Channel Sounding: counter-intuitive repetition behavior + non-configurable event interval (nRF54L15)

Hello,

we are developing a Channel Sounding application starting from the Nordic samples "Channel Sounding Initiator with Ranging Requestor" and "Channel Sounding Reflector with Ranging Responder" (SDK v3.3.0). We are using the nRF54L15 development board.

ISSUE 1 - CS_CHANNEL_MAP_REPETITION counter-intuitive behavior
Comparing two configurations, single channel map repetition (72 steps, repetition=1) gives better accuracy results than repetition=2 with the same number of steps, contrary to the expectation that more repetitions (= more IQ samples) should improve the estimate. This behavior was confirmed also in an obstacle-free LOS environment, across repeated tests.

Config A (repetition=1) - result:


Config B (repetition=2) - result:

Questions:

  1. Is this behavior plausible, or does it indicate a configuration error on our side?
  2. Which other parameters significantly affect accuracy and should be varied to verify a potential benefit from repetition>1?
  3. Any suggestions on how to set the CS parameters to obtain real benefits from multiple channel map repetitions?

ISSUE 2 - Event interval fixed at 2, not configurable
Regardless of the CS configuration set, the logs always show event interval = 2 after CS procedures enabled.

Why is this not controllable and does not go down to 1? This affects the procedure duration and therefore indirectly the power consumption of the application, so we would like to be able to reduce it.

We remain available for any further details, thank you in advance.

Emilio

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  • Yes. I haven't modified the algorithm already used in the Nordic examples. I've only modified the code to record the distance in a more practical way.

    I therefore confirm that I'm using the algorithm found in "Channel Sounding Initiator with Ranging Requestor" and "Channel Sounding Reflector with Ranging Responder" (SDK v3.3.0).

    Regarding point 2, thanks for the clarification.

    Emilio

  • Hi Emilio, and thanks for the patience, as well as the report.

    I am sorry to say that our algorithms have not been tested with Channel Map Repetition higher than 1, so we can't guarantee that they work as expected. The algorithm as a whole is also for now experimental, and should not be used for validation or production quality projects.

    In order to use an algorithm that is both production ready, as well as providing higher accuracy, I would recommend checking out 3rd party algorithms. I believe our sales managers can get you in contact with someone who can supply this. Let me know if you want his/her contact info.

    Regards,

    Elfving

Reply
  • Hi Emilio, and thanks for the patience, as well as the report.

    I am sorry to say that our algorithms have not been tested with Channel Map Repetition higher than 1, so we can't guarantee that they work as expected. The algorithm as a whole is also for now experimental, and should not be used for validation or production quality projects.

    In order to use an algorithm that is both production ready, as well as providing higher accuracy, I would recommend checking out 3rd party algorithms. I believe our sales managers can get you in contact with someone who can supply this. Let me know if you want his/her contact info.

    Regards,

    Elfving

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