IWR6843AOPEVM: MIMO scheme

Tai Fei

Prodigy 10 points

Part Number: IWR6843AOPEVM

Hello,

I have used the mmWave_Demo_Visualize_3.5.0 generated several configurations for the sensor IWR6843AOPEVM.

But I do not know how to recognize which kind of MIMO multiplex scheme is used for specific configuration: TDM or BPM

Below is a setting of 4Rx-3Tx

% ***************************************************************
% Created for SDK ver:03.05
% Created using Visualizer ver:3.5.0.0
% Frequency:60
% Platform:xWR68xx_AOP
% Scene Classifier:best_range_res
% Azimuth Resolution(deg):30 + 30
% Range Resolution(m):0.044
% Maximum unambiguous Range(m):9.02
% Maximum Radial Velocity(m/s):1.21
% Radial velocity resolution(m/s):0.16
% Frame Duration(msec):100
% RF calibration data:None
% Range Detection Threshold (dB):15
% Doppler Detection Threshold (dB):15
% Range Peak Grouping:enabled
% Doppler Peak Grouping:enabled
% Static clutter removal:disabled
% Angle of Arrival FoV: Full FoV
% Range FoV: Full FoV
% Doppler FoV: Full FoV
% ***************************************************************
sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 15 7 0
adcCfg 2 1
adcbufCfg -1 0 1 1 1
profileCfg 0 60 287 7 57.14 0 0 70 1 256 5209 0 0 158
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 2
chirpCfg 2 2 0 0 0 0 0 4
frameCfg 0 2 16 0 100 1 0
lowPower 0 0
guiMonitor -1 1 1 0 0 0 1
cfarCfg -1 0 2 8 4 3 0 15 1
cfarCfg -1 1 0 4 2 3 1 15 1
multiObjBeamForming -1 1 0.5
clutterRemoval -1 0
calibDcRangeSig -1 0 -5 8 256
extendedMaxVelocity -1 0
lvdsStreamCfg -1 0 0 0
compRangeBiasAndRxChanPhase 0.0 1 0 -1 0 1 0 -1 0 1 0 -1 0 1 0 -1 0 1 0 -1 0 1 0 -1 0
measureRangeBiasAndRxChanPhase 0 1.5 0.2
CQRxSatMonitor 0 3 5 121 0
CQSigImgMonitor 0 127 4
analogMonitor 0 0
aoaFovCfg -1 -90 90 -90 90
cfarFovCfg -1 0 0 8.92
cfarFovCfg -1 1 -1.21 1.21
calibData 0 0 0
sensorStart

My questions:

1. With which attribute can I recognize the MIMO multiplex scheme?

2. I have also let the mmWave_Demo_Visualize generated a setting for 4Rx-1Tx, and the range resolution and speed resolutions and ambiguities stay unchanged. What is the cost by setting 3Tx? Which performance is then compromised by using 3Tx setting? Otherwise, we can also use the 3Tx-4Rx as default, since it provides the best angle performance.

3. There are many configuration attributes. Where can I find their descriptions about how I can interpret them and change them?

over 3 years ago

0 Angie Mitchell over 3 years ago

TI__Genius 10730 points

Hello,

I am going to look into questions 1 and 2 but I want to first answer #3 and ask a follow up so you can get started.

3. You can find more detailed information in the SDK user's guide located in the docs folder. You will find cfg command details on page 19.

TI 1. What are you trying to detect using radar?

Thank you,

Angie

0 Tai Fei over 3 years ago in reply to Angie Mitchell

Prodigy 10 points

Hello Angie,

many thanks for your reply. The questions #1 and #2 are important for my development.

As for your question, we are using this sensor for a robot indoor navigation.

Thank you,

Tai

0 Tai Fei over 3 years ago in reply to Angie Mitchell

Prodigy 10 points

Hi Angie,

I have checked the link MMWAVE-SDK Software development kit (SDK) | TI.com

In the docs folder, there are two files: "MMWAVE-SDK Software development kit (SDK) | TI.com" and "MMWAVE-SDK Software development kit (SDK) | TI.com". None of them tells me about the interpretation of the settings in the Configuration file. Do you have more documentation on this topic?

Many thanks.

Tai

+1 Muhammet Yanik over 3 years ago

TI__Intellectual 790 points

Hello.

Regarding your 1st question, the configuration you shared utilizes the TDM-MIMO scheme.

If you refer to the application report in the following link, TDM-MIMO needs sequential TX transmissions (i.e., in different time slots).

https://www.ti.com/lit/an/swra554a/swra554a.pdf?ts=1651167867691&ref_url=https%253A%252F%252Fwww.google.com%252F

In the chirp config you shared, the following command set configures this sequential transmission (only one TX is attached to each chirp). For BPM-MIMO, you need simultaneous TX transmissions (antenna mask: 011, 101, etc.) and the corresponding decoding scheme (please refer to the application report above and the BPM examples in the out-of-box demo).

chirpCfg 0 0 0 0 0 0 0 1 (antenna mask 001=1 means 1st TX)
chirpCfg 1 1 0 0 0 0 0 2 (antenna mask 010=2 means 2nd TX)
chirpCfg 2 2 0 0 0 0 0 4 (antenna mask 100=4 means 4nd TX)

Regarding your 2nd question, if you refer to the following application report, all the range/Doppler resolutions and ambiguities depend on the chirp parameters (sampling rate, slope, BW, inter-chirp time, number of chirps, etc.). Hence, the number of TX/RX antennas has no direct impact on such theoretical limitations.

https://www.ti.com/lit/an/swra553a/swra553a.pdf?ts=1651167748436&ref_url=https%253A%252F%252Fwww.google.com%252F

However, the number of TX/RX antennas has an impact on various other parameters such as SNR, etc. Hence, the number of TX/RX antennas also affects the detection capability (please check 'Eq.(2) Range based on SNR' in the above application report). Besides, as you mentioned, the angular estimation accuracy depends on the number of TX/RX antennas. One important cost of using more TX antennas is more power consumption, more computation power (needs more processing for more antenna elements), and more memory (needs more storage area for the radar cube).

Best regards.

Muhammet

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IWR6843AOPEVM: MIMO scheme