• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.21-30
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• 2020

In this paper, we predicted the propagation loss for the air-to-ground (A2G) channel between the ground control system and the unmanned aerial vehicle (UAV) using the prediction model for the aircraft recommended by the International Telecommunication Union (ITU). We analyzed the network coverage of the aerial relay system based on the medium altitude UAVs by expanding it into the air-to-air (A2A) channel. Climate and geographic factors in Korea were used to predict propagation loss due to atmospheres. We used the measured data published by the Telecommunication Technology Association (TTA) for regional rainfall-rate and effective earth radius factors to increase accuracy. In addition, the aerial relay communication system used the key parameter of the common data link (CDL) system developed in Korea recently. Prediction results show that the network coverage of the aerial relay system broadens at higher altitude.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.41-49
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• 2009

A crucial issue in deploying wireless sensor networks is to perform a sensing task in an area of interest in an energy-efficient manner since sensor nodes have limited energy Power. The most practical solution to solve this problem is to use a node wake-up scheduling protocol that some sensor nodes stay active to provide sensing service, while the others are inactive for conserving their energy In this paper, we present a simple wake-up scheduling protocol, which can maintain sensing coverage required by applications and yet increase network lifetime by turning off some redundant nodes. In order to do this, we use the concept of a weighted average distance. A node decides whether it is active or inactive based on the weighted average distance. The proposed protocol allows sensor nodes to sleep dynamically while satisfying the required sensing coverage.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.91-98
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• 2022

Unmanned aircraft system traffic management (UTM) service for the safe operation of unmanned aerial vehicles (UAV) such as drones using commercial communication networks such as long-term evolution (LTE) and 5G in low-altitude areas of 150m or less is being studied in several countries. In this paper, whether it is possible to secure three-dimensional (3D) coverage for UTM service using the existing LTE cellular network for terrestrial usersis analyzed through simulations. The practicality in the real environment is confirmed by performing performance analysis in the actual topographical environment and the LTE base station layouts in Korea. According to the analysis results, as the altitude increases, the number of line-of-sight (LOS) interference base stations increases, resulting in a worse signal to interference plus noise ratio (SINR), but coverage is secured except for the limited areas within 150m. was confirmed to be possible. In addition, it is confirmed that a significant proportion of outage areas could be reduced by placing a small number of additional base stations for the outage area.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.3
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• pp.75-85
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• 2012

In general, cellular network is deployed as distributed network architecture, so network equipment is spread out all over the coverage area. This case causes high cost. Recently, centralized network architecture has been deployable at cellular network since base station was able to be virtualized due to advance in computing power. The centralized network architecture in cellular network adjusts its cell radius dynamically and minimizes power consumption of the network. This paper introduces a new centralized deployment way of cellular network using SDR and cloud computing technology. Then, advantage and feasibility of the new network will be reviewed by implementing this novel network.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.7-9
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• 2006

본 논문에서는 정적인(static) 무선 애드 혹 네트워크상에서 에너지 효율적으로 broadcast하는 문제에 대한 새로운 "Broadcast by iterative Coverage sequence Adjustment with Hitch-hiking (BCAH)" 알고리즘을 제안한다. BCAH는 에너지 효율적인 broadcast알고리즘 중 가장 대표적인 Broadcast Incremental Power(BIP)와 같은 시간 복잡도를 가지면서 BIP에 비해 적은 에너지를 소모해 broadcast를 수행한다. 또한 BCAH는 각 노드의 인접한 노드들의 정보만을 이용해 동작하기 때문에 노드들의 이동성을 고려한 동적인 네트워크에 좋은 확장성을 가진다.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.349-357
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• 2005

In this paper, a new clustering algorithm using the Guaranteed Minimum Coverage (GMC) is proposed. In the new protocol, an appropriate distribution of clusterheads is accomplished by guaranteeing a stochastic coverage at each clusterhead(CH)s. Using this protocol, the communication cost from clusterheads to their member nodes and the load variance in each clusterheads are reduced. Therefore, the network lifetime can be extended and the fair energy consumption for all CHs can be achieved

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1718-1720
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• 2010

저 전력 무선 센서 네트워크와 마이크로 센서를 결합하여 환경이나 상황을 인지하고 모니터링을 통해 수집된 정보를 사람에게 전하는 WSN(Wireless Sensor Network) 기술에 대한 많은 연구가 진행되고 있다. 본 논문은 바이너리 모델을 사용하여 단순 탐지 확률을 표현하는 기존 시뮬레이터들의 Coverage 표현의 한계를 극복하기 위해 Heat-map을 이용한 시뮬레이터를 개발했다. 이 시스템은 기존 바이너리 모델을 확장하고, GIS를 사용하여 지형정보를 함께 가시화함으로써 서비스 지형에 대한 센서 네트워크 구성뿐만 아니라 수명예측 메커니즘을 이용한 에너지 소모에 따른 노드의 수명을 가시화 한다.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.859-866
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• 2001

Recently, fault injection techniques are used for evaluation of the fault coverage properties of safety-critical systems. This paper describes the TCN Fault Injector(TFI) implemented for TCN safety analysis. The implemented TFI injects network level faults to Intelligent MVB Controller that is designed for the Korean High Speed Train. With TFI, it can be verified whether the MVB controller meets TCN specification and its safety requirements.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.296-297
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• 2006

This paper presents a method to optimize train radio communication network for train control (CBTC) or multimedia services. To determine the optimized distance between wayside radio stations in a radio communication network constructed along railway, radio frequency allocation and hand-over capability is studied in terms of radio communication cell coverage and roaming feasibility.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1568-1569
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• 2005

This paper presents a method to optimize train radio communication network for train control(CBTC) or multimedia services. To determine the optimized distance between wayside radio stations in a radio communication network constructed along railway, radio frequency allocation and hand-over capability is studied in terms of radio communication cell coverage and roaming feasibility.