• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.555-557
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• 2000

본 논문에서는 에드 혹 망의 멀티캐스트 라우팅 프로토콜인 ODMRP(On-Demand Multicast Routing Protocol)를 확장한 PatchODMRP를 제안한다. ODMRP는 멀티캐스트그룹의 송신원으로부터 수신원에 이르는 경로 상에 있는 노드들을 FG(Forwarding Group) 노드로 선출하여, 멀티캐스트 그룹 데이터 전송을 담당하는 메쉬를 구성하는 방법이다. 그런데 ODMRP는 주기적으로 이 메쉬를 구성하는 FG 노드들을 재선정하기 때문에 이 주기가 길어지면 메쉬 구성이 네트워크 노드들의 이동성을 따라가지 못해 메쉬 분리가 발생하고 데이터가 손실될 수 있다. 반면에 이 주기가 짧게 하면 오버헤드가 지나치게 커질 수 있다. 특히, 송신원의 수가 적은 경우 ODMRP의 메쉬는 매우 성기게 형성되는데, 이 때 호스트들의 이동성이 크면 메쉬 연결을 유지하기 위하여 이 주기를 짧게 잡아주거나, 높은 데이터 손실율을 감수해야 한다. 본 논문에서는 이 문제점을 해결하고자 각 FG 노드들이 BEACON 신호를 이용해 자신에 인접한 메쉬에 손실이 발생한 것을 인지하고 이를 국부적인 플러딩을 통하여 빠르게 복구하고 메커니즘을 ODMRP에 추가한 PatchODMRP 방식을 제안한다. 시뮬레이션을 통하여 기존의 ODMRP와 제안하는 ParchODMRP의 성능을 비교한 결과, ParchODMRP가 호스트의 이동성에 훨씬 강하며, ODMRP에 비하여 낮은 오버헤드로 높은 데이터 전달율을 제공할 수 있음을 보여주었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1186-1189
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• 2009

본 논문에서는 이동 애드 혹 네트워크의 성능 개선을 위한 방안으로 네트워크 중간에 고정 노드를 부가하여 어느 정도의 성능 향상이 있는지를 모의 실험을 통하여 평가하였다. 모의 실험 결과 이동 노드만을 사용했을 경우보다 고정노드를 함께 사용했을 때의 성능이 더 뛰어남을 알 수 있었고, 이동 노드의 이동 속도에 따른 비교에서도 고정 노드를 함께 사용한 경우가 성능이 더 뛰어남을 확인할 수 있었다. 또한 고정 노드의 개수에 따른 성능평가에서는 고정 노드를 여러 대 사용할수록 지연시간이 단축됨을 확인 할 수 있었다. 본 연구에서 제안한 방식은 이동 애드 혹 네트워크의 중간에 고정 노드를 부가하여야 하는 문제가 있으나, 비용과 처리율과의 관계를 비교한 후 비용 상승에도 불구하고 보다 높은 신뢰성과 빠른 처리율을 원하는 네트워크에 사용하면 효과적일 것이다. 향 후 본 절의 연구 결과에 이어서 애드 혹 네트워크에 몇 대의 고정 노드를 추가해야 하는지에 대한 연구가 이루어진다면 보다 높은 신뢰성을 가진 애드 혹 네트워크가 구축될 수 있을 것이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.658-667
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• 2009

NEMO (Network Mobility) introduces the concept of mobile router in order to supply users with group mobility over wireless and mobile networks. This paper investigates the advantages and disadvantages of NEMO in terms of the overhead of group mobility management. This paper proposes the additional requirements to enhance NEMO performance. Moreover, we analyze the main communication paths, CN-HA, HA-MR, and MR-MNN, in the real NEMO testbed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.113-115
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• 2015

In this paper, we proposed an algorithm based on movement prediction using rate of change of the attribute information of nodes what is called WRC(Weighted Rate Control) in delay tolerant networks(DTNs). Existing DTN routing algorithms based on movement prediction communicate by selecting relay nodes increasing connectivity with destination node. Thus, because the mobile nodes are in flux, the prediction algorithms that do not reflect the newest attribute information of node decrease reliability. In this paper, proposed algorithm approximate speed and direction of attribute information of node and analysis rate of change of attribute information of node. Then, it predict movement path of node using proposed weight. As the result, proposed algorithm show that network overhead and transmission delay time decreased by predicting movement path of node.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.171-178
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• 2007

