wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Bluetooth 49-5
49.2.5 Baseband Resource Manager
The baseband resource manager ensures access to the radio medium. For access to the channel, it runs
a scheduler to grant time to the negotiated entities by a contract. The other major function is to control
the contracts among entities. A contract means the guaranteed QoS contents delivery. The Bluetooth
behavior for such type of contracts management includes the normal exchange of data between connected
devices. It also manages the alignment between slots on the physical channel.
49.2.6 Link Controller
The link controller is responsible for the encoding and the decoding of Bluetooth packets from the data.
It also carries out link control protocol signaling that is used to communicate flow control, acknowledgement,
and retransmission request signals. The signal characteristics of logical transport is associated
with the baseband packet.
49.2.7 radio Frequency
The radio frequency (RF) block is responsible for transmitting and receiving data packets on the physical
channel. The baseband block controls the timing and the frequency carrier of the RF block, which is
between the baseband and the RF block.
Bluetooth works as a WLAN in the license-free ISM band at 2.4–2.4835.GHz, which is split up into 79
channels of 1.MHz bandwidths. There are some limitations for a few countries where only 23 channels
can be used. Bluetooth switches among 79 frequency channels 1600 times per second escaping possible
interferences very quickly. In its basic mode, the modulation is Gaussian frequency-shift keying (GFSK).
The raw wireless data rate is 1 and 3.Mbps supported for Version 2.x + EDR.
There are different device classes defined differentiating the maximum RF power output, and hence
the range (Table 49.1).
From specification 1.2, adaptive frequency hopping (AFH) was designed to reduce interference
between wireless technologies. It uses the available frequency in the spectrum. It is possible to choose
the unused frequency by detecting the used frequencies in the spectrum. This adaptive hopping allows
for a more efficient transmission within the spectrum, providing users with greater performance, even
if using other technologies along with Bluetooth technology.
The devices access the physical channel using assigned time slots. The consecutive time slots can be
assigned dynamically to the same device depending on the circumstances. It uses the full-duplex transmission
mode under the time-division duplex (TDD) mechanism.
49.2.8 Bluetooth Networks
49.2.8.1 Piconet
When Bluetooth devices establish connection between themselves and form an ad hoc network, this
personal area network (PAN) is known as a piconet. Each piconet can contain up to seven slaves and one
Table 49.1
Bluetooth Classes
Class Range Power Output (dBm)
Class 1 radios 100.m or 300.ft 20 (100.mW)
Class 2 radios 10.m or 33.ft 4 (4.mW)
Class 3 radios 1.m or 3.ft 0 (1.mW)
© 2011 by Taylor and Francis Group, LLC