1.What is the difference between WLAN and Wifi?
Wifi is a standard wifi based on the IEEE 802.11 protocol
WLAN has multiple protocols, such as IEEE802.11
The purpose of frequency band, channel and bandwidth
[Working frequency band] Divide the frequency into multiple segments, such as 2.4G (2401~2423Mhz)/5G (below 6Ghz)
[Wireless channel] Divides the frequency band into multiple channels, which are mainly used to transmit radio wave signals.
[Channel bandwidth] The greater the bandwidth (common 20/40/80/160), the greater the data transmission rate
2. Common standards of IEEE802.11
standard |
frequency band |
rate |
bandwidth |
802.11b |
2.4Ghz |
11Mbps |
20Mhz |
802.11g |
2.4Ghz |
54Mbps |
20Mhz |
802.11n |
2.4Ghz/5Ghz |
72Mbps(1x1) 150Mbps(1x1) 288Mbps(4x4) 600Mbps(4x4) |
20Mhz/40Mhz |
802.11a |
5Ghz |
54Mbps |
20Mhz |
802.11ac |
5Ghz |
433Mbps 867Mbps 6.77 Gbps |
40Mhz/80Mhz/160Mhz |
802.11ax |
2.4Ghz/5Ghz |
Maximum rate 9.6 Gbps |
40Mhz/80Mhz/160Mhz |
Starting from 802.11n, MIMO ( Multiple-Input Multiple-Output ) multi-antenna transmission and reception technology is used, which allows the server (RF router device) and the client (receiver device) to transmit data on multiple channels at the same time, thereby speeding up transmission. Efficiency, for example, 1x1 means that one antenna sends data and the client receives 4x4, 1x8 with one antenna, etc. The same is true, but it is more limited by client problems and cannot truly realize some "multiple transmissions and multiple receptions"
3. Introduction to 2.4GHZ/5Ghz frequency band
The range of the 2.4Ghz frequency band is (2401Mhz~2403Mhz)
The 2.4Ghz frequency band is divided into 14 channels (currently available in China are 1~13)
The channel bandwidth is only 20Mhz. Due to the isolation band, it is actually 22Mhz.
Adjacent channels will be separated by 5Mhz, and there are only 3 groups of channels that can achieve non-interference with each other.
Questions about the 5Ghz frequency band
5Ghz的频段主要在4.915Ghz~5.865Ghz
宽带数量也比2.4G多很多
4. 2.4Ghz和5Ghz wifi频段的区别是什么？
2.4Ghz优点：2.4Ghz频段的wifi 信号强，衰减较小，穿墙和覆盖范围更远
缺点：带宽窄，干扰强，速度慢
5Ghz 优点：带宽大，速度快，干扰较少
缺点： 信号弱，衰减较大，穿墙和覆盖范围都不及2.4Ghz频段
2.4Ghz的频率较低，所以穿透能力更强，反之，5Ghz的效果更差，有可能10米之内有一堵墙都可能导致只有一半效率