• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8A
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• pp.625-632
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• 2009

This paper presents the mobile IPTV system for the transmission of FGS-encoded video stream over WiMAX network. The proposed system is implemented to provide more subscribers with an improved mobile IPTV service considering the scarce resource constraint. The proposed system pursues an efficient tradeoff between the number of subscribers that receive the enhancement layer stream and their IPTV service quality. In the proposed system, some parts of the enhancement layer are transmitted with the modulation scheme and the coding rate adaptive to wireless link states of subscribers. Finally, experimental results are provided to show the performance of proposed mobile IPTV system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8A
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• pp.689-697
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• 2012

In this paper, we propose base layer repetition and HARQ schemes for improving the reliability and the performances of H.264 SVC video transmission in a wireless channel, and investigate its performances. The proposed method may solve the problems of transmission delay as well as the scarcity of wireless resources, since the proposed scheme was applied for only base layer, not for enhancement layer. The numerical results show that the proposed scheme can enhance the BER performance of $1.5{\times}10^{-5}$ and the FER of $1.2{\times}10^{-3}$, when SNR=3.4dB. Also, it was confirmed through the resultant images that the proposed method can improve the SVC performance in the wireless link.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1386-1396
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• 1996

In the distributed multimedia application, high throughput and low delay is one of the most important QoS(Quality of Service) requirement. Emerging high speed communication offers transmission rate above Gbps, but it can not be utilized efficiently by the performance bottlenecks of communication protocols. To overcom the problem, we propose a horizontal processing architecture that processes data as soon as it arrive from the network. Unfortunately, the OSI protocol stack often imposes ordering constraints that prevent concurrent processing of the protocol layers. By using a fixed packet format, the network layer through the presentation layer are processed in parallel. Our prototype shows that the proposed model has performance improvement up to 61% more advantage than the conventional approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11A
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• pp.903-911
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• 2011

In this paper we proposed an energy adaptive data aggregation and transmission mechanism to solve the problem of energy limitation in wireless sensor networks (WSNs). Hierarchical structure methods are wildly used in WSNs to improve the energy efficiency. LEACH and TEEN protocols are the typical techniques. In these methods, all nodes, including nodes who have sensed data to transmit and nodes who haven't, are set frame timeslots in every round. MNs (member nodes) without sensed data keep active all the time, too. These strategies caused energy waste. Furthermore, if data collection in MNs is same to the previous transmission, it increases energy consumption. Most hierarchical structure protocols are developed based on LEACH. To solve the above problems, this paper proposed a method in which only MNs with sensed data can obtain allocated frame to transmit data. Moreover, if the MNs have same sensed data with previous, MNs turn to sleep mode. By this way redundant data transmission is avoided and aggregation in CH is lightened, too.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.4 s.304
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• pp.59-68
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• 2005

In this paper, we design a PCI Express controller for future communication system The controller supports the full functionality of Transaction Layer and Data Link Layer of PCI Express. The designed controller has the proposed transmitter buffer architecture to obey Replay mechanism. This scheme merges the transmitting buffer and the replay buffer. The proposed buffer has the higher data transfer efficiency than the conventional buffer architecture because it can dynamically adjust size of a replay buffer space. We also design transmitter of Transmitter Transaction Layer to effectively support the proposed buffer, The receiver device of PCI Express must possess the buffer for three types of transaction to support Flow Control. And it must report the amount of the buffer space regularly to the Port at the opposite end of the link. We propose the simple receiver buffer scheme using only one buffer to easily support Flow Control. And the designed controller is verified under proposed test bench

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.95-98
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• 2008

