• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.35-42
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• 2003

In this paper, we classified the wavelength reservation mechanisms of optical burst switching (OBS), and investigated the path length priority effect of the offset time/delayed reservation (OT/DR)-based scheme like the just-enough-time (JET) protocol. And, we showed that the fiber delay line (FDL)-based scheme can avoid the path length priority effect in multiple hop network environments. Also, we proposed a novel FDL/DR with hop-by-hop priority increasing (HPI) scheme which can improve the end-to-end throughput by increasing the priority of bursts hop-by-hop using the input FDLs at each node. The simulation results showed that the proposed FDL/DR with HPI scheme could avoid the path length priority effect and enhance the end-to-end throughput in multiple hop network environments.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.519-524
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• 2007

One of the most important issues on the sensor network with resource limited sensor nodes is prolonging the network lifetime by effectively utilizing the limited node energy. The most representative mechanism to achieve a long lived sensor network is the clustering mechanism which can be further classified into the single hop mode and the multi hop mode. The single hop mode requires that all sensor nodes in a cluster communicate directly with the cluster head(CH) via single hop md, in the multi hop mode, sensor nodes communicate with the CH with the help of other Intermediate nodes. One of the most critical factors that impact on the performance of the existing multi hop clustering mechanism is the cluster size and, without the assumption on the uniform node distribution, finding out the best cluster size is intractable. Since sensor nodes in a real sensor network are distributed non uniformly, the fixed size mechanism may not work best for real sensor networks. Therefore, in this paper, we propose a new dynamic size multi hop clustering mechanism in which the cluster size is determined according to the distance from the sink to relieve the traffic passing through the CHs near the sink. We show that our proposed scheme outperforms the existing fixed size clustering mechanisms by carrying out numerical analysis and simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.237-239
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• 2011

본 논문에서는 클러스터 기반 다중 홉 무선 네트워크에서 중계기 협력 ARQ 를 이용한 기회적 중계 기법을 제안한다. 클러스터 간 통신 시 성능을 열악하게 만들 수 있는 채널 페이딩 효과를 줄이기 위하여 각 클러스터 간 통신에 중계기를 이용한 협력 통신을 적용한다. 또한 다중 홉 통신에서는 중간 홉에서 오류가 발생할 경우 전송 도중 정보를 잃게 되는 전송 실패의 가능성이 존재한다. 따라서 전송 실패의 가능성을 줄이기 위하여 중계기로부터 재전송을 받을 수 있는 중계기 협력 ARQ 기법을 적용한다. 본 논문에서는 제안한 기법에 대한 전송 실패 확률을 분석한다. 그리고 모의 실험에서는 제안한 기법이 ARQ 를 사용하지 않은 기법과 성능 비교하여 신뢰도 측면에서 더 좋은 성능을 보임을 확인한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.99-101
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• 2012

본 논문에서는 하나의 타임 슬롯이 홉 수보다 적은 수의 페이즈로 분할되는 새로운 다중 홉 통신 시스템을 제안한다. 또한 제안한 시스템의 성능을 분석하고 최적화하는 방법을 제안한다. 컴퓨터 모의실험을 통하여 시스템 성능 분석의 유효성을 확인할 수 있으며, 기존의 다중 홉 통신 시스템보다 향상된 성능을 확인할 수 있다. 특히, 경로 손실 지수가 증가할수록 성능 향상 폭이 큰 것을 확인할 수 있다.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.91-96
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• 2000

차세대 무선 통신 서비스의 응용은 다양한 형태로 발전하고 있다. 그 중에서 응급상황이나 학내망 같이 특수한 경우에 제공될 수 있는 시나리오로 다중 홉(Multi-hop) 다중 링크(Multi-link) ad-hoc 망을 들 수 있다. Ad-hoc망은 한정된 자원 문제와 변화가 심한 링크 용량문제가 있으며, 다중 홉상의 노드가 이동함으로 토폴로지의 동적 변화문제도 발생한다. 이러한 망의 노드는 송·수신단 역할을 할 뿐만 아니라 패킷을 전달하는 중간 노드의 역할도 하기 때문에 파워의 절약 매카니즘이 절실히 필요하게 된다. 본 논문은 PAMAS에 기반하여, 별도의 제어 채널에 버퍼를 두어 송·수신자 주소와 전송할 데이터의 크기의 정보를 버퍼에 기록하여 예약하고 제어 채널에서 데이터 채널의 파워를 제어할 수도 있으므로 데이터 전송에서 충돌을 예방하고 효율적으로 파워를 절약할 수 있다. 데이터 전송 발생율을 바꿔가며 시뮬레이션 결과 일반적인 방법을 사용한 노드들보다 훨씬 좋은 파워 절약을 이루고 있음을 알 수 있었다.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.634-639
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• 2008

In mobile communication networks, the main power consumption is due to the actual transmissions power. Therefore, power efficiency network structures have gained considerable importance in mobile multi-hop systems and networks in recent years. In this paper, the performance of mobile multi-hop wireless system with M-QAM signal and forward error control (FEC) technique are analyzed The FEC technique uses extra processing power related to encoding and decoding, it is need complex functions to be built into the communication node. The probability of receiving a correct bit and codeword for relaying a data frame over h hop relay station to the final station is evaluated as a function of channel parameter and number of hops, and the distance between the different station.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.598-599
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• 2015

For the wireless mesh networks, efficient routing protocol is required to transmit data from source to destination node through multi-hop transmission. Multipath routing enable the stable data transmission even in the case of traffic congestion or unstable link. In this paper, we propose partial multipath routing which does not make a full multipath but partial for some parts of unstable links. This partial multipath routing reduce the number of nodes for routing and minimized the required power.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1917-1924
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• 2015

Efficient routing algorithm is required to transmit data from source to destination by multi-hop transmission in wireless sensor networks. In the multi-hop transmission, multipath routing can be one of the solutions to cope with the traffic congestion and unstable link condition. In this paper, we propose partial multipath routing which does not establish a secondary full routing path but a partial multipath to complement some poor links, and it can enable stable data transmission and reduce the number of nodes in routing path and the required total power compared with conventional multipath routing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.8
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• pp.19-24
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• 2012

In this paper, we analyze the maximum throughput of opportunistic routing along a long-haul multi-hop wireless network path for a single data stream, while considering link-level interference among the network nodes. Surprisingly, we find out that opportunistic routing does not provide much improvement in throughput for long-haul paths. The results of this research show that when we compare the extra cost for the complex implementation of the opportunistic routing scheme to the performance improvement obtained from it, opportunistic routing scheme needs to be applied to only short-haul multi-hop wireless network paths.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.45-49
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• 2011

Cooperative multihop communications support effective transmissions over underwater acoustic channels as inferior wireless channels. But the performance of cooperative multihop systems may degrade due to the lack of cooperative nodes at the initial operation time duration. At the initial time duration, the lack of cooperative nodes causes more errors, and the multihop network propagates these errors. In this paper, we apply fountain code to the cooperative multihop system at the initial time duration, and show performance improvements by simulations.