• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1616-1623
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• 1999

This paper describes error resilient coding scheme is added in WLL system and its application for robust low-bit rate still image transmission over power controlled W-CDA system Rayleigh fading channels. The baseline JPEG compressing methods are uses in image coding over wireless channel. The channel uses Reed-Solomon(RS) outer codes concatenated with convolutional inner codes, and truncated type I hybrid ARQ protocol based on the selective repeat strategy and the RS error detection capability. Simulation results are proved for the statistics of the frame-error bursts of the proposed system in comparison with conventional WLL system. it gains the 2 dB of the Eb/No in same BER.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.288-298
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• 2003

We consider a window-controlled selective-repeat ARQ scheme for error control between two adjacent nodes lying on a communication path. In this scheme, each packet to be transmitted is endowed with a serial number in a cyclic and sequential fashion. In turn, the transmitting node is not allowed to transmit a packet belonging to a window before every packet in the previous window is positively acknowledged. Such postponement of packet transmission incurs a degradation in throughput and delay performance. In this paper, aiming at improving packet delay performance, we employs a supplement scheme in which a serial number is duplicated within a frame. Classifying duplication rules into fixed, random and adaptive categories, we present candidate rules in each category and evaluate the packet delay performance induced by each duplication rule. From numerical examples, we observe that duplicating serial numbers, especially ADR-T2 effectively reduces mean packet delay for the forward channel characterized by a low packet error rate. We also reveal that such delay enhancement is achieved by a high probability of hitting local optimal window size.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1994.06a
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• pp.468-473
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• 1994

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.199-202
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• 1988

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.557-560
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• 1996

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.160-160
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• 1991

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.1
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• pp.16-22
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• 2012

Wireless data communication is easy to be affected by channel noise and degrade reliability and stability by the multipath fading and ISI compared with wired data communication. In this paper, we designed and implemented indoor wireless modem adopted DQPSK modulation scheme for improvement of bandwidth efficiency, and convolutional encoding, Viterbi decoding and hybrid ARQ algorithm combinig FEC with CRC for efficient error control in indoor wireless channel. Testing the implemented wireless modem, we verified the proposed scheme is proper to efficient and reliable indoor wireless data communication.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.11-18
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• 1995

Error detection in ARQ(Automatic Repeat Request) protocols is very important in wireless data communication systems. The throughput efficiency of ARQ protocols can be improved by dynamically adapting the protocol packet length so that it approaches the optimum value for throuhput efficiency. In this paper, a simple and novel adaptive packet length allocation method is proposed which transmits the packets with variable length by dyanmically estimating the channel codition. The simulation results show that the average of throughput is improved by 315.4% in the stop-and-wait protocol, 41.4% in the go-back-N protocol and 155.9% in the selective repeat protocol respectively. And the throughput performances of adaptive packet length allocation method approximately approach the theoritically optimal throughput performances.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.301-306
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• 2005

In this paper, we propose P-SRA (Proposed Simplified Resource Allocation) algorithm for efficient resource allocation for real time traffic in MIMO-OFDMA (Multiple Input Multiple Output - Orthogonal Frequency Division Multiple Access) systems with V-BLAST (Vertical-Bell laboratories LAyered Space-Time coding) detector. The proposed P-SRA scheme employs efficient 3 step resource allocation algorithm with plain V-BLAST and no H-ARQ, however it achieves comparable performance of a MIMO-OFDMA system utilizing error compensated V-BLAST and H-ARQ IR scheme.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.644-648
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• 2002

멀티미디어 서비스를 제공하는 미래의 이동통신 시스템에서는 데이터의 신뢰성 있는 전송을 위해 데이터링크 계층에서 제공하는 프레임 에러율(FER: Frame Error Rates)을 감소시켜야 한다. 이를 위해 라디오링크 프로토콜(RLP: radio link protocol) 계층에서는 ARQ(Automatic Repeat request) 기법을 사용한다. 본 논문에서는 기지국에서 이동 호스트로 전송되는 국부적인 재전송 프레임(Frame)의 순서가 연속된 에러로 인하여 순서가 뒤바뀌고, 이로 인하여 기지국 데이터 링크계층에서 잦은 재전송으로 발생되는 높은 상호지연을 줄이기 위해 개선된 비순서적 재전송 기법을 제안하였다. 제안된 기법은 재전송방법 중 선택적 거절(selective-reject) ARQ의 비순서적 재전송에 수정한 빠른 재전승 기법을 적용하였으며, 기지국과 이동호스트 사이에서 데이터그램(Datagram)의 단편화(fragment)로 인한 링크계층의 Re-Sequencing을 하지 않기 때문에, 종단간 지연된 성능을 향상 시킬 수 있다.