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Communications, 2007. ICC '07. IEEE International Conference on

Date 24-28 June 2007

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Displaying Results 1 - 25 of 1082
  • 2007 IEEE International Conference on Communications

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  • Copyright - ICC 2007

    Page(s): ii
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  • Welcome - Executive Chair

    Page(s): iii
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  • Welcome - TPC Co-Chairs

    Page(s): iv
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  • Welcome - Gordon Brown

    Page(s): v
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  • Welcome - Sir Sean Connery

    Page(s): vi
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  • Committees

    Page(s): vii - xx
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  • Table of contents

    Page(s): xxi - xxxiii
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  • Author index

    Page(s): 6545 - 6559
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  • A Dynamic Service Level Negotiation Mechanism for QoS Provisioning in NGEO Satellite Networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    Satellite communication systems exhibit important and unique features that qualify them to be an integral part of a global ubiquitous information system. Given the universality of the Internet protocol (IP), traffic over satellite network is expected to be all IP. Success of these all-IP satellite systems depends on their abilities to guarantee QoS. QoS provisioning has been a hot topic in terrestrial wired networks. It has been, however, highly overlooked in wireless networks. An efficient QoS provisioning in wireless networks in general, and in satellite networks in particular, can be possible only with the development of new schemes that are able to dynamically (re)negotiate service levels in an adaptive manner to changes in network conditions upon handoff occurrences. This paper surveys major dynamic service level negotiation schemes proposed for terrestrial wireless networks and discusses their limitations when applied to satellite networks. As a solution, a dynamic service level negotiation scheme specifically tailored to satellite networks is portrayed. Comparison of the proposed scheme to other dynamic negotiation approaches, via a qualitative and quantitative analysis, is also presented. View full abstract»

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  • Performance Study of Bandwidth Allocation Techniques for QoS-Constrained Satellite Networks

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (318 KB) |  | HTML iconHTML  

    The paper analyzes the performance of the bandwidth allocation process over satellite communication systems in presence of specific quality of service (QoS) requirements. The reference allocation algorithms considered are based on multi-objective programming (MOP) and are called "Utopia minimum distance" (UMD), "constrained Utopia minimum distance" (CUMD) and "QoS point minimum distance" (QPMD). The rationale under the algorithms is considering bandwidth allocation as a competitive problem where each earth station has its cost function that needs to be minimized by penalizing the others. The performance of the techniques described has been evaluated over a faded channel by using TCP/IP traffic. The analysis is carried out analytically by comparing the efficiency of the MOP based techniques with other approaches treated in the literature and by evaluating the effects of possible QoS specifications. View full abstract»

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  • Performance of VoIP using DCCP over a DVB-RCS Satellite Network

    Page(s): 13 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB) |  | HTML iconHTML  

    The datagram congestion control protocol (DCCP) is a new IETF-defined transport protocol for Internet multimedia. The DCCP congestion control identifier 4 (CCID4) was specifically designed to support the stream of small packets generated by applications such as voice over IP (VoIP). This uses equation based congestion control. The long round trip delay when the path includes a satellite link could therefore degrade the performance of VoIP. In this paper, we analyze using simulation the performance of VoIP using CCID4 over a DVB-RCS network. We also analyze the different variants of CCID4 that have been proposed. The paper concludes that the current algorithm of CCID4 suffers for paths with appreciable delay when used to support voice calls with a bursty nature. The results show that these effects are only partially mitigated by the currently proposed variants of CCID4. View full abstract»

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  • Buffer Occupancy-Based CAC in Converged IP and Broadcasting Networks

    Page(s): 19 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (662 KB) |  | HTML iconHTML  

    This paper introduces a buffer occupancy-based admission control mechanism aimed to counter link congestion while fairly sharing the bandwidth in converged IP and broadcasting networks. The proposed connection admission control (CAC) scheme favors fairness and downlink bandwidth sharing between different served satellite terminals (sub-networks) in presence of congestion events. Our CAC is intended to overcome major obstacles such as: instantaneous link capacity (available bandwidth) assessing, high computational complexity in flows characterization, and use of traffic descriptors with new flows. This makes the scheme more suitable for DVB-S2 environments where the link capacity may vary as consequence of physical layer adaptive coding/modulation during noisy periods. Simulations results show that the proposed system can avoid uplink and downlink congestion and share fairly the bandwidth between satellite terminals. Further, our CAC minimize the probability of congestion events while still achieving high resources utilization. View full abstract»

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  • On-Demand Routing in LEO Satellite Systems

    Page(s): 26 - 31
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (233 KB) |  | HTML iconHTML  

