• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.841-843
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• 2014

이동통신은 폭발적으로 증가하고 있는 무선데이터의 수요를 충족시키기 위해서 WCDMA, Wibro, LTE 등의 통신 방식으로 발전하고 있다. 이들 이동통신 방식을 수용하는 시스템들은 항시 전력을 사용하고 있고, 사용자에게 보다 편리하고 많은 서비스를 제공하기 위해서 한 기지국에 모두 설치되어 있는 경우가 일반적이다. 무선데이터의 수요는 시간, 장소 등에 따라서 유동적으로 변화한다. 만약 무선데이터의 수요에 따라서 현재 운용중인 이동통신 시스템들을 상황에 맞게 선택적으로 운용한다면 많은 전력을 절감할 수 있다. 본 논문에는 무선데이터의 수요에 따라서 운용하는 통신시스템에 전력공급을 제어하는 이동통신 인프라의 전력절감을 위한 부하관리 시스템의 설계와 구현에 관해서 기술한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.435-438
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• 2003

본 연구 논문에서는 기존의 무선통신을 이용한 정보전송의 단점인 통신비의 계속적 지출을 보완하고 MS카드의 정보를 무선으로 전송을 할 수 있는 시스템을 구현하였다. 테마파크나 주유소등 소규모의 네트워크로 충분히 소화가 가능한 지역의 경우 그 보안성이 우수하며 통신비용이 추가적으로 들지 않는 블루투스 프로토콜을 이용하여 효율적인 매장 관리를 가능케 하는 역할이 가능하다. 기존의 무선통신의 경우 지역적 통신망 내에서의 통신에도 추가적인 통신비용이 필요로 하는 무선 랜 프로토콜을 기반으로 네트워크를 구성하거나 보안이 취약한 RF 프로토콜을 이용한 네트워크를 구성하고 있다. 본 논문에서는 추가적인 비용이 전혀 들지 않는 지역적 통신망에 적합하면서도 주파수 호핑 방식으로 인한 보안성이 매우 좋은 블루투스 프로토콜을 통해 정보를 전송할 수 있도록 설계 하였다. 단말기는 저 전력, 고 성능의 RISC프로세서와 큰 화면의 LCD를 제공함으로써 점원용 휴대용 기기에 적합하도록 설계하였다. 본 논문에서 구현한 블루투스를 이용한 마그네틱 카드 정보 전송 시스템은 기존의 매장관리용 무선통신 시스템을 대체하여 추가적인 통신비용이 없이 지역적 통신망을 구축하고, 정보전송의 보안성을 높이며, 단말기의 저 전력 설계로 보다 오랜 시간 효율적으로 매장을 관리 할 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.911-923
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• 2014

Ad hoc cognitive radio wireless sensor networks allow secondary wireless sensor nodes to recognize spectrum opportunities and transmit data. Most existing protocols proposed for ad hoc cognitive radio wireless sensor networks require a dedicated common control channel. Allocating one channel just for control packet exchange is a waste of resources for channel-constrained networks. There are very few protocols that do not rely on a common control channel and that exchange channel-negotiation control packets during a pre-allocated time on the data channels. This, however, can require a substantial amount of time to access the channel when an incumbent is present on the channel, where the nodes are intended to negotiate for the data channel. This study examined channel access delay on cognitive radio wireless sensor networks that have no dedicated common control channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권2호
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• pp.209-218
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• 2009

In a wireless sensor network(WSN) each sensor node deals with numerous sensing data elements. For the sake of energy efficiency and network lifetime, sensing data must be handled effectively. A technique used for this is data aggregation. Sending/receiving data involves numerous steps such as MAC layer control packet handshakes and route path setup, and these steps consume energy. Because these steps are involved in all data communication, the total cost increases are related to the counts of data sent/received. Therefore, many studies have proposed sending combined data, which is known as data aggregation. Very effective methods to aggregate sensing data have been suggested, but there is no means of deciding how long the sensor node should wait for aggregation. This is a very important issue, because the wait time affects the total communication cost and data reliability. There are two types of data aggregation; the data counting method and the time waiting method. However, each has weaknesses in terms of the delay. A hybrid method can be adopted to alleviate these problems. But, it cannot provide an optimal point of aggregation. In this paper, we suggest a stochastic-based data aggregation scheme, which provides the cost(in terms of communication and delay) optimal aggregation point. We present numerical analysis and results.

