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TCP-Friendly Retransmission Persistence Management for SR-ARQ Protocols
HAN, Jechan,KIM, Beomjoon,LEE, Jaiyong The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.10
<P>This letter proposes a new retransmission persistence management scheme for selective repeat automatic repeat request (SR-ARQ). By considering the overall traffic load that has to be managed by SR-ARQ, the proposed scheme arbitrates the retransmission persistence to prevent an abrupt delay increment due to excessive link-level local retransmissions. OPNET simulations show that SR-ARQ performs better with the proposed scheme than with a fixed value of retransmission persistence in terms of the throughput of transmission control protocol (TCP).</P>
Analysis Model for the Transport Delay of NAK-based SR-ARQ with a Finite Retransmission
Jechan Han,Jaiyong Lee 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, we propose a simple analysis model for the transport delay of the negative acknowledgment (NAK)-based selective repeat automatic repeat request (SR-ARQ). We define the transport delay as the time from a packet’s first transmission until its successful arrival at the receiver. By analyzing the transport delay, we can evaluate the efficiency of SR-ARQ’s loss recovery procedures as well as its delay performance. Particularly, the model considers the traffic condition and a finite retransmission persistence of SR-ARQ as well as the packet loss rate over a wireless link. Finally, the analysis model’s accuracy is verified by the simulation results.
Jechan Han(한제찬),Jaiyong Lee(이재용) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.11B
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.
확률론적 지진재해도 분석을 위한 단층지진원의 지진발생율 산정
박제찬(Jechan Park),유현재(Hyun Jae Yoo),한신애(Sinae Han),서경한(Kyunghan Seo),이상선(Sang-Sun Lee) 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
일반적으로 확률론적 지진재해도 분석에는 면적지진원과 단층지진원, 두 가지의 지진원이 사용된다. 면적 지진원의 지진발생률은 지진기록(역사 및 계기지진목록)을 통계분석하여 산정하는 반면, 관련 지진기록이 부족한 단층지진원의 지진발생률은 지질조사를 통해 획득한 단층 정보 및 고지진학적 증거로부터 산정이 가능하다. 지질정보 및 고지진학적 증거로부터 단층의 지진발생률을 산정하는 방법은 두가지가 있다. 하나는 고지진학적 증거와 지진재현모델(earthquake recurrence model)을 활용하는 방법이고, 다른 하나는 단층의 모멘트 평형(moment balancing) 이론과 논리수목(logic tree) 방법을 활용해 지진발생률의 확률분포를 구하는 방법이다. 국내에서 조사된 단층의 지질학적 특성자료를 두 방법에 적용하여 단층지진원의 지진발생률을 산정하고, 그 결과를 비교하여 보았다. 또한, 산출된 지진발생률의 확률분포와 지진재현모델과의 유사성을 분석하여 단층지진원의 주기성을 평가하였다. 이번 연구에서 분석한 단층의 지진발생률 산정 결과는 향후 활동성단층의 확률론적 지진재해도 분석에 활용될 예정이다.
JUNG, Hyunduk,HAN, Jechan,LEE, Jaiyong The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.4
<P>OFDMA femtocells in the macrocellular network of which frequency reuse factor is 1 cause serious interference to macrocell users, while the femtocells improve the performance of indoor users. In this letter, a novel downlink resource allocation algorithm for OFDMA femtocell networks is proposed to reduce interference between the macrocells and the femtocells. This algorithm allocates femtocell subchannels to avoid interference to macrocell users in the femtocell coverage, and minimizes the total transmission power of the femtocell to reduce the negative effect on the performance of the macrocell. Simulation results are provided to present the performance of the proposed algorithm.</P>
Kwang-il Kim,Jechan Han,Jaiyong Lee 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
The recent trend is that the mobile internet service has been offered in the integration of various wireless networks. In such heterogeneous networks, vertical handover is more common and important handover technologies. But during vertical handover, standard TCP has experienced many problems such as multiple packet losses, the packet reordering, the under-utilization due to the drastic change of the Bandwidth Delay Product (BDP) and the network transmission delay (Round Trip Time :RTT). In this paper, we propose “Enhanced TCP congestion control scheme with RTT inflation and the measured-RTT of the new network” for the seamless soft vertical handover and evaluate this by OPNET simulation. We assume the proposed scheme uses the cross-layer design in a TCP receiver and a TCP time-stamp option. OPNET simulation results show that our proposed scheme improves better TCP performance than other handover congestion control schemes such as Freeze-TCP or SSTCP during the vertical handover.
Loss Recovery Modeling of TCP Reno over Wireless Links
Beomjoon Kim,Dongmin Kim,Jechan Han,Jaiyong Lee 에스케이텔레콤 (주) 2003 Telecommunications Review Vol.13 No.5
In this paper, we investigate the loss recovery behavior of TCP Reno over wireless links where packets are not always lost due to network congestion. Loss recovery of TCP Reno operates based on two basic algorithms of fast retransmit and fast recovery. We derive the conditions for successful loss recovery of TCP Reno by modeling the window variation during loss recovery accurately. Based on the developed model, the fast retransmit probability of TCP Reno is derived when the pattern of packet losses are random and correlated. Therefore, the performance of TCP Reno can be evaluated from the aspect of the fast retransmit probability. Main findings of our work are 1) loss recovery function of TCP Reno is not effective when multiple packets are lost in a window. 2) Continuity of packet losses as well as packet loss probability can affect the fast retransmit probability. We explain some of these observations in terms of the variation of the average window size and packet loss probability.