Air tight 11ac webinar series   session 2 - 11ac feature deep dive - june 2014
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Air tight 11ac webinar series session 2 - 11ac feature deep dive - june 2014

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11ac Deeper Dive

11ac Deeper Dive
- 11ac Feature Review
- Channel Availability
- QAM
- Beamforming
- MIMO
- MU-MIMO
- Frame Aggregation
- Error Correction

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Air tight 11ac webinar series session 2 - 11ac feature deep dive - june 2014 Presentation Transcript

  • 1. © 2014 AirTight Networks, Inc. All rights reserved. 802.11ac Feature Deep Dive MatthewSMullin RAFerruolo Blog.airtightnetworks.com@MatthewSMullin @RAFerruolo
  • 2. © 2014 AirTight Networks, Inc. All rights reserved. Agenda • 11ac Feature/Benefit Review • Dear FCC, etc. - More 5 GHz Channels Please • What the heck is QAM? • Beamforming Demystified • Good Old Fashion MIMO • MU-MIMO Magic • Frame Aggregation Broken Down • Forward Error Correction • Tres Dynamic Channel Width 2
  • 3. © 2014 AirTight Networks, Inc. All rights reserved. 3 11ac Features and Benefits Feature Benefits 11ac Channel Width Quadruple Throughput 20, 40, 80, 80+80, 160 MHz QAM Encoding More Bits/MHz 16, 64, 256 QAM Spatial Streams Double Throughput 8 Beamforming Higher Data Rates & Range (Standardized) Explicit Multi User MIMO Switch-like Wi-Fi MU-MIMO Frame Aggregation Greater MAC Efficiency A-MSDU size 11,426 Bytes A-MPDU size 1,048,576 Bytes Forward Error Correction Signal Strength Gain 1 – 2 dB for LDPC BCC LDPC Dynamic Channel Width Use Widest Channel Possible RTS/CTS Enhancements Bands Supported More Channels & Less Cluttered Spectrum 5 GHz Only
  • 4. © 2014 AirTight Networks, Inc. All rights reserved. 4 Dear FCC - More 5 GHz Channels Please • Channels shown as red may become available in not too distant future. Image source: http://www.samsung.com/global/business/enterprise-communications/news/latest- news/upcoming-new-wi-fi-technologies-ieee802-11ac
  • 5. © 2014 AirTight Networks, Inc. All rights reserved. 5 Channel Width Australia & US Brazil China Europe Japan Korea 20 MHz 9 17 12 4 8 25 40 MHz 4 8 5 2 4 12 80 MHz 2 4 2 1 1 6 160 or 80+80 MHz 1 2 1 0 0 3 Channel Availability without DFS Channels Includes TDWR (Terminal Doppler Weather Radar) channels 120, 124 and 128.
  • 6. © 2014 AirTight Networks, Inc. All rights reserved. 6 Channel Width Australia & US Brazil China Europe Japan Korea 20 MHz 25 28 16 19 23 25 40 MHz 12 14 8 9 11 12 80 MHz 6 7 3 4 5 6 160 or 80+80 MHz 3 3 1 2 2 3 Channel Availability with DFS Channels Includes TDWR (Terminal Doppler Weather Radar) channels 120, 124 and 128.
  • 7. © 2014 AirTight Networks, Inc. All rights reserved. Quadrature Amplitude Modulation Source: Wikipedia - http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation 7 Amplitude Modulation and Phase (Time) Shift Constellation Diagram
  • 8. © 2014 AirTight Networks, Inc. All rights reserved. 8 More Bits per MHz: 64-QAM vs. 256-QAM As constellations become denser higher signal strength and SNR are required to decode the data properly. Constellation Diagrams
  • 9. © 2014 AirTight Networks, Inc. All rights reserved. QAM Analogy 9 64-QAM 256-QAM Phase and amplitude steer the dart.
