• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.10
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• pp.1-10
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• 2002

Scheduling technology is one of the most important elements required to support the Qos(quality of service) in the Internet and a lot of scheduling algorithms have been developed. However, most of there algorithms are not flexible in the distribution of the excess bandwidth. In order to improve the weakness of existing algorithms, DGPS(decoupled generalized processor sharing)has suggested recently. But, the DGPS algorithm is complex to implement and difficult to apply to the existing algorithms. In this paper, we propose a scheduling algorithm for distribution of the excess bandwidth which improves the implementation complexity of the DGPS and easy to be applied to ordinary algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.1-8
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• 2003

Scheduling technology is one of the most important elements required to support the Quality of service (QoS) in the Internet and a lot of scheduling algorithms have been developed. However, most of these algorithms ire not flexible to distribute the excess bandwidth. In order to provide flexibility for distributing the excess bandwidth, we proposed excess bandwidth fair queueing (EBFQ) algorithm with relatively low complexity. In this paper, we propose the new extension to this EBFQ algorithm for the hierarchical fair queueing system. This extension can be naturally applied to the existing hierarchical algorithm and simultaneously provide the same level of fairness. Through the simulation and analysis, we verify it.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.511-513
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• 2011

기존의 Wireless Mesh Network(WMN)에서 제안된 EFMP DSDV 기법은 우회 경로 이후의 잉여 대역폭이 좋지 않을 경우 우회하지 않았을 때보다 성능이 더 좋지 않은 경우가 발생한다. 이 같은 단점을 보완하기 위하여 본 논문에서는 우회 경로 다음 홉 간의 경로 정보인 Hop수와 잉여대역폭에 대한 정보를 획득하여 수식으로 유도된 Bypass값을 통해 각 우회경로의 비교를 제안한다.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.289-296
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• 2008

In wireless mesh network, studies on routing protocols have been actively carried out recently, and hop count is used as a major routing metric in destination-sequenced distance-vector (DSDV) routing protocol, which is a representative proactive routing protocol. Although hop-by-hop multi-path (HMP) DSDV and enhanced HMP (EHMP) DSDV routing protocols perform routing by considering both hop count and residual bandwidth within one hop distance nodes, it has a shortcoming that routing is carried out via non-optimal path from the aspect of end-to-end routing. In order to overcome the shortcoming, a cost-aware multi-path (CAMP) DSDV routing protocol is proposed in this paper, which considers hop count and end-to-end minimum residual bandwidth. Simulation results based on NS-2 show that the proposed routing protocol performs better than DSDV, HMP DSDV, and EHMP DSDV protocols from the aspect of throughput and packet delivery ratio, by appropriately using hop count and end-to-end minimum residual bandwidth information and has the same number of management messages with HMP DSDV and EHMP DSDV protocols.

• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.134-146
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• 2005

Research about QoS in the ad-hoc networks for stable service of various applications has been needed as the expectation about the realization of the ad-hoc networks grows bigger. Existing researches about QoS in the ad-hoc network had the problems which can not guarantee the quantitative services or create the overhead. In this paper, we propose a novel algorithm of QFAN(QoS Framework for Ad-hoc Networks) the framework to resolve such problems and considered application of the proposed algorithm into the ad-hoc networks. Our model can guarantee the minimum bandwidth of the real-time traffic as minimized the overhead. And, disproportionate distribution of bandwidth problem can resolve by the proposed algorithm through the fair share between real-time traffic and best-effort traffic about available bandwidth. We design both the TiRe(Tiny Reservation) and the ADR(Adaptive Drop Rate) control algorithm to apply the proposed QFAN. Using simulation, we confirm fair share of available bandwidth between real-time traffic and best-effort traffic as guarantee minimum required bandwidth of real-time traffic.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.170-175
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• 2008

