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Wireless Pervasive Computing, 2008. ISWPC 2008. 3rd International Symposium on

Date 7-9 May 2008

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Displaying Results 1 - 25 of 170
  • International symposium on wireless pervasive computing 2008

    Publication Year: 2008 , Page(s): c1
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    Freely Available from IEEE
  • Third international symposium on wireless pervasive computing

    Publication Year: 2008 , Page(s): ii
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    Freely Available from IEEE
  • Proceedings of third international symposium on wireless pervasive computing

    Publication Year: 2008 , Page(s): iii
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 2008
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    Freely Available from IEEE
  • A probabilistic interference and energy aware gradient broadcasting algorithm for wireless sensor networks

    Publication Year: 2008 , Page(s): 1 - 5
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2045 KB) |  | HTML iconHTML  

    This paper addresses the problem of robust transmission of sensed data through a vast field of small and vulnerable sensors towards a sink node. It introduces a routing algorithm called P-GRAB relying on a probabilistic gradient broadcasting framework. Our aim is to improve the GRAB algorithm by accounting for the energy expenditure and the potential of a node for creating interference in the forwarding decision of the algorithm. It is the forwarding stage of P-GRAB that differs from GRAB: once a node has the proper cost for broadcasting a packet, it decides to forward it with a given probability depending on its remaining energy level and its interference potential. We show by simulations that P-GRAB outperforms the GRAB algorithm by providing similar robustness but with much fewer forwarding packets and latency for packet delivery. View full abstract»

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  • A simulation framework for evaluating complete reprogramming solutions in wireless sensor networks

    Publication Year: 2008 , Page(s): 6 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    We propose a simulation framework developed in Simulink for analyzing the performance of code dissemination in wireless sensor networks. The complete solution relies on a three-layer network stack where the LMAC, FixTree and RMD protocols operate in conjunction. For performance evaluation, we use in our simulations the radio link quality model derived from previous field trials. In this way, we can study the impact of real network conditions (e.g. fluctuating link quality, changing neighborhood) on the higher layer protocols and thus verify our design choices in non-idealized circumstances. View full abstract»

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  • Load repartition for congestion control in multimedia wireless sensor networks with multipath routing

    Publication Year: 2008 , Page(s): 11 - 15
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1964 KB) |  | HTML iconHTML  

    Wireless sensor networks hold a great potential in the deployment of several applications of a paramount importance in our daily life. Video sensors are able to improve a number of these applications where new approaches adapted to both wireless sensor networks and video transport specific characteristics are required. The aim of this work is to provide the necessary bandwidth and to alleviate the congestion problem to video streaming. In this paper, we investigate various load repartition strategies for congestion control mechanism on top of a multipath routing feature. Simulations are performed in order to get insight into the performances of our proposals. View full abstract»

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  • Impact of node failure for duty-cycle MAC protocol design in wireless sensor networks

    Publication Year: 2008 , Page(s): 16 - 20
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    The paper presents two failure detection mechanisms, implemented at the MAC layer for nodes used in wireless sensor networks, in order to cope with transient or permanent node failures. Specifically, the failure detection mechanisms are particularly suited for periodic workload applications and MAC protocols that employ four-way handshaking (RTS/CTS/nDATA/nACK) for collision avoidance. One failure detection mechanism is reminiscent of the Hello protocol that is sometimes implemented at the Network layer, and uses a fixed time threshold, while the other mechanism uses the RTS packets count as a metric for determining that a failure has occurred. The paper focuses on the impact of implementing a failure detection mechanism on the performance of the network, in addition to comparing the two failure mechanisms. Moreover, the effect of buffer lengths variations is investigated on the setting of the fault tolerance parameters and on the network performance. View full abstract»

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  • A runtime energy monitoring system for wireless sensor networks

    Publication Year: 2008 , Page(s): 21 - 25
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1908 KB) |  | HTML iconHTML  