In mobile ad hoc networks, an application scenario requires mostly group mobility behavior in the mix of group moving nodes and individually moving nodes. The nodes of those applications tend to belong to the movement group with similar movement behavior. Group mobility is one of the good methods to improve scalability, and reduces the protocol overhead. In this paper, we propose the multicast architecture which regards nodes that have equal group mobility in the heterogeneous group mobility network as the single entity with the multiple interfaces and composes multicast tree, The logical cooperative entity-based multicast architecture accommodates the scalability, the multicast tree simplification, and the protocol overhead reduction which arc obtained from the hierarchical multicast architecture, while it maintains the nat multicast architecture for the data transmission. It also prevents the concentration of the energy consumption dispersing data forwarding load into the several ingress/egress nodes. Results obtained through simulations show that logical cooperative entity based multicast protocol with multiple interfaces offers the protocol scalability and the efficient data transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.659-667
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• 2009

Mobile Ad-hoc Network consists of mobile nodes without immobile base station. In mobile ad-hoc network, network cutting has occurred frequently in node because of energy restriction and frequent transfer of node. Therefore, it requires research for certain techniques that react softly in topology alteration in order to improve reliability of transmission path. This paper proposes path selection techniques to consider mobility of node that respond when search path using AOMDV routing protocol. As applying proposed techniques, We can improve reliability and reduce re-searching number of times caused by path cutting.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.204-211
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• 2009

Proxy Mobile IPv6(PMIPv6) is that network-based mobility management protocol that network supports mobile node's mobility on behalf of the Mobile Node(MN). In PMIPv6 network, data packets from a Correspondent Node(CN) to a MN will always traverse the MN's Local Mobility Anchor(LMA). Even though, CN and MN might be located close to each other or within the same PMIPv6 domain. To solve this problem, several PMIPv6 Route Optimization(RO) schemes have been proposed. However, these RO schemes may result in a high signaling cost when MN moves frequently between MAGs. For this reason, we propose an adaptive route optimization(ARO) scheme. We analyze the performance of the ARO. Analytical results indicate that the ARO outperforms previous schemes in terms of signaling overhead.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.425-426
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• 2016

In this paper, we proposed an algorithm based on movement prediction using Markov chain in delay tolerant networks(DTNs). The existing prediction algorithms require additional information such as a node's schedule and connectivity between nodes. However, network reliability is lowered when additional information is unknown. To solve this problem, we proposed an algorithm for predicting a movement path of the node by using Markov chain. The proposed algorithm maps speed and direction for a node into state, and predict movement path of the node using transition probability matrix generated by Markov chain. As the result, proposed algorithm show that the proposed algorithms has competitive delivery ratio but with less average latency.

• Smart Media Journal
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• v.5 no.1
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• pp.55-60
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• 2016

Mobility of the sensor networks proposed a new way to the efficient design of sensor networks and improvement of network system performance. Mobility results in a number of functional changes in the MAC protocol and routing protocol. Especially, the mobility of the nodes may occur the increase of the overhead of transmission or disconnection of the link. Therefore, the study of the energy efficient transmission is very important in mobile sensor networks. This paper proposed adaptive transmission mechanism on the distance-based power control. The proposed mechanism was analyzed better than conventional method in the average energy consumption and network life by simulation results.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.9-16
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• 2008

The sink mobility can request frequent routing change in sensor networks. By active mobility a sink can gather needed information easily so that the network availability will be higher. However, instead static sink system, the connection between sensor nodes and a mobile sink can be changed continuously. That is, the rerouting should be implemented caused by the routing alteration. It is two connection setups for the mobile sink system: the connection from sink to sensor nodes and the connection from sensor nodes to sink. However, sensor nodes actually have many functional limitations. Hence, the low cost scheme will be needed for the connection setup from sensor nodes to the mobile sink. In this paper, we propose an agent scheme to the connection setup from sensor nodes to the mobile sink. The agent scheme provides the reliable setup scheme to the connection by using an agent sector.