• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.634-639
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• 2008

In mobile communication networks, the main power consumption is due to the actual transmissions power. Therefore, power efficiency network structures have gained considerable importance in mobile multi-hop systems and networks in recent years. In this paper, the performance of mobile multi-hop wireless system with M-QAM signal and forward error control (FEC) technique are analyzed The FEC technique uses extra processing power related to encoding and decoding, it is need complex functions to be built into the communication node. The probability of receiving a correct bit and codeword for relaying a data frame over h hop relay station to the final station is evaluated as a function of channel parameter and number of hops, and the distance between the different station.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.101-108
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• 2017

A wireless image sensor node collecting image data for environmental monitoring or surveillance requires a large amount of energy to transmit the huge amount of video data. Even though solar energy can be used to overcome the energy constraint, since the collected energy is also limited, an efficient energy management scheme for transmitting a large amount of video data is needed. In this paper, we propose a method to reduce the number of blackout nodes and increase the amount of gathered data by selecting an appropriate video coding method according to the energy condition of the node in a solar-powered wireless video sensor network. This scheme allocates the amount of energy that can be used over time in order to seamlessly collect data regardless of night or day, and selects a high compression coding method when the allocated energy is large and a low compression coding when the quota is low. Thereby, it reduces the blackout of the relay node and increases the amount of data obtained at the sink node by allowing the data to be transmitted continuously. Also, if the energy is lower than operating normaly, the frame rate is adjusted to prevent the energy exhaustion of nodes. Simulation results show that the proposed scheme suppresses the energy exhaustion of the relay node and collects more data than other schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.911-918
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• 2008

In this paper, we propose new cell structures using multi-hop Relay Station(RS) based on IEEE802.16j in Narrow-Beam Trisector Cell (NBTC) and Wide-Beam Trisector Cell (WBTC), which are two methods for cell sectorization using 3-sector directional antennas. Then, we analyze our proposed structures compared with the existing system which does not use any RS about the numbers of optimized Base Station (BS) and multi-hop relay, the extended BS coverage, and the deployment cost according to the traffic density using optimization model. According to the results, we know the reduction of total deployment cost of the proposed systems and that WBTC is suitable when the traffic density is high and NBTC is suitable when the traffic density is low in our proposed multi-hop based NBTC and WBTC structures.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.64-68
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• 2010

In this paper, we studied the novel synchronization algorithm for cooperative communication system over fading. We research mainly on the decode-and-forward scheme. Also, we inserted spreading sequence in origin data frame to control efficiently data synchronization. In mobile station, inserted spreading sequence in data frame passed through the corelation process. We had decide the delay value of received data through result of correlation process. In simulation, We applied that channel gain of three node had different value in various fading environment. Finally we will be possible to control the received data synchronization using result of corelation value in each node between relay to mobile station and base station to mobile station. The results of this paper can be applicable to the cooperative systems.

• International Journal of Contents
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• v.1 no.1
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• pp.45-49
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• 2005

If the service provider provides mobile service with mobile switching centers that use different handoff message format, the soft-handoff between mobile switching centers is not available and the hard-handoff scheme is used instead. When this occurs, calls are often disconnected or there is an interruption of service. This can be very annoying to a mobile user. We propose the handoff subsystem of the ATM switch which provides the soft-handoff between wireless cells under the control of different MSCs. The proposed handoff subsystem transforms the handoff message format of the source MSC to that of the destination MSC. It also provides efficient routing scheme that distributes handoff packets to balance the traffic load.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.110-115
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• 2001

Today, effective utilization of sophisticated networks greatly influences the activities of a business, making performance evaluations of computer network systems a necessity, We have developed a special computer network simulator capable of automatically generating a model based on data accumulated by a network analyzer to guide the user in selecting ideal parameters. The simulator was developed to provide user-friendly analysis for engineers involved in the actual network design. This paper gives an overview of the simulator and describes an example application of evaluating a network design that anticipates the future increase in traffic for a company introducing voice over frame relay (VoFR) into a wide area network (WAW).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.379-386
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• 2004

