Ask Slashdot: Overcoming Convention Hall Wi-Fi Interference?

bbowman writes "One of my job responsibilities is to set up the small network for our company's exhibit at the trade shows we attend. The mobile demo devices we use depend upon a reliable Wi-Fi connection to a router I have in the exhibit. In the days leading up to the opening of the trade show, W-iFi connections are reliable and work as expected. However, as soon as the show opens none of our devices can reliable maintain a Wi-Fi connection to the router. The devices we use at the trade shows are Windows-based laptops, iPods/iPads, Android tablets, and a variety of Wi-Fi enabled cell phones. I have tried using channels 1, 6, and 11 (as well as the others) and used different routers (Linksys, D-Link, Netgear) without success. I'm sure it is likely that there are poorly insulated electrical cabling, fluorescent lighting, and other issues that would contribute to Wi-Fi interference in the convention hall. A quick scan shows dozens and dozens of discoverable Wi-Fi networks nearby. If I take the router back to my hotel room, I have zero connection problems. How can I overcome this so that Wi-Fi works reliably in the convention hall?"

Get ye some 802.11a.

[FooAtWFU]

802.11a has a lot more spectrum. Aside from that, hoping that you can drown out everyone else's screaming really isn't going to work.

Alternatively, install a giant metal Faraday cage. (Good luck with that.)

A problem...

[fuzzyfuzzyfungus]

The problem is intrinsically a hard one, 802.11* wasn't really designed for a zillion flacks in a large room, each toting personal cell routers and whatnot.

However, it is possible that the problem could be solved by money. Let's just say that "(Linksys, D-Link, Netgear)" isn't exactly an honorable lineup of the finest names in Serious Wifi. Cheap, yes, quite delightfully so. Built right down to price? Well, you could say that...

You might want to do some looking into the world of "industrial wifi" products. The environmental resistance of such will be total overkill for a tradeshow floor; but (successful) offerings in that sector are designed for people who need their network to work despite the fact that it is in the middle of a factory floor or next to the arc welder or what have you.

The trouble with going upmarket, though, is that it can be somewhat hard to tell what is genuinely better at wireless networking vs. what is just the same old shit on the wireless side; but in a POE, ruggedized, -40/+135 thermal resistant, with baked-in proprietary management protocols in the firmware, container. You really want the former, not the latter...

Wrong assumptions

[mrmagos]

Given this:

In the days leading up to the opening of the trade show, W-iFi connections are reliable and work as expected. However, as soon as the show opens none of our devices can reliable maintain a Wi-Fi connection to the router.

I doubt it's this:

I'm sure it is likely that there are poorly insulated electrical cabling, fluorescent lighting, and other issues that would contribute to Wi-Fi interference in the convention hall.

...and more likely this:

A quick scan shows dozens and dozens of discoverable Wi-Fi networks nearby.

I would recommend trying a few things:
- Reduce your RTS threshold, if your AP supports it.
- Reduce the fragmentation threshold, if your AP supports it.
- Play with data rates, reducing them if your AP supports it.

If your AP does not support any of those options, go out and get a real AP.

Re:Wrong assumptions

[Anonymous Coward]

I'll go with Upgrade The Access Point...

Quoting a post to the SoCal FreeNet list on July 21, 2011 by Matt:

Just an interesting tidbit. I was asked to help out with the soccer game at Qualcomm Stadium last night. They had a special area on the field for the photographers and wanted to be able to have the photographers connected to the net to upload their pictures to their respective news agencies without leaving the field. Just off the tunnel that the players come out is the "media room" where we have just a little Netgear wireless router/access point for the photographers to use during Chargers games, so I just grabbed that, ran 280 ft of CAT-5 out to the field plunked down the Netgear, and set it to WPA2 encryption. I tested it thoroughly the day before the game. The next day, a few minutes after the game started, I got called down to the field because the wireless wasn't working. Everyone was associated with the SSID, but it wouldn't pass any traffic. So I power cycled it, and went back upstairs, and was called back down within minutes. With all the fans in attendance, many of them with wireless enabled smartphones, keeping track of all the wifi in the air must have been too much for the little Netgear, the thing couldn't pass traffic for more than 5 minutes between reboots.

So, plan B, went up to the media booths which weren't really being used for this game, and snagged a crusty old Cisco Aironet 1121B (yes, 802.11b) and put it in place of the Netgear on the field, even left it unsecured as I didn't have time to much about with it. Long story short, not a peep out of it the rest of the game.

I had been told many years ago, that what happens is the mac table of the cheaper wifi gear gets full trying to keep track of all the mac addresses it sees flying around the air, but I haven't confirmed this. Long story short, an old crusty Aironet is better than a fancy new consumer grade AP for large events any day of the year.

Re:Wrong assumptions

[sew3521]

The Netgear WNDR3700 is a great router especially when you put DD-WRT firmware on it. DD-WRT made a special firmware JUST for this router which has numerous advanced features. Because it uses the Atheros chipset you can also play with channel size, RTS threshold, etc.