• Annual Conference of KIPS
• /
• 2012.04a
• /
• pp.552-555
• /
• 2012

애드 혹 네트워크는 고정된 인프라 없이 동적으로 구성되는 이동 노드들의 집합으로 독립성을 높일 수 있다. 현재 애드 혹 라우팅 프로토콜과 관련해 단일 경로를 제공하는 라우팅 프로토콜이 제안되어 있으나 노드의 잦은 이동으로 인한 경로 재설정이 발생하는 애드 혹 네트워크의 특성으로 인하여 오버헤드와 지연시간이 증가하게 된다. 이러한 문제를 해결하기 위하여 다양한 라우팅 프로토콜이 제안되었다. 그 중에서도 ADOV(Ad-hoc On-demand Distance Vector)는 On-demand 방식의 프로토콜로서 데이터를 전송하는데 필요할 때만 경로를 설정한다. 그러나 최소비용 기반의 경로 산출이 아닌 링크연결 기반의 경로산출로 인한 불필요한 처리 및 지연이 가중된다. 본 논문에서는 최소 비용 기반의 경로 산출 방안인 SPAODV(Shortest Path AODV)를 제안하고 기존의 AODV 경로산출과 비교분석하여 보다 효율적인 경로산출 방안을 제시한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04a
• /
• pp.298-300
• /
• 2001

VoIP 기술은 사용자 사이에서 call을 설정, 변경, 종료할 수 있는 signaling 프로토콜이 필수적이다. 이러한 점에서 인터넷 프로토콜 네트워크 상에서의 call과 멀티미디어 세션의 실시간 제어를 목적으로 IETF의 MUSIC WG에서 말들어진 새로운 signaling 프로토콜이 SIP(Session Initiation Protocol)이다. 또한, IETF에서 SIP WG이 생겨나면서 이 프로토콜에 대한 연구가 더욱 활발해지고 있다. 본 노문에서는 SIP에 대한 개략적인 내용과 SIP 프로토콜의 기능들을 간략하게 소개하였고, SIP session initiation의 과정과 registration 과정 등의 동작에 대하여 설명하였다. 그리고 User Agent의 기본적인 동작을 설명하고, VOVIDA에서 개발한 SIP의 리눅스용 공개 소스를 통해서 User Agent의 실행되는 과정을 분석하였다.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.9
• /
• pp.2948-2957
• /
• 2000

A broadband access network in B- ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. To establish an end-to-end ATM connection, interworking functions between \'B5.2 interface's connection protocol and the signalling protocol, are perfonned at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. In this paper, we analyze and simulate above two interworking models in tenns of a connection setup delay and completion ratio, when call requests with eBR and VBR transfer capability arrive at the service node. We observed that the completion ratios of the two interworking models are quite closed. However the connection setup delay of parallel interworking model is improved by about 33% compared with that of the sequential interworking model.

• Journal of KIISE:Information Networking
• /
• v.29 no.3
• /
• pp.314-323
• /
• 2002

The routing protocols designed for wired networks can hardly be used for mobile ad-hoc networks due to limited bandwidth of wireless transmission and unpredictable topological change. Recently, several routing protocols for mobile ad-hoc networks have been Proposed. However, when theme protocols are applied to support real time services like multimedia transmission, they still have problems in ad-hoc networks, where the topology changes drastically. In this paper, we propose a new route selection algorithm which selects the most reliable route that is impervious to route failures by topological changes by mobile hoots. For reliable route selection, the concept of virtual zone (stable zone and caution zone) is proposed. The zone is located in a mobile node'transmission range and determined by mobile node's mobility information received by Global Positioning System (GPS). The proposed algorithm is applied to the route discovery procedure of the existing on-demand routing protocol, AODV, and evaluated by simulation in various traffic conditions and mobility patterns.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.7
• /
• pp.62-66
• /
• 2008

In this paper we have proposed a power aware location based routing protocol for wireless ad hoc network. The existing greedy perimeter stateless routing (GPSR) has some problems which are certain node overloaded and void situation. The proposed power aware greedy perimeter stateless routing (PAGPSR) protocol gives a solution for these problems in GPSR. PAGPSR uses power aware and geographically informed neighbor selection to route a packet towards the destination. It also gives a solution for the fundamental problem in geographical routing called communication void. It considers residual energy of battery and distance to the destination for the next hope node selection. When it encounters a void it starts limited-flooding to select next hop node. To evaluate the performance of our protocol we simulated PAGPSR in ns-2. Our simulation results show that our protocol achieves longer network lifetime compared with greedy perimeter stateless routing (GPSR).

