Blue tooth is initially conceived by Ericsson. The five founding members of the Bluetooth SIG are Ericsson, IBM, Intel, Nokia and Toshiba. On December 1, 1999, the founding members announced that 3COM, Lucent, Microsoft, and Motorola have joined the founders to form the Promoter Group with the founding companies. To date, more than 1,200 companies have signed on. Bluetooth is a standard for a small, cheap radio chip to be plugged into computers, printers, mobile phones, etc. www.descol.hr
Blue thooth is a cable- replacement technology. It uses radio frequencies in the 2.45 GHz range to transmit information over short distances of generally 33 feet (10 meters) or less. By embedding a Bluetooth chip and receiver into products, cables that would normally carry the signal can be eliminated.
A Bluetooth chip is designed to replace cables by taking the information normally carried by the cable, and transmitting it at a special frequency to a receiver Bluetooth chip, which will then give the information received to the computer, phone whatever.
o Piconet: Devices connected in an ad hoc fashion that is, not requiring predefinition and planning, as with a standard network. Two to eight devices can be networked into a piconet. It is a peer network that is, once connected each device has equal access to the others. However, one device is defined as master, and the others as slaves.
o Scatternet: Several piconets may form a larger scatternet, with each piconet maintaining independence.
o Master unit: The master in a piconet whose clock and hopping sequence synchronizes the other devices.
o Slave unit: Devices in a piconet that are not the master.
o MAC address: Three bit address that distinguishes each unit in a piconet.
o Parked units: Piconet devices that are synchronized but don’t have MAC addresses.
o Sniff and hold mode: Power-saving mode of a piconet device.
Overview of Bluetooth characteristics
These are the features of the Bluetooth technology:
1. It separates the frequency band into hops. This spread spectrum is used to hop from one channel to another, which adds a strong layer of security.
2. Up to eight devices can be networked in a piconet.
3. Signals can be transmitted through walls and briefcases, thus eliminating the need for line-of-sight.
4. Devices do not need to be pointed at each other, as signals are omni-directional.
5. Both synchronous and asynchronous applications are supported, making it easy to implement on a variety of devices and for a variety of services, such as voice and Internet.
6. Governments worldwide regulate it, so it is possible to utilize the same standard wherever one travels.
How could Bluetooth be used?
Well, it’s very much up to our imagination. But the ambition is set high, indeed; practically all computerized equipment normally found in a modern office (and home) which do not use a synchronous communications protocol could be adapted for use with Bluetooth.
Check this list:
Phones and pagers, Modems, LAN access devices, Headsets, Notebook computers,
Desktop and handheld computers, Printers, Fax machines, Keyboards, Joysticks etc
Virtually any digital device can be part of the Bluetooth system. Bluetooth radio technology can also provide a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small ad hoc groupings of connected devices, away from fixed network infrastructures. The dynamic connectivity-nature of Bluetooth makes it possible for this system to replace USB, and it is an improvement on Plug-and-Play-systems, where the operating system has to be rebooted for the installation to take effect.
Basic Bluetooth functions
The Bluetooth technology is quite complex. This is not so surprising, considering the task it has to handle. It is mainly based on the IEEE 802.11 standard, briefly described at right. Of the 2 network modes described, Bluetooth uses the ad-hoc mode. This means that each station must observe “netiqette” and give all other units fair access to the wireless media.
The IEEE 802.11 communications standard defines the protocol for two types of networks; Ad-hoc and client/server.
The Ad-hoc network is a simple network where communications are established between multiple stations in a given coverage area without the use of an access point or server.
The client/server network uses an access point that controls the allocation of transmit time for all stations and allows mobile stations to roam from cell to cell. The access point is used to handle traffic from the mobile radio to the wired or wireless backbone of the client/server network. This arrangement allows for point coordination of all the stations in the basic service area and ensures proper handling of the data traffic. The access point routes data between the stations and other wireless stations or to and from the network server.
How does Blue Tooth works?
Bluetooth uses frequency hopping in timeslots. Bluetooth has been designed to operate in noisy radio frequency environments, and uses a fast acknowledgement and a frequency-hopping scheme to make the communications link robust, communication-wise. Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet.
Compared with other systems operating in the same frequency band, the Bluetooth radio typically hops faster and uses shorter packets. This is because short packages and fast hopping limit the impact of microwave ovens and other sources of disturbances. Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links.
Establishing network connections
In order to establish new connections the procedures inquiry and paging are used. The inquiry procedure enables a unit to discover which units are in range, and what their device addresses and clocks are. With the paging proce-dure, an actual connection can be established. Only the Bluetooth device address is required to set up a connection. Knowledge about the clock will accelerate the setup procedure. A unit that establishes a connection will carry out a page procedure and will automatically become the master of the connection.
For the paging process, several paging schemes can be applied. There is one mandatory paging scheme which has to be supported by each Bluetooth device. This mandatory scheme is used when units meet for the first time, and in case the paging process directly follows the inquiry process. Two units, once connected using a mandatory paging/scanning scheme, may agree on an optional paging/scanning scheme.
What kind of traffic can Bluetooth handle?
Bluetooth is specifically designed to provide low-cost, robust, efficient, high capacity, ad hoc voice and data networking with the following characteristics:
1. 1 Mb/sec. transmission/reception rate exploits maximum available channel bandwidth.
2. Fast frequency hopping avoids interference.
3. Adaptive output power minimizes interference.
4. Short data packets maximize capacity during interference.
5. Fast acknowledge allows low coding overhead for links.
6. CVSD (Continuous Variable Slope Delta Modulation) voice coding enables operation at high bit-error rates.
7. Flexible packet types supports a wide application range.
8. Relaxed link budget supports low-cost single chip integration.
9. Transmission/reception interface tailored to minimize electric current consumption
What about Bluetooth’s security?
Security can mean two things in this context:
o A) We want to be sure that transmitted data arrives in un-corrupted condition to the receiver.
o B) We also want to feel that this data has not been eaves dropped by parties for whom it is not intended.
Both of these issues are (of course!) addressed by Bluetooth.