DFS
European dual-band Keenetic models, i.e. those designed for the European market and having an EU or TR country code, use the DFS (Dynamic Frequency Selection) mechanism on the 5 GHz Wi-Fi network.
In many countries, regulatory requirements may limit the number of available channels in the 5 GHz band or impose additional restrictions on their use because the spectrum is shared with other technologies and services (e.g. used for satellite TV broadcasts, radar systems, aircraft, ship and military radars, and airfield weather radars, etc., which may be interfered with by wireless network transmitters). Wi-Fi networks operating in these bands must implement interference detection and avoidance measures to ensure that the emitted signal from Wi-Fi does not interfere with radars. European regulations require DFS to operate on channels 52–64, 100–112, 116–128, 132–140 in the 5250–5350 MHz and 5470–5725 MHz bands. The IEEE 802.11h standard addresses this requirement by adding DFS support and the TCP (Transmit Power Control) algorithm on each DFS channel.
There are two modes of DFS operation: In-band and Out-of-band (Zero Wait). More information can be found in the article Zero Wait DFS.
The IEEE 802.11h standard handles this requirement by adding DFS support and the TCP (Transmit Power Control) algorithm on each DFS channel.
Keenetic routers use the DFS mechanism on channels 52–140 in the 5 GHz frequency band, which is divided into several sections belonging to the UNII (Unlicensed National Information Infrastructure) frequency bands.
The UNII-1 band is intended for indoor operation.
UNII-2 and UNII-2e extended band for indoor and outdoor operation.
Range | Channel | Frequency (MHz) |
|---|---|---|
UNII-1 | 36 | 5180 |
40 | 5200 | |
44 | 5220 | |
48 | 5240 | |
UNII-2 DFS | 52 | 5260 |
56 | 5280 | |
60 | 5300 | |
64 | 5320 | |
UNII-2e DFS | 100 | 5500 |
104 | 5520 | |
108 | 5540 | |
112 | 5560 | |
116 | 5580 | |
120 | 5600 | |
124 | 5620 | |
128 | 5640 | |
132 | 5660 | |
136 | 5680 | |
140 | 5700 |
When working on a DFS channel, a router constantly monitors the used frequency for radar signals (interference, pulses). The CAC (Channel Availability Check) mechanism is used: if a radar signal is detected on the current channel, the router will free this channel and automatically switch to an alternative one. The channel on which the radar signal was detected will not be used for a certain period.
However, it should be remembered that in some countries, the 5 GHz band is not fully allocated to Wi-Fi routers, but only on the condition that no radars operate in the available frequency range.
Important
On DFS channels, the Keenetic router automatically disables 5 GHz Wi-Fi when a radar signal is detected. On channels 52–64, the time it takes for the Wi-Fi access point to stop working when a radar signal is detected is approximately 1 minute (65 seconds), and on channels 100–140, the time is 10 minutes (605 seconds).
Some router models support a 160 MHz channel width. In this case, please note that if 160 MHz is used, it may cause access limitation and speed reduction due to the channel width reduction.
