DFS (Dynamic Frequency Selection) capability for the 5GHz band and Radar Detection on nRF7002

[Miguel Roque]

Hi guys,

We have a device that is equipped with nRF7002 that is about to follow for certification. The laboratory sent us some questions due to the 5GHz band communication of the radio: 

• Does the device support DFS? Master or Slave?
• If slave, does it support Radar Detection?

I did a quick search on device datasheet and Nordic Support but very little answers... Based on this ticket (https://devzone.nordicsemi.com/f/nordic-q-a/95867/radar-detection-and-dfs-with-nrf7002) the device doesn't support Radar Detection, and when in active mode (softAP or WiFi Direct Mode) the radio guarantees to not interfere with any DFS band.

Also, according to European Commission documentation (5th joint cross-border R&TTE market surveillance campaign (2013) on WLAN 5 GHz): "DFS function is mandatory unless WLANs operate in 5150-5250 MHz band only or in slave mode with maximum e.i.r.p of less than 23dBm only". So should I assume that when operation as client device, the max power at 5GHz (acording to datahseet) is 16dBm and (without any major gain block) we are bellow the 23dBm, but my question is for the active mode... because the nRF7002 operates at sub-bands besides the 5150-5250MHz...

Thanks in advance for your help,

Best regards,

[ketiljo]

It's correct that the nRF7002 doesn't support DFS in any mode. So that prohibits the use of the nRF7002 as a AP (master) on channels that requires DFS. 

[Miguel Roque]

Hi ketiljo thank you for your reply! So when using the nRF7002 in AP (master) who is responsible to guarantees that non DFS channels will be used? The radio by itself, is it configurable by firmware or it simply is "hardwired" blocked?

Best regards,  

[ketiljo]

Note that AP support isn't enabled yet. But when this is in place, only the non-DFS channels will be offered as an AP. These depend on region. See https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/device_guides/working_with_nrf/nrf70/developing/regulatory_support.html for details of DFS channels.

i.e. the driver/firmware will reject an attempt to configure a non-DFS channel.

[Miguel Roque]

Thank you ketiljo! I'm clarified, thank you for your help!

[Chamith Koperahewa]

Hi, 

This was helpful but given that Access point mode is enabled, is DFS enabled for Wifi 5GHz? Polling information from the NRF7002 reports that it has DFS enabled for specific bands, please check the picture below.

If so

1. DFS is supported on NRF7002 especially for 5GHz, does it work as
   1. Primary device?
   2. Secondary device with radar detection?
   3. Secondary device without radar detection?
2. DFS threshold: Is it something that we can control?

Thank you