• 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.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.109-114
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• 2004

Increasing popularity of WLAN and advancement of WPAN allow user to connect to the Internet easily today. The increasing of number of networking mobile device such as laptop and PDA requires computing devices to share high speed Internet line or work on networks in most cases. This has stimulated the demand of access point that supports multiple network interfaces. This paper describes the process of design, implementation and test of the wired/wireless integrated access point that supports multiple network interfaces such as wired LAN, wireless LAN, Bluetooth, and Broadband network. We designed and developed the hardware system and protocol software to integrate heterogeneous network. The system has shown compatibility with standard specification and good performance through testing with various network devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.1012-1017
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• 2008

Recently, the use of wireless fan is increased by the development of wireless communication and convenience. Moreover, it makes an issue of security threat and vulnerability of wireless tan. Therefore, the IEEE established new standard such as 802.11i in 802.11 to supplement security vulnerability of wireless tan. But the security threat that does not solve, still remains. In this paper, we proposed that the location detection algorithm, that is used Kalman-Filter, Lateration and RSSI, and the mechanism that detects security status of AP and unauthorized AP by using beacon-frame of AP in building. Finally, we confirmed performance of proposed algorithm is good in comparison of established algorithm.

• Journal of Digital Contents Society
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• v.12 no.3
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• pp.347-353
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• 2011

In HIPERLAN/2, the radio channels are assigned by AP(Access Point) that is centrally operated and the MAC protocol is based on TDMA/TDD. Mobile terminal that data transmission is necessary to uplink requests radio resource to AP through RCH channel. The changing number of RCHs in each MAC frame is important because too many RCHs may result in a waste of radio resources and too few RCHs may result in many access collisions and prolong time that connect to AP. Hence the number of RCH should be allocated properly according to traffic. From these point, this paper proposes an scheme that dynamically assigned the number of RCH which is based on the number of success and collision of message in previous MAC frame. To prove efficiency of proposed scheme, lots of simulations are conducted and analyzed.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.3 no.1
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• pp.5-14
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• 2004

"언제, 어디에서, 어떤 형태의 접속"도 가능하게 하는 유비쿼터스 네트워크 환경의 실현을 위해 음성, 데이터의 통합은 우선 지원되어야 할 애플리케이션이다. 블루투스는 음성, 데이터의 동시 처리가 가능한 무선 개인 영역 네트워크(WPAN: Wireless Personal Area Network) 표준이다. 저가, 저전력의 무선 통신을 기반으로 휴대폰, 무전 전화기(Cordless Telephone) 의 음성 통화와 노트북, PDA 등의 정보기기의 인터넷 접속을 가능하게 한다. 본 논문에서는 블루투스의 음성, 데이터 통합처리를 구현한 블루투스 액세스 포인트(Access Point)에 대해 기술한다. 근거리 무선 데이터 통신과 유실 네트워크의 연결을 이루어 노트북, PDA 등 단말기의 인터넷 동시 접속을 지원하며 블루투스 폰의 VoIP 통화를 구현하였다. 개발 완료된 시스템의 테스트 결과 다양한 벤더들의 제품들과 호환성을 이루어 표준안을 만족하였으며 성능 면에서 역시 규격에서 제시한 최대치에 근접한 매우 우수함을 나타내었다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.286-288
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• 2004

무선 통신의 발달로 언제 어디서나 누구와도 통신이 자유롭게 되었다 하지만, 무선 통신을 사용하게 됨으로써 통신 사용자와 액세스 포인트, 액세스 포인트와 서버(Server)가 통신을 할 경우 유선 네트워크와는 다른 인증 방식이 요구되었다. 무선 네트워크에서 사용자 인증을 위해 801.x EAP, SSID, CHAP 및 WEP를 이용한 다양한 인증 방식이 사용되고 있다. 본 논문에서는 사용자를 안전하게 인증할 수 있는 효율적인 인증 방법을 제안한다. 절기서는 기존의 PPP CHAP을 수정하여 인증 서버와 사용자간의 상호 인증을 할 수 있도록 했다. 또한 강한 일-방향 해시 함수(Strength One-Way Hash Function)을 사용하여 생성된 결과 값을 일회용 패스워드(One Time Password:OTP)로 사용하여 재공격(Reply Attack)을 방지했다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.348-357
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• 2012

Recently, smartphone, notebook, PC and other supporting wireless LAN device have come into wide use. By increasing user that use wireless LAN device, wireless traffic also increased. If wireless traffic through one AP is increase, it causes throughput decrease. To solve this problem, wireless LAN service provider install more AP where overload occurred. But this is not enough. Because stations can't know AP's load factor, and APs do nothing for load balancing. In this paper, we propose Multi-Interface Access Point(MIAP) to solve this problem. MIAP operate same as multiple APs with multi-interface, and MIAP measure each interface's load periodically. If MIAP detect overloaded interface, MIAP transfer station from overloaded interface to under-loaded interface. We conducted an experiment for verifying existing problem, and we found this problem occurred. We plan an experiment scenario for a comparison between existing AP and MIAP, and excute these experiment. In the result, we show MIAP with load balancing can improve total throughput about 72% and stabilize delay jitter than existing AP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3440-3446
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• 2015

One of technologies that make it possible for users to enjoy always-on Internet service using potable devices does be Wifi. However, users frequently feel its connection is not stable or its speed becomes slow. On the other hand, users see multiple available Wifi access points exist often. In this paper, we present a smartphone application, called to WiSMax, that periodically changes its Wifi connection to the best one among available Wifi access points to maximize its speed. Experimental results show that WiSMax presents faster Internet connection than IEEE802.11 as much as about fifteen percent and higher signal strength than IEEE802.11 as much as about five dBm.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.499-503
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• 2002

초고속 무선인터넷 환경을 구축하기 위한 인프라의 강력한 대안이 되고 있는 무선랜 시스템은 사무실 단위의 소규모 네트워크 환경에서 벗이나 공중망 환경으로 진화하고 있다. 무선랜 시스템의 공중망 적용을 위한 주요 기술 중 하나는 무선랜 시스템의 보안성을 보장하는 것이다. 본 논문에서는 무선랜 사용자와 액세스포인트 사이에서 이루어지는 새로운 암호 키 교환 프레임을 제시하고, 그 결과로써 효율적인 무선구간 암호 키 갱신 및 보안성이 향상된 무선구간 데이터 프레임 암호화 효과를 보인다.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.184-188
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• 2002

본 논문에서는 자체 제작된 블루투스 액세스포인트 (ETRI-AP)와 블루투스 단말장치 사이에 ACL 연결을 맺고, 이 연결을 통해 데이터 전송 속도를 측정함으로써 다수의 슬레이브와 통신해야 하는 경우 길이가 짧은 패킷을 사용하는 것이 효율이 좋음을 보였다.