On Distinguishing Relative Locations with Busy Tones for Wireless Sensor Networks

[[abstract]]Bounding-box mechanism is a well known low-cost localization approach for wireless sensor networks. However, the bounding-box location information can not distinguish the relative locations of neighboring sensors, hence leading to a poor performance for some applications such as location-aware routing. This paper proposes a Distinguishing Relative Locations (DRL) mechanism which uses a mobile anchor to broadcast tones and beacons aiming at distinguishing the relative locations of any two neighboring nodes. Experimental study reveals that the proposed DRL mechanism effectively distinguishes relative locations of any two neighboring nodes and hence significantly improves the performance of location-aware routing in wireless sensor networks (WSNs).[[conferencetype]]國際[[conferencedate]]20100523~20100527[[iscallforpapers]]Y[[conferencelocation]]Cape Town, South Afric

TCWTP: Time-Constrained Weighted Targets Patrolling Mechanism in Wireless Mobile Sensor Networks

[[abstract]]Target coverage problems have received much attention in recent years. In a large monitoring environment where targets are distributed over an entire monitored region, deploying static sensors leads to high hardware costs because a high number of sensors may be required to achieve network connectivity. This paper considers the target-patrol issue where a set of mobile data mules (DMs) are dispatched to efficiently patrol the given targets under a predefined time constraint. The targets are assigned weights indicating their importance, where more important targets should be visited more frequently by the DMs. Accordingly, this paper proposes a time-constrained weighted targets patrolling (TCWTP) algorithm for locally constructing efficient patrol paths, thereby ensuring globally stable intervals between visits to all target points. A performance analysis revealed that the proposed TCWTP mechanism outperforms existing works in terms of the average interval between visits, quality of monitoring satisfaction ratio, and monitoring fairness ratio.[[notice]]補正完畢[[booktype]]紙

The k-Barrier Coverage Mechanism in Wireless Visual Sensor Networks

[[abstract]]Wireless Visual Sensor Networks (WVSNs) consist of a set of camera sensor nodes each of which equips with a camera and is capable of communicating with the other camera sensors within a specific distance range. As an extension of wireless sensor networks (WSNs), the WVSNs can provide richer information such as image and picture during executing targets monitoring and tracking tasks. Since the sensing area of each camera sensor is fan-shaped, existing barrier-coverage algorithms developed for WSNs cannot be applied to the WVSNs. This paper is considering to address the k-barrier coverage problems in WVSNs and to propose a barrier-coverage approach aiming at finding a maximal number of distinct defense curves with each of which consists of as few camera sensors as possible but still guarantees k-barrier coverage. Compared with the related work, experimental study reveals that the proposed k-barrier coverage mechanism constructs more defense curves than the k-barrier coverage and the number of camera sensors participating in each defense curve is smaller.[[conferencetype]]國際[[conferencedate]]20120401~2012040

Path Guiding Mechanisms for a Mobile Anchor Improving or Balancing Location Accuracies of Static Sensors in WSNs

[[abstract]]Location information is of utmost importance for most applications in wireless sensor networks. Recent localization schemes have been categorized into range and range-free based techniques. Obvious inclination is towards range free algorithms since they do not rely on special hardware that would be required in range based algorithms. In the most proposed range-free algorithms, nodes estimate their location using the geometric constraints imposed by the location of a mobile anchor. However, there is no discussion on how the mobile anchor moves so that the maximal location accuracies of all sensor nodes can be obtained with the constraint of energy consumption of a mobile anchor. This paper assumes that traditional range-free algorithms have been executed for a certain time period and the deployed sensors are with different location accuracies. We propose path guiding mechanisms that sensor nodes cooperatively guide the mobile anchor moving along an efficient path which can maximize the improvement of location accuracies or minimize the accuracy differences for all sensor nodes in a given WSN. Experimental study reveals that the proposed path guiding mechanisms effectively guide the mobile anchor moving along the efficient path and thereby saves time and energy consumptions for improving or balancing the location accuracies of all sensor nodes.[[conferencetype]]國際[[conferencedate]]20081014~20081017[[iscallforpapers]]Y[[conferencelocation]]Montreal, Canad

Patrolling Mechanisms for Disconnected Targets in Wireless Mobile Data Mules Networks

[[abstract]]This paper considers the target patrolling problem which asks a set of mobile data mules to efficiently patrol a set of given targets. Since the time interval (also referred to visiting interval) for consecutively visiting to each target reflects the monitoring quality of this target, the goal of this research is to minimize the maximal visiting interval. This paper firstly proposes a basic algorithm, called Basic (B-TCTP), which aims at constructing an efficient patrolling route for a number of given data mules such that the visiting intervals of all target points can be minimized. For the scenario containing weighted target points, a Weighted-TCTP (W-TCTP) algorithm is further proposed to satisfy the demand that targets with higher weights have higher data collection frequencies. By considering the energy constraint of each data mule, this paper additionally proposes a RW-TCTP algorithm which treats energy recharge station as a weighted target and arranges the data mules visiting the recharge station before exhausting their energies. Performance study demonstrates that the proposed algorithms outperform existing approaches in terms of visiting intervals of the given targets and length of patrolling path.[[conferencetype]]國際[[conferencedate]]20110913~20110916[[conferencelocation]]Taiwa