The optimal seismic retrofitting of NPP(Nuclear Power Plant) cabinet structures that contained class 1 relays were studies in this paper. During earthquake event, the failure modes of relays are not appeared in form of structural failure, but are appeared in form of contact chatter of relay. Therefore, the retrofitting of cabinet has to be aimed to the reducing of the structural response, such as acceleration. In this study, the optimal characteristic values of dampers were searched by μ-GA (micro-Genetic Algorithm) scheme for several installation patterns. To keep accuracy and efficiency of analysis, the structural models of cabinet were considered as a frame structure. The responses of structure were obtained in form of acceleration response spectra derived from the results of nonlinear time history analysis including damping nonlinearity. The fitness function of the optimum procedure was constructed based on the ratio of maximum spectral value and target GERS (General Equipment Ruggedness Spectra). The results show the good improvements of fitness fur adequate retrofitting pattern. Especially, the improvements of fitness were remarkable when the damping exponents are proper.

• Electronics and Telecommunications Trends
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• v.13 no.3 s.51
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• pp.27-41
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• 1998

본 고에서는 최근 들어 멀티서비스 통합망 솔루션으로 많은 관심을 끌고 있는 패킷 음성 기술에 대해 조사 분석한 내용을 기술한다. 패킷 음성 기술은 데이터 서비스 위주의 패킷망에 음성 트래픽을 통합하여 전달해 줌으로써 가입자 관점에서는 저가에 음성 서비스를 제공받게 되고, 망사업자 입장에서는 망 구축운용 비용의 절감과 망자원 사용 효율의 개선, 서비스 제공 능력의 강화에 의한 경쟁력 확보를 보장해 준다. 멀티서비스 통합 통신망의 구축은 초기에는 주로 업무용 가입자들을 주요 대상으로 WAN/LAN 도메인에서 진행이 되고, 이후 일반 가입자들을 대상으로 공중망으로 확산될 것으로 예상된다. 패킷 음성 기술의 기술적 대안으로는 인터넷을 통한 Voice over Internet (VoIP) 기술과 ATM 망을 통한 Voice and Telephony over ATM (VTOA) 기술 및 프레임 릴레이 망을 이용하는 Voice over Frame Relay (VoFR) 기술이 많은 관심을 끌고 있으며, 표준규격의 추진과 시스템 개발이 활발히 진행되고 있는 상태이다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.20-24
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• 2000

VoIP는 Packet Netwark(ATM, xDSL, Frame Relay, Cable Network)망을 이용하여 음성데이터를 전송 하는 기술로서 PSTN을 통해 음성데이터를 전송하는 것보다 비용절감의 효과가 크다. 본 연구에서는 최적의 VoIP 서비스 제공을 위한 음성/데이터 통합 네트워크 망을 설계하기 위하여 IP와 ATM을 이용한 서로 다른 2개의 망을 설계하여 지연과 Routing 정책, Traffic 추가 후 지연현상에 대하여 살펴보았다. 지연은 순수한 VoIP 망을 구성 할 경우 8-10ms. VoIP+ATM으로 망을 구성 할 경우 2ms로 나타났고, 라우팅 정책(RIP, IGRP, OSPF 적용)에서는 IP 또는 IP+ATM으로 망을 구성 할 경우 RIP는 25ms, IGRP는 22ms로 나타났고, OSPF를 이용할 경우 14ms로 평가되어 OSPF를 이용한 라우팅 정책을 설정하는 것이 바람직하다고 볼 수 있다. 결론적으로 본 연구의 결과 VoIP망을 구성 할 경우 IP+ATM을 기반으로 구축하면 보다 더 효과적인 인터넷 망을 구성할 수 있음을 확인하였다.

• The Journal of Society for e-Business Studies
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• v.6 no.2
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• pp.25-38
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• 2001

ATM is the transport method for the broadband integrated services digital networks(B-ISDN). It may replace existing LAN, MAN and WAN technologies such as CSMA/CD, FDDI, Frame relay, X.25, etc. But it is more complicate than existing network technologies. One of the main difficulties in ATM network is performance management. Specifically, the problems are evaluating the performance and tuning the values of the performance parameters, The goal of this paper is to introduce a system architecture designed for ATM network performance management, The major ingredients of the system are generic performance parameters In be measured from ATM network, performance evaluation models and decision criteria concerning the network performance. In this paper, general requirements for performance management application in ATM network are discussed.