• Electronics and Telecommunications Trends
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• v.21 no.6 s.102
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• pp.202-211
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• 2006

본 논문에서는 2.4GHz 마그네트론을 이용하는 RF 전구에 대하여 동 대역을 사용하는IEEE 802.11b 기반의 무선랜과 전파간섭을 분석하였다. RF 전구가 무선랜에 미치는 전파간섭을 분석한 결과, LOS 환경(무선랜 수신전력 -63dBm/MHz)에서는 무선랜 채널 9, 10에 약 1~2Mbps의 전송속도 저하를 유발하였으며, Non-LOS 환경(무선랜 수신전력 -78dBm/MHz)에서는 무선랜 채널 6-11번에 통화절단 현상을 야기하였다. 그러나, RF 전구 수에 따른 간섭전력의 누적효과는 없는 것으로 나타났다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10A
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• pp.816-822
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• 2011

This paper provides the performance measurement and analysis of Wireless LAN IEEE 802.11 in a mobile environment. The performance of IEEE802.11b/g and IEEE802.11p that is designed for Vehicle-to-Vehicle(V2V) communication is measured and analyzed. Diameter of communication, link access time and delay are measured as vehicle's speed varies. Also, the performance is checked in a situation that the load to network varies. In conclusion, the futher research topics are discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.437-444
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• 2014

The unmanned ship control system controls the unmanned ship at a distance in ocean. Expecially, in order to control the unmanned ship, it needs the wireless communication networks and we use the IEEE 802.11 based WLAN. The IEEE 802.11 based WLAN technology for supporting a wide bandwidth is suitable for unmanned ship control system which has to transmit the multimedia data. First, we design the system structure for controlling the unmanned ship. Then, in order to overcome the limited communication area, we design the network structure for the unmanned ship communication network which can use a various communication network. we implemented and evaluated the unmanned ship system based on WLAN. We controlled the unmanned ship by use the WLAN and confirmed the signal feature of WLAN in the ocean.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1075-1082
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• 2004

Wireless LAN is a rather mature communication technology connecting mobile terminals. IEEE 802.11 is a representative protocol among Wireless LAN technologies. The basic medium access control (MAC) mechanism of IEEE 802.11 is called distnbuted coordination function (DCF). DCF shows poor throughput and high drop rate as the number of stations and offered traffic load increase. In this paper we propose an effective mechanism using dynamic mimmum contention window(CWmin) in wireless LAN~ and show that performance improves via simulations. Proposed dynamic CWmin scheme exhibits superior performance as the number of stations and offered load grow. As, our proposed scheme is expected to be more effective in highly densed wireless LAN environment.

• Journal of KIISE:Information Networking
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• v.37 no.2
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• pp.85-93
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• 2010

WLAN virtualization can make multiple simultaneous experiments, each of which is conducted by a separate researcher, share scarce wireless resources in an IEEE 802.11 WLAN. The experiment performed in a virtualized WLAN should be consistent with that in a non-virtualized WLAN. The more similar these two experimental results, the better the consistency. To this end, we propose a novel virtualization scheme that has good consistency by preventing multiple simultaneous experiments from interacting with one another, without any modifications to the IEEE 802.11 standard. Through an intensive simulation study, we confirm that the consistency depends not only on the number of simultaneous experiments but also on wireless channel characteristics such as Doppler frequency and Ricean factor. According to such dependencies, the proposed scheme is optimized, so that it supports good consistency.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.217-222
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• 2005

The IEEE 802.11 based wireless local area networks are candidates to lead the broadband connectivity in the home and office scenarios. Recently IEEE proposed the 802.11e as a new standard to provide appropriate Quality of Services to a plethora of emerging real-time multimedia and high demanding applications such as high definition movie and audio distribution, video-conference and voice over IP. This paper studies the IEEE 802.11e/IEEE 802.11b interactions focusing on potential unfairness problems that might appear in networks with heterogeneous wireless LAN technologies as well as in the IEEE 802.11e deployment phase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.338-348
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• 2005

Currently, IEEE 802.11 Wireless LAN (WLAN) is rising as the most popular means for the broadband wireless access network. In this thesis, we propose a QoS(Quality of Service)-Oriented mechanism using handshaking method of scanning phase in IEEE 802.11 handoff. In conventional process for handoff, the major criterion to select the best AP(Access Point) among candidates is normally based on the RSS(Received Signal Strength), which does not always make the selected network guarantee the maximum achievable performance. Even though the link quality with a neighboring AP is excellent, the AP may not be a good candidate to handoff to simply because MAC(Medium Access Control) protocol of IEEE 802.11 standard is contention-based such as CSMA/CA. Therefore, if we apply network level information to AP selection criteria, we can achieve better handoff efficiency rather than before. The analysis and simulation results applied to our new mechanism show clearly better performance than AP selection based on traditional handoff method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.191-200
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• 2007

As the IEEE 802.11 WLAN has widely installed as a high-speed wireless network information infrastructure, there has been growing interest in both security and mobility of mobile terminals. However, for the case of mobile terminal employing IEEE 802.11i security standard, it is known that the user authentication procedure of IEEE 802.1x for stronger security enforcement may, due to its large delay, not be suitable for real-time multimedia communication. In this paper, we have proposed fast authentication method to resolve the above authentication delay problem, and verifies its performance via simulation analysis. Mobile terminals can get AP information reliably, and selectively execute authentication in advance during handover, which results in fast user authentication. In addition, by effectively managing the authentication information in mobile terminal, which are distributed in advance for pre-authentication, the problem of long-time revelation of authentication information has been solved.

• TTA Journal
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• s.99
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• pp.123-130
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• 2005

초고속 무선인터넷에 대한 요구가 급성장하면서 기존의 무선랜(WLAN: Wireless Local Area Network) 시스템이 초고속 무선인터넷의 기반구조로써 자리잡고 있음은 주지의 사실이다. 그러나 합리적인 가격과 편리성에도 불구하고 보안의 취약성이 문제로 남아있었다. 이 문제의 해결을 위한 노력의 결실로써 IEE 802.11i 표준은 지난 2004년 6월 24일에 IEEE802 SEC(Sponsor Executive Committee)의 투표를 통과하여 2004년 7월에 IEEE 표준으로 확정되었다[2]. 또한 신속한 국제표준화를 위해서 ISO/IEC JTC1 Fast Track DIS(Draft International Standard)로 상정되어 2004년 12월 8일부터 최종 승인을 위한 투표를 진행 중이다[5]. 본 고에서는 IEEE 802.11i 무선랜 보안 표준이 담고 있는 인증 방식, 키 교환 방식 및 암호 알고리즘에 대하여 분석해 보고자 한다.

• Information and Communications Magazine
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• v.24 no.6
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• pp.67-75
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• 2007

최근 다양한 멀티미디어 응용 및 시나리오가 등장함에 따라 멀티캐스트 전송 기법의 중요성이 더욱 부각되고 있다. 본고에서는 무선랜의 MAC 계층 멀티캐스트 기법에 초점을 맞추어 현재 IEEE 802.11 표준에서 정의하는 멀티캐스트 기법은 어떻게 동작하며 그 한계점은 무엇인지 살펴본다. 그리고 본고에서 명시된 문제점을 해결하기 위하여 활용 가능한 IEEE 802.11 무선랜 MAC 계층의 다양한 멀티캐스트 기법 중 대표적인 관련 연구들과 그 문제점을 함께 알아본다. 마지막으로 효율적인 IEEE 802.11 MAC 계층 멀티캐스트 기법을 설계할 때 고려해야 할 요구 사항을 정리한다.