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RF Basic Background: 2.4G and 5G Band
03/26/2020 
24 
12461
DESCRIPTION:
RF Basic Background: 2.4G and 5G Band
RESOLUTION:
There are currently five widely adopted standards for 802.11 wireless network. There are 802.11a, 802.11b, 802.11 g, 802.11n, and 802.11ac. 802.11ac is the newest and highest capacity standards, while older client devices may not be able to utilize the newer standards. Following table lists the main characters for these five wireless standards.
| 802.11(X) | 802.11a | 802.11b | 802.11g | 802.11n | 802.11ac |
| Standard Approved | 1999 | 1999 | 2003 | 2009 | 2013 |
| Frequency Band | 5 GHz | 2.4 GHz | 2.4 GHz | 2.4/5 GHz | 5 GHz |
| Channel Width | 20 MHz | 20 MHz | 20 MHz | 20/40 MHz | 20/40/80/160 MHz (160M is optional) |
| Non-Overlapping Channels | 24 | 3 | 3 | 3/24 | 24 |
| MIMO/SISO | SISO | SISO | SISO | 4x4 MIMO | 8x8 MIMO |
| Data Rate | 54Mbps | 11Mbps | 54Mbps | 600Mbps (3x3, 40MHz) | 1.3Gbps (3x3, 80MHz) |
| Compatibility | 802.11a | 802.11b | 802.11b/g | 802.11a/b/g/n | 802.11a/b/g/n/ac |
- 2.4G Band Channels
- 5G Band Channels
- 2.4G vs 5G (Pro's and Con's)
- ?RF interference??
- Radio frequency barriers
2.4GHz Band Channels
In 802.11b/g/n 2.4Ghz radio band, there are 11 22MHz wide separate channels but only three channels (1, 6, and 11) are non-overlapping . APs and STAs operating in one of these three channels don't interfere with APs and STAs running in the other two channels.
| # | Channel | Frequency (GHz) | Location | Comments |
| 1 | 1 | 2.412 | North America | North America: C#1-#11 Europe: C#1-#13 Japan: C#1-#14 (802.11bg: #14 only) |
|---|---|---|---|---|
| 2 | 2 | 2.417 | North America | |
| 3 | 3 | 2.422 | North America | |
| 4 | 4 | 2.427 | North America | |
| 5 | 5 | 2.432 | North America | |
| 6 | 6 | 2.437 | North America | |
| 7 | 7 | 2.442 | North America | |
| 8 | 8 | 2.447 | North America | |
| 9 | 9 | 2.452 | North America | |
| 10 | 10 | 2.457 | North America | |
| 11 | 11 | 2.462 | North America |
2.4G Band Channel List
Five possible combinations of non-overlapping channels for 2.4G band. The red color set in the below picture is recommended. Therefore, to deploy more APs, you are required to try hard to utilize channel 1, 6, and 11. Howerver, for 802.11n 2.4G? when using 40MHz channel width, only one AP can be deployed. Hence, 40 MHz operation in the 2.4 GHz band should be avoided.
2.4G Channel map
5GHz Band Channels
In 802.11a/n/ac 5Ghz radio band, there are 24 20MHz wide separate channels and 23 channels are non-overlapping in North America. APs and STAs operating in one of these channels don't interfere with APs and STAs running in the other channels. However, due to possible interference with radar systems, only the top four (Indoor Only) and buttom five (North America) channels are commonly used. For the rest 15 channels, the Dynamic Frequency Selection (DFS) is must applied.
DFS monitors the region frequency of the radar signals. If radar signal is detect on the channel which AP is using, DFS will block the transmission on the channel and randomly switch to another channel to avoid the interference with the region radar system.
| # | Channel | Frequency (GHz) | Location | Comments |
| 1 | 36 | 5.180 | Indoor Only | North America:C#1-#24 Europe: C#1-19 Japan: C#1-#19 |
|---|---|---|---|---|
| 2 | 40 | 5.200 | Indoor Only | |
| 3 | 44 | 5.220 | Indoor Only | |
| 4 | 48 | 5.240 | Indoor Only | |
| 5 | 52 | 5.260 | DFS Required | |
| 6 | 56 | 5.280 | DFS Required | |
| 7 | 60 | 5.300 | DFS Required | |
| 8 | 64 | 5.320 | DFS Required | |
| 9 | 100 | 5.500 | DFS Required | |
| 10 | 104 | 5.520 | DFS Required | |
| 11 | 108 | 5.540 | DFS Required | |
| 12 | 112 | 5.560 | DFS Required | |
| 13 | 116 | 5.580 | DFS Required | |
| 14 | 120 | 5.600 | DFS Required | |
| 15 | 124 | 5.620 | DFS Required | |
| 16 | 128 | 5.640 | DFS Required | |
| 17 | 132 | 5.660 | DFS Required | |
| 18 | 136 | 5.680 | DFS Required | |
| 19 | 140 | 5.700 | DFS Required | |
| 20 | 149 | 5.745 | North America | |
| 21 | 153 | 5.765 | North America | |
| 22 | 157 | 5.785 | North America | |
| 23 | 161 | 5.805 | North America | |
| 24 | 165 | 5.825 | North America |
5G Band Channel List
5G Channel map
In 5 GHz band, higher data rates (wider channel width) means fewer available channels. With 802.11a, there are a total of 24 non-overlapping channels available, but with 802.11ac, achieving the maximum data rate will reduce the number of non-overlapping channels to two for 80MHz and only one for 160 MHz wide (including DFS).
| Including DFS | Excluding DFS | |||
|---|---|---|---|---|
| Channel Size | North America | Europe | North America | Europe |
| 40MHz | 8 | |||
