Radio-link reliability

Hi all,

I am working on a large point to multipoint network. And I'm trying to calculate system availability... What I need are real figures about failure intensity on installation part, like connectors, antennas, cables, etc. Any idea where can I find it?
Another question: any typical figures about MTBF on propagation part of a ratio-link? Please suppose a correct designed link budget on 900 Mhz.

Regards
GIL