6
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I am need to setup wifi connection for an expected audience of 100 users connected via Laptops. I currently have 3 802.11 G routers, that are all designed for home usage such as the WRT54G APs. Google didn't really turn up anything helpful. And will the 54Mbits connection be shared among the number of connected users as well? Any tips and experience in setting up wifi for conferences would be great. Thanks.

Update: The clients will be a mix of a/b/g/n. Although we won't be supporting n. The internet pipe is a 8 Mbits and isn't that great. But there is an internal file sharing that part of the event as well other than internet. Instead of WRT54G, if there are other better options such as RouterStation or installing OpenWRT I am all ears. Tried out a priliminary test and it is like everyone has commented below. Trying to get even up to 10 client connected was not an easy chore.

Update2: DHCP will be handled by a Ubuntu Server.

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7 Answers 7

4
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See The “WiFi At Conferences” Problem by Joel Spolsky

and

Why is Internet access and Wi-Fi always so terrible at large tech conferences?

3
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Even with good enterprise grade Access Points like Cisco Aironet 1200's and with a managed environment (with WDS\WLSE etc infrastructure) you will struggle to sustain >10 active users per AP on 2.4Ghz. If you can use 5Ghz 802.11n\a then you may be able to hit 30 concurrent users and still get acceptable web browsing traffic. To set this sort of thing up properly you would need about 10 AP's with 2.4Ghz kit and you can not do that reliably without using a management system so you can be certain you are getting effective cell coverage and managing interference. Even if you do that the various 2.4Ghz client devices tend to misbehave a lot so if you cannot ensure a uniform set of clients you will struggle to get this to work consistently especially in an environment with a lot of warm wet human bodies moving around.

If you need to support 60 concurrent users in a reasonable space with 5Ghz WiFi standards things are a lot easier - there are (many) more non-overlapping channels available, the RF environment is much cleaner, the Client devices that support 5Ghz are generally much better behaved and you have that basic carrying capacity on each channel that is higher. You might be able to get away with just two but with 3 AP's it should work pretty well for 60 users provided none of them are doing unfriendly things like bit-torrenting or live-video streaming and you have an internet uplink that is fast enough - 100Mbps or so would be ideal.

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  • More than 10 active users per AP for a Aironet 1200? Out of curiosity, is this from experience, or a spec sheet? We run >20 active users/per WAP on our Aironet 1200s, and don't have issues. (?) Jan 21, 2010 at 22:01
  • From experience. Large scale deployments with 2.4Ghz, enterprise wide in a Fortune 10 company with at the time (>2 years ago now, perhaps they've improved but the issues were with the band we felt not the AP's), on 5Ghz channels things were dramatically better. In concentrated areas (conference rooms, canteens etc) or areas with ambient interference (proximity to factory floors) we had a lot of trouble with density. When average attach rates per AP passed 10 quality dropped significantly, not a major issue for basic web browsing\e-mail sync but fatal for conferencing\real time apps.
    – Helvick
    Jan 21, 2010 at 22:32
  • I see. Didn't catch the band, not the AP, issue in your answer. Thanks! Jan 22, 2010 at 0:03
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From personal experience, we had 2 of these for 80-odd people in a classroom, and they worked, but we had to reset them constantly--They are just built not for that type of use.

Josh

1
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Another question about using the WRT54G beyond its operational capability. You're lucky if you can get >10 clients to connect to it, and still have reasonable performance.

If you want really good wireless, you're going to have to pay for it. You'll want Cisco Aironet 1200 access points, maybe a WLAN controller too.

I'd say that you're probably going to need to fork out between 1000 and 3000 USD, ish, and that's before you start thinking about the fat pipe you're going to have to share.

I could spend ages architecting the Ideal Conference Wifi Solution, but I don't think the market is there for it.

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  • Yes. DHCP will not be handled by the routers but by a different server. Jan 22, 2010 at 17:59
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My experience with WRT54G devices is that you're not going to get more that 20 clients to associate with one. Over about 15 clients will be unusable anyway (the client will associate but won't traffic will flow poorly). I'd imagine that most consumer-grade devices will perform nearly the same way.

What's the Internet pipe at the venue like? You'll all be sharing that, too.

Do you expect your clients to be 802.11n capable? If so, you can get a lot more spectrum by using 802.11n capable access points.

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This is just a thought and I am not even sure its effectively doable or would solve the problem. Could you let a better-quality piece of equipment handle DHCP and pass that through the Linksys router?

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I found that once I had any kind of ACL or routing rule in place on a WRT54G that the processor limited me to approximately 12mbps of inspected traffic.

I suspect that this will become your problem before any issues that might arise with the 2.4 band.

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