• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.101-110
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• 2009

The 6LoWPAN(IPv6 Low-power Wireless Personal Area Network) performs IPv6 header compression, TCP/UDP/IGMP header compression, packet fragmentation and re-assemble to transmit IPv6 packet over IEEE 802,15.4 MAC/PHY. However, from the point of view of security. It has the existing security threats issued by IP packet fragmenting and reassembling, and new security threats issued by 6LoWPAN packet fragmenting and reassembling would be introduced additionally. If fragmented packets are retransmitted by replay attacks frequently, sensor nodes will be confronted with the communication disruption. This paper analysis security threats introduced by 6LoWPAN fragmenting and reassembling, and proposes a re-transmission mechanism that could minimize re-transmission to be issued by replay attacks. Re-transmission procedure and fragmented packet structure based on the 6LoWPAN standard(RFC4944) are designed. We estimate also re-transmission delay of the proposed mechanism. The mechanism utilizes timestamp, nonce, and checksum to protect replay attacks. It could minimize reassemble buffer overflow, waste of computing resource, node rebooting etc., by removing packet fragmentation and reassemble unnecessary.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.18-23
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• 2008

This paper describes development of real-time condition monitoring system to observe state of a container crane in a port. To analyze the state of a crane, the strength and the direction of wind are measured with sensors along with the load resulted a crane at the moment. The measured signals are processed by especially developed conditioning board and converted into digital data. Measured data are analyzed to define the state of the crane at an indicator. For transmission of these data to the indicator, we implemented wireless sensor network based on IEEE 802.15.4 MAC(Media Access Control) protocol and Bluetooth network protocol. To extend the networking distance between the indicator and sensor nodes, the shortest path routing algorithm was applied for WSN(Wireless Sensor Network) networks. The indicator sends the state information of the crane to monitoring server through IEEE 802.11 b wireless LAN(Local Area Network). Monitoring server decides whether alarm should be issued or not. The performance of developed WSN and Bluetooth network were evaluated and analyzed in terms of communication delay and throughput.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.632-638
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• 2012

ZigBee network, based on PHY, MAC layer provides a specification for a suite of high level communication protocols using small, low-power digital radio based on an IEEE 802.15.4 standard. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area. Each wireless technology that makes it to market serves a special purpose or function. Zigbee provides short-range connectivity in what is called a personal-area network (PAN). Within ZigBee PAN coordinator as manages an entire ZigBee network, the short range of frequency band was only selected because the technology allows typically less than 100 kbp or ZigBee troubles in retransmission processing and delaying data tranmission works to create unproductive condition of work. This research was proposed the method, based on short range frequency of zigBee nodes enable to long range of remote data transmission with specific algorithm tools.

• Electronics and Telecommunications Trends
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• v.25 no.4
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• pp.27-37
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• 2010

최근 들어 무선 센서네트워크는 온/습도 관리와 같은 단순한 기능의 저전력 모니터링 서비스에서 시의성과 무선 전송의 신뢰성을 요구하는 산업 자동화 서비스 및 스마트 그리드와 같이 통신 거리를 확장한 옥외 서비스를 위한 기술로 서비스 영역을 넓혀가고 있다. 무선 센서네트워크 기술은 자원의 제약에 기인한 고유의 특성을 갖는다. 특히 전송 계층 기술은 이러한 제약 사항을 고려하여 설계되어야 하며, 상위 계층 기술의 성능은 전송기술에 대한 성능적 의존성을 가질 수 밖에 없다. 본 고에서는 최근 무선센서 네트워크 서비스 확대를 위한 시장의 요구사항을 반영하여 표준화가 진행되고 있는 시의성/신뢰성 향상을 위한 IEEE 802 WG15의 TG4e MAC 기술과 스마트 유틸리티 네트워크를 위한 TG4g SUN PHY 기술에 대한 표준화 활동을 중심으로 표준 기술 동향을 소개하고 이에 대한 표준 전략을 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1185-1192
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WPAN protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless WPAN protocol, a Grid-based WPAN networking technology is proposed and analyzed. The proposed Grid-based WPAN networking technology supports multi-path and fast path-setup functions for N-screen communications. The simulation results demonstrate that the proposed Grid-based WPAN networking technology outperforms the IEEE 802.15.4 based network in terms of N-screen transmission delay.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.96-102
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• 2011

There are many problems with the fire detection devices being used in currently, because it is difficult to find location of the source of fire and determine where devices are working or not. In this paper, we proposed fire detection and rescue system using wireless sensor network that can be real-time monitoring and determine safe exit. Fire detection and rescue system based on ubiquitous sensor network can know exactly source of fire and help determine rescue tactics using sensing data from wireless sensor nodes. Transmitted wirelessly in real-time thermal sensor and gas sensor information to analyze the GUI to monitor the status information output to the screen by use of a system implemented in everyday life, looked at the possibility.

