What are the components of a mobile network? What is the relationship between them?

There is no map here. I'll try to be more specific.

The whole mobile network is divided into core network part and wireless part. The wireless part is relatively simple, including base station transmitter BTS and base station controller BSC. The core network is divided into voice core network and data core network. In order to ensure high call quality, the voice core network has an independent backbone network and does not pass through the Internet. Its main parts are mobile switching center MSC, home location register HLR, short message center SMSC, intelligent network control node SCP and other network elements, and the relay transmission between them. At present, SS7 on E 1 is mainly transmitted, not TCP/IP on the Internet.

The flow from mobile phone to mobile phone is mainly as follows: MSa (calling mobile phone) initiates a call and goes to MSCa through BTSa and BSCa, and then MSCa goes to HLRb for location inquiry according to the called number, and then the call is routed to MSCb through the backbone network, then to BSCb and BTSb, and then the MSb (called mobile phone) is paged. After MSb responds, the call is established.

Of course, this is just a simple statement. If it is complicated, it is not too much to study for about a year, hehe.