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Communication Theory, Reliability, and Quality of Service, 2009. CTRQ '09. Second International Conference on

Date 20-25 July 2009

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Displaying Results 1 - 25 of 33
  • [Front cover]

    Publication Year: 2009 , Page(s): C1
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  • [Title page i]

    Publication Year: 2009 , Page(s): i
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  • [Title page iii]

    Publication Year: 2009 , Page(s): iii
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  • [Copyright notice]

    Publication Year: 2009 , Page(s): iv
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  • Table of contents

    Publication Year: 2009 , Page(s): v - vii
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  • Preface

    Publication Year: 2009 , Page(s): viii
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  • Organizing Committee

    Publication Year: 2009 , Page(s): ix - x
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  • list-reviewer

    Publication Year: 2009 , Page(s): xi - xii
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  • SRGMs Based on Stochastic Differential Equations

    Publication Year: 2009 , Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (914 KB) |  | HTML iconHTML  

    This paper presents a software reliability growth model based on Ito type stochastic differential equation. As the size of a software system is large, the number of faults detected during the testing phase becomes large ; the change of the number of faults, which are detected and removed through each debugging, becomes sufficiently small compared with the initial fault content at the beginning of the testing phase. In such a situation, we can model the software fault detection process as a stochastic process with continuous state space. In this paper, two new software reliability growth model based on Ito type of stochastic differential equation has been proposed. In software reliability growth model 1 stochastic differential equation based generalized Erlang model and in software reliability growth model 2 stochastic differential equation based generalized Erlang model with logistic error detection function is being considered. View full abstract»

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  • Test Purpose Generation for Timed Protocol Testing

    Publication Year: 2009 , Page(s): 8 - 14
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (838 KB) |  | HTML iconHTML  

    Test purposes are requirements, usually constructed by hand, which aim at testing critical properties on implementations. These ones are then used by testing methods to generate test cases. Writing them manually is a heavy task, this is why we propose several techniques to generate test purposes automatically or semi-automatically from a specification. These methods use different strategies for test purpose generation in order to focus on specific communication protocol properties like the test of critical states and actions, or the test of service invocations.These methods are basically based on a test purpose design language which takes into consideration testability. This one measures the test quality of a system with the evaluation of several criteria (observability, controllability,...). Measuring the testability while generating test purposes helps to reduce the test costs and helps to improve the fault detection during the testing process. View full abstract»

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  • Maximizing the Availability and Reliability of Videos in VoD System Using Markov Chain

    Publication Year: 2009 , Page(s): 15 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (947 KB) |  | HTML iconHTML  

    In a Video on Demand system, by forwarding the server video stream client by client, a chain based scheme is formed, which reduces the server load. The existing chaining schemes are not reliable because there are frequent breaks in the chain among the clients due to stringent bandwidth and buffer, stop fail, and hardware and software failures. This leads to stream failures within the client, in turn affects other clients in the cluster. Then, the performance of the overall system degrades. To achieve system reliability we formulated a continuous time Markov chain reliability model and analyzed the availability and reliability of the streams during the intricate circumstances. Numerical results show that for 5000 streams, we obtain the reliability between 60% and 80%, even though the individual clients are highly unreliable. View full abstract»

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  • Attacker Independent Stability Guarantees for Peer-2-Peer-Live-Streaming Topologies

    Publication Year: 2009 , Page(s): 20 - 25
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (745 KB) |  | HTML iconHTML  

    Live streaming systems based on application layer multicast (ALM) technology provide an effective and scalable way for content dissemination. Especially push-based systems, maintaining an explicit distribution topology, represent a promising approach. Compared to a classical client-server content distribution and in contrast to other ALM systems, they introduce only low additional transport delay and jitter. However, these systems are vulnerable towards random node failures or intended attacks. In this article, we select packet loss as a natural damage measure and show that there exists an attacker- independent concept of optimal stability of streaming topologies in push approaches. We are able to identify such optimally stable topologies by minimizing an upper bound on the sequence of damages any attacker may achieve on a topology. Furthermore, we show an easily constructible subclass of these topologies and present the unexpected result that deciding membership in the complete class of optimally stable topologies is a co-NP-complete problem. View full abstract»

