• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.820-827
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• 2010

In these days, video applications for special purposes such as video conference systems among multiple users and video surveillance systems require multiple video connections and QoS guarantee. The video systems employ IEEE 802.11 Wireless LAN devices to support broadband wireless interfaces and easy internet accesses for cheaper prices. However, according to the current IEEE 802.11e HCCA standard, if more than three video sessions are established in WSTA services, some of them must share the TXOP because the available number of TSIDs for video transmission is two. In order to resolve the problem, we devised a method which can establish up to 15 video sessions by slightly modifying the frame structure while maintaining the compatibility with current standard. Our method is implemented on the NCTUns 4.0 network simulator, and evaluated not only numerically in terms of throughput, delay, and PSNR, but also experimentally in the sense of real video clips that are used as input to our simulation. The results showed that our method sufficiently guarantees the transmission bandwidth requested by each video session.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.817-826
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• 2005

BcN(Broadband convergence Network) is being developed in order to support a variety of network applications, with enhanced capabilities of QoS(Quality of Service) provisioning and security, and IPv6. In a high-speed network environment such as BcN, it if more likely for the network resources to be exposed to various intrusion activities. The propagation speed of intrusion is alto expected to be much faster than in the existing Internet In this paper, we present a multi-domain security management framework which my be used for a global intrusion detection at multiple domains of BcN and describe its characteristics. For the performance evaluation, we first present test results for the security node and compare with other products. Then we design and Implement an OPNET simulator for the proposed framework, and present some simulation results. In the simulation model, we focus on the performance of alert information in the security overlay network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5140-5147
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• 2013

This paper presents a new idea of structural design of the optical access network for IPOW(IP over WDM) services. More efficient network can be constructed, because the IP packets are transmitted directly to the WDM without going through an intermediate layer of networks. The wavelength Routing is based on a label switching technology. The ability to transmission of high volume traffics and QoS capability of the optical label switching directly to the end user of the IPOW optical internet networks is provided. As in AON(Active Optical Network) flexible bandwidth on demand subscribers is allocated. By the Simulation of the proposed optical access networks to measure the BER(Bits Error Ratio) at the end of the nodes the network characteristics are analyzed. These results are based on the design of efficient optical network.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.38-49
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• 2006

In order to increase the spectrum efficiency, recently, there is the number of studies for CR technology. For instance, IEEE 802.22 WRAN(Wireless Regional Area Network) WG considered the CR technology as a solution of WRAN system to serve the high speed internet service(1.5 Mbps down stream and 384 kbps up stream) in 100 km overall coverage and 54 MHz-746 MHz band. Basically, in MAC point of view, the WRAN system have been standardizing based on the IEEE 802.16 MAC layer features such as Data transmission method, QoS provision and Bandwidth request schemes. Additionally, the WRAN system further include CR nature functions such as incumbent user protection, self coexistence which would be importantly considered. Also, the inherent WRAN functions are added such as channel bonding and fractional bandwidth usage. This paper mainly explained frame structure, IU protection, self coexistence which are key functions of WRAN system. Finally, in this paper, we expressed a prospect of IEEE 802.22 WRAN standardization.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2003.05a
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• pp.8-13
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• 2003

Historically, IP-based internets have been able to provide a simple best-effort delivery service to all applications they carry. Best effort treats all packets equally, with no service level, packet loss, and delay. But the needs of users have changed. The want to use the new real-time, multimedia, and multicasting applications. Thus, there is a strong need to be able to support a variety of traffic with a variety of quality-of-service requirements. The DiffServ architecture, proposed by the Internet Engineering Task Force(IETF), has become the most viable solution for provising QoS over IP networks. The DiffServ architecture does not specify any handling method between AF out-profile packets and BE packets. This paper propose a mechanism for supporting inter class fairness in the DiffServ architecture. Ⅰ proposed a modified Weighted Round Robin method to protect the BE traffic from AF out-profile packets in the core routers. The proposed technique is evaluated through simulation. Simulation results indicate that the proposed method provides better protection not only for BE packets from AF out-profile packets, but also for the AF in-profile packets in congested networks.

