Bluetooth Technology

What is Bluetooth : Architecture & Its Working

Well-established technology like Bluetooth is used to provide?wireless?connectivity from wireless headphones to mobile phones, laptops & mice of the wireless computer to a lot of other devices which need a short-range of connectivity. This technology has developed & expanded drastically to provide not only the fixed short-range audio streaming in the applications of M2M communications and mesh connectivity of IoT. This technology provides better flexibility, very fast speed & far more capability. This article discusses an overview of Bluetooth.

What is Bluetooth Technology?

Bluetooth technology is a high-speed low powered wireless technology link that is designed to connect phones or other portable equipment together. It is a specification (IEEE 802.15.1) for the use of low-power radio communications to link phones, computers, and other network devices over short distances without wires. Wireless signals transmitted with Bluetooth cover short distances, typically up to 30 feet (10 meters).

It is achieved by embedded low-cost transceivers into the devices. It supports the frequency band of 2.45GHz and can support upto 721KBps along with three voice channels. This frequency band has been set aside by international agreement for the use of industrial, scientific, and medical devices (ISM).rd-compatible with 1.0 devices.

It can connect up to “eight devices”?simultaneously and each device offers a unique 48-bit address from the IEEE 802 standard with the connections being made a point to point or multipoint.

History Of Bluetooth

Bluetooth wireless technology was named after a Danish Viking and King, Harald?Blatand; his last name means “Bluetooth” in English. He is credited with uniting Denmark and Norway, just as Bluetooth wireless technology is credited with uniting two disparate devices.

The Bluetooth technology emerged from the task undertaken by Ericsson Mobile Communications in 1994 to find an alternative to the use of cables for communication between mobile phones and other devices. In 1998, the companies Ericsson, IBM, Nokia, and Toshiba formed the Bluetooth Special Interest Group (SIG) which published the 1st?version in 1999.

The first version was 1.2 standard with a data rate speed of 1Mbps. The second version was 2.0+EDR with a data rate speed of 3Mbps. The third was 3.0+HS with a speed of 24 Mbps. The latest version is 4.0.

Connections

Generally, the devices which are connected through Bluetooth are very secure from hacking. As they work with different frequencies & the devices which jump between these frequencies were 100s of times for every second which is called the “frequency-hopping spread spectrum”.

This device is frequently used for connecting mobile devices otherwise fixed devices. But it is also working to link a printer otherwise mouse toward a computer. As Bluetooth &?Wi-Fi?are frequently complementary, so they work at the same time & provides the same connectivity, so you cannot find out which hardware is connected. Most tablets, computers, smartphones simply permit connecting with one device that is Bluetooth enabled at a time.

How Bluetooth Works?

Bluetooth Network consists of a Personal Area Network or a piconet which contains a minimum of 2 to a maximum of 8 BlueTooth peer devices- Usually a single master and upto 7 slaves. A master is a device that initiates communication with other devices. The master device governs the communications link and traf?c between itself and the slave devices associated with it. A slave device is a device that responds to the master device. Slave devices are required to synchronize they’re transmit/receive timing with that of the masters.

In addition, transmissions by slave devices are governed by the master device (i.e., the master device dictates when a slave device may transmit). Speci?cally, a slave may only begin its transmissions in a time slot immediately following the time slot in which it was addressed by the master, or in a time slot explicitly reserved for use by the slave device.

The frequency hopping sequence is defined by the Bluetooth device address (BD_ADDR) of the master device.?The master device first sends a radio signal asking for a response from the particular slave devices within the range of addresses. The slaves respond and synchronize their hop frequency as well as a clock with that of the master device.

Scatternets are created when a device becomes an active member of more than one piconet. Essentially, the adjoining device shares its time slots among the different piconets.

Bluetooth Architecture

The Bluetooth architecture uses two networks like Piconet and ScatternetPiconet Network

Piconet is one kind of wireless network that includes one main node namely the master node as well as seven energetic secondary nodes are known as slave nodes. So, we can declare that there are eight active nodes totally which are arranged at a10 meters distance. The message between these two nodes can be done one-to-one otherwise one-to-many.

Communication can be possible only among the master and slave but the communication like Slave-slave cannot be possible. It also includes 255 parked nodes which are known as secondary nodes. These cannot communicate until it gets altered to the active condition.

Scatternet Network

The formation of the Scatternet Network can be done through various piconets. On one piconet, a slave is present which acts as a master otherwise it can be called primary within other piconets. So, this type of node gets a message from the master within one piconet & transmits the message toward its slave in another piconet wherever it works like a slave. So, this kind of node is called a bridge-node. In two piconets, a station cannot be master.

Types of Bluetooth

This technology eliminates the necessity of wires and cables. At present, this technology has seen a fast growth of Bluetooth-enabled devices.

Headsets

The most commonly known device is the Bluetooth headset. Generally, a headset allows a person to make as well as receive calls through a mobile phone without using your hands otherwise wires. These headsets are prepared with voice recognition, thus one can dial & talk without utilizing a mobile handset.

Stereo Headset

The function of a?stereo headset is similar to a normal headset without using wires. The connection of a stereo headset can be done to any Bluetooth-enabled device like the music player. So, it permits the user to hear the music in a short range of your music player device. This headset also supports mobile phones.

Bluetooth System In-Car

An in-car Bluetooth system connects the mobile phone to the sound system in your vehicle. So, you can make & receive phone calls through the speaker system without using a mobile device.

Printer

A printer with Bluetooth enabled can get files like pictures and text documents from any device that is equipped with a blue tooth like a PDA or laptop & print the data without using wires. This device must be connected to the printer for the purpose of printing to work properly.

Webcam

A webcam enabled by Bluetooth mainly works as a usual webcam without the requirement of wires. The wireless capabilities add mobility to the device, unlike traditional webcams, which remain docked onto or near the computer.

GPS Device

A Bluetooth-enabled?GPS device?is an essential device as compared to normal GPS because it permits you to converse through the device with voice. Once the device is communicated through voice then the device will find the address and also provide the directions over the display using voice command.

Keyboard

A Bluetooth-enabled keyboard mainly works like a normal keyboard, without using wires to connect the device to a PC. This keyboard also functions through particular smartphone devices.

Specifications

The?Bluetooth specifications?include the following.

• Core Specifications: It de?nes the Bluetooth protocol stack and the requirements for testing and quali?cation of Bluetooth-based products.
• The Pro?les Speci?cation:?It de?nes usage models that provide detailed information about how to use the Bluetooth protocol for various types of applications.

?The core specifications of Bluetooth consists of 5 layers

• Radio: Radio speci?es the requirements for radio transmission – including frequency, modulation, and power characteristics – for a Bluetooth transceiver.
• Baseband Layer: It de?nes physical and logical channels and link types (voice or data); speci?es various packet formats, transmit and receive timing, channel control, and the mechanism for frequency hopping (hop selection) and device addressing.It specifies point to point or point to multipoint links. The length of a packet can range from 68 bits (shortened access code) to a maximum of 3071 bits.
• LMP- Link Manager Protocol (LMP):?It de?nes the procedures for link setup and ongoing link management.
• Logical Link Control and Adaptation Protocol (L2CAP):?It is responsible for adapting upper-layer protocols to the baseband layer.
• Service Discovery Protocol (SDP):?– Allows a Bluetooth device to query other Bluetooth devices for device information, services provided, and the characteristics of those services.