation Solution
    (IEEE, 2006-12-15) Samarakoon, S. M. D. D; Silva, A. P. M; Samaraweera, S. M. D. W; Fernando, T. G. A; Kulasekere, E. C
    This research proposes a multiple access protocol known as the Distributed Wireless CSMA/CA (DWCC). This protocol is optimized for a distributed wireless communication network where the node availability and behavior are both uncertain and unpredictable. An application based on a distributed communication network formed using inter vessels communication at deep sea is used to illustrate the salient features of the proposed protocol. A method is outlined on how the proposed new protocol can be applied to extend radar vision at each vessel in the presence of radar jamming and/or communication node failure at mid sea. That is, the DWCC protocol is used to gather information from all vessels to construct a cumulative radar map at any node and thus extending the radar vision beyond the display capability of a single node.
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    Role of the Context in Intuitive Combination of Evidence
    (IEEE, 2008-12-12) Senaratne, D; Kulasekere, E. C
    Combination' in `Theory of Evidence' is merging evidence received from different sources to reduce the uncertainty one entertains regarding the problem in concern. Rules having different semantics and producing conflicting outputs are found in literature. Unfortunately proper guidelines are not available to select the combination rules suitable for a given problem. It has resulted in counter-intuitive use of the rules. Contextual information governs how the frames against which the evidence is expressed are related. It is however not embedded in the evidence and therefore not available to the agent applying the combination rule. This paper explores how contextual information can be extracted to be used for improving the intuitiveness of combination. It establishes a systematic way to extract contextual information, based on what the authors denote as hypothesis-level and frame-level inter-frame relationships.
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    Enhancing flexibility of belief representations
    (IEEE, 2008-04-06) Senaratne, D; Kulasekere, E. C
    Several attempts have been made to enhance the flexibility of belief representation in the Shafer model. This paper questions their ability to retain the intuitiveness. A method of enhancing the flexibility of belief representations, without compromising the intuitiveness is proposed. In it we relax the Shafer's exclusivity constraint by disregarding the formalism: 'subsets as propositions' and expressing support as functions of propositions. A compact and intuitive notation for propositions, termed N-of, is introduced. This notation simplifies the formulation of propositions from the statements humans make.
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    An analytical framework for cluster distribution of EDCR class of algorithms in Wireless Sensor Networks
    (IEEE, 2009-12-28) Gamwarige, S; Kulasekere, E. C
    Energy Driven Cluster-Head Rotation (EDCR) class of algorithms are energy aware distributed clustering techniques for effective ad hoc deployed Wireless Sensor Network (WSN) organization. The application of this class of algorithms requires the setting of salient parameters at the design stage of the WSN to achieve desired results. Two such parameters which should be known in advance are the cluster density and the distance between neighbouring cluster heads (CHs). In this research we analyze the effect of algorithm design based on these two parameters. Simulation techniques are given to support and verify the analytical results.
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    Performance analysis of the edcr algorithm in a distributed wireless sensor network
    (IEEE, 2006-04-11) Gamwarige, S; Kulasekere, E. C
    The energy driven cluster-head rotation (EDCR) algorithm proposed in S. Gamwarige and E. Kulasekere (2005) has been shown to out performed existing clustering algorithms such as LEACH (W.B. Heinzelman et al., 2002), HEED (O. Younis and S. Fahmy, 2004), ANTCLUST based (J. Kamimura et al., 2004) and SEP (G. Smaragdakis et al., 2004) in terms of END and PNA (95%) lifetime metrics in a distributed wireless sensor network (WSN). In this paper we present theoretical analysis of the performance parameters such as the optimum transmission range (R opt ) and the clustering trigger threshold value (lambda i ) of EDCR in terms correctness and complexity of the algorithm. Further we explain how to find the optimal values for such parameters in order to maximize the network lifetime
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    A cluster based energy balancing strategy to improve Wireless Sensor Networks lifetime
    (IEEE, 2007-08-09) Gamwarige, S; Kulasekere, E. C
    Wireless Sensor Networks (WSNs) have been of interest due to its many areas of application. The lifetime of the sensor bed is of crucial importance for the successful deployment of such networks. Many algorithms have been proposed based on clustering and cluster head (CH) rotation to improve the lifetime of WSNs. EDCR [1] and EDCR-MH [2] are two such algorithms that have shown promising results. The lifetime of the entire sensor bed can be significantly improved if the energy associated with a sensor node is depleted at the same rate irrespective of its location with respect to the Base Station (BS). This research proposes a new algorithm for CH selection and rotation that incorporates the desirable features of both EDCR and EDCRMH together with a modified minimum distance communication between CH and BS. The algorithm is capable of balancing the energy depletion rate of sensor nodes across the entire sensor bed irrespective of their node locations. Unlike previous algorithms, the proposed algorithm can be applied to significantly larger sensor beds while maintaining the lifetime performance. Analytical models are presented to identify salient parameters of the proposed algorithm. Simulation results are provided to illustrate the applicability of the algorithm. The results indicate that the lifetime of the entire sensor bed is improved over existing algorithms.
