Channel selection of wireless WI-FI Router

"Many people have never paid attention to the Wi-Fi channels of routers. They think that as long as their laptops can be connected, there will be no problem with wireless routing. However, there is a problem that many mobile devices cannot support full channels, including power consumption and target countries. Therefore, when conditions are met, it is best to check the signal-to-noise ratio and select a channel that best suits you, instead of letting the router choose its own channel when it starts ."

Http://zoomquiet.org/res/scrapbook/ZqFLOSS/data/20110526160026/

But then another friend said, "popularity ...". Refer to Avinash Kaushik's "Occam's" blog on his website.
Razor "the feeling at the fifth anniversary of its founding (this article is worth reading, very
Inspiring), I think even if I am not an expert, it would be nice to share what I know.

Now many families have their own wireless Wi-Fi routers and mobile devices connected to the Internet: laptops, netbooks, mobile phones, tablets, e-paper books, and mid (down ). Many mobile devices may encounter strange problems when connecting to the Internet. This article only focuses on one of the strange problems: Wrong channel (also translated as channel and frequency band) configuration, leading to failure to connect to the Internet or poor signal.

I will not explain the exact technical knowledge. If you are interested, you can read Wikipedia Wi-Fi or IEEE.
802.11. The following describes why to configure a wireless channel and how to select a wireless channel.

Why do I need to configure a wireless channel?

I believe everyone has used the radio. When you use a radio, there is a problem with selecting a TV set. Whether you use a knob, a button, or a touch, you must select a TV set to listen to the TV set. The same is true for wireless routing. The wireless router in your home will broadcast an SSID (the name of the wireless connection you see). Clicking this connection will make your computer modulated to the channel where the connection is located for communication.

However, when using the radio, the following problems may occur: 1. some computers cannot receive it at all. For example, your radio is not in the full band. 2. some of them are too noisy to hear, such as some haona radio stations. Similarly, in your wireless environment, question 1 is transformed into "A laptop (full-band radio) can connect to a wireless router, but a tablet (non-full-band radio) cannot connect "; problem 2 is converted to "can connect to a wireless router, but there is too much interference to reach the maximum speed (this speed refers
Wi-Fi connection speed, independent of ADSL Network speed )".

If it is not manually configured, the wireless router automatically selects a default or random channel for broadcast and connection establishment. This is OK when the device is not connected to the Internet and is used by others.

However, if all people around you have wireless devices and most people use wireless routers (or wireless cats) from the same carrier, it is very likely that everyone chooses the same channel for communication. This will cause a lot of signal interference, which generally does not affect the network speed-unless your home ADSL is greater than 4 m, but it will lead to extremely slow data transmission between the two home devices, for example, when a wireless video file is sent to a mobile phone using a pea pod.

If your wireless router randomly chooses a channel, it is very likely to select a channel not supported by your device. I once met a patriot model mid that only supports channel 1-9, but the wireless router chooses Channel 11. It cannot be connected! It is normal that mobile devices do not support certain channels to reduce power consumption or other considerations. In addition, different countries have different radio channel control conditions (see list
Of WLAN channels), water equipment from other countries may not be satisfied when they arrive in China.

Fortunately, you cannot control the radio band, but you can control the wireless channel of your own wireless router. For details about how to modify the wireless channel, refer to the help documents of vro manufacturers or seek help online. However, before the modification, you still faced the problem: Which channel should I change?

How do I select a wireless channel?

First, select the channel that your communication device supports. Before that, make sure that all devices support the same protocol. For example, if your mobile terminal does not support IEEE 802.11n, you have to use the 802.11n protocol on the vro. For this knowledge, refer to the device manual or try it yourself. In Linux, you can use iwlist channel to list all the channels supported by mobile terminals. For example, the channel supported by Kindle is (I am sure the problem with Kindle is not due to the channel, unless he uses a Japanese router ):

[root@kindle root]# iwlist channello        no frequency information.wlan0     13 channels in total; available frequencies :          Channel 01 : 2.412 GHz          Channel 02 : 2.417 GHz          Channel 03 : 2.422 GHz          Channel 04 : 2.427 GHz          Channel 05 : 2.432 GHz          Channel 06 : 2.437 GHz          Channel 07 : 2.442 GHz          Channel 08 : 2.447 GHz          Channel 09 : 2.452 GHz          Channel 10 : 2.457 GHz          Channel 11 : 2.462 GHz          Channel 12 : 2.467 GHz          Channel 13 : 2.472 GHz          Current Frequency:2.412 GHz (Channel 1)

Second, select a channel with less interference when the interference cannot be tolerated. This can be done by scanning which channels are used by the SSID with relatively high signal strength. By comparing the channels with the channel list, you can select a channel that may have less interference. Specialized knowledge and tools (for example, iwconfig in Linux) are required for the test of HTTP and SNR, which may be laborious for ordinary people.

[root@kindle root]# iwconfig      lo        no wireless extensions.wlan0     AR6000 802.11g  ESSID:"mosaic"            Mode:Managed  Frequency:2.412 GHz  Access Point: 00:23:EB:B7:E6:94             Bit Rate=54 Mb/s   Tx-Power=16 dBm   Sensitivity=0/3            Retry:on             Encryption key:off          Power Management:off          Link Quality:49/94  Signal level:-46 dBm  Noise level:-96 dBm          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Finally, with the development of mobile terminals, more and more mobile terminals support more comprehensive channels, but there are always some terminal manufacturers abnormal. Therefore, this article only serves as a reminder and serves as a reference for solving wireless connection problems.