• 제목/요약/키워드: 통신중계

검색결과 910건 처리시간 0.036초

Study on Design of IP PBX of Distribute Base on SIP Protocol Stack (SIP프로토콜 스텍을 기반으로 하는 분산형 IP PBX 단말기 설계)

  • Yoo Seung-Sun;Yoo Gi-Hyoung;Lim Pyung-Jong;Hyun Chul-Ju;Kwak Hoon-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제31권4A호
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    • pp.377-384
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    • 2006
  • According to fast VoIP technology development, more and more companies change voice network into IP based network among branch offices. IP PBX, which is deployed up to now, composed of IP phone and VoIP Gateway. Every telphone has replaced with If phone which support VoIP and VoIP gateway is installed in PBTN connection point to relay voice data. It can reduce the communication expense of International call, long distance call and call between a headquater and a trance because it uses internet line. In this paper, IP PBX is implemented that can distribute call using PBX network only usig personal terminal without Proxy Server. Depending on Role, terminal can be registered Master, Server and Client and it is verified in terms of performance and validation.

Capacity Analysis of IEEE802.16j MMR System Using Directional Antenna (지향성 안테나를 사용하는 IEEE802.16j 멀티 홉 릴레이 시스템의 용량 분석)

  • Kim, Seung-Yeon;Yoo, Chang-Jin;Kim, Se-Jin;Ryu, Seung-Wan;Cho, Choong-Ho;Lee, Hyong-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제34권2B호
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    • pp.170-177
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    • 2009
  • In this paper, we propose the structures of the NBTC (Narrow-Beam Trisector Cell) and the WBTC(Wide-Beam Trisector Cell) in which directional antennas both at the base station and at the relay station are used. We analyze and compare total capacity of the both systems taking the co-channel interference into consideration for two channel models. Through analysis, we find the effect of LOS (Lind of Sight) path to the total capacity of NBTC structure and that of WBTC structure. Our work may be useful as a guideline to control the interference for the next generation mobile communication and WiBro systems using multi-hop relays.

RFID Distance Bounding Protocol Secure Against Mafia and Terrorist Fraud (테러리스트 공격과 마피아 공격에 안전한 RFID 거리 제한 프로토콜)

  • Kwon, Hye Jin;Kim, Soon Ja
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제39A권11호
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    • pp.660-674
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    • 2014
  • RFID system has been used in a variety of services. So, a lot of attacks like a free ride on the service, leakage of property or personal information are known. Therefore, the solutions that address these attacks have been proposed. Among the attacks, mafia fraud, a kind of relay attack, can not be addressed by common authentication protocol. So, Hancke and Kuhn used distance bounding protocol for RFID authentication. After that, Munilla and Peinado modified HK protocol by adding void challenge. So the mafia fraud success probability of adversary is lower than probability of HK protocol. Ahn et al. proposed a protocol that reduces number of a hash computation and traffic than MP protocol. Here, we show that MP protocol can not defend the terrorist fraud and is vulnerable to noise. And we show that also AYBN protocol is vulnerable to mafia fraud and key leakage. Moreover, we propose a new protocol and our experimental results show that our protocol is secure to terrorist and mafia fraud.

A Study of Balanced TCP Bandwidth Allocation over Wired and Wireless Heterogeneous Network (유무선 혼합 망에서 TCP의 공평한 대역폭 분배를 위한 연구)

  • Kim, Seong-Chul;Cho, Yong-Bum;Moon, Il-Young;Cho, Sung-Joon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 한국해양정보통신학회 2005년도 춘계종합학술대회
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    • pp.113-116
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    • 2005
  • In general, multiple mobile hosts (MH) access at a base station (BS) that terminates the wired link and relays data flow to the wireless link in wired and wireless heterogeneous network. In this network, the BS is tend to be a bottleneck and to degrade a network performance. Many studies have been done throughout several protocol layers. Especially on the transport layer, many techniques were studied to enhance TCP performance. But most of them are concerned to enhance TCP throughput and TCP fairness is hardly considered. In this paper, an algorithm for enhancing TCP fairness is proposed and its performance is verified by ns-2 simulation.

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DT-GPSR: Delay Tolerant-Greedy Perimeter Stateless Routing Protocol (DT-GPSR: 지연감내형 GPSR 라우팅 프로토콜)

  • Nam, Jae-Choong;Cho, You-Ze
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제41권2호
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    • pp.189-197
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    • 2016
  • Mobile ad-hoc networks (MANETs) experience frequent link disconnections due to non-uniform node distribution and mobility. Thus, end-to-end path establishment-based routing protocols cause frequent transmission failures in MANETs, resulting in heavy control messages for path reestablishment. While location-based MANET routing protocols, such as Greedy Perimeter Stateless Routing (GPSR), use location information to forward messages in a hop-by-hop routing fashion without an end-to-end path establishment procedure, such protocols encounter communication void problems when message forwarding to the next hop fails due to the absence of a relay node. Therefore, to solve this problem, this paper proposes a Delay Tolerant-GPSR (DT-GPSR) protocol, which combines Delay Tolerant Networking (DTN) technology with the GPSR protocol. The performance of DT-GPSR is compared with the performances of the original GPSR and PRoPHET routing protocols through simulation using NS-2. The simulation results confirm that DT-GPSR outperforms GPSR and PRoPHET in terms of the message delivery ratio and message delivery delay.

