• Title/Summary/Keyword: mixed-mode wireless LAN

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A Study on Dynamic Key Management in Mixed-Mode Wireless LAN (혼합모드 무선랜에서의 동적 키 관리 방식 연구)

  • 강유성;오경희;정병호;정교일;양대헌
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.4C
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    • pp.581-593
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    • 2004
  • The interest in wireless LAN security is on the increase owing to a role of high-speed wireless Internet infrastructure of wireless LAN. Wi-Fi has released WPA standard in order to overcome drawbacks of WEP algorithm that is security element of current IEEE 802.11-based wireless LAN system. Pairwise key management and group key management in a mixed-mode which supports both terminals running WPA and terminals running original WEP security are very complicate. In this paper, we analyze flaws in WPA authenticator key management state machine for key distribution and propose the countermeasures to overcome the analyzed problems. Additionally, WPA authenticator key management state machine to which the solutions are applied is described. The reconstructed WPA authenticator key management state machine helps the AP perform efficiently group key exchange and group key update in the mixed-mode.

A Low-Voltage High-Performance CMOS Feedforward AGC Circuit for Wideband Wireless Receivers

  • Alegre, Juan Pablo;Calvo, Belen;Celma, Santiago
    • ETRI Journal
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    • v.30 no.5
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    • pp.729-734
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    • 2008
  • Wireless communication systems, such as WLAN or Bluetooth receivers, employ preamble data to estimate the channel characteristics, introducing stringent settling-time constraints. This makes the use of traditional closed-loop feedback automatic gain control (AGC) circuits impractical for these applications. In this paper, a compact feedforward AGC circuit is proposed to obtain a fast-settling response. The AGC has been implemented in a 0.35 ${\mu}m$ standard CMOS technology. Supplied at 1.8 V, it operates with a power consumption of 1.6 mW at frequencies as high as 100 MHz, while its gain ranges from 0 dB to 21 dB in 3 dB steps through a digital word. The settling time of the circuit is below 0.25 ${\mu}s$.

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