4 ms·

How does a Wi-Fi chip know what country it's operating in to know what the relevant DFS channels are?

e2le 4y ago
It'll have a region set by the manufacturer in it's firmware. IEEE 802.11d-2001 also added country information to AP beacons and probes. Nearby access points will advertise a country code to each other. Hostapd and/or the Wi-Fi device firmware can take advantage of that. [1]: https://en.wikipedia.org/wiki/IEEE_802.11d-2001 https://en.wikipedia.org/wiki/IEEE_802.11d-2001 [2]: https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf Fun fact: Access points can also advertise a timestamp and timezone. [3]: https://openwrt.org/docs/guide-user/network/wifi/basic#bss_transition_management_frames_options_80211v https://openwrt.org/docs/guide-user/network/wifi/basic#bss_t...
Vecr 4y ago
It's either set by the user, or it's already set on the device based on the market the product is selling into. Phones have GPS though, so I'm not sure how that factors into it.
- sgtnoodle 4y ago
  It's usually programmed into an EEPROM inside the device. Nowadays for compliance reasons, the radio firmware may enforce it rather than the software driver.
mjg59 4y ago
APs are normally programmed based on the market they're sold into. Client devices receive information about which regulatory domain they're in from the AP they're connecting to.
- meltedcapacitor 4y ago
  Can't imagine mom and pop shop on aliexpress is programming APs individually based on the recipient address.
  - mjg59 4y ago
    There's no technical mechanism to prevent someone operating an AP inappropriately. That's more an opportunity to discover how effective your local enforcement agency is.
Roark66 4y ago
The brand I use has a drop down menu to select from. Also, regarding WiFi equipment. Finding out the quality of consumer WiFi gear is near impossible before buying, because of so many other factors affecting wifi performance (especially that I use mostly 2.4ghz). If anyone has a foolproof method for this please let me know.

e2le 4y ago

It'll have a region set by the manufacturer in it's firmware. IEEE 802.11d-2001 also added country information to AP beacons and probes. Nearby access points will advertise a country code to each other. Hostapd and/or the Wi-Fi device firmware can take advantage of that. [1]: https://en.wikipedia.org/wiki/IEEE_802.11d-2001 https://en.wikipedia.org/wiki/IEEE_802.11d-2001 [2]: https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf Fun fact: Access points can also advertise a timestamp and timezone. [3]: https://openwrt.org/docs/guide-user/network/wifi/basic#bss_transition_management_frames_options_80211v https://openwrt.org/docs/guide-user/network/wifi/basic#bss_t...

Vecr 4y ago

It's either set by the user, or it's already set on the device based on the market the product is selling into. Phones have GPS though, so I'm not sure how that factors into it.

sgtnoodle 4y ago
It's usually programmed into an EEPROM inside the device. Nowadays for compliance reasons, the radio firmware may enforce it rather than the software driver.

mjg59 4y ago

APs are normally programmed based on the market they're sold into. Client devices receive information about which regulatory domain they're in from the AP they're connecting to.

meltedcapacitor 4y ago
Can't imagine mom and pop shop on aliexpress is programming APs individually based on the recipient address.
- mjg59 4y ago
  There's no technical mechanism to prevent someone operating an AP inappropriately. That's more an opportunity to discover how effective your local enforcement agency is.

Roark66 4y ago

The brand I use has a drop down menu to select from. Also, regarding WiFi equipment. Finding out the quality of consumer WiFi gear is near impossible before buying, because of so many other factors affecting wifi performance (especially that I use mostly 2.4ghz). If anyone has a foolproof method for this please let me know.