Methods of solving Wi-Fi wireless signal interference

Over the past decade, 802.11 technology has made great strides----faster, stronger and more scalable. But there is a problem in the troubled Wi-Fi: reliability.


for network administrators, the most frustrating for them is that users complain about the poor Wi-Fi performance, the coverage is not stable, often drop the line. Dealing with a Wi-Fi environment that you can't see and change frequently is a tricky problem. The culprit of this problem is radio frequency interference.


almost any device that emits electromagnetic signals generates radio frequency interference. These devices include cordless phones, Bluetooth devices, microwaves, and even smart meters. Most companies do not realize that one of the biggest sources of interference with Wi-Fi is their own Wi-Fi network.

Unlike the authorized radio spectrum, Wi-Fi is a shared medium that is
between 2.4GHz and 5GHz without the need for radio frequency authorization.


when a 802.11 client device hears other signals, whether or not it is a Wi-Fi signal, it will defer transmission until the signal disappears. Interference in transit can also cause packet loss, forcing Wi-Fi to retransmit. These retransmissions will slow the throughput rate, causing a significant delay for users sharing the same access point (AP).


Although some APs have integrated spectrum analysis tools to help IT staff see and recognize Wi-Fi interference, these initiatives are of little use if they do not really address the problem of interference.

The
new 802.11n standard makes the problem of radio interference worse. In order to be able to transfer multiple Wi-Fi streams simultaneously to achieve faster connectivity in different directions, 802.11n typically uses multiple launch devices on one AP.


Similarly, the error also turned twice times. If only one of these signals is disturbed, the performance of the two basic technologies of the 802.11n-space multiplexing or bound channel will decrease.


Common methods for solving disturbances


currently has three common methods to address radio interference, including reducing the physical data transmission rate, reducing the transmission power of the disturbed AP and adjusting the channel distribution of the AP. In certain cases, each of these three methods works well, but none of the three methods can fundamentally address the problem of radio interference.


Today, the majority of the AP is the omni-polar antenna used in the market. These antennas transmit and receive at a comparable rate in all directions. Since these antennas transmit and receive at the same speed in any case, the only option for these devices is to confront the disturbance when there is interference. They must reduce the physical data transfer rate until the packet loss rate reaches an acceptable level.


However, lowering the data transmission rate of AP can not achieve the expected results. Packet latency becomes longer, which means it takes more time to receive, so the chances of a switch are greater. This makes them more sensitive to periodic disturbances. This solution is largely ineffective, resulting in the impact of all users sharing this AP.


Another approach is to lower the AP transmission power to better use the limited channel. This requires reducing the number of devices that share the same AP, which can improve performance. But reducing the transmission power will also reduce the signal reception strength. This becomes a reduction in the rate of data transfer, while Wi-Fi coverage will appear vulnerable. These vulnerabilities need to be filled with more AP. It can be imagined that increasing the number of AP will cause more interference.


Please do not change the channel


Finally, most WLAN vendors will convince you that the best way to fix Wi-Fi interference is to "change the channel." But when radio interference increases, where is the "clean" channel available for AP automatic selection?


Although it is a useful technique to change the channel in response to persistent disturbances in a particular frequency, disturbances are often characterized by intermittent and variable variability. Due to the limited number of channels available for change, this technique can lead to more problems.


is the most widely used 2.4GHz band in Wi-Fi, with only three channels that are not interfering with each other. Even in the 5GHz band, after excluding the dynamic frequency selection, there are only 4 overlapping 40MHz-wide channels.





802.11 available channels in the 5GHz spectrum range


AP Changes the channel needs to connect the client disconnect, reconnect, which can cause audio and video applications to be interrupted. Changing the channel also creates a domino effect, as the adjacent AP also needs to change the channel to avoid interference with the channel.


When the device uses the same channel or radio frequency to transmit and receive Wi-Fi signals, the devices interfere with each other, which is called the same channel interference. To minimize interference with the channel, the network administrator makes the access points far enough apart to ensure that they cannot hear each other or interfere with each other. However, Wi-Fi signals are not limited to these networks, they will diverge.


changing the channel is not considered to be the most suitable method for the user. In these scenarios, the interference is determined by the AP that is in the dominant position. What did the customer see? Turning to a clean channel is really useful to users?


hope: stronger signals and less interference


the common unit for predicting the performance of Wi-Fi systems is signal-to-noise ratio (SNR). Snr shows the difference between the intensity of the received signal and the bottom noise. Usually in the case of high Snr, very little bit error, the throughput is also high. However, with the advent of interference, network administrators also need to consider the signal and interference and noise ratio (SINR).


Sinr is the difference between signal and interference. Due to the negative impact of radio interference on user throughput, SINR has become a useful indicator of the performance of Wi-Fi networks. High SINR means a higher data transmission rate and greater spectral performance.


in order to achieve high SINR value, the Wi-Fi system must increase signal gain or reduce interference. The problem is that the usual Wi-Fi system increases signal strength only by increasing power or by connecting high gain directional antennas. The latest Wi-Fi innovation in the field of Adaptive Antenna array allows the network administrator to gain gain and channel through directional antennas without increasing the number of AP.


uses smart antennas to reduce interference


Wi-Fi solution to interference is to have the Wi-Fi signal directly directed to a user and monitor the signal to ensure that the highest throughput transmission, while the regular redirect Wi-Fi transmission of the signal path, without changing the channel in the case of the use of clean signal path.


's new Wi-Fi technology combined with dynamic beamforming and miniaturized smart antenna formations has become the best solution.


dynamic beamforming based on antenna is a new technology which can change the shape and direction of RF energy from AP. Dynamic beamforming enables the regulation of Wi-Fi signals, which automatically "steer" them away from interference when interference occurs.


For each customer, these systems use different antennas, and they adjust the antenna when there is a problem. For example, when a disturbance occurs, the smart antenna chooses a decay signal pattern in the direction of interference to increase SINR and avoid reducing the physical data transfer rate.


Beamforming uses a large number of directional antennas to create thousands of antenna modes between the AP and the user. Because the RF energy can be transmitted with the best path, it can bring the highest data transmission speed and the lowest switch rate.


Standard Wi-Fi media access control (MAC) client receipts can monitor and determine the signal strength, throughput rate, and error packet rate of the selected path. This ensures that the AP can accurately know the user's experience, and if interference occurs, the AP can automatically adjust to find the best path. Smart antenna array also plays an active role in resisting interference.

　　Automatic anti-jamming for beam forming
Perhaps the greatest benefit of this new technology is that it eliminates manual or human involvement in operations.
For network administrators, reducing radio interference is becoming increasingly important as a large number of Wi-Fi devices enter the corporate network. At the same time, users are increasingly expecting high reliability Wi-Fi connections that can support streaming multimedia applications.
One of the key to solve the radio interference is to solve the problems in the development of enterprises. This also means adopting more intelligent adaptive methods to cope with the radio frequencies that drive control, because radio frequency control is the root cause of these problems.