topic Re: Question about RAS transfer handling in app_localization vs app_localization_algo in MCUXpresso SDK

Question about RAS transfer handling in app_localization vs app_localization_algo

t_hosomi — Fri, 12 Jun 2026 08:23:34 GMT

Hi,

I am currently trying to use Channel Sounding on KW47, and I have been referring to the MCUXpresso SDK Documentation – Bluetooth Low Energy Channel Sounding Application Developers Guide. However, I am unsure whether it is necessary to implement the Ranging Service (RAS), so I would like to ask for your clarification.
Specifically, regarding the app_localization_algo common module, the document states:

"The app_localization_algo module is responsible for unpacking the data resulted from the CS Procedure and the RAS transfer. The module then passes it to the distance measurement algorithm to obtain the distance in meters, which is then communicated to the application."
"There is no other direct interaction between the application and this module. Its APIs are mostly used by the app_localization module."

Based on this description, I would like to clarify the following point regarding RAS transfer:

Is the RAS transfer automatically configured and handled within the app_localization module?
Or is app_localization only interacting with the app_localization_algo module, and for RAS transfer we need to separately implement it using the RAS APIs?

In other words, should the application rely entirely on app_localization for both CS procedure handling and RAS transfer, or is explicit integration of the RAS API required at the application level?
For reference, the relevant documentation page is:
https://mcuxpresso.nxp.com/mcuxsdk/26.03.00/html/middleware/wireless/bluetooth/doc/Bluetooth%20Low%20Energy%20Channel%20Sounding%20Application%20Developers%20Guide/topics/application_common_modules.html#app-localization-algo-common-module
I would appreciate your clarification.
Best regards,

Re: Question about RAS transfer handling in app_localization vs app_localization_algo

Christine_Li — Tue, 16 Jun 2026 10:32:27 GMT

Hi, @t_hosomi

Thanks for creating case to us.

Please allow me some time, I will check your detailed info and reply to you ASAP.

Best regards,

Christine.

Re: Question about RAS transfer handling in app_localization vs app_localization_algo

Christine_Li — Wed, 17 Jun 2026 10:01:51 GMT

Hi, @t_hosomi

Thanks for your patience and detailed info.

Please see below for my answer:

As you can see in the link you provided, RAS stands for Ranger Service. It is a separate service. `app_localization` actually calls the RAS profile interface to transfer data.

You can think of `app_localization` as part of the application code. RAS is called here, and also in other general application code. We recommend using `app_localization`.

`app_localization` implements the transfer of client-server (CS) data via RAS.

However, the application layer still needs to call basic interfaces, such as subscribing to profiles, enabling notifications, or indicators.

Please let me know whether is clear for you.

Best regards,

Christine.