Does the number of users affect wifi network speed (not internet)?

[Lechu1777]

Hi,

I have a question for you. If I have for example 100Mb/s internet speed connected to WAN port of a router and the router has only WiFi G, can I connect 5 wifi G hosts and all of them reach max G standard speed using the Internet (~20Mb/s) which combined equal 100Mb/s internet speed? Or numbers of users devide max G speed (20/5=4Mb/s)? To my mind, I believe all hosts should reach 20Mb/s, but I have to be sure.

Cheers

 

[RealBeast]

Yes, the number of users affects wireless speed.

The bottleneck in your scenario is the wireless radio bandwidth, which will be some amount less than the maximum theoretical speed (less overhead and interference) divided among the users. It will not be divided evenly though, unless all users are identical in equipment, position, use, etc. -- so basically it won't be even. One user may consume all the available bandwidth and leave the others with little to none. An example would be a user sitting next to the router and streaming full HD video, they would consume most of the bandwidth.

 

[Lechu1777]

So you're saying that having 100Mb/s internet connected to WAN port (usual) + G router means that in fact I have only 20Mb/s (G practical speed) to share between hosts? And all hosts combined will reach only 20Mb/s out of 100 using the Internet?

 

[bill001g]

That is exactly the problem. You must think of the wireless as a single port on the router and that total bandwidth must be shared between all the users. Part of the reason wireless performs so badly is because of this ineffective sharing. This is almost the equivalent of taking a old 10m hub and hook it to a wired port on the router and then hooking all the users to the hub. They would have to share the 10m connection between the hub and the router and since this is a hub rather than a switch when they start to send a lot of data they transmit all over the top of each other degrading the performance even more.

The only way to get around some of this is to use multiple radios so in the example you use you could run 20mb/s on each radio. This of course only work to a point since there are only so many non overlapping radio frequencies you can use.

 

[Lechu1777]

Okay, it's just pure theoretical since we have N as standard nowadays and that's why I haven't given second thoughts about the problem. Hmm so what about N MIMO 2x2, then? For example 2 hosts 2x2 MIMO + 1 router 2x2 MIMO. The setup would reach 150Mb/s, so 75Mb/s / host, because we have actually 2 streams? I use practical speeds, 150(300 sync) and 75(150 sync). Still not so great. Does 5Ghz A or AC solve the problem?

 

[bill001g]

Nope the streams do not go to separate users they are overlapping streams to the same user. The 5g just gives you different channels to use. The very latest 802.11ac has something called beam forming but I still think even that is switch very quickly between the users rather than simultaneous transmissions. Hard to say this is a very rare feature since most 802.11ac routers where put out before that feature was stated to be in the standard.

The only advantage to a faster transmission rate is that the users can take turns faster and the chance of them overlapping is less. Still at some point it degrades.

Now a dual band router since most have 2 radios can have one signal on 2.4g and one signal on 5g at the same time. Still it is only so much bandwidth per radio in the router. They do make high end commercial AP that have 6 or more radios.

 

[Lechu1777]

Ok, nice answer. You're writing about dual band routers. So are dual band wifi adapters able to work simultaneously (like routers) 2,4+5 to enchance one host bandwidth?

 

[bill001g]

Nope dual band adapters only have a single radio chip that can run 2.4g or 5g you must choose one or the other. The dual band routers on the other hand have 2 radio chips....well most do some cheap ones don't.

In theory they could make a adapter with 2 radios and then they could use port bonding to combine them but they don't. Then again if you have a PC with 2 ethernet cables you could hook both to the same router and these could also be bonded but no consumer grade router supports it and it depends on the PC and the OS if it does it. Not sure why nobody supports this. But since it is not supported nobody sells wifi adapters with 2 radios. I would be nice even if you could connect to 2 different routers one on 2.4 and one on 5g but there must not be enough people that want these for vendors to sell them