WiFi FTM AX200/201/210 cannot set HE preamble

[VuTran86]

Hi,

I am using AX200, AX201 and AX210 to do some experiments with FTM. Can can get the FTM work with hostapd and iw. However, I notice that the tools/driver cannot transmit FTM packets using 802.11ax (HE preamble) format. I have modified the iw and driver to force it to use HE preamble but it always falls back to HT/VHT depending on 2.4GHz/5GHz band. Could you please share any suggestions or it is simply not supported by the hardware?

Kind regards,

Vu

[AlfredoS_Intel]

Hi Vutran86,

Thank you for posting in Intel Communities.

You have a very interesting question. Please allow us to ask the following information that we will use to check if your setup is supported by the hardware:

1. May we know what operating system and build of it are you using?

2. Would it be okay if you share more details regarding the project?

3. How did you monitor or determine that there are no FTPM packets transmitted on 802.11ax?

4. How did you modify the IW and driver to force use HE preamble?

Best Regards,

Alfred S

Intel® Customer Support Technician

[VuTran86]

Hi Alfred,

1. I am using Ubuntu 20.04, kernel 6.5.0-35-generic

2. I am trying to evaluate if FTM can benefit from finer CSI (256 samples) in 802.11ax compared with other PHY format such as 802.11n/ac at 20MHz bandwidth (20MHz bandwidth is more widely supported in many cases)

3. I use a third Intel WiFi card (AX210) to sniff the channel. The hostapd uses AX201 at channel 6 (2.437GHz/20MHz) as it seems the card does not support HE 20MHz in 5GHz band. The station is an AX200 pcie. I used Ubuntu 20.04 on all machines. In the tcpdump (monitor mode) I can see that ping packets are transmitted in 802.11ax format (at 20MHz bandwidth). However, the FTM request and response are transmitted in 802.11n.

4. In IW source  code, it does not support explicit setting for HE preamble, I added HE preamble in. In the iwlwifi backport driver (core88), it hardcodes preamble based on bandwidth. I changed it and only use IWL_LOCATION_FRAME_FORMAT_HE (function iwl_mvm_ftm_target_chandef_v2 in ftm-initiator.c -- I did similar modification in ftm-responder.c). I can trace it up to the call to send command to pcie and and format parameter is still PREAMBLE_HE. It seems that the firmware does not allow HE for FTM (Actually I didn't need to modify IW as I modified the driver already).

Thanks for your help.

vu

[AlfredoS_Intel]

Hi Vutran86,

Thank you for your quick response.

We will begin investigating on the inquiry that you raised; however, we would need your cooperation to provide Intel System Support Utility (SSU) logs from your system. You can download and run our Intel® System Support Utility from this page, https://www.intel.com/content/www/us/en/download/18895/intel-system-support-utility-for-the-linux-operating-system.html.

You can view the instructions on how to run this application on the readme file included on the download.

The steps below are from the readme file:

How to run ssu.sh from the terminal

==========================

1. Open Applications -> Accessories -> Terminal

2. From the current director, navigate to the current folder where the ssu.sh file resides. For example if you saved the ssu.sh to a folder called "SSU File" the command would be: cd "SSU File"

3. Run the ssu.sh file using this command: ./ssu.sh <parameter=0|1>  where 0 = off and 1 = enabled

4. Use the parameter definitions included in the readme to determine which parameter to use.

5. If no parameter is specified and only ./ssu.sh is run, it will capture all system information with the exception of 3rd party logs which must be specified. If no output file is specified, the SSU will write the output to file <sytemname>.txt.

Best Regards,

Alfred S

Intel Customer Support Technician

[VuTran86]

Hi Alfred,

I have tried the ssu.sh and attached the report below.

Thank you,

Vu

[AlfredoS_Intel]

Hi Vutran86,

Thank you providing those information.

Please allow us some time to check on this. 

We will get back to you as soon as we have findings regarding your inquiry.

Best Regards,

Alfred S

Intel Customer Support Technician

[AlfredoS_Intel]

Hi Vutran86,

Thank you for waiting for an update.

We need to get some information from you. Information that is sensitive, so we sent you an email, so you can comfortably reply with the information.

Many thanks for checking this message. We will wait for your reply.

Best Regards,

Alfred S

Intel Customer Support Technician

[AlfredoS_Intel]

Hi Vutran86,

Thank you providing those information.

Please allow us some time to check on this. 

We will get back to you as soon as we have updates on how to resolve your concern

Best Regards,

Alfred S

Intel Customer Support Technician

[AlfredoS_Intel]

Hi Vutran86,

Thank you for waiting for our update.

After further checking your concern, we would like you to refer you to this link, and the document, "Verification: Accuracy Evaluation of WiFi Fine Time Measurements on an Open Platform" pdf file again by refer Open WiFi FTM Tool, Software versions for open station, Configuring WiFi cards as FTM responding access points and Bandwidth effect. Wi-Fi 6 is backward-compatible with previous wireless standards and devices.

Additionally, we would like to ask if you are having issues on FTM with HT/VHT on 2.4 GHz.

If you are having issues even on HT/VHT on 2.4 GHz, please refer to this link. > FTMR (FTM Responder) Channel bandwidth and Channel band supported 802.11ac/n

Finally, if you are still having issues after referring to the provided links, please check with our Linux Distro for more details of FTM Settings.

Best Regards,

Alfred S

Intel Customer Support Technician

[AlfredoS_Intel]

Hi Vutran86, Vane,

We are just following up.

It looks like you need more time to assess the answers that we have provided.

Best Regards,

Alfred S

Intel Customer Support Technician

[VuTran86]

Hi Alfred,

Thank you for your support. However, my problem is with 802.11AX. I have been able to use FTM with 802.11AC/N since the beginning (I followed the links you mentioned since the beginning). The issue is that although I use both 802.11AX capable device (AX200 and AX210) as initiator and responder, they never transmits FTM packets using 802.11AX format (i.e. HE preamble -- even after I forced it to use HE preamble in the driver).

Kind regards,

Vu

[AlfredoS_Intel]

Hi Vutran86,

Thank you providing those information.

Please allow us some time to check on this. 

We will get back to you as soon as we have updates on how to resolve your concern

Best Regards,

Alfred S

Intel Customer Support Technician

[AlfredoS_Intel]

Hi Vutran86,

Thank you for waiting for our update.

As much as we would like to help you further, Intel wireless products are mainly a STA/ client solution on PCs. For other usages such as designing the FTM, please still suggest customer to check with Linux forums/ communities.

e.g. https://www.winlab.rutgers.edu/~gruteser/projects/ftm/Setups.htm

We look forward to your reply. Should we not get your reply, we will follow up after three business days.

Best Regards,

Alfred S

Intel Customer Support Technician