• Journal of KIISE:Information Networking
• /
• v.32 no.3
• /
• pp.310-317
• /
• 2005

In opposition to conventional networks, mobile ad hoc networks usually do not offer trust about nodes or online access through certificate authorities or centralized servers. But, nodes in those systems need process that can search path as well as trust each other to exchange data in safety For these reasons, traditional security measures that require online trusted authorities or certificate storages are not well-suited for securing ad hoc networks. In this paper, I propose a secure and effective method to search the optimized path using profitable flooding techniques on certificate chains in MANETS(Mobile Ad hoc NETworks). This system includes not only using routing protocols that are generally broadcasting packets but also finding nodes securely and verifing the process through tiust relationships between nodes that are searched.

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

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10c
• /
• pp.250-252
• /
• 2004

애드 혹 네트워크는 기지국과 같은 통신 인프라가 없는 환경에서 이동 노드들 간에 통신이 가능한 망을 말한다. 최근 애드 혹 네트워크의 데이터 전송에 관한 연구가 활발히 이루어지면서 다양한 영역에 대한 연구들이 제안되고 있다. 그중 네임 서비스는 서비스를 이용하는 사용자가 IP 주소를 기억하기 어려움으로 인해 제안되었고 유선망에서는 DNS를 통해 네임 서비스를 제공하고 있다. 하지만, 애드 혹 네트워크에서는 노드들이 이동하고 임의로 만들어지는 특성으로 인해서 유선망과 같은 DNS 서버를 통해서 네임 서비스를 제공하기 어렵다.본 논문은 애드 혹 네트워크의 특성을 고려한 명시적인 MDNS(MANET oomain Name System) 서버를 이용하는 방법을 도입함으로써 애드 흑 네트워크에서 효율적인 네임 서비스를 제안하고자 한다.

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

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2009.01a
• /
• pp.279-282
• /
• 2009

유비쿼터스 센서 네트워크(USN)는 다수의 u-센서 노드간 애드 혹(Ad Hoc), 멀티 홉(Multi Hop) 통신으로 구성된다. 그러나 USN이 시작 단계인 현재 시점에서, 과거 시리얼이나 이더넷으로 구성된 유선 네트워크를 지그비, 블루투스, 와이파이 등을 이용한 포인트 투 포인트 (Point To Point) 무선 네트워크로 전환하는 이슈가 많은 부분을 차지하고 있다. 하지만 적용 범위가 넓고 별도의 광역 인프라를 구성하기 곤란한 경우, USN을 이용한 애드 흑, 멀티홉 메시 네트워크를 구성하는 사례도 점차 늘어나고 있다. 본 논문에서는 이러한 환경에서 유비쿼터스 센서 네트워크를 보다 쉽고 편리하게 모니터링 하기 위한 시스템을 제안하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.313-315
• /
• 2005

본 논문은 이동 애드혹 네트워크에서 이동 에이전트를 이용하여 동적으로 클러스터링을 구성하는 기법에 관한 것이다. 기존에 제안된 이동 애드혹 네트워크에서의 클러스터링 기법은 클러스터의 크기가 고정되어 있기 때문에 네트워크의 상태나 노드들의 이동성에 따라 클러스터 재구성의 오버헤드가 발생하였다. 본 제안 기법에서는 네트워크의 상태에 따라 클러스터 크기의 최대 임계치와 최소 임계치를 설정하고 이에 따라 이동 에이전트를 이용하여 클러스터를 병합 흑은 분할하면서 클러스터의 크기를 임계치 내에서 일정하게 유지시킴으로써, 클러스터 재구성의 오버헤드라 클러스터 내부의 경로 탐색의 오버헤드를 줄일 수 있다.

• Journal of KIISE:Information Networking
• /
• v.30 no.2
• /
• pp.252-259
• /
• 2003

In the case of link congestion, most of the existing ad-hoc routing protocols like AODV and DSR do not try to discover a new route if there is no change in the network topology. Hence, with low mobility, traffic may get concentrated on some specific nodes. Since mobile devices have low battery power and low computing capability, traffic concentration on a specific node is not a desirable phenomenon. Therefore, in this paper, we propose a new protocol called SLAP (Simple Load-balancing Ad-hoc routing Protocol) which resolves the traffic concentration problem by letting each node check its own load situation and give up its role as a packet forwarder gracefully in the case of high traffic load. We compare the performance of SLAP with that of AODV and DSR in terms of the forwarding traffic distribution.

