• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.787-793
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• 2015

In order to support reliable medium access control (MAC) layer multicast services in Broadband Wireless Access (BWA) networks, we here propose spreading codes (Cumulative ACK (CA) code and ARQ Feedback Request (AFR) code) based reliable multicast feedback scheme. The status indications based on the automatic repeat request (ARQ) mechanism are needed in some multicast services. In accordance with various wireless channel environments, we demonstrate the performance excellency of our proposed scheme with respect to required uplink resources compared with the original feedback scheme based on unicast ARQ feedback messages. In addition, we analyze packet error rate (PER) against the various wireless channel environments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.894-897
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• 2008

This paper analyzes the throughput performance of a selective repeat (SR)/automatic repeat request (ARQ) scheme to transmit packet data in burst home network channel. To combat the high degree of error caused by transmission of home network data a robust error control scheme is a necessity. Basically, error control schemes can be divided in two categories: ARQ schemes and forward error correction (FEC) schemes. ARQ schemes are often used for reliable data transmission. The performance of packet transmission using SR-ARQ schemes for bursty channels is analyzed and simple analytical expressions of its throughput are presented. Theoretic analysis and numerical results indicate that a small number of packet sizes can get good performance in bursty home network channel.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.199-205
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• 2012

This work investigates the progressive linear precoder design for packet retransmissions in multi-input multi-output (MIMO) systems with multiple codewords and automatic repeat request (ARQ) bundling feedback. Assuming perfect channel state information, a novel progressive linear ARQ precoder is proposed in the perspective of minimizing the packet error rate. We devise the ARQ precoder by combining power loading and sub channel pairing between current retransmission and previous transmissions. Furthermore, we extend the design to the case that the channel estimation error exists. Numerical results show that the proposed scheme can improve the performance of MIMO ARQ systems significantly regardless of the channel estimation error.

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.86-91
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• 2011

In the underwater communications, the acoustic channel is in poor communication conditions, such as long propagation delay, narrow bandwidth, and high bit-error rate. For these bad acoustic channels, we propose an efficient automatic repeat request (ARQ) for multi-hop underwater network by using the concepts of concurrent bi-directional transmission, multiple sub-packets, and overhearing data packet instead of the acknowledgement signal. Our results show that the proposed ARQ significantly reduces the transmission latency especially in high BER compared with the existing Stop and Wait ARQ.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.451-458
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• 2010

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.9-12
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• 2007

In this paper, we propose and analyze a scheme for wireless channels, which is a combination of a type I hybrid-automatic repeat request (H-ARQ) scheme and a power ramping. The power ramping is considered for more reliable downlink data transmission, in which the transmission power is gradually changed from a small level to a large level when the number of retransmissions increases. The simulation results demonstrate that, when the power ramping step size is 0.5dB, the average throughput gain may be as high as 2% to 5% with properly selected parameters.

• The KIPS Transactions:PartC
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• v.15C no.6
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• pp.523-530
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• 2008

In this paper, we analyze the mean queuing delay of selective-repeat automatic repeat request (SR-ARQ) protocol with the finite retransmission persistence. The retransmission persistence means the willingness of the protocol to retransmit a lost (or corrupted) packet to ensure reliable packet delivery across a lossy link. According to the retransmission persistence, SR-ARQ protocols have a different performance in terms of both packet delay and link reliability. So far, however, there is no serious study in the effect of the retransmission persistence on the SR-ARQ performance. We present a simple M/G/1 queuing model for the SR-ARQ protocol with the finite retransmission persistence by using the ideal SR-ARQ approximation. The mean queuing delay is obtained from the queuing model and verified its accuracy through the simulation results using the OPNET simulator. Both the analytical predictions and simulation results clearly show the effect of retransmission persistence on the queuing delay of the SR-ARQ protocol in various network conditions: packet loss rate and traffic condition over a wireless link.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.581-584
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• 2003

본 논문에서는 링크 상황에 따라서 변복조 방식과 코딩 방식을 달리하는 기술인 AMC(Adaptive Modulation and Coding)기능과 연동하는 2 단계 ARQ(Automatic Repeat Request)방식을 제안하여 한정된 무선채널을 여러 종류의 서비스와 여러 가입자가 동시에 공유하는 경우에 발생되는 QoS(Quality of Service) 문제를 해결하고자 한다. 제안한 2 단계 ARQ 방식은 MAC(Medium Access Control) 계층에 위치하여 상위 계층으로부터 IP(Internet Protocol) packet 를 수신한 후 2 단계의 ARQ 동작을 수행함으로써 물리 채널에서 전송 중에 발생되는 오류 확률을 감소시킨다. 따라서 TCP(Transmission Control Protocol)단에서의 재전송 감소에 의한 향상된 성능도 기대할 수가 있겠다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.989-997
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• 2008

The reverse acknowledgment (RA) scheme supports a fast loss recovery for negative acknowledgment (NAK)-based selective repeat automatic repeat request (SR-ARQ) by detecting a retransmission failure quickly before a retransmission timer expires. In this paper, we evaluate the performance of a NAK-based SR-ARQ protocol with the RA scheme and compare it with the conventional NAK-based SR-ARQ protocol. Particularly, we propose a simple analysis model for the transport delay of the NAK-based SR-ARQ protocol considering the traffic condition, the retransmission persistence, the timer-based retransmissions and the RA scheme's behavior. Both NAK-based SR-ARQ protocols with and without the RA scheme are implemented by using the OPNET simulator. We verified the analysis model's accuracy through the simulation results. Also, we evaluate the performance of the NAK-based SR-ARQ protocol with the RA scheme based on analysis and simulation results.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.4
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• pp.487-492
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• 2011

This paper proposes a retransmission persistence control scheme for automatic retransmit request (ARQ) protocol to improve the reliability of a wireless link. Most existing ARQ protocols adopt a fixed retransmission persistence. If the ARQ protocol sets the retransmission persistence too low, there is a limitation in providing transmission reliability. On the other hand, if the ARQ protocol sets the retransmission persistence too high, it increases transmission delay and jitter. In order to figure out the problem, the proposed scheme considers the number of frames in the buffer in controlling the retransmission persistence; it improves the throughput of ARQ protocol by increasing the retransmission persistence when the number of frames is small and decreasing otherwise. Simulation results show that the proposed scheme decreases the transmission delay and jitter significantly comparing to the existing schemes.