Overview

The purpose of this chapter is to provide the reader with a general, high-level concept of call controls (CC) and mobility management (MM) in wireless networks. Call controls are concerned with signaling procedures for establishing or releasing a call and sending miscellaneous messages (such as a status enquiry, status, information, congestion control, notifications, and so on) when a call is active. The term MM refers to location updates and location reporting as a mobile moves around from the coverage area of one radio network controller (RNC) to another or from one system (that is, a core network) to another and includes the registration of mobile stations (MS) and their authentication at appropriate instants. Authentication is the process by which the network validates the identity of a mobile subscriber. Whenever an MS performs a location update when relocating from the serving area of one mobile switching center (MSC) to another MSC or when it requests service, it may be required to go through the authentication process. ^[1] Some networks may also provide, on an optional basis, encryption of user data exchanged over the air interface, using a ciphering key that is derived during authentication.

To understand call control procedures, knowledge of signaling protocols is helpful. As such, we begin with a brief description of protocol stacks at reference points between an MS and a Base Transceiver Station (BTS), between a BTS and a MSC, and, for some systems, between an MSC/ Visitor Location...