Aruba의 802.11ac White Paper 정리

출처: http://www.arubanetworks.com/pdf/technology/whitepapers/WP_80211acInDepth.pdf

Aruba사의 "802.11ac in-depth" white paper를 정리한 자료입니다.

   

802.11ac Technology Fundamentals

• 802.11ac Wave 1
  • 80MHz
  • 256QAM
  • TX Beamforming
• 802.11ac Support
  • Max Multi STA throughput (MAC data service access point) > 1 Gbps, Max Single STA TP > 500Mbps
  • 5GHz Band O. 2.4GHz X
• Content and features
  • Wider RF channel bandwidth
    • 802.11n: 40MHz -> 802.11ac 80~160MHz
  • More spatial streams
    • 802.11n: 4 -> 802.11ac: 8
  • Multi-user MIMO: DL MU-MIMO only
  • Modulation and Coding
    • 256QAM 3/4, 5/6 coding
    • 802.11ac does not offer every rate option for every MIMO combination
  • Other elements/features
    • Single sounding and feedback
    • MAC Modifications
    • Coexistence mechanisms for 20/40/80/160MHz channels
  • Non-HT duplicate Mode
• Bandwidth and throughput figures
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• PHY LAYER ENHANCEMENT
  • PHY enhancements beamforming and more
    • Summary of PHY Enhancements
      • 
    • Channel Width
      • U-NII 1: 5150 ~ 5250 (Indoor Only)
      • U-NII 2: 5250 ~ 5350 (DFS, TPC)
      • U-NII 2 Extended(World-wide): 5450-5725 (DFS, TPC)
        • 5600~5650은 미국에서 weather radar에서 사용하므로 사용 못함
      • U-NII 3/ISM: 5735 ~ 5825(Indoor, Outdoor bridge)

           

System	Bandwidth	Subcarrier	Times
a/g	20MHz	48	1
n/ac	20 MHz	52	1
n/ac	40MHz	108/52	2.07
ac	80MHz	234/52	4.5

   

• Review of MIMO techniques

     

• MAC Layer Enhancement
  • MU-MIMO, modulation and MAC enhancements
    • MU-MIMO
      • Precoding algorithms for beamforming and DL MU-MIMO
      • Scheduling DL MU-MIMO multiple-transmit opportunities
        • No more than four client can be targeted simultaneously
        • No client can use more than 4 streams
        • All streams in a DL MU-MIMO TX must use the same MCSs

           

    • Modulation and Rate

     

  

  • MAC Changes
    • Frame aggregation, A-MPDU, A-MSDU
    • Encryption and the GCMP Option
    • Power-save enhancements
    • Extended basic service set load element
    • Co-existence and backwards compatibility
      • Multipart RF header that uses 802.11a/n modulation
      • 802.11n greenfield modes for non-backward compatible -> never implemented
    • Protection, dynamic bandwidth and channelization
    • 802.11ad and fast session transfer
• History and timeline
• Regulatory limitations

   

802.11N Experience

• Lesson Learned
  • MIMO Works: Even LOS, there are many multipath
  • 40MHz Ch. Are very useful in 5GHz
  • MAC frame aggregation, A-MP여

       

802.11AC Deployment