I'm interested to know what kind of network topology being deployed by telco for 3G/UMTS core network? If possible please provide some reference. Thank you very much.
it is star-like, but mostly mesh-like environment.
i m using word -like, as it not a pure mesh, not pure star, but a combination (i m telling by my experience, i don't have bookish reference)
Frequently there is a ring topology for prividing reliability. Besides there are hierarchical rings - many fiber optical SDH rings on the region layer which then connected to country layer optical ring. For example like this build transport network in Ukraine.