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Ubiquitous and Future Networks (ICUFN), 2012 Fourth International Conference on

Date 4-6 July 2012

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Displaying Results 1 - 25 of 120
  • ICUFUN 2012 The Fourth International Conference on Ubiquitous and Future Networks [Front cover]

    Publication Year: 2012 , Page(s): c1
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  • Table of Contents: Contents

    Publication Year: 2012 , Page(s): 2
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  • Committees

    Publication Year: 2012 , Page(s): 3 - 4
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  • ICUFN 2012 Greeting: Message from Organizing Co-Chairs & Message from TPC Co-Chairs

    Publication Year: 2012 , Page(s): 5 - 7
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  • Technical sessions

    Publication Year: 2012 , Page(s): 8 - 14
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  • ICUFN2012 Venue: Mercure Phuket Deevana (former Mercure Patong Phuket)

    Publication Year: 2012 , Page(s): 15 - 16
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  • Analysis of VLC channel based on the shapes of white-light LED lighting

    Publication Year: 2012 , Page(s): 1 - 5
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2208 KB) |  | HTML iconHTML  

    Visible light communications (VLC) uses modern solid-state LEDs to broadcast information. Emerging white-light LEDs allows the combination of lighting and optical wireless communication in one optical source. In this paper, a new shape of LED lighting is proposed for illuminance and data communication. Performance of LED lightings is analyzed under the presence of obstacle. View full abstract»

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  • Received power and SNR optimization for visible light communication system

    Publication Year: 2012 , Page(s): 6 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    The performance of a visible light communication system is greatly affected by LED layout setting. Received power and SNR can be increased or decreased by changing LED placement. However, there is trade-off between received power and SNR. This makes it impossible to design a VLC system that maximizes both received power and SNR simultaneously. In this paper, we find the Pareto-optimal LED layout settings, as well as the performances according to these setting using the SPEA2 multi-objective optimization algorithm. Based on the result of the multi-objective optimization process, one can design a VLC system with optimized performance. View full abstract»

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  • Bi-directional visible light communication using performance-based selection of IR-LEDs in upstream transmission

    Publication Year: 2012 , Page(s): 8 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    In this paper, we propose a novel upstream transmission scheme in bi-directional visible light communication system, which consists of multiple narrow beam infrared light emitting diodes (IR-LEDs). Specifically, we select the best IR-LED among multiple IR-LEDs. The condition and algorithms of selection are provided. A small test-bed is implemented and its results are provided. View full abstract»

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  • Visible light communications with color and dimming control by employing VPPM coding

    Publication Year: 2012 , Page(s): 10 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1037 KB) |  | HTML iconHTML  

    We propose a data transmission scheme using visible light LEDs with color and dimming control. PWM and VPPM coding schemes are used for the control of color and dimming, respectively. The coding procedures and the test results are provided. View full abstract»

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  • Multi-parameters based CSMA/CA for priority in visible light communication

    Publication Year: 2012 , Page(s): 13 - 14
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (373 KB) |  | HTML iconHTML  

    In this paper, we propose a mechanism to support priority MAC for differentiated service applications based on multi-parameters in IEEE 802.15.7 visible light communication (VLC). Multi-parameters mechanism uses four parameters, such as number of backoff times (NB), backoff exponent (BE), contention window (CW), and number of retransmission times (RT) to support the differentiated service applications. We consider beacon-enabled VLC personal area network (VPAN) mode with slotted version for random access algorithm in this paper. Based on a discrete-time Markov chain, we analyze the performance of proposed mechanism under non-saturation environments. The effect of the proposed mechanism on the delay and reliability is explored herein. View full abstract»

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  • Designing adaptive RTS for MadWifi-based WLAN device

    Publication Year: 2012 , Page(s): 15 - 16
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (330 KB) |  | HTML iconHTML  

