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Systems Communications, 2005. Proceedings

Date 14-17 Aug. 2005

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Displaying Results 1 - 25 of 79
  • 2005 Systems Communications - Cover

    Publication Year: 2005 , Page(s): c1
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  • 2005 Systems Communications - Title Page

    Publication Year: 2005 , Page(s): i - iii
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  • 2005 Systems Communications - Copyright Page

    Publication Year: 2005 , Page(s): iv
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  • 2005 Systems Communications - Table of contents

    Publication Year: 2005 , Page(s): v - x
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  • Preface

    Publication Year: 2005 , Page(s): xi
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  • Committees

    Publication Year: 2005 , Page(s): xii - xvi
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  • A swarm intelligent scheme for routing in mobile ad hoc networks

    Publication Year: 2005 , Page(s): 2 - 6
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    The highly dynamic topology of ad hoc networks and their limited bandwidth made the routing task more difficult. Actually, various kinds of sources (such as voice, video, or data) with diverse traffic characteristics and quality of service requirements (QoS) are multiplexed at very high rates, leads to significant traffic problems such as packet losses, transmission delays, delay variations, etc, caused mainly by congestion in the networks. The prediction of these problems in real time is quite difficult, making the effectiveness of "traditional" protocols based on analytical models questionable. We propose in this paper a state of the art of this problem followed by a solution based on reinforcement learning paradigm that we find more adapted for this kind of problems. View full abstract»

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  • A new approach for supporting QoS in MAC layer over MANETs

    Publication Year: 2005 , Page(s): 7 - 12
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    Currently, the emergence of nomadic applications has raised intense research interest in providing quality of service (QoS) in mobile ad hoc networks (MANETs). An ad hoc network can be considered as an autonomous distributed system that consists of a set of identical mobile nodes that move independently and freely. Each node uses wireless links to communicate with other nodes that reside within its transmission range. In this paper, we propose a new approach for support QoS by the use of priority in the MAC buffer over MANETs. We evaluate the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that this new approach reduces packet loss rate and increases throughput in the MAC layer. View full abstract»

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  • Localized cluster-based re-routing and resource reservation in mobile ad hoc networks

    Publication Year: 2005 , Page(s): 13 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Routing is one of the most important reasons behind clustering in MANETs. However, the frequent changes of the clusterheads affect the performance of the routing protocol. The route between two nodes changes constantly as the clusterhead set changes. Maintaining and minimizing the routes interruptions are two ways of keeping the stability of the network. We claim that the lifetime of a particular route is dependent on all the clusterheads involved in this route. By maintaining the route lifetime, we can keep the network in stable condition as long as possible. Therefore, we propose a localized cluster-based rerouting and resource reservation (LC3R) protocol with packet redundancy over primary and secondary clusterhead chains. This protocol intends to improve the performance of MANETs by increasing the route lifetime to enhance the network stability and developing a reliable cluster-based routing protocol to support the QoS requirements. View full abstract»

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  • Localization in Vehicular Ad Hoc Networks

    Publication Year: 2005 , Page(s): 19 - 25
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    Communications between vehicles constitute a Vehicular Ad hoc Network (VANET). Contrary to MANET in VANET nodes which are vehicles can move with high speed and generally must communicate quickly and reliably. When an accident occurs in a road or highway, alarm messages must be disseminated, instead of ad-hoc routed, to inform all other vehicles. To position a broken vehicle (or vehicle in danger) and locate the vehicles in its vicinity is very important for the safety of the road users. However, vehicles are not necessarily equipped with GPS and even they cannot obtain availability of line of sight access to satellites, particularly when they enter tunnels. In this paper, we propose an improvement to ODAM (optimized dissemination of alarm messages) protocol in order to support localization of GPS-unequipped vehicles. So, the number of vehicles discovering their localisation will be increased. This prevents pile-up of cars when fog, accidents or any other obstacle contributes to the driver safety. Analyses show that the optimal performances of ODAM can be reached even when the rate of GPS-unequipped vehicles is 40% View full abstract»

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  • QoS path selection exploiting minimum link delays in MPLS-based networks

