Is it a viable solution to increase Tx power of AP if network is crowded?

Question

We are going to provide Wi-Fi (802.11b/g/n) to a small building with a dozen APs, one AP per room. The rooms are adjacent to each other. Each AP will independently have its own SSID protected by WPA2 shared key, and will be used concurrently by 20 clients (consumer-grade tablets).

We've been asked if we could increase the transmission signal power from the APs - provided that the firmware allows it - for "a better reception" (as APs can increase bandwidth by reducing transmission range, and transmission power is directly proportional to range).

I have some doubts about it, considering that:

• Increasing transmission power will enhance its range, making it more likely to interfere with the other signals from the other APs;

• Concerning the point above, many network devices in fact implement Transmit Power Control (TPC) to lower signal power in order to reduce interference with other wireless networks;

• Trying to increase signal range makes sense to try to reach far clients. Here, it is important that the AP signal is heard only from clients in the same room;

• We can increase APs Tx power but - most likely - not clients', therefore the increase in range would be just mono-directional.

I know that the correct answer to this kind of questions is "it depends"; however, I'd like to know if there's something I am missing, or it is indeed not worthy to try to boost Tx signal given this specific configuration.

Answer 1

Generally speaking, if you have a wireless network dedicated to each room then increasing the transmit power will have more of a negative effect than any positive effect.

The only case where you may need to consider this is if you are in an environment where the noise floor is extremely high for the 802.11 frequencies. In this case you may need the extra power to have a sufficient SNR for a good connection.

As you point out in the question, increasing the transmit power will increase the visibility with other access points, meaning that the airtime will be divided between all the access points on the same channel. This can have a significant performance impact which worsens the user experience. Decreasing the transmit power so that fewer "neighbor" APs are seen can improve performance and the user experience.

However the best approach it to do an actual survey of the area (including spectrum analysis) and monitor performance statistics from the wireless environment.

Let me also add that you said, "We've been asked if we could increase the transmission signal power from the APs...." However, you do not mention why this suggestion was given to you. Is there actually some sort of problem that users are experiencing? Usually if someone makes a suggestion like this, then there is a reason and maybe you need to look into the reason behind the suggestion.

Answer 2

Depending on your vendor solution, you may want to implement a wireless management solution that will provide the services you want to deliver to the clients. That includes power management, RF management, SSID management, etc...