    Hidden terminal problem in IEEE 802.11 Wireless Local Area Network (WLAN) is known to degrade the performance of WLAN. Though Request-To-Send (RTS) and Clear-To-Send (CTS) can moderate the hidden terminal problem, the use of RTS/CTS without care also deteriorates the performance due to its overhead. Therefore, adaptive RTS algorithms have been studied recently, while most of those can not be implemented in MadWifi-based WLAN device due to the limitation of MadWifi. In this paper, we propose implementable RTS (iRTS) algorithm that adaptively uses the RTS for MadWifi-based WLAN device. Through MadWifi experiments in a communication environment with hidden terminals, we demonstrate that the proposed iRTS outperforms other RTS algorithms. View full abstract»

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  • An energy-efficient routing protocol in wireless sensor networks with holes

    Publication Year: 2012 , Page(s): 17 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB) |  | HTML iconHTML  

    In wireless sensor networks, holes may exist due to uneven deployment, energy exhaustion and physical obstacles. How to establish the energy-efficient routing mechanism in wireless sensor networks with holes is a practical and challenging issues. Many researches employ hole detection algorithm to determine boundary nodes, and then the holes are covered by some virtual shapes such as circles and ellipses. This usually leads to longer path length and more energy exhaustion. In this paper, we propose an energy-efficient routing protocol in wireless sensor networks with holes. Only a few nodes need to determine whether it is a boundary node and a few anchor nodes are used to record the information of holes, thus reducing the energy consumption. In addition, the anchor nodes will be replaced when their residual energy is less than a threshold to prolong the network lifetime. Simulation results demonstrate that our proposed scheme has good performance in terms of energy consumption, control overhead and path length. View full abstract»

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  • Iterative path-loss exponent estimation-based positioning scheme in WSNs

    Publication Year: 2012 , Page(s): 23 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB) |  | HTML iconHTML  

    In wireless sensor networks, the positioning scheme using the received signal strength (RSS) has been widely considered due to its simplicity. Appropriate estimation of path-loss exponent (PLE) between a sensor node and an anchor node plays a key role in reducing position error in this RSS-based positioning. In the conventional researches, a sensor node directly uses the PLEs given by its neighboring anchor nodes, e.g., its nearest anchor node, to calculate its position. However, the PLE between a sensor node and an anchor node is usually different from those given by the anchor nodes, and accordingly results in the distance error in sensor node's positioning. In this paper, we propose the method how a sensor node estimates PLEs from the anchor nodes of interest by itself and calculates its position based on these self-estimated PLEs. In the proposed scheme, a sensor node recalculates PLEs depending on the estimated distances between itself and anchor nodes, and reproduces its position based on the recalculated PLEs. Through simulations, we show that our proposed positioning scheme outperforms the traditional scheme in terms of position error. View full abstract»

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  • Performance evaluation of 802.15.4 Medium Access Control during network association and synchronization for sensor networks

    Publication Year: 2012 , Page(s): 27 - 33
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (607 KB) |  | HTML iconHTML  

    A key aspect of a wireless sensor network is its ability to self-organize and maintain connectivity. Medium Access Control (MAC) protocol manages network self-configuration, which includes establishing a personal area network (PAN), finding a network to associate or disassociate with, and synchronizing if required. Currently, there is limited research that addresses the network initialization phase. This paper provides a performance evaluation of the 802.15.4 MAC during device association and synchronization with the PAN coordinator. Our results show the impact of beacon interval and the number of associating nodes in terms of association time delay and energy consumption in stationary wireless sensor networks. Results illustrate that energy consumption and association time increase with increasing number of nodes associating with a coordinator. Moreover, short beacon intervals consume more energy due to the frequency of beacon frames that nodes have to keep track of to maintain synchronization. However, short beacon intervals reduce the time required for the nodes to associate, in contrast to longer beacon intervals that are undesirable for real time and mobile applications. Furthermore, for longer beacon intervals, BO= 12 to BO=14, there is an abrupt increase in energy consumption as the number of associating nodes increase, even for as few as as four nodes. View full abstract»

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  • Joint energy-balanced and full-coverage mechanism using sensing range control for maximizing network lifetime in WSNs

