TABLE OF CONTENTS For the typical mobile telecommunications network equipment vendor, ANSI-41 represents a collection of protocols for data communication protocols the vendor must implement to support the services associated with ANSI-41. In this chapter we identify the individual protocols included in ANSI-41, the functions of each, and how they collectively fit together. This structure is called the ANSI-41 protocol architecture.
The fundamental partition within the ANSI-41 protocol architecture lies between application services and data transfer services.
Application services make possible the transfer of information between application processes in the mobile telecommunications network. The nature of this application information its semantics and syntax, together with its movement between application processes defines the network s functions. For example, the basic call delivery function allowing a subscriber to receive calls when outside of the serving area of her or his home system would not be possible if the subscriber s identity and current location (i.e., application information) were not transferred from the visited system to the subscriber s home system.
On the other hand, from the perspective of the protocol entities providing the data transfer services, application information is nothing more than a collection of octets that must be moved from one node in the network to another. The octets could just as well correspond to a grocery list as a subscriber s location information; the blue collar job of data transfer would still have to be done.
Figure 8.1 illustrates this high-level view of the ANSI-41 protocol architecture as it applies to two ANSI-41 network...
