• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.31-33
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• 2003

현재 국외에서는 산업계 및 학계를 중심으로 기존의 IPv4와 연동 가능한 IPv6에 대한 연구를 추진하고 있다. 또한 국내에서도 IETF의 표준화 기술을 중심으로 몇몇 기관에서 고정망 중심의 IPv6 전이 메커니즘을 구현하고 있다. 그러나 연동 기술에 대한 연구가 고정망에 중심을 두고 있어 이동망에서의 연동 구조에 대한 연구는 부족한 현실이다. 이와 같이 국내외적으로 IPv6망에서의 이중 스택 구조는 고정망을 기반으로 연구가 진행되고 있지만, 이동 인터넷 환경에서의 전이 메커니즘에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 이동 인터넷 환경에서의 전이 메커니즘에 대한 시나리오 제안과 요구사항 분석을 하고, 절기서 제안된 메커니즘들 중 6to4에 이동성을 적응했을 때의 성능 측정 결과를 제시한다

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.733-735
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• 2001

본 논문에서는 Ad hoc 망에서 오류 발생률에 적응적인 LLC와 MAC 프로토콜은 설계하였다. 이 프로토콜은 무선 링크상에서 수신자의 피드백 정보에 의존한다. LLC 계층에서는 피드백 정보에 따라 적합한 FEC를 선택하여 부호화하고 MAC 계층에서는 이를 뒷받침하기 위해 오류 발생 패킷에 대한 새로운 재전송 메커니즘을 사용한다. 결과적으로 시간에 따라 변화하는 채널 환경에 적응하여 성공적으로 패킷을 전송함으로써 패킷 전달 지연시간을 단축시키고 제한된 채널의 대역폭을 효과적으로 사용한다.

• The Transactions of the Korea Information Processing Society
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• v.13 no.10
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• pp.475-480
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• 2024

As Internet of Things (IoT) technology is being used in all industries, the importance of secure and convenient firmware update technology is increasing. However, conventional FOTA (Firmware Over-The-Air) technology has a problem because the security is weak when updating firmware with a single path, and strong encryption technology cannot be utilized. Therefore, this study proposes a secure FOTA (S-FOTA) mechanism for lightweight IoT and adaptive S-FOTA ARQ (Automatic Repeat Request) mechanism. This adaptive S-FOTA ARQ mechanism considers the case where the original file cannot be recovered because of the increase in lost files due to the congested channel state and compares and analyzes the conventional method in terms of security, complexity, and transmission speed. Experimental results show that S-FOTA with 40 encrypted files reduced the attacker's attack success rate by at least 62.58% and up to 99.99%, and S-FOTA with 40% of the total number of encrypted file segments takes at least 996.39% more time on average and up to 3374.99% more time than conventional FOTA. In addition, the transmission speed of the adaptive S-FOTA ARQ mechanism was at least 63.16% and up to 2736.36% higher than that of the conventional S-FOTA, and at least 53.89% and up to 70.89% higher than that of the conventional ARQ mechanism.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1099-1104
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• 2020

In order to provide various types of application services based on the Internet, it is ideal to guarantee the quality of service(QoS) for each flow. However, realizing these ideas is not an easy task.. It is effective to classify multiple flows having the same or similar service quality requirements into same group, and to provide service quality for each group. The queue management mechanism in the router plays a very important role in order to efficiently transmit data and to support differentiated quality of service for each service. In order to efficiently support various multimedia services, an intelligent and adaptive queue management mechanism is required. This paper proposes an intelligent queue management mechanism based on deep reinforcement learning that decides whether to deliver packets for each group based on the traffic information of each flow group flowing in for a certain period of time and the current network state information.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.1-14
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• 2002

