Layman’s Guide to TxBF, MIMO and MU-MIMO WIRELESS PROPRIETARY AND CONFIDENTIAL Layman’s Guide to TxBF, MIMO and MU-MIMO GT Hill Chief Big Dog Ruckus Wireless gt@

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  • RUCKUS WIRELESS PROPRIETARY AND CONFIDENTIAL

    Laymans Guide to TxBF, MIMO and MU-MIMO

    GT HillChief Big Dog

    Ruckus Wireless

    gt@ruckuswireless.com

    @gthill

  • Poor adoption with 802.11n 802.11ac focuses on one implementation

    Universal industry focus

    NDP Sounding with explicit immediate compressed feedback

    2x2

    Access Point 1x1

    Client

    Signal

    Quality

    TxBF

  • 3

  • 4

    +3dB

  • 5

    +4.7dB

  • 6

    +6dB

  • 7

    12

  • 8

    12

  • 9

    12

  • 10

    12

  • o 3 / 4.7 / 6 dB gain vs. additional spatial streamoEach antenna can either

    reinforce the signal (TxBF) or

    add more data (spatial

    multiplexing) but never both at

    the same time.

    oEach additional spatial stream

    adds significantly more speed

    o3dB adds

  • 1 B

    itCan you hit this target?

  • 2 B

    its

    How about one of these?

  • 4 B

    its

  • 6 B

    its

  • 8 B

    its

  • o Improves efficiency by 33%

    oAdds complexity, requires higher

    SNR

    oEfficiency gain from modulation

    does not increase linearly

    256-

    QAM64-QAM16-QAM

    QPSKBPSK

    0 1

    01 11

    00 10

    100% gain (2x)

    100% gain (2x) 50% gain (1.5x) 33% gain (1.3x)

  • 18

    Uses only ONE antenna for transmit and receive

    802.11a/b/g

    Go Get Certified!

  • 19

    802.11n/ac

    Can use multiple antennas for transmit and receive

    Go

    Get

    Certified!Tx Rx : SS

    3 x 3 : 3

  • 20

    802.11n/ac

    Can use multiple antennas for transmit and receive

    Go

    Get

    Certified!Tx Rx : SS

    3 x 3 : 3

  • 21

  • oIncreasing the difference in perspective between each stream

    oHorizontal vs. vertical polarization

    oMultipath

    22

  • oRequires 11ac client(s) with TxBF feedback/support

    oCreates new challenges related to signal steering and isolation

    4x4:4

    Access Point

    4x4:4

    Access Point

    Multi-User MIMOmultiple clients at the same time

    Single-User MIMOone client at a time

  • oPeak to Average Power Ratio

    oTransmit power equalization

    oRate selection

  • oDelayed Acknowledgment (block ack)

    oData Queuing

    oSelecting MU groups

    oMaking the process efficientoSame size frames

    oSame data rate clients