PCF: on exploiting spatial reuse and power conservation opportunities with power control and fairness mechanism for 802.11 WLAN

[[abstract]]Exploiting spatial reuse opportunities allows more parallel transmissions and improve the throughput of wireless networks. Power control is one of the major mechanisms used to exploit both spatial reuse and power conservation opportunities. Increasing the transmitting power prevents the receiver from interference but consume power and create additional interference to other communicating nodes. On the contrary, reducing the transmitting power reduces the interference to other communicating pairs and save sender's power consumption, but result a lower SNR (signal to noise ratio) at receiver side. This article presents power control MAC protocol to exploit the spatial reuse and power conservation opportunities for 802.11 wireless LAN. The proposed protocol evaluates the interference and adopts power control mechanism on both sender and receiver sides, trying to allow more communications proceeding simultaneously. In addition, a fairness control mechanism is also proposed to reduce the average communication delay and alleviate the packet lost phenomenon. Performance results reveal that the proposed protocol improves the throughput and power consumption of WLAN while the fairness among communicating pairs can be maintained.[[conferencetype]]國際[[conferencedate]]20050306~20050308[[booktype]]紙

TARP: a traffic-aware restructuring protocol for Bluetooth radio networks

[[abstract]]Bluetooth is a well-known wireless technology designed for wireless personal area networks (WPAN). The Bluetooth device randomly searches and connects with other devices using the inquiry/inquiry scan and the page/page scan operations, resulting an uncontrolled scatternet topology. The unpredictable scatternet topology usually raises the problem of redundant traffic and causes inefficient communications. A traffic-aware restructuring protocol (TARP) is presented for partially restructuring a piconet or neighboring piconets by applying role switch mechanism. According to the recent routes and their traffic pattern, the TARP adjusts piconet structure by selecting the proper master from devices of a piconet and switches proper devices of neighboring piconets to reduce the route length and thus improve the power and bandwidth consumptions and transmission delay. Performance results show that TARP significantly improves network performance by reducing traffic load and power consumptions[[conferencetype]]國際[[conferencedate]]20050911~20050914[[booktype]]紙本[[conferencelocation]]Berlin, German

TARP: A traffic-aware restructuring protocol for Bluetooth radio networks

[[abstract]]Bluetooth is a low-cost and short-range wireless communication technology. The Bluetooth device randomly searches and connects with other devices using the inquiry/inquiry scan and the page/page scan operations, resulting an uncontrolled scatternet topology. The unpredictable scatternet topology usually raises the problem of redundant traffic and causes inefficient communications. A traffic-aware restructuring protocol (TARP) is presented for partially restructuring a piconet or a pair of two neighboring piconets by applying role switch mechanism. The proposed TARP mainly consists of intra-piconet and inter-piconet restructuring protocols. According to the recent routes and their traffic load information, the intra-piconet restructuring protocol adjusts piconet structure by selecting the proper device to play a master role of a piconet and applies takeover operation to rapidly restructure the piconet topology. The inter-piconet restructuring protocol exchanges devices of two neighboring piconets to reduce the route length and thus improve the power and bandwidth consumptions and the end-to-end transmission delay. Performance results reveal that the proposed restructuring protocols reduce path length of recent routes and save power consumption, thus significantly improve the performance for a given connected scatternet.[[incitationindex]]SCI[[conferencelocation]]Berlin, German

On Providing Temporal Full-Coverage by Applying Energy-Efficient Hole-Movement Strategies for Mobile WSNs

[[abstract]]This paper considers a mobile WSN that contains a big hole but there exists no redundant mobile sensor to heal the hole. To achieve the temporal full-coverage purpose or enhance the tracking quality, three distributed algorithms are proposed for moving the existing big coverage hole to a predefined location. Firstly, the sink chooses a promising direction for hole-movement. Then the basic, forward-only and any-direction movement mechanisms are proposed to move the hole along the promising direction in a manner of minimizing the total power consumption or balancing the energy consumption of the given WSN. Simulation results reveal that the proposed hole-movement mechanisms enhance the coverage of WSN and balance the energy consumption of mobile sensor nodes.[[conferencetype]]國際[[conferencedate]]20070311~20070315[[iscallforpapers]]Y[[conferencelocation]]Kowloon, Hong Kon

OFRD:Obstacle-Free Robot Deployment Algorithms for Wireless Sensor Networks

[[abstract]]Node deployment is an important issue in wireless sensor networks (WSNs). Sensor nodes should be efficiently deployed in a predetermined region in a low cost and high coverage quality manner. Random deployment is the simplest way for deploying sensor nodes but may cause the unbalanced deployment and therefore increase the hardware cost. This paper presents an efficient obstacle-free robot deployment algorithm, called OFRD which involves the design of node placement policy, snake-like movement policy, and obstacle handling rules. By applying the proposed OFRD, the robot rapidly deploys near-minimal number of sensor nodes to achieve full sensing coverage even though there exist unpredicted obstacles. Performance results reveal that OFRD outperforms the existing robot deployment mechanism in terms of power conservation and obstacle resistance, and, therefore achieves a better deployment performance.[[incitationindex]]Y[[conferencetype]]國際[[conferencedate]]20070311~20070315[[conferencelocation]]Kowloon, Hong Kon