Wireless devices are not always cellular phones. In fact, they do
not even need voice capabilities. Does you home PC have a
telephone receiver hanging on it? Of course not: The computer’s
primary function is to do meaningful data crunching!
Personal digital assistants and pocket PCs were created to
provide a certain level of support for the mobile user, which
could only previously be available on a laptop PC, but smaller
and lighter. They are not primarily voice communications
devices—they are for storage, retrieval, and manipulation of
data. Some PDAs and pocket PCs may attach to a cellular
phone or other type of wireless modem, but only for the wireless
connectivity of data communications. At least one manufacturer’s
cellular phone has a PDA built-in. It is immaterial
whether we choose to call it a phone with PDA or a PDA with
a phone built into it.
There is an entire class of devices devoted to wireless
mobile data. Some PDAs are primarily email devices. Others
are more generic and can run many different applications, such
as the Palm Pilot or Visor. All, however, fall into two categories:
They either use public cellular for communications or they use
other public or private networks. They all share the same limitations
for data transmission, and they are limited to the current
state of the art of the physical access channel. Except for
Ricochet, this means 19.2 Kbps or less. When they are upgraded
to next-generation cellular, data rates will increase.
One very interesting thing to watch will be the migration or
upgrade paths for the noncellular networks when competition
for higher data rates begins. Most are using 19.2 Kbps for wireless
PDA and Pocket PC communications.