The list of wifi channels are presented here. My question: Let us assume that I have two Access points. which of the channels listed are used by which Access point? and how many users are supported per each Access point? are users allowed to send data concurrently to the access point (in other words, how many users can the channel hear at once?) Thank you.
1 Answer
Which of the channels listed are used by which Access point?
For best results, only 1, 6 and 11 are used in the 2.4GHz band. Typically, you would not have the two access points on the same channel because they would tend to interfere with each other. You can manually select the channel, or some APs will pick the "best" one.
How many users are supported per each Access point?
That depends on the model of access point and the amount of bandwidth each user requires. Cisco APs will allow up to 256 clients to associate, but normally you would saturate the channel long before then.
Are users allowed to send data concurrently to the access point?
802.11 is CSMA/CA, so each client waits until the channel is clear before sending. In short, no.
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So that means, a single channel(say channel 1) can be used by 256 clients turn by turn in the time domain. right?– SrayCommented Feb 13, 2015 at 8:27
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Ok thank you. Let's assume channel1 is selected by Access Point 1. So, channel1 has a certain bandwidth, say B. can you show me the calculation that shows 256 or certain number of users are allowed to access the channel? in other words, I want to know how much is allocated for each of the users and how?– SrayCommented Mar 23, 2015 at 5:47
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It's not that simple or deterministic. And by that question, I see that you don't quite understand CSMA/CA yet. Watch this first: youtube.com/watch?v=-f_Hk1RpmN4 Commented Mar 23, 2015 at 10:26
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okay I got the point, I think. Any number of users can use the channel as long as they sense the medium free and there is no collision. right? But what about the cellular network case? I think there is no CSMA/CA protocol there right?– SrayCommented Mar 25, 2015 at 5:43
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I confess to not having spent the time to learn the protocols used on cellular telephone networks. But I'm sure if you spent some quality time with Google, you could find out all you've ever wanted to know. Commented Mar 25, 2015 at 11:58