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Improving Reliability for Application-Layer Multicast Overlays

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2010年第8期21卷 1103-1116页

作者： Tian, Ye Shen, Hong Ng, Kam-Wing Univ Sci & Technol China Sch Comp Sci & Technol Hefei 230026 Anhui Peoples R China Univ Adelaide Sch Comp Sci Adelaide SA 5005 Australia Chinese Univ Hong Kong Dept Comp Sci & Engn Shatin Hong Kong Peoples R China

Reliability of tree-like multicast overlays caused by nodes' abrupt failures is considered as one of the major problems for the Internet application-layer media streaming service [1]. In this paper, we address this problem by designing a distributed and light-weighted protocol named the instantaneous reliability oriented protocol (IRP). Unlike most of existing empirical solutions, we first define the overlay reliability problem formally, and propose a protocol containing a node joining algorithm (IRP-Join), a node preemption algorithm (IRP-Preempt), and a node switching algorithm (IRP-Switch) for reactively constructing and repairing the overlay, as well as proactively maintaining the overlay. With the formal problem presentation, we set up a paradigm for solving the overlay reliability problem by theoretically proving the effectiveness of our algorithms. Moreover, by comparing IRP with existing solutions via simulation-based experiments and real-world deployment, we show that IRP achieves a better reliability, while incurs fewer structural adjustments on the multicast overlay, thus, providing a superior overall performance.

关键词： Reliability multicast algorithm/protocol design and analysis

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Rate Adaptation in Congested Wireless Networks through Real-Time Measurements

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2010年第11期9卷 1535-1550页

作者： Acharya, Prashanth A. K. Sharma, Ashish Belding, Elizabeth M. Almeroth, Kevin C. Papagiannaki, Konstantina (Dina) Univ Calif Santa Barbara Dept Comp Sci Santa Barbara CA 93106 USA Intel Res Pittsburgh PA 15213 USA

Rate adaptation is a critical component that impacts the performance of IEEE 802.11 wireless networks. In congested networks, traditional rate adaptation algorithms have been shown to choose lower data-rates for packet transmissions, leading to reduced total network throughput and capacity. A primary reason for this behavior is the lack of real-time congestion measurement techniques that can assist in the identification of congestion-related packet losses in a wireless network. In this work, we first propose two real-time congestion measurement techniques, namely an active probe-based method called Channel Access Delay, and a passive method called Channel Busy Time. We evaluate the two techniques in a testbed network and a large WLAN connected to the Internet. We then present the design and evaluation of Wireless cOngestion Optimized Fallback (WOOF), a rate adaptation scheme that uses congestion measurement to identify congestion-related packet losses. Through simulation and testbed implementation we show that, compared to other well-known rate adaptation algorithms, WOOF achieves up to 300 percent throughput improvement in congested networks.

关键词： Wireless communication access schemes algorithm/protocol design and analysis

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Improving Spectral and Temporal Efficiency of Collocated IEEE 802.15.4 LR-WPANs

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2009年第12期8卷 1596-1609页

作者： Kim, Tae Hyun Ha, Jae Yeol Choi, Sunghyun Univ Illinois Wireless Networking Grp Coordinated Sci Labs 459 Urbana IL 61801 USA MZEN Co Ltd Res & Dev Team Seoul 143140 South Korea Seoul Natl Univ Sch Elect Engn Multimedia & Wireless Networking Lab Seoul 151742 South Korea

The number of frequency channels specified for IEEE 802.15.4 low-rate wireless personal area networks (LR-WPANs) does not suffice to operate a variety of collocated WPAN applications that the standard is targeting. To overcome this limit, we introduce Virtual Channel, a novel concept to increase the number of available channels by efficiently managing given spectral and temporal resources. A virtual channel is created by scheduling a superframe and selecting a logical channel. This extends the notion of a channel from spectral domain to spectral and temporal domain. Specifically, we propose a superframe scheduler using throughput estimation (SUTE) of the IEEE 802.15.4 carrier sense multiple access with collision avoidance (CSMA/CA). In addition, nearest vacancy search (NEVS) is proposed, both of which are for temporal efficiency of the collocation. For both spectral and temporal efficiency, virtual channel selector (VCS) is proposed. The simulation results show that a remarkable improvement on the collocation efficiency of IEEE 802.15.4 can be achieved by our proposals. Moreover, this study also reveals the fundamental drawback of the current standard in terms of the collocation efficiency that the beacon interval and superframe duration are adjustable only by exponent parameters.