Design of Antenna for Beam Scanning for Dual-Band base station (이중대역 기지국용 빔 스캔 안테나 설계)

  • Ko Jin-Hyun;Jang Jae-Su;Ha Jae-Kwon;Park Sae-Houn
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 한국해양정보통신학회 2006년도 춘계종합학술대회
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    • pp.632-636
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    • 2006
  • It is needed to use the beam scanning to control the cell coverage of the base station considering operation conditions, season, time period, radiation character and mobility of customers and vehicles for varied wireless communication service and quality improvement. This paper proposes a mobile antenna system which can obtain the characteristics of the beam scanning by controlling the directivity depending on the operation condition. Radiation block is made of 2 sub-array of $1\times3$ patched antennas for ITS of 5.8GHZ bandwidth with the gain of 13dBi, and of 2 sub-array of single patched antenna for WiBro of 2.3GHZ bandwidth with the gain of 12dBi. RF module is made of a switch, an amplifier, a PAD, a 3-Bit phase shifter, and a power divider. The system is able to control the beam tilting with electronic methode by using 3-bit phase shifter$(45^{\circ},\;90^{\circ},\;180^{\circ})$.

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Environment Monitoring System Using Autonomous Mobile Robot (자율 주행 로봇을 이용한 환경 모니터링 시스템)

  • Jeong, Hye-jin;Kim, Won-jung;Son, Cheol-su;Cho, Byung-lok;Yang, Su-yeong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 한국해양정보통신학회 2009년도 추계학술대회
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    • pp.1038-1041
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    • 2009
  • Wireless sensor network with wireless sensor nodes which equipped with temperature, humidity, illumination, or soil sensor etc, get a natural environment information and analyze and utilized variety way.these network consist of a short distance wireless communication and multi-hop techniques with multiple nodes equipped low-power wireless transceivers. so the characteristic of the data collected through the wireless sensor network is obtained from compact nodes within a limited range. However, to get a data from the wireless sensor nodes scattered in a wide range, this network needs a wireless transceiver that consumes many power or a lot of intermediate nodes. then, merit of low cost and low electrical energy decrease. To solve this problem, this paper offers environment monitoring system using autonomous mobile robot that collect data from groups of each sensor networks scattered widely.

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A Study on Development of High-speed Data Optical Transmission ADC for Minimization of Time Delay (지연시간 최소화를 위한 고속 데이터 광 전송용 ADC 개발에 관한 연구)

  • Park, Jong-Dae;Park, Chan-Hong;Park, Byeong-Ho;Ahn, Chang-yeop;Seong, Hyeon-Kyeong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 한국정보통신학회 2014년도 추계학술대회
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    • pp.182-185
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    • 2014
  • In this paper, the ADC performs research and development for high speed data transfers to minimize the optical delay. Have more $6{\mu}s$ delay in the data signal converting optical repeater transmission system existing there has been a limit on the high-speed data transmission, and signal conversion. The need to develop a new technique to reduce the delay in time within $2{\mu}s$ data signal converted by using this direct conversion system. It is desired the development of the core technologies necessary for the signal transduction component, such as mobile communications LTE, LTE advanced service transport network is established, the delay time $3{\mu}s$ technology for reducing the delay time in the signal converting a revolutionary step is applied in this paper we have developed an ADC.

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A Study on Design Method of Smart Device for Industrial Disaster Detection and Index Derivation for Performance Evaluation (산업재해 감지 스마트 디바이스 설계 방안 및 성능평가를 위한 지표 도출에 관한 연구)

  • Ran Hee Lee;Ki Tae Bae;Joon Hoi Choi
    • Smart Media Journal
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    • 제12권3호
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    • pp.120-128
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    • 2023
  • There are various ICT technologies continuously being developed to reduce damage by industrial accidents. And research is being conducted to minimize damage in case of industrial accidents by utilizing sensors, IoT, big data, machine learning and artificial intelligence. In this paper, we propose a design method for a smart device capable of multilateral communication between devices and smart repeater in the communication shaded Areas such as closed areas of industrial sites, mountains, oceans, and coal mines. The proposed device collects worker's information such as worker location and movement speed, and environmental information such as terrain, wind direction, temperature, and humidity, and secures a safe distance between workers to warn in case of a dangerous situation and is designed to be attached to a helmet. For this, we proposed functional requirements for smart devices and design methods for implementing each requirement using sensors and modules in smart device. And we derived evaluation items for performance evaluation of the smart device and proposed an evaluation environment for performance evaluation in mountainous area.

Development of an IoT Smart Home System Using BLE (BLE통신을 이용한 IoT 스마트홈 모니터링 시스템 개발)

  • Duong, Cong Tan;Kim, Myung Kyun
    • Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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    • 제8권6호
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    • pp.909-917
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    • 2018
  • Recently, the Internet of Thing (IoT) technology is expanding explosively in the number of devices and applications in many application areas. In IoT systems, sensors and actuators are connected to the Internet and cooperate to do some applications by exchanging information. In this paper an IoT smart home system is developed to monitor and control home devices easily. Our system consists of sensor devices, IoT gateways, and an IoT server. Sensor devices developed using Rfduino sense the physical world and transmit their data using BLE to the IoT server thru the IoT gateway. We implemented the IoT gateway using Raspberry Pi and the IoT server using ARTIK cloud. We installed our system and made a test in our lab, which showed that our system can be installed and managed easily and extended its functionality in an easy way. By taking advantage of the rule mechanism and action messages of ARTIK cloud, we implemented the control of device parameters easily by sending action messages to the ARTIK cloud.