• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.413-414
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• 2012

본 연구는 고속 PLC(PLC: Power Line Communications)를 구현하기 위해, 전력선을 통해서 통신을 하고, 시스템 간의 정보를 교환하는 매체접근제어(MAC) 계층 적합성 인증하기 위한 실험에 관한 연구이다. 연구과정은 물리계층(PHY) 및 매체제어접근계층(MAC) 규격을 바탕으로 하고, 200Mbps의 고속전송이 가능한 PLC 칩(Chip)을 대상으로 한다.

• Information and Communications Magazine
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• v.19 no.9
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• pp.77-85
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• 2002

In this paper, we introduce an ADSRC(hdvanced DSRC) OFDM packet communication system which has been developed by ETRI. The ADSRC system is targeted to provide high terminal mobility, high data rate and seamless service in roadside environment for mobile office services. We discuss the requirements of the ADSRC communication system for mobile office services, and the system design specification to meet them with regard to air interface. The ADSRC packet communication systems consist of the MAC processor block, the OFDM packet modem block and the RF block. The MAC processor block handles medium access control and the test. The OFDM packet modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. We describe the ADSRC packet communication system architecture and the ADSRC system protocol.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.256-258
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• 1999

본 논문에서는 DS-CDMA 시스템에서 예약 기반 MAC 플로토콜의 성능을 분석한다. 본 논문에서 고려하고 있는 예약 기반 MAC 프로토콜은 NAK 방식과 Request 큐잉 방식이다. NAK 방식은 예약 요구를 수락할 수 없는 경우에 NAK를 전송하여 전송 불가를 통지하는 방식이며, Request 큐잉 방식은 예약 요구를 수락할 수 없을 경우에 기지국에 예약 요구 패킷을 저장하는 방식이다. 그리고 이러한 두 방식에 채널 유지 기능을 추가한 방식을 함께 고려한다. 각 방식에서 패킷의 길이를 변화시키면서 수율과 평균 전달 지연 시간을 비교하였다. 성능 분석 결과 패킷의 길이가 짧은 경우에는 예약 방식의 성능이 매우 낮으며, 패킷의 길이가 길어지면 성능이 향상되는 것을 알 수 있다. 그리고 채널 유지 기능을 추가함으로서 전반적인 성능이 향상되며, 채널 유지 방식에서는 패킷간의 도착 시간, 예약 과정의 지연 시간 등을 고려해서 최적의 채널 유지 시간을 설정해야 함을 알 수 있다.

• ETRI Journal
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• v.37 no.6
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• pp.1096-1107
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• 2015

This paper presents a dynamic retry adaptation scheme for H.264 HD video, called DRAS.264, which dynamically adjusts the retry limits of frames at the medium access control (MAC) layer according to the impact those frames have on the streamed H.264 HD video. DRAS.264 is further improved with a bandwidth estimation technique, better prediction of packet delays, and expanded results covering multi-slice video. Our study is performed using the Open Evaluation Framework for Video Over Networks as a simulation environment for various congestion scenarios. Results show improvements in average peak signal-to-noise ratios of up to 4.45 dB for DRAS.264 in comparison to the default MAC layer operation. Furthermore, the ability of DRAS.264 to prioritize data of H.264 bitstreams reduces error propagation during video playback, leading to noticeable visual improvements.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.739-742
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• 2000

In this paper, we evaluate the throughput and delay performance of a wireless Local Area Network(WLAN) employing the OFDM-based IEEE 802.lla Medium Access Control(MAC) protocol by compute. simulations under wireless indoor. channel. Packet Error Rate(PER) is also investigated for the various Eb/No. It is shown that, with soft-decision Viterbi decoder, throughput and delay performance are close to those of error-free channel at Eb/No above 8dB and PER is about 2${\times}$10$\^$-5/ at Eb/No=10dB.

• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.59-62
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• 2007

In this paper, we introduce a reliable, scalable, and cost-effective switchless wavelength division multiplexing (WDM) network based on a quality-of-service supporting reservation-based medium access control (MAC) protocol. The protocol not only provides both packet and circuit switching but also supports multicasting. The network efficiency is significantly increased by spatially reusing wavelengths and exploiting multiple free spectral ranges (FSRs) of arrayed waveguide grating (AWG) employed in the architecture. We have demonstrated the feasibility of this architecture by simulating in $Optsim^{TM}$.

• Journal of information and communication convergence engineering
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• v.5 no.1
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• pp.29-34
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• 2007

This paper proposes a MAC protocol for real-time VBR (rt-VBR) services in wireless ATM networks. The proposed protocol is characterized by a contention-based mechanism of the reservation request, a contention-free polling scheme for transferring the dynamic parameters, and a priority scheme of the slot allocation. The design objective of the proposed protocol is to guarantee the real-time constraint of rt-VBR traffic. The scheduling algorithm uses a priority scheme based on the maximum cell transfer delay parameter. The wireless terminal establishes an rt-VBR connection to the base station with a contention-based scheme. The base station scheduler allocates a dynamic parameter minislot to the wireless terminal for transferring the residual lifetime and the number of requesting slots as the dynamic parameters. Based on the received dynamic parameters, the scheduler allocates the uplink slots to the wireless terminal with the most stringent delay requirement. The simulation results show that the proposed protocol can guarantee the delay constraint of rt-VBR services along with its cell loss rate significantly reduced.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.92-94
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• 2007

IEEE 802.11 WLAN(Wireless LAN)은 그 편리함과 효율성으로 인하여 수요의 증가 및 기술의 개발이 계속되고 있다. MAC(Medium Access Control)계층 중 기본적인 매체 접근 방식인 DCF(Distributed Coordination Function)는 CSMA/CA 알고리즘을 이용하여 충돌문제를 해결한다. 본 논문에서는 IEEE 802.11 MAC 계층 DCF 방식에서 스테이션간의 충돌확률을 줄이기 위하여 각 스테이션의 경쟁 윈도우 범위 사이에서 임의의 Backoff Time을 설정하는 것에 착안하여 최소 경쟁 윈도우(Minimum Contention Window)의 값이 성능에 어떠한 영향을 미치는가를 시뮬레이션을 이용하여 분석한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.1024-1026
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• 2012

본 논문에서는 UWB 기술 기반 WiMedia Distributed Medium Access Control (D-MAC) 프로토콜에서, 디바이스들의 이동성으로 인해 발생하는 Distributed Reservation Protocol (DRP) 예약 충돌 현상을 분석한다. 그리고 DRP 예약 충돌 시 발생하는 성능 저하를 감소시키기 위해 DRP Conflict Resolution 방식과 DRP 릴레이 통신 기술을 제안한다. 본 논문에서 제안하는 DRP 릴레이 통신 프로토콜은 충돌대상 디바이스에게 예약된 자원을 유지할 수 있도록 Direct Link 뿐만 아니라, DRP 예약 충돌 시 릴레이 노드를 경유하여 또 다른 Indirect Link 링크를 빠르게 예약할 수 있는 분산적인 자원 예약 프로토콜을 제안한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.93-100
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• 2003

In this farer, An ADSRC(Advanced Dedicated Short Range Communication) packet communication system developed by ETRI is introduced. The ADSRC system has been developed to provide high-speed, short-range wireless racket communication in roadside environment for mobile office services. The requirements of the ADSRC system for mobile office services and the system design specification to meet them with regard to mobile of nce environment are discussed. The ADSRC packet communication systems consist of the MAC(Medium Access Control) Processor block the OFDM() modem block and the RF block. The MAC processor block handles medium access control. The OFDM modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. The ADSRC packet communication system architecture is described.