What is Bluetooth Technology ???
Bluetooth a (wireless short range communication) technology uses low-power microwave radio signals than cables to connect the electronic devices. The technology uses low-power radio links to connect the computer with its connecting devices over short distances without wires. This technology is use to transfer the data at the rate of 720 kbps within the range of 10 to 100 meters. By using this technology, you share voice, music,photos, and other type of the data wireless with much security between two paired devices.
The technology was basically invented to replace the wires with wireless use but now this is used to create new connections that are not possible with the wired system as now you can create a connection between your mobile phone and car stereo and also can print a picture with your mobile device. When two devices are connect with Bluetooth then it is called pairing between them. The Bluetooth technology is able to handle data and voice transmission simultaneously and provide user many solutions as hands-free handset for voice calls, printing and fax capability, and synchronization for PC and mobile phones. This technology provides both link-layer and application layer to support data and voice applications.
The technology uses spread spectrum, frequency hopping, full-duplex signals at 1600 hops/sec and operates at 2.4 to 2.485 GHz in ISM band. Frequency hopping capability is used to reduce the interference between the spectrum sharing. This is done to take the advantage the available frequency. This hopping capability give a high degree of immunity interference and allowed more efficient transmission within the spectrum.
How does Bluetooth work ???
Bluetooth was developed to create a wireless protocol that is capable of connecting multiple devices and resolve synchronization problem. The Bluetooth technology uses a RFtopology called ‘star topology’. The devices grouped in this manner form a piconet. This piconetcontains one master and seven other active slaves. It has other slaves but they are not active in the network. In this piconet, the physical radio channel is shared by synchronize group of devices with master device providing synchronization.
Bluetooth is based on data packet technology with piconetarchitecture. The main device that transfer data is known as master device and other devices are known as active slaves. The hopping pattern is decided by the master device and basically is pseudo random pattern with 79 frequencies. The wireless link is dividedinto time slots and data is transmitted between Bluetooth enabled devices in packets according to these time slots. Frequency hopping takes place between transmission and reception of packets. This channel also supports synchronous and asynchronous traffic as well as broadcast traffic. Synchronous traffic is used to carry hands-free audio data and asynchronous traffic is used to carry other data with time variability capability.
When data is send from one device to another, before it, data is divided into chunks with equivalent size. The clock synchronize ticks for data transfer and timing is set according to data. First pairing is done between two connecting devices and two ticks are used to make a pair and others are used to transfer the complete file. A piconetis the collection of devices connected through Bluetooth. Multiple independent and non-synchronized piconetcan form a scatterer. Any device of piconetcan be member of other piconetby time multiplexing. The technology allows the p-to-p or p-to-multiple-p connections. If one device is connected in more than on epiconet, then it communicates in each piconetusing different hopping pattern.
Establishing network connections :
In order to establish the connection, two procedures inquiry and paging are used. The enquiring is used to discover the existing device within the range with turn-up Bluetooth, and paging procedure is used to make the connection between them. To establish the connection, we require the Bluetooth device’s address. The unit that establish the connection will carry out the paging procedure. After paging procedure the master device send the POLL or NULL packets for slave access. When the paging device wants to make a connection above LM, it sends LMPhost request , when other side receives this request, the host is informed about the connection. The remote device can then accept or reject the request by sending LMPaccept or reject message. When other connection are not require, then LMPcomplete message is send. Then device start the connection from other device until its finish message.
Features of the Bluetooth technology :
1. Ultra-low peak, average, and idle mode power consumption
2. Ability to run for years on standard, cell batteries
3. Low cost
4. Enhanced range
5. Global usages
6. Voice and data handling
7. The ability to establish ad-hoc connections
8. Very small in size
9. Secure transfer of data between many devices
10. Available in almost all type of mobile hand-set.
11. Less time consuming
12. Flexible and reliable data transfer
13. Ensure confirmation form both connecting device
14. 1 Mb/sec. Transmission/reception rates
15. short packet maximizing capacity
16. low power minimizing interference
17. fast frequency hopping minimizing interference
Problems with Bluetooth technology :
1. A tangle of cables
2. Varying standard of cables and connectors
3. unreliable galvanic connections
4. re-configuration of units
5. manual switches when ports are not sufficient
6. Need of confirmation on both side
7. plugging of both device
Advantages of technology :
1. Simple setup
3. Less hardware
5. Standard protocol
8. Upgrade able
10. Simplify the communication during driving
11. Instant PAN
12. Don’t need to be face to face
Applications of The technology :
1. Wireless networking between laptop and desktop
2. Transfer of the data
3. Use in E-commerce ‘and retail in future
4. Home networking
5. cable -less connection to printer, fax, cameras
6. Dial-up and automatic e-mail
7. Use of PDA or PC as hands free phone
8. Automatic exchange of files
9. Bluetooth interface to office PBX
10. Use of cell phone as office cordless phone