• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.83-90
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• 2015

This paper proposes a Tabu search algorithm to maximize the connectivity between the router nodes and the client nodes in wireless mesh networks. As the number of the router nodes and the client nodes in the networks increases, the amount of calculation for finding the solution would be too much increased. To obtain the optimal solution within a reasonable computation time for a high-density network, we propose a Tabu search algorithm to obtain the optimal solution for maximizing the connectivity. In order to make a search more efficient, we propose some efficient neighborhood generating operations of the Tabu search algorithm. We evaluate those performances through some experiments in terms of the maximum number of the connectivity and the execution time of the proposed algorithm. The comparison results show that the proposed algorithm outperforms other existing algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1670-1679
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• 2011

In the area of wireless sensor networks, sensor coverage and network connectivity problems are caused by a limited detection range and the communication distance of the nodes. To solve the coverage and connectivity problems, many studies are suggested, but most research is restricted to apply into the real environment because they didn't consider various environmental factors on wireless sensor network deployment. So in this paper, we propose a node deployment strategy considering environmental factors and the number of nodes in surveillance and reconnaissance sensor networks(SRSN). The proposed node deployment method divides the installation of the surveillance and reconnaissance sensor networks system into four steps such as identification of influences factors for node placement through IPB process, sensor node deployment based on sensing range, selection of monitoring site, and relay node deployment based on RF communication range. And it deploys the sensor nodes and relay nodes considered the features of the surveillance and reconnaissance sensor network system and environmental factors. The result of simulation indicates that the proposed node deployment method improves sensor coverage and network connectivity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4293-4304
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• 2014

In order to ensure the wireless connectivity and seamless service to mobile users, the next generation network system will be an integration of multiple wireless access networks. In a heterogeneous wireless access system, bandwidth allocation becomes crucial for load balancing to avoid network congestion and improve system utilization efficiency. In this article, we propose a new dynamic bandwidth allocation scheme for hierarchical wireless network systems. First, we derive a multi-objective decision criterion for each access point. Second, a bargaining strategy selection algorithm is developed for the dynamic bandwidth re-allocation. Based on the intervenient Stackelberg game model, the proposed scheme effectively formulates the competitive interaction situation between several access points. The system performance of proposed scheme is evaluated by using extensive simulations. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse network environments.

• ETRI Journal
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• v.35 no.4
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• pp.578-586
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• 2013

Using a sub-terahertz (sub-THz) wave generated using a photonics-based technology, a high-speed wireless link operating at up to 10 Gbps is designed and demonstrated for realization of seamless connectivity between wireless and wired networks. The sub-THz region is focused upon because of the possibility to obtain sufficient bandwidth without interference with the allocated RF bands. To verify the high-speed wireless link, such dynamic characteristics as the eye diagrams and bit error rate (BER) are measured at up to 10 Gbps for non-return-to-zero pseudorandom binary sequence $2^{31}-1$ data. From the measurement results, a receiver sensitivity of -23.5 dBm at $BER=10^{-12}$ is observed without any error corrections when the link distance between the transmitter and receiver is 3 m. Consequently, we hope that our design and experiment results will be helpful in implementing a high-speed wireless link using a sub-THz wave.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.281-287
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• 2007

The Bluetooth technology represents an attractive approach to enable short distance wireless connectivity. The Bluetooth standard operates at the 2.4 GHz ISM band and offers the advantage of establishing ad hoc networks, called piconet and scatternet. The spread of Bluetooth implementation in consumer products opens up a new short range wireless networking applications. Bluetooth MAC avoids packet collision within a piconet by simple time multiplexing. But lack of synchronization among independent neighboring piconets introduces packet overlapping within a time slot. In this paper, the wireless network throughput of Bluetooth packet transmission system applying the pure-ALOHA and slotted-ALOHA MAC is investigated according to the impact of channel environment. From the obtained results, the throughput of the Bluetooth MAC protocol shown to offer good performance in wireless channel, and the results are useful for the implementation of Bluetooth networks.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.720-729
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• 2011

The demand for wireless technology in home automation systems has recently been increasing due to several advantages such as installation cost reduction, easy placement, easy extension, aesthetic benefits, and mobile device connectivity. Among the many wireless technologies, ZigBee is one of the most useful for home automation; a wireless home networking system can be configured using ZigBee alone. Compatibility with conventional home networking systems that are based on wired media, however, is not supported. KNX is a mature protocol for wired media that is recognized as an international standard. This paper proposes a KNX-ZigBee gateway to interface between KNX and ZigBee systems and thereby enable integration of wired and wireless home automation systems.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.183-186
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• 2005

WUSB is a new technology which combines the speed and the security of wired USB with the easy use of wireless technology. In this paper, GUI for WUSB is designed and implemented to show the connectivity and contents of the WUSB devices. Also, the proposed GUI shows the log window while content transfers occur between the host and device. The proposed GUI can be used for various wireless technologies which provide wireless function with existing USB hosts and devices.

• ETRI Journal
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• v.30 no.2
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• pp.341-343
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• 2008

This letter presents an angular minimum spanning tree (AMST) algorithm for topology control in multi-hop wireless ad hoc networks. The AMST algorithm builds up an MST for every angular sector of a given degree around each node to determine optimal transmission power for connecting to its neighbors. We demonstrate that AMST preserves both local and network-wide connectivity. It also improves robustness to link failure and mitigates transmission power waste.

• Journal of Information Processing Systems
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• v.6 no.3
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• pp.295-306
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• 2010

Network lifetime is a critical issue in Wireless Sensor Networks (WSNs). In which, a large number of sensor nodes communicate together to perform a predetermined sensing task. In such networks, the network life time depends mainly on the lifetime of the sensor nodes constituting the network. Therefore, it is essential to balance the energy consumption among all sensor nodes to ensure the network connectivity. In this paper, we propose an energy-efficient data routing protocol for wireless sensor networks. Contrary to the protocol proposed in [6], that always selects the path with minimum hop count to the base station, our proposed routing protocol may choose a longer path that will provide better distribution of the energy consumption among the sensor nodes. Simulation results indicate clearly that compared to the routing protocol proposed in [6], our proposed protocol evenly distributes the energy consumption among the network nodes thus maximizing the network life time.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.47-52
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• 2006

In this paper, we suggested new network architecture to provide seamless service between the cellular system and new wireless broadband network such as IEEE 802.16e, called WiBro. The interworking technologies are very important issue because mobile operator should provide service connectivity between various wireless networks based on different access technologies. Moreover a change and modification on legacy network should be minimized for providing interworking with new wireless broad-band network. We implemented proposed interworking architecture between 3G cellular network and 802.16e network to provide seamless service including interworking unit in real test environment. Also, we performed performance evaluation in hybrid network environments.