    In this paper, a location-assisted on-demand routing (LAOR) protocol for low earth orbit (LEO) satellite systems is proposed and evaluated. This protocol can be viewed as a variant of the well-known ad-hoc on-demand distance vector (AODV) routing protocol, tailored to the requirements imposed by the characteristics of LEO satellite systems' topology. The LAOR protocol is assessed for different link-cost metrics and compared to centralized routing protocols proposed in the literature thus far. Simulation studies further document and confirm the positive characteristics of the proposed protocol. View full abstract»

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  • M-gated Scheduling in Wireless Networks: Performance and Cross-layer Design

    Page(s): 32 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    E-limited (or K-limited) scheduling is attractive because its performance is close to that of the exhaustive scheduling which is proven to be the optimal polling scheme for symmetric systems (same traffic offered to all queues) by some researches. If the parameter K is chosen properly, E- limited scheduling can avoid the unfairness, which is an inherent problem for the exhaustive service on a short time scale. In this paper, M-gated scheduling which is superior to E- limited is proposed to be used in wireless networks. With the method of the imbedded Markov points and the probability generating function, we develop a model for this novel scheduling algorithm with vacations, where the vacations represent the time periods in which the resource sharing mechanism used is a non-polling mode. The theoretical analyses are consistent with the simulation results. We also use the derived quality of service parameter as the basis for cross- layer design and then analyze its performance. View full abstract»

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  • Performance Analysis of Adaptively-Routed Wormhole-Switched Networks with Finite Buffers

    Page(s): 38 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (338 KB) |  | HTML iconHTML  

    The use of adaptively-routed wormhole switched k-ary n-cubes has been motivated by the high path diversity provided by the rich topology of this family of interconnection networks. Due to its insensitivity to message destination, adaptive wormhole switching has been an attractive design alternative not only in networks suggested for contemporary multicomputers but also in the new Network-on-Chip and System-on-Chip architectures. Although analytical performance models for wormhole switched networks have been widely reported in the literature over the past two decades, the majority of these models have unrealistically assumed negligible buffering capacity at each switching element of the network. This paper proposes the first analytical model to assess the performance of adaptively-routed wormhole-switched k-ary n-cubes with finite size buffers. The new model can also accounts for the use of any number of virtual channels in order to further improve system performance. The model is validated by means of an event-driven simulator and experiments show close agreement between model predictions and simulator results. View full abstract»

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  • Achieving High Goodput Performance in Mars Missions through Application Layer Coding and Transmission Power Trading

    Page(s): 44 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (341 KB) |  | HTML iconHTML  

    Transferring data reliably from Mars to Earth stations is becoming an appealing challenge in the design of interplanetary networks. In this view, the use of CCSDS-based protocols along with erasure codes is a promising candidate for mitigating the performance degradation due to large propagation delays and high packet loss rates. Besides, the constraints imposed on the transmission power and on the available link bandwidth introduce further challenges to the design of the telecommunication system. In this paper, the benefits brought are investigated by tuning properly erasure code rate at the upper layers, pointing out the performance gain in terms of goodput performance and analysing power consumption and bandwidth usage issues, as well. View full abstract»

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  • CLAPS: A Cross-Layer Analysis Platform for P2P Video Streaming

    Page(s): 50 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (390 KB) |  | HTML iconHTML  

    Peer-to-peer (P2P) networks are emerging as an interesting alternative to media streaming delivery with respect to content delivery networks (CDN). Although several P2P protocols have been proposed to support video streaming with an adequate degree of quality of service (QoS), a critical point today is how to evaluate them and optimize their parameters. The difficulty lies in the fact that the behavior of the P2P overlay network and the one of the underlying packet network are closely related and need to be analyzed simultaneously. Ad-hoc simulators for each P2P architecture have been proposed but they neglect the interactions between peers and the underlying network. This paper proposes a new approach to P2P video streaming performance analysis and system design which provides a very accurate cross-layer simulation of the real behavior of P2P clients over TCP/IP networks. A fluid-flow approach has been adopted to simulate the behavior of the network elements supporting an emulated overlay network consisting of real implementations of P2P clients. The P2P SplitStream video streaming protocol is considered as a case study to demonstrate that the tool is able to capture performance parameters at both the overlay (e.g. inter description synchronization) and packet network levels (e.g. traffic source round-trip time and router queue behavior). View full abstract»

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  • Performance Evaluation of Network Systems Accounting for User Behaviors

    Page(s): 57 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (531 KB) |  | HTML iconHTML  

