• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.791-793
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• 2015

Recently, UCC (User Created Contents) and VoD (Video on Demand), and multimedia content are growing, IP-TV, Smart TV, OHTV (Open Hybrid TV) various services such as multi platform (Multi-platform) environment, services and QoS issues. To solve this problem, the network efficiently, and improve the quality of content is necessary for the system. In this paper, the network of channels State and transmission of multimedia data based on dynamic resource usage, TCP and UDP, Adaptive dual-streaming system used for design and analysis. In addition, the existing TCP and UDP streaming system using a single protocol for analysis and verification of the effectiveness of the difference between and. This is a disaster, and medical/first aid system will be utilized in the field of feed, are ubiquitous.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.280-286
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• 2004

The widespread use of the Internet and the maturing of digital video technology have led to an increase in various streaming media application. However, new classes of hosts such as mobile devices are gaining popularity, while the transmission became more heterogeneous. Due to the characteristics of mobile networks such as low speed, high error bit rate, etc., the applications over the wireless channel have different needs and limitations from desktop computers. An intermediary between two communicating endpoints to hide the heterogeneous network links is thought as one of the best approaches. In this paper, we adopted the concept of inter-packet gap and the sequence number between continuously received packets as the error discriminator, and designed an adaptive packet sizing mechanism to improve the network efficiency under varying channel conditions. Based on the proposed mechanism, the packetization scheme with error protection is proposed to scalable encoded video delivery. Finally, simulation results reveal that our proposed mechanism can react to the varying BER conditions with better network efficiency and gain the obvious improvement to video quality for stored MPEG-4 FGS video delivery.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3446-3464
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• 2017

Backoff mechanism serves as one of the key technologies in the MAC-layer of wireless mobile networks. The traditional Binary Exponential Backoff (BEB) mechanism in IEEE 802.11 Distributed Coordination Function (DCF) and other existing backoff mechanisms poses several performance issues. For instance, the Contention Window (CW) oscillations occur frequently; a low delay QoS guarantee cannot be provided for real-time transmission, and services with different priorities are not differentiated. For these problems, we present a novel Multi-Priority service differentiated and Adaptive Backoff (MPAB) algorithm over IEEE 802.11 DCF for wireless mobile networks in this paper. In this algorithm, the backoff stage is chosen adaptively according to the channel status and traffic priority, and the forwarding and receding transition probability between the adjacent backoff stages for different priority traffic can be controlled and adjusted for demands at any time. We further employ the 2-dimensional Markov chain model to analyze the algorithm, and derive the analytical expressions of the saturation throughput and average medium access delay. Both the accuracy of the expressions and the algorithm performance are verified through simulations. The results show that the performance of the MPAB algorithm can offer a higher throughput and lower delay than the BEB algorithm.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.307-316
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• 2004

Wireless local area networks have known an increasing popularity during the past few years. However, as new user applications diverge from the traditional data-centric model, the introduction of efficient, QoS aware medium access methods becomes of utmost importance. EY-NPMA is a medium access protocol belonging to the contention paradigm that provides support for service differentiation and low collision rates. In this paper, we address a shortcoming of EY-NPMA as indicated by previous studies, namely the insensitivity of the protocol to different working conditions. In this work, we study and evaluate a mechanism that allows a network employing EY-NPMA to adapt its operating parameters according to the offered load. Simulation studies further document and confirm the positive characteristics of the proposed mechanism.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.361-363
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• 2002

통신망은 수많은 망관리시스템(NMS)과 프로토콜, 그리고 계속 등장하는 새로운 기능으로 이루어져 있다. 통합(integration)은 다양한 기술을 수용하기 위한 방법이지만 복잡함을 동반하며, 기술의 통합은 서로 다른 관리 영역간의 상호 운용성이 요구되는 기능이다. 본 논문에서는 다양한 프로토콜을 망 관리에서 수용하여 통합 관리될 수 있도록 CORBA기능을 활용한 선택적 이벤트서비스 기능을 제시한다. 또한 선처리 시스템(Front End Processor)을 이용하여 통신망의 트래픽을 최소화하고 필터링(filtering)을 효율적으로 할 수 있는 방식을 제안한다. 본 논문에서 제시한 구조는 과거 QoS나 오류복구 등을 제외한 기능을 FEP 호스트에 유지함으로서 다양한 프로토콜을 안정적으로 처리하는 서비스가 가능하다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.735-742
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• 2007

