• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.196-198
• /
• 2003

배터리를 주 전력원으로 사용하는 MANET(Mobile Ad hoc NETwork)에서 전력 소비를 줄이는 방법에 대한 연구가 활발히 진행되고 있지만, 이의 실험을 지원하는 시뮬레이션 도구를 찾아보기는 어렵다. 본 논문에서는 IEEE 802.11의 DCF-PSM 시뮬레이션 환경을 제공하기 위해 ns-2에 PSM 모듈을 구현하였고, 특히 전력 소비와 관련된 결과 자료를 쉴게 생성하기 위해 여러 가지 편의성을 제공하는 에너지 모델을 제안하였다. 이러한 모들의 개발로 PSM 환경에서의 상위 계층 프로토콜의 성능 평가나 PSM에 적합한 새로운 상위 계층 프로토콜의 개발이 가능해졌고, PSM을 개선하는 알고리즘의 구현과 그의 성능 평가도 훨씬 쉽게 이루어질 수 있게 되었다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.337-339
• /
• 2003

NGN 시대가 될수록 이동성을 지원하면서 네트워크를 효율적으로 이용하는 기술이 요구된다. Mobile Ipv6은 이와 같은 요구조건을 만족시키는 좋을 방법이다. 본 논문에서는 이동호스트가 핸드오버를 수행할 때 발생하는 Triangle Routing 오버헤드를 감소시키는 핸드오버 프로토콜을 제안한다. 제안된 핸드 오버 프로토콜은 Previous Access Router(PAR)가 Binding Update(BU) 메시지를 전송하게 함으로써 PAR에서 New Access Router(NAR)로 포워딩되는 패킷의 개수를 감소시킨다. 제안된 핸드오버는 NS-2(network simulation)에서 시뮬레이션 되었고, 멀티미디어 데이터 통신에 사용되는 UDP를 이용하였다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.1
• /
• pp.71-76
• /
• 2013

In this paper, end-to-end performances for some VoIP traffics are measured and analyzed over MANET(Mobile Ad-hoc Networks) with packet aggregation transmission under blackhole attacks. A VoIP simulator based on NS-2 is used for performance measure. In the simulation, MOS, call connection ratio, network delay and packet loss rate are measured for end-to-end transmission performance. With analysis of measured data, characteristics of each traffics for performance parameters of packet aggregation transmission is showed on MANET under blackhole attack, As a results of this paper, some considerations be required for packet aggregation transmission are suggested to implement VoIP services on MANET under blackhole attacks.

• The Journal of the Korea Contents Association
• /
• v.10 no.10
• /
• pp.19-25
• /
• 2010

While Snoop improves network performance by using local retransmission in case of packet loss in wireless network, it has security vulnerability to be unable to countermeasure against falsified ACKs attacks. Therefore in this paper, we suggest a modified Snoop with an extra buffer in addition to original Snoop buffer. Even though packets are exhausted in original buffer by falsified ACKs attacks, proposed Snoop can locally retransmit the packets saved in the extra buffer. The simulation by NS-2 shows that proposed Snoop countermeasure efficiently against falsified ACKs attack and builds securer Snoop protocol.

• Journal of KIISE:Information Networking
• /
• v.37 no.3
• /
• pp.234-242
• /
• 2010

The demand on various broadcasting services has been greatly increasing in the area of mobile communication. In IEEE802.16e standard and mobile WiMAX, the multicast broadcast service (MBS) uses shared downlink channel for efficiently supporting a number of users. In this paper we propose a dynamic modulation and coding scheme with relay network to enhance the performance of MBS. The proposed approach employs the adaptive modulation and coding scheme for both the base station and relay station to achieve consistently high throughput. The result of computer simulation with NS-2 shows that the throughput and transmission time are significantly improved by using the proposed approach compared to the existing schemes having a fixed modulation level for the RSs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.05a
• /
• pp.289-293
• /
• 2011

In our previous research, we proposed a MOST GATEWAY system for organically connected to the network MOST150 and MOST 25 and we proposed a simulation design method for performance analysis of Scheduling Algorithm in MOST GATEWAY system. Therefore in this paper, after comparing the performance among the existing scheduling algorithm methods in MOST25 and MOST150 Networks, we use NS-2 simulator in order to analyze the performance. Finally, we present an improvement scheme of the efficiency and scalability.

• Korean Journal of Optics and Photonics
• /
• v.8 no.5
• /
• pp.410-414
• /
• 1997

Laser projection display is a full color display system for large area. In this system, laser beams are modulated at acousto optic modulators(AOM) according to the video signal. AOM consists of a $TeO_2$ crystal and a $LiNbO_3$ transducer. We calculated the acoustic wave propagating from transducer to acousto optic media and made AOM by the calculated results. We compared calculated results with fabricated AOM by measuring modulation efficiency at various frequency. The modulation efficiency of AOM is 85% at the carrier frequency of 144MHz and the rise time is 41.5 ns.

• The Journal of the Korea Contents Association
• /
• v.10 no.5
• /
• pp.45-51
• /
• 2010

Appearance of a cloned AP(Access Point) causes MS(Mobile Station) to break an association with a normal AP(Access Point). If signal power of the cloned AP is stronger than that of the normal AP, MS associates with the cloned AP. Therefore, MS is easily exposed to attackers who installed the cloned AP. In this paper, we distinguish cloned AP from normal AP by using the association time and frame sequence number between normal AP and MS, then isolates the cloned AP. The simulation by NS-2 shows that our mechanism isolates efficiently a cloned AP and builds safer wireless LAN environment.

• The KIPS Transactions:PartC
• /
• v.12C no.6 s.102
• /
• pp.927-932
• /
• 2005

We investigate the effects on performance of using a partial retransmission mechanism in Optical Burst Switched(OBS) networks. In our scheme, the lost segments of a burst are retransmitted in the OBS layer. We also propose an optical resource reservation using the partial retransmission mechanism. Our scheme attempts to improve the burst contention resolution and optical channel utilization. The performance of the proposed mechanism is analyzed by NS2 simulations. Simulation results indicate that link utilization of the OBS network is improved makedly at the expense of signaling and ingress buffers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.9A
• /
• pp.878-883
• /
• 2006

New emerging wireless broadband internet can make many broadband multimedia services. The networked intelligent mobile robot service is one of the new services. In the networked robot control, both the on-line real-time control and the reliability of control data transmission are very important. Considering the real-time control and data reliability, an efficient transmission method based on UDP protocol is proposed. The proposed method allocates the priority to the robot control data and the transmission of the robot data at the base station is carried out in duplicate manner. NS-2 simulation results show that the proposed scheme has a very low packet delay and low packet errors.