This channel was opened up in March 2014 for use by Wi-Fi in the United States as part of the 802.11ac specification. Table 3: 80 MHz channels on the 5 GHz band. Lower (or Lower-Lower) Extension (primary is highest channel) Lower-Upper Extension (primary is 2nd highest channel) Upper-Lower Extension (primary is 2nd lowest channel) Upper (or Upper-Upper) Extension (primary is lowest channel) Table 2: 40 MHz channels on the 5 GHz band. Lower Extension (primary is highest channel) Upper Extension (primary is lowest channel) These are shown for 40 MHz channels in Table 2 and 80 MHz channels in Table 3. The three basic methods are to refer to their bonded channel range, their primary channel with extension for which there are two variants for 40 MHz and four variants for 80 MHz, or their center channels, or frequencies.
Unfortunately, there are multiple “standards”-ways of indicating bonded 5 GHz channels- which makes referencing those channels very confusing for Wi-Fi novices and experts alike. The other bonded channels are “extension” channels and can be either immediately above (upper) or below (lower) the primary channel. Each bonded channel has a primary 20 MHz channel that is used when an 802.11n or 802.11ac access point communicates with a legacy 802.11a client or an 802.11n or 802.11ac client that is artificially limited to smaller channels. Table 1: 20 MHz channels on the 5 GHz band.Ĭreating 40 MHz, and larger channels involve bonding multiple neighboring channels together. Most access points require that a country be selected in the configuration, which dictates what channels and maximum transmit powers are available. Governmental regulatory agencies in other countries may restrict the use of one or more of these frequency bands and the maximum transmit power at those frequencies.
#Transmit band full
The full list of 20 MHz channels available in North America is shown in Table 1. This is the primary advantage of deploying 802.11ac access points vs. In instances where a design calls for high client density settings like in convention meeting spaces or large classrooms, or if there is a specific reason to avoid the DFS channels, we can use 80 MHz channels with 802.11ac, and double the wireless throughput. In most SMB deployments, we can use 80 MHz channels with 802.11ac, to double the wireless throughput. The use of 40 MHz channels at 5 GHz with 802.11n is fairly standard practice. This is shown in Figure 3.įigure 3: Channels on the 5 GHz frequency band. 802.11n allows the use of 40 MHz channels, and 802.11ac allows the use of up to 80 MHz or 160 MHz channels. 802.11a allowed the use of 20 MHz channels. The 5 GHz band is much larger (over 555 MHz, semi-contiguous), so selecting independent channels and using larger widths via bonding neighboring channels is much simpler.
On the 2.4 GHz band, only 20 MHz channel sizes should be used, and channels should be deployed across APs with an alternating static 1, 6, 11 scheme, both horizontally and vertically. Given the restrictions on the number of independent channels and how that decreases as the channel width increases, poor channelization will create AP-to-AP interference and thus degrade both usage and coverage requirements. This limitation makes the use of 40 MHz channels completely impractical in multi-AP deployments, though it is still unfortunately fairly common to see in practice as most vendors allow this channel width in their default settings.įigure 2: 40 MHz channels on the 2.4 GHz frequency band. However, given that the entire usable band in 2.4 GHz is only 72 MHz wide, there are no two 40 MHz channel sizes that are independent, as shown in Figure 2. The 802.11n spec allows for the optional use of 40 MHz channels on the 2.4 GHz band, by bonding two adjacent channels together. Unfortunately, the center frequencies of channels 1-13 are only 5 MHz apart, leading to only three non-overlapping channels, as shown in Figure 1.įigure 1: 20 MHz channels on the 2.4 GHz frequency band. Some or all of channels 12-14 are allowed in some other countries, such as Japan. On the 2.4 GHz band (802.11b/g/n) in North America, there are 11 channels of 20 MHz size allowed by the FCC.
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