• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.465-470
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• 2010

In this paper we propose a method which can be used to enhance the reliability of E-ODMRP (Enhanced On-Demand Multicast Routing Protocol). E-ODMRP has low overhead compared to its predecessors since it performs periodic refresh at a rate dynamically adapted to the nodes' mobility and adopts the local recovery. Upon detecting a broken route, a node performs a local search to graft to the forwarding mesh proactively. However in E-ODMRP there is no packet recovery mechanism. A receiver may lose some packets when it is detached from the multicast tree. We propose a simple packet recovery mechanism that can be incorporated into E-ODMRP for enhanced reliability. We show via simulation that our mechanism effectively enhances the reliability of E-ODMRP.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.997-1000
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• 2000

무선 인터넷 서비스에 대한 요구가 무선기술의 발전과 더불어 증가되고 있다. 하지만 현재의 인터넷 프로토콜인 IPv4에서는 IP의 이동 환경을 지원하지 못한다. 이에 여러 연구가 진행되고 있으며, IETF의 Mobile IP Working Group에서는 기존의 IPv4를 사용하면서도 이동환경을 지원하기 위한 이동 IP에 대한 연구를 진행하고 있다. 이에 본 논문에서는 인터넷에서 계층적이며 효율적인 이동성 지원을 위하여 영역과 도메인, 인터 도메인으로 세분화된 환경에서의 이동성 지원을 위한 기법을 제안한다. 본 논문에서는 하나의 이동 호스트가 특정 멀티캐스트 주소로 인식되어 멀티캐스트 라우팅 프로토콜에 의한 데이터 전송 서비스를 받는다. 이에 지속적인 이동성을 가진 이동 호스트에게 절단점 없는 서비스를 제공하기 위하여 동적 멀티캐스트 경로를 재설정 함으로서 경로 설정에 의한 오버헤드와 데이터전송의 지연을 최소화한다. 이러한 방법은 영역과 도메인, 인터 도메인의 계층적인 이동성을 지원함으로서 핸드오프 지연을 감소시키며. 홈 에이전트와 대응 노드에 부가되는 부하를 줄 일 수 있다.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.535-542
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• 2005

This paper proposes an on-demand ad hoc routing protocol, Node Density Based Routing (NDBR), which enhances the routing performance applying a new method to establish alternate patlis. It is important to reserve alternate paths for the route from source to destination in mobile ad hoc networks that are susceptible to failure due to the movement or the power exhaustion of mobile nodes. NDBR aims to establish a route that contains more alternate paths toward the destination by involving intermediate nodes with relatively more adjacent nodes in a possible route, and introduces a new routing criterion called 'node density.' This approach can localize the effects of route failures, and reduce control traffic overhead and route reconfiguration time by enhancing the reachability to the destination node without source-initiated route re-discoveries at route failures. This paper describes the route setup procedure using node density and the route re-configuration procedures employing alternate path information at the intermediate nodes. We show the performance of our routing schemes through a series of simulations using the Network Simulator 2 (ns-2).

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.3
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• pp.73-78
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• 2019

Due to frequent topology changes in wireless networks, inter-node link disconnection and path re-establishment occur, causing problems such as overloading control messages in the network. In this paper, to solve the problems such as link disconnection and control message overload, we perform path setup in three steps of the neighbor node discovery process, the route discovery process, and the route management process in the wireless network environment. The link stability value is calculated using the information of the routing table. Then, when the zone master monitors the calculated link value and becomes less than the threshold value, it predicts the link disconnection and performs the path reset to the corresponding transmitting and receiving node. The proposed scheme shows a performance improvement over the existing OLSR protocol in terms of data throughput, average path setup time, and data throughput depending on the speed of the mobile node as the number of mobile nodes changes.

