• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.134-146
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• 2005

Research about QoS in the ad-hoc networks for stable service of various applications has been needed as the expectation about the realization of the ad-hoc networks grows bigger. Existing researches about QoS in the ad-hoc network had the problems which can not guarantee the quantitative services or create the overhead. In this paper, we propose a novel algorithm of QFAN(QoS Framework for Ad-hoc Networks) the framework to resolve such problems and considered application of the proposed algorithm into the ad-hoc networks. Our model can guarantee the minimum bandwidth of the real-time traffic as minimized the overhead. And, disproportionate distribution of bandwidth problem can resolve by the proposed algorithm through the fair share between real-time traffic and best-effort traffic about available bandwidth. We design both the TiRe(Tiny Reservation) and the ADR(Adaptive Drop Rate) control algorithm to apply the proposed QFAN. Using simulation, we confirm fair share of available bandwidth between real-time traffic and best-effort traffic as guarantee minimum required bandwidth of real-time traffic.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.469-471
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• 2005

최근 인터넷에서는 인터넷 방송, 화상 회의, VoIP 등 QoS 보장을 요구하는 새로운 응용 서비스들의 출현과 함께 IP QoS의 문제는 인터넷에서 가장 주요한 과제 중 하나로 등장하고 있다. 이러한 QoS의 적용은 가장 상용화 되어 있는 이더넷 망에서도 마찬가지로 적용되어야 하는 문제이다. 또한 사용자들은 SLA(Sonics Level Agreement)내에서 최선의 QoS 요구하게 되었다. QoS 보장을 위해 기존에는 통합 서비스(Integrated Service)나 차별화 서비스(Differentiated Service) 방식만을 사용하였으나 실제 적용하는데 구현상의 여러 문제점이 발견되었고, 대역폭 할당 방식에 있어서도 토큰 버킷(Token Bucket)과 같은 복잡한 방식을 사용하였다. 본 논문에서는 간단하면서 적용하기 쉬운 QoS 보장을 위한 멀티큐에서의 속도 계산(Rate Calculation)방식을 제안하며 OPNET을 통해 제안된 방식을 검증하도록 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.484-486
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• 2002

주문형 비디오 서비스(VoD: Video on Demand)의 경우 네트워크의 자원 이용도와QoS (Quality of Service)가 보장되도록 구축되어야 한다. 대역폭 스무딩 알고리즘은 주문형 비디오 시스템에서 비디오 데이터를 보낼 경우 비디오의 데이터의 급격한 대역폭의 증가 또는 감소를 최소한 줄이는 기법이다. 본 논문에서는 기존의 대역폭 스무딩 기법과 비디오 압축 기법의 특성을 이용하여 새로운 모델과 스무딩 알고리즘을 제안한다. 제안된 알고리즘의 성능평가를 위해 기존 스무딩 알고리즘의 결과와 비교 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4C
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• pp.308-315
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• 2002

Guaranteed frame rate (GFR) service has been defied to provide minimum cell rate (MCR) guarantees for virtual connections (VCs) carrying Internet traffic in ATM networks and allow them to fairly share residual bandwidth. The simplest switch implementation mechanism to support the GFR service in ATM networks consists of the frame-based generic cell rate algorithm (F-GCRA) frame classifier and the early packet discard (EPD)-like buffer acceptance algorithm in a single FIFO buffer. This mechanism is simple, but has foiled to guarantee the same bandwidth as an MCR to a VC that has reserved a relatively large MCR. This paper applies the packet spacing scheme to TCP traffic to alleviate its burstness, so as to guarantee a larger MCR to a VC. In addition, the random early detection (RED) scheme is added to the buffer acceptance algorithm in order to improve fairness in use of residual bandwidth. Simulation results show that the applied two schemes improve a quality of service (QoS) in the GFR service for the TCP traffic.

