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Wi-Fi Channels

Introduction

Common frequency bands : 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, and 5.9 GHz

WiFi channels

All Wi-Fi versions through 802.11n (a, b, g, n) work between the channel frequencies of 2400 and 2500 MHz. These 100 MHz in between are split in 14 channels 20 MHz each. As a result, each 2.4GHz channel overlaps with two to four other channels (see diagram above). Overlapping makes wireless network throughput quite poor.

Common channels for 2.4 GHz : 1, 6 and 11 (to avoid overlapping)

  • 2.4 GHz : This band provides coverage at a longer range but transmits data at slower speeds.
  • 5 GHz : On the other hand, the 5 GHz band provides less coverage but transmits data at faster speeds.

Compability

  • 802.11n : Set of LAN protocols that can be used in the 2.4 GHz or 5 GHz frequency bands.
  • 802.11ac : Extended channel binding from 40 MHz in 802.11n to optional 160 MHz and mandatory 80 MHz channel bandwidth for stations.
  • 802.11ax : All band spectrums between 1 and 7 GHz.

List frequencies and channels

$ ip a
...
4: wlp0s20f3: <BROADCAST,MULTICAST,UP,LOWER_UP>...
...
$ sudo iwlist wlp0s20f3 scan | grep Frequency | sort | uniq -c | sort -n
      1                     Frequency:5.745 GHz
      2                     Frequency:2.412 GHz (Channel 1)
      3                     Frequency:5.18 GHz (Channel 36)
      3                     Frequency:5.5 GHz (Channel 100)
      3                     Frequency:5.66 GHz (Channel 132)

References