如果你對在家裡使用Wi-Fi還不熟悉，那麼當你的裝置連線到路由器時，你可能會對它的工作原理感到好奇。有鑑於此，今天的超級使用者問答帖子為好奇的讀者提供了答案。

今天的問答環節是由SuperUser提供的，SuperUser是Stack Exchange的一個分支，是一個由社群驅動的問答網站分組。

照片由Scott Beale（Flickr）提供。

問題

超級使用者閱讀器1.21千兆瓦想知道Wi-Fi路由器天線是否相對於與其相連的Wi-Fi裝置“旋轉”：

Do Wi-Fi router antennas rotate their direction based on the location of the device they are talking to (i.e. based on MIMO, triangulation, and other factors)?

For example, if I keep my device still and in one location, will the transfer rate go up?

Wi-Fi路由器天線是否相對於與其相連的Wi-Fi裝置“旋轉”？

答案

超級使用者貢獻者JakeGould為我們提供了答案：

Shorter Answer

Physically, router antennas do not rotate. But logically, beamforming technology allows some MIMO routers to shape the tran**ission/reception power from the router to your device that is connected via 802.11n or 802.11ac.

If you are concerned about whether the act of physically moving connected devices around affects data tran**ission/reception, it might theoretically affect speeds in some way, but on a practical level it might not be worth being concerned about. More details below.

Longer Answer

Do Wi-Fi router antennas ‘rotate’ their direction based on the location of the device they are talking to (i.e. based on MIMO, triangulation, and other factors)?

Do Wi-Fi router antennas rotate? Well, I am not aware of any that physically rotate like the ears of a cat, dog, or even Robby the Robot from Forbidden Planet.

That said, if the Wi-Fi router uses a multiple antenna array, it can use beamforming technology to effectively “shape” the way data is received and tran**itted from the router’s antenna array. As Wikipedia explains (bold emphasis is mine):

• Beamforming or spatial filtering is a signal processing technique used in sensor arrays for directional signal tran**ission or reception. This is achieved by combining elements in a phased array in such a way that signals at particular angles experience c***tructive interference while others experience destructive interference. Beamforming can be used at both the tran**itting and receiving ends in order to achieve spatial selectivity. The improvement compared with omnidirectional reception/tran**ission is known as the receive/tran**it gain (or loss).

This general concept is used in MIMO-based networking techniques as explained in O’Reilly’s “802.11ac: A Survival Guide” (again, bold emphasis is mine):

• An alternative method of tran**ission is to focus energy toward a receiver, a process called beamforming. Provided the AP has sufficient information to send the radio energy preferentially in one direction, it is possible to reach farther. The overall effect is illustrated in Figure 4-1 (pictured here). Beamforming focuses energy toward a client, such as to the laptop computer at the right side of the figure. The wedges illustrate the areas where the beamforming focus increases power, and therefore the signal-to-noise ratio and data rates. The mirrored preferential tran**ission to the left is a common effect of focusing energy in a system with limited antenna elements. However, focusing the energy toward the left and right sides of the figure means that the AP’s range in other directi*** is **aller.

That said, beamforming is not a magical cure for Wi-Fi signal loss/strength and works best at medium ranges (once again, bold emphasis is mine):

• Beamforming increases the performance of wireless networks at medium ranges. At short ranges, the signal power is high enough that the SNR will support the maximum data rate. At long ranges, beamforming does not offer a substantial gain over an omnidirectional antenna, and data rates will be identical to non-beamformed tran**issi***. Beamforming works by improving what is called the rate over range—at a given distance from the AP, a client device will have better performance.

So when you ask the following question:

For example, if I keep my device still and in one location, will the transfer rate go up?

Maybe it will, maybe it will not. You can experiment, if you wish, with moving around a room versus standing still. First, check to see if your router actually has beamforming capabilities and if they are enabled. But honestly, you might be trying to squeeze blood from a stone here for minimal gains.

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