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Communication Theory, Reliability, and Quality of Service, 2008. CTRQ '08. International Conference on

Date June 29 2008-July 5 2008

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  • [Front cover]

    Page(s): C1
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  • [Title page i]

    Page(s): i
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  • [Title page iii]

    Page(s): iii
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  • [Copyright notice]

    Page(s): iv
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  • Table of contents

    Page(s): v - vi
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  • Preface

    Page(s): vii
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  • Committee

    Page(s): viii - ix
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  • Security and Spatial Resolution Optimization for Cluster-Based Wireless Sensor Networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (433 KB) |  | HTML iconHTML  

    In this study, we investigate the correlation between security and spatial resolution -a measure of service quality- in cluster-based wireless sensor networks (WSN). We analyze the tradeoff between these two concepts resulting from the limited channel capacity. We propose a method based on combinatorial optimization to determine the best tradeoff between security and spatial resolution for cases where network capacity is not sufficient to support required levels. The proposed method involves formulation of an optimization problem by utility maximizing approach and its solution by a heuristic algorithm providing minimal operational complexity. We also present some numerical results obtained by application of the proposed method to a sample sensor network. The numerical results demonstrate the effect of utility function parameters on the optimal solution. View full abstract»

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  • Cooperation Enforcement in Vehicular Networks

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB) |  | HTML iconHTML  

    Operations of vehicular ad hoc networks rely on the collaboration of participating nodes to route data for each other. This standard approach using a fixed set of nodes for each communication link cannot cope with high mobility due to a high frequency of link breaks. A recent approach based on virtual routers has been proposed to address this problem. In this new environment, virtual routers are used for forwarding data. The functionality of each virtual router is provided by the mobile devices currently within its spatial proximity. Since these routers do not move, the communication links are much more robust compared to those of the conventional techniques. In this paper, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Simulation results based on various system configurations are given. They indicate that the proposed technique is effective. View full abstract»

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  • An Improved Quorum Selection Algorithm

    Page(s): 13 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (437 KB) |  | HTML iconHTML  

    As communication becomes more and more an integral part of our day to day lives, so our need to access information increases as well. Mobility is currently one of the most important factors to consider in our aim to achieve ubiquitous computing, and with it raises the problem of how to manipulate data while maintaining consistency and integrity. Recent years have seen tremendous interest in quorum systems adapted to mobile hosts; however, the more recent topic, of studying the effects of mobile networks on quorum systems, has also been the focus of interest for building quorums aware of their network surroundings. This paper presents a novel approach in selecting mobile hosts to form epidemic quorum coteries, based on metrics measured by mobile hosts and then transmitted to base station servers, which maintain a vigil on the state of these mobile hosts to provide higher quorum availability and ultimately higher data accessibility, better integrity and consistency. View full abstract»

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  • Past, Present and Future of IP Telephony

    Page(s): 19 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB) |  | HTML iconHTML  

    Since the late 90's IP telephony, commonly referred to as Voice over IP (VoIP), has been presented as a revolution on communications enabling the possibility to converge historically separated voice and data networks, reducing costs, and integrating voice, data and video on applications. This paper presents a study over the standard VoIP protocols H.323, session initiation protocol (SIP), media gateway control protocol (MGCP), and H.248/Megaco. Given the fact that H.323 and SIP are more widespread than the others, we focus our study on them. For each of these protocols we describe and discuss its main capabilities, architecture, stack protocol, and characteristics. We also briefly point their technical limitations. Furthermore, we present the advanced multimedia system (AMS) project, a new system that aims to operate on Next Generation Networks (NGN) taking the advantage of its features, and it is viewed as the successor to H.323 and SIP. View full abstract»

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  • Analytical Model for Performance Evaluation of Blocking Banyan Switches Supporting Double Priority Traffic

    Page(s): 25 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB) |  | HTML iconHTML  

    In this research, the performance evaluation of two class priority Delta Multistage Interconnection Networks (MINs) is analyzed, using a discrete priority queuing model. All Delta Networks are constructed by special switching elements (SEs) based on an architecture which natively supports two classes of routing traffic. The proposed analytical method which was developed for performance metrics investigation can be applied on any class of Banyan Switches, because the model is independent from their internal link permutations, providing results for all intermediate stages. The analytical method was validated by simulation experiments and the obtained results in the marginal cases of single priority MINs were found to be more accurate as compared with those of three older classic models.The proposed architecture of Delta Networks which have been thoroughly analyzed by our analytical model can be useful in the study and development of communication links that support both voice and data traffic co instantaneously, with good quality of service. View full abstract»

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  • HyTrace Backbone-Assisted Path Discovery in Hybrid Networks

