• The Journal of the Korea Contents Association
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• v.2 no.2
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• pp.73-84
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• 2002

In this paper, we propose a enhanced ERICA switch algorithm using the buffer management scheme which can reduce the queue length, support the efficiency link utilization and the fair share. It has three different buffer thresholds which are low threshold, congestion notification threshold and high threshold. According to the each buffer threshold status, switch announced congestion notification to the source differently. So, sources could know the congestion more quickly and fast remover from network congestion. As a experimental results, it is proved that proposed algorithm is the more efficient than ERICA. Especially, proposed switch algorithm provides congestion control mechanism to make the best use of with keeping fairness and reduce queue length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.29-40
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• 2004

In this paper, we propose a new early congestion detection and notification technique called QR-AQM. Unlike RED and it's variation, QR-AQM measures the total traffic rate from TCP sessions, predicts future network congestion, and determine the packet marking probability based on the measured traffic rate. By incorporating the traffic rate in the decision process of the packet marking probability, QR-AQM is capable of foreseeing future network congestion as well as terminating congestion resolution procedure in much more timely fashion than RED. As a result, simulation results show that QR-AQM maintains the buffer level within a fairly narrow range around a target buffer level that may be selected arbitrarily as a control parameter. Consequently, compared to RED and its variations, QR-AQM is expected to significantly reduce the jitter and delay variance of packets traveling through the buffer while achieving nearly identical link utilization.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.12-19
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• 2005

Reliable transport protocols such as TCP are tuned to Perform well in traditional networks where packet losses occur mainly because of congestion. In a wireless network, however, packet losses will occur more often due to reasons such as the high bit error rate and the handoff rather than due to congestion. When using TCP over wireless network, TCP responds to losses due to the high bit error rate and the handoff by invoking congestion control and avoidance algorithms, resulting in the degraded end-to-end performance in the wireless network. There have been several schemes for improving TCP performance over wireless links. Among them, SNOOP Is a very promising scheme because of the localized retransmission. In this thesis, an efficient scheme is proposed by modifying SNOOP scheme. The invocation of congestion control mechanism is now minimized by knowing the cause of packet loss.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.595-607
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• 2004

Networks often evolve to provide a host with multiple access points to the Internet. In this paper, we propose a transport layer load distribution mechanism utilizing the multiple network interfaces simultaneously. We specifically propose an extension of Stream Control Transmission Protoco1 (SCTP) to have load sharing over multiple network interfaces. We named the particular service provided by the Proposed load sharing mechanism to be LS (Load Sharing) mode service. LS mode service is based on the following four key elements: (i) the separation of flow control and congestion control, (ii) congestion window based striping, (iii) redundant packet retransmission for fast packet loss recovery, (iv) a novel mechanism to keep track of the receiver window size with the SACKS even if they arrive out-of-order. Through simulations, it is shown that the proposed LS mode service can aggregate the bandwidth of multiple paths almost ideally despite of the disparity in their bandwidth. When a path with a delay of 100% greater is utilized as the second path, the throughput is enhanced about 20%.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.311-316
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• 2003

To deploy multicast protocols, fairness to current Internet traffic, particularly TCP, is an important requirement. PGMCC is one of the most promising multicast congestion control proposals but it suffers from degradation of fairness by fixed timeout and uncertain acker selection. In this paper, we suggest addition of an adaptive timeout mechanism and NAK suppression in router using throughput comparison to improve fairness. Our simulation show improved fairness.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.277-278
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• 2015

본 연구는 기존에 제안되었던 혼잡 제어 기법, 그리고 여기에서 고려하지 못한 다종 센서 네트워크 환경을 고려한 혼잡 제어 기법에 대한 연구를 포함한다. 기존의 방법은 대규모 센서 네트워크 또는 특정한 타입의 데이터를 가정하고 혼잡 제어 기법을 제안하였다. 그러나 최근의 센서 네트워크 응용은 다양한 센서의 개발로 그 범위가 확장되는 추세에 있어 다수의 이종 센서 노드가 네트워크 구성 인자로 참여하는 환경이므로 이에 대한 연구가 필요하다. 이에 우리는 기존의 혼잡 제어 메커니즘은 분석하고 이종 센서가 참여하는 센서 네트워크를 고려하는 혼잡 제어 기법을 연구한다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.11
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• pp.25-33
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• 1997