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  • Priority Transmission of SIP Signaling Flows in Case of IP Link Congestion

    Publication Year: 2009 , Page(s): 26 - 31
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (947 KB) |  | HTML iconHTML  

    Conceptual framework of next generation network (NGN) is based on Internet protocol (IP) transport technology, which is generally accepted as the optimal solution for delivering of next generation multimedia services. Although packet-switched networks are in the mainstream, decades of experience with circuit-switched networks still set expectations when it comes to quality of service (QoS). As opposed to circuit-switched networks, signaling flow and media flow of NGN services are mixed in transmission. That makes it difficult for an IP network node to guarantee the signaling flow packet is not discarded in case of the congestion, which results in an impossibility to trigger the framework of dynamic QoS negotiation and implement service reachability. Since the service reachability is guaranteed in the signaling flow transmission aspect, it is necessary to consider the possibility of IP network to fulfill expectations regarding the straightway and reliable transmission of signaling flows. In this paper, the link congestion effect on critical performance metrics of session initiation protocol (SIP) signaling flows is investigated by performing extensive simulation study. Our results indicate that IP network is able to guarantee transmission criteria of SIP signaling flows even in case of critical link congestion when the highest priority is assigned to them. View full abstract»

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  • LAR Image Transmission over Fading Channels: A Hierarchical Protection Solution

    Publication Year: 2009 , Page(s): 32 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1736 KB) |  | HTML iconHTML  

    The aim of this paper is to present an efficient scheme to transmit a compressed digital image over a non frequency selective Rayleigh fading channel. The proposed scheme is based on the locally adaptive resolution (LAR) algorithm, and the Reed-Solomon error correcting code is used to protect the data against the channel errors. In order to optimize the protection rate and ensure better protection we introduce an unequal error protection (UEP) strategy, where we take the hierarchy of the information into account. The digital communication system also includes appropriate interleaving and differential modulation. Simulation results clearly show that our scheme presents an efficient solution for image transmission over wireless channels, and provides a high quality of service, outperforming the JPWL scheme in high bit error rate conditions. View full abstract»

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  • Measurement-Based Connection Admission Control Methods for Real-Time Services in IEEE 802.16e

    Publication Year: 2009 , Page(s): 37 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (826 KB) |  | HTML iconHTML  

    In this paper, we present two simple-to-implement measurement-based admission control methods for real-time services in IEEE 802.16e networks. The first method simply utilizes the averaged number of free slots as input in admission decisions while the second method is more advanced and it tunes the admission thresholds according to current traffic load. Our simulations show that the proposed methods lead into more efficient use of scarce radio resources-without sacrificing the quality of service (QoS) requirements - than using parameter-based, i.e., static, connection admission control. View full abstract»

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  • A Clustering-Based Scalable Key Management Protocol for Ad Hoc Networks

    Publication Year: 2009 , Page(s): 42 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB) |  | HTML iconHTML  

    In this paper, we address a scalable key management protocol for ad hoc networks, this protocol is based on new clustering technique. The network is partitioned into communities or clusters based on affinity relationships between nodes. To ensure trusted communications between nodes we proposed two types of keys generated by each clusterhead. The protocol is adaptive according to the limitation of the mobile nodespsila battery power and to the dynamic network topology changes. View full abstract»

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  • Minimum Timing Jitter in Timing Recovery Based on Pre-filtered Square-Law Timing Detection

    Publication Year: 2009 , Page(s): 46 - 51
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (836 KB) |  | HTML iconHTML  

