• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.525-530
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• 2008

There are a few core technologies to enable high-performance $4^{th}$ generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate transmission such as Mobile WiMAX and WLAN. Efficient decrease of inter-carrier interference (ISI) and inter-carrier interference (ICI) are the reasons for why OFDM is suitable for high-performance transmission, 4G mobile communication. In this paper, we mainly focus on two of objects, combination between MIMO and OFDM, and OFDM channel simulator using Ray-tracing algorithm. The results of this paper can be used implementation of a Wireless Software Platform for 4G Mobile Communication Systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5449-5464
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• 2018

Recent works have validated the possibility of reducing the energy consumption in wireless heterogeneous networks, achieved by switching on/off some base stations (BSs) dynamically. In this paper, to realize energy conservation, the discrete time Markov Decision Process (DTMDP) is developed to match up the BS switching operations with the traffic load variations. Then, an asynchronous decision-making algorithm, which is based on the Bellman equation and the on/off priorities of the BSs, is firstly put forward and proved to be optimal in this paper. Through reducing the state and action space during one decision, the proposed asynchronous algorithm can avoid the "curse of dimensionality" occurred in DTMDP frequently. Finally, numerical simulations are conducted to validate the effectiveness and advantages of the proposed asynchronous on/off strategies.

• 정보처리학회논문지A
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• 제14A권4호
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• pp.197-202
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• 2007

본 논문에서는 OpenGL-ES 기반의 모바일 3D 블루투스 게임 엔진을 설계 및 구현하였다. 기존 모바일 3D 네트워크 게임에서는 Wap(Wireless Application Protocol)과 VM 방식(Network)을 이용한 무선인터넷 게임이 주류를 이루고 있다. 그러나, 이들 모바일 네트워크 게임의 단점으로 지적되는 무선 네트워크 접속에 따른 지나친 통신 요금의 부담으로 인해 VM 형태를 기반으로 하는 다운로드형 게임 즉, 단독형 게임이 인기를 끌고 있다. 본 논문에서는 이러한 모바일 네트워크 게임의 단점을 해결하기 위해 모바일 3D 표준(C언어 기반)인 OpenGL-ES로 근거리에 있는 사람들이 무선 인터넷에 접속하지 않고, 모바일 3D 네트워크 게임을 즐길수 있는 모바일 3D 블루투스 게임 엔진을 제작하며, 다수의 블루투스 단말기 상에서 패킷 데이터를 전송할 때, 블루투스 처리 속도를 향상시키는 스케줄링(Scheduling) 방법을 제시한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.249-252
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• 2001

This paper focuses on the consideration of not only QoS parameters in wired network, but also QoS parameters in wireless network that supported for the Efficient QoS in the Al1 Service Levels. So, We supposed the "Efficient QoS Model" that guaranteed the QoS parameters "Loss Profile" , "Service Degradation" , "Latency and Jittering" , "Mobility of Mobile User" , "Probability of seamless communication" in wired-wireless networks. And the Method of Efficient QoS support that we supposed consists of "Multicast Routing-RSVP Protocol architecture based on Mobile IP" and "Protocols internetworking model ".

• 한국전자통신학회논문지
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• 제10권2호
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• pp.219-226
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• 2015

대표적인 4세대 이동통신 시스템으로서 LTE는 과거 이동통신 시스템에 비하여 훨씬 더 높은 전송 속도를 제공한다. 그러나 무선 환경의 특성 상 LTE가 제공하는 전송 속도는 무선 채널의 상태에 따라서 큰 영향을 받을 수 있다. LTE 시스템의 무선 접속을 통해서 제공되는 대부분의 서비스에 대한 사용자의 만족도는 전송속도에 일차적인 영향을 받게 된다. 따라서 본 논문에서는 무선 채널의 상태를 대표하는 다양한 품질 지표를 선정하고 이들에 대한 실체 측정을 실시하여 각 품질 지표의 변화에 대한 LTE 시스템의 전송 속도의 변화를 관찰하였다. 그 결과 채널의 상태가 나빠질수록 신호의 세기가 아닌 신호의 품질이 LTE 시스템이 제공하는 전송 속도에 밀접한 영향을 미친다는 사실을 알 수 있었다.

