• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2457-2462
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• 2010

In this paper, We applied CCI canceller to remove multiple access interference in co-channel environment and improved performance of Impulse Radio UWB system. Also, we have evaluated the performance of UWB system with Truncated Type-II Hybrid ARQ scheme for achieving high quality data transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.215-223
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• 2008

Retransmission signals from relays to destination when the destination fails to decode received signal from the source in Automatic Repeat Request (ARQ) protocol make the destination receive signals more reliably. With using omni -direction antenna in the practical system, in communication range of both the source antenna and the destination antenna, there are some relays that can be used to transmit signal to the destination. However, using all relays to transmit signal consume power and bandwidth. In this paper, we propose a new protocol in which the best relays are chosen based on threshold of distance from the source to the relay and the relay to the destination when the relays use decode- and forward (DF) protocol. Simulation results prove the efficiency of the protocol when we compare using only the best relays with using all relays to transmit signal to the destination.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1473-1478
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• 2005

In this paper, we proposed UWB system with variable rate in piconet environment that several wireless devices moves as variable. And, we analyzed the performance of UWB system according to multiple access interference and transmission rate. Also, we have evaluated the performance of m system with Truncated Type-II Hybrid ARQ scheme fer achieving high qualify data transmission.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.26-35
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• 1995

Bo-Back-N ARQ is widely used in packet networks for error and flow control methanisms. This paper analyzes the network throughput under the go-back-N schem. Contrast to other analytic methods which assume independent frame losses or the first order Markov frame analytic methods which assume independent frame losses or the first order Markov frame losses concoptually, the proposed method takes into account the correlation between successive frame losses in a congested node. Computer simulation shows that our method generates more accurate performance results that independent assumption method. We apply the proposed method to analyze the performance of BWM in high speed networs. Our results show that BWM maintains the independence between traffic streams.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.59-64
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• 2001

This paper analyzes the performance of the several types of ACL(Asynchronous ConnectionLess) packets used in Bluetooth according to a BER(Bit Error Rate) and a packet length and proposes an optimal packet type and an optimal size of the packet being able to be used under the given BER. This paper proposes how to obtain the optimal packet type and the optimal size of the packet maximizing the performance measure under the given BER. In addition, this paper shows that the optimal type and size of the packet maximizing the throughput are different from those maximizing the mean transmission time. This occurs because the Bluetooth uses not only one type of packet but also various types of packets.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.125-128
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• 2011

기회적 중계 기술(opportunistic relaying)은 중계기를 사용하여 다이버시티 이득을 얻을 수 있는 효율적인 기술로 평가되고 있다. 기회적 중계 기술에서는 가장 좋은 중계기를 선택하여 송신기의 전송 신호를 재전송하게 되는데, 중계기 선택은 채널 정보(channel state information)를 이용하여 이루어진다. 본 논문에서는 하이브리드 ARQ 기반 기회적 중계 기술에서 중계기를 선택할 때 사용하는 채널 정보(channel state information)가 지연된 정보일 때, 시스템의 불능 확률(outage probability) 및 처리량(throughput)을 분석한다. 컴퓨터 시뮬레이션을 통해 분석이 정확한지 검증한다.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.513-516
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• 2000

In this paper, we investigate the effect of the retransmission limit both the system capacity and the average number of retransmissions in a voice/data DS-CDMA system. Basically, we consider the IS-95 type reverse link of the CDMA system, which supports two kinds of services: a general voice and a packetized data service. ARQ is used for the reliable data transmission. Convolutional code is used for FEC and CRC-CCITT code is used for the error detection in ARQ. The result shows that the number of concurrent data users decreases as we reduce the number of the retransmissions. However, at the same time, we can also reduce the average number of retransmissions. Concluding1y, we can select the retransmission limit so as to reduce large amount of' retransmissions with small sacrifice in the system capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9A
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• pp.1465-1474
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• 2001

본 논문에서는 BER(Bit Error Rate)과 패킷 길이에 따라 블루투스의 다양한 ACL(Asynchronous Connection Less) 패킷 종류들의 성능을 분석하였고 주어진 BER에서 적합한 패킷의 최적 종류와 길이를 제안하였다. ACL 패킷 중 DM(Data Medium Rate) 형은 1/3FEC과 2/3FEC과 ARQ 방식을 사용하지만 DH(Data High rate) 형은 2/3FEC과 ARQ만을 사용한다. 이러한 특징은 잡음이 존재하는 무선 링크 상에서 메시지의 평균 전송 시간과 처리율과 같은 성능 지표에 영향을 준다. 이러한 ACL 패킷의 PER(Packet Error Rate)을 무선 링크의 BER과 패킷 유료부하 길이의 항으로 제시하고 PER과 이에 따른 ARQ 방법에서의 재전송 회수를 고려하여 메시지의 평균 전송시간 및 전송 효율을 구하는 방법을 제시하였다. 본 논문에서는 이를 이용하여 주어진 BER에서 성능 지표를 최대화하는 ACL 패킷의 최적 종류와 최적 길이를 제시하였다. 이를 기초로 전송 효율을 최대화하는 최적 패킷의 종류와 길이가 평균 전송 시간을 최소화하는 패킷의 종류와 길이는 다르다는 것을 보였다.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.319-322
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• 2002

In this paper, we consider a generalized rule of retransmission request, identified as (Μ, $\sigma$) rule for multicopy transmission ARQ. Following a revised rule to conform with a strict criterion for requesting a retransmission, we can reduce the probability that a packet accepted by the receiving node is still being infected with errors. In turn, such amendment invokes a degradation of delay and throughput performance. For a quantitative evaluation of (Μ, $\sigma$) rule, we develop an analytical method to calculate probability of error remains, maximum throughput, average and peak delays, and delay variation. From the numerical examples made by use of the analytical method, we observe a performance trade-off between probability of error remains and delay/throughput. We also confirm the adaptability of (Μ, $\sigma$) rule to meet various QoS requirements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.1
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• pp.79-85
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• 1998

The 9-digit MMSI(Maritime Mobile Service Identity) in the NBDP is converted to the 7-digit identity signal, used to identify to the phase of and to synchronize to the clock of the ISS(Information Sending Station) automatically for phasing procedure between radio stations. In this paper, algorithms for the automatic identification phasing procedures and for conversions, calculations between 7-signals and 9-identity, those check-numbers in the phasing procedures for calling of the NBDP are discussed and designed. And a method of the faster locking and phasing for calling than that of recommended by ITU-R is suggested and implemented.