Hello :-)!

Can you give me, please, names of protocols which may be useful for me?

In general I'd like to consider deeply PROTOCOLS, LAYERS and ROUTING connected with possibly reliable transmission of informations, especially through public network / telecommunication network and WiFi, WiMax. Not LAN, rather not virtual desktop.
I need it because I think about communication between railway devices - control (it involves safety) through ordinary public media. Information must arrive at time time "no longer than", cannot be disturbed and can't be accessed by unauthorized people. I thought about UMTS, however I would be grateful if you can suggest me other, alternative, ways :-).

Greetings :-)!