• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1196-1203
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• 2013

In general, the cost of transceiver for wireless network configuration is more expensive than that for wired network. However, in case of environmental management system in a tunnel, the cost can be minimized by adopting low rate tranceiver because the amount of the exchanged data for tunnel monitoring is very small. When the obtained data from sensor node is sent directly to the corresponding command node, there is no need to consider routing problem of the data transfer. However in this case, sensor nodes are required to be implemented with high power transmitter and experience high energy consumption. To tackle this problem, relay nodes can be used to transfer the data of tunnel monitoring, and suitable routing protocols for selecting optimum path are needed. Therefore, in this paper, we propose a routing algorithm and a self-configuration protocol for environment management system in tunnel.

• Journal of Communications and Networks
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• v.6 no.1
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• pp.60-67
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• 2004

With the fast growth of Internet and a new widespread interest in optical networks, the unparalleled potential of Multi-Protocol Label Switching (MPLS) is leading to further research and development efforts. One of those areas of research is Path Protection Mechanism. It is widely accepted that layer three protection and recovery mechanisms are too slow for today’s reliability requirements. Failure recovery latencies ranging from several seconds to minutes, for layer three routing protocols, have been widely reported. For this reason, a recovery mechanism at the MPLS layer capable of recovering from failed paths in 10’s of milliseconds has been sought. In light of this, several MPLS based protection mechanisms have been proposed, such as end-to-end path protection and local repair mechanism. Those mechanisms are designed for intra-domain recoveries and little or no attention has been given to the case of non-homogenous independent inter-domains. This paper presents a novel solution for the setup and maintenance of independent protection mechanisms within individual domains and merged at the domain boundaries. This innovative solution offers significant advantages including fast recovery across multiple nonhomogeneous domains and high scalability. Detailed setup and operation procedures are described. Finally, simulation results using OPNET are presented showing recovery times of a few milliseconds.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.116-123
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• 2013

In mobile healthcare applications, the reliable transmission of the bio-data is very important. In this article, we present a reliable bio-data transmission technique for mobile healthcare monitoring service at 6LoWPAN multi-hop wireless networks. In particular, we expand IEEE 11073-20601 protocol, and propose the reliable path construction for 6LoWPAN aimed to reliably provide mobile healthcare service over wireless sensor network, using IPv6 network. 6LoWPAN is recognized possibility because it is agree with sensor network by raising Adaptation layer on the MAC layer to transmit IPv6 packets. In this article proposed minimize the algorithm complexity and reliability routing protocol because the 6LoWPAN devices are suitable for low cost, small size and battery that can be used to health care system environment. And detailed procedures and algorithms are presented. We the proposed method to prove the superiority of using NS-3 for compareing with AODV protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2473-2492
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• 2012

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes' energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.100-109
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• 2005

A Mobile Ad-Hoc Network (MANET) supports a multi-hop wireless network without any prepared base station (BS). The MANET is capable of building a mobile network automatically without any help from DHCP servers for address allocation or routers to forward or route messages. Many routing protocols have been proposed for the MANET, but these specify the most optimized or shortest path from a source to a destination, and they assume that nodes are pre-configured before communication. To make up for this, address allocation algorithms, such as MANETConf [1] and prophet address allocation algorithm [2], have been proposed. Especially, MANETConf proposes address allocation algorithm with duplication address check. In this paper, we present a dynamic node configuration protocol based on 2-tierd hierarchical network architecture for mobile ad-hoc network, modified from [1]. Especially, it reduces the number of broadcast message exchange between nodes when a new node somes into a network, which lessens network overhead, remarkably. This protocol is based on two-tired structure, and it ensures address allocation with simple duplication address defection mechanism.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.645-653
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• 2014

Recently, the ocean field researches such as offshore plant, ocean survey and underwater monitoring systems are garnering the attention from both academy and industry. However, the communication in underwater environment is very difficult because of the unique irregular features in water. This is the reason that the application of terrestrial protocols to the water environment is not proper. This paper proposes a routing algorithm that can enhance communication reliability by utilizing channel properties in underwater environment. We address two problems that lead to the poor communication performance, signal attenuation and multi-path problem in water. Overcoming these problems, the proposed algorithm ensures high packet delivery ratio and low transmission delay. Also, this paper evaluates the performance through simulation.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.22-30
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• 2022

