Chapter 4 Using Bluetooth; Introduction; Adaptive Frequency Hopping - Motorola FR6876 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.
FR6876s 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 FR6876 as a modem, create a
dial-up modem connection between a computer and FR6876.

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.
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