    Publication Year: 2005 , Page(s): 27 - 32
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Real-time multimedia is typically associated with various quality of service (QoS) requirements. Several QoS routing schemes have been proposed to determine a path which has sufficient bandwidth to achieve the desired QoS requirements. Some of these schemes flood nodes with advertisements to obtain information about congestion on the links. Consequently, protocol overhead is of concern in such cases. Other schemes use source routing to determine the shortest routing path, but security is a major concern for allowing source routing in the Internet. To efficiently support QoS over IP networks, traffic engineering (TE) has introduced multiprotocol label switching (MPLS). QoS routing is an essential component of MPLS to maximize network resources. In this paper, we propose an approach that sets up a label switched path (LSP) based on the lowest time delay from the ingress to the egress router using only the ingress, rather than requiring all the nodes in the network to exchange information. Our simulation results show that with our proposed approach, we obtain an improvement in the number of packets delivered and better use of network resources. Furthermore, modification of the MPLS domain is not required. View full abstract»

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  • QoS and energy consumption in wireless sensor networks using CSMA/CA

    Publication Year: 2005 , Page(s): 33 - 39
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    The greatest current challenge in wireless sensor networks consists in building a completely adaptive network without fixed infrastructures and with the smallest energy resources. Applications built upon such networks are various: from telemetry to medical follow-up and from intrusion detection to infrastructure maintenance. Nevertheless, their design requires a large effort to guarantee quasi unlimited lifespan of the network with a minimum QoS (quality of service). In this work, we propose a radio interference model which is combined with a Markovian model of CSMA/CA and permits to estimate power consumption and packet success rate in an IEEE 802.15.4 network. View full abstract»

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  • Efficient handoff decision algorithm using differential RSSI in MPLS-based mobile IP network

    Publication Year: 2005 , Page(s): 40 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    This paper proposes an efficient handoff decision algorithm using differential received signal strength indicator (RSSI) in MPLS-based mobile IP network. MPLS-based mobile IP integrates mobile IP and MPLS. The differential RSSI value is efficient to decide handoff because this value could represent the movement direction of mobile node (MN). In our algorithm, a base station tracks the differential RSSI value of mobile node in overlapped region and releases the reserved bandwidth of MN with the differential RSSI value. As shown by numerical analysis, our algorithm using differential RSSI could increase performance by decreasing handoff blocking probability. View full abstract»

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  • SNR investigation of beam forming in IS-95 CDMA base station receiver

    Publication Year: 2005 , Page(s): 45 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    This paper presents analytical derivations and simulation results for signal-to-noise ratio (SNR) when a linear array antenna is used in a CDMA base station with beam forming (BF) algorithms. The roles of two design factors effecting performance, the direction selectivity of an array antenna and the direction-of-arrival (DOA) accuracy in the BF algorithm, are examined not only for SNR but also to determine the robustness of a BF algorithm due to error factors of spatial scattering of radio waves and DOA. From the study, it is found that there is a trade-off between the SNR and the robustness with respect to these design factors. The trade-off can be used to achieve an economical implementation of the BIT in the CDMA system, which does not have severely deteriorated SNR performance while ensuring its robustness to the error factors. View full abstract»

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  • Advanced mobility models for ad hoc network simulations

    Publication Year: 2005 , Page(s): 50 - 55
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    It is well known that mobility modeling plays an important role when assessing the performance of MANET protocols during a simulation test. This paper presents a tool to generate realistic mobility traces for MANET simulations. A new mobility model called AMADEOS was developed as an extension for the CANUMobisim framework. To model mobility for simulation environments, a new mobility model was created that takes into account obstacles. AMADEOS makes it easy and fast to automatically generate realistic mobility. It allows to edit spatial environments with polygonal obstacles to he used within simulations. It also allows to visualize an animation of the generated mobility traces. A new propagation model based on ray tracing was also implemented as part of AMADEOS. View full abstract»

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  • Modeling of fault-tolerant mobile agents execution in distributed systems

    Publication Year: 2005 , Page(s): 56 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB) |  | HTML iconHTML  

