Wifi dual mode 2,4Ghz and 5Ghz

  • Currently using pfSense 2.1.2 on the APU1C. I am evaluating the 2.2 ALPHA and i try to understand how to use a miniPCI Express wifi card like the WLE200NX to have both 2,4Ghz and 5Ghz radio enabled at the same time :

    • may i need to create both interfaces under the Wireless pane into the Interfaces menu with one running bgn 2,4Ghz and the other an 5ghz ?
    • or i need to add a new interface on the Interfaces assignments for one radio like 2,4Ghz and add the other radio on the Wireless pane or Interfaces assignments ?

    I am confused how to setup this properly with the correct pfSense-FreeBSD behavior. My first test force in any case to have the same radio running for all interfaces created…

    Thanks in advance for your help.



  • You need two wireless cards in order to operate on 2.4GHz and 5GHz simultaneously.
    Simply assign the two cards as you would assign any other network card.

  • Ok, thank you.
    This why on the Enterprise AP with external antennas running 3x3 MIMO you have in fact 6 antennas (3x for 2,4ghz and 3x for 5Ghz) ?

  • Yes that is the reason.
    Often if you have consumer grade dual-band APs with only 3 antennas, then these antennas are only for 5GHz. The 2.4 GHz antennas are in such devices small onboard antennas (basically a wire on the circuit board).
    This is because you have 6db less attenuation over the air for the same distance on 2.4 than on 5.

  • In theory, the equivalent free space path loss exponents for the ISM and U-NII bands would be about 7 dB in favor of the ISM band for all distances.  In actual measurement, these tend to be about 4 dB, again in favor of the ISM band.  That 3 dB difference is directly attributable to the fact that for a given antenna aperture, that antenna is electrically "larger" to a signal at 5GHz than one at 2.4GHz.

    From memory, over a 1-10 m range the best fit path loss exponents for the two bands are both 1.9 for line-of-sight geometries.  In theory, this can't be better than 2.0 for LOS in a clear field.

    For non-LOS geometries, the best fit path loss exponents determined from actual measurements over a 3-14 m range are 3.7 and 4.6 for ISM and U-NII bands, respectively.

    Propagation losses caused by one wall are 4.2 dB greater for the U-NII bands than for the ISM band.

    Loss through flooring is typically 1.5 dB greater for the U-NII bands.

    None of this even begins to account for the overly-noisy spectrum in the ISM band.  When the noise floor is -88dBm for the ISM band, and still -105 dBm for the U-NII bands, you'll still be ahead running 802.11a over 802.11g.

    Note that 802.11ac (NO SUPPORT IN ANY VERSION OF PFSENSE) will be 3-6 dB better than any 802.11n mode (2.2 pfSense required) due to the inherent beamforming in 802.11ac.

    Not that I know anything about beamforming.

  • Hello everyone. Have a question about WiFi. I want to buy this WiFi card - "Compex WLE900VX Atheros QCA9880 minipci-e 802.11AC" with the future support 802.11ac standard. I think that sometime in the future support 802.11ac will appear in pfsense. If I put on ATH10K driver will it work normally in the range of 802.11n on pfsense 2.2?

  • Netgate Administrator

    ath10k is a Linux driver and will not work at all for pfSense which is built on FreeBSD.
    I don't believe there is any support for the QCA9880 chipset in FreeBSD currently.


Log in to reply