Why was the maximum advertisement data size reduced to 160 from 1650?

[h0293]

Hello,

It seems that between versions 22.120.0 and 22.130.0 of the Intel Wireless Bluetooth Driver, there was a reduction of the maximum extended advertisement data size from 1650 to 160.

When sending advertisement data that goes over this limit, the HCI commands will be rejected. When receiving advertisement data that goes over this limit, the data will be truncated by the controller and host will receive incomplete data.

The hardware IDs of the controller I used to reproduce this are: VID_0087, PID_0026.

I can reproduce the behaviour by downgrading and upgrading the driver and using the Windows Bluetooth Platform coupled with Wireshark to observe the commands being sent by the controller in response to the LE_READ_MAXIMUM_ADVERTISEMENT_DATA_LENGTH command sent by the host.

Was this a purposeful change? Are there any plans to increase the limit back to 1650?

[AndrewG_Intel]

Hello @h0293

Thank you for posting on the Intel® communities.

In order to understand better this scenario and provide the proper information, could you please confirm the following details?

1- What is the exact model of the Intel® Wireless/Bluetooth card?

2- Please elaborate more on the scenario. For instance:

• What is the Bluetooth device that you are using with the Intel® Bluetooth?
• How do you use the devices? what is the use case?
• Are you developing hardware or software using Intel® Wireless/Bluetooth cards?
• If you are not developing hardware with Wireless/Bluetooth, please confirm if the Intel® Wireless/Bluetooth card came pre-installed on the computer or if you replaced/integrated it into the system.
• Is this issue happening at home, office environment, or both?

3- Since you are referring to two previous versions of the drivers "22.120.0 and 22.130.0", do you know if the behavior is the same on the latest drivers (22.170.0 and 22.160.0)? Also, do you see the same behavior using the customized drivers from the computer manufacturer? (if applicable)

4- Run the Intel® System Support Utility (Intel® SSU) to gather more details about the system:

• Download the Intel® SSU and save the application on your computer
• Open the application, check the "Everything" checkbox, and click "Scan" to see the system and device information. The Intel® SSU defaults to the "Summary View" on the output screen following the scan. Click the menu where it says "Summary" to change to "Detailed View".
• To save your scan, click Next and click Save.
• Once you have saved the file (.txt file), please attach it to your reply.

To upload and attach a file, use the "Drag and drop here or browse files to attach" option below the response textbox.

Best regards,

Andrew G.

Intel Customer Support Technician

[h0293]

Hi Andrew,

Thanks for your response.

1. The card shows up as Intel(R) Wireless Bluetooth(R) in Device Manager. The only identifying information I can provide is the device hardware ID, which is: USB\VID_8087&PID_0026&REV_0002. It should be possible to deduce the make and model from here.

2. I'm currently researching some details in regards to the Bluetooth protocol and its usages. For this purpose I'm using my personal laptop that has the Intel Wireless Bluetooth adapter integrated into an internal usb port.

The current use case involves the laptop listening to the advertising data coming from remote devices. I'm observing the data that's communicated between the controller and the host by using the Microsoft Bluetooth Test Platform. When upgrading to the latest driver version (22.170.0), I noticed that data that was being advertised from a remote device was being truncated by the controller on the personal laptop. This wasn't happening before the driver upgrade.

After debugging for a while and installing different driver versions, I spotted the reported behaviour - i.e. the controller was reporting that the maximum extended advertising data size is now 160, down from 1650 on the previous driver version. It's also worth mentioning that I can reproduce the exact same behaviour on two other personal laptops, which contain the same Intel(R) Bluetooth Wireless(R) device as the first laptop.

3. Yes, the behaviour can be observed in all driver versions starting from 22.130.0, up until 22.180.0 (preview version within the Windows 11 Preview Insider build).

4. The requested information has been attached to this post.

Thanks again.

[AndrewG_Intel]

Hello h0293

Thank you for your response and for the details.

Please allow us to look into this and we will be posting back in the thread as soon as more information is available.

Best regards,

Andrew G.

Intel Customer Support Technician

[AndrewG_Intel]

Hello h0293

We are still working on this matter. However, we would like to gather some additional details that may include private information, so we are going to send you an email to the email address associated with your profile so you can reply with the information privately.

Best regards,

Andrew G.

Intel Customer Support Technician

[AndrewG_Intel]

Hello h0293

We appreciate the information provided via email. After reviewing it, we would like to inform you that we follow the Bluetooth standards and haven't received similar reports; therefore our recommendation is to check with your Original Equipment Manufacturer (OEM) or test the next Bluetooth release driver to be available soon.

Best regards,

Andrew G.

Intel Customer Support Technician

[AndrewG_Intel]

Hello h0293

We have not heard back from you so we will proceed to close this thread now. If you need any additional information, please submit a new question as this thread will no longer be monitored.

Best regards,

Andrew G.

Intel Customer Support Technician