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I always has this question in my mind.

For example, FM Radio Station and Radio player, strong signal from Radio Station could help, because Station --> player is one direction only communication.

  1. But in the case of WIFI, is it the same? high power wifi from router could be helpful?

  2. What if router wifi --> computer is very strong, but computer wifi --> router is very weak.
    The network feedback from computer back to internet will fail anyway, no matter how strong is the router?

  3. Am I understanding is correct?

  4. So.....Repeater is a must to solve weak signal problem?
  • Thanks YLearn and all other friends. I get new knowledge from all of you. Thanks a lot. – user2503 Aug 30 '13 at 2:57
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What you are describing is an imbalanced power situation, where one station (the access point) is transmitting at a higher power setting than the others. Increasing the transmit power of the AP will not really increase your coverage as your client has to be able to transmit back to the AP as you indicated.

However, if the majority of your traffic is downstream (from AP to client), then this can sometimes increase performance. The reason this can help is that the larger data frames (in this case the majority of traffic) can be transmitted and received more reliably at higher data rates, with less retries/loss.

Be careful though as this can also lead to a number of situations where you will actually hurt your performance. For instance, setting the transmit power too high (higher than the manufacturer intended) can increase the distortion of a signal (especially with cheaper hardware). In addition, some hardware will not allow you to increase the transmit power above a certain point, even if the firmware seems to indicate you can.

Generally, you are better off using a passive means of producing gain, such as a higher dBi antenna. This will produce an increase for both transmit and receive signal strength. Make sure you understand how this will affect your environment (for instance a higher gain dipole will get you more signal strength on the horizontal/azimuth plane than a lower gain dipole, but it reduce the vertical/elevation providing less coverage above/below the plane of the antenna).

As for a repeater being a must to solve weak signal problems, I have found that often repeaters create more problems than they solve. They will typically decrease performance of a busy wireless network and can introduce other problems as well (hidden node, etc).

Instead of repeaters, I would recommend additional APs to provide additional coverage. You can do this by planning the placement of the additional APs or using directional/semi-directional antennas forming an "AP array" from a central location.

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Your understanding is generally good.

There is one place (that I know of) where higher than standard power is/can be of some use - and that is where you are making a connection between two devices BOTH of which can run at higher than normal power. Of course, this also makes them more prone to interfere with other devices. In a rural environment where you have, for some reason, no cable/fiber between buildings, or getting fiber between buildings is on the plate but you need network before that, a dedicated pair wireless link (preferably with both ends also using horizontal polarization and directional antennas, so they interfere less with normal AP traffic that tends to be vertical polarized) can be of use.

End-user computers would NOT be connecting to the link in this case.

But. Fiber beats the heck out of that all day every day. It's a temporary expedient at best, IME; I have done both.

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Also I want to share one more case in addition to the brilliant answer of YLearn.

When you have powerful signal you get a better coverage. But not always a better coverage is better for you. The better coverage allows more client devices to connect. More client devices make more load on your access point.

So I'm agree with YLearn. You need to add more AP to get bigger coverage.

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    In fact, some enterprise APs have advanced features that turn down the power so that the clients get spread out between the APs and don't overload a specific one! – chrylis -cautiouslyoptimistic- Aug 29 '13 at 12:28
  • @chrylis Yes, you're right. So I wrote in my answer second reason for such behavior. – Pavel Aug 29 '13 at 15:48

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