The most important issue in providing multimedia traffic on a mobile computing environments is to guarantee the mobile host(client) with consistent QoS(Quality of Service). However, the QoS negotiated between the client and network in one cell may not be honored due to client mobility, causing hand-offs between cells. In this paper, a call admission control mechanism is proposed to provide consistent QoS guarantees for multimedia traffics in a mobile computing environment. Each cell can reserve fractional bandwidths for hand-off calls to its adjacent cells. It is important to determine the right amount of reserved bandwidth for hand-off calls because the blocking probability of new calls may increase if the amount of reserved bandwidth is more than necessary. An adaptive bandwidth reservation based on an MPP(Mobility Pattern Profile) and a 2-tier cell structure has been proposed to determine the amount of bandwidth to be reserved in the cell and to control dynamically its amount based on its network condition. We also propose a call admission control based on this bandwidth reservation and "next-cell prediction" scheme using an MPP. In order to evaluate the performance of our call admission control mechanism, we measure the metrics such as the blocking probability of our call admission control mechanism, we measure the metrics such as the blocking probability of new calls, dropping probability of hand-off calls, and bandwidth utilization. The simulation results show that the performance of our mechanism is superior to that of the existing mechanisms such as NR-CAT1, FR-CAT1, and AR-CAT1.

• Annual Conference of KIPS
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• 2006.05a
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• pp.1283-1286
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• 2006

본 논문에서는 관찰된 채널의 유휴 시간을 이용하여, ACK(Acknowledgement) 기반의 링크 적응 기술의 단점을 극복하는 새로운 알고리즘인 COLA 를 제안한다. COLA 는 광범위한 채널과 부하 상황에서 최적의 성능을 얻으며 RTS/CTS 메커니즘이나 하드웨어를 이용한 채널 SNR 측정과 같은 추가적인 옵션 혹은 별도의 프로토콜 메커니즘의 지원이 필요하지 않다. 또한 COLA 알고리즘은 단지 짧은 10 개의 critical 한 명령어를 사용함으로써 부하를 줄이며, 실제 동작 시 수반되는 heuristic 한 매개변수로부터 자유롭고, 따라서 실제 사용 시 장점을 가진다.

• Annual Conference of KIPS
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• 2005.05a
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• pp.1683-1686
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• 2005

사용자 위치 정보를 보호하기 위해서는 암호화 작업이 필수적이며, 최근 위치 정보 기반 어플리케이션에 적용하기 위한 방안이 커다란 논점으로 자리잡고 있다. 그러나 데이터 암호화 작업은 일정한 시간을 소요하는 작업이므로, 이에 따른 시스템 운용에 있어서 속도와 보안 사이의 균형 문제가 야기 된다. 따라서 본 논문에서는 성능 측면에서 대립되는 속도와 보안 관련 문제를 통제할 수 있는 사용자 위치 정보 관리 메커니즘을 설계하였다. 이를 위해, 그 동안 연구되었던 각종 암호화 알고리즘에 대한 성능 분석과 함께 위치 정보에 대한 분류 작업을 수행하였으며, 해당 연구 결과를 토대로 하여 사용자 위치 정보 관리 메커니즘을 설계하였다. 따라서 본 메커니즘은 다변화하는 주변 환경에 적응적으로 대처하여 시스템의 성능을 항상 최적화할 수 있도록 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.983-989
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• 2012

IEEE 802.3az LPI mechanism allows an Ethernet link to reduce power consumption by entering a low-power sleeping mode and letting some components being powered off when there is no data to be transmitted through the link. However, if small amount of packets are being sent periodically, such a mechanism can not obtain energy efficiency due to a high overhead caused by excessive mode transitions. In this paper, we propose an enhanced LPI mechanism which can perform state transition adaptively based on the traffic characteristics on transport layer and network status. This simulation result shows that proposed mechanism improves energy efficiency than LPI mechanism with respect to energy consumption rate for various traffic loads.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.221-226
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• 2002

Cycling Packet Dropping mechanism we proposed in this paper adaptively drops packets, as predicting traffic pattern between each cycle. Therfore the proposed mechanism makes up for the drawback of RIO mechanism and minimizes errors being capable of predicting in Dynamic and Strict Packet Dropping mechanism. And we executed a simulation and analyzed the throughput and packet drop rate based on the Sending Drop Precedence changing dynamically depending on the network traffic. The results show that the proposed mechanism provides better performance on drop precedence levels and stricter drop precedence policy for AF class.