Читать книгу Mobile Communications Systems Development - Rajib Taid - Страница 133

This chapter covers one of the most important functionalities, that is, interworking and interoperation, through which mobile communications networks provide seamless communications services to subscribers. Interworking facilitates an operator to provide various communication services to its subscribers within its home network. We begin with the basic interworking among the Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS), and Long‐Term Evolution (LTE)/Evolved Packet System (EPS) networks and show how it can be realized within a home network using upgraded/enhanced and legacy network elements. We then present the advanced interworking features through which an operator may provide voice call services to subscribers currently registered in an LTE/EPS network. Interworking between the LTE/EPS and the 5G system is also described briefly.

Interoperations facilitate the operators to provide various communications services to their roaming subscribers when traveling outside of the home network. Interoperation works through the interworking of networks of the same or different operators. We present the interoperation cases for roaming subscribers through a visiting network that deploys either upgraded/enhanced or legacy network elements. We then close this chapter with the methods of routing roaming user data to the external network.