• IEIE Transactions on Smart Processing and Computing
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• 제3권4호
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• pp.212-220
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• 2014

The current cellular communications are optimized for low mobility users, meaning that their performance is degraded at high speed. Therefore, passengers in a high-speed train experience very poor radio link quality due to the significantly large number of simultaneous handovers. In addition, wireless data traffic is expanding exponentially in trains, subways and buses due to the widespread use of smartphones and mobile devices. To solve the inherent problem of cellular communication networks and meet the growing traffic demand, this paper proposes the mobile hotspot network of a millimeter-wave communication system as a mobile wireless backhaul. This paper describes the physical layer design of uplink and downlink in the proposed system, and the performances of uplink and downlink are evaluated under Rician fading channel conditions. The implemented baseband prototype of the proposed millimeter-wave communication modem is presented. This system can provide a Gbps data rate service in high-speed trains carrying hundreds of wireless Internet users.

• International Journal of Internet, Broadcasting and Communication
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• 제12권3호
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• pp.32-38
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• 2020

The deployment of geographically distributed wireless sensors has greatly elevated the capability of monitoring structural health in social-overhead capital (SOC) public infrastructures. This paper deals with the utilization of a distributed mobility management (DMM) approach for the deployment of wireless sensing devices in a structural health monitoring system (SHM). Then, a wireless sensing mechanism utilizing low-energy adaptive clustering hierarchy (LEACH)-based clustering algorithm for smart sensors has been analyzed to support the seamless data transmission of structural health information which is essentially important to guarantee public safety. The clustering of smart sensors will be able to provide real-time monitoring of structural health and a filtering algorithm to boost the transmission of critical information over heterogeneous wireless and mobile networks.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.243-248
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• 2003

This paper is contents on that construct ultra high speed wireless communication cell backbone net of city using of wireless communication transceiver for millimeter wave band. A new type of 60GHz wave band wireless transceiver using NRD waveguide. This 60GHz transceiver has excellent signal's absorption characteristics of oxygen molecule than the other millimeter wave bands. We constructed service networks to cell interval within about 500m to 3Km laying stress on wireless backbone node using 60GHz transceivers, and did it so that city type wireless communication cell backbone networks of 155.52Mbps ATM(OC-3) may be possible. The possible use of wireless backbone networks technology in a rainy day and a clear day was evaluated at 1Km data link distance. We can measured bit error rate(BER). BER is $10^{-11}$ at 155.52Mbps ATM(OC-3) in a clear day and $10^{-6}$ in a heavy rain more than 35mm per time. Also, we constructed wireless cell backbone networks distance to use several 60GHz transceivers and investigated data transmission rate between main center and local center of long distance. In proposed wireless cell backbone networks, the data throughput was approximately 80Mbit/sec. Therefore, if use transceiver, it is possible that city type ultra high speed wireless communication cell backbone networks construction of 100Mbps, 155.52Mbps, 622Mbps, 1Gbps and 1.2Gbps degrees.

• 한국전자통신학회논문지
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• 제12권5호
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• pp.755-762
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• 2017

철도통신에서 데이터의 전송속도를 향상시키고 신뢰성 있는 데이터 전송을 위해 LTE기반 철도 무선통신시스템에 대한 연구가 진행되고 있다. 본 논문에서는 LTE기반의 철도 무선통신시스템의 테스트베드에 대해 소개한다. 테스트베드상에서 무선통신시스템을 이용하여 전계강도, 통신 도달거리, 통화설정시간, 핸드오버 성공률, 데이터 전송속도 등과 같은 기본적인 통신성능 측정결과에 대해 소개한다. 이 결과를 바탕으로 향후 시스템 상용화에 필요한 사항들에 대해 논의한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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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 information and communication convergence engineering
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• 제4권2호
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• pp.62-66
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• 2006

The objective of this thesis is to measure the limit of the real space where wireless Local Area Network (LAN) is used, and to apply this result as reference to set up a real Wireless LAN environment. The organized circumference was composed of Wireless LAN based on IEEE 802.11b of the American standard, and the examination is carried out on the campus. On the real condition of office environment and open space, the ratio of available distance to a signal at each distance was measured and this result was studied as data to embody wireless LAN on the campus. The measurement under an indoor environment was executed under circumstance having two walls and open space, however, was executed respectively under three circumstances: Where no obstacle, where one wall exists, and where two or more walls exist.