• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1998.04a
• /
• pp.293-297
• /
• 1998

본 논문에서는 화상, 음성, 화이트보드 등과 같은 멀티미디어 자원들을 상호 연동하여 진행하는 참호참여환경 프레임워크인 DooRate이 갖고 있는 세션 진행 시 고정된 멀티미디어 자원을 사용하는에 따른 문제점을 개선하는 방법을 설계하였다. 이 설계를 통하여 다양한 형태로 실시간 세션을 변형시킬 수 있을 뿐만 아니라 불필요한 미디어정보의 전송을 제거할 수 있어 시스템 및 네트워크 부하를 줄일 수 있도록 한다. 진행중인 세션의 변환 명령 패킷의 신뢰성있는 전송을 위하여 RMTL(Reliable Multipoint Transport Layer)방식의 IP Multicasting을 설계하였다.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2158-2170
• /
• 1999

It has been required more reliable communication on processes and improvement of system performance as distributed systems using multicast protocol became widespread. In distributed environment maintaining data consistency through asynchronous execution of processes and coordinating the activities of them would occurs. This paper proposes a total ordering algorithm, TORMP, in order to resolve these problems. TORMP takes advantage of multicast protocol and uses an effective token passing method. It reduces a process delaying time before transmitting its message by multicasting a token simultaneously to every process that initiates the request of the message. Moreover, the processes receiving the token start multicasting the message at the same time, which causes to cut down the overall transmission dely. In case that one process sends a message, TORMP hardly uses the procedure of controlling for ordering. It gives fairly the right of sending messages to all processes in a group with utilizing vector clock. In TORMP, unlike other algorithms, the number of packets generated during ordering process does not depend on the number of processes.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.5
• /
• pp.1525-1535
• /
• 2000

Multicast is the multiparty communication that allows one-to-many communications. There are some multicast applications which are the ways of multiparty communications such as video conference system and white board. This paper proposes a dynamic allocation mechanism of designated receiver by using designated receiver list and a retransmission mechanism with designated receiver for the effective multicasting dta transmission. We designed voice conference system with multicast based on RTP/RTCP. This voice conference system increases the effect of standardization work and enables to exchange reliable standard dta with real time.

• KIPS Transactions on Computer and Communication Systems
• /
• v.5 no.11
• /
• pp.385-392
• /
• 2016

Recently, Expectation Area-based Real-time Routing (EAR2) protocol has been proposed to support real-time routing in wireless sensor networks. EAR2 considers the expectation area of a mobile sink and uses flooding within the expectation area. However, flooding leads to excessive energy consumption and causes long delay against real-time routing. Moreover, since EAR2 uses single path to the expectation area, it is difficult to support reliable routing in sensor networks with high link failures. Thus, to overcome these limitation of EAR2, this paper proposes a reliable and real-time routing protocol based on virtual grids and multipath for mobile sinks. To support real-time routing, the proposed protocol considers expectation grids belonged to the expectation area. Instead of flooding within the expectation area, the proposed protocol uses multicasting to the expectation grids and single hop forwarding in an expectation grid because the multicasting can save much energy and the single hop forwarding can provide short delay. Also, the proposed protocol uses multipath to the expectation grids to deal with link failures for supporting reliable routing. Simulation results show that the proposed protocol is superior to the existing protocols.

• Smart Media Journal
• /
• v.2 no.1
• /
• pp.8-16
• /
• 2013

The significant enhancement of the edge portion of computer networks including user-side machines and last mile network links encourages the research of the overlay network based data dissemination systems. Varieties of overlay network based data dissemination systems has distinct purposes, and each of them has a proper structure of an overlay network and a efficient communication protocol. In this paper, overlay network based data dissemination systems for Flash Dissemination, whose target is the distribution of relatively small size data to very large number of recipients within very short time, are explored. Mainly two systems, RECREW and FaReCAST, are introduced and analyzed in the aspects of design considerations for overlay networks and communication protocols. According to evaluations for flash dissemination scenarios, it is observed that the proposed overlay network based flash dissemination systems outperforms the previous overlay network based multicasting systems, in terms of the reliability and the dissemination delay. Moreover, the theoretical analysis of the reliability of data dissemination is provided by analysing FaReCAST.

