But what if we have to reuse our channels where we have more APs on same floor or different floors. By changing the power from 18dBm to 1dBm we have reduced the interference but we can see interfernce still exists. We can clearly see that our want area is greatly affected. It shows that you can not always fix bad Wi-Fi design with tweaks such as power in our scenario. Always use best practices for Wi-Fi design and then validate by post installation survey. Try to use appropriate antennas for every deployment.
With directional antenna you can control RF much better as compared to Omni antennas. Higher transmit power will give you longer RF tail and we can decrease the long RF tail by reducing access point power but same time its necessary to check that how it will effect coverage. Save my name, email, and website in this browser for the next time I comment.
Don't subscribe All Replies to my comments Notify me of followup comments via e-mail. You can also subscribe without commenting. As Keith suggested that we should break down the area in 3 different areas.
Want 2. This is the trickiest of the 3 parts mainly due to the fact that it can be expressed in Watts, Milliwatts or dBm. Ideally you want to convert this to a dBm value if not already expressed this way. Converting Watts and Milliwatts to dBm is slightly more tricky… You are now entering the wonderful world of logarithmic calculations! You will need to take into account the loss caused by cables and connectors as each component will add an element of loss.
Also keep any antenna cable lengths as short as possible. Normally loss values will be expressed as dB loss per ft and you can typically find this value on the spec sheet. This one is easy, simply look up the dBi value of the antenna and apply it to the calculation.
Doubling the distance lowers the radio energy to a quarter. Cell phones use more power and they are safe to keep next to your head. You start at 0 and end at 8. I thought everybody knew This way the speed may be different in each direction or for each packet sent, actually. All these tries and retransmissions will eat air time from other clients.
This should not be included as a point. Maybe add this content in the beginning, not within a point. Only applicable to setup with multiple routers. Access points being cheap is subjective. For third world countries like mine, routers and internet subscription is still expensive. No thanks, effects are worse. I just wanted to set straight a common misconception. It is common to have multiple APs even in larger homes.
This applies in a single AP scenario as well. If you consider them to be expensive now then they were really expensive just a few years back. This point is about multi AP environments where your own APs will interfere with each other if they are using too much power. Amplifiers will distort the signal at max power. The point is that there is no advantage in using excessive power. Wi-Fi is not a competition. The APs are not trying to yell louder to overcome the other.
They are taking turns as long as they can detect each other. Interference or turntaking with your wall neighbors is almost inevitable. However, interference across the street is pointless. You gain nothing and you are making life harder for others.
I was living and working in IT for years in the third world countries such as Cambodia and Thailand. With their yours low-speed plans and limited access they you unlikely need for high-performance Wi-Fi AP do not be confused in this IT terminology.
I could trow cable from window to window or easily drill a hole trough a walls in Cambodia without consents and complains. BUT… But being in New Zealand I can not do so — need for consents, certified carpenter, electrician, painter and so on.
And my WiFiAnalizer shows me overcrowded 2. My WiFi-router sits at one end of the house and my workstation with 4K TV as monitor at another end and they connected by means of radio bridge affordable MikroTik APs. I found this article very helpful but your complains exaggerated. Could not stop from writing it even my time are pretty valuable for me and my family.
Most important: be patient and calm instead of being blunt and arrogant. Read, watch and do hands-on labs as much as possible before you come to teach professionals who went as far as you can not imagine and you will definitely be able to grasp more knowledge. Cheers bro, take care! Petry, I take my hat off before your expertise and willingness to share your skills and experience. Thanks a lot! Can you please provide a list of routers that allow output power adjustment….. No, there are so many APs on the market and new ones introduced every month.
However, most of the APs I have looked at do have transmit power adjustment, even consumer grade devices. Some let you set a decibel value, some have percentage and some have hard coded levels.
I suspect this relates to 2. In that case, for the 5. Applying your recommendation to set Tx Power 6dB stronger in the 5. Finally, I would be very interested in another of your very hands-on posts or a good reference that would cover the typical attenuation losses from typical obstacles in a house, e.
Elements of information that are missing are for example: a. I would use 14dBm for 5GHz and 8dBm for 2. After surveying I may need to change some local setting.
My advice is to start with low power and increase it if needed. Even better if you start out with 10dBm for 5GHz and 4dBm for 2. I would use 6dBm less for 2. All walls are different: a simple dry wall with gypsum boards attenuates typically dBm if the frames are wooden. Metal frames create odd patterns of attenuation. All glass panes behave differently, especially if they are tinted. Wall thickness is simpler. Doubling the thickness doubles the loss, if the construction is the same.
Same goes for angles: Waves going directly through travel the shortest distance inside the wall thus attenuate least. Deviation from straight angle increases the attenuation. Set up an AP on the same side of the wall as you are. Check the signal level with some tool. Next, move the AP just to the other side of the wall less than a foot or 30cm.
Check the signal level from the same spot. You are only interested in the difference. It have settings for transmit power. It can also run custom firmwares.
It could also block signals from the outside. Yes, metal will block signals but it will also reflect. If you have a reflector close to the antenna in terms of wavelength you will get very interesting interference patterns.
Your coverage area will be completely different from what you would expect. Place the metal sheet at least several wavelengths 12cm for 2. Look up Fresnel zone, too, and note it extends well beyond the antenna. Designing antenna reflectors is a very complicated subject. I would assume you could google for introductory papers, but it will take years of study to learn.
