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Wireless and Mobile Communications, 2009. ICWMC '09. Fifth International Conference on

Date 23-29 Aug. 2009

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  • [Front cover]

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  • [Title page i]

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  • [Title page iii]

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  • [Copyright notice]

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  • Table of contents

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  • Preface

    Page(s): xi
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  • Committee

    Page(s): xii - xiv
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  • list-reviewer

    Page(s): xv - xvii
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  • A Real-Time Architecture for Automated Wireless Sensor and Actuator Networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Wireless sensor and actuator network (WSAN) are composed of a large number of heterogeneous sensors and actuators. In the automated WSAN, sensors are collaborated to monitor the physical phenomenon in the surveillance field, while the actuators are to collect sensing data, process the data and perform appropriate actions without the existence of central controller. Most WSANs are used in the real-time sensing and reaction systems towards physical environment. In this paper, we propose a real-time architecture for automated WSAN to bind the latency in applications. In the architecture, we present distributed mechanisms for sensor-actuator event reporting and self-aware coordination to maintain the delay bound sensor-actuator communication. And then we present mechanism for ordered multi-event task assignment, and the acting coordination mechanism to provide efficient reaction and execution of the event task in time. Preliminary simulation results are presented to demonstrate the advantages of our solutions. View full abstract»

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  • Fast Resampling and Denoising of Spread Spectrum Signal for Real-Time Wireless Location

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    Narrowband noise is the most effective interference that can make measurement of spread spectrum signal undetected for wireless location. However, current methods for narrowband noise suppression are either very time-consuming or adding distortion to the signal received. In this paper, a fast resampling method and an adaptive Gaussian wavelet filter with optimal time-frequency localisation and variable bandwidth is proposed to suppress single and multiple narrowband noise that interferes with spread spectrum signals in the frequency domain. The filtering and resampling is computationally efficient such that it can be used for real-time implementation. A method by conducting magnitude spectral analysis on received signals in a detection channel is employed to determine which frequency contents in the spectral analysis output contain the interfering narrowband signals. Experimental work has demonstrated that the proposed resampling and wavelet filter reduces narrowband noise efficiently and improves signal to noise ratio (SNR) for peak detection leading to higher accuracy of timing measurement for wireless positioning. View full abstract»

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  • Performance Analysis of a Semi-fixed Mapping Scheme for VoIP Services in Wireless OFDMA Systems

    Page(s): 13 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Informing users about new resource assignments has to be broadcast, thus generating a substantial amount of the mapping overhead that influences the system throughput. In particular, the performance of voice-over-Internet protocol (VoIP) services is seriously affected by the mapping overhead because the VoIP packet size is small. In order to reduce the mapping overhead, a semi-fixed mapping scheme based on the periodicity of VoIP traffic was introduced. However, up to now, the detailed operation and the analysis of the semi-fixed mapping scheme have not been studied. This paper develops analytical and simulation models and evaluates the performance of a semi-fixed mapping scheme for VoIP services in wireless orthogonal frequency division multiple access systems. View full abstract»

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  • Routing in Wireless Networks of Varying Connectivity

    Page(s): 18 - 23
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    We are concerned with routing data in networks where the topology ranges from dense to sparse and mostly connected to mostly disconnected. Connection orientated routing algorithms developed for connected environments fail in disconnected environments, due to the instability of these networks. Similarly, forwarding strategies designed to disseminate data hop-by-hop in disconnected environments fail in connected environments, as they send more packets than is required, resulting in congestion. Our algorithm exploits the re-occuring patterns in connectivity arising from the typical routine structure of day-to-day life. We present a functionality overview of the three components of our proposal: contact driven source routing, disconnection tolerant data forwarding and packet scheduling for energy efficiency. We evaluate our early emulations (simulations in ns-2 with real world data) of disconnection tolerant data forwarding, our results show that source routing can be extended to improve its performance in disconnected environments. View full abstract»

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  • Self-Stabilizing Clustering Algorithm for Ad Hoc Networks

    Page(s): 24 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (235 KB) |  | HTML iconHTML  

    An ad hoc network is a local network that is built spontaneously as devices connect. Instead of relying on a base station or the centralized device, to coordinate the flow of messages to each node in the network, the individual network nodes forward packets to and from each other. So finding a route to a destination can be complexe. The clustering problem consists to partition the network into groups of nodes called clusters. In this paper, we present a self-stabilizing clustering algorithm for ad hoc networks. From any configuration, our algorithm guarantees the network is partitioned in at most D + 2 rounds, where D is the diameter of the network. View full abstract»

