Cellular Digital Packet Data (CDPD ) is a data transfer protocol used, as a rule, in AMPS standard mobile phones. The speed could reach 19.2 kbit / s. Maintenance was discontinued due to the obsolescence of AMPS, 1xRTT , EV-DO and UMTS / HSPA replaced CDPD.
CPDP was developed in the early 1990s. However, it was difficult for him to compete with the existing slower, but cheaper Mobitex and DataTAC , and was not widely adopted to newer, faster standards such as GPRS .
CDPD had very limited consumer products. AT&T Wireless was the first to sell technology in the United States under the PocketNet brand. It was one of the first wireless web service products. Digital Ocean, Inc., an OEM licensed Apple Newton , sold Seahorse, which integrated the Newton PDA, AMPS / CDPD phones, and modem with a web browser in 1996. A company called OmniSky provided services for Palm V devices. Cingular Wireless later sold CDPDs under the Wireless Internet brand (not to be confused with Wireless Internet Express, a brand for GPRS / EDGE ). PocketNet was generally considered insufficiently competitive in the 2G services sector, unlike Sprint’s wireless network. AT&T Wireless sold four PocketNet phones: two AMPS / CDPD PocketNet standard models ( Samsung Duette and Mitsubishi MobileAccess-120 ) and two IS-136 / CDPD models ( Mitsubishi T-250 and Ericsson R289LX ).
Despite limited success among private clients, CDPD has been adopted in a number of corporate and government networks. CDPD was especially popular as the first generation to solve data transmission problems for telemetry devices and mobile data terminals.
In 2004, the closure of the CDPD service was announced. In July 2005, the AT&T Wireless and Cingular Wireles CDPD networks were closed.
CDPD Network
The main elements of the CDPD network are:
- End system : physical and logical end systems that exchange information.
- Intermediate systems : CDPD infrastructure elements that store, send and distribute information.
There are 2 types of end systems:
- The ultimate mobile system : a subscriber device for accessing the CDPD network via a wireless interface.
- Fixed end system : usually a host / server connected to a CDPD backbone network and provides access to a specific application and data.
There are 2 types of intermediate systems:
- Common intermediate system : a simple router without knowledge of mobility issues
- Intermediate mobile data system : a specialized intermediate system that routes data based on knowledge of the current location of the final mobile system. This is a set of hardware and software functions that provide registration, billing, authentication, encryption and so on.