IPVMU Certified | 03/11/13 10:18pm
You are asking for pain if your intent is to use open spectrum wireless. Mobile hotspots have brought down the Wifi networks of many an Apple/Microsoft/Google convention. Licensing spectrum could eliminate this issue by ensuring no-one else is using the same frequencies, but it's likely to add cost to your installation.
Best way to find out is to run a site survey while a game is in progress. Then you'll get to see the spectrum and find out where the problems may lie.
James is right, open spectrum is completely out. Other frequencies could be used, but harmonics need to be factored in as well. I would not be surprised if it's not the wireless devices brought by spectators, but the high-intensity discharge lighting that actually causes the biggest problems.
Again, site survey is truly the only way to know.
IPVMU Certified | 03/12/13 12:27pm
900 MHz is out. There is only room for about 100mbps of traffic in that whole band. That is unlikely to offer enough bandwidth to cover an entire stadium.
I don't think 5ghz is a good idea either. Sure, directional antennas would help, but there is going to be crazy amounts of noise being generated.
Revisiting the original question: Yes, it is probably better to avoid wireless where possible in this situation.
IPVMU Certified | 03/12/13 02:20pm
"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.
IPVMU Certified | 03/12/13 06:48pm
The original question does not specify scope. If it is for a small enough camera count open spectrum could be made to work, but you are introducing risks that could be avoided, "Stadium" covers a pretty wide range of venues. But once you get to ones that seat "thousands of fans on gameday", ownership probably has sufficeint budgets and is concerned enough with ensuring reliability that they would ellect to pay for a frequency license or hardwire everything.