"Several" is far different than a stadiums worth. Your options with 900MHz (using Ubiquiti products) are:
- 1x 20MHz wide channels (100Mbps) - Problem here is you need to use an omni antenna (or possibly a very wide sector - but you would still need it to cover the whole stadium). You agreed that is a bad idea. Even if we took your minimum estimate of 3Mbps, assumed the wireless link performed optimally, and crammed it as full as possible (none of which I would recommend), we can only use 33 cameras. I count more cameras than that between my parking spot and the front gate of Tiger Stadium.
- 2x 10MHz wide channels (40Mbps each - 80Mbps total)
- 4x 5MHz wide channels (20Mbps each - 80Mbps total) - These two options allow the base station higher gain antennas, but we are giving up 20 percent of our total bandwidth.
Some other vendor besides Ubiquiti may be squeezing more out of that band, but not by much.
This is all besides the point. If you are setting up wireless anywhere in the license free spectrum, it is open to interference that is unpredictable and potentially unfixable (anyone can decide to use interfering channels and mess you up without asking permission). 5GHz certainly has more channels to exploit than 900MHz, but they are by no means unlimited. Even if we did a thorough sight survey at 5GHz now, there is no telling how crowded the 5GHz spectrum will be even five years down the road. Mobile devices have just begun to include 5GHz wifi radios.
Don't get me wrong, we deploy lots of cameras using wireless links in both the 2.4GHz and 5GHz spectrum (even a few at 900MHz, but that is rarer for us). Wireless is a viable solution in many situations. It is the nature of the venue that makes me very apprehensive.