Detailed Explanation of WiFi Wireless Network Technology

Introduction to Wireless Networks

Wi-Fi is a technology that allows electronic devices to connect to a wireless local area network (WLAN), usually using the 2.4G UHF or 5G SHF ISM radio frequency bands. Connections to wireless LANs are usually password protected; but they can also be open, allowing any device within range of the WLAN to connect.

Now the main frequencies of WIFI networks are 2.4GHz and 5GHz, and the speeds are divided into ABGN AC;

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2.4G and 5G

Frequency 2.4GHz and 5GHz

2.4G

The advantage is that the frequency band has strong anti-attenuation ability in indoor environment and good wall penetration ability.

The disadvantage is that many devices use 2.4GHz, such as Bluetooth and Zigbee wireless, so there is a lot of interference and sufficient stability cannot be guaranteed.

5G

The advantages are strong anti-interference ability, ability to provide larger bandwidth, high throughput and strong scalability.

The disadvantage is that 5G is only suitable for small-scale indoor coverage and outdoor bridges, and the attenuation effect caused by various obstacles is much greater than that of 2.4G.

The difference between abgn and ac

1)2.4G:

802.11b 11M

802.11g 54M

802.11n 600M

2) 5G:

802.11a 54M

802.11n 600M

802.11ac 600*3M

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1) The wireless AP automatically obtains IP and AC addresses through DHCP;

2)AP registers to AC;

3) Centralized forwarding: A control layer is established between the AC and the AP, and data is forwarded through the Layer 2 tunnel established between the AC and the AP;

4) Local forwarding: A control layer is established between the AC and the AP, and data is forwarded through the AP's Layer 3 routing;

Wireless AP automatically obtains address and AC address

AP registers to AC

1) Local forwarding gif

2) Centrally forward GIF

AP deployment location

Method 1: AP comes with antenna coverage

AP is directly deployed in the corridor, and covers the area with its own antenna.

In this mode, due to the location of the AP antenna, some dormitories need the signal to penetrate multiple walls before they can be covered. Therefore, it is very likely to cause weak signals or even blind spots. Therefore, it is not recommended to use it in actual deployment.

Method 2: AP coverage through omnidirectional antenna

In this mode, APs and antennas are deployed in the corridor. Attention should be paid to the installation position of the omnidirectional antenna, so that the wireless signal can cover the user area through a partition wall as much as possible. However, if there are many dormitories on a floor and more than 4 APs are needed for coverage, co-channel interference will inevitably occur between APs on the same channel. Therefore, this coverage method can be considered when there are less than 4 APs on a floor.

Method 3: Omnidirectional antenna deployment for indoor coverage

In this way, omnidirectional antennas are deployed in the student dormitory, and each antenna covers three surrounding dormitories. The advantage of this method is that it increases the attenuation of wireless signals through partitions to avoid mutual influence between APs on the same channel. However, this method deploys antennas indoors, which is inconvenient for construction and operation and maintenance.

summary:

If the number of APs on the same floor is greater than 4, method 3 is recommended. Otherwise, method 2 is recommended. If the walls and floors have little effect on signal attenuation in the actual environment, method 3 is recommended.

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