I have a friend who wrote his doctorate dissertation on antenna design. Life would be easier if we had some handy materials to absorb microwaves, but stone and concrete are difficult to add afterwards. A body of water would also work, but is hard to place or maintain. The main, and only meaningful, reason to reduce router transmit power is to avoid adverse health effects.
Non-ionizing radiation DOES cause biological effects, even at lower signal strengths. Yes, it actually does. It heats up tissues. That is how microwave ovens work.
The difference is in the power. Ovens use typically Watts while Wi-Fi devices use 0. In the text I suggest lowering that to 0.
However, the power attenuates quickly with distance. Unless you sleep with the access point under your pillow your only concern should be the client device, which is close you.
The AP transmit power plays no role because of the distance. Especially at night when our cells regenerate and heal. Ionizing or not, the health studies are not properly conducted to account for these real-world scenarios, and is frankly irresponsible science to rely on!
RF and EMF exposure will be the new smoking as we move foreward. The title suggests turning it down. In the previous comment I explain that because of the distance the AP transmit power is insignificant when compared to the client device next to the user.
If you are worried about RF radiation you should keep your cell phone in flight mode all the time. There are no bursts or spikes of radio energy in Wi-Fi. The transmit power is at a constant level, which is used when there is data to send. If there is no data there is no transmission. In an apartment complex the paths are not free but there are walls in-between, which will attenuate the radiation even more.
Wi-Fi is not encoded in on-off. Think of it more like light: red light is one and blue light is zero. The problem with on-off encoding is that a missing signal is interpreted as a stream of zeros.
Thank you for your input.. Now I know why my center with 32 APs is having low signal or no signal at all or areas where signals drops and comes back.. Do you think that 1. Do not place the APs behind or between the pipes. Metal will block and reflect signals. Uniform reflections are not a problem, but a pipe array will cause scattering like a disco ball. Hi Petri, thank you for sharing these very interesting thoughts.
I cannot quite understand the point 1. If a typical mobile device does a max TX power of 15mW, and a typical AP does mW — what is the reason for such a disparity? However, slightly higher AP power makes sense, since often most of the traffic is downloading.
In that case it makes sense to have a better connection in one direction. If you have a mixed environment like most are you are hurting the laptop users if you set the AP power to 15mW.
The laptops get shorter range and worse rates than they would get with higher AP power. This can be solved by adding more APs so the range will always be short, but it costs more money and takes more effort to administer.
Hi Petri, thank you for your advice. It is missing all 4 antennas, however. Thank you! I strongly recommend low gain omni antennas, unless you really need directionality.
Dear Petri, Thank you so much for taking your valuable time to explain all these points. I find your intelligence and manner to be excellent and have learned so much reading all that you have to offer. I am very grateful to you and wish you all the best. Perhaps an adapter with a shield cover that can be velcroed onto something? The power levels are very low and there is always some distance.
The signal attenuates very quickly with distance. If anything, the only microwave device you carry next to your body, day after day, is your cell phone. There are activist groups in many countries attacking cell towers, because they are afraid of the radiation. Yet they carry their own transmitter next to their bodies. Very few people read and write letters in candlelight. You need to log in to the AP, typically with a browser. The address, admin user and password are typically in the sticker at the bottom of the AP.
Hi Petri, first thanks for all info. The power levels are very low and there is always some distance to the AP. For technical reasons described in the post you should run your AP at as low power as is possible while keeping the network functional. If you wrap aluminium around the AP antennas your client devices will increase power to keep connected to the AP. Completely the opposite of what you are trying to achieve.
Thanks for this excellent, informative, and well-written post. As well for your attentive responses to comments, several of which responses exhibit the patience of a saint! Instead, in my case I have discovered that a devious neighbor has hacked into my router. What might be possible disadvantages to doing so? Needless to say, I have ample speed and coverage in my house and my yard.
Is there any downside to removing the router antennae entirely? You can go as low as the AP still keeps working. At some point the circuitry will cease functioning.
Removing the antenna is a bad idea. It will help to avoid drawing attention, but if you are targeted, then a directional antenna can pick up the signal. Use good passphrases and keep your firmwares up to date instead. Thanks for the advice. I had no idea that weak signals could be targeted like that. Thank you for this very informative article.
Your article helped me optimize the wifi in my home. I was struggling with thick concrete walls and heavy steel doors separating three rooms where I needed the signal to reach. Thankfully, each room has a wired connection leading back to a single router.
Of course, all SSIDs and shared keys are the same so devices can roam easily. Well done! As to your question: No, in the same room 2 mW provides a good signal. I presume you have full Wi-Fi bars on your phones? In no case will the client try to increase its transmit power. Hello, Petri. Now the 2mW transmission power previously set for 2. Thanks for your time! Petri, You are very much appreciated for your valuable advice.
If so, can we use an iPhone to get a general idea of the signal quality in areas we suspect interference from devices or defective appliances? They are crude at best, often misleading. The apps can only see a network connection, but no details. That makes iOS a poor platform for Wi-Fi tools. The best app I have used is Wi-Fi Sweetspots.
Newbie here. Is there a preference? The one I meant was by farproc, but it has been a while. Some apps get acquired or changed. Some comment mentions the current version tracking your location, which is totally unnecessary.
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