BLUETOOTH Amita Tiwari IIIrd Semester amitaasct@gmail.com Sunil Kumar IIIrd Semester sunilasct@gmail.com ALL SAINTS COLLEGE OF TECHNOLOGY, BHOPAL ABSTRACT Blue tooth is a standard developed by a group of electronics manufacturers that allows any sort of electronic equipment from computers to cell phones and keyboards to headphones to make its own connections without wires, cables or any direct action from the user. The technology encompasses a simple low-cost, low-power, global radio system for integration into mobile devices. Such devices can form a quick ad-hoc secure Piconet and communicate among the connected devices. This technology creates many useful mobile usage models because the connections can occur while mobile devices are being carried in packets and briefcases (therefore, there are no line-ofsight restrictions). This paper provides a brief introduction of Bluetooth technology and its working. It also gives some of applications, features and benefits. Finally, the implementation issues of Bluetooth technology are observed. Bluetooth has to receive an overwhelming support of all the digital and computerized manufacturers to become a basic unit in a production process. Acceptance by those companies outside the SIG will hold back the implementation of Bluetooth in all devices in the future. Bluetooth is a radio system designed for connecting a variety of mobile devices in a secure ad-hoc fashion. The Bluetooth specification is definitely real and is being widely adopted by industry leaders. The possibilities for new applications are very exciting with this versatile technology. INTRODUCTION Today wireless communication is one of the fastest growing technologies. One of the promising technologies for WLAN s (Wireless Local Area Network) is BLUETOOTH. LAN (Local Area Network) is a computer network designed for connecting devices in a limited geographic area such as a building or a campus where as WLAN is a LAN, which uses unguided media (Without using cables or any connections). It is used for connecting roaming devices & provides a high-speed backbone network to enable security. Bluetooth technology was born in 1994.First version was released in July 1999. WHAT IS BLUETOOTH? Bluetooth is a name given to the novel technology that uses short range, radio link, intended to replace the cables connecting portable and/or fixed communicating devices. Such as mobile phones, desktops, notebook computers, cameras, printers, coffee makers, telephones etc. OR Bluetooth wireless technology is an open
specification for a low cost, low power, short range, radio technologies for ad-hoc wireless communication of voice and data any where in the world. THE NAME BLUETOOTH COMES FROM Bluetooth is named for Harald Blatand, the king of Denmark who united Denmark and Norway. Blatand translates into Bluetooth in English. The Ericsson Company originally started Bluetooth as a project. Similarly, in the beginning of the Bluetooth technology era, Bluetooth was aimed at unifying the telecom and computing industries. THE REASON WE CAME TO BLUETOOTH Let us take an example of telephones for cables where as mobiles are wireless. Because of the problem of interference over cabling we came to Bluetooth technology. This Bluetooth is also a cable replacement technology i.e. wireless. BLUETOOTH IS WIRELESS Blue tooth uses Omni-directional radio waves which even operate in the unlicensed ISM band at 2.4GHZ that can be transmitted through walls and non-metal barriers. Bluetooth uses 1600 times/sec frequency hopping to avoid interference. BLUETOOTH CONTROLLER The Bluetooth Special Interest Group (SIG) This group worked together to define and promote an open, royalty-free specification. This group also defines a certification program for Bluetooth products to ensure product compatibility across manufacturers. The Bluetooth SIG includes promoter companies 3Com, Ericsson, IBM, Intel, Lucent, Microsoft, Motorola, Nokia and Toshiba, and more than 2000 Adopter/Associate member companies. FEATURES Universal short-range (up to 100 mts) radio communication standard. Runs at 2.4GHz band, which is near microwave frequency. Performs fast frequency hopping between 79 points to avoid interference i.e., 1600 times/sec. It is full-duplex. Low power, 32-100mA during sustained data transmissions between devices. Devices automatically switch to power saving mode. Transfers data at 721 Kbps (Kilo Bits Per Second), which is 3 8 times the average speed of parallel and serial ports respectively. Bandwidth is wide enough to carry voice and data signals. 300 400 Kbps real data rate. NETWORKS Bluetooth defines two types of networks. Pico net Scatter net PICONET It is a small subset of Bluetooth devices that share the same physical channel in an ad-hoc fashion. Pico net comprises of eight stations in which only one serves as master & the rest as slaves. All the slave stations synchronize their clocks & hopping sequence with the master. An indefinite number of parked devices remains synchronized with the Pico net but is not active. A slave in the parked state is synchronized with the master but cannot take place in communication until it moves from parked state to active state. Activating a station from parked state means that an active station should be moved to