  • 10. © 2014 AirTight Networks, Inc. All rights reserved. 10 Explicit Beamforming: Higher Client Data Rates • Uses NDP (Null Data Packets) sounding frames • Clients respond with channel state • Channel state includes DSP, antenna and RF properties • AP uses channel state to calculate steering matrix • Steering matrix is used to determine amplitude and phase (time) parameters of the transmission • Single spatial stream is transmitted over multiple antennas • Objective is to create constructive interference at the receiver SNR
  • 11. © 2014 AirTight Networks, Inc. All rights reserved. 11 Explicit Beamforming: Potential Gains Client type Spatial Streams Potential Gain Phone e.g. Galaxy S5 1 Up to 7 dB Tablet e.g. Galaxy Tab Pro 1 Up to 7 dB Tablet e.g. Surface Pro 3 2 Up to 3 dB Laptop e.g. MacBook Air 2 Up to 3 dB Laptop e.g. MacBook Pro 3 Negligible Potential Gains for a 3 Spatial Stream AP
  • 12. © 2014 AirTight Networks, Inc. All rights reserved. 12 Beamforming Analogy Waves crests combining resulting in a stronger wave
  • 13. © 2014 AirTight Networks, Inc. All rights reserved. 13 Beamforming Oversimplified Dark blue wave is transmitted at the same time as the light blue wave. Dark blue wave is transmitted before the light blue wave. Antenna 2Antenna 1 Antenna 1 Antenna 2
  • 14. © 2014 AirTight Networks, Inc. All rights reserved. 14 MIMO Example 1 • With an 80 MHz channel the max data rate is 1.733 Gbps, with an expected max throughput rate of approximately 1 Gbps • Puts all 4ss of the AP to good use • Enables full capacity of the AP and channel
  • 15. © 2014 AirTight Networks, Inc. All rights reserved. 15 MIMO Example 2 • With an 80 MHz channel the max data rate is 433 Mbps, with an expected max throughput rate of approximately 260 Mbps • Uses only 1ss of the AP’s 4ss • Effectively only use ¼ of the AP’s throughput potential
  • 16. © 2014 AirTight Networks, Inc. All rights reserved. 16 MU-MIMO: Efficient Use of AP Radio/Channel • With an 80 MHz channel the aggregate max date rate is 1.733 Gbps • However, the max aggregate throughput is expected to be somewhere between 400 – 600 Mbps • Enables AP to be used more efficiently and supports greater channel capacity when clients support fewer spatial streams than the AP
  • 17. © 2014 AirTight Networks, Inc. All rights reserved. 17 MU-MIMO Magic • Downstream only • Supports up to 4 clients simultaneously • AP uses channel state from individual beamformees to calculate a composite steering matrix • Composite steering matrix is used to determine amplitude and phase parameters of the MU- MIMO transmission • Relies on APs ability to create beams (constructive interference) in combination with null beams Null Beam Beam
  • 18. © 2014 AirTight Networks, Inc. All rights reserved. 18 MU-MIMO Considerations • AP transmit power is shared amongst the group in a MU-MIMO transmission. • Null beams raise the noise floor. • Sustaining high per client data rate is more challenging with MU- MIMO. • Clients need to be spatially differentiated • Channel state measurements consume airtime • Unlikely the 256-QAM enabled MCS rates (MCS-8 and MCS-9) will be used that often with MU-MIMO.
  • 19. © 2014 AirTight Networks, Inc. All rights reserved. 19 Frame Aggregation Broken Down MAC Layer Aggregation • Frame aggregation is a technique of combining multiple MPDUs or MSDUs. • Makes 802.11 more efficient by minimizing the time lost to 802.11 protocol overheads, such as: • Contention process • Interframe spacing • PHY level headers (Preamble + PLCP) • Acknowledgment frames • A key difference between A-MSDU aggregation and A-MPDU aggregation is that A-MPDU aggregation happens after the MAC header encapsulation process.
  • 20. © 2014 AirTight Networks, Inc. All rights reserved. 20 A-MPDU Aggregation Image source: EE Times - http://www.eetimes.com/document.asp?doc_id=1278239 A-MPDU - Aggregated MAC Protocol Data Unit • Multiple MPDUs into a single aggregated MAC frame • Uses block acknowledgements or BlockAcks • Retransmissions are limited to specific subframes that were not received. • 802.11ac specifies that every 802.11ac transmission to be sent as an A-MPDU aggregate.
