Today’s wireless communications devices are not your father’s
car phone of yesterday. Mobile telephones in the 1980s were big
and heavy. A phone’s weight was measured in pounds instead of
ounces. Those that were hand transportable were referred to as
“luggable.” They were limited to low resolution character display.
Cellular phones today are portable, hand-held devices
smaller in overall size than yesterday’s mobile phones. Personal
Digital Assistant (PDAs) are more closely related to a small
computer than a cellular phone. Some include a proprietary
radio frequency modem for wireless communications whereas
others simply connect to a cellular phone through a serial
cable, radio link, or infrared port.
Figure 1-4 is a picture of an older “portable,” large by today’s
standards. Yet the first portable or “luggable” device were many
times larger and heavier than today’s handhelds. One of the earliest
units was consisted of a full three-watt mobile like the ones
installed in car trunks, a phone handset almost the size of a
home phone and a twelve-pound nickel-cadmium battery. The
whole unit was mounted in a heavy-duty transportation briefcase
and tipped the scales at forty-five pounds!
Figure 1-5 shows several manufacturers’ wireless PDAs and
Pocket PCs while Figure 1-6 illustrates some manufacturers’
current models of handheld cellular phones.
Tomorrow will bring many new wireless devices that communicate
over commercial cellular or within their own
assigned frequency bands. An example might be a smart or
Internet appliance that communicates warranty information to
the manufacturer or requests service. This will all be done over
the Internet, with a message returned to the end user to notify
him that the appliance has reported a malfunction and will
require service or that a software upgrade was completed and
no further action needs to be taken.
No matter what the end application, two things are rather
clear:
1. Any information presented across the Internet to or from
wireless devices will be limited by network bandwidth and
the display capabilities of the terminal device. To the end
user, bandwidth is the quantity of information transmitted
per second. In the wireless world, this is limited by the size
and efficient use of spectrum. A wireless device will not
display all of the information that a traditional Web site
may contain. Either some type of filtering will be applied to
convert Web site content to a suitable size, or other user
interfaces will be developed—such as text-to-voice translation
or a dedicated wireless Web site.
2. The projected number of personal computers connected to
the Internet will be exceeded by the number of Webenabled handsets by about 2003, see Figure 1-7 (600 million
wireless Internet users: source Dataquest).