Читать книгу Mobile Communications Systems Development - Rajib Taid - Страница 91

In the preceding sections, we have discussed the CN interfaces of GSM, GPRS, UMTS, LTE/EPS, and 5G networks. The logical interfaces between the respective RAN and its CN element are as follows:

 S1, between LTE eNodeB and MME; NG between 5G NR NG‐RAN and AMF

 Iu, between UMTS/UTRAN RNC and MSC; RNC and SGSN

 A, between GSM BSC and MSC

 Gb, between GSM BSC and SGSN

Over a particular logical interface, as mentioned above, the following types of signaling messages are exchanged in the forms of an AP between the RAN and CN for the execution of

 Interface‐specific protocol functions and procedures

 Session Management, Call Management, and MM air interface Layer 3 or NAS layer messages between a UE/MS and the CN, transparently through the RAN.

The AP functions and signaling procedures executed over the respective logical interfaces are specific to a particular mobile communications system and network. There are also protocol and signaling procedures that are similar in nature, but they are implementations dependent on a particular communications system.