Cisco sell a Wireless LAN controller, which can send disconnect packets to "rogue" APs that get set up, rendering them useless. This is particularly important at events where the airspace is severely cramped, such as big arena events, racing, horse racing etc. where the myriad of APs to provide coverage of free wifi to pundits would have to compete with these other APs. In a severely crammed airspace, this would help to encourage the other AP providers to turn their boxes off.<p>And getting a mobile telephone call in such events is even trickier, given that 50,000 people are in one space and the masts to serve them are oversubscribed. If they all suddenly want to place bets or browse the web, that's incredibly difficult to provide on the mast, so providers will set up additional masts for big events (like the big horse-racing events here in the UK). That's why they provide free wifi too, and having other APs set up and attempting to provide wifi over the airspace doesn't really help.<p>I wonder if Marriott hotels have the same approach in order to provide better wifi coverage? I have been in numerous hotels where the wifi coverage was great if you're sat in the bar but abysmal if you're down the other end of the building (where the hotels here in the UK are large old buildings with thick walls, very tricky for wifi).<p>Irritating if you're trying to use your phone to provide wifi to your laptop in order SSH to your own box at home or to get content via your mobile (which might be faster than their Internet access in some cases). I suppose you could just use a Bluetooth PAN instead (and it uses less power!)