• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.75-79
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• 2011

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 in additive white Gaussian noise (AWGN) and Rayleigh channel model. And we demonstrate performance improvement by analyzing the system performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.482-488
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• 2009

Mobile Ad-hoc Networks provide communication without a centralized infrastructure, which makes them suitable for communication in disaster areas or when quick deployment is needed. On the other hand, they are susceptible to malicious exploitation and have to face different challenges at different layers due to its open Ad-hoc network structure which lacks previous security measures. Denial of service (DoS) attack is one that interferes with the radio transmission channel causing a jamming attack. In this kind of attack, an attacker emits a signal that interrupts the energy of the packets causing many errors in the packet currently being transmitted. In harsh environments where there is constant traffic, a jamming attack causes serious problems; therefore measures to prevent these types of attacks are required. The objective of this paper is to carry out the simulation of the jamming attack on the nodes and determine the DoS attacks in OPNET so as to obtain better results. We have used effective anomaly detection system to detect the malicious behaviour of the jammer node and analyzed the results that deny channel access by jamming in the mobile Ad-hoc networks.

• Proceedings of the Safety Management and Science Conference
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• 2002.05a
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• pp.121-127
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• 2002

In this paper, we propose traffic management support and evaluate the performance through simulation. We suggest traffic management routing protocol that can guarantee reliance according to not only reduction of the Network traffic congestion but also distribution of the network load that prevents data transmission. For performance evaluation, we analyzed the average data reception rate and network load, considering the node mobility. We found that in the mobile Ad Hoc networks, the traffic management service increased the average data reception rate and reduced the network traffic congestion and network load in Mobile Ad Hoc Networks.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.1
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• pp.8-13
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• 2006

In mobile ad hoc networks, most of on demand routing protocols such as DSR and AODV do not deal with traffic load during the route discovery procedure. To achieve load balancing in networks, many protocols have been proposed. However, existing load balancing schemes do not consider the remaining available buffer size of the interface queue, which still results in buffer overflows by congestion in a certain node which has the least available buffer size in the route. To solve this problem, we propose a load balancing protocol called Dynamic Congestion Aware Routing Protocol (DCAR) which monitors the remaining buffer length of all nodes in routes and excludes a certain congested node during the route discovery procedure. We also propose two buffer threshold values to select an optimal route selection metric between the traffic load and the minimum hop count. Through simulation study, we compare DCAR with other on demand routing protocols and show that the proposed protocol is more efficient when a network is heavily loaded.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.5
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• pp.475-491
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• 2009

This paper is primarily concerned with multi-path routing in Mobile Ad hoc Networks (MANETs). We propose a novel associativity-based on-demand source routing protocol for MANETs that attempts to establish relatively stable path(s) between the source and the destination. We introduce a new notion for gauging the temporal and spatial stability of nodes, and hence the paths interconnecting them. The proposed protocol is compared with other unipath (DSDV and AODV) and multi-path (AOMDV) routing protocols. We investigate the performance in terms of throughput, normalized routing overhead, packet delivery ratio etc. All on-demand protocols show good performance in mobile environments with less traffic overhead compared to proactive approaches, but they are prone to longer end-to-end delays due to route discovery and maintenance.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.385-392
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• 2011

A loop can take place in the process of managing tree topology for mobility management of mobile nodes in infrastructure-based mobile ad hoc networks. The formation of a loop degrades an effective bandwidth of the wireless network by passing an identical message repeatedly within the same loop. Therefore, the loop should be resolved to revert the system back to the normal state. In this paper, we propose a simple and novel mechanism that detects and resolves a loop quickly by tracking the depth of trees. The mobility management approach that employs the loop resolution method is evaluated comparatively with the original tree-based one and the hybrid one. It is shown that the proposed approach far outperforms the other approaches, and it is robust against the rapid changes in network topology.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.160-161
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• 2013

Extending mobile IP to ad hoc networks with the foreign agent acting as the bridge between the wired network and ad hoc networks can provide the global Internet connectivity for ad hoc hosts. The existing research in the area of the integrated wired and ad hoc network is carried out in a non-adversarial setting. This paper analysed an effective solution to solve the security related problems encountered in these integrated networks. This security protocol also excludes malicious nodes from performing the ad hoc network routing. This paper focuses on preventing ad hoc hosts from the attacks of anti-integrity.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.553-555
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• 2003

Mobile Ad hoc network에서 이동 노드들의 안정적이고 신뢰성이 높은 데이터 전송을 하기 위해서 multipath routing을 통하여 소스 목적지 노드간에 다중 경로를 구하고 기존의 라우팅 방법과 비교해 본다. 또한 다중 경로를 활용하는 방법과 경로구간의 링크 다운 시에 보다 빠른 복원을 할 수 있는 방법을 제시하고자 한다. 모바일 노드들의 이동성과 낮은 대역폭으로 인한 데이터 손실을 줄이는 방법으로 데이터 트래픽을 다중경로에 분산시키는 Traffic Load Balancing 방법과 데이터 전송 중에 발생하는 링크 다운 시에 새로운 경로를 찾는 메커니즘이 아닌 중간 경로에서 기존에 유효한 경로를 이용하는 Local recovery 방법을 소개하고자 한다.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.627-633
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• 2008

In the case of traffic accidents, the broadcasting methods used in the mobile ad hoc network (MANET) cannot applied to transmit reliable message since moving high-speed in vehicular ad hoc networks (VANET) environments. In this paper, in order to guarantee transmitting reliable messages, we propose a collision avoidance method based-on directional antenna in VANET. In order to reduce interference from omni-broadcasting and to avoid hidden node problem from moving high-speed, we employed a forward-handed and backward directional antenna. The authors simulated the proposed method based on directional antenna and showed that the proposed method has been improved in respect to network utilization compared to existing VANET protocols.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.829-834
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• 2004

Nodes communicate through wireless channels under peer-to-peer level in ad-hoc mobile networks. The nodes are free to move around in a geographical area and are loose]y bounded by the transmission range of the wireless channels. Also, a node is completely free to move around, there is no fixed final topology. Hence, to manage the inter-node communication and data exchange among them a leader node is required. In this paper we introduce an efficient leader election algorithm for mobile ad hoc networks where inter-node communication is allowed only among the neighboring nodes. Furthermore we present the result of performance evaluation through simulation. The algorithm is efficient and practical since it uses least amount of wireless resources and does not affect the movement of the nodes.