• Journal of Digital Contents Society
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• v.2 no.2
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• pp.129-138
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• 2001

With the explosive growth and pervasive of the Internet, dynamic bandwidth allocation is nessary for ATM streams that carry various traffic. In order to provide quality of service(QoS) guarantees and to give the minimum cell rate, new bandwidth allocation scheme requires to be implemented. DFBA(Differential Fair Buffer Allocation) scheme is one of the methods for ATM GFR(Guaranteed Frame Rate) services. DFBA scheme treats cells selectively in a region between low buffer occupancy threshold and high buffer occupancy threshold. A big unbalance is introduced when the value being selected by DFBA scheme is greater than minimum rate. In a try to reduce the unbalance modified DFBA scheme is proposed. Selecting parameter according to the situation of network, this scheme is very effective to control the bandwidth in the various network situation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.811-817
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• 2005

Efficient bandwidth management is necessary in order to provide high quality service to users in a multimedia wireless/mobile network. In this paper, I propose an on-line load balancing algorithm with preemption. This technique is able to balance the traffic load among cells accommodating heterogeneous multimedia services while ensuring efficient bandwidth utilization. The most important features of my algorithm are its adaptability, flexibility and responsiveness to current network conditions. In addition, my online scheme to control bandwidth adaptively is a cell-oriented approach. This approach has low complexity making it practical for real cellular networks. Simulation results indicate the superior performance of my algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1351-1354
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• 2001

본 논문에서는 Differentiated Services (DiffServ) 망의 edge 라우터에 적용되는 3 단계 트래픽 제어기 (3 phased traffic conditioner : 3PTC)를 제안하였다. 제안된 3PTC 는 TCP 트래픽의 예약된 대역폭 (reserved rate) 의 차이, UDP/TCP의 상호작용, RTT 및 집합된 트래픽을 구성하는 작은 트래픽 수에 의한 영향을 최소화함으로써, DiffServ 망에서 제공하는 Assured Services 사용자들에게 공정한 대역폭을 보장해 줄 수 있다. 3PTC 는 토큰버킷 단계, 확률결정 단계, 그리고 버퍼관리 단계로 이루어져 있다.

• Journal of KIISE:Information Networking
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• v.28 no.2
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• pp.242-250
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• 2001

This paper deals with the TCP bandwidth guarantee problem in a differentiated serviccs(Diffserv) network. The Diffserv assured s<:rvice differentiates packet drop probabilities to guarantee the promised bandwidth even under network congestion. However a token buffer marker fails to show adequate performance because TCI' generates packets according to the unique Tel' congestion control mechanism. We propose a marker that uses a data buffer as well as a token buffer. The marker with a data buffer works well with the assured service mechanism because it smooths Tel' traffic. We showed that the marker with a data buffer achieves the target throughput better than a marker with a token buffer only. We also showed that the optimal buffer size is proportional to reserved throughput and HTT.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.997-1006
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• 2008

SVP-capable router supporting guaranteed services on the internet generally uses a packet scheduler based on the Weighted Fair Queuing(WFQ) algorithm to secure required qualities of traffic flows. In this paper we proposed a RSVP-capable router based on the LOFQ(Latency optimized fair queuing) algorithm that improves the efficiency in bandwidth utilization with keeping the compatibility with the original RSVP procedure. The proposed router reserves the optimal amount of resource for each flow to secure its required quality-of-service with the recently introduced LOFQ scheduler. The results of the simulation applying the proposed router to an evaluation network showed that it may yield the gain of up to 30% compared to that in the original one in terms of the number of admitted flows.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.386-390
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• 2004

유무선 혼합 망에서 GFR서비스의 최소대역, 효율 및 트래픽 제어를 위한 버퍼관리 기법 등을 유무선 혼합망의 셀기반 네트워크에서 가중치를 높이는 시뮬레이션을 통해 공평성을 입증하는 연구를 한다. GFR서비스는 TCP/IP 패킷의 품질보장과 베스트 에포트 트래픽에 대한 최소의 대역폭 보장을 하며, 가용 대역폭에 대한 공평성 있는 대역할당을 지원해야 하기 때문에 버퍼관리를 통한 셀 폐기와 셀 스케줄링 둥이 중요한 요소이다. 본 논문에서는 유무선 혼합 네트워크에서 MCR을 보장하기 위하여 버퍼의 사용 가능한 영역의 활성 VC에 각 VC가중치를 비례해 할당하는 per-VC 어카운트에 기초한 트래픽 제어의 버퍼관리에 대한 유동적 WBA알고리즘을 제안하고 GFR 서비스의 효율 및 공평성을 유무선 혼합 망 셀 기반의 스위치를 이용하여 시뮬레이션으로 결과를 보인다.