    New results about the pre-filter and the post-filter in timing recovery based on square-law detection are presented. Specifically, in the paper a matched-filter-type condition that guarantees optimality of the pre-filter against channel noise is derived. This condition can be satisfied together with the known condition for self-noise elimination, thus achieving optimality against self-noise and against channel noise simultaneously. The post-filter is optimized by introducing a phase noise model for the phase of the timing wave used at the transmit side for generating the data signal. The case of random phase walk is analyzed in detail, and, having optimized both the pre-filter and the post-filter, we conclude that the minimum variance of the normalized timing error for a given spectral quality of the source timing wave and for a given channel signal-to-noise ratio goes with (alphaT)-0.5, where T is the symbol repetition interval and alpha is the roll-off factor. View full abstract»

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  • Active Worm Propagation in Hierarchical Peer-to-Peer Network Management Systems

    Publication Year: 2009 , Page(s): 52 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (830 KB) |  | HTML iconHTML  

    Currently there is a growing belief that using peer-to-peer (P2P) approach leads to noticeable improvement in the performance of network management systems (NMSs). However P2P systems can be potential vehicle for active worms which can spread in all manager peers in a short time. This issue has not been studied in the literature. In this paper we address effects of active worm propagation in a P2P network management system in which nodes are structured in several hierarchal levels. We intend to evaluate the speed of propagation in the system. To aim at this goal, we perform extensive simulation study and investigate the parameters influencing the speed of propagation such as the number of vulnerable host managers, degree of connections between peer managers inside the groups, the number of connections between different groups of managers in the hierarchical structure. We further compare worm propagation in different levels of hierarchy by different types of active worm attack strategies. We show that in addition to P2P parameters hierarchical structure affect the speed of active worm propagation. This issue suggests that P2P network management systems are more vulnerable in comparison to classical NMSs when they face to security attacks. Therefore to realize implementation of P2P NMSs security concerns should be taken into account. View full abstract»

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  • A Novel Method for Task Scheduling in Distributed Systems Using Memetic

    Publication Year: 2009 , Page(s): 58 - 62
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB) |  | HTML iconHTML  

    Tasks scheduling problem is a key factor for a distributed system in order to achieve better efficiency. The problem of tasks scheduling in a distributed system can be stated as allocating tasks to the processor of each computer. The objective of this problem is minimizing makespan and communication cost, while maximizing CPU utilization. Scheduling problem is known as being NP-complete. Hence, many genetic algorithms have been proposed to search optimal solutions from entire solution space. However, these existing approaches are going to scan the entire solution space without consideration to techniques that can reduce the complexity of the optimization. In other words, the main shortcoming of these approaches is to spend much time doing scheduling, and hence, needing exhaustive time. Therefore, in this paper we use memetic algorithm to cope with this shortcoming. We apply Tabu search as local search in our proposed memetic algorithm. Extended simulation results demonstrate that the proposed method outperforms the existent GA-based method in terms of communication cost, CPU utilization and makespan. View full abstract»

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  • Self Fault-Managed and High Available P2P Architecture for Next Generation Network Management Systems

    Publication Year: 2009 , Page(s): 63 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (921 KB) |  | HTML iconHTML  

    In this paper, we propose a self fault-managed and self reconfigurable peer-to-peer architecture for increasing the availability of the network management system (NMS). We intend to achieve such a goal through increasing fault tolerance property of the NMS by applying redundancy. However the architecture we proposed does not impose any hardware redundancy but software redundancy. This is mainly because we use some peers in several roles and thus add some software redundancy which is easily tolerable by advance processors of NMSpsilas peers. We conduct extensive simulation study to examine the performance of the proposed architecture in presence of nodes' failure. We also investigate effect of failure in different nodes and sensitiveness of the architecture to those failures. The results show that the proposed architecture offers higher availability in comparison to a non-fault tolerant Peer-to-Peer NMS. View full abstract»

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  • A New Approach for Election Algorithm in Distributed Systems

    Publication Year: 2009 , Page(s): 70 - 74
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB) |  | HTML iconHTML  

