• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1256-1275
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• 2014

As one of the new self-organizing and self-configuration broadband networks, wireless mesh networks are being increasingly attractive. In order to solve the load balancing problem in wireless mesh networks, this paper proposes a novel multi-path routing algorithm based on clustering (Cluster_MMesh) for wireless mesh networks. In the clustering stage, on the basis of the maximum connectivity clustering algorithm and k-hop clustering algorithm, according to the idea of maximum connectivity, a new concept of node connectivity degree is proposed in this paper, which can make the selection of cluster head more simple and reasonable. While clustering, the node which has less expected load in the candidate border gateway node set will be selected as the border gateway node. In the multi-path routing establishment stage, we use the intra-clustering multi-path routing algorithm and inter-clustering multi-path routing algorithm to establish multi-path routing from the source node to the destination node. At last, in the traffic allocation stage, we will use the virtual disjoint multi-path model (Vdmp) to allocate the network traffic. Simulation results show that the Cluster_MMesh routing algorithm can help increase the packet delivery rate, reduce the average end to end delay, and improve the network performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2052-2067
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• 2011

Complementary trees are two spanning trees rooted at the sink node satisfying that any source node's two paths to the sink node on the two trees are node-disjoint. Complementary trees routing strategy is a special node-disjoint multi-path routing approach. Several complementary trees routing algorithms have been proposed, in which path discovery methods based on depth first search (DFS) or Dijkstra's algorithm are used to find a path for augmentation in each round of path augmentation step. In this paper, a novel path discovery method based on multi-tree-growing (MTG) is presented for the first time to our knowledge. Based on this path discovery method, a complementary trees routing algorithm is developed with objectives of low average path length on both spanning trees and low complexity. Measures are employed in our complementary trees routing algorithm to add a path with nodes near to the sink node in each round of path augmentation step. The simulation results demonstrate that our complementary trees routing algorithm can achieve low average path length on both spanning trees with low running time, suitable for wireless sensor networks in industrial scenarios.

• 한국정보과학회논문지:정보통신
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• 제35권4호
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• pp.292-300
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• 2008

무선 메쉬 네트워크나 무선 센서 네트워크와 같은 다중-홉(Multi-hop) 무선 네트워크에서는 노드들이 배터리를 이용하여 작동하는 경우가 많기 때문에 에너지 효율적인 라우팅이 중요한 문제이다. 지금까지 가장 에너지 효율적인 경로를 찾는 여러 기법들이 제안되었지만 이런 방식은 찾아낸 경로만을 사용함으로써 그 경로 상의 노드들의 에너지가 집중적으로 소모되어 네트워크의 전체적인 수명(lifetime)을 최대화하지 못한다는 단점을 가진다. 또한 이런 단점에 착안하여 네트워크의 수명을 최대화하기 위해 여러개의 경로들을 변경해가며 사용하는 기법들 역시 제안되었지만 경로 설정 및 변경 시에 발생하는 오버헤드가 크다는 한계를 가지고 있다. 본 논문은 선형 프로그래밍(Linear Programming)을 이용하여 네트워크의 수명을 최대화시키는 다중 최적 라우팅을 구하고 그 결과에 단일 최적 라우팅을 구하는 근사 알고리즘(approximation algorithm)을 적용하는 방식을 제안한다. 시뮬레이션을 통해 제안한 방식의 성능을 기존의 다른 기법들의 성능과 비교한다.

• 한국컴퓨터정보학회논문지
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• 제21권6호
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• pp.77-81
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• 2016

This paper deals with the optimization problem that decides the routing of connection between multi-source and multi-sink. For this problem, there is only in used the mathematical approach as linear programming (LP) software package and has been unknown the polynomial time algorithm. In this paper we suggest the heuristic algorithm with $O(mn)^2$ time complexity to solve the optimal solution for this problem. This paper suggests the simple method that assigns the possible call flow quantity to augmenting path of ($s_i,t_i$) city pair satisfied with demand of ($s_i,t_i$). The proposed algorithm can be get the same optimal solution as LP for experimental data.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.702-704
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• 2010