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  • Exact Analysis of PCC-OFDM Subjected to Carrier Frequency Offset over Nakagami-m Fading Channel

    Page(s): 30 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    Orthogonal frequency division multiplexing (OFDM) is sensitive to frequency synchronization errors which results in degradation of system performance. Polynomial cancelation coding (PCC) OFDM is introduced to reduce OFDM sensitivity to carrier frequency offset. In this paper, PCC-OFDM performance modeling is considered. An exact closed form expression for symbol error rate (SER) is evaluated for PCC-OFDM subjected to carrier frequency offset. The performance is evaluated over Nakagami-m fading channel. PCC-OFDM improvement as compared to conventional OFDM is emphasized. It is shown that PCC-OFDM outperforms conventional OFDM by about 4 dB in the QPSK modulation at error rate of 10-2 over fading channels with a normalized carrier frequency offset of 0.1. View full abstract»

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  • A Performance Evaluation of a Grid-Enabled Object-Oriented Parallel Outdoor Ray Launching for Wireless Network Coverage Prediction

    Page(s): 38 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1214 KB) |  | HTML iconHTML  

    The use of parallel technologies to solve complex scientific problems has gained increased popularity. The ray optical methods are deterministic propagation approaches that are based on geometrically searching paths between emitter and receivers. They offer higher accuracy than empirical models, but suffer from slow calculations on exhausted rays that have to be searched. In this paper, an object-oriented scheme based on POP-C++ for parallel objects to accelerate outdoor ray launching is described. Performance evaluation is presented to show that this parallel scheme is promising in outdoor wireless propagation modeling. The possibility of running this model in the distributed grid environment is also discussed. Results have shown the great potential of using such a parallel model to predict accurate outdoor wireless propagation scenarios within a short time. View full abstract»

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  • On the Cooperation and Power Allocation Schemes for Multiple-Antenna Multiple-Relay Networks

    Page(s): 44 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (330 KB) |  | HTML iconHTML  

    In this contribution, four different schemes are suggested for multiple antennas multiple relays and their performances are evaluated and compared via computer simulation. At each relay, maximal ratio combining (MRC) in the receiving side and beamforming in the transmitting side are employed. Amplify and forward (AF), and estimate and forward methods (EF) used for single antenna relays are employed here. Then, the power allocation for the relays are carried out by the distributed beamforming adopted from single antenna relay networks with AF scheme. It can be seen that this method works properly for EF for small SNRs as well. View full abstract»

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  • Effect of User Density and Traffic Volume on Uplink Capacity of Multihop Cellular Network

    Page(s): 49 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    The multihop cellular network with mobile relays is of great interest to the emerging standards like IEEE 802.16j, 3GPP-LTE in order to provide wireless broadband access with an increased throughput and coverage. In this context, we focus on the non-real-time services for the uplink direction of a conventional cellular system with multihop transmission using mobile relay stations (RS). Our goal is to derive a per-hop based multihop scheduling algorithm that is easily applicable in a cellular network with high mobility. We have evaluated the performance of multihop communication in an infrastructure based cellular network with high mobility and compared it with the singlehop communication in terms of system throughput and system packet delay. Numerical results demonstrate that multihop communication has greatly improved the performance over conventional cellular system specially when the system has increased user density and higher traffic volume with enhanced mobility. View full abstract»

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  • Enhance the Quality of Experience by Accelerating User Requests in a Multi-wireless-carrier Environment

    Page(s): 54 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB) |  | HTML iconHTML  

    As wireless technologies revolutionize, wireless users can access the ubiquitous networks by multi-mode devices in a multi-wireless-carrier environment. Network selection concept allows person connectivity to applications using the devices and access technologies that best suit user needs. However, the network selection should consider how the bandwidth consumed by the user applications can be well managed in backbone. In this study, we propose a heuristic scheme to accelerate requests from wireless users in a multi-wireless-carrier environment by an efficient backbone management. By fully utilizing the unused network resources, the proposed scheme can enhance the quality of experience from heterogeneous wireless accesses. Our simulation results show that our scheme can grant more bandwidth to the request to shorten the complete time and increase user satisfaction. View full abstract»

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  • Designing and Simulating a Sensor Network of a Virtual Intelligent Home Using TOSSIM Simulator