• Journal of Information Processing Systems
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• v.13 no.6
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• pp.1602-1612
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• 2017

Since rapidly disseminating of Internet of Things (IoT) as the new communication paradigm, a number of studies for various applications is being carried out. Especially, interest in the smart medical system is rising. In the smart medical system, a number of medical devices are distributed in popular area such as station and medical center, and this high density of medical device distribution can cause serious performance degradation of communication, referred to as the coexistence problem. When coexistence problem occurs in smart medical system, reliable transmitting of patient's biological information may not be guaranteed and patient's life can be jeopardized. Therefore, coexistence problem in smart medical system should be resolved. In this paper, we propose a distributed coexistence mitigation scheme for IoT-based smart medical system which can dynamically avoid interference in coexistence situation and can guarantee reliable communication. To evaluate the performance of the proposed scheme, we perform extensive simulations by comparing with IEEE 802.15.4 MAC protocol which is a traditional low-power communication technology.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.133-135
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• 2006

최근 유비쿼터스 컴퓨팅 시대에 가까워지면서, 다양한 형태의 소형센서를 무선네트웍으로 연결하여 일정 범위 내의 다양한 정보를 수집하여 이용할 수 있는 무선센서네트웍시스템에 대한 연구가 활발히 진행중이다. 현재 가장 널리 사용되고 있는 무선센서네트웍 아키텍처는 IEEE 802.15.4에 제안된 MAC과 ZigBee Alliance에서 개발된 ZigBee를 이용한 것이다. ZigBee에는 네트웍계층, 응용프레임웍 등 많은 기능과 규격이 포함되어 있으며, 그 중 응용프레임웍에는 각 센서장치들 간의 통신을 원활하게 하기 위하여 여러 가지 데이터 형이 정의되어 있다. ZigBee 응용프레임웍에 정의되어 있는 여러 데이터형 중 준정밀수형(semi-precision number type)은 수의 절대값이 작은 범위에서는 높은 해상도로 수를 표현할 수 있고 절대값이 큰 범위일수록 상대적으로 낮은 해상도로 수를 표현할 수 있어, 빛의 강도, 소리의 크기 등 그 크기를 표현함에 있어 절대값에 반비례하는 해상도로 표현하여도 무방한 경우 매우 유용하게 사용된다. 그러나 현재 ZigBee에서 정의한 준정밀수형은 높은 해상도로 표현되어야 하는 구간 중 특정 구간에서 해당 값을 표현할 수 없는 구간이 존재한다. 본 논문에서는 이와 같은 준정밀수의 특징과 문제점을 살펴보고, 이러한 문제를 해결할 수 있는 새로운 형식의 준정밀수형을 제안한다.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.339-342
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• 2005

In order to support ultrawide-band signal generation for low rate WPAN, several types of signal generation mechanisms are suggested such as Chaos, Impluse, and Chirp signals by the activity of IEEE 802.15.4a. The communication system applied chaos theory may have ultrawide-band characteristics with spread spectrum and immunity from multipath effect. In order to use the advantage of chaotic signal generation, we introduce the system implementation of communication and networking systems with the chaos UWB signal. This system may be composed of mainly three parts in hardware architecture : RF transmission with chaotic signal generation, signal receiver using amplifiers and filters, and 8051 & FPGA unit. The most difficult part is to implement the chaotic signal generator and build transceiver with it. The implementation of the system is devidced into two parts i.e. RF blocks and digital blocks with amplifiers, filters, ADC, 8051 processor, and FPGA. In this paper, we introduce the system block diagram for chaotic communications. Mainly the RF block is important for the system to have good performance based on the chaotic signal generator. And the main control board functions for controlling RF blocks, processing Tx and Rx data, and networking in MAC layer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.