• Journal of Digital Contents Society
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• v.10 no.2
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• pp.279-289
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• 2009

As the TCP is the protocol designed for the wired network that packet loss probability is very low, because TCP transmitter takes it for granted that the packet loss by the wireless network characteristics is occurred by the network congestion and lowers the transmitter's transmission rate, the performance is degraded. In this article, we suggest the newly improved algorithm using two parameters, the local retransmission time value and the local retransmission critical value to the BS based on the Snoop. This technique adjusts the base stations local retransmission timer effectively according to the wireless link status to recover the wireless packet loss rapidly. We checked that as a result of the suggested algorithm through various simulations, A-Snoop protocol improve more the wireless TCP transmission rate by recovering the packet loss effectively in the wireless link that the continuous packet loss occur than the Snoop protocol.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.429-436
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• 2017

Since the telemetry performance using the time-delayed data dissipates the wireless channel resources, we propose the spectral efficient retransmission scheme in this paper. In the proposed scheme, the telemetry data is retransmitted based on triggered memory to improve the spectral efficiency. The proposed scheme minimizes the error caused by multipath fading, antenna pattern as well as the error caused by the flight events. In the flight simulation data, we show the proposed scheme improves the telemetry performance based on spectral efficient retransmission.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.447-454
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• 2006

An ad-hoc network routing protocol, AODV(Ad-hoc On-demand Distance Vector) initially uses ERS(Expanding Ring Search) algorithm to control the RREQ(Route Request) retransmission in the route discovery process. Because ERS uses the fixed NTT(Node Travesal Time), it does not reflect accurately ad-hoc network environment. In this paper, we propose an improved ERS algorithm which lowers the retransmission rate. It uses RREP(Route Reply) and gives different weights in NTT of each node in accordance with the adjacency to an originating node. To show the effectiveness of the proposed algorithm, we perform a simulation using ns2. The simulation results showed that the proposed algorithm has better performance than existing algorithms.

• Journal of Korea Multimedia Society
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• v.13 no.10
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• pp.1525-1533
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• 2010

With the digital terrestrial television broadcasting transition, terrestrial television broadcasting have required the replacement of retransmission facilities for the analog broadcasting installed in the existing apartment, building, cable TV station, MATV system and so on. In addition, new standards have been enacted for retransmission of the digital television broadcasting in MATV system. To deal with this issue, in this paper, we propose a new 8-VSB remodulator that can retransmit signals of the terrestrial digital television broadcasting. Moreover, we present a standard and the process composition of the 8-VSB remodulator, and an experimental environment configuration for performance evaluation. To achieve this, we have implemented the 8-VSB remodulator with the sequential process components comprised of the RF signal retransmission, the TS stream modulator, the RF signal reception and demodulation. Through the simulation, we analyze the performance standard from the measured data such as spurious and phase noise. And then, we measure SNR and EVM of each attenuation step of the signal obtained by the signal processor and the 8-VSB remodulator with the same retransmission environment and conditions. Experimental results show that both the 8-VSB remodulator and the signal processor can be used as equipment for the retransmission of the terrestrial digital television broadcasting. In addition, the 8-VSB remodulator performed well to improve the transmission efficiency for the digital broadcasting signal, compare to the existing signal processor.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.72-75
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• 1986

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.889-893
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• 1996

• ETRI Journal
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• v.27 no.1
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• pp.1-12
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• 2005

We propose a heuristic buffer management scheme that uses both positive and negative acknowledgments to provide scalability and reliability. Under our scheme, most receiver nodes only send negative acknowledgments to their repair nodes to request packet retransmissions while some representative nodes also send positive acknowledgments to indicate which packets can be discarded from the repair node's buffer. Our scheme provides scalability because it significantly reduces the number of feedbacks sent by the receiver nodes. In addition, it provides fast recovery of transmission errors since the packets requested from the receiver nodes are almost always available in their buffers. Our scheme also reduces the number of additional retransmissions from the original sender node or upstream repair nodes. These features satisfy the original goal of treebased protocols since most packet retransmissions are performed within a local group.

• Journal of the Semiconductor & Display Technology
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• v.14 no.1
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• pp.51-53
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• 2015

H.264/AVC is international video coding standard, which shows improved code and efficiency than the existing video standards. H.264/AVC proposes data partitioning method that considerably to be an effective layering technique which separates important addressing data from the residual data. UEP(Unequal Error Protection) turbo code of H.264/AVC uses retransmission system to get the UEP effectively. However, Data partitioning system of H.264/AVC is inefficient method in turbo code of H.264/AVC. Based on this observation, we propose the new UEP turbo code algorithm that reconstructs input sequence of turbo code without retransmission system.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.4
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• pp.687-698
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• 1997

In this paper, a Variation of Blast with Go-Back-N(V-BGBN) protocol is proposed, which differs from Blast with Go-Back-N(BGBN) and Blast with Full Retransmission on Error(BFRE) protocols in the retransmission strategy of packets. Performances of these three protocols under correlated packet errors are analyzed. Throughput efficiency of an arbitrary packet is obtained under the assumption that the round trip delay and the packet length are respectively constant. Recursive formula and difference equations are used as analytical tools. Correlation of packet errors is modelled by a two state Markov chain. The throughput efficiencies under these protocols are compared. V-BGBN protocol is shown to be superior to other two protocols in high speed network.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.293-296
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• 2009

최근에 다양한 네트워크의 기술들이 존재하고 개발되어지고 있다. 이러한 네트워크 기술들을 효과적으로 사용하기위해서 버티컬 핸드오버가 다양한 측면에서 연구되어지고 있다. 버티컬 핸드오버는 단말기가 이종망에서 더 나은 성능을 가진 네트워크로 끊김없는 서비스를 제공하는 핸드오버 기술이다. 버티컬 핸드오버를 수행하는 동안에 라우터간 시그널링의 지연과 더불어 인증과 등록절차에 대한 시간지연으로 인하여 혼잡한 상황이 아님에도 불구하고 TCP에서는 혼잡한 상황으로 인식하여 성능이 낮아지는 문제가 발생한다. 또한, 버티컬 핸드오버를 수행하는 중에 링크의 특성이 다르고 대역폭이 달라서 패킷의 순서번호가 일치하지 않아서 잘못된 빠른 재전송(false fast retransmission:FFR) 발생하고 이러한 현상들은 TCP 처리량의 저하를 가져온다. 논문에서는 이러한 문제를 해결하기 위한 방법들에 대한 동향을 조사 해보았다.