Testing MIMO? You Only Have a Few Options…

If you are testing Multiple Input, Multiple Output (MIMO) devices beyond 2×2 then your test solutions get fairly limited, in fact there are really only three:

1. Litepoint NxN system

  • Using the IQnxn hardware and IQwave software
  • You’ll need one IQnxn unit/module per antenna (i.e. 3 units for a 3×3 MIMO) at a cost of around $US 50,000 per

    Advantages

    • Built-in generator (VSG) and analyzer (VSA) in one instrument
    • Great insight into device behavior with detailed displays
    • API available (i.e. for MATLAB)
    • Timely updates as standards get updated
    • Ability to incorporate the Device Under Test (DUT) MAC address into the preamble – this is needed for putting most devices into test mode (without actually connecting to an access point) for Packet Error Rate (PER) testing

    Challenges

    • One of the more expensive solutions on the market (but then there’s only three)
    • Dedicated tester, limited usefulness for any other applications
    • Can be a challenge to get technical and sales support

    Link(s)

    http://www.litepoint.com/content/view/105/140/

    2. Agilent Oscilloscope w/89601 VSA Software

    • Required options 200 (Basic Vector Analysis) and 300 (Hardware Connectivity) to work with any hardware platform including oscillloscopes
    • Option B7Z required for 802.11n, if you also will be testing a/b/g then you’ll also need opt. B7R
    • You’ll need at least 6 GHz of bandwidth and at least 20GS/s (I recommend 40 Gs/s) if your DUT operates in the 5 GHz band (i.e. DSO90804A or a used DSO80604B)
    • Note: Tektronix also offers spectrum analysis software for their high-end oscilloscopes called SignalVu; however, it does not offer 802.11 demodulation nor the ability to assign individual displays to each channel

    Advantages

    • 4 independent channels – ability to view spectrum, amplitude, phase and demod on all channels in one view
    • Ability to add demodulation options to the 89601A VSA software (i.e. WiMAX, LTE, etc.)
    • General purpose instrument – possible to use for a variety of other applications

    Challenges

    • Oscilloscopes are not optimized for RF performance
    • Need to use external generator for receiver testing (i.e. PER)
    • Dealing with licensing and installation

    Link(s)

    Oscilloscopes: http://www.home.agilent.com/agilent/product.jspx?nid=-536902447.0.00&lc=eng&cc=US

    89601A VSA Software: http://www.home.agilent.com/agilent/product.jspx?nid=-35484.0.00&cc=US&lc=eng

    3. Agilent N4010A

    • Requires option 103 (802.11a/b/g) and Option 108 (802.11n)
    • Can test up to 4×4 MIMO using the N4011A expansion module

    Advantages

    • The least expensive of the options for testing up to 4×4 MIMO
    • Offers full suite of pre-loaded/configured tests for both transmit and receive (built-in VSG/VSA)

    Challenges

    • Appears to be targeted more to manufacturing, does not offer the level of insight/debugging as the Oscilloscope or Litepoint approach
    • Need to use external generator for receiver testing (i.e. PER)
    • Dedicated tester for WLAN, Bluetooth and Zigbee only – limited usefulness as a general purpose instrument

    Link(s)

    N4010A: http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=736843&nid=-536900799.536908552.00&id=736843

    N4011A: http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-536900799.382855&pageMode=OV

    Some great demo/tutorial videos: http://www.home.agilent.com/agilent/editorial.jspx?cc=US&lc=eng&ckey=1426165&nid=-34317.536883549.02&id=1426165

    Conclusion

    For those testing MIMO beyond 2×2, the options really do slim down to these three that I’ve been able to use/evaluate over the years. All of these allow for common transmitter measurements (i.e. EVM, I/Q parameters, center frequency, bandwidth, power, ACPR, demodulate to bit leve, etc.).

    If you know of any other solutions for testing 3×3 MIMO feel free to post them in the comment section.

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    One Response to Testing MIMO? You Only Have a Few Options…

    1. Anonymous says:

      The Rohde and Schwarz RTO1044 Oscilloscope with K10x software options can be used to perform tests on 4X4 MIMO LTE UL and DL.

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