    Considering user behaviors in the performance evaluation of mobile networks is crucial as traffic generation in such networks is highly dependent on mobility and communication activities of mobile users. This paper presents a simulator that can faithfully simulate user behaviors together with the target network system. The following three components have been implemented in a network simulator in order to model realistic user behaviors: (i) a function of loading geographical data for the target area, (ii) a pedestrian mobility model in which users walk along streets based on the given geographical data, and (iii) a communication behavioral model, which accounts for correlations between user profiles and their communication activities. Simulation of a mobile network system is performed and shown that the simulator replicates realistic behaviors of individual users, and also that the user behaviors do influence the predicted overall system performance. This indicates the importance of accounting for user behaviors in mobile network system evaluation. View full abstract»

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  • Predicting User-Perceived Quality Ratings from Streaming Media Data

    Page(s): 65 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    Media stream quality is highly dependent on underlying network conditions, but identifying scalable, unambiguous metrics to discern the user-perceived quality of a media stream in the face of network congestion is a challenging problem. User-perceived quality can be approximated through the use of carefully chosen application layer metrics, precluding the need to poll users directly. We discuss the use of data mining prediction techniques to analyze application layer metrics to determine user-perceived quality ratings on media streams. We show that several such prediction techniques are able to assign correct (within a small tolerance) quality ratings to streams with a high degree of accuracy. The time it takes to train and tune the predictors and perform the actual prediction are short enough to make such a strategy feasible to be executed in real time and on real computer networks. View full abstract»

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  • Application-Aware Topology Formation Algorithm for Peer-to-Peer Networks

    Page(s): 73 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    When constructing an unstructured P2P topology, one should consider the application running on top of it in order to achieve a good performance for the whole P2P system. It is not enough only to consider the "topology" objective when forming an overlay such as minimizing a P2P network diameter because it does not achieve a good performance for the whole P2P system. For example, minimizing a P2P network diameter may overload some peers under a flooding search application because of their excess connections. Therefore, one should consider the behavior of the application on top of the topology such that the topology can adapt itself in order to benefit the application. To fulfil this objective, we propose an application-aware topology formation algorithm which can be "tuned" so as to achieve load-balancing for a spectrum of P2P applications. Furthermore, we provide a very detailed analytical model to understand the behavior of our algorithm under any heterogeneous environment. The analytical results are validated by the simulations. View full abstract»

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  • Optimal Bandwidth Provision at WiMAX MAC Service Access Point on Uplink Direction

    Page(s): 80 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    In this paper, the IEEE 802.16 protocol is investigated with respect to the bandwidth provision problem arising at the medium access control (MAC) layer. The aim is to optimally tune the resource allocation to match QoS requirements. Traffic flows are originated at network layers overlying the 802.16 protocol stack. This leads to the investigation of a novel control algorithm, suited to optimal bandwidth allocation and call admission control in the presence of statistically heterogeneous flows. Specific implementation details are provided to match the application of the control algorithm using the regular 802.16 request-grant protocol. Simulation results validate the proposed approach. View full abstract»

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  • QoS Constrained VoIP Scheduling in 1xEV-DO

    Page(s): 86 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (146 KB) |  | HTML iconHTML  

    A QoS constrained scheduling framework is presented and evaluated for VoIP traffic. QoS factors such as frame error rate, delay, codec related quality factors are added to the proportional fair scheduler in different manners to enhance the scheduler support for real-time traffic, like VoIP. Simulations show that the new scheduler improves the link level quality/fairness and the system capacity. View full abstract»

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  • On connectivity and capacity of wireless mesh networks

    Page(s): 91 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (357 KB) |  | HTML iconHTML  

    Wireless Mesh Networks represent an interesting technology due to their reliability, broad coverage and relatively easy and inexpensive scalability. The architecture is mainly a hybrid solution between ad-hoc and infrastructure networking, where each node potentially acts as a relay, forwarding traffic generated by other nodes. Even if solutions are already available, many research topics have yet to be investigated, as no theoretical studies are available to determine the performance of such networking paradigm. In this work, we aim at providing mathematical expressions for connectivity and cumulative capacity of a mesh network on the basis of the network configuration, in order to provide guiding principles in mesh networks' design and development. An analytical approach is used in determining the connectivity probability, while the "bottleneck collision domain" concept is adopted to estimate capacity. The framework is further validated through comparison with simulation results. View full abstract»

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  • Distributed Power Control in Multihop Ad Hoc CDMA Networks

    Page(s): 96 - 101
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    In this paper, we propose a distributed power control algorithm for multihop ad hoc CDMA networks. The algorithm attempts to maximize the QoS of each user as well as a global network utility, given a set of routes and link schedules. By defining the local objective of each node as a summation of its own utility and that of the "bottleneck" nodes in its vicinity, users are considered partially cooperative. Since the overall QoS of a single flow is determined by the minimum received QoS among all of its subflows, the global network utility is defined only based on these bottleneck QoS's for each user. View full abstract»

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