• Journal of Korea Multimedia Society
• /
• v.6 no.6
• /
• pp.1025-1033
• /
• 2003

The CDN is proposed as a solution of network bottleneck problem resulting from the rapid growth of Internet user and multimedia contents on the Internet. This paper suggests MDC and path diversity between CDN Edge server and end-user, and multicast transmission among CDN servers based on CDN infrastructure. It may be a solution for reliable and fast transmission of rich multimedia contents. These research will support to solve the unreliable transmission problem of multicasting and to create the new business models in the field of web contents.

• Journal of the Optical Society of Korea
• /
• v.11 no.2
• /
• pp.59-62
• /
• 2007

In this paper, we introduce a reliable, scalable, and cost-effective switchless wavelength division multiplexing (WDM) network based on a quality-of-service supporting reservation-based medium access control (MAC) protocol. The protocol not only provides both packet and circuit switching but also supports multicasting. The network efficiency is significantly increased by spatially reusing wavelengths and exploiting multiple free spectral ranges (FSRs) of arrayed waveguide grating (AWG) employed in the architecture. We have demonstrated the feasibility of this architecture by simulating in $Optsim^{TM}$.

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.629-631
• /
• 2003

본 논문에서는 IP 네트워크 환경에서 이동 사용자에게 멀티캐스트 전송을 보다 효율적으로 지원하기 위해 새로운 프로토콜 EMP(Enhanced Multicast Protocol)을 제안한다. 제안한 EMP는 이동 사용자의 이동성을 지역적으로 관리[5]하므로써 원격가입 방식에서 발생하는 빈번한 멀티캐스트 트리 갱신의 비용을 줄이고 가입/탈퇴로 인해 발생되는 시그널링 지연과 패킷 손실을 완화하였다. 또한 EMP는 양방향 방식에서 발생하는 비효율적인 삼각라우팅(Triangle routing)과 터널링 집중(Tunneling convergence) 현상[4]이 발생하지 않는다. 만약 패킷 손실이 발생하면 RFA(Root of FA)를 통해 회복하므로 회복 절차에 대한 오버헤드가 감소되었다. 따라서 제안된 EMP는 좁은 지역보다는 넓은 지역에서 효율성이 높기 때문에 광범위한 지역에서 사용될 수 있다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.04a
• /
• pp.503-506
• /
• 2001

무선 멀티캐스팅에서 이동 호스트의 기지국간 이동은 멀티캐스트 그룹 내의 이동과 그룹 외의 이동에 따라 각기 다른 신뢰성 문제가 발생한다. 그룹내의 기지국으로 이동시에는 이동 호스트가 원하는 데이터를 해당 기지국이 이미 삭제한 상태라면 이전의 기지국에서 필요한 데이터를 재전송하여야한다. 그룹 외의 기지국으로 이동시에도 역시 필요한 데이터를 포워딩해야한다. 이와 같은 데이터 재전송과 포워딩은 전송 지연과 대역폭의 낭비를 발생시킨다. 본 논문에서는 이와 같은 무선 멀티캐스팅에서의 신뢰성 문제를 해결하기 위한 기법으로 IES(Information Exchange Scheme)을 제안한다. 제안된 IES에서는 멀티캐스트 그룹 기지국간에 멤버쉽과 데이터 수신 정보를 교환함으로써 MH의 이동 범위에 상관없이 신속하고 정확한 전송을 기대할 수 있다. IES를 평가하기 위해 기존의 기법들과 비교 분석하였고 그 결과로 제안된 IES가 효과적인 기법임을 증명한다.

• Journal of KIISE:Information Networking
• /
• v.28 no.4
• /
• pp.559-569
• /
• 2001

With the growth of the Internet, applications using the reliable multicast protocol are increasing. Two important requirements of reliable multicasting are reliability and scalability. To enhance scalability, many methods have been proposed. A typical method is a local recovery scheme. This paper proposes a new stable and effective protocol with the following features. The first is to apply the discipline of the separations of concerns to NAK message. By dividing the functions of the NAK message into the error recovery request and the NAK-suppression, each function can be optimized. Second, a local representative, which is selected gradually and distributively, executes error recovery in somewhat deterministic manner. Finally, by dynamically adjusting the TTL value of the control message, the error recovery domain can be optimized. The proposed scheme has been implemented and experimented on Network Simulator. Compared to the existing schemes, the performance results show that scalability has not only been enhanced but also error recovery time and network overhead have been reduced.