• 전자통신동향분석
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• 제34권6호
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• pp.61-70
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• 2019

Recently, research and development for next-generation mobile communication and short-range wireless communication has begun worldwide along with the provision of commercial services of 5G mobile communication technology. In response to this trend, the THz band has attracted considerable attention as a frequency band for transmitting 100 Gbps of large-capacity wireless data. For communication in the THz band, research and development of approaches based on photonics and electronics is being actively performed; the configurations, characteristics, and performances of these two methods for THz transmission have been seriously examined. Among them, we reviewed the technical issues in implementing THz wireless transmission technology using photonics technology. We also introduced the Electronic and Telecommunications Research Institute's (ETRI) development of photonics-based THz short-range transmission technology starting from 2019 and including some initial results. In the near future, 100 Gbps high-capacity wireless data transmission technology utilizing photonics technology is expected to be commercially available and applied to various applications, such as 3D hologram transmission, uncompressed large capacity medical data transmission, and multiple augmented reality/virtual reality (AR/VR).

• 한국산업융합학회 논문집
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• 제4권4호
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• pp.441-450
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• 2001

This dissertation deal with over-all wireless communication technology. And introduce wireless communication technology analytically that it use for Home-LAN communication technology (HomeRF, Bluetooth, IEEE 802.11, HIPERLAN, etc). Home-LAN communications issue by the terminal field of the latest high-speed network construction. This technologies possesses characteristics and significances as the representative technology using in Home-LAN communication technology. Also, the method of application is conditional on individually. Wireless LAN put Home-LAN communications to practical use. Bluetooth have practical use for an individual mobile communications with internet. HomeRF have a vision that the construction of wireless system in house purely. Therefore, this dissertation investigates merits and demerits between those technologies. And then leads the most compatible technology for application of Home-LAN. Finally, this thesis have a view of the development course hereafter.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1589-1592
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• 2003

Existing system management software solutions show limitations in time and space, as well as problems such as uncertain error messages, and also difficulty providing swift assistance or real time emergency support. Therefore, a wireless remote control system has been designed and implemented in this thesis, which is capable of managing and monitoring remote systems using mobile communication devices (Mobile Phone, PDA, Smart Phone, Webpad) for instantaneous control. The implemented real time wireless remote control system provides remote server management functions, error or event message (unctions, log record functions, authentication function via mobile devices.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.505-507
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• 2021

WSN (Wireless Sensor Network)에서 무선 데이터 전송 환경은 시스템 성능에 중요한 역할을 한다. 제안 이동 모델에서 이동 거리는 통신 성능에 많은 영향을 준다. 송수신 거리(d), 경로 손실(Path Loss), 수신 감도(Sensitivity), 비트 오류율(Bit Error Rate, BER), 신호 대 잡음 비율(SNR, Signal to Noise Ratio) 등은 무선 통신 시스템 설계할 때 고려사항들이다. 특히 MANET은 외부 기간망의 도움 없이 독립적으로 무선 단말끼리 만 서로 통신하며 이동하는 망의 형태이다. 본 논문은 WSN에서의 최적화된 전력사용 방안으로 이동 노드들의 이동 거리가 시스템 전체 에너지 효율에 미치는 영향에 관한 연구이다. 센서 노드들의 이동 가능 거리를 통신 가능 범위 안으로 제안함으로써 전체 네트워크의 수명을 연장하는 것을 본 연구의 목적으로 한다.

• ETRI Journal
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• 제41권3호
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• pp.326-336
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• 2019

A wireless power transfer technique can solve the power capacity problem in wireless rechargeable sensor networks (WRSNs). The charging strategy is a wide-spread research problem. In this paper, we propose a demand-based charging strategy (DBCS) for WRSNs. We improved the charging programming in four ways: clustering method, selecting to-be-charged nodes, charging path, and charging schedule. First, we proposed a multipoint improved K-means (MIKmeans) clustering algorithm to balance the energy consumption, which can group nodes based on location, residual energy, and historical contribution. Second, the dynamic selection algorithm for charging nodes (DSACN) was proposed to select on-demand charging nodes. Third, we designed simulated annealing based on performance and efficiency (SABPE) to optimize the charging path for a mobile charging vehicle (MCV) and reduce the charging time. Last, we proposed the DBCS to enhance the efficiency of the MCV. Simulations reveal that the strategy can achieve better performance in terms of reducing the charging path, thus increasing communication effectiveness and residual energy utility.