• Journal of KIISE:Computing Practices and Letters
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• v.14 no.4
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• pp.352-362
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• 2008

In the mobile ad hoc network, network nodes are continuously capable of movement, but have battery limitations and these characteristics of MANET cause network link failure. Therefore, when performing ubiquitous services with the application of MANET, a technique is required to improve the packet transmission rates as to enable continuous packet transmission while flexibly adapting to topology changes caused by the mobility of nodes. In this paper, we are proposing PAOMDV(Possibility based AOMDV) and OLSR-ME(OLSR with Modified Energy Efficiency) which are mixed-type protocols to solve the problem for design a more efficient protocol. Especially by classifying mobile ad hoc networks as clusters, OLSR-ME protocol is implemented on communication within the clusters, while PAOMDV is used in protocols between clusters. In addition, a selection algorithm for forwarding nodes that responding packet relays in the case of increased hops was proposed for designing a more efficient protocol than existing protocols. We verified the performance of the proposed protocols through a comparative experiment with AODV, AOMDV, ZRP, and the existing protocols. We confirmed the results of the experiment revealed that the proposed protocol had the best packet transmission rate, the shortest delay between nodes, and showed better results in routing overhead.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.255-260
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• 2008

In the recently years, there has been a big interest in ad hoc wireless network as they have tremendous military and commercial potential. An Ad hoc wireless network is composed of mobile computing devices that use having no fixed infrastructure of a multi-hop wireless network formed. So, the fact that limited resource could support the network of robust, simple framework and energy conserving etc. In this paper, we propose a new ad hoc multicast routing protocol for based on the ontology scheme called inference network. Ontology knowledge-based is one of the structure of context-aware. And the ontology clustering adopts a tree structure to enhance resilient against mobility and routing complexity. This proposed multicast routing protocol utilizes node locality to be improve the flexible connectivity and stable mobility on local discovery routing and flooding discovery routing. Also attempts to improve route recovery efficiency and reduce data transmissions of context-awareness. We also provide simulation results to validate the model complexity. We have developed that proposed an algorithm have design multi-hierarchy layered networks to simulate a desired system.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.155-163
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• 2007

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 Destination sequence numbering for loop-free, but it may cause RREQ broadcast storm problem. This paper proposes AODV_ods that does not need destination sequence number, in routing message and routing table without routing loop. To show the effectiveness of the proposed scheme, we performed extensive simulation with NS-2. The simulation results show that the proposed ADOV_ods efficiently uses wireless bandwidth compare to the original AODV. Finally AODV ods reduces the routing overhead, end to end delay and increases the overall packet delivery ratio.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.263-267
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• 2011

이동 Ad-Hoc 네트워크는 고정된 기반 망의 도움 없이 이동 노드들 간에 자율적으로 구성되는 망으로서, 모바일 노드 자체적으로 연결이 설정된 무선 네트워크이다. 이러한 이동 Ad-Hoc 네트워크는 유선 네크워크에 비해 보안에 매우 취약하여 네트워크 가입자에 대한 인증과 이동 Ad-Hoc 네트워크에 대한 인증이 매우 취약하다. 또한 사용자의 식별이 보호되지 않는다. 본 논문에서 제안하는 인증 프로토콜은 모바일 네트워크 인증서버가 분배한 임시 인증서를 사용하여 사용자의 식별하고 인증한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.217-219
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• 2004

이동 Ad-hoc 네트워크(MANET) 환경은 기존의 서버/클라이언트 구조인 유선 네트워크와 달리 이동 노드만으로 구성된 네트워크로서, 노드들의 이동이 빈번하게 발생하는 매우 동적인 특성을 가지고 있다. 따라서 서버의 도움 없이 노드들 스스로 네트워크 토폴로지를 효과적으로 구성하고 이를 적절히 유지하는 기법이 요구된다. 본 논문에서는 메모리, 프로세싱, 베터리와 같은 노드 정보와 가용 대역폭, 서비스중인 노드의 수와 같은 네트워크 정보를 이용하어 적응적으로 네트워크 토폴로지를 구성하는 기법을 제시한다. 이 기법은 새로운 노드의 네트워크 참여 여부를 결정하는 토폴로지 디스커버리와 기존 노드의 탈퇴 및 위지 이동 등과 같은 상황에 적응적으로 대처하는 토폴로지 유지 기법으로 구성된다. 또한 기간망에 연결되지 않는 독립 Ad-hoc 네트워크와 기간망에 연결되는 통합 Ad-hoc 네트워크 간의 빠른 전환을 위한 네트워크 설정 자가 구성기법을 제시한다.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.231-234
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• 2003