parked state. The communication between master & slaves can be of One-to-one (or) single point-to-point One-to-many (or) multipoint This layer uses 2.4GHz ISM band divided into 79 channels of 1MHz each.in this layer a method called Frequency hopping spread spectrum is used in order to avoid interference from other devices or other networks. To transform bits to a signal a sophisticated version of FSK called GFSK (FSK with Gaussian Band Width Filtering) is used. BASE BAND LAYER: SCATTERNET A group of two or more partially overlapping Pico net connected through gateways. (Or) A Scatter net is a group of Piconet linked via a slave device in one Pico net, which plays master role in other Pico net. The connection between master and slaves is same as in Pico net. In Scatter net the slave of one Pico net can be a master to another Pico net. BLUETOOTH LAYERS Base band layer governs the operation of the access method. It deals with access method TDMA & Physical links. This layer deals with access method TDD-TDMA (Time Division Depleting Time Division Multiple Access). TDD is a kind of half duplex communication. The communication for each direction uses different hops. TDMA: In TDMA access method communication is of two types: SINGLE SLAVE COMMUNICATION If the Pico net has only one slave then the master uses even numbered slots and the slave uses odd numbered slots to communicate with one another in half duplex method. MULTIPLE SLAVE COMMUNICATION If the Piconet consists more than one slave then the master uses the even numbered slots, but a slave sends in the next odd numbered slot if the packet in the previous slot was addressed to it. RADIO LAYER The radio layer coordinates the functions required to transmit bit stream over a medium. It deals with Band, FHSS & Modulation. PHYSICAL LINKS: The types of links between master and slave are SCO (Synchronous Connection Oriented) link ACL (Asynchronous Connection Less) link SCO: A synchronous connection oriented link is
used when avoiding Latency (delay in data delivery) is more important than integrity (Error-free delivery). In SCO, a physical link is created between a master and slave by reserving specific slots at regular intervals. In SCO, if a packet is damaged it is never retransmitted. So, SCO is used for real- time audio. A slave can create up to three SCO links with the master ACL: An Asynchronous connectionless link is used when data integrity is more important than avoiding latency. ACL can achieve a data rate up to 721 Kbps. LMP (Link Manager Protocol) This layer is responsible for setting up the link between two Bluetooth radios (Security aspects and control issues on Baseband packet sizes). Link manager uses the services of link controller to perform its services. It essentially consists of number of protocol data units, which sends from one device to another. Furthermore, it controls the power modes and duty cycles of Bluetooth radio services, and connection states of Bluetooth unit in a Pico net. HCI (Host Controller Interface) It is provided to ease the partition of the Bluetooth Stack across to processors. Some systems will implement the Baseband and link manager on the Bluetooth device and higher levels on the host processor. The HCI is provided as command interface between these parts. This HCI is functionally broken up into three parts. HCI Firmware, HCI Driver & Host Controller Transport Layer HCI Firmware & HCI Controllers are communicated through Host Controller Transport Layer. L2CAP LAYER: L2CAP is the acronym for Logical Link Control & Adaptation Protocol. L2CAP adapts upper layer protocols over the Baseband and resides in the data link layer. L2CAP permits higher-level protocols and applications to transmit and receive L2CAP data packets up to 64KB of length. PROFILES It provides interoperability between devices from different manufacturers for specific services and use cases. A profile defines a selection of messages and procedures and gives an unambiguous description of communication between two devices. BLUETOOTH DEVICES Bluetooth devices are required where cable replacement needed and at data and voice access points, ad-hoc networking and some like in medical or industrial organizations. Cable Replacement PCs &peripherals, home networking, headsets Data and Voice Access Points E-mail, web access, Cordless telephone, etc. Ad-hoc Networking Business card exchange, multi-layer Games, vending machines, white goods, etc. Medical Monitoring devices Industrial Inventory management systems ADVANTAGES 1. Allows transmission range of up to 100 meters 2. Robustness: This is capable of operating in an environment strongly interfered by other technologies using the same radio spectrum
3. Low Complexity: This is suitable for devices with low memory and low cpu capacity, so that it could be easily integrated in chipsets 4. Low Power: This is suitable for small devices that are battery powered and energy constrained 5. Low Cost: Very large scale production can be implemented on a single chip 6. Bluetooth devices are wireless DISADVANTAGES 1. Only applicable to short range (up to 100 mts) 2. Bluetooth technology is of high cost when compared to other technologies. 3. Relatively low transfer rate (721Kbps) COMPETITOR the other WLAN technology is IEEE 802.11b Office or campus LAN 11 Mbps Multiple clients per access point Up to 100 meters range Uses Wired Equivalent Privacy APPLICATIONS Headset Hands free cell phone (road, office, and car) 3 in 1 Phone Intercom (no charge), Portable phone (fixed line charge), Cellular in Office LAN Internet Bridge Network access point, for mobile internet browsing Automatic Synchronizer Syncs between PC & PDA, Phone, PC Instant Postcard Digital camera send to cell phone Interactive Conference Exchange Business Cards & Data in meetings Wireless Workplace Peripherals connect to your PC or LAN w/o wires CONCLUSION Bluetooth is a radio system designed for connecting a variety of mobile devices in a secure ad-hoc fashion. The Bluetooth specification is definitely real and is being widely adopted by industry leaders. The possibilities for new applications are very exciting with this versatile technology. REFERENCES 1.Computer Network-Tanenbaum 2. Bluetooth Specifications, Bluetooth SIG at http://www.bluetooth.com 3. Bluetooth Technical Overviews, Bluetooth SIG at http://www.bluetooth.org 4. Bluetooth Technology, http://www.gsmdata.com/artblue.com