    The reliable execution of a mobile agent is a very important design issue to build a mobile agent system and many fault-tolerant schemes have been proposed. Hence, in this paper, we present FATOMAS, a java based fault-tolerant mobile agent system based on an algorithm presented in an earlier paper. In contrary to the standard "place-dependent" architectural approach, FATOMAS uses the novel agent-dependent approach introduced in the paper. In this approach, the protocol that provides fault tolerance travels with the agent. This has the important advantage to allow fault-tolerant mobile agent execution with out the need to modify the underlying mobile agent platform. We derive the FATOMAS (Fault-Tolerant Mobile Agent System) design which offers a user transparent fault tolerance that can be activated on request, according to the needs of the task, also discuss how transactional agent with types of commitment constraints can commit. Furthermore this paper proposes a solution for effective agent deployment using dynamic agent domains. View full abstract»

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  • Distributed mobility control for fault-tolerant mobile networks

    Publication Year: 2005 , Page(s): 61 - 66
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    Large-scale networks of mobile agents autonomously performing long-term sensing and communication tasks will be foreseeable in the near future. Since nodes in such a system communicate in a multi-hop fashion and the environment may be constantly changing due to the mobility, it is important for such a system to be able to tolerate temporary node failures. Moreover it would be ideal if the communications between nodes are not interrupted while nodes are moving around. In this paper we present a provably correct distributed rendezvous algorithm to achieve both goals by making the underlying communication graph biconnected. The proposed algorithm only requires relative position information of each node and works both synchronously and asynchronously. We further propose for each node a sleep/awake power control schedule in conjunction with the node's mobility strategy to compensate the energy consumption due to the node's movement. View full abstract»

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  • Performance of Secure Ad Hoc Sensor Networks Utilizing IEEE802.11b WEP

    Publication Year: 2005 , Page(s): 68 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (101 KB) |  | HTML iconHTML  

    This paper presents a QoS research study on ad hoc sensor networks from a delay point of view when WEP (wired equivalent privacy) security is enabled or disabled. A queuing model with one queue and two servers is used to estimate the security delays in the traffic between ad hoc sensor nodes. An algorithm is designed to estimate the service time delay and the security time delay based on measured timestamps. The main result is that the security adds a significant delay that may affect future killer applications over ad hoc sensor networks like secure medical application, robotics applications, voice over IP (VoIP) and other delay-sensitive multimedia applications View full abstract»

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  • A new tuning maximum congestion window for improving TCP performance in MANET

    Publication Year: 2005 , Page(s): 73 - 78
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    In terms of improving TCP performance in Mobile Ad Hoc-NETwork (MANET), it is well known that small congestion window size of TCP connection improves TCP performance. We propose a new TCP algorithm to improve TCP performance in MANET. The basic idea of our approach is that TCP receiver estimates the optimum window size and then sets congestion window limit to an optimal value by the advertised window. It is found that our algorithm, using ns-2 simulator, improves TCP performance up to 60% in various topologies in MANET. View full abstract»

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  • A wireless monitoring system for pulse-oximetry sensors

    Publication Year: 2005 , Page(s): 79 - 84
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    This paper presents a wireless medical monitoring system. The system permits to receive and process in a single concentrator node (e.g. a laptop or a simple handheld device) the pulse-oximetry signals from one ore several monitored patients without using any wired infrastructure. The system, which is based on a piconet of Bluetooth sensors, can retransmit the medical signals by WLAN and GPRS. The paper describes the practical application scenarios in which this type of systems could be of great utility. View full abstract»

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  • A simulation framework for evaluating Internet pricing mechanisms

    Publication Year: 2005 , Page(s): 86 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    For several years, researchers in the Internet pricing research area have been proposing various pricing mechanisms. To analyze and evaluate their proposals, they usually make use of analytical based approaches with different assumptions on the environment (sometimes simplistic assumptions); this makes it difficult, or rather impossible, to compare proposals using the same realistic assumptions on the environment. Sometimes, they use also simulations to evaluate their proposals; however, these simulations are very specific and cannot be used for other proposals. We believe that there is a need for a simulation framework that can be used to evaluate different pricing schemes. Such a framework will en able the evaluation of Internet pricing schemes using the same realistic environment (e.g., network and traffic). In this paper, we present the. design and implementation of an Internet pricing simulator using J-Sim, a java-based network simulation tool. The objective of the framework is to ease the process of evaluating Internet pricing schemes. For a proof of concept, we evaluate a pricing scheme, we developed in the past, using the proposed framework. View full abstract»

