Analysis of unstable factors of wireless network

Is the wireless network unstable? Is there no problem with the hardware? What is the cause of the unstable wireless signal? Well, this requires a detailed analysis of all aspects of the wireless signal. So, let us study the reasons that affect the instability of wireless signals.

1. Interference with wireless signals

Because the wireless radio frequency of the wireless LAN uses the ISM (industrial, scientific, medical) wireless frequency band, where the 802.11b? 802.119 standard uses the 2.4G frequency band, and the 802.11a standard uses the 5.8G frequency band? Some of the sudden radio frequency interference of wireless devices in the same frequency band is affected in the operating environment? Such as microwave ovens? Bluetooth mobile phone signals are in the 2.4G frequency band?

So when working in a wireless LAN, a microwave oven is suddenly turned on in its area, or a Bluetooth mobile phone uses a Bluetooth Headset, or suddenly other wireless devices operating in the same frequency band interfere with the wireless signal of the wireless LAN? The physical environment of the wireless network occurs Changes, such as the sudden movement of large obstacles between the wireless AP and the wireless client, will directly cause a sudden and significant decrease in the network performance of the wireless LAN, and directly lead to a wireless signal interruption or rate reduction?

Another interference comes from the wireless LAN itself, that is, interference from different channels in the same frequency band? This interesting situation occurs in home users, which can only be mutual interference of wireless APs on adjacent or close buildings on the same floor? Neighboring wireless AP devices should use different interference-free channels? For example: 802.11b? 802.11g can use five-band channels to eliminate interference. Typical interference-free channels are set to 1? 6? 11, respectively. channel?

2. Wireless signal coverage and penetration

In the home environment, the distances are relatively short, and general wireless LAN devices claim to have a transmission distance of more than 100 meters, so the signal transmission distance is not a problem? But the family environment brings a new problem, that is, the family space is more Crowded, the space is not open enough, and the walls in the room are the main obstacles? Because the wireless LAN uses a wireless microwave frequency band? The biggest feature of microwave is that it spreads almost straight, and the diffraction ability is very weak, so it is behind the obstacles Will my wireless receiving device receive a very weak signal, or no signal? What about penetration?

This is the most concern of many netizens. Everyone hopes that the wireless signal can penetrate at least the partition wall in the house. To improve the ability of the wireless signal to penetrate the partition wall, the effective way is to increase the gain of the antenna. It is best to choose products with high antenna gain, generally at least 2 dBi or better. According to experience, the gain antenna signal of 2dbi can penetrate two walls? If there are too many rooms, there are more partition walls. The device is detachable antenna, in order to configure a high gain antenna, such as changing the 5dBi omnidirectional antenna to enhance it?

Obstacles of metal objects not only block microwave wireless signals, they can also absorb electromagnetic energy and generate weak currents to drain away. Therefore, the largest obstacle for metal objects in the home environment without wireless signals is the presence of steel bars. On the floor of the network, the signal in this direction is almost impossible to penetrate? To be able to penetrate, the signal is also very weak? Such a large obstacle, the diffraction of microwaves is even more impossible? In the center of the house, the wireless signal can only be emitted straight from the window through the open channel?

After we all know the above factors, we have to choose an optimal place for the wireless AP? The requirements for this place are as follows:

1) The position should be higher, so as to radiate downward at a higher place, reduce the obstruction of obstacles, and minimize the signal blind area;
2) The location point selection should make the signal pass through the partition wall as little as possible, preferably the wireless client in the room can be seen between the wireless AP?

So the best placement point of wireless AP at home should be in the living room, and it can be best seen with the computer host in the room?

3. Wireless LAN performance

With the rapid development of wireless local area networks, users have run more and more key applications on wireless local area networks, so many common high-bandwidth consumption applications such as video applications require wireless local area networks to provide higher bandwidth. In order to achieve high-quality performance! We know that the wireless AP device is a "wireless sharer", they jointly access the wireless client device, running Ethernet CSMA / CD (Carrier Sense Multiple Access / Collision Detection) It is clear that it is a "shared" network, the same network working principle as the previous network hub, but the cable of the hub is abandoned, and it is changed to wireless?

Such a shared environment is an inherent drawback of wireless LANs, so to use the current network applications smoothly and normally, the general recommendation is that a wireless router or wireless AP can only access up to 30 wireless clients? Transmission performance will be greatly reduced? It seems that home users generally do not have so many wireless clients, so the wireless LAN is completely acceptable to the family? But the wireless network should try to avoid using BT? EMule and other P2P downloads Software, because it is possible to paralyze the entire wireless network?

BT eMule uses the method of file segmentation and multi-point transmission to improve the transmission speed of files? The BT software will first divide a file into several parts on the uploader side and provide it to the user to download? To download the divided files in order, the remaining part of the download does not have to go to the uploader's computer, but can be downloaded to other downloaders through the distributed cross download program of the BT software? In this way, the downloader is in At the same time of downloading, it also undertakes part of the upload work. Downloading and uploading are synchronized, which greatly improves the download speed of the file, but only if there are many people downloading the same file at that download point at the same time. When downloading, will the download speed be fast?

BT download is more generally considered to be a heavyweight killer of bandwidth. This is precisely the biggest reason given by many broadband operators when they announced the ban on BT. In a shared network, if BT download is used, it will be Other Internet applications have caused a great deal of occupancy, making the overall network speed slower or even a big traffic jam?


As long as you can correctly understand the wireless characteristics of wireless LANs and wireless APs, deploying wireless networks at home can be very comfortable? Let us summarize the factors that affect the wireless network: avoid wireless devices in the same frequency band in the wireless network area, avoid wireless Channel interference? The wireless AP should be placed in a higher location, as visible as possible with the wireless client, avoid blind spots, avoid too many partition walls, and avoid being blocked by metal obstacles? Since the wireless network is a shared network, it should be Avoid using large traffic, or even BT download software that causes network congestion?

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