M2M Communications in Industrial Environments

I have been investigating electromagnetic interference in industrial environments this week, we are trying to come up with a suitable solution for high speed wireless communications. To put the comms over an optical network would be the obvious solution, thereby getting no interference but optical is not very wireless, so I have been looking at Bluetooth which gives pretty good rejection but the data rates are not great, wifi is cheap and cheerful but gives a terrible ping for industrial comms. There is also 433Mhz and 2.4GHz to have a look at at least the kit for those is relatively cheap. Could do with a nice spectrum analyser – Have a good Easter