How would you do... Mass wireless coverage for a conference?

A friend of mine has been asked as part of his job to provide wireless coverage for a conference going on where he works.

They're expecting around 400 guests, who will likely turning up with their own laptops that will need to be on line and they'll all be in the one, fairly large auditorium space.

Given he only has access to between 8 and 12 unmanaged 3Com b/g access points and next to no budget for extra kit, how would you set things up?

The same / different SSIDs for each AP?
Would you force APs to be 'b' or 'g' only?
How would you spread channel usage?
Which way would you point antennas (all the same way / perpendicular to the next-closest AP / randomly all over the place)?
Would you secure the wireless? Would you make assumptions about the level of security supported by guests' laptops (WEP!/WPA/WPA2)?

What other things aught to be considered? (Besides a router/firewall to separate guests from corporate network users, and the internet bandwidth problems you'd end up with on a slow-ish connection!)



Please bear in mind, I'm not involved with this at all. I just heard about what he's been asked to provide and it got me wondering how you'd actually approach the problem!

why limit to G usage? Why not have dual APs that can shunt out N as well as G?

That way the N users get on the N Bandwidth, and the G users get on the G bandwidth.

I would also use a system where there is likely to be little channel interference.

Xirrus could handle it all from 1 array, but you would be looking at a slow system because everyone on 54mbps would be sluggish at best
Meru would have the advantage where its single channel, so no interference, you would get different speed APs running the same SSID and it determines the best AP for the device (N or G)
Ruckus would be good for the zone flex system, not to mention that they are nice and high powered

@Net-Ctrl or @CPLTD could help you out I am sure if you need anything more :)

400 users using cheap b/g unmanaged access points? That just ain't gonna work properly.

Whichever way you try and do it in a big open space, you're going to get massive amounts of collisions.

For an average unmanaged AP, you'll get 15 people maximum working on it reliably. So, with your max number of 12, you'll get 180 people connected maximum. Ok, they'll just be browsing the internet, but the volume of users will get in the way of each other basically, and everyone will end up suffering due to it.

Your best bet is to get a company to sponsor the event and have them lend you a managed wireless system for the time its running. A handful of Ruckus APs and a controller would handle the load nicely IMO.

You'd get better speeds having 40 runners taking peoples web requests and running them to a computer, then printing the pages out and returning them :-p

Given that you must use existing equipment, here's how I would go about it:

The same / different SSIDs for each AP?

The same SSID.

Would you force APs to be 'b' or 'g' only?

This is an option on the access points themselves. It would be safe to set it to 'g' only these days.

How would you spread channel usage?

Use channels 1, 6 and 11. These do not overlap each other.

Which way would you point antennas (all the same way / perpendicular to the next-closest AP / randomly all over the place)?

It's difficult to say really, other than point in the direction your guests will be sitting.

Would you secure the wireless? Would you make assumptions about the level of security supported by guests' laptops (WEP!/WPA/WPA2)?

It depends what exactly is going over the wireless. As a recommendation, I probably would secure it using WPA AES. I still come across the odd machine now and again which needs updated drivers to support WPA2.

Of course the other thing to think about is a suitable DHCP server, such as a router.