Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

lwm — Wed, 28 May 2025 02:13:02 GMT

Hello，

Okay, I understand now. Thank you for your help and reply.

Regards

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

Elfving — Mon, 26 May 2025 07:36:30 GMT

Hi,

I am seeing this on my side as well, so I've asked the relevant R&D team, who confirms this.

In 7.8.140, the spec says that:

The values for Min_Procedure_Interval, Max_Procedure_Interval, Min_Subevent_Len,
and Max_Subevent_Len are recommendations to the Controller which it may ignore.

So this is what happened here. Though I understand that it can be confusing that the controller isn't using the parameters provided by the user. Another thing to note is that with max_procedure_count = 1, there is only one procedure, so procedure interval wouldn't matter. If there are any specific settings that you are trying to set I can help you try to get as close to those as the SDC would allow?

Regards,

Elfving

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

lwm — Wed, 21 May 2025 03:14:45 GMT

Hello,

I'm currently testing Channel Sounding on the nRF54L15 DK, using single-antenna configurations. Below are my observations:

Single-Antenna Configuration Tests:

Test Configuration 1 & 2:

Configuration 1

Configuration 2

+ subevent_length becomes 21334 µs

+ procedure_interval becomes 14
Test Configuration 3:

+ subevent_length = 20000 µs (matches configuration)

+ procedure_interval = 5 (matches configuration)

Even in single-antenna mode, there are still mismatches between the configured and actual parameters, although the behavior is more consistent and predictable.

Key Observations:

The maximum subevent_length in single-antenna mode appears to be around 21334 µs, which aligns with the BLE specification. A subevent can have up to 160 steps, consisting of 3 mode 0 steps and the rest in mode 2. Based on timing calculations, this fits within the 21334 µs limit. However, in four-antenna configuration, the maximum subevent_length observed is only around 32938 µs, which supports only about 105 steps—far below the 160-step limit. I verified this via the subevent_result_cb callback. It's unclear why the limit is more restrictive in the four-antenna scenario.
The procedure_interval seems to be capped at 14, regardless of the configured value. I couldn’t find any reference to this limitation in the BLE specification, so I would like to understand if this is an SDK constraint or hardware-related.
The default event interval appears to be 30ms-50 ms

and since the subevent_length is usually around 20 ms, it seems feasible to fit a full procedure within a single event interval. However, the default configuration uses 2 event intervals per procedure. I’m not sure why this design choice was made and whether it can be modified

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

Elfving — Tue, 20 May 2025 11:40:28 GMT

Hi,

Thanks for reporting this. Are you seeing this with other antenna configurations as well, like with one antenna path?

Regards,

Elfving

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

lwm — Fri, 16 May 2025 13:03:57 GMT

Hello,

I'm currently testing the Channel Sounding feature on the nRF54L15 DK, using the nRF Connect SDK v3.0.1.

I made several modifications to the official channel_sounding_ras_initiator example for testing purposes. Specifically, I changed the antenna configuration with the following setting:

.tone_antenna_config_selection = BT_LE_CS_TONE_ANTENNA_CONFIGURATION_A4_B1

This sets the system to use 4 antennas. I then tested the behavior under different timing parameter configurations. Here are my observations:

Default Configuration:

Using the default procedure parameter values, I noticed that the subevent length in the actual result does not match the expected value.
Modified min_procedure_interval and min_subevent_len:

after adjusting these two parameters, the resulting procedure interval does not match the configuration.

3.Modified min_procedure_interval only:

The procedure interval still does not reflect the value I set.

From my testing with SDK v3.0.1, it appears that the Channel Sounding procedure parameters cannot be configured to match the manually set values.

RE: Unable to Effectively Configure Procedure Parameters in Channel Sounding on nRF54L15 DK

Elfving — Wed, 14 May 2025 12:44:32 GMT

Hi,

There definitely might be big changes in regards to how these parameters work in between the different NCS versions. Between the major releases (ie. 2.9 -> 3.0) there can be changes in the API as well.

I would also recommend not working on the main branch, as that might not be stable.

Could you confirm that you are seeing the same issue on NCS 3.0.1? If so I'll look into your questions.

Regards,

Elfving