  • 21. © 2014 AirTight Networks, Inc. All rights reserved. 21 A-MSDU Aggregation Image source: EE Times - http://www.eetimes.com/document.asp?doc_id=1278239 A-MSDU - Aggregated Multi Service Data Unit • Multiple MSDUs destined for the same receiver are concatenated in a single MPDU. • Each original frame becomes a subframe within the aggregated MAC frame. • Only MSDUs of the same Access Class can be aggregated. • Cannot be used for broadcast & multicast.
  • 22. © 2014 AirTight Networks, Inc. All rights reserved. 22 Frame Aggregation Analogy Without Aggregation With Aggregation
  • 23. © 2014 AirTight Networks, Inc. All rights reserved. 23 Forward Error Correction BCC - Binary Convolutional Code • Required LDPC – Low Density Parity Check • Optional • Potential Benefits: • Effective gain of 1 – 2 dB over BCC • Enable MCS-8 and MCS-9 (256-QAM rates) at greater distances • Increase data rates • Reduce transmission times • Improve power savings • Low density refers to the relatively fewer 1s, compared to 0s needed for the parity check matrix.
  • 24. © 2014 AirTight Networks, Inc. All rights reserved. 24 Dynamic Channel Width • Objective is to use widest possible channel to transmit. • RTS/CTS is used to determine when channel bandwidth is clear. • 802.11a transmissions (20 MHz) are replicated as needed (e.g. 80 MHz channel would require 4 separate RTSs) • Devices addressed by the RTSs respond with CTSs for the free/usable 20 MHz channels.
  • 25. © 2014 AirTight Networks, Inc. All rights reserved. 25 Staggered Primary Channels 20 MHz Primary AP1 40 MHz 40 MHz 80 MHz 80 MHz 160 MHz 20 MHz Primary AP2 AP1 AP2 Channels 100 104 108 112 116 120 124 128
  • 26. © 2014 AirTight Networks, Inc. All rights reserved. 26 Dynamic Bandwidth - Transmissions Over Time 40 40 4040 80 80 20 20 80 20 20 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 Ch. 40 Ch. 44 Primary Ch. 48 Ch. 36 Primary AP1 AP2
  • 27. © 2014 AirTight Networks, Inc. All rights reserved. AirTight Networks 802.11ac APs Dual radios • Radio 1—802.11a/n/ac, 3x3:3, 5 GHz • Radio 2—802.11b/g/n, 3x3:3, 2.4 GHz Connectors • LAN 1—GigE/802.3af PoE • LAN 2—GigE/Wired Backhaul • Power—12 VDC • Console—RJ45 • Antenna—6 RSMA (Model C-75-E only) Benefits • Best price/performance • Industry’s only 11ac WIPS solution • Low power consumption (No feature sacrifice using 802.3af PoE) • Uses existing infrastructure (No costly upgrades to 802.3at required) Model C-75-E External antennas Model C-75 Internal antennas 27 #11acDeepDive
  • 28. © 2014 AirTight Networks, Inc. All rights reserved. Additional Resources www.airtightnetworks.com/11ac 802.11ac Data Sheets For C-75 and C-75-E Access Points 802.11ac White Paper Essential Considerations 802.11ac Migration Qualifying and Planning Questions 28
  • 29. © 2014 AirTight Networks, Inc. All rights reserved. Session 1: Intro to 11ac Session 2: 11ac Feature Deep Dive Session 3: Is 11ac Right for Your Network? Session 4: 11ac Deployment Best Practices Session 5: 11ac Channel Capacity Planning Session 6: 11ac Network Optimization 11ac Webinar Series
  • 30. © 2014 AirTight Networks, Inc. All rights reserved. Thank You! Send inquiries to Ask@airtightnetworks.com Next webinar: Tuesday, July 23rd, 8am & 6pm Pacific. “Is 802.11ac Right for your Network.” 30 @AirTight AirTight NetworksBlog.airtightnetworks.com