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    Application of the edcr algorithm in a cluster based multi-hop wireless sensor network
    (IEEE, 2006-10-18) Gamwarige, S; Kulasekere, E. C
    The energy driven cluster head rotation algorithm proposed in (Gamwarige, S and Kulasekere, E, 2005) and analyzed in (Gamwarige, S and Kulasekere, E, 2006) is based on a single hop communication model where the data messages from each cluster head (CH) node is sent directly to the base station (BS). As a result when the wireless sensor network (WSN) dimensions are large, the nodes located far away from the BS die much faster. In this paper a method of extending the lifetime of the WSN based on a multihop communication model applied to the EDCR algorithm is proposed. The modified EDCR (EDCR-MH) relays all CH to BS messages via other CH nodes by computing a shortest path based on local heuristic information. Further, the EDCR-MH also has provisions to minimize the burden due to excessive data relay on nodes closer to the BS. The results indicate that the proposed algorithm out performs algorithms like under similar conditions
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    PublicationOpen Access
    An energy efficient distributed clustering algorithm for ad hoc deployed wireless sensor networks in building monitoring applications
    (2009-01-01) Gamwarige, S; Kulasekere, E. C
    In recent years Wireless Sensor Networks (WSNs) have been deployed for Building Monitoring (BM) as they provide a low cost and reconfigurable alternative to centralized cable based sensor systems. Using WSNs gives rise to unique issues in its practical usage. Lifetime of a WSN is one such crucial issue to be addressed during deployment. Clustering is an effective way of extending the lifetime of a WSN. In this article we propose a distributed and energy driven clustering algorithm where the selection of the cluster heads (CHs) are based on relative residual energy level of sensors. Furthermore, the CHs are rotated only when their energy drops below a dynamic threshold computed by the algorithm. As a result, the overheads in the inter sensor communications will be reduced and thereby the proposed algorithm will favor more powerful nodes over the weaker ones to prolong the lifetime of the entire WSN. This will effectively prolong the usability of the monitoring system and thus the underlying safety of the building. The results will show that the proposed algorithm performs better when compared to existing clustering algorithms. Further we present theoretical analysis of the performance of the proposed algorithm in terms of correctness and complexity and explain how to identify the optimal values for key parameters such as transmission range and re-clustering trigger threshold function value in order to maximize the network lifetime
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    Optimization of cluster head rotation in energy constrained wireless sensor networks
    (IEEE, 2007-07-02) Gamwarige, S; Kulasekere, E. C
    The performance of energy driven cluster head (CH) rotation algorithms have been shown to be far more superior to time driven CH rotation algorithms when it comes to maximizing the sensor bed lifetime. The sensor bed life time is improved by selecting the proper points at which a CH role is relinquished to higher energy nodes via a CH rotation phase. However no formal analytical method is available to find the optimal point at which the CH rotation should be carried out. This research proposes an analytical iterative method to obtain the optimal points at which the CH rotation can be carried out. The method proposes an optimal value c opt for the energy threshold at which this rotation could occur. The values obtained via the analytical method is shown to be optimal via simulations using the EDCR and EDCR-MH algorithms. The analytical method proposed can be used in any energy driven algorithm to find the optimal point for CH rotations avoiding any ad hoc simulation based methods to maximize the lifetime of the sensor bed.