The reinforcement learning algorithm has proven its potential in solving sequential decision-making problems under uncertainties, such as finding paths to route data packets in wireless sensor networks. With reinforcement learning, the computation of the optimum path requires careful definition of the so-called reward function, which is defined as a linear function that aggregates multiple objective functions into a single objective to compute a numerical value (reward) to be maximized. In a typical defined linear reward function, the multiple objectives to be optimized are integrated in the form of a weighted sum with fixed weighting factors for all learning agents. This study proposes a reinforcement learning -based routing protocol for wireless sensor network, where different learning agents prioritize different objective goals by assigning weighting factors to the aggregated objectives of the reward function. We assign appropriate weighting factors to the objectives in the reward function of a sensor node according to its hop-count distance to the sink node. We expect this approach to enhance the effectiveness of multi-objective reinforcement learning for wireless sensor networks with a balanced trade-off among competing parameters. Furthermore, we propose SDN (Software Defined Networks) architecture with multiple controllers for constant network monitoring to allow learning agents to adapt according to the dynamics of the network conditions. Simulation results show that our proposed scheme enhances the performance of wireless sensor network under varied conditions, such as the node density and traffic intensity, with a good trade-off among competing performance metrics.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.46-53
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• 2012

The traffic in research network for the new structure of the network and new service research has the various properties. From the perspective of a specific traffic point of view, transmission of traffic with different requirements using a single routing protocol is an obstacle to satisfy requirements. In this study, we classify the properties of the traffic into two types. We propose the way that we can get the overall optimization effect, the experiment proves it by providing independent multiple forwarding path by applying optimized algorithm by types. In order to distinguish each type of traffic we use the ports on the switch and in order to implement independent path we apply OpenFlow system. In other words, we present the measure that can be implemented to improve the satisfaction of the traffic by making multiple paths by OpenFlow controller according to the type of traffic and by enforcing in Forwarder.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.623-626
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• 2010

최근 무선 네트워크 기술이 점차 각광을 받으면서 다양한 애드 혹 환경에서의 라우팅 프로토콜이 제안되고 있다. 하지만 애드 혹 네트워크라는 환경의 특성 상 보안상 취약한 문제점을 가지고 있으며, 기존의 유선 네트워크 환경에서 제안되었던 보안 라우팅 프로토콜을 적용시키기 힘들다는 문제점이 있다. 이에 따라 보안성을 보완한 새로운 애드 혹 라우팅 프로토콜이 제안되었지만 다양한 무선 네트워크 환경의 변화에 유동적으로 대응하기 힘들고 보안적인 측면에 집중을 한 나머지 에너지소모 측면에서는 단점을 노출하고 있다. 본 논문에서는 다양한 애드 혹 네트워크 환경에 적용 가능하고, 기존의 보안 라우팅 프로토콜에 비해 에너지 효율적인 보안 라우팅 프로토콜을 제안하고자 한다. 보안 정보의 보호를 위해 Tree 구조를 도입하고 보안 단계를 통한 Multi-path를 구성하여 악의적인 노드의 Dropping Attack에 대비하고, 예기치 못한 Data Packet의 손실에 대해서도 효율적으로 대처하게 하였다. 실험 결과 악의적인 노드가 존재하는 네트워크 환경에서 기존의 애드 혹 네트워크 보안 라우팅 프로토콜보다 21%정도의 패킷 전송 성공률을 높일 수 있었으며 또한 각 노드의 에너지를 균등하게 소모함으로써 전체적인 네트워크의 생존시간이 연장되는 것을 확인할 수 있었다.

• Journal of KIISE:Information Networking
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• v.31 no.3
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• pp.280-288
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• 2004

In Ad Hoc Networks, a connection breaks due to the irregular movement of mobile nodes and the inherent characteristics of the wireless medium such as the interference and the multi-path fading. AODV, a typical on-demand routing protocol in Ad Hoc networks, uses the local repair mechanism to cope with the connection breaks. This paper proposes an efficient route maintenance scheme for AODV, named as AODV-ERM, by utilizing hello messages. The proposed AODV-ERM scheme can recover some link breaks efficiently without relying on the expensive local repair process, thereby reducing the repair time. To show the effectiveness of the proposed scheme, we performed extensive simulation with NS2. The simulation results show that the proposed scheme can reduce the repair time effectively and thus, increase the overall packet delivery ratio.