19-05-2012, 10:12 AM
Bluetooth wireless technology basics
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Abstract
This paper provides an overview of Bluetooth® wireless technology and instructs users on how to
establish Bluetooth connections using HP products. Bluetooth wireless technology is an inexpensive,
short-range radio technology that eliminates the need for proprietary cabling between devices such
as notebook PCs, handheld PCs, personal digital assistants (PDAs), cameras, and printers.
Introduction
Bluetooth wireless technology (BWT) was developed in 1994 at Ericsson in Sweden. The original
purpose of BWT was to eliminate the need for proprietary cable connections between devices such
as PDAs and notebook PCs. Although infrared communication existed at the time, it required line-ofsight
contact. Therefore, Ericsson chose to use an inexpensive, low-power radio built into each device,
making it possible to wirelessly connect devices through walls and other nonmetallic materials. After
Ericsson began work on BWT, the concept blossomed into a radio technology that simultaneously
connects several devices in a wireless personal area network (WPAN).
Because of the unlimited potential of BWT, the Bluetooth Special Interest Group (SIG)1 was formed
in 1998 to develop the Bluetooth Specification IEEE 802.15. The specification standardized the
development of BWT-enabled devices so that devices from different manufacturers can work together.
What does this mean for you? With BWT, you can run your presentation on a client's BWT-enabled
projector without a cable connection. If you leave a file on the desktop PC back at your office, don't
fret. Use your BWT-enabled PDA or laptop to connect to your office LAN via your BWT-enabled
mobile phone—without taking the phone out of your briefcase. Exchange electronic business cards
with everyone in the room, regardless of where they are sitting, with a few taps on your PDA. Then,
the PDA saves you time by automatically synchronizing their contact information with the email
application on your laptop. These BWT-enabled products are available today.
This paper provides an overview of BWT, describes the requirements for establishing a
BWT connection, and provides information about HP products that incorporate BWT.
How Bluetooth wireless technology works
BWT-enabled devices operate in the unrestricted 2.4-gigahertz (GHz) Industrial, Science,
Medical (ISM) band. The ISM band ranges between 2.400 GHz and 2.483 GHz. BWT-enabled
devices use seventy-nine 1-megahertz frequencies (from 2.402 to 2.480 GHz) in the ISM band
as shown in Figure 1. BWT-enabled devices use a technique called frequency hopping to minimize
eavesdropping and interference from other networks that use the ISM band. With frequency hopping,
the data is divided into small pieces called packets. The transmitter and receiver exchange a data
packet at one frequency, and then they hop to another frequency to exchange another packet. They
repeat this process until all the data is transmitted.
BWT devices randomly hop between frequencies up to 1600 times per second—much faster than
other types of devices that use the ISM band. This means that if another device, such as a 2.4-GHz
cordless phone, interferes with a BWT network at a particular frequency, the interference only lasts
for about 1/1600 of a second until the BWT devices hop to another frequency. This gives BWT
networks a high immunity to interference from other 2.4-GHz devices.
There are three classes of BWT radio devices, each with a different maximum range:
Class 1 (100 meters); Class 2 (50 meters); and Class 3 (10 meters). HP notebooks
feature Class 3 BWT radios, and HP printers feature Class 1 radios.
BWT security
BWT security is complex; yet, it is mostly transparent and easy for users to implement. BWT uses
three types of security mechanisms: authentication, authorization, and encryption. Authentication
verifies the identity of the BWT device trying to connect with your device. After authentication is
complete, your Bluetooth device grants (authorizes) another Bluetooth device access to a specific
service. Encryption translates data into a format that can be read by only another device with the
same encryption key.
The implementation of these mechanisms occurs at 3 levels (modes) of security:
• Mode 1—No security; anyone can use the device. This mode is the default setting for
public devices such as printers.
• Mode 2—In this mode, permission to access your device is dependent on the service(s) you
authorize (Service Level security). With your PDA, for example, you can allow another device
to exchange electronic business cards and deny the device access to contact information and
calendar entries.
• Mode 3—In this mode, the devices must be paired before they can establish a connection and
transfer data (Link Level security). For more information, see "Pairing" in the following section.
Establishing BWT connections
This section describes how to establish BWT connections using your notebook PC, iPAQ Pocket PC,
printer, and cellular phone. The first step is to activate BWT functionality on each device. Then, you
can select the services (profiles) that your device will make available to other BWT-enabled devices.
If you decide to operate your device in secure mode, you must pair the device with another
BWT-enabled device before they can interoperate. These requirements are explained below.
Activating BWT devices
Notebook PCs
If you are not sure whether your notebook supports BWT, check for the presence of Bluetooth
Devices in Device Manager as follows:
1. Select the Start button in the lower-left corner of the screen.
2. Then select Control Panel > Performance and Maintenance > System >
Hardware tab.
3. Select the Device Manager button.
4. If your notebook supports BWT, you will see Bluetooth Devices in the Device Manager
window (Figure 4).
Selecting BWT device profiles
Profiles are services that are available for each BWT-enabled device. When two BWT-enabled
devices are within range, they perform a service discovery during which they report a list of available
profiles. If any of the profiles for the two devices match, they can connect and interoperate based on
the matching profiles.
Table 2 describes some of the BWT profiles built into HP notebook PCs, iPAQ Pocket PCs, and
printers. Detailed instructions on performing the functions listed in this section are described in
the documentation that accompanies each HP product. To see the full line of HP BWT offerings
and to view product compatibility, visit http://www.hpproducts/wireless/PAN/. Also, visit
http://www.hpproducts/wireless/ for updates to the HP wireless product portfolio