Bluetooth® Wireless Technology
One key reason for the incredible success of
Bluetooth® technology is the tremendous flexibility it provides developers.
Offering two radio options, Bluetooth technology provides developers with a
versatile set of full-stack, fit-for-purpose solutions to meet the
ever-expanding needs for wireless connectivity.
Whether a product streams high-quality audio
between a smartphone and speaker, transfers data between a tablet and medical
device, or sends messages between thousands of nodes in a building automation
solution, the Bluetooth Low Energy (LE) and Bluetooth Classic radios are
designed to meet the unique needs of developers worldwide.
From
<https://www.bluetooth.com/learn-about-bluetooth/tech-overview/>
Bluetooth® Classic
The Bluetooth Classic radio, also referred to as Bluetooth
Basic Rate/Enhanced Data Rate (BR/EDR), is a low power radio that streams data
over 79 channels in the 2.4GHz unlicensed industrial, scientific, and medical
(ISM) frequency band. Supporting point-to-point device communication, Bluetooth
Classic is mainly used to enable wireless
audio streaming and has become the standard radio protocol
behind wireless speakers, headphones, and in-car entertainment systems. The
Bluetooth Classic radio also enables data transfer applications, including
mobile printing.
Bluetooth® Low Energy (LE)
The Bluetooth Low Energy (LE) radio is designed for very low
power operation. Transmitting data over 40 channels in the 2.4GHz unlicensed
ISM frequency band, the Bluetooth LE radio provides developers a tremendous
amount of flexibility to build products that meet the unique connectivity
requirements of their market. Bluetooth LE supports multiple communication
topologies, expanding from point-to-point to broadcast and, most
recently, mesh,
enabling Bluetooth technology to support the creation of reliable,
large-scale device
networks. While initially known for its device communications
capabilities, Bluetooth LE is now also widely used as a device positioning
technology to address the increasing demand for high accuracy indoor location
services. Initially supporting simple presence and proximity capabilities,
Bluetooth LE now supports Bluetooth® Direction
Finding and soon, high-accuracy distance measurement.
|
|
Bluetooth Low Energy (LE) |
Bluetooth Classic |
|
Frequency Band |
2.4GHz ISM Band (2.402 – 2.480 GHz Utilized) |
2.4GHz ISM Band (2.402 – 2.480 GHz Utilized) |
|
Channels |
40 channels with 2 MHz spacing (3 advertising channels/37 data channels) |
79 channels with 1 MHz spacing |
|
Channel Usage |
Frequency-Hopping Spread Spectrum (FHSS) |
Frequency-Hopping Spread Spectrum (FHSS) |
|
Modulation |
GFSK |
GFSK, π/4 DQPSK, 8DPSK |
|
Data Rate |
LE 2M PHY: 2 Mb/s LE 1M PHY: 1 Mb/s LE Coded PHY (S=2): 500 Kb/s LE Coded PHY (S=8): 125 Kb/s |
EDR PHY (8DPSK): 3 Mb/s EDR PHY (π/4 DQPSK): 2 Mb/s BR PHY (GFSK): 1 Mb/s |
|
Tx Power* |
≤ 100 mW
(+20 dBm) |
≤ 100 mW
(+20 dBm) |
|
Rx Sensitivity |
LE 2M PHY: ≤-70 dBm LE 1M PHY: ≤-70 dBm LE Coded PHY (S=2): ≤-75 dBm LE Coded PHY (S=8): ≤-82 dBm |
≤-70 dBm |
|
Data Transports |
Asynchronous Connection-oriented Isochronous Connection-oriented Asynchronous Connectionless Synchronous Connectionless Isochronous Connectionless |
Asynchronous Connection-oriented Synchronous Connection-oriented |
|
Communication Topologies |
Point-to-Point (including piconet) Broadcast Mesh |
Point-to-Point (including piconet) |
|
Positioning Features |
Presence (Advertising) Proximity (RSSI) Direction (AoA/AoD) Distance (Coming) |
None |
* Devices shall not exceed the maximum allowed
transmit power levels set by the regulatory bodies that have jurisdiction over
the locales in which the device is to be sold or intended to operate.