In this paper, we propose the enhanced CSMA/CA MAC protocol fir mobile multi-hop wireless Ad-hoc networks. In the conventional wireless Ad-hoc network such as WLAN using CSMA/CA MAC protocol, communications between terminals that fn connected within multi-hop node may degrade the transmission efficiencies as increasing the multi-hop nodes because of RTS-CTS-DATA-ACK message exchange between terminals. In this raper, we apply the ACK/RTS control message into multi-hop transmission between terminals for wireless ad-hoc networks and improve the data traffic transmission efficiencies compared with conventional CSMA/CA MAC protocol used in WLAN.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1349-1352
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• 2002

최근의 컴퓨터와 인터넷 기술의 발달로 인해 시간과 장소에 제약을 받지 않는 네트워크를 구성하기 위한 연구가 활발히 진행되고 있다. 그 중 외부 네트워크로 연결이 힘든 상황에서의 네트워크를 구성하고자 하는 연구, 즉 외부와는 단절돼 있거나 외부와 독립적인 네트워크를 구성하고자 하는 모바일 Ad hoc 네트워크에 관한 연구이다. 본 논문에서는 이러한 모바일 Ad hoc 네트워크에서 서비스 탐색 시 네트워크의 자원을 불필요하게 많이 소모하는 브로드캐스트를 기반으로 한 기존 기법인 플러딩을 배제하고 동종의 서비스를 하나의 멀티캐스트 그룹으로 만든 후 서비스 탐색을 실시하는 방법을 제시하였다. 이러한 방법을 통해 모바일 Ad hoc 네트워크에서의 브로드캐스트를 줄이며, 동시에 서비스를 효과적으로 받을 수 있는 가능성을 기술하고자 한다.

• 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).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.42-50
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• 2008

Unlike a cellular network, a mobile ad hoc network(MANET) is constructed only by mobile nodes without access point. Mobile nodes in MANET operate with scarce resources and restricted battery. If battery of intermediate node is exhausted, overall network might be diverged. Therefore, power-aware is really important. An on-demand multipath routing protocol which is proposed to compensate for shortcoming of on-demand single path routing protocol can reduce mute discovery overhead because route discovery starts only when all routes are disconnected. AOMDV(Ad hoc On-demand Multipath Distance Vector) which is on-demand multipath routing protocol based on AODV, reduces 40% of route discovery frequency. However, AOMDV have none of power-aware. So AOMDV have problem that route discovery for power exhaustion is not reduced at all. This paper proposes new power-aware path selection algorithm for AOMDV and scheme that broadcast REER packets when mobile node's battery can be gone. Performance comparison of proposed algorithm with AOMDV using ns-2 simulator shows that route discovery of proposed algorithm is reduced maximally 36.57% than AOMDV's.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1446-1459
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• 2008

In an infrastructure-based wireless network, an access point is used for all communications among mobile devices. However, when a mobile device moves into a dead Bone, a connectivity disruption between the mobile device and the access point occurs. Such connectivity disruption consequently leads to another connectivity disruption between the mobile device moving toward the dead zone and other wireless-enabled devices located within the area of the infrastructure-based wireless network. To cope with the connectivity disruption in the infrastructure-based wireless network the ad hoc network that dynamically forms a network without any preexisting communication infrastructure needs to be set up to provide seamless connections among mobile devices. In this paper, we propose the DNSQ-MAC (Dynamic Network State aware QoS-Medium Access Control) technique that meets the deadlines of MAC frames forwarded over hop-by-hop multipaths and guarantees the QoS performance of an ad hoc-based wireless network. Mobile devices incorporating the DNSQ-MAC technique are capable of adjusting to the new dynamic network status in order to enhance the QoS performance in the ad hoc-based wireless network. A case study which exploits the Qualnet simulator shows that the proposed DNSQ-MAC technique can guarantee the deadlines of MAC frames forwarded over hop-by-hop multipaths and enhance the QoS performance of various routing protocols and packet schedulers running on the network layer above the MAC layer.