The 2.4 GHz band has 11 22-MHz-wide channels defined, starting at 2.412 GHz every 5 MHz through 2.463 GHz. Three non-overlapping channels are available: 1, 6 and 11, as shown in Figure rf-1. These non-overlapping channels can be used in a three-to-one reuse pattern, as shown in Figure rf-2.
Three-to-one reuse pattern
The operating channel center frequencies are defined at every integral multiple of 5 MHz above 5 GHz. The valid operating channel numbers are 36, 40, 44, 48, 52, 56, 60, 64, 149, 153, 157, and 161. The lower and middle U-NII sub-bands accommodate eight channels in a total bandwidth of 200 MHz. The upper U-Nii band accommodates four channels in a 100 MHz bandwidth. The centers of the outermost channels are 30 MHz from the bands' edges for the lower and middle U-NII bands, and 20 MHz for the upper U-NII band (see Figure rf-3).
5 GHz Channels
Point-to-point links operates on the other four channels: 149, 153, 157, and 161. This allows four channels to be used in the same area. 802.11a APs and client adapter cards operates on eight channels: 36, 40, 44, 48, 52, 56, 60, and 64. This allows two four-to-one reuse patterns to be used (see Figure rf-4).
Four-to-one reuse pattern
Using both the low- and mid-frequency ranges together allows a seven-to-one reuse pattern with a spare. The spare can be added for a fill to extend coverage or to add capacity in areas like conference rooms where more capacity is needed (see Figure rf-5).
Seven-to-one reuse pattern with a spare