• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.952-957
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• 2008

In this paper, explain about collect that Access Point signal and Implementation of Location Tracking System of Wireless Access Point based PDA. Collect Access point signal in PDA then Signal transmits by computer so Computer is analyze collected signal and is seen on picture. we show the Present problem of wireless LAN and position feeler algorithm through this writing paper.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.682-684
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• 2004

최근 유비쿼터스 혁명으로 인해 장소 및 통신기기에 제약 없이 정보를 주고받는 환경으로의 요구가 증대되고 있다. 이러한 요구를 충족하고자 IP 계층에서 투명한 이동성을 제공하는 차세대 무선 프로토콜인 Mobile IPv6 기술이 필수적이다. 그러나 기존 Mobile IPv6는 제한된 컴퓨팅 능력을 가진 소형 이동 단말에는 탑재할 수 없다는 문제점이 있다. 이를 해결하기 위해서는 Mobile IPv6를 하드웨어 모듈로 구현하는 것이 필요하고, 이와 더불어 무선 환경을 지원하기 위해서 무선랜 MAC 기술의 하드웨어 구현이 요구된다. 이에 본 논문에서는 Mobile IPv6 모듈이 무선랜을 지원할 수 있도록 IEEE 802.11 MAC 모듈을 하드웨어로 설계 및 구현하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.19-20
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• 2018

This paper distinguish between the types of LANs used to connect the internet used by many in the fourth industrial era and compare speeds. 802.11 is fastest and it's running at 300Mbps. And second fastest is running at 54Mbps. In compare second, 802.11n is faster second at six times. So we can prediction the wireless lan's transmission speed will be faster in future.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.200-203
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• 2003

By minimizing the burst error of data and correcting the error, we can define the convolution coding and interleaving in IEEE 802.11a wireless tan system. Two step block interleaver was decided by coded bits per OFDM symbol and due to this it comes to the delay time in IEEE 802.11a. This is the point of the question which we must consider. We try to decrease the delay time by all 48-clock from interleavings, and we have proposed a way carried out the interleaving outputs per symbol. So in comparison with the existing interleaver, we can decrease the delay time in reading and writing data, as well as reduce the delay time of bit re-ordering per symbol. Also this scheme is apply in all x-QAM cases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2159-2166
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• 2016

In the IEEE 802.11 DCF (Distributed Coordination Function) protocol, the binary exponential backoff algorithm is used to avoid data collisions. However, as the number of stations increases of, the collision probability tends to grow and the overall network performance is reduced. To solve this problem, this paper proposes a data transmission scheme based on the channel reservation method. In the proposed scheme, channel time is divided into reservation period and contention period. During the reservation period, stations succeeded in channel reservation transmit their own data packets in sequence without contention. During the contention period, each station sends its data packets through contentions as in DCF. During both the reservation period and the contention period, each station sends a request for channel reservation for the next reservation period to an AP (Access Point). After receiving such a channel reservation request from each station, the AP decides whether the reservation is succeeded and sends the result via a beacon frame to each station. Performance of the proposed scheme is analyzed through simulations. The simulation results show that the proposed scheme tends to reduce the collision probability of DCF and to improve the overall network performance.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.564-568
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• 2008

In this paper, MAC(Medium Access Control) algorithm for the IEEE 802.11 DCF(Distributed Coordination Function) improving the performance is proposed and analyzed mathematically. The MAC of IEEE 802.11 WLAN to control data transmission uses two control methods called DCF and PCF(Point Coordination Function). The DCF controls the transmission based on CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance). The DCF shows excellent performance relatively in situation that competition station is less but has a problem that performance is fallen from throughput and delay viewpoint in situation that competition station is increased. This paper proposes an enhanced DCF algorithm that increases the CW to maximal CW after collision and decreases the CW smoothly after successful transmission in order to reduce the collision probability by utilizing the current status information of WLAN. To prove efficiency of proposed algorithm, a lots of simulations are conducted and analyzed.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.145-147
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• 2005

IEEE 802.11 기술이 상용화된 이후 여러 가지 보안에 관련된 취약점들이 드러났다. 이를 보완하기 위하여 802.1li 그룹이 802.11보안 관련 표준안을 제시하였다. 그러나 802.11에서 문제가 되었던 여러 종류의 DoS 공격들 중 몇 개의 공격들은 802.11i에서 아직 유효하다. Deauthe-ntication, Disassociation 메시지를 이용한 공격이 802.1li에서도 유효한 대표적인 공격 중 하나이다. 이 공격은 802.1li에서의 관리 프레임에 802.11과 같은 수준의 데이터 암호화가 적용되기 때문에 가능한 것이다. 본 논문에서는 이러한 취약점을 TKIP를 이용해 제안된 state value를 암호화하여 이를 예상 값과 비교한 후 Deauthentication, Disassociation 공격을 판단하는 메커니즘을 제시 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.712-714
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• 1999

본 논문은 IEEE의 무선 LAN 표준안인 802.11 MAC 프로토콜의 동작을 구현하여 사용자가 구성한 무선 랜 환경의 성능을 측정할 수 있는 망 시뮬레이터의 구현 내용을 기술한다. 구현한 시뮬레이터는 무선 LAN 환경을 구성하는 기능, 성능 평가에 영향을 미치는 인자의 변경 및 성능평가를 위한 그래픽 차트의 출력 기능을 제공한다. 또한 MAC 프로토콜 모듈과 시뮬레이터의 의존성을 최소화하여 새로운 MAC 프로토콜을 쉽게 이식할 수 있도록 설계하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.64-72
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• 2012

Synchronization including timing recovery, frequency offset compensation, and frame synchronization is most important signal processing block in all wireless/wired communication systems. In most communication systems, synchronization schemes based on training sequences or preambles are used. WLAN standards of 802.11a/g/n released by IEEE are based on OFDM systems. OFDM systems are known to be much more sensitive to frequency and timing synchronization errors than single carrier systems. A loss of orthogonality between the multiplexed subcarriers can result in severe performance degradations. The starting position of the frame and the beginning of the symbol and training symbol can be estimated using correlation methods. Correlation processing functionality is usually complex because of large number of multipliers in implementation especially when the reference signal is non-binary. In this paper, a simple correlation based synchronization scheme is proposed for IEEE 802.11a/g/n systems. Existing property of a periodicity in the training symbols are exploited. Simulation and implementation results show that the proposed method has much smaller complexity without any performance degradation than the existing schemes.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.254-258
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• 2006

IEEE 802.11 이 표준화 되면서 성능 분석에 대한 연구가 많이 활발히 진행되고 있다. 가장 대표적인 802.11 DCF 분석모델로 비앙키 모델이 있는데, 이는 채널에 에러가 없는 상황을 가정하여 분석하고 있다. 비앙키 모델에서는 모든 노드는 전송 시도를 했을 때 시간에 독립적인 확률p 의 전송 실패율을 갖게 된다는 디커플링 가정을 기반으로 분석하였으며, 대부분의 확장논문들 역시 이 가정을 바탕으로 하고 있다. 본 논문에서는 디커플링 가정을 사용하지 않는 방법으로 채널에러가 존재하는 IEEE 802.11 DCF의 성능을 분석하였으며 분석 결과를 NS2 를 이용한 시뮬레이션과의 비교를 통해 분석의 정확성을 검증하였다.