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WLAN Radio Frequency Channels

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This example describes WLAN radio frequency channel designations and shows how to calculate the channel center frequency in accordance with IEEE® 802.11™ specifications.

IEEE 802.11 Channel Designations

WLAN operates in unlicensed radio frequency (RF) spectra. Governing bodies in individual countries allocate these spectra and appropriate regulatory bodies specify values of maximum allowable output power. For a detailed description of country-specific information, operating classes, and behavior limits, see Annex E of [1] and [2].

The IEEE 802.11 standards designate bands for signal transmission, each corresponding to a standard or group of standards. Of these, WLAN Toolbox™ software supports these bands and corresponding standards.

  • 900 MHz (802.11ah™)

  • 2.4 GHz (802.11b/g/n/ax/be)

  • 5 GHz (802.11a/h/j/n/ac/ax/be)

  • 6 GHz (802.11ax/be)

  • 60 GHz (802.11ad/ay)

Within each band, the standards specify channel numbers with a designated channel spacing. For example, the 2.4 GHz band contains channels 1 to 13, spaced 5 MHz apart, and channel 14, spaced 12 MHz from channel 13. Each band also has a designated channel start frequency, fs, for the first channel. For the 2.4, 5, and 6 GHz operating bands, fs is 2.407, 5, and 5.950 GHz, respectively.

Because WLAN channel bandwidths are greater than 5 MHz, cross-channel interference limits the number of designated usable channels. Access point deployments manage interference from neighboring cells by operating on nonoverlapping channels. In the United States, the 2.4 GHz band designated usable nonoverlapping channels are 1, 6, and 11. This figure shows overlap for channels 1–14 in the 2.4 GHz band.

Channels 1-14 overlapping in the 2.4 GHz band

Channel Center Frequency Calculation

To determine the channel center frequency for a given channel number in the 2.4, 5, or 6 GHz frequency band, use the wlanChannelFrequency function. For example, calculate the center frequency of channel 6 in the 2.4 GHz band.

channel = 6;
band = 2.4;
fc = wlanChannelFrequency(channel,band)
fc = 
2.4370e+09

Calculate the center frequency of channels 37, 42, and 91 in the 6 GHz band.

channel = [37 42 91];
band = 6;
fc = wlanChannelFrequency(channel,band)
fc = 1×3
109 ×

    6.1350    6.1600    6.4050

References

[1] IEEE Std 802.11™-2020 (Revision of IEEE Std 802.11-2016). “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.” IEEE Standard for Information Technology — Telecommunications and Information Exchange between Systems — Local and Metropolitan Area Networks — Specific Requirements.

[2] IEEE® Std 802.11ax™-2021 (Amendment to IEEE Std 802.11-2020). “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amendment 1: Enhancements for High Efficiency WLAN.” IEEE Standard for Information Technology — Telecommunications and Information Exchange between Systems. Local and Metropolitan Area Networks — Specific Requirements.