    One of the most important issues in the development of wireless sensor networks is energy efficiency. Therefore, it is important to have accurate measurements of the energy consumption of each node.We propose a simple and accurate measurement approach capable to handle this issue. An integrated prototype of our measurement setup was built for the mica2 platform. It can be directly plugged onto the mica2 mote and allows the mote to monitor its energy consumption during runtime. Due to the low costs of our approach it is feasible to employ it in a whole wireless sensor network. The setup shows good accuracy and low power consumption. The mote has access to the measurement setup over the I2C-Bus. Our approach can be easily ported to other wireless sensor network platforms. View full abstract»

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  • Lightweight clustering in wireless sensor-actuator networks on obstructed environments

    Publication Year: 2008 , Page(s): 26 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    Wireless sensor-actuator networks (WSANs) can be useful to cope with the connectivity limitations of sparse networks by allowing powerful and mobile actuators periodically collect data from sensors. We propose a low-overhead algorithm that takes advantage of any potential connectivity present in sensors to form clusters that can expose single collection points, therefore, optimizing actuator data collection rates. No prior knowledge assumptions on the location of sensors, localization algorithms, or environment conditions are made in the design of the algorithm. Environment exploration is introduced as well as self-correcting tour mechanisms. Detailed simulations of high level statistical accuracy support our clustering approach and demonstrate the critical design issues of the algorithm. View full abstract»

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  • Backhaul network based on WiMAX with relays - system level performance analysis

    Publication Year: 2008 , Page(s): 33 - 36
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    In this paper we present the system level performance analysis of the backhaul network based on WiMAX (IEEE 802.16-2004, 2004) with relays. The considered wireless communication system has hexagonal cellular structure, each cell containing a central base station (BS), one or more associated relay stations (RS), all serving the plurality of subscriber stations (SS). The base stations and the relay stations may share the same time-frequency resources when serving subscribers in accordance with various relaying modes having different reuse factor and leading to different level of interference in the deployment. The performance analysis of different relaying modes is presented in this paper. The methodology of individual mode assignment for each subscriber and frame composition is presented along with the analysis of geographical distributions of subscriberspsila preferable relaying modes. Finally, the total cell throughput is evaluated for the case of optimal subscriberspsila assignment to different relaying modes. We show that suggested adaptive relaying technique gives significant increase in the total cell throughput and spectral efficiency. View full abstract»

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  • A cross-layer study on multiple-antenna techniques in wireless backhaul networks

    Publication Year: 2008 , Page(s): 37 - 41
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (174 KB) |  | HTML iconHTML  

    Wireless multi-hop, backhaul networks transfer data traffic from access networks to the wired Internet. Scheduling algorithms for wireless backhaul networks activate multiple simultaneous transmissions, which in turn introduce concurrent interference into the network. Although multiple-antenna techniques have been extensively studied in the literature, not much research for multiple antennas has been received in the backhaul context. In this paper, we investigate the cross-layer performance between various multiple-antenna techniques and backhaul schedulers using physical layer abstraction. Simulation results reveal that with multiple antennas the backhaul network can accommodate a higher density of concurrent links, relative to the network with single antenna. Furthermore, simulation results unfold that the dominant eigenmode transmission and the least square interference cancellation schemes are optimized for noise-limited and interference-limited scenarios, respectively. View full abstract»

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  • TCP optimization in wireless mesh backhaul networks

    Publication Year: 2008 , Page(s): 42 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    This paper deals with the analysis of cross-layer approaches to TCP performance enhancement in wireless multi-hop networks. The work has been carried out within the MEMBRANE project, which aims to design and develop a reconfigurable multi-antenna, multi-hop wireless backhaul network. View full abstract»

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  • MIMO routing with QoS provisioning

    Publication Year: 2008 , Page(s): 46 - 50
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    Multiple-input-multiple-output (MIMO) transceivers can take advantage of random channel fading and multi-path delay spread for multiplying transfer rates (multiplexing gain), improve transmission quality/reliability (diversity gain) at no cost of extra spectrum, or allow the spatial separation of the signals of different transceivers in a multi-user scenario, thus providing a multiple-access gain. View full abstract»

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  • Testbed for wireless Mesh Backhaul Networks MEMBRANE demonstrator