关键词： algorithm/protocol design and analysis wireless sensor networks standards mobile communication systems scheduling

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Energy-efficient neighbor discovery protocol for mobile wireless sensor networks

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AD HOC NETWORKS 2009年第1期7卷 24-41页

作者： Kohvakka, Mikko Suhonen, Jukka Kuorilehto, Mauri Kaseva, Ville Haennikaeinen, Marko Haemaelaeinen, Timo D. Tampere Univ Technol Inst Digital & Comp Syst FI-33720 Tampere Finland

Low energy consumption is a critical design requirement for most wireless sensor network (WSN) applications. Due to minimal transmission power levels, time-varying environmental factors and mobility of nodes, network neighborhood changes frequently. In these conditions, the most critical issue for energy is to minimize the transactions and time consumed for neighbor discovery operations. In this paper, we present an energy-efficient neighbor discovery protocol targeted at synchronized low duty-cycle medium access control (MAC) schemes such as IEEE 802.15.4 and S-MAC. The protocol effectively reduces the need for costly network scans by proactively distributing node schedule information ill MAC protocol beacons and by using this information for establishing new communication links. Energy consumption is further reduced by optimizing the beacon transmission rate. The protocol is validated by performance analysis and experimental measurements with physical WSN prototypes. Experimental results show that the protocol can reduce node energy consumption up to 80% at 1-3 m/s node mobility. (C) 2007 Elsevier B.V. All rights reserved.

关键词： algorithm/protocol design and analysis Low power design Mobile computing Wireless sensor networks

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An Efficient Directed Localization Recursion protocol for Wireless Sensor Networks

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IEEE TRANSACTIONS ON COMPUTERS 2009年第5期58卷 677-691页

作者： Braga Fernandes de Oliveira, Horacio Antonio Boukerche, Azzedine Nakamura, Eduardo Freire Ferreira Loureiro, Antonio Alfredo Univ Ottawa Sch Informat Technol & Engn PARADISE Res Lab Ottawa ON K1N 6N5 Canada Univ Fed Minas Gerais Dept Comp Sci BR-30123970 Belo Horizonte MG Brazil Univ Fed Amazonas Dept Comp Sci BR-69077000 Manaus Amazonas Brazil FUCAPI Ctr Anal Res & Technol Innovat Fdn BR-69075351 Manaus Amazonas Brazil

The establishment of a localization system is an important task in wireless sensor networks. Due to the geographical correlation between sensed data, location information is commonly used to name the gathered data and address nodes and regions in data dissemination protocols. In general, to estimate its location, a node needs the position information of at least three reference points (neighbors that know their positions). In this work, we propose a different scheme in which only two reference points are required in order to estimate a position. To choose between the two possible solutions of an estimate, we use the known direction of the recursion. This approach leads to a recursive localization system that works with low-density networks (increasing by 40 percent the number of nodes with estimates in some cases), reduces the position error by almost 30 percent, requires 37 percent less processor resources to estimate a position, uses fewer beacon nodes, and also indicates the node position error based on its distance to the recursion origin. No GPS-enabled node is required, since the recursion origin can be used as a relative coordinate system. The algorithm's evaluation is performed by comparing it with a similar localization system;also, experiments are made to evaluate the impact of both systems in geographic algorithms.

关键词： Network architecture and design algorithm/protocol design and analysis wireless sensor networks localization GPS free

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Buffer Coding for Reliable Transmissions over Wireless Networks

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COMPUTER COMMUNICATIONS 2009年第1期32卷 111-123页

作者： Zheng, Zizhan Sinha, Prasun Ohio State Univ Dept Comp Sci & Engn Dreese Labs Columbus OH 43210 USA

In-network caching is a useful technique for reducing latency and retransmission overhead of lost packets for reliable data delivery in wireless networks. However, in-network caching is challenging to implement in memory constrained devices such as RFIDs and sensors, and also in Wireless LAN (WLAN) gateways for large-scale deployments. In this paper we propose a novel technique for management of in-network caches using XOR coding for optimizing the use of limited buffer space in presence of random and burst packet losses. We identify two critical parameters, coding degree and coding distance for the coding scheme. As a case-study we implement our approach over Snoop and evaluate its performance for WLANs. We further propose a self-adaptive algorithm that tunes coding degree on the fly based on the measured coding behavior and packet loss probability. Using simulations in ns-2, we observe that in our simulation settings, when the size of the retransmission buffer in the gateway is less than 16 packets per TCP flow, the throughput can be enhanced by up to 30% for random losses and up to 20% for burst losses. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Wireless communication algorithm/protocol design and analysis

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Cost- and Collision-Minimizing Forwarding Schemes for Wireless Sensor Networks: design, analysis, and Experimental Validation

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2009年第3期8卷 322-337页

作者： Rossi, Michele Bui, Nicola Zorzi, Michele Consotzio Ferrara Ric CFR I-44100 Ferrara Italy Univ Padua Dept Informat Engn I-35131 Padua Italy

The paper presents an original integrated MAC and routing scheme for wireless sensor networks. Our design objective is to elect the next hop for data forwarding by jointly minimizing the amount of signaling to complete a contention and maximizing the probability of electing the best candidate node. Toward this aim, we represent the suitability of a node to be the relay by means of locally calculated and generic cost metrics. Based on these costs, we analytically model the access selection problem through dynamic programming techniques, which we use to find the optimal access policy. Hence, we propose a contention-based MAC and forwarding technique, called Cost- and Collision-Minimizing Routing (CCMR). This scheme is then thoroughly validated and characterized through analysis, simulation, and experimental results.