    Leader election is an important problem in distributed computing systems. In this problem, when the leader is crashed, other nodes must elect another leader. Garcia-Molinapsilas Bully Algorithm is a classic solution to cope with this problem. In this paper we introduce a new method based on electing a leader and alternatives. If the leader crash, the alternative takes, care of the leader's responsibilities. Our results revealed that often, after a leader crash, leader alternative elect as a leader and continue to work. increases. We show that our proposed algorithm is more efficient than the Garcia Molinapsilas one in term of time, message complexity and in the fewer stages. View full abstract»

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  • Evaluating the Impact of Storage Capacity Constraints on Vehicular Delay-Tolerant Networks

    Publication Year: 2009 , Page(s): 75 - 80
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2491 KB) |  | HTML iconHTML  

    Vehicular delay-tolerant network (VDTN) was proposed as a particular application of a mobile delay-tolerant network (DTN), where vehicles act as the communication infrastructure for the network, relaying messages between the network nodes. In this paper, we consider the use of a VDTN to provide low-cost asynchronous communication between sparse populations spread over a remote vast region. We analyze the influence of the VDTN network nodepsilas storage capacity (buffer size), on the efficiency of four DTN routing protocols, in terms of message delivery probability. Our scenarios show that the routing protocols message replication strategies react differently to the increase of buffer size in specific network nodes. Epidemic and MaxProp protocols benefit from the increase of the storage capacity on all network nodes. Spray and Wait protocol only takes advantage on the increase of the vehicle's buffer capacity. We expect that this paper will provide a deep understanding of the implications of storage constraints over the performance of a VDTN, leading to insights for future routing algorithm and buffer management theoretic studies and protocol design. View full abstract»

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  • A Variable Neighborhood Search Heuristic for Point Coverage, Sink Location and Data Routing in Wireless Sensor Networks

    Publication Year: 2009 , Page(s): 81 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (433 KB) |  | HTML iconHTML  

    In this work point coverage, sink location and data routing problems are considered in an integrated way and two new mixed integer programming formulations are proposed. Since these models are computationally difficult to solve, a hierarchical solution procedure is proposed. In the top level, best sensor locations are sought by variable neighbourhood search. Given the sensor locations, a simpler formulation can be obtained and a Lagrangean heuristic is used to solve the sink location and data routing model efficiently. Experimental results indicate that the performance of hierarchical solution approach is very good. View full abstract»

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  • A Distributed Fuzzy-Based Failure Management for Wireless Sensor Networks

    Publication Year: 2009 , Page(s): 87 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (894 KB) |  | HTML iconHTML  

    In addition to limited energy resources in wireless sensor networks, failure of the nodes is a constraint to provide a reliable communication. As the failure of a node may have many reasons like mobility of the node and node or link failure, it is clear that in a real environment, we cannot control or reduce the number of failure in a network but itpsilas possible to manage it. In this paper, we propose a technique to improve routing protocols by considering both energy and failure constraints and managing them. By using this technique, the routing protocols dynamically adapt to nodespsila failure. The simulations results show the efficiency of this technique in two sample routing protocols. View full abstract»

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  • On the Optimal Tree-Based Explicit Multicast Routing

    Publication Year: 2009 , Page(s): 91 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB) |  | HTML iconHTML  

    This paper aims to introduce the hard optimization problem of determining tree-based explicit multicast routes with minimum cost. Explicit multicast routing has been proposed as a technique to solve the problem of multicast scalability in IP-based networks. Tree-based explicit routing is a special routing technique in which the multicast tree is encoded explicitly in the datagram headers. These enlarged headers may result in significant overhead traffic, so the cost minimization of this kind of routing is a relevant topic.This paper formulates the optimization of the communication cost per bit in tree-based explicit multicasting.If the multicast group is large, several trees are needed to provide routing for the entire group.It is demonstrated that the computation of the set of trees with minimum cost is an NP-difficult problem.The aim of the paper is the introduction of the hard optimization problem to find tree-based explicit multicast routes with minimum cost. The presented theoretical analysis is indispensable to find cost efficient routes for these kinds of multicast routing protocol. View full abstract»

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