    Publication Year: 2008 , Page(s): 51 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (809 KB) |  | HTML iconHTML  

    Wireless Backhaul mesh networks have attracted attention during the past few years due to their ease of deployment, flexibility and adaptiveness, compared to non-mesh networks. Besides studying and evaluating novel techniques and algorithms for such systems, IST project MEMBRANE aims to develop demonstrators to act as proof of concept and provide an implementation oriented perspective. Two demonstrators are being implemented within the project, addressing different aspects of the proposed system. The first demonstrator focuses on link level cooperative communication for wireless mesh networks and the second focuses on optimized distributed scheduling and routing. This paper briefly describes the techniques and algorithms used in each case and provides the basic design principles of each of the demonstrators. View full abstract»

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  • Relay transmission schemes with multiple antennas for wireless backhaul networks

    Publication Year: 2008 , Page(s): 55 - 59
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB) |  | HTML iconHTML  

    Herein, we propose a novel data splitting algorithm for high throughput relay transmissions using multiple antennas. We also study a two-path relaying protocol using multiple antennas for rural/macro-cell scenarios where a cellular setup is deployed. The performance improvements are demonstrated via simulations. View full abstract»

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  • Capacity of WCDMA multicellular networks under different Radio Resource Management strategies

    Publication Year: 2008 , Page(s): 60 - 64
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB) |  | HTML iconHTML  

    The goal of the study presented in this paper is to investigate the performance of a WCDMA multicellular network which employs antenna arrays (AAs) at the base station (BS) under different Radio Resource Management (RRM) strategies. The performance is evaluated statistically in terms of maximum achievable capacity. A WCDMA system level simulator has been developed which executes independent Monte Carlo (MC) simulations in parallel. Simulation results indicate that there can be significant variations in capacity resulting from the differences in the interference suppression mechanism among the RRM strategies. View full abstract»

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  • Channel State Information enhanced adaptive MC-CDMA

    Publication Year: 2008 , Page(s): 65 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB) |  | HTML iconHTML  

    Future wireless communications will require higher bandwidth and more efficient systems; and MC-CDMA is a good candidate. In MC-CDMA systems, each data undergoes a different channel condition and arrives with a different error rate at the base station. By transmitting message data based on the channel state information (CSI), a new data transmission scheme called ldquochannel state information enhanced multi-carrier CDMArdquo is introduced in this paper. Simulated results have shown that the scheme yields a higher system capacity and better BER than a conventional MC-CDMA at various noise scenarios. View full abstract»

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  • Demodulation of a chaos-based CDMA system using support vector machine

    Publication Year: 2008 , Page(s): 69 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (106 KB) |  | HTML iconHTML  

    This paper presents the algorithm and the result of a novel demodulation technique for a chaos-based CDMA system. Standard CIC filters are applied for interpolating the transmitted signal, in order to retrieve more sample points without increasing the systempsilas bandwidth. Then the original binary message for each user is retrieved by means of a support vector machine demodulator. Simulation results show that this new approach significantly outperforms the conventional method of using matched filters by 7 to 10 dB. View full abstract»

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  • Subcarrier allocation algorithms for multicellular OFDMA networks without Channel State Information

    Publication Year: 2008 , Page(s): 73 - 77
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (147 KB) |  | HTML iconHTML  

    Scope of this paper is to analyse four subcarrier allocation algorithms for multicellular OFDMA networks, namely coordinated, sequential, random and an innovative technique of cell splitting, that uses both random and coordinated subcarrier allocation. Common characteristic of these subcarrier allocation algorithms is that they do not require knowledge of channel state information (CSI) at the transmitter, a fact that leads to more efficient use of available bandwidth, lower algorithmic complexity and faster decision making. The algorithms are studied for an OFDMA multicellular network. Simulation results show that a multicellular OFDMA network is able to provide real broadband wireless access, with offered bit rate to reach 20 Mbps per cell, even without CSI knowledge. View full abstract»

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  • On the problem of joint power and rate control in CDMA ad hoc networks

