• 한국통신학회논문지
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• 제34권5B호
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• pp.455-462
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• 2009

본 논문에서는 다중 홉으로 구성된 IEEE 802.11 기반의 메쉬 네트워크에서 노드 간에 패킷 전송 시 버퍼 오버플로우에 의한 패킷 손실을 줄이고 수신되는 패킷의 공평성을 높이기 위한 버퍼 관리 방식을 제안한다. 제안된 방식은 전송 패킷을 전달하는 중간 노드에서 인접 메쉬 라우터와 이동 노드로부터 전송된 패킷을 균등하게 수신하고, 각 메쉬 라우터에서 다중 홉을 거친 패킷 수신율을 향상시킴으로써 패킷 전송지연과 노드의 에너지 소모를 줄일 수 있다. 제안된 방식은 기존의 IEEE 802.11 MAC 프로토콜 하에서 수정된 RTS/CTS를 이용하여 전송될 패킷의 크기를 미리 인지함으로써 패킷 손실과 패킷 공평성을 향상시킨다. 시뮬레이션을 이용하여 기존의 방식과 제안된 방식의 패킷 손실률, 각 메쉬 라우터에서 수신되는 패킷 양을 측정함으로써 제안된 방식의 성능을 비교 평가하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제14권3호
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• pp.261-265
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• 2008

ITSP(Internet Telephony Service Provider)를 이용한 VoIP 서비스의 사용자가 증가함에 따라 VoIP 스팸은 큰 문제로 대두되고 있다. 기존의 일반 전화 때부터 사용되던 스팸은 실시간적 음성 통신이라는 특성상 콘텐츠 필터링을 하기 어렵기 때문에 콜 행위 패턴 조사를 통해 스패머(Spammer)를 구분하고 있다. 그러나 잘못된 오판으로 인한 문제와 스팸으로 인식하는 임계값을 넘지 않는 한도의 스팸 전송, 그리고 여러 사용자가 하나의 번호를 공유하여 사용하는 경우에는 여전히 스팸의 위협이 남아 있다. 이에 본 논문에서는 튜링 테스트를 이용한 VoIP 스팸 방지를 제안한다. 제안된 방법은 송신자에게 튜링 테스트를 거치게 하고, 튜링 테스트를 통과한 사용자만 수신자와 연결이 되는 방식으로 동작한다. 또한 튜링 테스트를 통과한 정상적인 사용자에게는 티켓을 줌으로써 재발신시 거쳐야하는 튜링 테스트의 번거로움을 줄일 수 있다. 제안된 방법은 ASUS WL-500G 무선 공유기 및 Asterisk IP-PBX에서 구현되었고 실험을 통해 제안된 방법의 유효성을 검증하였다.

• 대한전자공학회논문지SD
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• 제46권11호
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• pp.56-65
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• 2009

최근 SoC의 집적도가 증가함에 따라 칩 내부의 통신 효율성은 시스템 성능에 직접적인 영향을 미치고 있다. 이에 따라 칩내부의 통신 메커니즘은 과거 shared wire를 이용한 버스 시스템에서 라우터를 기반으로 하는 NoC로 진화하고 있다. 하지만, NoC 내부의 라우터는 컨트롤 로직이 복잡해짐에 따라 신호 전달 과정에서 지연시간을 증가시켜 NoC의 성능을 제한시킨다. 따라서 본 논문에서는 이러한 지연시간을 개선시키기 위하여 낮은 복잡도를 갖는 라우터를 제시한다. 제안한 라우터의 구조 검증 및 성능 평가를 위하여 ESL 기법의 시뮬레이션 플랫폼을 구축하였다. 본 논문에서 제안한 NoC 구조는 기존의 VC 라우터 기반의 NoC에 비해 대역폭은 약 1-2% 정도 감소하였지만, 평균적으로 약 50%의 지연시간이 감소 효과를 보였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2004년도 춘계학술발표대회
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• pp.1417-1420
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• 2004

The combination of Fast-Handoff and Hierarchical Mobile IPv6 (F-HMIPv6) allows the anticipation of the layer3 handoff such that data traffic can be efficiently redirected to the mobile node's new location before it moves there. However, after moving to the new Access Router (NAR), if the mobile node (MN) sends the Local Binding Update (LBU) to the Mobility Anchor Point (MAP) before receiving all of the buffered packet from the NAR, the MN may receive the general packet from the MAP. That is, the MN may simultaneously receive two types of packet which has different sequence number. These cause the confusion in packet order, and the MN sends the dup ack for the packet retransmission to the CN. It results in the degradation of the TCP performance. Therefore, we propose the scheme for minimizing the out-of-sequence packet in F-HMIPv6.