국내외적인 이동멀티미디어 방송 시장의 급속한 성장과 더불어 동일한 주파수 대역에서 기존 T-DMB 시스템에 비해 더 많은 데이터 전송률을 얻기 위해, T-DMB 시스템에 계층변조를 적용하여 전송률을 높이는 연구가 국내외적으로 추진되고 있다. 기존 T-DMB 시스템의 DQPSK 신호에 새로운 변조방식으로 변조된 신호를 더하여 계층변조 하는 경우에, 새로 추가되는 신호에는 한 개 이상의 변조방식이 적용될 수 있다. 이러한 경우의 일례는 DQPSK-BPSK 및 DQPSK-QPSK 변조가 있을 수 있다. 이와 같이 새로 추가되는 신호에 한 개 이상의 변조방식이 적용된 경우에, 수신단에서 새로 추가된 신호에 적용된 변조방식을 용이하게 검출하기 위한 수단이 필요하다. 이것을 위하여 PRS 신호에 PN 시퀀스를 계층변조 형태로 추가하여 수신단에서 PN 시퀀스의 상관을 취하여 새로 추가되는 신호의 변조방식을 검출하는 방법을 제안하고, 실험 결과를 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.514-516
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• 2004

본 논문에서는 이동 애드혹 망에서 멀티미디어 트래픽 처리를 위해 예약 방식의 매체 접근 제어(MAC) 프로토콜을 설계하고 그 성능을 평가하였다. 예약 방식의 MAC 프로토콜은 두 개의 부분 계층으로 이루어진 계층적 접근법을 기반으로 한다. MAC의 하위 부분 계층은 이동 애드혹 망에서 비동기 데이터 트래픽을 지원하기 위해 CSMA/CA를 사용하는 기본적인 접근 방법을 제공한다. 그 위에 상위 부분 계층은 실제 데이터 전송에 앞서 슬롯(slot) 예약을 수행함으로써 실시간 주기적 트래픽을 지원한다. 제안된 프로토콜은 소프트웨어 시뮬레이터를 사용하여 검증하였다. 시뮬레이션 수행 결과는 예약 방식의 MAC 프로토콜이 IEEE 802.11 표준과 비교하여 실시간 트래픽 전송에 더 적합함을 보여주었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1419-1420
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• 2009

SCTP(Stream Control Transmission Protocol)는 새로운 전송계층 프로토콜로 TCP와 UDP의 장점을 결합한 대체 프로토콜로 기대되고 있다. 다양한 환경에서의 연구와 함께 SCTP에서 보안서비스를 제공하는 보안메커니즘에 관한 연구도 활발히 진행되고 있다. SCTP를 위한 E2E 보안메커니즘은 대부분 4계층 이상에서의 보안서비스를 결합한 방식으로 제안되고 있으며, IP계층에서의 보안을 위한 IPSEC은 멀티호밍의 특성을 적절히 지원하지 못하고 있다. 그래서 IP계층에서의 IP주소인증 및 IP패킷의 보안서비스 제공을 위한 보안메커니즘이 요구된다. 본 논문에서는 멀티호밍의 SCTP에서 각 IP주소를 인증하고 비밀키를 공유하는 인증메커니즘을 제안한다.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.183-191
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• 2008

In this paper, we propose Stream Control Transmission Protocol(SCTP) proxy which supports making an SCTP connection from a Corresponding Node(CN) to a Mobile Node(MN). Recently, mobility support in transport layer is proposed, which provides mobility in end-to-end way using the extension of SCTP. Mobile SCTP can provide handover to all applications that use SCTP as a transport protocol. However, current SCTP does not include independent location management service and can not make connection from a CN to a MN without assistance of other mobile protocols. To solve this problem, Proposed SCTP proxy interoperates with generic location management service and performs an address transformation to forward connection set up messages to the MN. Using the proposed proxy, SCTP can provide a complete mobility support including a connection setup to the MN and maintaining an existing connection.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.3 s.303
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• pp.31-40
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• 2005

In this paper, we develop an approach toward JSC(Joint Source-Channel Coding) method for MPEG-4 based FGS(Fine Granular Scalability) video coding and transmission in fixed and mobile receiving environment(Digital Audio Broadcasting, DAB). The source coder used MPEG-4 FGS video codec, the channel coder used RCPC(Rate Compatible Punctured Convolution) code and the modulation method used QPSK modulation. We have considered channel environment of AWGN and mobile receiving environment. This study determined optimum Trade-off point between source bit rate and channel coding rate in variable channel states. We compared FGS-JSC method and general single layer CBR(Constant Bit Rate) transmission. In this results, FGS-JSC was appeared better performance than CBR transmission.