• The KIPS Transactions:PartC
• /
• v.12C no.7 s.103
• /
• pp.1031-1038
• /
• 2005

As the research on home network technologies, sensor network technologies, and ubiquitous network technologies makes rapid progresses, wireless ad-hoc network have attracted a lot of attention. A wireless ad-hoc network is a temporary network formed by a collection of wireless mobile nodes without the aid of my existing network infrastructure or centralized administration, and it is suitable for ubiquitous computing environments. In this paper, we suggest an interconnection scheme between the wireless ad-hoc network environment based on multiple path source routing protocol and a Mobile-IP based network environment. This scheme reduces the overhead of route re-establishment and re-registration by maintaining multiple paths between the mobile host in wireless ad-hoc network and the base station in mobile-IP network. Also it puts the base station in charge of function that performs translation between wireless ad-hoc network packets and Mobile-IP packets, reducing the load of mobile hosts. In this paper, our simulations show that our scheme outperforms existing interconnecting schemes with regards to throughput and end-to-end delay Also we show that our scheme outperforms multi-paths approach using disjoint routes with regards to routing overhead.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.427-429
• /
• 2005

모바일 애드 흑 네트워크에서 않은 라우팅 프로토콜들이 연구되어지고 있다. 연구된 프로토콜 가운데 널리 쓰이고 있는 AODV는 On-Demand 방식으로써, 필요에 따라 라우팅 정보를 얻기 위한 메카니즘을 사용한다. 여기서 라우팅 정보를 얻은 이루에 링크 상태를 점검하기 위해서, Table-Driven 방식과 비슷하게 주기적으로 메시지를 전송함으로써 링크가 끊어질 경우의 상황을 인지 할 수 있도록 한다. 비록 On-Demand라 할지라도 주변에 노드들이 않으면, 라우팅의 유지를 위해 주기적으로 전송하는 패킷과 요구에 따른 라우팅 패킷으로 데이터를 전송하기 위한 대역폭에 영향물 줄 수 있다. 그래서 본 논문에서는 데이터를 전송하기 위한 채널과 제어/라우팅 정보를 교환하는 채널로 나누고 데이터를 전송하는데 있어서 신뢰성 있고 일정한 대역폭의 사용량을 줄 수 있는 방법을 제안한다.

• Journal of KIISE:Information Networking
• /
• v.33 no.1
• /
• pp.38-48
• /
• 2006

For extending of hot-spot of WLAN, (2) proposes internetworking scheme between wireless LAN (WLAN) and mobile ad-hoc network (MANET), which employ the same layer-2 protocol with different mode. Compared to internetworking schemes between UMTS (Universal Mobile Telecommunications Systems) and WLAN (3-4), the scheme from (2) has relatively low overhead and latencies because WLAN and MANET are physically and logically similar to each other. However, the mode switching algorithm proposed in r2] for internetworking between WLAN and MANET only considers signal strength and determines handoff, and mobile nodes following a zigzag course in pollution area may perform handoff at short intervals. Furthermore, (2) employs mobile IPv6 (MIPv6) at base, which brings still high delay on handoff and overhead due to signal message exchange. In this paper, we present optimized internetworking scheme between WLAN and MANET, modified from (2). To settle ping-pong handoff from (2), we propose adaptive mode switching algorithm. HMIPv6 is employed for IP connectivity and mobility service in WLAN, which solves some shortcomings, such as high handoff overhead and vulnerable security. For routing in MANET, OLSR is employed, which is a proactive Protocol and has optimally reduced signal broadcasting overhead. OLSR operates with current P protocol compatibly with no change or modification. The proposed internetworking scheme based on adaptive mode switching algorithm shows better performance than scheme from (2).