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    In this paper, we evaluate the features and limitations of Tiny OS mote simulator (TOSSIM), the sensor network simulator in TinyOS systems. The focus is on the applicability of TOSSIM for intelligent home research. As a part of the research work, we designed and implemented a simple sensor network that can be used in a virtual intelligent home. Our conclusions are based on the tests performed with the simulator as well as articles already published on TOSSIM. View full abstract»

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  • Some Analysis of a Cross-Layer Design for a Wireless TCP Network

    Page(s): 64 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    The transport control protocol (TCP) throughput can be decreased in wireless networks. One of the approaches presented in the literature to overcome this problem is cross-layer design. In this paper, we have computed the TCP throughput in a wireless network as a function of the wireless channel bit error rate (BER), the frame size and the retransmission protocol used at the data link layer (DLL). We have proved that TCP throughput can be increased if the segment size in the transport layer is adjusted according to the BER and the DLL protocol. Based on our results, we have proposed a cross-layer scheme in which these two parameters are informed to TCP, so its segment size (which affects the frame size) can be adjusted in order to achieve optimal throughput. View full abstract»

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  • Hierarchical Wireless Network Architecture for Distributed Applications

    Page(s): 70 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper describes a hierarchical wireless network architecture for real time remote coordination and monitoring in distributed applications. The problem of defining a communication architecture keeping in view the constraints imposed by control and monitoring tasks requires a co-design approach. The present framework takes into account the available infrastructure to satisfy the requirements of end to end delay and quality of service for time critical applications communicating over network. View full abstract»

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  • An Analysis of the QoS in the Transmission in 802.11g Networks in the Presence of Bluetooth Interference

    Page(s): 76 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB) |  | HTML iconHTML  

    This paper analyzes the impact of Bluetooth interference on IEEE 802.11g data transmissions in a home environment. The test scenario was composed by two wireless computers associated to an access point and by two cell phones with Bluetooth enabled. Three parameters are analyzed: transmission time, average data transmission rate and number of lost packets. The results obtained showed that Bluetooth transmission affected the IEEE 802.11g one. View full abstract»

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  • An Efficient FPGA Implementation for an DECT Brute-Force Attacking Scenario

    Page(s): 82 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    We present a novel attacking scenario to break into secured DECT-GAP communication. To demonstrate the feasibility of our attack, we propose a brute-force architecture to efficiently recalculate all communication-related shared secrets between the DECT base station and handset. The efficiency of our architecture is demonstrated by a highly pipelined, multi-brute-force-component FPGA implementation. It exploits common weak random number generators implemented at the DECT base stations and a weak authentication scheme between the DECT base stations and their handsets. View full abstract»

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  • Towards Formal Analysis of the Permission-Based Security Model for Android

    Page(s): 87 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    Since the source code of Android was released to the public, people have concerned about the security of the Android system. Whereas the insecurity of a system can be easily exaggerated even with few minor vulnerabilities, the security is not easily demonstrated. Formal methods have been favorably applied for the purpose of ensuring security in different contexts to attest whether the system meets the security goals or not by relying on mathematical proofs. In order to commence the security analysis of Android, we specify the permission mechanism for the system. We represent the system in terms of a state machine, elucidate the security needs, and show that the specified system is secure over the specified states and transitions. We expect that this work will provide the basis for assuring the security of the Android system. The specification and verification were carried out using the Coq proof assistant. View full abstract»

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  • A Study on Security Framework for Ambient Intelligent Environment (ISyRAmISF: ISyRAmI Security Framework)

    Page(s): 93 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    ISyRAmI (intelligent systems research for ambient intelligence) is an artificial intelligence oriented methodology and architecture for the development of ambient intelligence (AmI) systems. The ISyRAmI architecture considers the following four modules: data/information/knowledge acquisition; data/information/knowledge storage, conversion, and handling; intelligent reasoning; and decision support/intelligent actuation. However, because there is no security module in ISyRAmI, it was analyzed as weak by attacks like DDoS, sniffing, fake server, fake context, malicious code, DNS attacks, and routing attacks etc. For example, if the attackers send their fake contexts in ISyRAmI environment, some ISyRAmI devices may reply the bad information to users, i.e., to send their contents named as spam, to get userpsilas information by attackers fake server, sometimes, too many attackerpsilas contexts may lead to server down like damage of DDoS attacks, etc. Finally, these kinds of attacks make polluted results in ISyRAmI. ISyRAmI aims to support user next steps through an instantly adaptation to the dynamic environments, to achieve that is mandatory to include a security module in the ISyRAmI methodology and architecture. In this paper, we propose a security framework to the ISyRAmI approach. View full abstract»

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