First of all, we all know that the antenna of the earlier generation of industrial-grade wifi routers will certainly not exceed one. So it seems that 802.11n has clearly become a watershed, and since then the antenna is no longer a solitary one. What exactly is the matter? Here we will refer to an 11n protocol before it is applied. The multi-antenna technology is also a very important technology in the field of wireless communications - multiple input multiple output (MIMO).
Some people say why did I buy a latest 3-antenna industrial-grade wifi router supporting 802.11ac protocol, and the result is that the signal strength, coverage, and even speed are not up? The antenna is not enough? In fact, we have to check that you use The receiving end support does not support the AC protocol. For example, if you are using an earlier iPhone 3, this phone can only support 11a/b/g even 11n, so even if you add a few antennas to this cargo, it is no use, just add an AC network card Or change the terminal on the line.
Why do you say this? If the Wi-Fi application environment is indoors, our commonly used 802.11 series protocols are also built for this condition. Since there are various obstacles between the transmitter and the receiver, there is almost no possibility of direct signal transmission and reception. Then how do we manage this method called multipath transmission, also called multipath effect. Multipath, which is also well understood literally, is to increase the transmission path.
Since it is multi-path, the distance traveled may vary. Some may be reflected from the table, some may be through the wall, and these signals carrying the same information but having different phases may eventually be collected together at the receiving end. . Modern communication uses packet forwarding for store-and-forward, also called packet switching, and transmits symbols. Because of the different transmission delays caused by the obstacles, ISI (InterSymbolInterference) is caused. To avoid ISI, the bandwidth of the communication must be less than the reciprocal of the tolerable delay.
Finally, the perception of the strength of the wireless signal is also reflected in the user's receiving device. If the receiving sensitivity of the device is not high, then the user will feel that the wireless signal is not good and the actual experience of the Internet will be poor. In other words, I shipped 100 barrels of water to the door of your home warehouse. Your warehouse was in disrepair for a long time and the door was small. You can only move a bucket of water at a time. Of course, it will not get up! !
Therefore, for most industrial-grade routers, multi-antennas are not equal to strong signals, let alone large walls. Hope this helps people who need it.
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