4G Network: 3.4. Integrity Control

I just received a message. How can I be sure that this message is coming from my network and not from someone else trying to send me false information or that this message hasn’t been modified by someone in the network?

4G Network: 3.3. Ciphering

Can someone beside me hear my communications and, especially, can he understand them?

4G Network: 3.2. Authentication

How can the network verify that a terminal that attaches gives its valid identity, in other words that the IMSI has not been modified ?

4G Network: 2.5. interfaces(S1, S5/S8, S6a, S11, X2)

What is the architecture of the 4G network? We have seen the principal elements, but we can ask ourselves if all these pieces are connected directly to each other. And, do all the pieces of equipment communicate with each other?