Editing Cellular digital packet data (section)

==CDPD Network and system==
Primary elements of a CDPD network are:
1. '''End systems''': physical & logical end systems that exchange information
2. '''Intermediate systems''': CDPD infrastructure elements that store, forward & route the information

There are 2 kinds of End systems
1. '''Mobile end system''': subscriber unit to access CDPD network over a wireless interface
2. '''Fixed end system''': common host/server that is connected to the CDPD backbone and providing access to specific application and data

There are 2 kinds of Intermediate systems
1. '''Generic intermediate system''': simple router with no knowledge of mobility issues
2. '''mobile data intermediate system''': specialized intermediate system that routes data based on its knowledge of the current location of Mobile end system. It is a set of hardware and software functions that provide switching, accounting, registration, authentication, encryption, and so on.

The design of CDPD was based on several design objectives that are often repeated in designing overlay networks or new networks. A lot of emphasis was laid on open architectures and reusing as much of the existing RF infrastructure as possible. The design goal of CDPD included location independence and independence fro{{Clarify|date=June 2016}}, service provider, so that coverage could be maximized; application transparency and multiprotocol support, interoperability between products from multiple vendors.