Implementers should be aware that the maximum transmit power level permitted
under a given set of regulations might not be the same for all modulation
modes.
From
<https://www.bluetooth.com/learn-about-bluetooth/tech-overview/>
How does Bluetooth work?
November 5, 2007
We go straight to the
source and get Bluetooth executive director Michael Foley to wirelessly
transmit an answer to this query.
Bluetooth technology is a short-range wireless communications
technology to replace the cables connecting electronic devices, allowing a
person to have a phone conversation via a headset, use a wireless mouse and
synchronize information from a mobile phone to a PC, all using the same core
system.
The Bluetooth RF transceiver (or physical layer) operates in the
unlicensed ISM band centered at 2.4 gigahertz (the same range of frequencies
used by microwaves and Wi-Fi). The core system employs a frequency-hopping
transceiver to combat interference and fading.
Bluetooth devices are managed using an RF topology known as a
"star topology." A group of devices synchronized in this fashion
forms a piconet, which may contain one master and up to seven active slaves,
with additional slaves that are not actively participating in the network. (A
given device may also be part of one or more piconets, either as a master or as
a slave.) In a piconet, the physical radio channel is shared by a group of
devices that are synchronized to a common clock and frequency-hopping pattern,
with the master device providing the synchronization references.
Let's say the master device is your mobile phone. All of the
other devices in your piconet are known as slaves. This could include your
headset, GPS receiver, MP3 player, car stereo, and so on.
Devices in a piconet use a specific frequency-hopping pattern,
which is algorithmically determined by the master device. The basic hopping
pattern is a pseudorandom ordering of the 79 frequencies in the ISM band. The
hopping pattern may be adapted to exclude a portion of the frequencies that are
used by interfering devices. The adaptive hopping technique improves Bluetooth
technology's coexistence with static (nonhopping) ISM systems, such as Wi-Fi
networks, when these are located in the vicinity of a piconet.
The physical channel (or the wireless link) is subdivided into
time units known as slots. Data is transmitted between Bluetooth-enabled
devices in packets that are positioned in these slots. Frequency hopping takes
place between the transmission or reception of packets, so the packets that
make up one transmission may be sent over different frequencies within the ISM
band.
The physical channel is also used as a transport for one or more
logical links that support synchronous and asynchronous traffic as well as
broadcast traffic. Each type of link has a specific use. For instance,
synchronous traffic is used to carry hands-free audio data, while asynchronous
traffic may carry other forms of data that can withstand more variability in
the timing for delivery, such as printing a file or synchronizing your calendar
between your phone and computer.
One of the complexities often associated with wireless
technology is the process of connecting wireless devices. Users have become
accustomed to the process of connecting wired devices by plugging one end of a
cable into one device and the other end into the complementary device.
Bluetooth technology uses the principles of device
"inquiry" and "inquiry scan." Scanning devices listen in on
known frequencies for devices that are actively inquiring. When an inquiry is
received, the scanning device sends a response with the information needed for
the inquiring device to determine and display the nature of the device that has
recognized its signal.
Let's say you want to wirelessly print a picture from your
mobile phone to a nearby printer. In this case, you go to the picture on your
phone and select print as an option for sending that picture. The phone would
begin searching for devices in the area. The printer (the scanning device)
would respond to the inquiry and, as a result, would appear on the phone as an
available printing device. By responding, the printer is ready to accept the
connection. When you select the Bluetooth wireless printer, the printing
process kicks off by establishing connections at successively higher layers of
the Bluetooth protocol stack that, in this case, control the printing function.
Like any successful technology, all of this complexity goes on
without the user being aware of anything more than the task he or she is trying
to complete, like connecting devices and talking hands-free or listening to
high-quality stereo music on wireless headphones.
