multiple access points on different channels

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learning_network

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We have 5 wireless devices(routers con as Access Points) very close to each other running on different channels like device1 on channel1, device2 on channel2, device3 on channel3, device4 on channel4, device5 on channel5.

My concern is if it is affecting our throughput, shall I need to make any changes in regards to channel?
 
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RealBeast
As bill001g says, this does get complex with...
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RealBeast

RealBeast

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I assume that all of these are on the 2.4GHz frequency, and not on 5GHz.

It is definitely affecting your speeds, as they will interfere with one another. Use non-overlapping channels for three of them (1, 6, and 11) and then use one of those channels for the other two that are farthest away from an AP using that channel. A partial overlap can cause more interference that using the same channel.

I would question the need for 5 if they are all together -- use three and your results will be far better.

If you explain why you use 5, there may be other steps you can take.
 
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learning_network

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Three of them are under 802.11g mode, and the other two are under mixed mode. Well, when we had just two earlier, we had an issue of some storeys not getting proper signal with only two bars. Then we added one, further one, and recently one more in another storeys of our building because we thought adding APs will extend range and help to get signals for everyone in the building.

So you mean I have to use 1, 6 and 11 for 3 APs. The other two should also be using one of these three channels only (1,6 and 11) but farthest away from each other.

I just got a question on this, as you know I'm using different channels already for each device, why do you think it will cause interference?
 
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bill001g

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This subject gets complex very fast.

The number 1-11 represent frequencies of radio you can use. These are spaced 5mhz apart. So if we had some wireless signals and they could fit into 5mhz then you could have 11 radios running. Problem is the signals are just about 22mhz wide with the overhead. This means you need 5 of these kinds of channels to represent a single radio channel. This is why 1,6.11 are chosen but very technically it is transmitting 11mhz below channel 1 and 11mhz above channel 11.

What is even worse is to get 150m you must use just over 40mhz. This means you can really only have a single AP using 40mhz and not overlap on the 2.4g band. When you go to 802.11ac it uses 80mhz which is larger than the complete 2.4g band so you are only allowed to use it on 5g.

What you want to if you AP have the ability is reduce the power to avoid overlapping. You want the AP power to just be strong enough to provide good signal for the area it is used for but not any further. This allows you to place AP on the same channels closer together.
 
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RealBeast

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As bill001g says, this does get complex with more than 3 wireless radios on 2.4GHz. I would use a network analyzer to determine which two wireless radios are the farthest from a strong signal that comes from two of the other radios.

You can take a look by walking around with a laptop running inSSIDer free from HERE to get a rough idea of the signals. If there is a very weak signal, say -80dB or worse, you should be okay to use the same channel on the radio in that area. You will likely have interference issues in areas that get a strong signal from two radios on the same channel. The idea is to stagger their implementation so that there is little or no overlap. Not always possible, but then question your need for the additional APs or considering turning down their broadcast power to minimize the interference.

Take a look at the channel picture HERE and you will see that channels 1-5 all overlap with one another.

 
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learning_network

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Thank you bill001g
It seems Frequency band and channel stuff is a wide topic. I got the gist of it from your explanation. I will look it up on Google for more details. In the meantime, I changed three of my APs to have channel 1,6 and 11 respectively which are closer together. The other two are little bit father away from the other three, which I changed to (6 and 11).
Also I disabled the "Extended range" option from all Ap, and changed the Transmit Power option from ("Max" to 1/4). Do you think it will add any benefit?
 
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RealBeast

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Once you start the inSSIDer program, if you click on the Network tab, it will list all 2.4GHz radio signals within range and list their SSID (name), strength, and channel.

 
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I checked with inssider , there were many SSIDs on same channel around our area. Most of them do not belong to our network, it is somebody else in my area. I wonder then how can I adjust it. I will be able to adjust the ACCESS POINTS that belong to us only.
 
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RealBeast

RealBeast

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That is a big issue with wireless, everyone uses 2.4GHz and 5GHz is starting to get more use. You can't do anything about the wireless that isn't yours. Some places, 2.4GHz is not even worth setting up and you need to use 5GHz.

 
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learning_network

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Thanks Realbest. My question is whether this intereference is affecting my internet speed or it is affecting just getting good signal.

And one more question if I use 5 GHZ which channel shall I use? And will it cause interference with 2.4 GHz?
 
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bill001g

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I will butt in here and try to explain.
The signals will tolerate some amount of interference but it degrades rather quickly. The example I tend to use is if you were to take 2 radios and play them on different stations as loudly as you can. You will hear both very loud..ie good signal level but will have a hard time actually getting a good listening experience from either..ie quality.

Interference on wireless causes data to not be received clearly which then causes the radios to retry to send the data. This resending of course increases the total data sent which many times will cascade into all the radios fighting and nobody getting any data though which will drop sessions.

5g you have much more selection of channels to a point. Unfortunately that huge list of channels is partially untrue. There are the 4 lowest channels that all can safely use. There are also 4 or 5 on the top that are allowed in some countries. All the rest in the middle are a random risk if you can use. They must turn themselves off if they detect weather radar on the same frequencies and you never really know when a tv station or whatever turns on their radar. Some routers do not even allow you to set these channels mainly 52-140.

To make this even worse the new 802.11ac needs to use blocks of 4 channels which means almost everyone is using the bottom 4 or the top 4 to be safe. So just like 2.4g everyone is stomping all over each other and nobody gets anything.

Now it is not really that bad. One of the good and bad things is 5g does not penetrate walls as easy which means your neighbors signal is much weaker and causes less interference inside your house. Check with INSSIDER on the 5g but you will not see 802.11ac unless you have a 802.11ac nic card. I would tend to try the channels 36-48 or 149-165 first and then next 52-64. Most weather radar is in the channels around 120 but this varies greatly from country to country and even parts of countries.
 
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