Wireless
12
Bluetooth
Bluetooth devices can communicate without wires, using frequency-hopping spread spectrum (FHSS)
radio frequency (RF) to transmit and receive data in the 2.4 GHz Industry Scientific and Medical (ISM)
band (802.15.1). Bluetooth wireless technology is specifically designed for short-range (10 m (32.8 ft))
communication and low power consumption.
Devices with Bluetooth capabilities can exchange information (for example, files, appointments, and tasks)
with other Bluetooth enabled devices such as printers, access points, and other mobile devices.
The device supports Bluetooth Low Energy. Bluetooth Low Energy is targeted at applications in the
healthcare, fitness, security, and home entertainment industries. It provides reduced power consumption
and cost while maintaining standard Bluetooth range.
Adaptive Frequency Hopping
Adaptive Frequency Hopping (AFH) is a method of avoiding fixed frequency interferers, and can be used
with Bluetooth voice. All devices in the piconet (Bluetooth network) must be AFH-capable in order for AFH
to work. There is no AFH when connecting and discovering devices. Avoid making Bluetooth connections
and discoveries during critical 802.11b communications. AFH for Bluetooth consists of four main sections:
• Channel Classification - A method of detecting an interference on a channel-by-channel basis, or
pre-defined channel mask.
• Link Management - Coordinates and distributes the AFH information to the rest of the Bluetooth
network.
• Hop Sequence Modification - Avoids interference by selectively reducing the number of hopping
channels.
• Channel Maintenance - A method for periodically re-evaluating the channels.
When AFH is enabled, the Bluetooth radio “hops around” (instead of through) the 802.11b high-rate
channels. AFH coexistence allows enterprise devices to operate in any infrastructure.
The Bluetooth radio in this device operates as a Class 2 device power class. The maximum output power
is 2.5 mW and the expected range is 10 m (32.8 ft). A definition of ranges based on power class is difficult
to obtain due to power and device differences, and whether in open space or closed office space.
NOTE: It is not recommended to perform Bluetooth wireless technology inquiry when high rate 802.11b
operation is required.
Security
The current Bluetooth specification defines security at the link level. Application-level security is not
specified. This allows application developers to define security mechanisms tailored to their specific need.
Link-level security occurs between devices, not users, while application-level security can be implemented
on a per-user basis. The Bluetooth specification defines security algorithms and procedures required to
authenticate devices, and if needed, encrypt the data flowing on the link between the devices. Device
authentication is a mandatory feature of Bluetooth while link encryption is optional.
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