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IWR1443: Questions about TDM MIMO

Naoki Kawada
Guru 19890 points
Part Number: IWR1443

Hello,

My customer would like to know TDM-MIMO technology with IWR1443.

1. Is it possible for users to use 3 TDM on 3 Tx Antennas to have higher azimuth resolution than 2TDM mode. 2TDM has been explained in your MIMO application report. But how about 3 TDM ?

2. Let`s say, we have 3 antennas, Tx1, Tx2 and Tx3. And Tx2 is for the elevation. In 2 TDM mode, I`m wondering if Tx2 is always radiated, for example, Tx1+Tx2 for 1st slot --> Tx2+Tx3 for second slot --> Tx1+Tx2 for 3rd slot, ....

3. Do you have a simple example of CLI command sequence to get the IWR1443BOOST worked with 2TDM-MIMO ?

Best Regards,

NK

  • 0
    TI__Mastermind 30405 points

    Hi Naoki-san,

    1. You can use all 3TX for Azimuth but you will need a different Antenna Design (with the center TX antenna at the same level as the other TX antennas).

    2. If you look at the 3D chirp profile C:\ti\mmwave_sdk_02_01_00_04\packages\ti\demo\xwr14xx\mmw\profiles\profile_3d.cfg,

    chirp 0 is transmitted on TX 0 (TX bitmask = 1)

    chirp 1 on TX 2 (TX bitmask = 4 )

    chirp 2 on TX 1( TX bitmask = 2 (i.e. middle TX antenna for elevation)

    profileCfg 0 77 7 7 58 0 0 68 1 225 4500 0 0 30
    chirpCfg 0 0 0 0 0 0 0 1
    chirpCfg 1 1 0 0 0 0 0 4
    chirpCfg 2 2 0 0 0 0 0 2

    (Please refer to the SDK user guide, section configuration file format for details on these commands and parameters)

    3. Please look at the sample 2 TX TDM MIMO profile provided in mmWave SDK 2.1.0.4 at C:\ti\mmwave_sdk_02_01_00_04\packages\ti\demo\xwr14xx\mmw\profiles\profile_2d.cfg

    Here chirp 0 is transmitted on TX 0 and Chirp 1 is transmitted on TX 2

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    Guru 19890 points

    Hello Nitin,

    Thank you for your answers.

    2. Let`s say, we have 3 antennas, Tx1, Tx2 and Tx3. And Tx2 is for the elevation. In 2 TDM mode, I`m wondering if Tx2 is always radiated, for example, Tx1+Tx2 for 1st slot --> Tx2+Tx3 for second slot --> Tx1+Tx2 for 3rd slot, ....

    Please let me confirm this part again. The datasheet suggests "Three Transmit Channels (Two Can be Used Simultaneously)". I think i have been confused by this and thought the above scenario. Does the datasheet statement mean actually BPM-MIMO ?

    And considering the answer for 1 in the above, in theory, can i assume we can achieve approximately 9.5° (2/N * 180/pi, where N=12 virtual antenna) for azimuth resolution by using 3 TDM MIMO (with customized and flattened Tx  antenna design) ?

    Best Regards,
    NK

  • 0 in reply to Naoki Kawada
    Guru 19890 points
    Hello, Do you have any response on this? Best Regards, NK
  • 0 in reply to Naoki Kawada
    Guru 19890 points

    Sorry to bother you, but i`m still waiting for your reply.

    Best Regards,
    NK

  • 0 in reply to Naoki Kawada
    TI__Mastermind 30405 points

    Hello Naoki-San

    1. Yes,  the statement in the data sheet implies that at max, any two transmitters can be operated simultaneously, which will be useful in BPM-MIMO or increasing TX power to get higher detection range.

    2. That's correct,  if you use all 3 transmitters for azimuth in  TDM- MIMO configuration,  the theoretical angular resolution will be 2/N  or 1/6 radians which is 9.58 degrees.

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    Guru 19890 points

    Hello Nitin,

    Thanks for your response. I understood. I close the thread now.

    Best Regards,
    NK