• Journal of Korea Spatial Information System Society
• /
• v.12 no.1
• /
• pp.1-9
• /
• 2010

Recently, wireless sensor networks(WSNs) technology has been considered as one of the most critical issues in the ubiquitous computing age. The sensor nodes have limited battery power, so they should consume low energy through their operation for the long-lasting lifetime. Therefore, it is essential to use energy efficient routing protocol. For this, we propose a location-based energy-efficient routing protocol which constructs the energy efficient route by considering the quantity of Energy consumed. In addition, we propose a route reconstruction algorithm to handle the disconnection of message transmission. Finally, we show from performance analysis using TOSSIM that our protocol outperforms the existing location based routing protocols in terms of energy efficiency.

• Annual Conference of KIPS
• /
• 2007.05a
• /
• pp.1068-1071
• /
• 2007

무선 애드 혹 네트워크의 사용이 증가함에 따라 네트워크의 보안 또한 매우 중요하게 인식되어 지는 추세이지만, 현재 무선 애드 혹 네트워크의 보안성 표준안에 대한 정의가 미흡한 상황이다. 현재까지 많은 연구를 통해 제안된 키 관리 프로토콜은 오직 특정 상황에만 적용 가능한 단점을 가지고 있다. 2005년 무선 애드 혹 네트워크에서 안전한 그룹 통신을 위한 새로운 키 합의 프로토콜인 CRTDH 프로토콜이 제안되었다[1]. 이 프로토콜은 효율적으로 그룹 키를 계산할 수 있고, 멤버들의 높은 이동성을 지원한다. 하지만 그룹 키 설정 과정에서 공격자가 송신자와 수신자 사이에서 전달되는 메시지를 위조 할 수 있고, 키의 재설정 과정에서 그룹이 변경 되어도 이전 그룹 키와 동일하게 계산 될 수 있다. 즉 중간자(Man-in-the-middle) 공격과 LCM(Least Common Multiple) 공격에 취약하다. 본 논문에서는 두 가지 공격에 대한 해결책을 제시하여 보안성이 강화된 그룹 키 합의 프로토콜을 제안한다.

• Journal of Korea Society of Industrial Information Systems
• /
• v.10 no.2
• /
• pp.13-20
• /
• 2005

An ad hoc wireless networks forms temporary network without the aid of fixed networks or centralized administration with a collection of wireless mobile hosts. In this case, it is necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination. This paper presents an efficient cluster-based routing protocol scheme for ad hoc networks. The cluster is used for path setup and data delivery. Our cluster-based routing algorithm is designed for the improvement of the load balance. Our simulation results show the improved performance for low mobility networks comparing with the previous works.

• The KIPS Transactions:PartC
• /
• v.13C no.2 s.105
• /
• pp.137-146
• /
• 2006

Because the traditional public key-based cryptosystems are unsuitable for the sensor node with limited computational and communication capability, a secure communication between two neighbor sensor nodes becomes an important challenging research in sensor network security. Therefore several session key establishment protocols have been proposed for that purpose. In this paper, we analyzed and compared the existing session key establishment protocols based on the criterions of generation strategy and uniqueness of the session key, connectivity, overhead of communication and computation, and vulnerability to attacks. Based on the analysis results, we specify the requirements for the secure and efficient protocols for establishing session keys. Then, we propose an advanced protocol to satisfy the specified requirements and verify the superiority of our protocol over the existing protocols through the detailed analysis.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.6
• /
• pp.219-228
• /
• 2007

End-to-end path setup and maintenance are very important for mobile ad-hoc wireless communications, because of the mobility and the limited battery capacity of the nodes in the networks. the AODV routing protocol is the one of mary proposed protocols. However, there are route failure problem with the Proposed protocols between intermediate nodes due to such mobility and exhausted battery characteristics, and this is because only the shortest hop count is considered for the route setup. If route failure happens. Problem such as the waste of bandwidth and the increment of the energy consumption occur because of the discarding data packets in the intermediate nodes and the path re-setup process required by the source node. In addition, it obviously causes the network lifetime to be shortened. This paper proposes a routing protocol based on the AODV routing protocol that it makes use of the remaining energy, signal strength and SNR of the MAC layer resources to setup a path.