• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.848-850
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• 2014

Mobile Ad hoc Networks(MANET) is consist of node that has mobility, MANET build cluster formation for using energy efficient. In existing LEACH algorithm elect cluster head node in coverage area by distribution function. However, when the cluster head node, that elected by distribution function, is divided coverage area unevenly, the network can't consumption energy efficiency. To solve this problem, we proposed CSWC(Coverage Scheduling Weight-value Control) algorithm. When the coverage area is divided nonchalance, proposed algorithm increased number of hops, that determines coverage area, for balance coverage area. As the result proposed algorithm is set balance coverage area, the network consumption energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.323-325
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• 2014

The consensus algorithm has a faster convergence speed as the number of cooperating neighbors increases, but the information sharing delay in the wireless network increases due to access collisions as the number of cooperating neighbors increases. Therefore, there exists a tradeoff between these two performances according to node's coverage. In this paper, we present a method of coverage control that minimizes consensus time according to network scale.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.485-488
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• 2011

무선 센서 네트워크에는 한정된 배터리 자원과 네트워크의 라이프타임(lifetime)으로 인해 멀티레벨 커버리지 문제가 이슈가 되어 왔다. 하지만, 대부분의 연구에서는 멀티레벨 커버리지 문제를 해결할 때 센싱 범위는 고정적이며 변경할 수 없음을 가정하고 있으며, 이로 인해 센싱 범위와 커버리지 범위와의 관계에 대해서 고려하고 않고 있다. 본 연구에서는 센싱 범위와 커버리지 범위와의 관계를 이용하여 유동 센싱 범위(DSR, Dynamic Sensing Range) 배치에 대하여 연구하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.116-119
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• 2015

In this paper we propose an algorithm for environment monitoring using multiple mobile sensor (MS) nodes. Our focus is on maximizing sensing coverage of a group of MS nodes for monitoring a phenomenon in an unknown and open area over time. In the proposed algorithm, MS nodes are iteratively relocated to new positions at which a higher sensing coverage can be obtained. We formulated an integer linear programming (ILP) optimization problem to find the optimal positions for MS nodes with the objective of coverage maximization. The performance evaluation was performed to confirm that the proposed algorithm can enable MS nodes to relocate to high interest positions, and obtain a maximum sensing coverage.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.707-711
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• 2003

상호접속원가는 통신망의 가입자 액세스 비용 인정여부에 따라 크게 달라지게 된다. 이동망은 유선망과 달리 가입자에게 할당된 직접적인 가입자 선로가 없는 대신 서비스 지역내 어디에서든지 호를 접속할 수 있는 능력 즉 커버리지를 제공하고 있으며, 이 커버리지 비용은 유선망의 가입자 선로비용에 해당하는 것으로 간주할 수 있다. 2002년 12월 개정 전기통신설비의 상호접속기준 22조의4의 장기증분비용 방식을 적용함에 있어 유선망은 각국에서 선행연구가 진행되어 왔고 실제 적용사례도 많기 때문에 비교적 사업자간 합의점을 찾기 용이한 측면이 있으나 이동망의 경우 선행연구가 부족하기 때문에 원가범위를 둘러싼 당사자간 논란의 여지가 많은 실정이다. 본 연구에서는 국내 이동시장환경을 분석하여 합리적인 이동망의 가입자 액세스 구간인 커버리지 정의와 범주를 살펴보고, 이동망 커버리지 비용 처리 방안을 살펴보고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.140-146
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• 2018

Recently, VLC(Visible Light Communication) fusing with LED(Light Emitting Diode) used in indoor lighting and wireless communication technology has attracted attention. However, the VLC can communicate only within the coverage to measure the optical signal and the communication disconnection phenomenon is occur in the NLoS(Non-Line-of-Sight) area. In this paper, we propose VLC relay module to extend the coverage of VLC and improve the communication disconnection phenomenon in NLoS area. The proposed VLC relay module transmits the packet received from the transmitter to the VLC relay module and receiver. The experiment was carried out by installing one VLC transmitter and three VLC relay modules, communication coverage expansion and the improvement of communication disconnection phenomenon in the NLoS were confirmed by the increase of the VLC relay module. Also, we confirmed that the optical signal measurement performance is improved 2.4 times by using the dual sampling method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.556-560
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• 2013

Recently, solutions to accommodate explosively growing mobile data traffic have attracted intensive attentions since the emergence of high-performance smartphones. Spectrum which can be exploited for mobile communications is very limited. Thus, femto cell is considered as an alternative because it can efficiently offload mobile data traffic from macro cells without using additional spectrum. In this paper, we mathematically analyzed the coverage of femto cell when it is deployed in an area where there exists signals from existing macro base stations. Our numerical results indicate that the coverage of femto cell increases as the total power of femto cell increases or the ratio of power allocated to pilot channel increases. However, it is also shown that the coverage of femto cell is very limited despite its high power when interference signals from macro base stations are strong.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.1
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• pp.18-25
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• 2013

In this paper, we propose a self-optimization scheme for indoor femtocell coverage in heterogeneous networks. If the femtocell coverage is larger than indoor area, neighbor cell users passing by the outer area of the femtocell coverage may request an unnecessary handover which incurs wasteful signaling overhead. On the other hand, if the coverage is smaller than the indoor area, some of indoor users might not be connected to the indoor femtocell. Therefore, we propose the method by which the femtocell coverage attains the exact indoor area employing self-organized scheme. Autonomous self TX power adjustment of the femtocell is possible because the proposed method utilizes handover request events and membership information of users that can be obtained by the femtocell itself. We show that the TX power obtained by the proposed algorithm converges to the optimal TX power that can be obtained analytically to attain the indoor coverage area.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.101-103
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• 2019

초고속해상무선통신망(LTE-Maritime)은 연안으로부터 100km 까지 전국 3해안(동 서 남해)에 LTE(Long Term Evolution) 통신 체계를 구축하여 항해 중인 선박(어선, 소형선박, 상선 등)을 대상으로 바다에서도 LTE급의 데이터 통신이 가능한 해상 e-Navigation 서비스 제공을 목표로 한다. 본 논문은 초고속해상무선통신망의 커버리지 및 통신서비스 품질검증 기준이 되는 연안으로부터의 통신서비스 제공 거리, 전송 속도, 전송성공률 등에 대해 검토해 보고, 각 품질 지표를 검증할 수 있는 시험항목 설정, 시험 환경 구성, 시험 방법 및 품질 결과 분석 방안에 대해 논의해보고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1026-1037
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• 2016

3rd Generation Partnership Project (3GPP) is the progressing standardization of the narrowband IoT (NB-IoT) system to support massive devices for the Internet of Things (IoT) services. The NB-IoT system uses a coverage class technique to increase the performance of the NB-IoT system while serving massive devices in very wide coverage area. A moving device can change the coverage class according to the distance or the channel state between the base station and the moving device. However, in the conventional NB-IoT standard, the performance of the NB-IoT system degrades because the coverage class is changed based on the fixed criterion. This paper proposes the coverage class adaptation schemes to increase the performance of the NB-IoT system by dynamically change the coverage class according to the location or the channel state of the device. Simulation results show that the proposed coverage class adaptation scheme decreases both the signaling overhead and the PDCCH decoding error rate in comparison with the conventional coverage class adaptation scheme in the 3GPP standard.