무선 LAN(Local Area Network) 환경에서 QoS를 지원하기 위해 IEEE 802.11 Working Group은 IEEE 802.11e를 표준화하였다. IEEE 802.11e EDCA는 우선순위가 높은 트래픽의 채널 접근 기회를 확률적으로 높임으로써 QoS를 지원한다. 이는 우선순위가 높은 트래픽이 우선순위가 낮은 트래픽에 비해 채널 접근을 반드시 먼저 하는 것이 아니다. 따라서 모든 트래픽이 같은 채널, 같은 routing path를 가진다면, 우선순위가 낮은 트래픽은 우선순위가 높은 트래픽의 성능에 지속적인 영향을 미친다. 결과적으로 EDCA는 음성이나 비디오와 같은 멀티미디어 응용에 QoS를 보장하기에 무리가 따른다. 본 논문에서는 이러한 문제점을 해결하기 위해 Multi-Interface를 이용한 Multi-Path Routing Algorithm을 제안한다. 각 Interface 마다 IEEE 802.11e EDCA에서 사용하는 Access Category별로 각각의 Routing Path를 다르게 함으로써 높은 우선순위의 트래픽에 QoS를 보장한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1846-1850
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• 2005

This paper presents a constrained-based routing (CBR) algorithm called, Dynamic Possible Path per Link (D-PPL) routing algorithm, for MultiProtocol Label Switching (MPLS) networks. In MPLS on-line routing, future traffics are unknown and network resource is limited. Therefore many routing algorithms such as Minimum Hop Algorithm (MHA), Widest Shortest Path (WSP), Dynamic Link Weight (DLW), Minimum Interference Routing Algorithm (MIRA), Profiled-Based Routing (PBR), Possible Path per Link (PPL) and Residual bandwidth integrated - Possible Path per Link (R-PPL) are proposed in order to improve network throughput and reduce rejection probability. MIRA is the first algorithm that introduces interference level avoidance between source-destination node pairs by integrating topology information or address of source-destination node pairs into the routing calculation. From its results, MIRA improves lower rejection probability performance. Nevertheless, MIRA suffer from its high routing complexity which could be considered as NP-Complete problem. In PBR, complexity of on-line routing is reduced comparing to those of MIRA, because link weights are off-line calculated by statistical profile of history traffics. However, because of dynamic of traffic nature, PBR maybe unsuitable for MPLS on-line routing. Also, both PPL and R-PPL routing algorithm we formerly proposed, are algorithms that achieve reduction of interference level among source-destination node pairs, rejection probability and routing complexity. Again, those previously proposed algorithms do not take into account the dynamic nature of traffic load. In fact, future traffics are unknown, but, amount of previous traffic over link can be measured. Therefore, this is the motivation of our proposed algorithm, the D-PPL. The D-PPL algorithm is improved based on the R-PPL routing algorithm by integrating traffic-per-link parameters. The parameters are periodically updated and are dynamically changed depended on current incoming traffic. The D-PPL tries to reserve residual bandwidth to service future request by avoid routing through those high traffic-per-link parameters. We have developed extensive MATLAB simulator to evaluate performance of the D-PPL. From simulation results, the D-PPL improves performance of MPLS on-line routing in terms of rejection probability and total throughput.

• 한국지능시스템학회논문지
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• 제15권6호
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• pp.736-741
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• 2005

다단계 호핑(multi-hop) 무선 센서네트워크의 라우팅 경로를 설정하는데 있어서 데이터 전송의 요구가 있는 경우에만 경로를 만드는 Demand-Driven 방식의 대표적인 방법이 DSR(Dynamic Source Routing)인데 라우트 레코드를 패킷에 실어 보내기 때문에 이 또한 센서노드들의 수가 많아질수록 패킷이 무거워질 수밖에 없다. 본 논문에서는 DSR 프로토콜을 기반하면서도 라우팅 테이블을 적절히 이용하여 노드 수 증가에 대해 고정된 패킷크기를 가지도록 하였으며 라우팅 비용함수를 적용하여 각 센서노드들의 전원 소모량, 이동성(Mobility), 네트워크 내에서의 Traffic, 거리(Hop) 등을 복합적으로 고려한 안정적이고 신뢰성 있는 최적의 라우팅 설정알고리즘을 제안한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.772-776
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• 2004

