Browsing by Author "Wu, Chao-Nan"

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A Backbone-Aware Topology Formation (BATF) Scheme for ZigBee Wireless Sensor Networks
(2013-01-01)
Huang, Kuei-Li
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Yen, Li-Hsing
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Wang, Jui-Tang
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Wu, Chao-Nan
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Tseng, Chien-Chao
In a tree-structured ZigBee wireless sensor network, nodes close to the root of the tree (i.e., hot-spot nodes) may exhaust their power earlier than those distant from the root due to heavy loads on packet forwarding. This hot-spot problem is inherent in tree-structured networks and may demand extra energy to recover from failures of hot-spot nodes. In this paper, the backbone-aware topology formation (BATF) scheme is proposed to alleviate the hot-spot problem. BATF utilizes power-rich nodes to form a backbone tree that does not suffer from the hot-spot problem. Each power-rich node independently initiates a ZigBee tree network that attracts associations from ZigBee-compliant devices in order to distribute packet-forwarding loads over a larger set of nodes. Issues of BATF such as the partition of address space and ZigBee-compliant routing are discussed in detail. Simulation results confirm that BATF does alleviate the hot-spot problem as it improves network lifetime as well as data collection capability. Comparisons with native ZigBee protocols show that the improvement comes from our protocol design rather than simply introducing power-rich nodes.
POWER-EFFICIENT BACKBONE-ORIENTED WIRELESS SENSOR NETWORK, METHOD FOR CONSTRUCTING THE SAME AND METHOD FOR REPAIRING THE SAME
(2011-03-03)
Huang, Kuei-Li
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Wu, Chao-Nan
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Wang, Jui-Tang
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Tseng, Chien-Chao
The present invention discloses a power-efficient backbone-oriented wireless sensor network, a method for constructing the same and a method for repairing the same, wherein energy-rich nodes are used to form backbones linking to a server, and wherein regular nodes having limited energy storage link to the backbones. When one energy-rich node malfunctions, the energy-rich node, which is posterior to the malfunctioning energy-rich node, searches for and links to a linkable neighboring energy-rich node on the backbone. If there is none linkable neighboring energy-rich node, the regular nodes are used to form a temporary tunnel until the malfunctioning energy-rich node has been repaired. The present invention can relieve the influence of hot spots, increase the robustness of the wireless sensor network, and prolong the service life of the wireless sensor network.
ROUTING METHOD AND ROUTING PATH RECOVERY MECHANISM IN WIRELESS SENSOR NETWORK ENVIRONMENT
(2010-10-14)
LAI, Jun-Yu
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Huang, Kuei-Li
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Wang, Jui-Tang
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Tseng, Chien-Chao
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Wu, Chao-Nan
The present invention discloses an asymmetric routing method and routing path recovery mechanism. The wireless sensor network environment includes at least a management unit, at least a gateway, and mobile nodes. When joining, each mobile node obtains an unique ID code and, additionally, a depth as the gradient to the management unit. Accordingly, a mobile node sends an uplink packet via a nearby node with lower depth to the management unit; while the management unit transmits a downlink packet to a mobile node by utilizing the source route method. When the parent node of a mobile node is damaged or moves to another position or said mobile node with its sub-tree descendants changes their position together, the uplink routing path is recovered via selecting a nearby node of the sub-tree as relay node and the downlink routing path is recovered via sending a control message to the management unit.