• Journal of Digital Contents Society
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• v.2 no.1
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• pp.73-79
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• 2001

Most of the existing algorithms try to disseminate the multimedia contents of internet service provider(ISP), without taking into account the needs and characteristics of specific websites including e-learning systems with web-based .educational contents. Sometimes the client must select the best one among the replicated repositories. However, this is a less reliable approach because clients' selections are made without prior information on server load capacity. In this paper we propose an agent system inspired by the need of improving QoS of delivering web-based educational multimedia contents without incurring long access delays. This agent system consists of three components, Analyzer, Knowledge Base, and Automaton embedded the capacity algorithm. It analyzes and investigates traffic information collected from individual replicated server by learners' requests, and selects a server which is available and is expected to provide the fastest latency time and the lowest loaded capacity, and achieves high performance by dynamic replicating web resources among multiple repositories.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.421-425
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• 2005

The increasing number of wireless subscribers who can use internet service any time and any place have caused wireless communications networks to flourish. However, since total communication channel bandwidth for wireless communications is limited, it is very important to find the solution for maximizing the channel utilization. Thus, in this work we propose a QoS packet scheduler for IEEE 802.11e EDCA scheme which is able to maximize the channel throughput with changing the CW value considering wireless channel condition. This proposed scheme is evaluated with NS-2 network simulator under various environments and it is easily shown from the numerical results that the proposed scheme provides better performance than that of the original IEEE 802.11e scheme.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.191-197
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• 2009

One of popular applications in the Internet is the multimedia streaming services such as IPTV or You Tube in which supporting quality of service (QoS) is an important issue. One of widely adopted rate control scheme is TCP-friendly rate control (TFRC) which shows comparable performance with TCP in term of throughput and lower variation of throughput over time. On the other hand, devices with multiple interfaces are emerging in the market. However, it has not proposed to exploit multiple interfaces simultaneously for multimedia streaming services with TFRC. In this paper, we propose a multimedia streaming algorithm with TFRC which exploits multiple interfaces to guarantee the quality of service. We show that the proposed scheme shows better performance than those with a single interface in terms of throughput and communication costs.

• Journal of KIISE:Software and Applications
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• v.26 no.11
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• pp.1306-1313
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• 1999

본 연구는 인터넷 기반 공유가상공간에서 시스템의 확장성을 유지하기 위하여 이동객체를 대상으로 하는 이벤트 필터링 기법을 제안하고자 한다. 제안된 다중격자 모델 기법은 이동객체의 경로 상에서 대표적인 이벤트를 샘플링하는 방식을 사용한다. 이 방식은 메시지 트래픽의 양을 동적으로 조절하기 위하여 이동객체 간의 관심정도 정보를 수치적으로 변환하여 이벤트 갱신빈도에 반영한다. 대량의 이동객체를 생성하여 제안된 기법을 적용한 성능평가 실험에서 기존의 방식에 비하여 평균 메시지 전송량이 50%이상 감소하는 것으로 확인할 수 있었다. 다중격자 모델은 참여자의 수와 메시지 트래픽 상황에 따라 가상환경의 공유 QoS를 동적으로 조절할 수 있으며, 인터넷 상에서 다수 사용자를 위한 3차원 가상사회 구축 및 온라인 네트워크 게임 개발 등에 활용될 수 있을 것이다.Abstract This paper proposes an event filtering technique that can dynamically control a large amount of event messages produced by moving objects like avatars or autonomous objects in a distributed virtual environment. The proposed multi-level grid model technique uses the method that extracts the representative events from the paths of moving objects. For dynamic control of message traffics, this technique digitizes the DOIs of the avatars and reflects the interest information controlling the frequency of message transmission. For the performance evaluation, a large number of moving objects were created and the model was applied to these avatar groups. In the experiments, more than 50% of messages have been reduced in comparison with the existing AOI-based filtering techniques. The proposed technique can dynamically control the QoS in proportion to the number of users and the amount of messages where a large number of users share a virtual space. This model can be applied to the development of 3D collaborative virtual societies and multi-user online games in the Internet.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.825-834
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• 2021

With the development of various devices and Internet platforms, production and demand for content are increasing rapidly. However, effective response to exponentially increasing data usage is difficult in current TCP/IP schemes. As a result, with the emergence of an alternative called CCN, data can be transmitted and received from the host-centered to the content-oriented, and large-capacity content can be handled with more mitigated network resources. In this paper, we will address intermediate node mobility, which is one of the areas studied in CCN. In CCN, real-time services are a very important factor for information providers as well as requestors. However, when a node departure situation occurs, packet transmission and transmission speed decreases. Therefore, to ensure these numbers, even if the intermediate node deviates using a dual path, it provides a complete QoS (Quality of Service) using an alternative path.