CDPD

CDPD is the name for cellular wireless transmission using analog cellular.  Analog cellular is very similar to FM radio that we consumers use.  The largest differences are that analog cellular operates at a much higher frequency range (800 to 900 MHz), and that analog cellular mainly transmits voice and / or data rather than fm radio music.

As in the case of analog cellular, each data user of CDPD would be assigned a separate frequency - similar to FM radio - in order to keep their data separate from all other cellular analog conversations or data occurring at the same time.