• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.50-67
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• 2015

The Cognitive Radio (CR) paradigm in tactical ad hoc networks is an important element of future military communications for network-centric warfare. This paper presents a novel Cognitive Link State Routing protocol for CR-based tactical ad hoc networks. The proposed scheme provides prompt and reliable routes for Primary User (PU) activity through procedures that incorporate two main functions: PU-aware power adaptation and channel switching. For the PU-aware power adaptation, closer multipoint relay nodes are selected to prevent network partition and ensure successful PU communication. The PU-aware channel switching is proactively conducted using control messages to switch to a new available channel based on a common channel list. Our simulation study based on the ns-3 simulator demonstrates that the proposed routing scheme delivers significantly improved performance in terms of average end-to-end delay, jitter, and packet delivery ratio.

• Convergence Security Journal
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• v.7 no.3
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• pp.71-78
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• 2007

We proposed a simple and efficient routing protocol designed specifically for multi-hop ad-hoc networks. The proposed protocol is composed of the two routing tables which work together to allow nodes to send and receive packets. All aspects of the protocol can be operated on networks entirely consisting bidirectional links and networks with unidirectional links. Finding unidirectional link is embedded in the routing protocol since we considered not only bidirectional links but also unidirectional links when we developed a routing method.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.67-70
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• 2002

본 논문은 IIPv6 기반의 Mobile Ad-hoc Networks 환경에서 화상회의 도구 같은 멀티캐스트 응용을 서비스하는데 이용될 수 있는 IPv6 기반의 자동네트워킹 기술을 제시한다. IPv6 유니캐스트 자동설정 기능을 이용하여 이동단말의 유니캐스트 주소를 자동으로 설정할 수 있고, 멀티캐스트 자동설정 기능을 이용하여 멀티캐스트 주소 할당을 필요로 하는 응용에게 멀티캐스트 주소를 쉽게 할당할 수 있으므로 Mobile Ad-hoc Networks 환경에서의 사용자는 이러한 자동네트워킹 기술을 통해 멀티 캐스트 서비스를 쉽게 이용할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.92-101
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• 2012

Security support is a significant factor in ad hoc networks. Especially in dynamic topologies, key agreement with private key updating is essential in providing a secure system. And it is also necessary to protect the identities of individual nodes in wireless environments to avoid personal privacy problems. However, many of the existing key agreement schemes for ad hoc networks do not consider these issues concurrently. This paper proposes an anonymous ID-based private key update scheme and a key agreement scheme for mobile ad hoc networks. We also suggest a method of rekeying between different domains using service-coordinators. These schemes are secure against various attacks and are suitable for service-oriented mobile ad hoc networks.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.974-987
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• 2005

As the ad hoc networks have been received a great deal of attention to not only the military but also the industry applications, some security mechanisms are required for implementing a practical ad hoc application. In this paper, we propose a security architecture in ad hoc networks for the purpose of supporting ID-based public key cryptosystems because of the advantage that ID-based schemes require less complex infrastructure compared with the traditional public key cryptosystems. We assume a trusted key generation center which only issues a private key derived from IDs of every nodes in the system setup phase, and use NIL(Node ID List) and NRL(Node Revocation List) in order to distribute the information about IDs used as public keys in our system. Furthermore, we propose a collaborative status checking mechanism that is performed by nodes themselves not by a central server in ad-hoc network to check the validity of the IDs.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.121-127
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• 2009

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, we simulate and compare the performance of conventional single and cooperative spectrum sensing with CR system using ad-hoc networks. And we demonstrate performance improvement by analyzing the system performance.

• Journal of Communications and Networks
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• v.11 no.2
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• pp.187-195
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• 2009

The application of mathematical analysis to the study of wireless ad hoc networks has met with limited success due to the complexity of mobility, traffic models and the dynamic topology. A scenario based universal mobile telecommunications system (UMTS) time division duplex (TDD) opportunistic cellular system with an ad hoc behaviour that operates over UMTS frequency division duplex (FDD) licensed cellular network is considered. In this paper, we present a new routing metric which overall improves system performance in terms of interference and routing which operate in an ad hoc network in an opportunistic manner. Therefore we develop a simulation tool that addresses the goal of analysis and assessment of UMTS TDD opportunistic radio system with ad hoc behavior in coexistence with a UMTS FDD primary cellular networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.507-513
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• 2007

In this paper, we propose an efficient authentication protocol based on certificateless signature scheme, which does not need anyinfrastructure to deal with certification of public keys, among the vehicles in Vehicular Ad-hoc Networks. Moreover, due to the characteristicsof VANET nodes (i.e., vehicles) that is fast and movement, the proposed protocol introduces the concept of interval signing key to overcome efficiently the problem of certificate revocation in traditional Public Key Infrastructure(PKI).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.7 s.337
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• pp.7-18
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• 2005

Geomulticast is a specialized location-dependent multicasting technique, where messages are multicast to some specific user groups within a specifc zone. In this paper, we propose architectures and protocols for supporting geomulticast services in a cost effective way and with high message delivery accuracy in the challenging environment of mobile ad-hoc networks. Furthermore, we define and formulate a framework in order to evaluate the performance of the design alternatives used for the support of geomulticast services in mobile ad-hoc networks. Based on this framework, we evaluate the performance of the proposed architectures and protocols and we obtain some insight about the impact of the various design and operational parameters on the overall system performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.31-39
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• 2011

In this paper, we propose an evenly distributed mesh scheme to support services in mobile ad-hoc networks. Two strategies, the adaptive upgrading of forwarding nodes and the adaptive downgrading of forwarding nodes, are presented in the scheme. Our proposed scheme can support construction of better multicast mesh that can give higher packet delivery ratio with lower duplicate data as well as solve the problem of serious congestion especially when node mobility and data transmission rate are high in mobile ad-hoc networks. The performance evaluation is performed via simulation using OPNET.