Channel Sounding - Speed and Multiple Devices

[MatthewP]

Hi,

We are evaluating BLE Channel Sounding for indoor localization of small mobile robots. We need 2D localization within the room, so we would need to measure the distance to multiple anchors.

We have some basic questions about this:

• How fast can a single distance measurement be performed? I've seen numbers in the range of 100ms?
• Is it possible to be paired with multiple anchors and perform BLE CS sequentially without having to establish a new connection each time?
• When can we expect an update of the SDK with CS support?

Thank you very much for your response.

BR, Matthew

[MatthewP]

Hi Simon,
thank you for your detailed response. Are there any news regarding question 1?

Also, w.r.t to your answer:
1. Since the calculation of the distance is done in the application layer, would it be possible to switch between each device for every ACL interval and aggregate the results on a per-device basis? For example, use 2 ACL intervals for device 1 and save its data, the next 2 ACL intervals for device 2, ... In the meantime, use the data from the steps for each device to calculate the distance more or less simultaneously.
2. Interesting note about scheduling conflicts. Even after reading quite a bit about ACL connection events, intervals, etc. I'm still not a 100% sure how it works. Shouldn't it be fine if I set the procedure count to 1 in the previous example and then go through the connected devices one-by-one?

Additional small question: am I correct in assuming that the nRF54L15 does not support the LE 2M 2BT PHY? I didn't find any mentions in the datasheet.

Thank you again for your great help and best regards,
Matthew

[Simonr]

Hi

1. Not much new I'm afraid. You will get some measurements with 7.5ms, but not enough to do accurate distance measurement. How many samples are needed for an algorithm to be accurate enough is dependent on the algorithm and the accuracy requirement. Do you have an idea of how many samples you'll need for your algorithms? If you don't we can suggest some values, but we need to know what your requirements are is most important.

2. Going through the devices one by one sounds okay, but the effective ACL interval will be higher before you come back around to the same device again here.

There is no support for the LE 2M 2BT PHY on the nRF54L15, that's correct.

Best regards,

Simon