    Page(s): 34 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    HyTrace is a hybrid system providing stable paths between mobile ad hoc nodes. The ad hoc network thereby is organized in clusters where the cluster heads maintain uplinks to a backbone network. The backbone keeps track of available clusters and stable connection between them. The backbone also inter-links different network partitions thus increasing the reliability of the whole system. The underlying Weighted Cluster Path Discovery algorithm still keeps working in settings where no backbone network is available. Broadcasting as well as message exchange between arbitrary nodes is used to further motivate the usefulness of the system. View full abstract»

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  • Optimal Offline TCP Sender Buffer Management Strategy

    Page(s): 41 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB) |  | HTML iconHTML  

    The transmission control protocol (TCP) uses a sliding window in order to enforce flow control. The receiver advertises its available buffer space to the sender, which cannot transmit more data than the advertised space. Transmitted data is first copied from application buffers into TCP buffers and from there it is sent through the network. In this paper we propose a model which characterizes the senderpsilas behavior throughout the duration of a TCP conversation. The model is suitable in the case of powerful, but variably loaded senders, slow receivers, fast connections and moderate amounts of data transmitted. For this model we present an O(nldrlog2n) algorithm which computes the minimum processing time spent by the sender, if the window sizes advertised by the receiver and the senderpsilas load are known in advance. The solution is based on an algorithmic framework for the segment tree data structure, which we introduce in this paper. View full abstract»

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  • Broadband Wireless Access (BWA) Implementation in NGN Network

    Page(s): 47 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1075 KB) |  | HTML iconHTML  

    This paper treats BWA (Broadband Wireless Access) implementation in TK (Telecom of Kosova) NGN network in its efforts to keep the leading position in Kosovapsilas competitive telecommunication market. At the beginning, the architecture of TK NGN network with its corresponding elements is described. Such standard-based, open architecture core network enables the integration of Voice and Multimedia services on a single network infrastructure. Along with first and second phase of core network implementation, TK has analyzed the technical and commercial feasibility of implementation of Broadband Wireless Access as a fastest way to satisfy the growing demands for broadband and voice services in un served and rural areas. The choice of IEEE 802.16, commonly known as WiMAX, proved to be one of the best solutions for that purpose. At the end the implementation of WiMAX in TK NGN is presented showing all advantages of the chosen solution such as high bandwidth, adaptive modulation and coding, fits in of all IP architecture, QoS, security, support of different duplex techniques, etc. View full abstract»

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  • Neural Network Estimation of TCP Performance

    Page(s): 53 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1062 KB) |  | HTML iconHTML  

    TCP remains the protocol of choice for bulk data transfers over the Internet. A range of mathematical approaches were proposed to evaluate the performance of TCP, approaches validated through synthetic or endpoint controlled traffic, typically unsuitable for short-lived transfers or clients with unknown behaviour. This paper aims to overcome these problems by using a supervised adaptive learning approach to build the relationship between TCP performance and the influencing parameters. An earlier study indicated several advantages of the approach, as well as several issues, particularly related to the efficiency of the model on real traces. Comparison against the mathematical models showed that the proposed model provides more accurate estimates for real time traffic without losses, with tests results indicating that the average error of the connection duration, estimated using the proposed model, was 50% smaller than the value obtained using the mathematical approach. View full abstract»

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  • A Distributed Congestion Control Strategy for Differentiated-Services Network

    Page(s): 59 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB) |  | HTML iconHTML  

    In this paper, a new robust congestion control strategy is proposed for a multi-services architecture, namely a Differentiated-Services (DiffServ) network. In virtue of their robustness capabilities, Sliding Mode-based Variable Structure Control (SM-VSC) techniques are utilized to design our proposed controller on the basis of an inaccurate/uncertain Fluid Flow Model (FFM). Developed for an interconnected network as a hop-by-hop distributed control scheme, the proposed algorithm is shown to achieve the desired performance specifications and requirements. Moreover, the error dynamics of the overall time delay dependent network is analytically shown to be L2 stable. View full abstract»

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  • A New Endpoint Admission Control Algorithm in NGN with Improved Network Utilization

    Page(s): 65 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (471 KB) |  | HTML iconHTML  

    In this paper, we propose a new end-point admission control algorithm which helps to manage the traffic efficiently while providing end-to-end service quality. In this algorithm, users are allowed to temporarily use lower service levels in the routers that the requested service level is not currently available. This local degradation preserves the end-to-end service quality in the acceptable level. It may also degrade the end-to-end service level but only if it is acceptable by the application. This degradation may be temporary until the required quality level becomes available. In this way, we can increase the data throughput and also the percentage of admitted calls, which results in higher network utilization. The drawback of this method is the increase in end-to-end delay but this increase can be limited by using appropriate final route selection method at the destination node. View full abstract»