We propose an effective packet marking algorithm for video streaming in DiffServ network. Because legacy packet markers such as srTCM(single rate three color marker) cannot distinguish the importance of packet, these markers can cause quality degradation of streaming during the network congestion period. Recently proposed TMS (Two Marker System) [4] shows effectiveness in such scenario that video streaming service is struggling with other types of service traffic. However, if many video streaming services co-exist in DiffServ network and result in competition among themselves, then both legacy packet markers and even TMS cannot prevent drastic streaming quality degradation. To cope with this, we suggest A-TCPM (Adaptive time sliding window Three Color Marker) algorithm. In this algorithm, an A-TCPM module decides the color of a racket based upon the probability which is lead by current channel status and frame importance ratio. Simulation results show that proposed A-TCPM algorithm can enhance streaming service quality especially when overbooked video streaming sessions struggle with themselves.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.139-148
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• 2005

The desired level for multimedia services in the mobile web environment, the next generation web environment, is expected to be of PC level quality. And great efforts have been made in the development of hadware technology, communication technology, various kinds of services and standardization to support these services, In the mobile web environment, multimedia contents adaptation services should be available through supporting various kinds of devices, network abilities and users' preferences. It means that due to the variety of both desired devices' hardware specifications, called destinations, and desired QoSes, the QoSes in the destinations are not fixed or defined. If a new user wants to stream multimedia contents in a server through a new kind of terminal device, it should be considered whether the existing transcoders are able to adapt the multimedia contents. However, the existing libraries for multimedia adaptation have heavy transcoder figures which include all adaptive functions in one library, The challenge of universal access is too complex to be solved with these all in one solutions. Therefore, in this paper we propose an application independent multimedia adaptation framework which meets the QoS of new and varied mobile devices. This framework is composed of a group of unit transcoders having only one transcoding function respectively, Instead of heavy transcoders. Also, It includes the transcoder manager supporting the dynamic connections of the unit transcoders in order to satisfy end to end QoS.

• Journal of the Korea Society of Computer and Information
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• v.16 no.11
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• pp.45-56
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• 2011

WBAN is short range wireless communication technology which is consists of several small devices close to, attached to or implanted into the human body. WBAN is classified into between medical and non-medical by applications based on technology and medical data with periodic characteristics is used the GTS method for transmitting data to guarantee the QoS. In this paper we proposed algorithm that resolve lack of GTSs while data transmit GTS method in superframe structure of WBAN. Coordinator dynamically allocates GTSs according to the data rate of devices and make devices share GTSs when lack of GTSs. We compared delay bounds, throughput for performance evaluation of the proposed algorithm. In other words, we proposed algorithm adaptive WFQ scheduling that GTS allocation support differential data rate in environments of WBAN. The experiment results show the throughput increased and the maximum delay decreased compared with Round Robin scheduling.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.4
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• pp.218-228
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• 2008

The convergence of broadcasting and telecommunication services is being accelerated by broadband networks, digital broadcasting and Web2.0. This paper describes the definition and service characteristics of IPTV as a representative of broadcasting and telecommunication convergence services. Especially, the changes of infrastructure and technology for IPTV2.0 are addressed in terms of the service features of mobility, intelligence and participation. IPTV2.0 shall be characterized by the open IPTV service based on Web2.0 and the mobile IPTV service over the heterogeneous networks employing various wireless/wired access technologies. The IP Multimedia Subsystem (IMS) and Service Delivery Platform (SDP) technologies are increasingly considered to support the personalization and openness. The mobility management technology is being evolved to provide QoS-guaranteed mobile communication services to users at anytime and anywhere. IPTV2.0 services and platforms are also anticipated to be core components to achieve knowledge-based ubiquitous society. IPTV2.0 contents are required to be integrated with the enhanced metadata to efficiently support search, selection, convergence and delivery of the contents. Moreover, those contents shall be enhanced to provide the scalable services which is adaptable to the network status and user preferences. Therefore, the networking technologies for IPTV2.0 should tightly cooperate with application services and adaptive contents. Those technologies will be developed to construct the ubiquitous content service platform considering the evolution of networks and various converged services.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.6
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• pp.205-212
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• 2003

Because a wireless ad hoc network does not have fixed infrastructure, a call admission control approach researched in a wireless network is not feasible to this network. In this paper, we propose call admission control scheme to support this problem and the burst handoff traffic due to group mobility in a wireless ad hoc network. This scheme is an adaptive guard channel scheme which adapt the number of guard channels in each MBS(mobile base station) according to the current estimate of the potential handoff call rate derived from the number of ongoing calls within the coverage area of an MBS that initiate group handoff in a wireless ad hoc network. Our simulation studies are performed for comparisons of the proposed scheme with the other channel allocation schemes. Simulation results show that the proposed scheme efficiently reduces handoff call blocking probability in wireless ad hoc networks.