• 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.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.583-588
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• 2007

It is easy to implement a temporary network with a mobile ad-hoc network in which mobile nodes have without using a infrastructure network. They depend on their limited power. Recently, it is a hot issue to save the energy in a mobile ad-hoc network because a mobile nodes have a limited energy. Research of IEEE 802.11 PSM was proposed in a single hop ad-hoc assumption. If IEEE 802.11 PSM is applied to multi hop ad-hoc network, non-optimal paths will be generated by the mobile nodes which didn't receive a message of routing request. Non-optimal paths increase not only a network latency but also energy consumption of mobile nodes. Reconfiguring algorithm of non-optimal paths caused by the mobile nodes which didn't receive a message of routing request is proposed in this paper. A mobile node can overhear the data in his range. A wireless medium is shared by all mobile nodes using the same bandwidth. All mobile nodes lookout the non-optimal paths with these properties of a medium, if non-optimal path is generated, optimal reconfiguring will be accomplished by modifying routing table of itself or sending a request message of routing update to nearby nodes. By reconfiguring the non-optimal paths to optimized ones, network latency and energy consumption was decreased. It is confirmed to ignore the overhead caused by a algorithm presented in this paper through the result of the simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.199-206
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• 2008

In this paper, we propose a novel Route_Reconf message as the RSVP message to maintain an RSVP session for hard handoff and consider path-comparing route (PCR) a PCR algorithm to find an intermediate node in the charge of downlink re-establishment. And, we consider information form each mode for the PCR algorithm, which also reduces the frequency and amount of exchanged RSVP message to minimize packet loss and delay between an intermediate node and a receiver. According to the proposed algorithm, a new support node (NSN) and an existing support node (ESN) along the RSVP path can be found; the former is a supporting RSVP session node newly searched and the latter is the last supporting node holding the previous session after handoff. On receiving the Route_Reconf message at the ESN, a new allocated route from a NSN to the MN waiting for the handoff via a new AR is configured by the ESN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.296-303
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• 2008

In this paper, we propose a novel Route_Reconf message as the RSVP message to maintain an RSVP session for hard handoff and consider a path-comparing route(PCR) algorithm to find an intermediate node in the charge of down-link re-establishment. And, we consider information form each mode for the PCR algorithm, which also reduces the frequency and amount of exchanged RSVP message to minimize packet loss and delay between an intermediate node and a receiver. According to the proposed algorithm, a new support node(NSN) and an existing support node(ESN) along the RSVP path can be found; the former is a supporting RSVP session node newly searched and the latter is the last supporting node holding the previous session after handoff. On receiving the Route_Reconf message at the ESN, a new allocated route from a NSN to the MN waiting for the handoff via a new access router is configured by the ESN.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.517-519
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• 2011

WSN 환경은 센서 노드에서 싱크 노드로 센싱 정보의 전송시 특정 센서 노드나 심지어는 하나의 센서노드의 과부하로 인해 전체 센서 네트워크에 문제를 야기시키며, 과다한 센싱 정보 트래픽 발생 및 동적 토폴로지 변화에 따라 빈번한 데이터 손실이 발생하게 된다. 본 논문에서 제안하는 VSDR(Visualization Sensing Data Routing)은 GML 기반 지도에 센서 노드 간 패킷 이동 경로와 전송되는 패킷 트래픽 전송량을 가시화한다. 또한, VSDR은 센서 네트워크에서 발생하는 센싱 정보들의 오버헤드와 센서 노드의 고장 발생 시 동적으로 데이터 경로들을 재설정 메커니즘을 제안한다.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1347-1355
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• 2007

A sensor network is composed of a large number of tiny devices, scattered and deployed in a specified regions. Each sensing device has processing and wireless communication capabilities, which enable it to gather information from the sensing area and to transfer report messages to a base station. The energy-efficient routing paths are established when the base station requests a query, since each node has several characteristics such as low-power, constrained energy, and limited capacity. The established paths are recovered while minimizing the total transmit energy and maximizing the network lifetime when the paths are broken. In this paper, we propose a routing algorithm that each sensor node reports its adjacent link information to the sink node when a sink node broadcasts a query. The sink node manages the total topology and establishes routing paths. This algorithm has a benefit to find an alternative path by reducing the negotiating messages for establishing paths when the established paths are broken. To reduce the overhead of collection information, each node has a link information before reporting to the sink. Because the node recognizes which nodes are adjacent. The proposed algorithm reduces the number of required messages, because sensor nodes receive and report routing messages for establishment at the beginning of configuring routing paths, since each node keeps topology information to establish a routing path, which is useful to report sensing tasks in monitoring environments.