• Journal of the Korea Society of Computer and Information
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• v.19 no.1
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• pp.31-41
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• 2014

This paper proposes a virtual mobile ad-hoc network (VMANET) model that automatically divides heterogeneous mobile devices of a MANET into a number of network groups depending on the communication capacity(data rate) of different network operational models such as IEEE 802.11g, IEEE 802.11b, and Frequency Hopping. In addition, it supports a distinct routing protocol for each network group of VMANETs, resulting in running multiple routing protocols concurrently on different groups of VMANETs. To reduce the network congestion and improve the network load balance, a default MANET gateway is configured in each VMANET and these gateways are responsible for integrating the MANET and IP networks. Experiment results show that the proposed model outperforms the conventional IMANET by significantly increasing throughput and reducing network congestion and network delay.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.845-851
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• 2019

We design, implement, and evaluate a user-level ad hoc network routing protocol on the COTS (commercial off-the-shelf) mobile devices. In situations such as disaster recovery, emergency communication between mobile devices is necessary. For wide deployability and usability of such a system, we design and implement the networking protocols on the user level instead of modifying the kernel of mobile devices. In order to support reliable data transfer in high mobility scenarios, we selected to implement AODV (Ad Hoc On-Demand Distance Vector) as the routing protocol and TCP as the transport layer protocol. With our implementation of ad hoc networking stack on COTS smartphones, we conducted experiments in various networking environments. Our experimental results show that ad hoc networking is possible in up to 12 hops in a line topology and 5 concurrent devices in a star topology.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.103-109
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• 2013

Mobile ad hoc networks (MANETs) are infrastructure-less and stand-alone wireless networks with dynamic topologies. To support user's safety in MANETs, fundamental and various security services should be supported. Especially in mobile commercial market, one of the major concerns regarding security is user privacy. Recently, researches about security system to protect user privacy in cluster-based MANETs have been introduced. This paper propose a cluster reconfiguration protocol under anonymous cluster-based MANETs to enhance the network stability. The improved anonymous cluster-based MANETs can recover the network structure against abnormal states of clutserheads.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.40-48
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• 2008

Security of self organized mobile ad hoc networks is an important issue because administration information in the networks is managed by the constituent nodes. Especially authentication mechanism is necessary for trust setup between newly joining nodes and the network. The authentication models and protocols which are based on the wireline infrastructure could not be practical for mobile ad hoc network. Although public key algorithm-based method is widely used for authentication, it is not easy to be applied to mobile ad hoc networks because they do not have infrastructure such as centralized CA which is needed for certificate verification. In this paper, we consider the public key based random CA group method proposed in [1] to provide efficient authentication scheme to mobile ad hoc networks and analyze the performance of the method, which is then compared to the home CA method. From the analysis results, we see that the random CA method where the function of CA is distributed to some mobile nodes and the authentication information is propagated to randomly chosen CAs shows higher reliability and lower cost than home CA method.

• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.843-846
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• 2007

유비쿼터스 컴퓨팅 환경을 지원하기 위한 네트워크 환경은 점차 복잡해지고 다양화 되었다. 이러한 네트워크 환경은 기존의 환경과는 다르게 네트워크를 임시적으로 구성하는 애드혹 환경으로 변화하고 있다. 본 논문에서는 애드혹 네트워크를 지원하는 에이전트 관리 기능을 제안한다. 구현된 주요 기능은 모바일 장치간 에이전트 서비스 제공, 동적인 AMS, DF 서비스 제공자 생성, 서비스 제공자의 유지이며, 이러한 기능들은 블루투스(Bluetooth) 프로토콜을 기반으로 구현되었다. 이를 통해 기존의 에이전트 플랫폼에서 제공하지 못하는 애드혹 네트워크 환경 하의 에이전트 관리가 효율적으로 이루어짐을 확인할 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.8
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• pp.22-33
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• 2009

Mobile Ad Hoc Networks (MANETs) are self-organized networks that do not rely in their operation on wired infrastructure. As in any networking technology, security is an essential element in MANET as well, for proliferation of this type of networks. But supporting secure communication in MANETs proved to be a significant challenge, mainly due to the fact that the set of nodes in the network can change frequently and rapidly and due to the lack of access to the wired infrastructure. In particular, the trust model and the authentication protocols, which were developed for wired and infrastructure-based networks, cannot be used in MANETs. In [1], we addressed the problem of efficient authentication of distributed mobile users in geographically large networks and proposed a new authentication scheme for this case of MANETs. The proposed scheme exploits randomized groups to efficiently share authentication information among nodes that together implement the function of a distributive Certification Authority(CA). In this paper, we analyze numerically the performance of authentication method using randomized groups and compare with the simulation result.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.659-672
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• 2004

A Mobile Ad hoc Network (MANET) is a group of independent mobile computing nodes that consist of a multi-hop wireless network without a central administration or any infrastructure. Every node that wants to join a MANET must obtain an address for communication. Having a centralized DHCP server that provides addresses to nodes, we can easily and automatically obtain addresses. However, a MANET lacks any fixed infrastructure such as a DHCP server. We therefore propose a distributed address autoconfiguration approach for a MANET using a reserved address and optimistic Duplicated Address Detection (DAD). The reserved address helps to reduce the allocation latency, and the optimistic DAD guarantees the uniqueness of addresses and lessens communication overhead. We then suggest methods of handling network partition and network merging situations, and go on to evaluate our approach through simulations. The simulation result shows that our scheme guarantees the uniqueness of allocated address and considerably improves allocation latency and communication overheads.

• The KIPS Transactions:PartC
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• v.17C no.4
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• pp.379-384
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• 2010

Mobile nodes in high mobility ad hoc networks might come together in specific areas. In non-uniformly distributed networks, traffic load can be concentrated to intermediate nodes between dense clusters, and networks performance can be degraded. In this paper, we proposed a cluster based routing protocol that heavy traffic nodes adaptively react according to traffic load. The simulation result shows that the proposed protocol reduce packet loss and end-to-end delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.444-446
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• 2021

MANETs(Mobile Ad-hoc Networks) are composed of mobile nodes that are not subordinate to fixed networks and have the feature that can form their own networks. they are used in various fields for specific goals. The mobility model in MANET can be applied in various ways depending on the purpose of usage. The random mobility model has the advantage of being simple and easy to implement, so it is being used the most. In a MANET, it is assumed that each node moves independently. The random movement model is a good model for expressing this independence of each node. However, it is insufficient to express the characteristics of all nodes with only random properties of individual nodes. This paper limits the stochastic mobility model applicable in MANET. we compare the proposed stochastic mobility model and the random mobility model. We confirm that the proposed mobility model is applied to the routing protocol to show improved characteristics in terms of energy consumption efficiency.