topic Re: Hello, in Wireless

Per client bandwidth calculation help

istvan.kelemen1 — Mon, 05 Jul 2021 11:35:34 GMT

Hello,

Assuming that "Air Time Fairness" is on, how can I calculate the real bandwidth per AP per channel?

Let's say we are on 5Ghz. Channel for N is set to 40Mhz, for AC is set to 80Mhz. GI is set to short.

4 clients are associated at 877.5Mb/s, 5 clients are associated at 450Mb/s and 7 clients are associated at 300Mb/s.

What would be the maximum per client throughput when all the devices are talkin at the same time?

How to calculate it?

Thanks you,

István

Well, there are 16 clients

Philip D'Ath — Sun, 07 Feb 2016 06:36:44 GMT

Well, there are 16 clients attached. Maximum per-client bandwidth would be achieved if 15 of those connected were silent and did not generate or send traffic. The maximum throughput would happen on the "best" connected client.

So I would say the maximum per client bandwidth in this case would be 877.5Mb/s.

Hello,

istvan.kelemen1 — Mon, 08 Feb 2016 11:34:52 GMT

Hello,

I have a theory.

Let's assume that max 5G rate may be 1300Mb/s and 2.4 may be 216.7Mb/s.

In this case the real BW would be 650Mb/s and 108Mb/s respectively.

So the max BW what AP would require may be 758Mb/s when the clients are associated at the highest speed, regardless of the number of the clients.

Let's take a real word example, assuming Airtime fairness is enabled.

For simplicity, let's say all the clients transmit for 1 second in a round-robin fashion.

Case 1, mixed clients:

5Ghz:

Client 1 : 1300Mb/s associated rate - 650Mb is sent

Client 2 : 877Mb/s associated rate - 438Mb is sent

Client 3 : 780Mb/s associated rate - 390Mb is sent

Client 4 : 292Mb/s associated rate - 146Mb is sent

Average speed in 4 seconds is: 406Mb/s

2.4G

Client 5 : 216Mb/s associated rate - 108Mb is sent

Client 6 : 144Mb/s associated rate - 72Mb is sent

Client 7 : 72Mb/s associated rate - 36Mb is sent

Average speed in 4 seconds is: 72Mb/s

Total AP average BW: 478Mb/s

Case 2:

5Ghz:

Client 1 : 1300Mb/s associated rate - 650Mb is sent

Client 2 : 1300Mb/s associated rate - 650Mb is sent

Client 3 : 1300Mb/s associated rate - 650Mb is sent

Client 4 : 1300Mb/s associated rate - 650Mb is sent

AVG: 650Mb/s

2.4G

Client 5 : 216Mb/s associated rate - 108Mb is sent

Client 6 : 216Mb/s associated rate - 108Mb is sent

Client 7 : 216Mb/s associated rate - 108Mb is sent

AVG: 108 Mb/s

Total: 758Mb/s

Let's add few more slow clients:

5Ghz:

Client 1 : 1300Mb/s associated rate - 650Mb is sent

Client 2 : 877Mb/s associated rate - 438Mb is sent

Client 3 : 780Mb/s associated rate - 390Mb is sent

Client 4 : 292Mb/s associated rate - 146Mb is sent

Client 5 : 292Mb/s associated rate - 146Mb is sent

Client 6 : 292Mb/s associated rate - 146Mb is sent

Client 7 : 292Mb/s associated rate - 146Mb is sent

Average speed in 4 seconds is: 294Mb/s

So my conclusion is that slower clients slow down all the faster clients which are connected to the same AP Radio in a directly proportional fashion.

Am I correct?

Yes, you are correct.

Philip D'Ath — Mon, 08 Feb 2016 20:21:55 GMT

Yes, you are correct.

Re: Hello,

csco10675262 — Thu, 08 Feb 2018 04:11:43 GMT

Apologies on hijacking the thread as its been some time. I am curious and wondering on how the values are dervied? Is there a methodology/forumul for it?

Appeciate for the help 🙂