• Journal of Information Technology Applications and Management
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• 제10권2호
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• pp.61-71
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• 2003

Ad-hoc networks are characterized by multi-hop wireless links, frequently changing network topology and the need for efficient dynamic routing protocols. In an Ad-hoc network, each host assumes the role of a router and relays packets toward final destinations Because a packet is broadcast to all neighboring nodes, the optimality criteria of wireless network routing is different from that of wired network routing. tn this paper 1 point out the more important cost factor than the number of links in the Ad-hoc network. A class routing protocols called on-demand protocols has recently found attention because of their low routing overhead since it performs a blind flooding to look for a path. In this paper, 1 propose the method which reduces overhead by using the information of neighboring nodes and doing a selective flooding. Simulation results demonstrate better reduction of routing overheads with this scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2013-2014
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• 2006

For large capacity optical CDMA networks, we propose a shared-type encoder/decoder based on an tunable wavelength conveter (TWC) and an arrayed waveguide grating (AWG) router. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using three types of wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC), the generalized multi-wavelength Reed-Solomon code(GMWRSC) and the matrix code. Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.529-532
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• 2000

This paper addresses how to be connected with end-to-end shortcut using ATM Switched Virtual Connection (SVC) in ATM-based Multi-Protocol Label Switching (MPLS) Networks. Without additionally existing ATM Ships-in-the-Night (SIN) mode, when the stream is continuously transmitted at the same destination with the lapse of determined aging time, the connection is changed with end-to-end shortcut connection using ATM signaling. An ATM direct short circuit is performed an IP and ATM effective integration. An ATM shortcut has a number of advantages, like higher throughput, shorter end-to-end delay, reduced router load, better utilization of L2 Quality of Service (QoS) capabilities, and route optimization. In particular between other MPLS domains, this can be efficiently improved the performance of networks.

• ETRI Journal
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• 제35권1호
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• pp.41-50
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• 2013

Network Mobility (NEMO) handles mobility of multiple nodes in an aggregate manner as a mobile network. The standard NEMO suffers from a number of limitations, such as inefficient routing and increased handoff latency. Most previous studies attempting to solve such problems have imposed an extra signaling load and/or modified the functionalities of the main entities. In this paper, we propose a more secure and lightweight route optimization (RO) mechanism based on exploiting the firewall in performing the RO services on behalf of the correspondent nodes (CNs). The proposed mechanism provides secure communications by making an authorized decision about the mobile router (MR) home of address, MR care of address, and the complete mobile network prefixes underneath the MR. In addition, it reduces the total signaling required for NEMO handoffs, especially when the number of mobile network nodes and/or CNs is increased. Moreover, our proposed mechanism can be easily deployed without modifying the mobility protocol stack of CNs. A thorough analytical model and network simulator (Ns-2) are used for evaluating the performance of the proposed mechanism compared with NEMO basic support protocol and state-of-the-art RO schemes. Numerical and simulation results demonstrate that our proposed mechanism outperforms other RO schemes in terms of handoff latency and total signaling load on wired and wireless links.

• Journal of Communications and Networks
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• 제7권3호
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• pp.377-384
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• 2005

The purpose of this research is to develop and evaluate a traffic engineering architecture that uses local state information. This architecture is applied to an Internet protocol radio access network (RAN) that uses multi-protocol label switching (MPLS) and differentiated services to support mobile hosts. We assume mobility support is provided by a protocol such as the hierarchical mobile Internet protocol. The traffic engineering architecture is router based-meaning that routers on the edges of the network make the decisions onto which paths to place admitted traffic. We propose an algorithm that supports the architecture and uses local network state in order to function. The goal of the architecture is to provide an inexpensive and fast method to reduce network congestion while increasing the quality of service (QoS) level when compared to traditional routing and traffic engineering techniques. We use a number of different mobility scenarios and a mix of different types of traffic to evaluate our architecture and algorithm. We use the network simulator ns-2 as the core of our simulation environment. Around this core we built a system of pre-simulation, during simulation, and post-processing software that enabled us to simulate our traffic engineering architecture with only very minimal changes to the core ns-2 software. Our simulation environment supports a number of different mobility scenarios and a mix of different types of traffic to evaluate our architecture and algorithm.

• 한국게임학회 논문지
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• 제2권1호
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• pp.23-29
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• 2002

Multicast protocols are efficient methods of group communication such as video conference, Internet broadcasting and On-Line Game, but they do not support the various transmission protocol services like a reliability guarantee, FTP, or Telnet that TCPs do. The Purpose or this Paper is to find a method to utilize multicast routers can simultaneously transport multicast packets and TCP packets. For multicast network scalability and error recovery the existing SRM(Scalable Reliable Multicast)method has been used. Three packets per TCP transmission control window site are used for transport and an ACK is used for flow control. A CBR(Constant Bit Rate) and a SRM is used for UDP traffic control. Divided on whether a UDP multicast packet and TCP unicast packet is used simultaneously or only a UDP multicast packet transport is used, the multicast receiver with the longest delay is measured on the number of packets and its data receiving rate. It can be seen that the UDP packet and the TCP's IP packet can be simultaneously used in a server router.