From
<https://www.scientificamerican.com/article/experts-how-does-bluetooth-work/>
What Bluetooth is, what it does, and how it works
Bluetooth is a short-range wireless
communication technology that allows
devices such as mobile phones, computers, and peripherals to transmit data or
voice wirelessly over a short distance. The purpose of Bluetooth is to replace
the cables that normally connect devices, while still keeping the communications
between them secure.
The "Bluetooth" name is taken from a 10th-century
Danish king named Harald Bluetooth, who was said to unite disparate, warring
regional factions. Like its namesake, Bluetooth technology brings together a
broad range of devices across many different industries through a unifying
communication standard.
Bluetooth Technology
Developed in 1994, Bluetooth was intended as a wireless
replacement for cables. It uses the same 2.4GHz frequency as some other
wireless technologies in the home or office, such as cordless phones and WiFi
routers. It creates a 10-meter (33-foot) radius wireless network, called
a personal
area network (PAN) or piconet, which can
network between two and eight devices. This short-range network allows you to
send a page to your printer in another room, for example, without having to run
an unsightly cable.
Bluetooth uses less power and costs less to implement than
Wi-Fi. Its lower power also makes it far less prone to suffering from
or causing interference with other wireless devices in the same 2.4GHz
radio band.
Bluetooth range and transmission speeds are typically
lower than Wi-Fi (the wireless local area network that you may have in
your home). Bluetooth v3.0 + HS — Bluetooth
high-speed technology — devices can deliver up to 24 Mbps of data, which is
faster than the 802.11b
WiFi standard, but slower than wireless-a or
wireless-g standards. As technology has evolved, however, Bluetooth speeds have
increased.
The Bluetooth 4.0 specification was officially adopted on July
6, 2010. Bluetooth version 4.0 features include low energy consumption,
low cost, multivendor interoperability, and enhanced range.
The hallmark feature enhancement to the Bluetooth 4.0 spec is
its lower power requirements; devices using Bluetooth v4.0 are optimized
for low battery operation and can run off of small coin-cell batteries, opening
up new opportunities for wireless technology. Instead of fearing that leaving
Bluetooth on will drain your cell phone's battery, for example, you can leave a
Bluetooth v4.0 mobile phone connected all the time to your other Bluetooth
accessories.
Connecting With Bluetooth
Many mobile devices have Bluetooth radios embedded in them. PCs
and some other devices that do not have built-in radios can be
Bluetooth-enabled by adding a Bluetooth dongle, for example.
The process of connecting two Bluetooth devices is called
"pairing." Generally, devices broadcast their presence to one
another, and the user selects the Bluetooth device they want to connect to when
its name or ID appears on their device. As Bluetooth-enabled devices
proliferate, it becomes important that you know when and to which device you're
connecting, so there may be a code to enter that helps ensure you're connecting
to the correct device.
This pairing process can vary depending on the devices involved.
For example, connecting a Bluetooth device to
your iPad can involve different steps
from those to pair a Bluetooth device to your car.
Bluetooth Limitations
There are some downsides to Bluetooth. The first is that it can
be a drain on battery power for mobile wireless devices like smartphones,
though as the technology (and battery technology) has improved, this problem is
less significant than it used to be.
Also, the range is fairly limited, usually extending only about
30 feet, and as with all wireless technologies, obstacles such as walls,
floors, or ceilings can reduce this range further.
The pairing process may also be difficult, often depending on
the devices involved, the manufacturers, and other factors that all can result
in frustration when attempting to connect.
How Secure Is Bluetooth?
Bluetooth is considered a reasonably secure wireless
technology when used with precautions. Connections are encrypted, preventing
casual eavesdropping from other devices nearby. Bluetooth devices also shift
radio frequencies often while paired, which prevents an easy invasion.
Devices also offer a variety of settings that allow the user to
limit Bluetooth connections. The device-level security of "trusting"
a Bluetooth device restricts connections to only that specific device. With
service-level security settings, you can also restrict the kinds of activities
your device is permitted to engage in while on a Bluetooth connection.
