• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.321-322
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• 2008

CSS(Chirp Spread Spectrum) technology adopt SDS-TWR algorithms of TOA(Time of Arrival) using velocity of specific medium and ToF(Time of Flight) to measure a distance, but this method always has a regular error on distance regardless of a real distance, as a result, in far distance, it decrease a error on distance relatively, but in near distance, it increase a error on distance relatively. in this paper, we propose and test new method measuring a distance more precisely in near distance using CSS and RSSI

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.174-176
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• 2006

Sensor network supports data delivery from Physical world to cyber space. Sensors get physical events then wireless network transfers sensor data to service server. We use sensor network technology to light control system for intelligent building. In ubiquitous computing environment. wireless sensor network is basic tool for intelligent service. In this paper, we propose intelligent building light control system based on wireless sensor network. It is implemented using previous light control product, can be adopted to present building light system.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.131-139
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• 2007

The recent advance in wireless network technologies has enabled the streaming media service on the mobile devices such as PDAs and cellular phones. Since the wireless network has low bandwidth channels and mobile devices are actually composed of limited hardware specifications, the transcoding technology is needed to adapt streaming media to given mobile devices. Futhermore owing to the diversity of bandwidth in the wireless network by reason of mobile users' movements and environments, it is difficult to provide stable QoS. In this paper, the autonomic multimedia transcoding system is proposed in order for users to provide network adaptive QoS. Our proposed system is based on the estimation of available bandwidth in wireless network for seamless multimedia streaming service. The proposed system is designed and implemented for various mobile clients. In experiments, we evaluate its seamless multimedia streaming and the adaptation transcoding bit rate according to the changes of bandwidth in wireless network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.998-1013
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• 2013

Wireless wearable sensor networks have emerged as a promising technique for human motion tracking due to the flexibility and scalability. In such system several wireless sensor nodes being attached to human limb construct a wearable sensor network, where each sensor node including MEMS sensors (such as 3-axis accelerometer, 3-axis magnetometer and 3-axis gyroscope) monitors the limb orientation and transmits these information to the base station for reconstruction via low-power wireless communication technique. Due to the energy constraint, the high fidelity requirement for real time rendering of human motion and tiny operating system embedded in each sensor node adds more challenges for the system implementation. In this paper, we discuss such challenges and experiences in detail during the implementation of such system with wireless wearable sensor network which includes COTS wireless sensor nodes (Imote 2) and uses TinyOS 1.x in each sensor node. Since our system uses the COTS sensor nodes and popular tiny operating system, it might be helpful for further exploration in such field.

• Electronics and Telecommunications Trends
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• v.38 no.3
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• pp.20-28
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• 2023

Wireless communication technology has mainly been used to fulfill the demands of industrial sites at which performance is not a critical concern. However, ongoing discussions and efforts are now focused on securing core wireless communication technologies to enable the transformation or expansion of wired industrial IoT (Internet of Things) network technology into a flexible and dynamic smart manufacturing system. This paper provides an overview of current wireless industrial IoT network technology and the recent wireless time-sensitive networking technology. It outlines the challenging level of reliability required for wireless communication technology to coexist with or replace its wired counterpart in future smart manufacturing systems. Additionally, we introduce ultra-reliable time deterministic network as the core technology of wireless industrial communications and focus on its reliability and delay characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1933-1941
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• 2016

This paper compares the performance of wireless communication technologies to replace the wired networks by wireless networks on avionics intra-communication. Due to the drawbacks of wired network, such as complexity, weight, maintenance cost and scalability, it leads to the high data rate and network traffic demands of avionics systems. Therefore, in WAIC(Wireless Avionics Intra-Communications) system suggested by ITU(International Telecommunication Union), based on environment of avionics system and requirements of a wired network, wireless network structures are defined to solve the problems of wired networks. In this paper, we consider features, advantages and disadvantages of wireless communication technologies which can be used for wireless avionics network, and we propose suitable wireless communication technology candidates for wireless avionics networks in WAIC environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1077-1093
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• 2013

This paper proposes a new network coordinator node design to select the most suitable wireless technology for WBANs by using fuzzy logic. Its goal is to select a wireless communication technology available considering the user/application requirements and network conditions. A WBAN is composed of a set of sensors placed in, on, or around human body, which monitors the human body functions and the surrounding environment. In an effort to send sensor readings from human body to medical center or a station, a WBAN needs to stay connected to a local or a wide area network by using various wireless communication technologies. Nowadays, several wireless networking technologies may be utilized in WLANs and/or WANs each of which is capable of sending WBAN sensor readings to the desired destination. Therefore, choosing the best serving wireless communications technology has critical importance to provide quality of service support and cost efficient connections for WBAN users. In this work, we have developed, modeled, and simulated some networking scenarios utilizing our fuzzy logic-based NCN by using OPNET and MATLAB. Besides, we have compared our proposed fuzzy logic based algorithm with widely used RSSI-based AP selection algorithm. The results obtained from the simulations show that the proposed approach provides appropriate outcomes for both the WBAN users and the overall network.

• ETRI Journal
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• v.28 no.1
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• pp.91-94
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• 2006

Impulse radio (IR) is a competitive candidate for ultra-wideband (UWB) systems. In this letter, we evaluated the coexistence of an IR-UWB system based on an orthogonal sinusoidal correlation receiver (OSCR) with an IEEE 802.11a WLAN through a detailed simulation. The coexistence performance of the two systems is characterized in terms of the receiver's bit-error rates. Then, some approaches to interference mitigation are discussed.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.117-119
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• 2006

BACnet(Building Automation and Control networks) is a standard data communication protocol designed specifically for building automation and control systems. BACnet provides five options for datalink layer protocols and these five datalink layer options can be applied with various transmission media. Recently wireless technology prevails in automation area. ZigBee is a standard protocol based on IEEE 802.15.4 for low-speed wireless communication network. In this study, we propose a BACnet/ZigBee model that uses ZigBee wireless technology in a BACnet communication network system as a wireless datalink layer protocol. We also applied this model to a lighting control system to evaluate the feasibility of proposed technology. The technology proposed in this paper can extend the application of BACnet not only for building automation but also for home automation by taking the advantages of ZigBee wireless communication technology in BACnet communication network systems.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.253-259
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• 2010

Wireless mesh network is flexible network like Ad hoc network or bluetooth together based on base station. But, wireless mesh network shows high packet loss and when TCP was created, however as it was design based on wired link, wireless link made more transmission error than wired link. It is existent problem of TCP congestion control algorithm that TCP unfairness and congestion collapse over wireless mesh network. When TCP operation occurs with the packet loss where is not the congestion loss, it brings the performance degradation which is serious. In this paper, in order to improve efficient TCP congestion control algorithm in wireless mesh network, we proposed that TCP can adaptively regulate the congestion window in wireless link.