Bluetooth
● Bluetooth is a Wireless Personal Area Network (WPAN) technology and is used for
exchanging data over smaller distances.
● Bluetooth wireless technology is a short range communications technology
intended to replace the cables connecting portable unit and maintaining high levels
of security.
● Bluetooth technology is based on Ad-hoc technology also known as Ad-hoc Pico
nets, which is a local area network with a very limited coverage.
● They use short-wavelength, ultra-high frequency (UHF) radio waves within the range
2.400 to 2.485 GHz, instead of RS-232 data cables of wired PANs.

● Maximum devices that can be connected 2 to 8 devices.
● Bluetooth ranges upto 10 meters.
● It provides data rates upto 1 Mbps or 3 Mbps even more depending upon the
version.
● The spreading technique which it uses is FHSS (Frequency hopping spread
spectrum)

History of Bluetooth
The Bluetooth wireless technology was named after a Danish King named
Harald Blatand. His last name means "Bluetooth" in English.
The name "Bluetooth" was awarded to this technology because the Danish
King named Harald Blatand was united the Denmark and Norway, same
as Bluetooth wireless technology is used to unite two disparate
devices for communication or data transmission.

❏ Ericsson's Bluetooth project in 1994 defines the standard for PANs to enable
communication between mobile phones using low power and low cost radio interfaces.
❏ In 1998, four big companies of that time named Ericsson, IBM, Nokia and Toshiba
formed the Bluetooth Special Interest Group (SIG), which published the 1st version of
Bluetooth technology in 1999 whose aim was to develop a defacto standard for PANs.
❏ After that, four versions have been released.
❏ The latest version of this technology is Bluetooth 5.2.
❏ IEEE has approved a Bluetooth based standard named IEEE 802.15.1 for Wireless
Personal Area Networks (WPANs).

● Bluetooth employs Radio Frequency (RF) for communication. It makes use of
frequency modulation to generate radio waves in the ISM band.
Note :The ISM radio bands are portions of the radio spectrum reserved internationally
for industrial, scientific and medical (ISM)

The usage of Bluetooth has widely increased for its special features.
● Bluetooth offers a uniform structure for a wide range of devices to connect and
communicate with each other.
● Bluetooth technology has achieved global acceptance such that any Bluetooth enabled
device, almost everywhere in the world, can be connected with Bluetooth enabled
devices.
● Low power consumption of Bluetooth technology and an offered range of up to forty
meters has paved the way for several usage models.
● Bluetooth offers interactive conference by establishing an adhoc network of laptops.
● Bluetooth usage model includes cordless computer, intercom, cordless phone and
mobile phones.

There are two types of Bluetooth networks −
● Piconets
● Scatternets
Piconets
● Piconets are small Bluetooth networks, formed by at most 8 stations, one of
which is the master node and the rest slave nodes (maximum of 7 slaves).
● Master node is the primary station that manages the small network.
● The slave stations are secondary stations that are synchronized with the
primary station.
Types of Bluetooth

How Bluetooth Works:
Following is a list of some conditions that must be satisfied for a successful data transmission in Bluetooth
technology:
● Maximum number of Master Node - 1
● Maximum number of Slave Nodes - 7
● Maximum number of Nodes in a Piconet - 8
● Maximum number of devices that can be paired - 28
- 1 = 255
● Number of devices that can be parked → Infinite (∞)

● Communication can take place between a master node and a slave node in either
one-to-one or one-to-many manner.
● No direct communication takes place between slaves.
● Each station, whether master or slave, is associated with a 48-bit fixed device
address.
● Besides the seven active slaves, there can be up to 255 numbers of parked
nodes.These are in a low power state for energy conservation. The only work that
they can do is respond to a beacon frame for activation from the master node.
Piconets cont...

Scatternet
● A scatternet is an interconnected collection of two or more piconets.
● They are formed when a node in a piconet, whether a master or a slave, acts
as a slave in another piconet.
● This node is called the bridge between the two piconets, which connects the
individual piconets to form the scatternet.

Advantages
● Low cost.
● Easy to use.
● It can also penetrate through walls.
● It creates an adhoc connection immediately without any wires.
● It is used for voice and data transfer.

Disadvantages
● It can be hacked and hence, less secure.
● It has slow data transfer rate
● It has small range

Bluetooth Protocol Architecture

Bluetooth Radio : Specifics details of the air interface,
including frequency, frequency hopping, modulation scheme,
and transmission power.
Baseband: Concerned with connection establishment within a
piconet, addressing, packet format, timing and power control.
Link manager protocol (LMP): Establishes the link setup
between Bluetooth devices and manages ongoing links, including
security aspects (e.g. authentication and encryption).

Logical link control and adaptation protocol (L2CAP): Adapts
upper layer protocols to the baseband layer. Provides both
connectionless and connection-oriented services.
Service discovery protocol (SDP): Handles device information,
services, and queries for service characteristics between two or more
Bluetooth devices.
Host Controller Interface (HCI): provides an interface method for
accessing the Bluetooth hardware capabilities. It contains a command
interface, which acts between the Baseband controller and link
manager .

TCS BIN (Telephony Control Service): bit-oriented protocol that defines the
call control signaling for the establishment of voice and data calls between
Bluetooth devices.
OBEX(OBject EXchange) : Session-layer protocol for the exchange of
objects, providing a model for object and operation representation
RFCOMM: a reliable transport protocol, which provides a it provides a serial
interface with WAP.
WAE/WAP: Bluetooth incorporates the wireless application environment and
the wireless application protocol into its architecture.

Adopted Protocols − These are the protocols that are adopted from
standard models. The commonly adopted protocols used in Bluetooth
are
Point-to-Point Protocol (PPP)- Forward the IP Packets
Internet Protocol (IP) - Datagram Delivery(Router)
User Datagram Protocol (UDP) -
Transmission Control Protocol (TCP) and
Wireless Application Protocol (WAP).
Applications Layer − This includes the application profiles that allow
the user to interact with the Bluetooth applications.

• ISM band ranges between 2.400 GHZ to 2.483 GHZ.
•Bluetooth Wireless Technology enabled devices uses a technique called
FREQUENCY HOPPING .
•Data is divided into small pieces called Packets.
Transmitter and Receiver exchange a data packet at one frequency to
exchange, and then they hop to another frequency to exchange another
packet.
•They repeat this process until all the data is transmitted.

BWT devices randomly hop between frequencies up to 1600
times per second, much faster than other types of devices
that use the ISM band.