• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1285-1294
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• 1999

In this paper we consider the performance of TCP video traffic over ABR with Long-Range Dependent VBR traffic. As compressed coded video traffics are increasing rapidly over Internet, lots of studies are being done for transmitting those traffics efficiently using limited network resources. We consider here the transmitting video service over ABR service in ATM networks, especially satellite networks. CBR or VBR services are suggested in transmitting the video traffic in ATM Forum TM 4.0. But ABR service connection, which is considered as appropriate service for data traffic, can be established with a small amount of bandwidth, MCR (Minimum cell rate). Furthermore ABR service can control the source's transmitting rate using feedback mechanism. Using this feature ABR service can be used in some applications which can control their quality of services corresponding to network loads. Compressed video sources with MPEG-2 are used for Long-Range Dependent VBR traffic here. We model the compressed video source to resemble the MPEG-2 transport streams. These compressed video traffic streams are consisted of three different frames, I-frame, P-frame, and B-frame. So when a network are overloaded, we can control the quality of service using this traffic features. TCP Traffics over ABR need large buffers in ATM switch to satisfy their QoS with background VBR traffics, which have high deviations in bandwidth. Furthermore satellite ATM networks with large feedback delay need large buffers corresponding RTT delay. The performance comparisons among EFCI and ER switch (ERICA+) switches in the network circumstances described above were shown in this paper. We also considered the case with ON-OFF VBR traffics.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.85-88
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• 2000

장거리 링크를 가지는 ATM 망에서는 긴 전파지연의 영향을 고려하여 설정된 가상종단시스템을 이용하여 ABR 서비스를 제공해야 한다. 본 논문에서는 가상종단시스템을 이용하여 ABR 서비스를 제공하는 데에 필요한 조건인 많은 개수의 가상연결들에 대한 ABR 서비스 제어 기능을 설계하기 위한 제반 고려 사항들을 살펴보고 구현을 위한 설계 구조를 제시하였다. 제시한 설계 구조에서는 많은 개수의 가상연결들에 대해 ABR 서비스를 수용해 줄 수 있도록 공유 메모리 구조를 이용한 셀 송출 제어 구조를 적용하였다.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.98-104
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• 2000

One of the main features of ABR service is the employment of a rate-based flow control mechanism, and congestion control plays an important role in the effective and stable operation of ATM networks Feedback from the network switches to the end system gives users the information necessary to adjust transmission rates appropriately according to the current networks load. Congestion controls by feedback mechanism are classified as EFCI and ER mode. We analyze the performance of EFCI and ER and propose a new ABR traffic control strategy by integrating EFCI and ER modes to improve the traditional traffic control. Through the distributed simulation. the performance improved by the proposed control strategy is analyzed.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.527-539
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• 2001

The wireless asynchronous transfer mode (ATM) system has the advantage of providing the broadband services with various quality-of-service requirements to the mobile terminal efficiently by utilizing the ATM technology developed for the wired ATM system. The available bit rate (ABR) service among various ATM services utilizes the available bandwidth remaining in the ATM link, which allows the efficient bandwidth usage. During the handoff of the mobile terminal, however, the queue length in the access point (AP) which resides in the boundary of the wired ATM network and the wireless ATM network may increase abruptly. In this paper, we propose a scheme which prevents the buffer-overflow and buffer-underflow in the AP during the handoff of the wireless ABR connection in the wireless ATM system using binary feedback rate-based ABR traffic control. This scheme controls the source's cell generation rate during both handoff period and some time interval after the completion of the handoff procedure. The simulation results show that the proposed scheme prevents the buffer-overflow and buffer-underflow. The proposed scheme can contribute to increasing the throughput of the wireless ABR service during handoff by preventing the buffer overflow and underflow during handoff period.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.28-34
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• 1998

In ATM networks CBR data traffic is sent in constant bit rate, and VBR data traffic in variable bit rate. Therefore unused bandwidth at network capacity may exist. To avoid waste of network resourcesm, ABR traffic utilizes the unused bandwidth to the utmost after CBR and VBR data traffic being first served. In this paper, a transfer rate-based congestion control algorithm is proposed for efficient ABR service in ATM networks. In the proposed algorithm the ATM switch first calculates bandwidth according to variable cell transfer rate in an ABR source. records this value in ER field in a RM cell, and then transmits a RM Cell to an ABR source. In this way the proposed algorithm dynamically allocates bandwidth to each ABR source, and the switch also can rapidly adapt to a change of a transfer rate of an source. The performance simulation of the proposed algorithm has batter performance in terms of source condition and link utilization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.313-322
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• 2000