The end-to-end rate-based control mechanism is used for the flow control of the ABR service to allow much more flexibility in ATM switching system. To accommodate the ABR service effciently many algorithms such as EFCI, EPRCA, ERICA, and CAPC2 have been proposed for the switch algorithm. ABR cells and related RM cells are received at the ATM switch fabric transparently without any processing. And then cells received from the traffic source are queued in the ABR buffer of switching system. The ABR buffer usually has some thresholds for easy congestion control signal transmission. Whatever we use, therefore, these can be many ABR traffic control algorithms to implement the ABR transfer capability. The genertion of congestion indicate signal for ABR control algorithms is determined by ABR buffer satus. And ABR buffer status is determined by ABR cells transfer ratio in ATM switch fabrics. In this paper, we presented the functional structures for control of the ABR traffic capability, proposed the readout scheduling, cell slot allocation of output link and the buffer allocation model for effective ABR traffic guranteeing with considering CBR/VBR traffics in ATM switch. Since the proposed readout scheduling scheme can provide more avaliable space to ABR buffer than existing readout scheduling scheme, generation rate of a SEND signal, that is, BCN signal in destination node can be increased for ABR call connection. Therefore, the proposed scheme, in this paper, can be appropriate as algorithm for effective ABR traffic service on output link of ATM switching node.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3502-3509
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• 2010

Streaming service in the wireless mobile network environment has been a very challenging issue due to the dynamic uncertain nature of the channels. Overhead such as congestion, latency, and jitter lead to the problem of performance degradation of an adaptive multi-streaming service. This paper proposes a AMSS (Adaptive Multi-level Streaming Service) mechanism to reduce the performance degradation due to overhead such as variable network bandwidth, mobility and limited resources of the wireless mobile network. The proposed AMSS optimizes streaming services by: 1) use of fuzzy similarity metric, 2) minimization of packet loss due to buffer overflow and resource waste, and 3) minimization of packet loss due to congestion and delay. The simulation result shows that the proposed method has better performance in congestion control and packet loss ratio than the other existing methods of TCP-based method, UDP-based method and VBM-based method. The proposed method showed improvement of 10% in congestion control ratio and 8% in packet loss ratio compared with VBM-based method which is one of the best method.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.131-138
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• 2007

In wired networks, packet losses mostly occur due to congestion. TCP reacts to the congestion by decreasing its congestion window, thus to reduce network utilization. In wireless networks, however, losses may occur due to the high bit-error rate of the transmission medium or due to fading and mobility. Nevertheless, TCP still reacts to packet losses according to its congestion control scheme, thus to reduce the network utilization unnecessarily. This reduction of network utilization causes the performance of TCP to decrease. In this paper, we predict packet loss by using RSS(Received Signal Strengths) on the wireless and suggest adding RSS flag bit in ACK packet of MH. By using RSS flag bit in ACK, the FH(Fixed Host) decides whether it adopt congestion control scheme or not for the maximum throughput. The result of the simulation by NS-2 shows that the proposed mechanism significantly increases sending amount and receiving amount by 40% at maximum.

• Journal of Computing Science and Engineering
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• v.1 no.1
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• pp.31-55
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• 2007

Contemporary end-servers and network-routers rely on traffic shaping to deal with server overload and network congestion. Although such traffic shaping provides a means to mitigate the effects of server overload and network congestion, the lack of cooperation between end-servers and network-routers results in waste of network resources. To remedy this problem, we design, implement, and evaluate NetDraino, a novel mechanism that extends the existing queue-management schemes at routers to exploit the link congestion information at downstream end-servers. Specifically, NetDraino distributes the servers' traffic-shaping rules to the congested routers. The routers can then selectively discard those packets-as early as possible-that overloaded downstream servers will eventually drop, thus saving network resources for forwarding in-transit packets destined for non-overloaded servers. The functionality necessary for servers to distribute these filtering rules to routers is implemented within the Linux iptables and iproute2 architectures. Both of our simulation and experimentation results show that NetDraino significantly improves the overall network throughput with minimal overhead.