Bluetooth Overview
Bluetooth and Wi-Fi
Bluetooth and Wi-Fi are often compared to each other because they are both capable of
providing networking on the 2.4GHz consumer frequency band. Many of the differences
between these two technologies can be traced to the fact that networking was not the primary
design goal for Bluetooth as it was for Wi-Fi. With a greater transmission range (about 100
meters indoors) and larger bandwidth (about 11Mbps), Wi-Fi is typically the better choice for
wireless LANs and Internet connectivity.
Bluetooth on the other hand was designed for driverless, cordless connectivity between
devices. Because Bluetooth transmitters are smaller in size, have lower power demands, a
more limited range (10 - 100 meters) and narrow bandwidth (1Mbps), they are better suited
for use in embedded and mobile devices that exchange smaller amounts of information while
conserving power and space.
While their functionality does not compete directly, 802.11b and Bluetooth do compete for the
airwaves. Since they both operate on the 2.4GHz band of the ISM radio spectrum, these two
wireless technologies may interfere with each other. Bluetooth devices minimize interference
by employing a frequency-hopping spread spectrum scheme that changes the frequency
used about 1600 times per second. Unfortunately, since Wi-Fi uses a direct sequence spread
spectrum method, this also means that Bluetooth transmissions will collide with those of any
nearby 802.11b devices and slow Wi-Fi data transmission rates. The Bluetooth SIG and its
member companies have put a lot of effort into coexistence solutions for these two standards
and are very committed to ensuring that these devices work well together.
While 802.11b was designed solely for data communications, Bluetooth takes things quite a
bit further. A key component of the Bluetooth standard is its notification and service discovery
mechanism. This allows Bluetooth devices to identify themselves and describe their
capabilities to other Bluetooth devices in the area. For instance, the Dial-Up Networking
profile defines how discoverability can be used to locate and connect to other devices such
as a cellular phone that supports the same profile. The profile then describes how to dial the
phone, connect to either analog or data services, and control the connection seamlessly. This
combination of dynamic discovery of services and built in definitions of the services goes well
beyond anything offered by the 802.11b protocol.
Security
Bluetooth security is defined by three main elements: availability, access, and confidentiality.
It is important to distinguish between these elements because Bluetooth security is also
highly configurable so that it can meet the needs of devices in many different scenarios. An
understanding of the basics will provide the knowledge that you need to choose a security
strategy for your device.
The first important element of Bluetooth security is availability. If a device cannot be seen or
connected with, it is obviously quite secure. Bluetooth defines both of these features as part
EmbeddedBlue 505 User Manual
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