The ATM Forum has been focusing on flow control mechanism for ABR traffic management. The goal of this activity is to efficiently manage the leftover network bandwidth and fairly distribute it among contending ABR VC so that communication links can be optimally utilized. ABR traffic is difficult to predict traffic shape because it has bursts and variable behavior. Also it's sensitive to lose but not to delay. This behavior makes difficult to UPC function in network and cause of congestion in switch, thus performance is degraded. To resolve this problem, various flow control mechanism has been worked in the ATM Forum. Especially, the rate-based flow control mechanism for ABR traffic has been standardized in the ATM Forum, Sept. 1994. Thus, various flow control mechanism has been working which likes EFCI, ER, VS/VD. VS/VD control is superior than existed ER control because it isolate different networks from each other. In this paper, we propose an expanded VS/VD flow control algorithm and compare with existed VS/VD flow control algorithm. Simulation result shows that this algorithm improve a problem in aspect of delay and fairness.

• Review of KIISC
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• v.8 no.1
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• pp.99-112
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• 1998

ATM 방식을 근간으로 한 광대역 통신망의 급속한 발전에 따라 점차로 그 수요가 증가할 데이터 응용들을 위한 ABR서비스는 우선 순위가 높은 다른 서비스들이 이용하고 남는 가용 대역폭을 최대한 활용해야 한다. 따라서 최근까지도 피드백을 이용한 대응적 제어를 이용한 폭주 제어 방식들에 대한 연구가 진행되어왔고 여러 알고리즘들이 제안되었다. 본 논문에서는 ATM망에서의 ABR(Available Bie-Rate) 트래픽의 특성과 ATM포럼과 ITU-T등에서 표준화되었거나 현재 연구중인 다양한 제어 기법들에 대한 개괄적인 분석이 수행되었다. 그와 아울러 각 알고리즘들의 장, 단점을 살펴보고 개선되어야 할 사항들을 제시하였으며 좀 더 효듈적인 제어를 위해 고려되어야 할 트래픽 특성들을 설명하고 있다.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.95-98
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• 1998

In this paper, we propose a cell scheduling algorithm for ABR traffic in ATM multiplexer. Proposed Algorithm can support ABR service more efficiently than existing WRR and DWRR algorithm. We evaluate the performances of proposed algorithm through computer simulation. Also, we model the VBR and the ABR traffics as ON/OFF source, and the CBR traffic as a Poisson source. And the simulation shows that proposed algorithm better performance over other cell scheduling algorithm in tem of mean cell delay time.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.927-936
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• 1995

ATM Forum has defined a new service class for data applications called Available Bit Rate(ABR) Service, which has highly bursty traffic and unpredictable burst size. It is desirable that we reduce the probability of retrans mission of packets by minimizing the loss of cells because the traffic is much more sensitive to loss than delay. The Forum has also selected the Rate-Based Control for the ABR service and proposed EPRCA as the control mechanism for the service. This paper proposes the combination of EPRCA and the other feedb ack control mechanisms such as BECN and BP. The combined control mechanism control ABR traffic more efficiently and the simulation results show that the network performance can be improved by choosing the appropriate parameters.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2605-2614
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• 1997

Recently, we are concerned with effective service according as the demand increase for high speed data service. We can use high speed transfer and multiple traffic service on the ATM networks, so we concentrate on preventive-control method rather than reactive-control one. But it is possible to have low QoS and traffic congestion due to unpredictable traffic and burst traffic. Specially, ATM Forum has discussed to standardization of traffic management of ABR(Available Bit Rate) service. Because ABR traffic controls the flow of traffic using the feedback information and the current status information of cell, it allocates bandwidth systematically and dynamically to the user. In this paper, we propose a new Rate-based flow control scheme which adapted double threshold buffer idea. The double threshold buffer controls the traffic control by establishing two threshold in buffer.