关键词： Routing protocols distributed applications algorithm/protocol design and analysis dynamic programming wireless sensor networks

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Biased Random Walks in Uniform Wireless Networks

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2009年第4期8卷 500-513页

作者： Beraldi, Roberto Univ Roma La Sapienza Dipartimento Informat & Sistemist I-00100 Rome Italy

A recurrent problem when designing distributed applications is to search for a node with known property. File searching in peer-to-peer (P2P) applications, resource discovery in service-oriented architectures (SOAs), and path discovery in routing can all be cast as a search problem. Random walk-based search algorithms are often suggested for tackling the search problem, especially in very dynamic systems-like mobile wireless networks. The cost and the effectiveness of a random walk-based search algorithm are measured by the excepted number of transmissions required before hitting the target. Hence, to have a low hitting time is a critical goal. This paper studies the effect of biasing random walk toward the target on the hitting time. For a walk running over a network with uniform node distribution, a simple upper bound that connects the hitting time to the bias level is obtained. The key result is that even a modest bias level is able to reduce the hitting time significantly. This paper also proposes a search protocol for mobile wireless networks, whose results are interpreted in the light of the theoretical study. The proposed solution is for unstructured wireless mobile networks.

关键词： algorithm/protocol design and analysis random walks mobile ad hoc networks search algorithms

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Performance Evaluation of Impulse Radio UWB Networks Using Common or Private Acquisition Preambles

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2009年第7期8卷 865-879页

作者： Merz, Ruben Le Boudec, Jean-Yves Deutsch Telekom Labs Networking Grp D-10587 Berlin Germany Ecole Polytech Fed Lausanne Sch Comp & Commun Sci CH-1015 Lausanne Switzerland

For impulse-radio ultrawideband (IR-UWB) networks without global synchronization, the first step for correct packet reception is packet detection and timing acquisition: Before recovering the payload of the packet, the destination must detect that the packet is on the medium and determine when exactly the payload begins. Packet detection and timing acquisition rely on the presence of an acquisition preamble at the beginning of each packet. How this preamble is chosen is a network design issue and it may have quite an impact on the network performance. A simple design choice of the network is to use a common acquisition preamble for the whole network. A second design choice is to use an acquisition preamble that is private to each destination. The throughput with the latter choice is likely to be much higher, albeit at the cost of learning the private acquisition preamble of a destination. In this paper, we evaluate how using a common or private acquisition preambles affects the network throughput. Our analysis is based on analytical modeling and simulations. Using our analytical model, we show that a private acquisition preamble yields a tremendous increase in throughput compared to a common acquisition preamble. The throughput difference grows with the number of concurrent transmitters and interferers. This result is confirmed by simulations. Furthermore, additional simulations on multihop topologies with TCP flows demonstrate that a network using private acquisition preambles has a stable throughput. On the contrary, using a common acquisition preamble exhibits the presence of a compounding effect similar to the exposed terminal issue in IEEE 802.11 networks: The throughput is severely degraded and complete flow starvation may occur.

关键词： Ultrawideband impulse radio modeling techniques algorithm/protocol design and analysis

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Shake Well Before Use: Intuitive and Secure Pairing of Mobile Devices

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2009年第6期8卷 792-806页

作者： Mayrhofer, Rene Gellersen, Hans Univ Vienna A-1010 Vienna Austria Univ Lancaster Dept Comp Lancaster LA1 4WA England

A challenge in facilitating spontaneous mobile interactions is to provide pairing methods that are both intuitive and secure. Simultaneous shaking is proposed as a novel and easy-to-use mechanism for pairing of small mobile devices. The underlying principle is to use common movement as a secret that the involved devices share for mutual authentication. We present two concrete methods, ShaVe and ShaCK, in which sensing and analysis of shaking movement is combined with cryptographic protocols for secure authentication. ShaVe is based on initial key exchange followed by exchange and comparison of sensor data for verification of key authenticity. ShaCK, in contrast, is based on matching features extracted from the sensor data to construct a cryptographic key. The classification algorithms used in our approach are shown to robustly separate simultaneous shaking of two devices from other concurrent movement of a pair of devices, with a false negative rate of under 12 percent. A user study confirms that the method is intuitive and easy to use, as users can shake devices in an arbitrary pattern.

关键词： algorithm/protocol design and analysis ubiquitous computing mobile environments authentication human-centered computing mobile applications

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