Although a traditional classification, this
way of categorizing wireless technologies also includes
their differences in cost models, bandwidth, coverage
areas, etc. Finally, a section is included on issues related
to wireless technologies.
Voice and Messaging
Cell phones, pagers, and commercial two-way
business radios can provide voice and messaging services.
These devices may be based on analog or digital standards
that differ primarily in the way in which they process
signals and encode information. The analog standard is
the Advanced Mobile Phone Service (AMPS). Digital standards
are Global System for Mobile Communications (GSM), Time
Division Multiple Access (TDMA), or Code Division Multiple
Access (CDMA).
Normally, devices operate within networks that provide
metropolitan, statewide, or nationwide coverage. These
large and costly networks are operated by carriers such
as AT&T, Sprint, Verizon, local phone companies, etc.
and operate in different frequency bands which are allocated
by the FCC. Throughput depends on the standard being used,
but presently in the U.S., these networks operate throughput
rates up to 16 kilobits per second (Kbps). New digital
standards, also referred to as "Third-Generation
Services" or 3G, are expected by 2004, and will provide
30 times faster transfer rates and enhanced capabilities.
Because of the many standards, there are interoperability
issues between networks, carriers, and devices. Generally,
charges are based on per minute utilization or per number
of messages.
Hand-held and Internet-enabled devices
Internet-enabled cell phones and Personal Digital Assistants
(PDAs) have emerged as the newest products that can connect
to the Internet across a digital wireless network. New
protocols, such as Wireless Application Protocol (WAP),
and new languages, such as WML (Wireless Markup Language)
have been developed specifically for these devices to
connect to the Internet. However, the majority of current
Internet content is not optimized for these devices; presently,
only email, stock quotes, news, messages, and simple transaction-oriented
services are available. Other limitations include low
bandwidth (less than 14 Kbps), low quality of service,
high cost, the need for additional equipment, and high
utilization of devices' battery power. Nevertheless, this
type of wireless technology is growing rapidly with better
and more interoperable products.
Data Networking
We differentiate between pure data applications
in wireless local area networks (WLANs) and data, voice,
and video converged in broadband wireless. We also briefly
discuss Bluetooth, an emerging wireless technology.
