Kun-Ying Hsieh

Power control based topology construction for the distributed wireless sensor networks

Wireless sensor network consists of large number of sensor nodes with limited battery power, which are randomly deployed over certain area for several applications. Due to limited energy resource of sensors, each of them should minimize the energy consumption to prolong the network lifetime. In this paper, a distributed algorithm for the multi-hop wireless sensor network is proposed to construct a novel energy efficient tree topology, without having location information of the nodes. Energy conservation of the nodes is accomplished by controlling transmission power of the nodes. Besides, maintenance of the network topology due to energy scarcity of the gateway nodes is also proposed in the protocol. Simulation results show that our distributed protocol can achieve energy conservation up to an optimum level similar to the centralized algorithm that we have considered and can extend the network lifetime as compared to other distributed algorithms without any power control.

Target tracking and boundary node selection algorithms of wireless sensor networks for internet services

Wireless sensor network (WSN) is an integral part of Internet of Things (IoT), in which sensors can be used to keep track with interesting targets under surveillance. Target tracking is one of the important research issues, where sensors are deployed in many applications such as campus security, surveillance, habitat and battle field monitoring. Information can be forwarded in an ad hoc multi-hop fashion via internet to monitor a specific region and can form a ubiquitous network for several internet services. In this paper, Sequential Boundary Node Selection (SBNS) and Distributed Boundary Node Selection (DBNS) algorithms are proposed to find out the boundary nodes of the wireless sensor network. Besides, a target tracking protocol is proposed to detect the entry and exit of the targets using those boundary nodes. Simulation results show that the selection of boundary nodes in our protocol is almost close to the optimal one and the time of selecting boundary nodes would not increase rapidly, with increase in the size of the deployed nodes.

Boundary Node Selection and Target Detection in Wireless Sensor Network

Recording information of the entry and exit of a target through the boundary of the deployed region is highly essential in wireless sensor network. In this paper, sequential boundary node selection (SBNS) and distributed boundary node selection (DBNS) algorithms are proposed to find out the boundary nodes of the wireless sensor network with or without presence of obstacles over the deployed region. Besides, a target detection protocol is proposed to detect the entry and exit of the single target using those boundary nodes. Simulation results show that the selection of boundary nodes in our protocol is almost close to the optimal one and time of selecting the boundary nodes would not increase rapidly with increase in size of the wireless sensor network.

Scalable continuous object detection and tracking in sensor networks

With the advancement of MEMS technologies, sensor networks have opened up broad application prospects. An important issue in wireless sensor networks is object detection and tracking, which typically involves two basic components, collaborative data processing and object location reporting. The former aims to have sensors collaborating in determining a concise digest of object location information, while the latter aims to transport a concise digest to sink in a timely manner. This issue has been intensively studied in individual objects, such as intruders. However, the characteristic of continuous objects has posed new challenges to this issue. Continuous objects can diffuse, increase in size, or split into multiple continuous objects, such as a noxious gas. In this paper, a scalable, topology-control-based approach for continuous object detection and tracking is proposed. Extensive simulations are conducted, which show a significant improvement over existing solutions.

Hole detection and boundary recognition in wireless sensor networks

Coverage holes may exist in wireless sensor networks (WSNs) due to presence of obstacles or invalid sensor nodes in the sensing field. Normally, the holes make the data routing failure when the nodes transmit their data back to the sink. In this paper, distributed protocols are developed to identify the boundary nodes surrounding the holes of the sensing filed in WSNs without using any location information. Experimental results demonstrate that our algorithm can precisely and correctly identify the boundary nodes even in sparsely sensors deployed regions. Besides, our algorithm can give better performance in terms of control packet overhead and simulation time as compared to previous work.

Design and implementation of a smart mobile robot

Most wireless sensor networks consist of a large number of static, low-power, short-lived, and unreliable sensors. In this paper, we considered sensor networks consisting of both static and mobile nodes. Integrating both types of devices enables new applications, such as nodes replacement, hole and partition recovery, and autonomous deployment and redeployment. We designed a smart mobile robot and implemented an application of nodes replacement to demonstrate its use, via our nodes replacement algorithm. In this algorithm, the mobile robots can navigate towards low-energy sensor nodes and replace them automatically, with new sensor nodes, having no location information. The navigation algorithm is based on received signal strength between the mobile robot and the communicating node. The experimental results confirm that the mobile robots successfully achieved their assigned tasks.

Routing with Hexagonal Virtual Coordinates in Wireless Sensor Networks

Using geographic routing, like GPSR, is efficient for ad hoc and wireless sensor networks, but it requires that nodes be aware of their physical positions. However, if there are holes in the network, routing across holes in GPSR will lead to a lot of overloaded nodes in the boundaries of the holes. In this paper, we propose a distributed protocol, named the hexagonal virtual coordinate (HVC), for constructing a virtual coordinate system. After the HVC is constructed, the nodes in the network will be aware of relative coordinates among the landmarks through the HVC chart. Based on the HVC chart, a source node can find an auxiliary routing path to indicate the direction of the journey from the source to the destination. Simulation results show that our protocol can support geographic routing efficiently.