모든 Network는 대역폭의 한계성을 갖고 있다. Overlay 구조의 Network 또한 예외는 아니다. 이러한 Network 대역폭 자원의 한계성은 Network를 이용한 많은 통신에 있어서 심한 Traffic 을 형성하고 그로 인한 낮은 대역폭을 제공해준다. 이에 대한 해결책으로 Multi-Hour Ability 를 적용할 수 있다. 우리가 살아가는 환경은 서로 다른 시간대가 존재하며, 그로 인한 생활패턴에 따라 Network를 이용하는 정도 또한 시간대별로 다르다. 이 논문에서는 라우팅이 자유로운 Overlay Network를 통해 Multi-Hour Ability를 적용하여 Network에 발생한 Traffic 을 완화시키고, 잉여 대역폭을 효과적으로 사용하며, 보다 안정적인 대역폭 확보를 통해 성능 향상을 할 수 있다는 것을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.669-672
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• 2008

In this paper, we propose a constant-amplitude multi-rode trans-bi-orthogonal modulation scheme by introducing a simple constant-amplitude coding scheme with redundant bits and trans-code, which if a modified orthogonal modulation scheme. Generally speaking, the orthogonal modulation scheme is not appropriate for the high speed data transmission applications because of bad bandwidth efficiency. Therefore, we use the multi-rode trans-bi-orthogonal modulation with trans-code for high bandwidth efficiency. Moreover, redundant bits are used for constant-amplitude-coding. Finally, we compare the performance of the proposed scheme with the orthogonal modulation and constant-amplitude multi-code trans-orthogonal modulation by using the computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.484-492
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• 2006

A multi-code biorthogonal code keying(MBCK) system consists of multiple waveform coding block, and the sum of output codewords is transmitted. Drawback of MBCK is that it requires amplifier with high linearity because its output symbol is multi-level. MBCK with constant amplitude preceding blcok(CA-MBCK) has been proposed, which guarantees sum of orthogonal codes to have constant amplitude. Redundant bits of CA-MBCK for constant amplitude coding are not only used to make constant amplitude signal but also used to improve the bit error rate(BER) performance at receiver. In this paper, we proposed a transmission scheme which combine CA-MBCK with $Q^{2}PSK$ to improve bandwidth efficiency of CA-MBCK. The BER performance of the scheme is same that of CA-MBCK in additive white gaussian noise(AWGN). And we showed that BER performance of the proposed system can be improved using redundant bits of constant amplitude preceding.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1541-1544
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• 2000

본 논문은 이동 컴퓨팅 환경에서 실시간 데이터의 전송시 발생하는 패킷 손실에 관한 문제를 다룬다. 현재 인터넷 상에서의 실시간 데이터 전송은 주로 RTP/RTCP 프로토콜[1]을 이용하는데, 이 프로토콜은 안정된 전송을 보장받지 못하며, 따라서 패킷 손실을 피할 수 없다[2,3]. 특히, 제한된 무선 대역폭과 높은 BER(bit error rate) 특성을 갖는 이동 컴퓨팅 환경에서는 기존의 인터넷보다도 더 많은 패킷들이 손실될 수 있다. 본 논문에서는, 이동 컴퓨팅 환경에서 실시간 데이터 전송시 발생되는 패킷 손실 특성을, 길버트 모델에 기초하여 확률적으로 분석하고, 이를 기반으로 새로운 복구 방법을 제안한다. 제안하는 실시간 데이터의 복구 방법에서는 패킷에 부가하는 잉여 데이터의 개수를 가변적으로 조절함으로써, 사용 중인 네트워크의 패킷 손실 특성을 반영할 수 있다. 특히, 잉여 데이터들의 오프셋 값들을 비연속적으로 설정함으로써, 간헐적이거나 연속적인 패킷 손실 모두에 대처할 수 있는 특징이 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9B
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• pp.838-847
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• 2006

In order to support multiple multimedia streaming services in home networks, many critical issues must be considered. In addition, handling the shortage of network bandwidth is one of the most significant and complicated issues. In this paper, real-time bandwidth management service is suggested as a solution to the problem regarding the IEEE1394-based home network. In order to handle the shortage of network bandwidth and to enhance the bus utilization rate, the proposed service combines two methods. First, the bus bandwidth management function determines the state of the network bandwidth and restores the residual bandwidth, which is excessively occupied by a streaming service, to the available free bandwidth. Second, the Isochronous Streaming (IS) Scheduler manages all streaming services according to priority. In order to test the proposed service, we implemented a prototype steaming management middleware and evaluated it by using the IEEE1394 network test-bed.