68 Part I • Information Technology
Microwavehas been in widespread use for long-
distance wireless communication for several decades.
Microwave is line-of-sight transmission—there must be an
unobstructed straight line between the microwave trans-
mitter and the receiver. Because of the curvature of the
earth, microwave towers have to be built, typically about
25 to 50 miles apart, to relay signals over long distances
from the originating transmitter to the final receiver. These
requirements for towers, transmitters, and receivers suggest
that microwave transmission is expensive, and it is, but
long-distance microwave is less expensive than burying
fiber-optic cable in a very long trench, particularly if the
right of way for that trench has to be obtained. Microwave
is widely used for long-distance telephone communication
and, to a lesser extent, for corporate voice and data net-
works; transmission speeds up to 1 gbps are possible.
Other line-of-sight transmission methods exist in
addition to microwave. For short distances (e.g., from one
building to another), laser or infrared transmitters and
receivers, mounted on the rooftops, are often an economical
and easy way to transmit data.SATELLITE A special variation of wireless transmission
employs satellite communicationto relay signals over
very long distances. A communications satellite is simply
a big microwave repeater in the sky; it contains one orBluetooth is Here!
Harald Bluetooth was a tenth-century Viking king in Denmark. Now a wireless technology named in his
honor allows communication among a wide variety of devices, such as mobile telephones, desktop and
notebook computers, palmtop computers, DVD players, and printers, eliminating cables and permitting
communication where it used to be impossible. Bluetoothis short-range radio technology that has been
built into a microchip, enabling data to be transmitted wirelessly at speeds up to 3 mbps (Version 2.1 +
EDR)—and eventually at speeds up to 24 mbps if a Wi-Fi (wireless fidelity) connection is available
(Version 3.0 + HS). The Bluetooth Special Interest Group’s founding members were two leading mobile
phone manufacturers, Ericsson (Sweden)^1 and Nokia (Finland); two leading notebook computer
vendors, IBM (now Lenovo, based in China) and Toshiba (Japan); and Intel, the leading producer of
microprocessor chips. They have been joined by many other companies, including Microsoft and
Motorola, as promoter members. The Bluetooth Special Interest Group has developed Bluetooth
technology standards that are available free of royalties to any company that wishes to use them.
Products using Bluetooth technology have to pass interoperability testing prior to release. Thousands of
Bluetooth products of all kinds are now available for purchase, and Bluetooth support is embedded in
operating systems such as Microsoft Windows and Apple Computer’s Mac OS.
The possibilities are endless for the use of Bluetooth. By adding Bluetooth cards (containing the
microchip) to a notebook computer and a palmtop, a business traveler is able to synchronize the data in
a notebook computer and palmtop simply by placing both devices in the same room. Bluetooth can
eliminate the need to use cables to connect the mouse, keyboard, and printer to a desktop computer.
With several states now prohibiting driving while talking on a handheld phone, there is growing
demand for Bluetooth-equipped cell phones and hands-free headsets. An array of Bluetooth-equipped
appliances, such as a television set, a stove, a thermostat, and a home computer, can be controlled from
a cell phone—all from a remote location, if desired. The Bluetooth Special Interest Group has designed
the microchips to include software controls and identity coding to ensure that only those units preset by
their owners can communicate.
As a specific example, UPS is using Bluetooth technology in the ring scanners used by package
loaders. These ring scanners read bar-code data on packages and transfer it via Bluetooth to terminals
they wear on their waists. Then, using wireless LAN access points deployed throughout all of UPS’s
buildings, the data are sent from the LAN via a landline to a global scanning system—which stores all of
the information on packages—at one of two UPS data centers. Watch out for the Viking king—
Bluetooth is here!
[Based on Bluetooth Web site, 2010; Malykhina, 2006; Perez, 2009a; and Wildstrom, 2008](^1) The companies listed in this chapter have their headquarters in the United States unless otherwise noted.