Wi-fi is so fast, why watch video or card?  Here’s how to optimize your home Wi-Fi  

I believe that many friends in the selection of wireless router, will be confused by the wireless router below the mixed comments, there are always people will say: “this router signal is not good, often cut off flow”, there are also another part of the people said: “coverage is very wide, fast”.  Clearly is the same product why can produce such two levels of differentiation?  The author thinks there are two reasons. On the one hand, there are a lot of terms in wireless router that are difficult for ordinary users to understand, and ordinary consumers do not know what this option is.  On the other hand, the default Settings of today’s home wireless routers are not smart enough to degrade the network.  

To find out what each parameter in a wireless router is and how we can optimize the wireless network, see below.  

Polarizing reviews of the same product  

Wi-fi signal in the end how can be considered excellent?  

Wireless signal is actually a very complicated issue. Due to the lack of good popular science and misleading marketing by manufacturers, many consumers simply believe that a higher measurement speed represents a better Wi-Fi signal strength.  

In this article we’ve looked at the problem of ideal Wi-Fi speeds.  However, higher Wi-Fi transmission speed can only represent one aspect, and does not mean that the Wi-Fi signal is optimized.  “Sudden increase in game latency” (loss of wi-fi packets) and “frequent buffering while watching videos” (loss of Wi-Fi streaming) all indicate that the Wi-Fi is not good.  If you’re a Mac, hold down Option and click on the Wi-Fi icon to see the following parameters:  

A set of Wi-Fi parameters  

To optimize the Wi-Fi signal, we need to optimize the channel, bandwidth, signal strength (RSSI), noise and SNR.  

The above parameter is a good Wi-Fi signal:  

Channel: 149  

Bandwidth: 40 MHz  

Signal strength: -30 dBm  

Noise: -93 dBm  

SNR: 63 dB  

Channel and bandwidth  

In the last article, we talked about the relationship between bandwidth and speed. You can simply think of bandwidth as the number of lanes on a highway. The more lanes there are, the more traffic can be driven per unit of time.  

And the Wi-Fi that you’re using has a place in all the bands, and that’s the channel, and the channel is the segmentation of the band.  There are a total of 13 channels assigned to 2.4ghz channels in China, and they are marked 1-13 successively, with a difference of 5Mhz between each channel. It can be seen from the following figure that the adjacent frequency bands overlap with each other, that is, interference will occur between each other.  Therefore, up to three non-interfering 20Mhz or one 40Mhz Wi-Fi signal can be accommodated at 2.4GHz.  

Distribution and overlap of 2.4GHz channels  

For 5GHz Wi-Fi, the available channels are 36-64 in 5.2ghz and 149-161 in 5.8ghz.  The diagram below:  

Distribution and overlap of channels at 5GHz  

It is important to note that UNI-2-Extended is not available domestically, so it can accommodate up to three non-interfering 80Mhz signals or one 160Mhz band signal at 5GHz.  The signal can adjust its channel number to reduce overlap and avoid interference, with a single channel in 2.4GHz and four channels in 5GHz.  

noise  

Noise is an important indicator that affects wi-fi signals. Noise can come from other wi-fi signals in the neighborhood, as well as other radio signals in the same band, such as Bluetooth and Zigbee signals at 2.4GHz.  Even RF leaks from microwave ovens and fluorescent lights can affect Wi-Fi signals in the 2.4GHz band.  If noise levels are too high, the strength and performance of wireless signal strength may be reduced.  Noise, like signal strength, is also used in dBm. Generally, noise below -90dbm does not interfere with normal Wi-Fi use.  

Signal to noise ratio  

Signal-to-noise ratio (SNR) is the power ratio between signal intensity and noise level.  The unit of SNR is dB, which is an absolute value, and the calculation method is as follows:  

SNR (dB) = RSSI (dBm) – Noise (dBm)  

Generally speaking, the SNR above 30dB is a good environment, and the wireless Internet experience will be seriously affected when the SNR is below 30dB.  The noise of general home wireless network is about -90 – -95 dBm, and the high quality signal needs to be above -65 dBm.  

Although many home wireless routers have the function of “automatic channel optimization”, the actual effect is not good after the author’s experience. The wireless router cannot choose a channel with minimum noise and interference. Some wireless routers that support 160MHz will not reduce the bandwidth because of excessive environmental noise.  Next, let’s talk about how to manually optimize wi-fi using a practical example from my bedroom.  

Firstly, I need to find a wi-fi analysis software with relatively complete functions. The author uses Wi-Fi Explorer on Mac, which is included in Setapp.  If you have an Android mobile device, you can also use UBNT’s Wifiman.  Windows users can consider using inSSIDer to analyze Wi-Fi:  

Wi-Fi Explorer  

Once inside, you’ll see a screen that details all the Wi-Fi signals that the Mac can currently receive from different aps.  Detailed information about the selected network, such as signal strength, channel, bandwidth, and SNR, is displayed at the bottom of the screen.  

Click on the “Spectrum 2.4/5 GHz” TAB at the bottom of the page to see the full channel usage in the current environment.  

Take 5GHz as an example: as mentioned above, the 5.2ghz band can accommodate two full 80Mhz bands or one full 160Mhz band, while the 5.8ghz band can only accommodate one full 80Mhz band.  However, many high-end routers come out of the factory with a default bandwidth of 160MHz, so we can set the AP to 160MHz to observe the wireless environment carefully:  

Although the negotiated rate is up to 4.8Gbps at this time, the 5GHz Wi-Fi to noise ratio is up to 48%, even in the vicinity of AP, SNR is only 46 dB.  The lower signal-to-noise ratio means that the amount of effective data transmitted at each time is also less, reflecting the actual use situation, such as the use of AirPlay and other wireless transmission protocols, is often interrupted and other phenomena, the experience is very poor.  