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  • QoS Mapping in TDMA Tree Based Clustered WSN between Accuracy, Density and Bandwidth

    Page(s): 71 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (982 KB) |  | HTML iconHTML  

    Recently, there have been many efforts to develop wireless sensor networks (WSN), but no one can deny the fact that QoS support is still one of the least explored areas in this domain. In this paper, we present QoS support in WSN while highlighting the QoS mapping issue, a complex process in which QoS parameters are translated from level to level and we present a case study of a TDMA tree-based clustered WSN, where accuracy and density on the user level are mapped to bandwidth on the network level. View full abstract»

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  • Reservation Clash Handling to Optimize Bandwidth Utilization in MANETs

    Page(s): 77 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (394 KB) |  | HTML iconHTML  

    Multimedia and real-time applications require bandwidth guarantees, which may be achieved by resource reservation. However, resource reservation in ad-hoc networks is a very challenging task due to the instability of radio channels, nodes mobility and lack of coordination between mobile nodes. Previously proposed reservation MAC protocols like CATA, FPRP and R-CSMA have limitations. They consider that nodes are static and no mobility considerations are taken into account. In this paper, we propose a distributed reservation MAC protocol called Extended R-CSMA (ER-CSMA) to efficiently handle network topology changes due to nodes mobility. We achieved intensive simulations using the NS simulator to evaluate the effectiveness of our protocol. Performance evaluations show that our protocol outperforms the other protocols in terms of throughput and dropping rate. View full abstract»

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  • Quality of Service Management in Heterogeneous Networks

    Page(s): 83 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB) |  | HTML iconHTML  

    This paper presents an approach that aims to provide quality of services (QoS) over heterogeneous Internet domains. The goal is to install and to manage QoS inside each domain and to ensure it on the end to end data path. QoS is a key requirement representing a significant infrastructure upgrade for future networks. Our proposal relies on the multi-service, multi-technology model based on Bandwidth Broker, entity in charge of controlling a given domain. It introduces a concept able to provide QoS in a set of domains using an inter domain signaling protocol. This protocol is used to communicate between Bandwidth Brokers and is independent of the intra-domain routing protocol. Moreover it is independent of the underlying technology and imposes minimal constraints leaving a maximum degree of freedom for users and domains providers to implement specific internal solutions. View full abstract»

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  • Design and Performance Evaluation of a State-Space Based AQM

    Page(s): 89 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (573 KB) |  | HTML iconHTML  

    Recent research has shown the link between congestion control in communication networks and feedback control system. In this paper, the design of an active queue management (AQM) which can be viewed as a controller, is considered. Based on a state space representation of a linearized fluid flow model of TCP, the AQM design is converted to a state feedback synthesis problem for time delay systems. Finally, an example extracted from the literature and simulations via a network simulator NS (under cross traffic conditions) support our study. View full abstract»

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  • Web-Service Solution for Inter-domain QoS Negotiation

    Page(s): 95 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    Development of multimedia services, e.g. video on demand or IPTV and their flow transport over the IP multi-domain networks with quality of services (QoS) guarantees require appropriate management and control of QoS at service and also at the network level. The management and control system must first support cooperation between several independent network domains at service provisioning level while preserving independency of each domain at resource control level. Secondly, the system should integrate various low level mechanisms like QoS routing, resource reservation, admission control. Service Level Agreements and Specifications are used to express inter-entities commitments. This paper presents a web-service approach for implementing the inter-domain SLS negotiation process between network providers (pSLS). The solution is part of an end to end QoS integrated management system through heterogeneous networks defined by the ENTHRONE IST European project. View full abstract»

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  • Analysis of the Relationship between QoS and SNR for an 802.11g WLAN

    Page(s): 103 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    Nowadays, it is very important to study the behavior of the wireless networks due to the variety of applications that make use of this technology. These applications frequently require a minimum QoS in order to work properly and guarantee a good service to the user. This paper aims to find a relationship between signal to noise ratio (SNR) and a 802.11g networkpsilas QoS in terms of latency, packet loss and jitter. It has been created a software tool that obtains different TCP parameters from a file which contains the data about the packet transfer between two nodes in the network. Wepsilave found an instable behavior during the test series because of the nature of wireless networks. Besides, wepsilave pointed out how the delay and the packet loss are affected as the SNR ratio decreases, while jitter has an exponential growth when the signal decreases from 19 to 11 dB. Wepsilave found that the optimal range for most of the real time applications (as VoIP) goes from 34-90 dB, at this range we can find a good QoS in the network performance. View full abstract»

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  • Author index

    Page(s): 109
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