This paper proposes an interference avoidance approach for Constraint-Based Routing (CBR) algorithm in the Multi-Protocol Label Switching (MPLS) network. The MPLS network itself has a capability of integrating among any layer-3 protocols and any layer-2 protocols of the OSI model. It is based on the label switching technology, which is fast and flexible switching technique using pre-defined Label Switching Paths (LSPs). The MPLS network is a solution for the Traffic Engineering(TE), Quality of Service (QoS), Virtual Private Network (VPN), and Constraint-Based Routing (CBR) issues. According to the MPLS CBR, routing performance requirements are capability for on-line routing, high network throughput, high network utilization, high network scalability, fast rerouting performance, low percentage of call-setup request blocking, and low calculation complexity. There are many previously proposed algorithms such as minimum hop (MH) algorithm, widest shortest path (WSP) algorithm, and minimum interference routing algorithm (MIRA). The MIRA algorithm is currently seemed to be the best solution for the MPLS routing problem in case of selecting a path with minimum interference level. It achieves lower call-setup request blocking, lower interference level, higher network utilization and higher network throughput. However, it suffers from routing calculation complexity which makes it difficult to real task implementation. In this paper, there are three objectives for routing algorithm design, which are minimizing interference levels with other source-destination node pairs, minimizing resource usage by selecting a minimum hop path first, and reducing calculation complexity. The proposed CBR algorithm is based on power factor calculation of total amount of possible path per link and the residual bandwidth in the network. A path with high power factor should be considered as minimum interference path and should be selected for path setup. With the proposed algorithm, all of the three objectives are attained and the approach of selection of a high power factor path could minimize interference level among all source-destination node pairs. The approach of selection of a shortest path from many equal power factor paths approach could minimize the usage of network resource. Then the network has higher resource reservation for future call-setup request. Moreover, the calculation of possible path per link (or interference level indicator) is run only whenever the network topology has been changed. Hence, this approach could reduce routing calculation complexity. The simulation results show that the proposed algorithm has good performance over high network utilization, low call-setup blocking percentage and low routing computation complexity.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.1264-1266
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• 2009

We introduce a location-based routing model applied for grid backbone nodes in wireless mesh network. The number of paths with nearest distance between two nodes is calculated and used as key parameter to execute routing algorithm. Node will increase the transmission range that makes a trade off with data rate to reach its neighbors when node itself is isolated. The routing model is lightweight and oriented thanks to the simple but efficient routing algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권6호
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• pp.1063-1079
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• 2010

Vehicle ad hoc networks (VANET) are one of the most important technologies to provide various ITS services. While VANET requires rapid and reliable transmission, packet transmission in VANET is unstable because of high mobility. Many routing protocols have been proposed and assessed to improve the efficiency of VANET. However, topology-based routing protocols generate heavy overhead and long delay, and position-based routing protocols have frequent packet loss due to inaccurate node position. In this paper, we propose a position-based routing repair algorithm to improve the efficiency of VANET. This algorithm is proposed based on the premise that AODV (-PGB) can be used effectively in VANET, if the discovery, maintenance and repair mechanism of AODV is optimized for the features of VANET. The main focus of this algorithm is that the relay node can determine whether its alternative node exits and judge whether the routing path is disconnected. If the relay node is about to swerve from the routing path in a multi-hop network, the node recognizes the possibility of path loss based on a defined critical domain. The node then transmits a handover packet to the next hop node, alternative nodes and previous node. The next node repairs the alternative path before path loss occurs to maintain connectivity and provide seamless service. We simulated protocols using both the ideal traffic model and the realistic traffic model to assess the proposed algorithm. The result shows that the protocols that include the proposed algorithm have fewer path losses, lower overhead, shorter delay and higher data throughput compared with other protocols in VANET.