# Forum

## WiFi on a crowded environment with 2.4Ghz

7 posts by 4 authors in: Forums > CWNA - Enterprise Wi-Fi Admin
Last Post: July 3, 2018:
• Hi there,

Is it possible to make WiFi work on a concert with 8000 people together, using 2.4Ghz?

It is allowed to use any AP brand and ilimited number of APs.

• You don't give nearly enough details.   But for the h--- of it, lets make some nonsensical computations:

8000 clients/3 channels = 2,667 clients per channel

Depending on the AP your using, you might get (say) 25 users/AP

2667/25 = 107 AP's

lets update that to 121 AP's for kicks.    Crammed into a small 11 x 11 matrix of AP's 30 feet apart would give you ((11+1) *30 ft) **2 = (360 ft x 360 ft) = 129,600 sq. ft coverage.

No matter how you slice it, that's pretty unreasonable - from several standpoints  !!!

Talk to somebody like Aerohive, iBwave., or another reputable company if your're really thinking of coming up with such a scheme.

PS:   I'm making no claims of reasonableness for any of my corny computations above.

• Thanks for the reply mate.

Sorry for being so brief.

The space is actually 51,666 sq.ft , and the maximum number of people is 8000, so let's say at least 35% concurrent users, 2.800 connections, seems fair?

I was thinking around 75 users per radio, on a 2 rádio AP/AC 3x3:3 MIMO. So let's say 2.800/3 = 933 clients per channel.

Also, I was thinking about minimize the radio output, to let's say 12dBm instead of the max 20. So we could install AP closer of each other. Does that make sense?

Today I have 12 AP's - Xirrus XR-630.. but it just gives me 500 concurrent users, after that too much interference and no one can connect anymore.

• @UAIFI  Why do you want to do this is 2.4GHz? On 5GHz you would have more channels, which means less users per channel, and shorter range.

I don't have personal experience with Xirrus products, but I have heard good about them. XR-630 appears to be an older model, but apparently you can use it's both radios for 5GHz (or 2.4GHz if you insist).

You don't specify what kind of a concert: seated or not. Anyways, you should get creative. How about placing the access points low? Put them under the seats or if there are no seats, under the floor. If it's outside, bury them in plastic boxes in the turf. If there are tables, stands, barriers, dividers place the APs there at or below knee level. Turn the transmit power down, too, perhaps below 10dBm. That way you have the humans absorb the signal, so you get smaller cell size. If you place a lot of APs close together above the crowd you'll just create cacophony.

Testing this for optimal transmit power and AP spacing will require a lot of volunteers. Put a poster at a nearby college offering free beer :o) Put the beer stands where you have the test area so you'll get a tight crowd around the APs. Run an open network for the test to get every device to associate. Run games on Kahoot.it to generate traffic. Like I said, be creative.

Report here how did it go and what you learned.

• Hi Petri,

But unfortunately we have to support 2.4Ghz because we are located in Brazil, and still most users have 2.4Ghz devices.

Its a "stand up" concert, indoors, currently the only place we can install the APs are on the ceiling.

With 12 APs we have already tried to lower the radios power output but withou success, I really don't have much hope that will work if we only add more APs, just because 2.4Ghz may be impossible to support on an environment like this.

I really aprecciate your help on this matter Petri! If you want to add me on skype -> lucasrussoal

Thank you!

• You still can run both 2,4 and 5GHz to get at least some users off the 2,4. Most systems support some kind of band steering.

If you are indoors there has to be walls by definition. You can still place some access points around the area at knee height. If you can swap the antennas for directional the better. If you are stuck on omnidirectional you can place dividers of reflecting (metal) or absorbing material between the access points. They don't have to large, just 30cm (12") wedges placed midpoint between the APs will improve things.

The numbers you mention could mean a 70x70 meter area. You can place access points around the perimeter at 10-15m intervals if you can direct them or use dividers. Keep the power low: 12dBm or 16mW is plenty.

Often there are electricity outlets or some other access holes in the floor. You can place access points there if you replace the cover with a wood or plastic cover. Usually the covers are metal plate.

The perimeter and mounted access points will get at least some clients off the overhead network. I didn't say the coverage will be good, but if you have to implement this, use these to improve the result.

Oh, and you still need beer for testing. Be the hero of the party!

Page 1 of 1
• 1