• 한국통신학회논문지
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• 제37권3A호
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• pp.141-150
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• 2012

본 논문에서는 UWB 기술 기반 WiMedia Distributed Medium Access Control (D-MAC) 표준 프로토콜에 적용할 수 있는 릴레이 자원 예약 프로토콜을 제안한다. 그리고, 무선 채널 상태에 따라 변화하는 UWB 링크 전송속도에 적응적인 릴레이 노드 선정 알고리즘을 제안한다. 본 논문에서 제안하는 UWB 링크에 적응적인 릴레이 통신 프로토콜은 분산적인 D-MAC 표준 기술과 호환성을 갖고, 각 디바이스에서 독립적으로 실행되는 Satisfaction of QoS (SoQ) 기준에 따라 실행된다.

• Journal of Communications and Networks
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• 제17권2호
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• pp.172-183
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• 2015

To provide an efficient link maintenance approach, we propose a cross layer medium access control (LM-MAC) protocol for multichannel cognitive radio ad hoc networks. Link establishment and reliable transmission are two key problems for a perfect link maintenance mechanism. Since the cognitive user (CU) pairs have to reestablish their links each frame, in the proposed MAC protocol, three different access modes are designed to guarantee transmission efficiency in continuous frames. To enhance the transmission reliability, each CU will create a father spectrum list (FSL) after joining in the network. FSL is divided into three groups of sub-channels with different functions to compensate the packet loss caused by the primary users' appearance and the deep fading. Meanwhile, since the transmitter and the receiver will share the same FSL, periodical cooperative sensing is adopted to further optimize the former problem. Finally, compared with the existing opportunistic multichannel (OMC)-MAC protocol, the proposed LM-MAC protocol achieves better system performance in terms of saturation throughput, continuity and access delay.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.878-884
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• 2013

본 논문에서는 애드 혹 네트워크에서 데이터 프레임을 전송할 때마다, 전송 파워를 동적으로 바꾸어 전달하는 MAC 프로토콜을 제안하였다. IEEE 802.11과는 달리, 주변 노드들의 전송을 방지하기 위한 RTS/CTS 프레임을 사용하지 않았다. 그 대신에 송신 터미널과 수신 터미널 사이의 RTS/CTS 프레임 내에 채널이득과 거리 정보 넣어 전송하였다. 이들 정보는 동적으로 전송파워 값을 구하는데 사용된다. 시뮬레이션 결과, 제안한 MAC 프로토콜이 GMAC과 비교하여 프레임 평균 전달률은 증가했고, 평균 지연에서는 감소하는 성능을 보였다.

• 전자통신동향분석
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• 제18권3호통권81호
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• pp.11-20
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• 2003

최근 SCTP(Stream Control Transmission Protocol)는 TCP/UDP 이후의 차세대 수송계층 프로토콜로서 주목 받고 있다. SCTP는 기존 TCP 및 UDP의 문제점을 극복하도록 설계되었으며 특히 multi-streaming 및 multi-homing 특성을 제공한다. 본 고에서는 SCTP 프로토콜의 기본 특징에 대하여 알아보고, 현재 논의중인 확장작업의 주요 골자를 살펴본다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(3)
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• pp.189-192
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• 2002

This paper has been studied some security issues o( stream control transmission protocol and designed some functional requirement for IPsec and IKE to facilitate their use for securing SCTP. In particular, some additional support in the form of new ID type in IKE and some implementation choices in the IPsec processing to accomodate for the multiplicity of source and destination addresses associated with a single SCTP association.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1629-1632
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• 2003

Generally an increasing number of recent applications have found TCP too limiting. There are some characteristics in the transmission of document and binary data which some transmission delay are tolerant but the content must completely be transferred. However voice signals are more sensitive with not some packet loss but some transmission delay. Therefore, Stream Control Transmission Protocol(SCTP) is proposed to minimize the delay and packet loss in the field of delivery of voice signal. SCTP is designed to transport PSTN signalling messages over IP networks, but is capable of broader applications. In this paper, the architecture of SCTP implementation is designed and some interface of SCTP software library which are implemented are specified.

• 한국정보통신학회논문지
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• 제17권6호
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• pp.1324-1329
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• 2013

본 논문에서는 WiMedia D-MAC 기술 기반 Wireless USB 프로토콜에서 분산적인 SoQ기반 Wireless USB Channel 자원 할당 방법의 성능을 분석하고, QoS 성능 향상을 위해 릴레이 통신 기술을 적용한 SoQ 릴레이 전송 프로토콜을 제안한다. 본 논문에서 제안하는 SoQ 릴레이 전송 프로토콜은 Satisfaction of QoS (SoQ) 알고리즘을 각 단말 디바이스 내 WiMedia D-MAC 계층에서 분산적으로 실행하고, 충돌대상 디바이스에게 예약된 QoS 자원을 유지할 수 있도록 Direct Link 뿐만 아니라 릴레이 노드를 경유하여 또 다른 Indirect Link 링크를 예약할 수 있는 자원 예약 프로토콜을 제안한다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.413-418
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• 2000

For Pneumatic system control, we need a data transmission system with high speed and high realibility for information interchange between main computer and solenoid valves and I/O devices. This paper presents a set of design techniques for a data communication system that is mainly used for pneumatic system control. For this purpose, we first designed hardware modules for an interface between central control module and local node that handles the operation of solenoid valves. In addition we developed a communication protocol for construction of RS-485 based multidrop network, and this protocol is basically designed with a kind of polling technique. Finally we evaluated performance of the developed system. The field test results show that, even under high noise environment, the data transmission of 375Kbps rate is possible up to 1,000m without using repeater. In addition, the system developed in this research is proved to be used easily for extension of a communication network because of its module structure.

• 한국정보과학회논문지:정보통신
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• 제29권5호
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• pp.495-500
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• 2002

We propose a new estimation method for rate adjustment in the face of a packet loss in the TFRC protocol, a TCP-Friendly congestion control protocol for UDP flows. Previous methods respond in a sensitive way to a single packet loss, resulting in oscillatory transmission behavior. This is an undesirable for multimedia services demanding constant bandwidth. The proposed TFRC provides more smooth and fair (against TCP flows) transmission through collective response based on multiple packets loss events. We show our "Exponential smoothing method" performs better than known "Weight smoothing method" in terms of smoothness and fairness.

• Journal of Communications and Networks
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• 제16권3호
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• pp.311-321
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• 2014

This paper focuses on contention-based medium access control (MAC) protocols used in wireless local area networks. We propose a novel MAC protocol called adaptive backoff tuning MAC (ABTMAC) based on IEEE 802.11 distributed coordination function (DCF). In our proposed MAC protocol, we utilize a fixed transmission attempt rate and each node dynamically adjusts its backoff window size considering the current network status. We determined the appropriate transmission attempt rate for both cases where the request-to-send/clear-to-send mechanism was and was not employed. Robustness against performance degradation caused by the difference between desired and actual values of the attempt rate parameter is considered when setting it. The performance of the protocol is evaluated analytically and through simulations. These results indicate that a wireless network utilizing ABTMAC performs better than one using IEEE 802.11 DCF.