Due to the complex wireless environment of dormitory buildings, each room has at least one wireless router and a large number of AP arranged by the school, the author will be interfered even when the bandwidth is set at 80Mhz, so we can only settle for the next channel with the bandwidth of 40mhz 149 channel.  At this time, the noise ratio is only 3%, and the SNR is increased to 61 dB. At this time, the handshake bandwidth is still 600Mbps, which can fully meet the vast majority of wireless network scenarios.  

Therefore, we can completely sacrifice the negotiation speed of Wi-Fi to obtain a more stable Wi-Fi experience, and after optimization, AirPlay and other protocols based on local area networks also get a great improvement in the experience.  

Of course, the environment I live in is a very complex network environment, you in their own optimization of the time to cut not according to the picture, but also need to combine with their own actual situation.  In general:  

Normal family environment 5Ghz bandwidth using 80 MHz channel selection generally no problem.  The 160 MHz will interfere with any wi-fi at 5.2GHz, so it’s not recommended in less-pristine environments.  

If you are like the author in a dormitory or rented house with a complex wireless environment, it is recommended to choose 40MHz/80MHz for higher connection stability.  At 5GHz, if 80 MHz is selected, 36,64,149,165 channels are recommended; if 40MHz is selected, more channels are recommended.  

For 2.4ghz networks, it is recommended to use the minimum 20Mhz band, as well as 1,6, 11/13 channels.  However, even this optimized experience may not be very good. There are so many things that interfere with 2.4g Wi-Fi that the author does not recommend using 2.4ghz as a home backbone network in the current wireless environment.  

How should multiple wireless routers be set up  

2.4ghz interferes so much that all major mobile devices now support 5GHz Wi-Fi for high-speed wireless Internet connections.  But the 5GHz range is much smaller than the 2.4ghz range, and most homes have weak boxes just inside the door, so there will inevitably be 5GHz Wi-Fi dead spots in your home.  

Therefore, in order to provide a good wireless environment in the home, multiple APS are needed to improve the signal coverage of the main activity area in the case of larger houses, more load-bearing walls or signal dead angles that need to be improved.  However, optimizing the wireless environment for a multi-AP environment is a more complex task.  

Channel regulation  

When you have multiple aps, the signal strength diagram is shown in the figure above, but do not be fooled. Wireless signals sent by each AP are independent and interfere with each other regardless of Mesh or AC+AP mode.  

So not only is the middle intersection region not the strongest signal, but on the contrary, it is the region with the most severe interference.  The wireless signal from your other AP, like your neighbor’s wireless signal, can interfere with the device you’re currently surfing the Internet on.  

It can be seen that the use of 160MHz channel interference is serious  

Although BSS Coloring is introduced by Wi-Fi 6, there is not enough evidence to show that it has any significant effect gain in the actual environment.  So the most direct optimization we can do is to stagger the frequency bands between different aps or make the signals generated by aps not interfere with each other.  

For a simple example: if you choose a 40/80mhz bandwidth, you can assign three separate 80MHz bands at 5GHz, or six separate 40MHz bands to different aps.  

If 160MHz is selected, since 160MHz can only be used in 5.2ghz, the signals of multiple aps will definitely interfere with each other, but we can optimize it by using the method mentioned in “roaming and Power Regulation” below.  

Choosing low frequency signals gives you more freedom and less interference, while 160MHz gives you higher connection speeds but is also more sensitive to signal strength and interference.  Therefore, for ordinary households, the author suggests that 80MHz or a medium speed and relatively free channel selection space should be selected as far as possible under the condition that there is no high-speed mobile demand.  

In addition, there are some things to be aware of:  

52-64 channels, also known as DFS channels, can also be occupied by commercial/military high power equipment, which may cause some interference if you have similar equipment near your home.  

5.8ghz is relatively “clean”, but the coverage is slightly reduced compared to 5.2ghz.  

Of course, the above channel optimization is limited to AP that supports free channel selection. In the home wireless router used by the author, Linksys supports free adjustment of all channels, while Xiaomi blocks all channels except 36-48 channels after the Mesh network is formed.  In addition, all the home wireless routers used by the author do not support meticulous adjustment of child nodes after Mesh networking. Friends who want to do meticulous adjustment of child nodes may need to buy AP.  

Power regulation  

If channel adjustment is not supported, how can we eliminate the signal interference between aps? The answer is also very simple: we only need to make the signal of one AP in our common area can be received, so as to ensure that there is no interference from another AP in this position, and thus have a good Internet experience.  

To do this we can:  

Optimize placement between aps.  

Optimized AP transmission power.  

Placement position is not difficult to understand, wireless signals through the air and various obstacles will produce different attenuation, through a reasonable placement of AP position, can make the common activity area of the signal does not fight.  

When the location selection is limited, or the wireless Mesh has to be placed near the main AP signal, we can appropriately lower the AP transmitting power:  For example, in the setting of xiaomi router, we can change from “through the wall” to “save energy” to reduce the transmitting power of AP, so that the strong signal can only be kept in the room where it should be.  This adjustment not only optimizes Internet access experience, but also improves roaming efficiency between aps.  

Roaming Settings  

When your mobile device moves between two aps, the terminal will quickly switch between multiple aps according to the strength of the signal, so that the terminal always has a good Internet access experience, this is roaming.  Roaming takes a certain amount of time to switch connected aps. If no seamless roaming is performed, you need to manually disconnect an AP to connect to the next AP.  Generally speaking, the main means of roaming is through 802.11K/V/R protocol.  

The main function of 802.11k protocol is Radio Resource Measurment.  Simply put, 802.11k can provide roaming AP information to terminals (mobile phones, etc.) if the current AP model is weak.  

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