802.11

Protocols and notes handy for long distance comms:

Spec Band Bandwidth Notes
802.11 2.4GHz 22MHz Original WiFi band
802.11a 5GHz 20MHz Original 5GHz WiFi band
802.11b 2.4GHz 22MHz More bandwidth for 2.4 GHz
802.11g 2.4GHz 20MHz Brings 802.11a to 2.4 GHz
802.11n 5GHz, 2.4GHz 20MHz, 40MHz First multi bandwidth mode, MIMO modes not helpful for long distance comms
802.11ac 5GHz 20MHz, 40MHz, 80MHz, 160MHz More room for wider bandwidths, allowing for speeds up to 3.5 GBps. MIMO modes not helpful for long distance comms

Notes:

  • There are devices out there that have Unusual Bandwidths (below).
  • Some information from Wikipedia: 802.11

Bandwidth

Common bandwidths in the 802.11 Standard are: 20 MHz, 22 MHz & 40 MHz. 802.11ac also adds 80 MHz & 160 MHz.

Narrower bandwidths increase distance, half the bandwith has a gain of 3dB.

Distance increases the path loss decreases signal by the inverse square law, double the distance increases the loss by 6dB; a 3dB loss is sqrt(2) * d.

Some devices have Unusual Bandwidths:

Unusual Bandwidths

Known bandwidths and known equipment:

Bandwidth Equipment
5 MHz Ubiquiti airOS, TP-Link (PharOS)
10 MHz Ubiquiti airOS, TP-Link (PharOS)
20 MHz 802.11a, 802.11g, 802.11n, 802.11ac
22 MHz 802.11, 802.11b
40 MHz 802.11ac
80 MHz 802.11ac
160 MHz 802.11ac

Linux supports 5 MHz and 10 MHz bandwidths in the mac80211, ath5k & ath9k drivers.

List of devices known so far:

  • QCA9590, PCIe
  • AR9160 PCI/CB
  • AR5416 PCI/CB
  • AR9220 PCI/CB
  • AR5213 PCI/CB