    Publication Year: 2012 , Page(s): 34 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    Coverage is an important issue that has been widely discussed in wireless sensor networks (WSNs). However, it is still a big challenge to achieve both the purposes of full coverage and energy balancing. This paper considers the area coverage problem for a WSN where each sensor has variable sensing radius. A Weighted Voronoi Diagram (WVD) is proposed as a tool for determining the responsible sensing region of each sensor node according to the remaining energy in a distributed manner. To maximize the network lifetime, techniques for balancing energy consumptions of sensors are further presented. Performance evaluation reveals that the proposed joint energy-balanced and full-coverage mechanism, called EBFC, outperforms the existing studies in terms of network lifetime and degree of energy balancing. View full abstract»

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  • An efficient dispatching mechanism for monitoring disconnected targets in wireless mobile sensor networks

    Publication Year: 2012 , Page(s): 40 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (417 KB) |  | HTML iconHTML  

    Target Coverage is an important issue in Wireless Sensor Networks (WSNs). This work copes with the target coverage problem which dispatches a set of mobile sensors to targets efficiently. Given disconnected targets with different Quality of Monitoring (QoM) in the networks, the mobile sensors are distributed randomly in the networks and are not able to communicate each other since the distance is too far to negotiate. This paper develops an efficient mechanism for mobile sensors dispatching to their proper targets and monitoring those targets with satisfied QoMs. Performance study reveals that the proposed mechanisms outperform existing mechanisms in terms of dispatching time for satisfying the QoMs of all targets and movement cost of all mobile sensors as well as the life time of the monitoring. View full abstract»

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  • Using Tabu-Voronoi clustering heuristics with key management scheme for heterogeneous sensor networks

    Publication Year: 2012 , Page(s): 46 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (607 KB) |  | HTML iconHTML  

    Clustering, routing and security are essential for better performance of any sensor network. Providing inbuilt security to routing algorithms in sensor networks is essential since some of these sensor networks have applications in hostile environments. Researchers work either on a routing algorithm or on security. However, the security should be embedded to the design of a routing scheme. In this paper, initially we divide the given area of interest into Voronoi clusters and then apply a new Tabu heuristic to form more stable clusters. When some event occurs, a new efficient key management technique is applied with improved tree routing algorithm for data routing in heterogeneous sensor networks. The simulation results show that this scheme offers security and uses less computation with substantial savings in memory requirements. Our simulation results show that when Tabu-Voronoi clustering and secure routing scheme are applied together, it is performing better than some existing algorithms. This approach shows higher throughput, fewer network delays, and less energy utilization. View full abstract»

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  • ECU-MAC: A multi-channel MAC protocol for enhancing channel utilization in wireless networks

    Publication Year: 2012 , Page(s): 52 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (609 KB) |  | HTML iconHTML  

    Multi-channel MAC protocols have recently attracted significant attention in wireless networking research because they possess the ability to boost the capacity of wireless ad hoc networks. However, the common challenges in developing multi-channel MAC protocol are the Multi-channel Hidden Terminal (MHT) problem and the Rendezvous problem. This paper proposes an ECU-MAC aiming at efficiently coping with the MHT and Rendezvous problems, while increasing the channel utilization and improving the network throughputs. One novel concept of the proposed ECU-MAC is to exploit the bandwidth resource of ATIM windows of all channels for exchanging data such that the network throughput and channel utilization can be improved. Another key concept of the ECU-MAC is to allow one station to exchange data with multiple stations on several data channels within a beacon interval. Performance evaluation reveals that the proposed ECU-MAC outperforms existing MMAC and DCA protocols in terms of network throughput and average packet delay. View full abstract»

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  • An analytical model for performance evaluation of multi-hop paths in mobile ad-hoc wireless networks

    Publication Year: 2012 , Page(s): 58 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (433 KB) |  | HTML iconHTML  

    Multi-hop communication is commonly observed in mobile ad-hoc wireless networks. It is known that the stability of multi-hop paths formed by mobile nodes is affected by node mobility degree and node density. However, a closed-form model of multi-hop path performance and an in-depth investigation is still missing. In this paper, we derive a analytical model of packet delivery ratio for multi-hop paths from the average packet delivery ratio of each individual link and the distribution of hop count of multi-hop path between an arbitrary source node and a destination node. The corresponding results demonstrate that the proposed approach can provide an efficient method of estimating and evaluating the performance of multi-hop paths in mobile ad-hoc wireless networks. View full abstract»