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  • IDEM: an Internet delay emulator approach for assessing VoIP quality

    Publication Year: 2005 , Page(s): 92 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    Network emulations are imitations of real-time network behavior that help in testing and assessing protocols, and other network related applications in a controlled hardware and software environment. Most of the emulators existing today are hardware implemented emulators. There is a rising demand to emulate the network behavior using a software tool. Our Internet delay emulator (IDEM) is a software tool that captures the network details and reproduces an environment useful for research oriented projects. IDEM is based on bouncers that are distributed over the Internet. The concepts of firewall routing are used in designing IDEM. IDEM supports both TCP and UDP applications. Rigorous testing shows that actual delay in data sent is accurately modeled by IDEM. Advantages of IDEM especially for delay sensitive applications like VoIP are discussed. View full abstract»

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  • Comparative study of MPNT topological models

    Publication Year: 2005 , Page(s): 98 - 103
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    MPNT (Multicast Proxies NeTwork) is an overlay architecture that provides multicast services to unicast or multicast clients. It is multimedia-oriented, as it implements RTP, RTCP and SIP protocols. Nevertheless, it can be used to broadcast any type of data. MPNT is proxy-based, i.e. its nodes are not end-users but proxies: they act like relays for end-users, providing them standard unicast or multicast access. For scalability and adaptivity reasons, these proxies can be interconnected using different topologies. The first implemented topology is spanning tree based. It is very efficient in terms of switching delay (no routing) but the global delay variance can be important. To remedy this, we implemented an alternate hypercube-based topology. Indeed, hypercubes have several interesting properties that ensure a better scalability. Nevertheless, this logical hypercube optimization is valid provided that interconnecting links are comparable. To adapt the architecture to the network heterogeneity, we implemented a hybrid topology exploiting both spanning tree and hypercube advantages. The objective of this paper is to compare these topologies using HYRPAN, a MPNT-specific network simulator we developed for this purpose. View full abstract»

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  • BAP sparsing: a novel approach to MPEG-4 body animation parameter compression

    Publication Year: 2005 , Page(s): 104 - 109
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    The MPEG-4 standard includes support not only for natural video and audio, but also for synthetic graphics and sounds. In the MPEG-4 specifications, body animation parameters (BAPs) and body definition parameters (BDPs) allow virtual bodies and their animation to be compressed using a standard compression pipeline comprising of quantization, predictive encoding and arithmetic coding of these parameters. In this paper, we propose and implement a new stage within the standard prediction-based compression pipeline for the BAPs, termed as BAP sparsing. BAP sparsing compresses a complete block of motion data, consisting of an initial 1-frame followed by subsequent P-frames, required for creating the animation. It exploits the inherent hierarchical structure of the human skeletal model to intelligently drop and modify the P-frames, while preserving animation quality. BAP sparsing is shown to result in superior compression of the BAP data, with negligible loss in the motion animation quality. It is also shown to result in a lower network throughput requirement and fewer CPU cycles on the client end to create the animation. The proposed method is particularly well suited for animation using BAP data. View full abstract»

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  • Unequal error protection for ROI coded images over fading channels

    Publication Year: 2005 , Page(s): 111 - 115
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2632 KB) |  | HTML iconHTML  

    Region of interest (ROI) coding is a feature supported by the Joint Photographic Experts Group 2000 (JPEG 2000) image compression standard and allows particular regions of interest within an image to be compressed at a higher quality than the rest of the image. In this paper, unequal error protection (UEP) is proposed for ROI coded JPEG 2000 images as a technique for providing increased resilience against the effects of transmission errors over a wireless communications channel. The hierarchical nature of an ROI coded JPEG 2000 code-stream lends itself to the use of UEP whereby the important bits of the code-stream are protected with a strong code while the less important bits are protected with a weaker code. Simulation results obtained using symbol-by-symbol maximum a posteriori probability (MAP) decoding demonstrate that the use of UEP offers significant gains in terms of the peak signal to noise ratio (PSNR) and the percentage of readable files. Moreover the use of ROI-based UEP leads to reduced computational complexity at the receiver. View full abstract»

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