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The frame collision probability is an important parameter of the performance modeling. This probability has long been assumed as a value that is determined by the channel characteristics and is independent to the medium access control. The validity of this assumption has not been scrutinized. In this paper, we modeled the CSMA/CA mechanism by a closed-loop model through which the analytical expressions...
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Wireless mesh networks (WMN) must often be upgraded as usage demands evolve. This is usually done by adding gateways which serve to increase the backhaul capacity of the network. In this paper we study the problem of this type of capacity augmentation using free-space optical (FSO) backhaul links. A joint clustering and gateway placement problem is formulated which includes the strong rate-distance...
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Flow aggregation has been proposed as a technique to improve the scalability of QoS scheduling in the core of the Internet, by reducing the amount of per-flow state necessary at a router. This is accomplished by aggregating into a single flow multiple flows that share part of the same path to the destination. In its simplest form, flow aggregation is inherently non-work- conserving, that is, it may...
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Energy consumption is of utmost importance in ad hoc wireless networks where battery-operated nodes have limited power resources. Energy consumption is also important in meshed WLAN networks such as emerging home entertainment networks and meshed WiMax metropolitan area networks. So far, it has been advocated that nodes have to operate at the lowest possible power level that keeps the network connected...
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We present the NePTune approach and supporting system architecture for sensor network optimization. NePTune relies on a control loop strategy with performance monitoring, dynamic source code generation, and network reprogramming. We present an application of the system architecture and explore its efficacy in the context of a resource utilization problem - specifically, to minimize the memory consumption...
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Fast and energy-efficient message delivery is an ultimate goal in multi-hop wireless sensor networks. To help achieve this goal, we propose ABC, a simple geographic forwarding scheme capable of bypassing routing holes. ABC is a lightweight and reliable routing protocol in that nodes do not need to set up or maintain routing or neighbor tables; instead, ABC achieves lightweight routing via its "Angled...
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Streaming media applications require acceptable levels of quality of service (QoS). Appropriate rate control mechanism is needed to make streaming media applications to adapt to dynamic network conditions. This paper discusses a window-based weighted-fairness AIMD (WF-AIMD) congestion control algorithm which allows competing flows to share a common bandwidth according to their weights. By making flows...
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In this paper we investigate a special type of denial of service (DoS) attack on 802.11-based networks, namely deauthentication/disassociation attack. In the current IEEE 802.11 standards, whenever a wireless station wants to leave the network, it sends a deauthentication or disassociation frame to the access point. These two frames, however, are sent unencrypted and are not authenticated by the access...
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Multicast is attracting a resurgence of interest because it has a potential to address the explosively growing need for efficient streaming of large-volume Internet content. However, to realize the potential, large-scale multicast distribution requires effective congestion control. In this paper, we design SIM, a protocol that combines three distinct mechanisms (Selective participation, Intra-group...
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Cisco systems' application oriented networking (AON) is an important network element towards building next generation service oriented network. AON processes application- level content and moves far beyond a conventional content-aware Web switch. It creates a novel content delivery platform and allows more sophisticated message-level load balancing mechanisms to be deployed in a switch/router in front...
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The SVC (scalable video coding) extension to the recent video compression standard H.264/MPEG-4 AVC paves the way for video congestion control, by allowing flexible on-the-fly adjustments of the sending rate. We study the interaction between TFRC (TCP-friendly rate control) and application level rate control, and observe that TFRC requires relatively large router buffers to keep packet loss on acceptable...
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Efficient indexing is a key in content-based video retrieval solutions. In this paper we propose a new dynamic indexing scheme based on the kd-tree structure. Video sequences are first represented as traces in an appropriate low dimensional space via luminance field scaling and PCA projection. Then, the indexing scheme is applied to give the video database a manageable structure. Being able to handle...
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This paper derives the formulae for defocus blur parameter from a single image, based upon the line spread function (LSF). To achieve high accuracy and robustness, the over determining strategies are adopted: 1) a number of LSFs on one edge are extracted; 2) more edges in the images are used. The trust-region method is then employed to obtain the optimal estimation of blur parameter. The experimental...
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Quality of service for video and audio transmissions over IP is bound by the best-effort nature of this protocol. The road for achieving optimal behavior for selected flows of traffic includes better controlling and tuning one or more elements of the transmission - the characteristics of the traffic itself or the supporting hardware and software. This tuning may be static or dynamic, profile-based...
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Because of its accuracy, pattern matching technique has recently been applied to Internet security applications such as intrusion detection/prevention, anti-virus, and anti-malware. Among various famous pattern matching algorithms, the Aho-Corasick (AC) can match multiple pattern strings simultaneously with worst-case performance guarantee and is adopted in both Clam antivirus (ClamAV) and Snort intrusion...
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The capacity to ensure the seamless mobility with the end-to-end quality of service (QoS) represents a vital criterion of success in the grid use. In this paper we hence posit a method of monitoring interconnection network of the grid (cluster, local grid and aggregate grids) in order to control its QoS. Such monitoring can guarantee a persistent control of the system state of health, a diagnostic...
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Temporal error concealment (TEC) algorithms do not produce good results in the presence of cut scenes, camera panning or object occlusion in videos due to the lack of a suitable reference frame. Under such circumstances, spatial EC (SEC) may perform better. Thus, EC algorithms should decide adaptively between TEC or SEC. In this paper, we propose an integrated spatio-temporal EC framework which extends...
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There has been a growing interest in wireless sensor networks (WSNs). Considering the limited energy, memory and computational capacity of the sensor nodes, it becomes necessary to ensure rational use of their resources. The fairness and congestion control are also need to be taken into account. It is in this context that a robust routing algorithm with fair congestion control in wireless sensor network...
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In recent contributions [Tennina, S., et al., 2008], [Tennina, S., 2008], we have provided a comparative analysis of various optimization algorithms, which can be used for atomic location estimation, and suggested an enhanced version of the steepest descent (ESD) algorithm, which we have shown to be competitive with well-known distributed localization algorithms in terms of estimation accuracy and...
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Energy management is the key issue in the design and operation of wireless network applications like sensor networks, pervasive computing and ubiquitous computing where the network is primarily driven by battery-powered embedded devices. This paper studies network coding as an energy minimization technique. Network coding reduces the energy consumption by minimizing the number of transmissions required...
