DGLewis
Member
Registered: Feb 2001
Location: Overland Park, USA
Posts: 15 |
CDMA / CDPD
Warkari observations are entirely sound.
CDPD is a packet switched digital datagram service built on top of the physical infrastructure and frequency bands of AMPS (the Advanced Mobile Phone System - the 1st generation cellular telephone technology (analog)).
It was added to the voice network systems after their implementation, and its design was constrained by the situation that no changes could be made these systems.
The technology was developed by IBM, which together with 9 operating companies formed the CDPD Forum to develop an open standard and multivendor environment for a packet-switched network using the AMPS systems.
The CDPD specification was completed in 1993 with key contributions from IBM, McCaw Cellular Communications, Inc., and Pacific Communications Sciences, Inc. Deployment of the 19.2-kbps CDPD infrastructure, designed to make use of idle channels in analog cellular systems, commenced in 1995.
CDMA is quite different; it is a set of a digital cellular technologies that uses spread-spectrum techniques.
There are now a number of variations of CDMA, in addition to the original Qualcomm-invented N-CDMA. For a more learned and extensive discussion of CDMA, past present and future, please read:-
http://www.comsoc.org/pubs/surveys/...sue/prasad.html
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