Question about RAS transfer handling in app_localization vs app_localization_algo

[t_hosomi]

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%2...
I would appreciate your clarification.
Best regards,

[Christine_Li]

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.

[Christine_Li]

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.

[t_hosomi]

Hi @Christine_Li,

Thank you for your response.

Based on your explanation, my understanding is that although RAS is also handled within app_localization, the basic interface still needs to be called and configured from the application layer.

However, in the SDK sample codes such as digital_key_car_anchor_cs and digital_key_device_cs, it appears that the Ranging Service configuration is not explicitly called from the application layer, as described in the “Ranging Service common module” section of the documentation.

Is my understanding correct that these samples, as they are, cannot be used directly (i.e., they may not function correctly or may not achieve improved ranging accuracy) without additional RAS configuration at the application level

Best regards,

[Christine_Li]

Hi, @t_hosomi 

Thanks for your reply.

To avoid misunderstandings, let me change another word.

RAS is not handled within app_localization, but rather that RAS is a separate service. 

app_localization need to call RAS to transfer CS data.

The samples are not necessarily unusable as-is. However, it should not be assumed that `app_localization` automatically handles all RAS/profile-level setup. When integrating the functionality into a custom application, it is still necessary to verify that the required application-layer procedures—such as profile subscription and enabling notifications/indications—have been properly implemented. Otherwise, the RAS data path may not function as intended.

Hope it is more clear for you.

If still anything is not clear, please let me know.

Best regards,

Christine.

[t_hosomi]

Hi @Christine_Li,

Thank you for your response.

I understand that RAS is an independent service.

To transfer CS data (i.e., to use RAS) within app_localization, is my understanding correct that it is necessary to additionally implement the steps described in the “Ranging Service common module” section of the related documentation, as well as in the wireless_ranging SDK sample—specifically, that “the application layer still needs to call basic interfaces, such as subscribing to profiles, enabling notifications, or indicators”?

Best regards,

[Christine_Li]

Hi, @t_hosomi 

Yes, you are right.

Best regards,

Christine.