WLAN Radio Frequency Channels
WLAN operates in unlicensed radio frequency (RF) spectrum allocated by governing bodies in individual countries for signal transmissions. Appropriate regulatory bodies specify maximum allowable output power.
Refer to IEEE® Std 802.11™-2016, Annex E for detailed description of country information, operating classes, and behavior limits. The discussion here is restricted to identification of the WLAN operating frequency channel designations.
In general, the 2.4 GHz and 5 GHz bands of operation designate channels spaced 5 MHz apart, with noted exceptions. As an example, the 2.4 GHz band designates channels 1 through 13 spaced 5 MHz apart plus a 14th channel 12 MHz from channel 13. Defined WLAN channel bandwidths are greater than 5 MHz, therefore cross-channel interference limits the number of designated usable channels. Access point deployments manage interference from neighboring cells by operating on non-overlapping channels. In the United States, the 2.4 GHz band designated usable non-overlapping channels are 1, 6, and 11.
The channel center frequency, FCENTER, is calculated using the starting frequency, FSTART, and the channel number.
FCENTER in MHz = FSTART + (5×Channel Number)
Example: Determine the center frequency for channel number 6 in the 2.4 GHz band.
FCENTER in MHz = 2407 + (5×6) = 2437 MHz.
| 802.11 channels | ||
|---|---|---|
Channel Number | FSTART, Starting Frequency | Comments |
1, ..., 13 | 2407 MHz | For country- and release- specific restrictions, refer to [1] |
14 | 2414 MHz | |
132, 133, 134, 136, 137, 138 | 3000 MHz | |
131, ..., 138 | 3002.5 MHz | |
183, ..., 197 | 4000 MHz | |
182, ..., 189 | 4002.5 MHz | |
21, 25 | 4850 MHz | |
11, 13, 15, 17, 19 | 4890 MHz | |
1, ..., 10 | 4937.5 MHz | |
7, ..., 12, 16 34, ..., 60 in increments of 2 64 100, 104, 106, 108 112, 114, 116 120, 122, 124, 128 132, 136, 138 140, 144, 149 153, 155, 157 161, 165, 169 171, ..., 184 in increments of 1 | 5000 MHz | |
6, ..., 11 170, ..., 184 in increments of 1 | 5002.5 MHz | |
1, 2, 3, 4 | 56.16 GHz | |
References
[1] IEEE Std 802.11-2016 (Revision of IEEE Std 802.11-2012). “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 P802.11ax™/D4.1. “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amendment 1: Enhancements for High Efficiency WLAN.” Draft Standard for Information technology — Telecommunications and information exchange between systems. Local and metropolitan area networks — Specific requirements.