Chapter 4 Using Bluetooth; Introduction; Adaptive Frequency Hopping - Motorola FR68 Series User Manual

Chapter 4 Using Bluetooth

Introduction

Bluetooth-equipped 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 (30 feet/10 meters) communication and low power consumption.
FR68 Series with Bluetooth capabilities can exchange information (e.g., files, appointments, and
tasks) with other Bluetooth enabled devices such as phones, and other mobile computers. To use the
FR68 Series as a modem, create a dial-up modem connection between a computer and FR68
Series.

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 Motorola mobile computers to operate in any infrastructure.
The Bluetooth radio in this FR68 Series operates as a Class 2 device power class. The maximum
output power is 2.5mW and the expected range is 32.8 feet (10 meters). A definition of ranges based
on power class is difficult to obtain due to power and device differences, and whether one measures
open space or closed office space.
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Using Bluetooth