• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.12-19
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• 2016

The monitoring system in railway is under study to forecast any derailment and accident by defect of train. Because the monitoring system is composed of wireless sensor network based on ZigBee-communication between inside and outside of train, the study for wireless channel analysis is required. Especially, if multipath delay profile exist in the channel, the equalizer and channel estimator can be required for preventing receiver performance degradation. Therefore, we analyzed the wireless channel in train environment using measured data and, proposed the channel estimation method through the characterisitic of chip code, under the consideration of the channel characteristics in train. To show the performance of proposed method, we demonstrate the performance by mean square error(MSE), computational complexity and bit error rate(BER).

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.8-13
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• 2016

A buoy is a float attached by chain to the seabed to mark channels in a harbor or underwater hazards and can be classified into two major types as autonomous buoys and fixed buoys. When there is high demand such as marking channels in a harbor, monitoring ecology of ocean and environmental monitoring of coastal areas, smart buoys are developed. The smart buoys have wireless network systems such as GPS, CDMA and ZigBee. Using the GPS techniques, location and environments of buoy can be monitored and traced. However, the GPS in fixed buoy systems has a high power consumption and cost. Using many buoys on low power ZigBee basis allows dramatic reduction of the overall power consumption. In this study, it is aimed at the design of the trackable protocol for a buoy system which has low data rate and low power consumption. The proposed protocol has advantages that it can detect abnormal movement and gather trackable information without any system changes. In the introduced protocol, additional 2 bits and join request messages are used for trackable buoy system. The behaviors of improved protocol is modeled into petri-net and proved a reachability.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.948-951
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• 2008

Ubiquitous sensor network (USN) based on ZigBee communication protocol has been used in various application fields, such as home-network, intelligent building and machine, logistics, environmental monitoring, military field, security field and etc. The ZigBee is targeted at radio-frequency application that require a low data rate, long battery life and secure network. Especially, the USN system can be applied efficiently to building-indoor where the complex geometry is adopted. In this study, all 90 points of railway cabin indoor were monitored for temperature and humidity using USN technology. All sensors were pre/post-calibrated and the temperature/humidity change were analyzed in a railway cabin in real-time. The results would be useful to develop the cabin heating, ventilating and air conditing (HVAC) system to meet all passengers' thermal comfort regardless of their seat position.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.27-28
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• 2007

In this paper, the Wireless Sensor Network (WSN) based on ZigBee technology was devised and developed. Wireless communication was applied to petrochemical domain, like other industries. And sensor network of IEEE 802.15.4 protocol stack diagram was described. Then, by analyzing the protocol, the software systems included the communication Protocol and point-to-point network were implemented with Freescale Semiconductor's product MC13192-SARD DSK board. After that, the performance of this design system was evaluated, and finally, by using PC Graphic User Interface (GUI) and IDE CW08 V3.1 programming tool, the real time communication data and the curve function were displayed.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.6
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• pp.47-54
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• 2008

In this paper, interference analysis has been performed between RF receiver and transmitters on each soldier for Multiple Integrated Laser Engagement System(MILES) which are following ZigBee standard. In order to obtain minimum transmit power without interference, 1% Packet Error Rates(PER) from 14 transmitters attached on a soldier to a receiver are measured with the scenarios for simple transmitting and receiving network configuration and for repeating network configuration. Based on this transmit power, the available distance for interference free among soldiers is simulated using Spectrum Engineering Advanced Monte Carlo Analysis Tool(SEAMCAT). Later scenario gives the benefit of 10dB lower transmit power, smaller and lighter power source, and better activity of trainee.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.116-120
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• 2008

The conventional channel selection method for a ZigBee communication network basically detects the energy values in all channels. In the ISM band, no license is required to use channels in this band, so there may exist various interference factors in this band. It is well known that WLAN is the major interference factor degrading the performance of ZigBee in the ISM band. In this paper, we propose an efficient channel selection algorithm which uses the pattern of WLAN channel uses as the a priori information. By using the proposed algorithm, we may save the time required to select channels for the ZigBee communications.

• Journal of Digital Contents Society
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• v.7 no.2
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• pp.103-108
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• 2006

Short-range wireless communication and networking technologies are becoming increasingly important in enabling useful mobile applications. for example, ZigBee technology is expected to provide low cost and low power connectivity for equipment that needs battery life as long as several months to several years. In addition, ZigBee can be implemented in mesh networks larger than is possible with Bluetooth. The main features of this ZigBee standard are network flexibility, low cost, very low power consumption, and low data rate in an adhoc self-organizing network among fixed, portable and moving devices. Home network/Home automation is one of the key market areas for Zigbee, with an example of a simple network This paper investigates the effect of short range wireless channel on the performance of Zigbee system and DSSS-BPSK signal transmission in AWGN, interference and Rician fading environments. And we investigate performance degradation due to interference and fading effects in short range wireless channel. In particular, the impacts of the fading and interference level on the bit error probability is shown in BER performance figures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.845-854
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• 2008

In this paper, we propose a clustering algorithm for efficient energy management of sensor network consisted of sensor nodes that have restricted energy to solve these problem. Proposed algorithm improves energy efficiency by controlling sensing power. And it has distinctive feature that is applied in various network environment. The performance evaluation result shows that the energy efficiency is improved by 5% in the case of all sensor node fixed and by $10{\sim}15%$ in the case of all sensor node moving. It is confirmed through experiment process that the proposed algorithm brings energy efficiency ratio improvement of $5{\sim}15%$ more than the existing algorithm. Proposed algorithm derived an upper bound on the energy efficiency for Ubiquitous Computing environment that have various network environment that is with ZigBee technology of IEEE 802.15.4 bases. Also, we can blow bring elevation for lifetime of sensor network greatly for lifetime of sensor node as is small. And we think that may expand practical use extent of a sensor network technology more in fast changed network environment.

• ETRI Journal
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• v.34 no.4
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• pp.625-628
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• 2012

In this letter, a novel method for localizing a user in a smart home environment is presented. We propose a two-level structure, in which the first level determines an occupant's location in the block level using RSSI in a ZigBee network, while the second level accurately estimates the occupant's location using a particle filter to handle the variations in the signal strength measurement. We devise an experimental setup with people performing significant tasks in the smart home. The results obtained from the testbed indicate that the proposed model leads to an improvement in the mean distance error.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.171-173
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• 2006

Because sensor networks use wireless communication, they are vulnerable to attacks which are more difficult launch in the wired domain. Many wired networks benefit from their inherent physical security properties. It is unlikely that an adversary will dig up the Internet backbone and splice into the line. However, wireless communications are difficult to protect; they are by nature a broadcast medium. In a broadcast medium, adversaries can easily eavesdrop on, intercept, inject, and alter transmitted data. In addition, adversaries are not restricted to using sensor network hardware. We have analyzed the IEEE 802.15.4, ZigBee specification which includes a number of security provisions and options. In this paper, we highlight places where USN security considerations and home network attack scenarios.