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  • Performance of an incremental best relay selection with outdated CSI in rayleigh fading channels

    Publication Year: 2012 , Page(s): 63 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    For spectral efficiency and power saving, an incremental best relay selection of a cooperative diversity scheme is proposed. However during the best relay selection process, there may exist a delay between channel estimation and actual data transmission. Consequently, this delay causes outdated channel state information (CSI). We analytically derive the effect of the outdated CSI to an incremental best relay selection diversity scheme. It is noted that the system performance deteriorates with decreasing the value of the correlation coefficient sensitively. When the correlation coefficient reduces from 1 to 0.9, the most performance degradation is denoted. However, the performance degradation is diminished with decreasing the correlation coefficient. View full abstract»

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  • Collaborative watchdogs: A fast and efficient approach to deal with selfish nodes in MANETs

    Publication Year: 2012 , Page(s): 68 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (421 KB) |  | HTML iconHTML  

    Mobile ad-hoc networks (MANETs) rely on network cooperation schemes to work properly. Nevertheless, if nodes have a selfish behaviour and are unwilling to cooperate, the overall network performance could be seriously affected. The use of watchdogs is a well-known mechanism to detect selfish nodes. In this paper we propose a collaborative watchdog approach, which is based on the fast diffusion of selfish nodes awareness. Then, we introduce an analytical model to evaluate the time of detection and the overhead (number of messages) of our collaborative watchdog approach. The results show that a collaborative watchdog is a very efficient approach since the detection time of selfish nodes is reduced, and the overall overhead is very low. View full abstract»

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  • Distributed transmit power control for maximizing end-to-end throughput in wireless multi-hop networks

    Publication Year: 2012 , Page(s): 74 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    Wireless multi-hop network has a solidarity property in which each link consisting of the multi-hop interferes mutually and so the increase of one link's rate results in the decrease of the other links' rate. In the multi-hop link, the end-to-end throughput between source and destination is restricted by the lowest link rate, so the max-min fair allocation on the link rates is an optimal strategy to maximize the end-to-end throughput. In this paper, we verify that if the wireless links have a solidarity property, the max-min fair allocation has all link rates equal, so we propose a transmit power control (TPC) algorithm that decides the transmit power of multi-hop nodes to make all link rates be equal. The proposed algorithm operates in a distributed manner where each node averages the recognized link rates around itself, allocates its transmit power to achieve this average rate, and iterates this operation until all link rates become equal. Intensive simulation shows that the proposed TPC algorithm enables all link rates to converge on the same value and so maximizes the multi-hop end-to-end throughput while decreasing the power consumption of multi-hop nodes. View full abstract»

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  • Joint scheduling and power control for inter-hop interference mitigation in wireless multihop networks

    Publication Year: 2012 , Page(s): 80 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    In wireless multihop network, the inter-hop interference (IHI) is a major factor to deteriorate the end-to-end performances of multihop link. In this paper, we proposed a joint radio resource management with respect to scheduling and power control in order to mitigate the IHI and maximize the resource utilization and the end-to-end rate in the wireless multihop networks. The scheduling algorithm decides the number of orthogonal resources and the transmission time period for simultaneously transmitting links considering the IHI. Moreover, the transmit power control (TPC) algorithm protects the quality of multihop transmission from the collision and severe IHI and optimizes the transmit power and the allocated transmission time jointly. Simulation results show that the proposed schemes using the scheduling and TPC increase the end-to-end rate of multihop link up to 3 times and significantly decrease the total energy consumption of participating nodes, compared to the conventional fixed resource allocation method without TPC. View full abstract»

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  • An adaptive cost function for routing protocols in wireless networks

    Publication Year: 2012 , Page(s): 86 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    Routing protocols have been widely used in wired networks. In wireless environment, however, cost function of the protocol needs to be modified. We propose a new cost function for routing protocol which considers the unstable condition of wireless links: Using BER (Bit Error Rate) of a link, a channel capacity is calculated and is called effective bandwidth. Performance analysis using simulation shows that our cost function can achieve better performances than original one. View full abstract»

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