Anis Liyana Abd Rahman
14415
Bluetooth is one of method for data communication that uses short- range radio links to replace cable between computers and their connected units. Bluetooth is an open standard for wireless connectivity that supports mostly from the PC and cell phone industries. It is a primary market for data and voice transfer between communication devices and PCs.
Bluetooth is a radio frequency (RF) technology that utilizing the unlicensed 2.5 GHz industrial,
scientific, and medical (ISM) band. The target applications for Bluetooth include PC and peripheral networking, hidden computing and data synchronization such as for address books and calendars.
Other applications could include smart home networking and home appliances of the future such as smart appliances, heating systems and entertainment devices.
Bluetooth History
Bluetooth was created in 1994 by L. M. Ericsson (telecoms vendor) of Sweden. Bluetooth was named after Harald Blaatand “Bluetooth” II, king of Denmark 940–981A.D. The story goes when a runic stone has been erected in a capitol city Jelling (Jutland) in which he ruled, that depicts the knighthood of Harald said:
- Harald christianized the Danes.
- Harald controlled Denmark and Norway.
- Harald thinks notebooks and cellular phones should continuously communicate.
Bluetooth is managed by Bluetooth Special Interest Group (SIG) which was founded by Ericsson,
IBM, Intel, Nokia, and Toshiba in February 1998 in order to develop an open specification for shortrange wireless connectivity. The group is now also promoted by 3COM, Microsoft, Lucent, and Motorola. There are approximately more than 1900 companies have joined the SIG.
Why Using Bluetooth
Significantly, Bluetooth attempts to provide advantages over other data transfer technologies, such as IrDA and HomeRF competing for similar markets. Despite comments from the Bluetooth SIG indicating that the technology is complementary to IrDA, it is definitely a fierce competition for PCto- peripheral connection. IrDA is more popular in PC peripherals, but due to the limitation by the short connection distance of 1m and the line of sight requirement for communication. This limitation eliminates the feasibility of using IrDA for hidden computing, where the communicating devices are nearby but not visible to one another. On the other hand, Bluetooth is not subject to such limitation due to its RF nature.
Besides, Bluetooth has the capability for wireless device connections up to 10 m (could be up to 100 m if the transmitter’s power is increased), in addition with the devices need not be within line of sight and may even connected through walls or other non-metal objects. This allows for applications such as a cell phone in a pocket or a briefcase acting as a modem for a laptop or PDA. As a matter of fact, Bluetooth is designed to be low cost. Thus it has the greatest advantages however, there are few flips side of this advantage such that the limited connection distance and also the transmission speeds. Bluetooth supports only 780 kbps. These rates are comparable to the 1–2 Mbps supported by HomeRF and although live digital video is still beyond the capability of any RF technology, perfectly adequate for file transfer and printing applications.
The main strength of Bluetooth is its ability to simultaneously handle both data and voice transmissions. It is capable to support one asynchronous data channel and up to three synchronous voice channels or one channel supporting both voice and data. This capability will make the greatest solution for mobile devices and Internet applications as it combines with ad hoc device connection and automatic service discovery. Such combination will produce innovative solutions for example, mobile hands-free headset for voice calls, print to fax capability and automatically synchronizing PDA and cell phone address book applications.
Architecture Overview
Bluetooth link the control hardware as either one chip or a radio module and a baseband module implementing the RF. This hardware handles radio transmission and reception as well as required digital signal processing for the baseband protocol. Its can establish connections, support for asynchronous (data) and synchronous (voice) links, error correction and authentication. The link manager firmware provided with the baseband CPU performs low-level device discovery, link setup, authentication and link configuration. Link managers on separate devices communicate using the Link Management Protocol, which utilizes the services of the underlying link controller (baseband).
Network Topology
Basically, Bluetooth devices are organized into groups of two or to eight devices called piconets, consist of a single master device and one or more slave devices. A device can belong to more than one piconet and it will connect the piconet into a scatternet. Bluetooth operates in the unlicensed ISM frequency band, in order to help Bluetooth devices coexist and operate reliably alongside other ISM devices, each Bluetooth piconet is synchronized to a specific frequency hopping pattern. This pattern, moving through 1600 different frequencies per second and each frequency hop is a time slot during which data packets are transferred.
Baseband State Machine
Piconets may be static or dynamically as devices move in and out of range of one another. A device leaves standby (the low-power default state) by initiating an inquiry page of command. An inquiry may be used if the address of a targeted device is unknown and must be followed by a page command. A page command containing a specific DeviceAccess-Code is used to connect to a remote device. When the remote device responds, both devices enter the connected state, with the initiating device becoming the master and the responding device acting as a slave. Once in the connected state, the slave device will synchronize to the master’s clock and to the correct frequency-hopping pattern.
Today, most of the devices have implementing Bluetooth thus in the near future, Bluetooth is likely to be standard of more than tens of millions of electronic devices. As a result, the market is going to demand new innovative applications, valueadded services and much more. The possibilities opened up really are limitless and since the radio frequency used. In addition, SIG continues to improves and analyzing for the betterment of Bluetooth in the communication industry.
Reference
K. Sairam, N. Gunasekaran, & S. Reddy, “Bluetooth in Wireless Communication”, IEEE
Communications Magazine, June, 2002, pp. 90-96.
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