    Publication Year: 2008 , Page(s): 78 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    In this work, the problem of joint power and rate control (PRC) in CDMA-based ad hoc networks is considered and analyzed. We propose a game theoretic framework for performing efficient power and rate allocation in CDMA ad hoc networks and develop a distributed PRC algorithm for dynamically selecting the optimal neighboring destination, power and rate values. The objective is to maximize properly-defined node utility functions that reflect a tradeoff between actual achieved throughput and power consumption. The PRC algorithm selects opportunistically the destination nodes, by exploiting current channel state information, as expressed by the experienced SINR of the receivers, while it assures the convergence at the gamepsilas unique Nash Equilibrium point in terms of power and rate transmission vectors. We demonstrate the performance of the proposed algorithm in two different network scenarios with respect to the allocated transmission power, received node performance satisfaction, actual achieved throughput and the convergence of the non-cooperative game. View full abstract»

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  • A transceiver scheme for localized DFT spread OFDM (DFT-SOFDM) in time-selective channel

    Publication Year: 2008 , Page(s): 83 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (294 KB) |  | HTML iconHTML  

    The transmission of Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-SOFDM) [4] through a time-selective fading channel with a significant amount of Doppler spread suffers from severe performance degradation. A shift in frequency caused by such channel leads to a loss of orthogonality between users. In this paper, we propose a DFT-SOFDM scheme augmented by MIMO and a new technique to overcome the adverse effects caused by Doppler shift. Repeated Alamouti orthogonal space time block codes are used for transmission of localized MIMO DFT-SOFDM signal. We derive the Minimum Mean-Squared Error (MMSE) combining and estimation scheme that ensures superior BER performance compared to the conventional Maximal-Ratio Receive Combining (MRRC) scheme. The proposed receiver provides a performance gain of 8.6 dB for a 4 users system at BER= 10-3. This gain improves with increased number of users. MRRC gives an error floor due to multiple access interference, which increases with system load. View full abstract»

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  • Bandwidth utilisation for volume-to-volume UWB MIMO communications

    Publication Year: 2008 , Page(s): 88 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (263 KB) |  | HTML iconHTML  

    Previous studies have investigated communications between regions of space and have considered the effect of antenna volume in determining the theoretical capacity of multiple-input multiple-output (MMO) communications systems. In this paper the effects of antenna 1volume on available bandwidth for MIMO systems is considered. It is demonstrated that while higher order modal connections can be established even for small antennas that a fundamental limitation on bandwidth exists. This limitation becomes important for ultra-wide band (UWB) communications systems. View full abstract»

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  • On the influence of carrier frequency offset and sampling frequency offset in MIMO-OFDM systems for future digital TV

    Publication Year: 2008 , Page(s): 93 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    This paper investigates the impact of carrier frequency offset (CFO) and sampling frequency offset (SFO) on the performance of different MIMO-OFDM schemes with high spectral efficiency for next generation of terrestrial digital TV. We analyze particularly orthogonal Alamouti scheme, and non-orthogonal (NO) schemes like VBLAST, linear dispersion (LD) code and Golden code. This analysis gives a global view on the best suitable MIMO-OFDM scheme with respect to CFO and SFO. We show that for high spectral efficiency, Alamouti is more sensitive to CFO and SFO. Moreover, we show that all studied MIMO-OFDM schemes are sensitive to CFO when it is greater than 1% of inter-carrier spacing. Their sensitivity to the SFO is less than to their sensitivity to CFO. View full abstract»

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  • Performance analysis of adaptive low rate differential CSI feedback for MIMO-OFDM systems

    Publication Year: 2008 , Page(s): 97 - 100
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    In situations where the channels are fast changing, systems that require channel state information at the transmitter would need frequent feedback from the receiver. Low rate feedback will be required in these cases, and there have been many proposals on how to compress channel state information to enable a fast feedback to the transmitter. Of these proposed methods, a simple but yet promising way to achieve low rate feedback would be via the use of differential quantization techniques. In this paper, we investigate the use of adaptive delta modulation with givens rotation to encode the CSI in MIMO-OFDM systems. We look at the design of the feedback system, and investigate methods of improving the performance of such systems. View full abstract»

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