As with any wireless technology, however, there is always some
security risk involved. Hackers have devised a variety of malicious attacks
that use Bluetooth networking. For example, "bluesnarfing" refers to
a hacker gaining authorized access to information on a device through Bluetooth;
"bluebugging" is when an attacker takes over your mobile phone and
all its functions.
For the average person, Bluetooth doesn't present a grave
security risk when used with safety in mind (e.g., not connecting to unknown
Bluetooth devices). For maximum security, while in public and not using
Bluetooth, you can disable it completely.
From
<https://www.lifewire.com/what-is-bluetooth-2377412>
What are some security concerns?
Depending upon how it is configured, Bluetooth technology
can be fairly secure. You can take advantage of its use of key authentication
and encryption. Unfortunately, many Bluetooth devices rely on short numeric
personal identification numbers (PINs) instead of more secure passwords or
passphrases.
If someone can "discover" your Bluetooth device,
he or she may be able to send you unsolicited messages or abuse your Bluetooth
service, which could cause you to be charged extra fees. Worse, an attacker may
be able to find a way to access or corrupt your data. One example of this type
of activity is "bluesnarfing," which refers to attackers using a
Bluetooth connection to steal information off of your Bluetooth device. Also,
viruses or other malicious code can take advantage of Bluetooth technology to
infect other devices. If you are infected, your data may be corrupted,
compromised, stolen, or lost. You should also be aware of attempts to convince
you to send information to someone you do not trust over a Bluetooth
connection.
How can you protect yourself?
·
Disable Bluetooth when you are not
using it. Unless you are actively
transferring information from one device to another, disable the technology to
prevent unauthorized people from accessing it.
·
Use Bluetooth in "hidden"
mode. When Bluetooth is enabled, make sure
it is "hidden," not "discoverable." The hidden mode
prevents other Bluetooth devices from recognizing your device. This does not
prevent you from using your Bluetooth devices together. You can "pair"
devices so that they can find each other even if they are in hidden mode.
Although the devices (for example, a mobile phone and a headset) will need to
be in discoverable mode to initially locate each other, once they are
"paired," they will always recognize each other without needing to
rediscover the connection.
·
Be careful where you use
Bluetooth. Be aware of your environment when
pairing devices or operating in discoverable mode. For example, if you are in a
public wireless "hotspot," there is a greater risk that someone else
may be able to intercept the connection (see Securing Wireless Networks for more information) than if you are in your home or your
car.
·
Evaluate your security
settings. Most devices offer a variety of
features that you can tailor to meet your needs and requirements. However,
enabling certain features may leave you more vulnerable to being attacked, so
disable any unnecessary features or Bluetooth connections. Examine your
settings, particularly the security settings, and select options that meet your
needs without putting you at increased risk. Make sure that all of your
Bluetooth connections are configured to require a secure connection.
·
Take advantage of security
options. Learn what security options your
Bluetooth device offers, and take advantage of features like authentication and
encryption.
From <https://us-cert.cisa.gov/ncas/tips/ST05-015>
History of Bluetooth
WLAN technology enables
device connectivity to infrastructure based services through a wireless carrier
provider. The need for personal devices to communicate wirelessly with one
another without an established infrastructure has led to the emergence
of Personal Area Networks (PANs).
·
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 May 1988, Companies
such as IBM, Intel, Nokia and Toshiba joined Ericsson to form the Bluetooth
Special Interest Group (SIG) whose aim was to develop a defacto standard for
PANs.
·
IEEE has approved a
Bluetooth based standard named IEEE 802.15.1 for Wireless Personal Area
Networks (WPANs). IEEE standard covers MAC and Physical layer applications.
Bluetooth specification
details the entire protocol stack. Bluetooth employs Radio Frequency (RF) for
communication. It makes use of frequency modulation to generate radio
waves in the ISM band.
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 ten 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.
For all discussed seminar topics list click here Index.
…till next post, bye-bye and take care.
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