What is Bluetooth?

Bluetooth wireless technology is a de facto standard, as well as a specification for small form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices. The Bluetooth Special Interest Group is an industry group consisting of leaders in the telecommunications, computing, and networking industries that are driving development of the technology and bringing it to market.

How did the need arise?

In phase with the IT boom, the mobility among people has constantly grown and wireless technologies for voice and data have evolved rapidly during the past years. Countless electronic devices for home, personal and business use have been presented to the market during recent years but no widespread technology to address the needs of connecting personal devices in Personal Area Networks (PANs). The demand for a system that could easily connect devices for transfer of data and voice over short distances without cables grew stronger.

Bluetooth wireless technology fills this important communication need, with its ability to communicate both voice and data wirelessly, using a standard low-power, low-cost technology which can be integrated in all devices to enable total mobility. The price will be low and result in mass production. The more units around, the more benefits for the customer.

Why Bluetooth ?

What will Bluetooth wireless technology deliver to end users?

It will enable users to connect a wide range of computing and telecommunications devices easily and simply, without the need to buy, carry, or connect cables. It delivers opportunities for rapid ad hoc connections, and the possibility of automatic, unconscious, connections between devices. It will virtually eliminate the need to purchase additional or proprietary cabling to connect individual devices. Because Bluetooth wireless technology can be used for a variety of purposes, it will also potentially replace multiple cable connections via a single radio link. It creates the possibility of using mobile data in a different way, for different applications such as "Surfing on the sofa", "The instant postcard", "Three in one phone" and many others. It will allow them to think about what they are working on, rather than how to make their technology work. The solution eliminates the annoying cable and its limitations regarding flexibility (often specific for a brand or pair of devices) and range. But, Bluetooth implies more than that. The technique provides the means for connecting several units to each other such as setting up small radio LANs between any types of Bluetooth devices. A number of user scenarios are described. They highlight more possibilities that reach far beyond just an elimination of the point-to-point cable.

History

         

By the way if, you're wondering where the Bluetooth name originally came from , it is named after a Danish Viking and King of Denmark between 940 and 981 AD, Harald Blåtand (Bluetooth in English), who lived in the latter part of the 10^TH  century. Harald Blåtand united and controlled Denmark and Norway (hence the inspiration on the name : uniting devices through Bluetooth

          The idea that resulted in the Bluetooth wireless technology was born in 1994 when Ericsson Mobile Communications decided to investigate the feasibility of a low-power, low-cost radio interface between mobile phones and their accessories. The idea was that a small radio built into both the cellular telephone and the laptop would replace the cumbersome cable used today to connect the two devices.

A year later the engineering work began and the true potential of the technology began to crystallize. But beyond unleashing devices by replacing cables, the radio technology showed possibilities to become a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures.

The requirements regarding price, capacity and size were set so that the new technique would have the potential to outdo all cable solutions between mobile devices. Initially a suitable radio interface with a corresponding frequency range had to be specified. A number of criteria for the concept were defined regarding size, capacity and global uniformity. The radio unit should be so small and consume such low power that it could be fitted into portable devices with their limitations. The concept had to handle both speech and data and finally the technique had to work all around the world. The study soon showed that a short-range radio link solution was feasible.

When designers at Ericsson had started to work on a transceiver chip, Ericsson soon realized that they needed companions to develop the technique. The associates strove not only to improve the technical solutions but also to get a solid and broad market support in the business areas of PC hardware, portable computers and mobile phones. Fear for a market situation with a multitude of non-standard cable solutions, where one cable is designed specifically for one pair of devices, was one of the motives that made competing companies join the project. Ericsson Mobile Communications, Intel, IBM, Toshiba and Nokia Mobile Phones formed a Special Interest Group (SIG) in 1998.

What is  SIG?

          In February 1998 the Special Interest Group (SIG) was formed. Today the Bluetooth SIG includes promoter companies 3Com, Ericsson, IBM, Intel, Lucent, Microsoft, Motorola, Nokia and Toshiba, and thousands of Adopter/Associate member companies. By signing a zero cost agreement, companies can join the SIG and qualify for a royalty-free license to build products based on the Bluetooth technology.

This group represented the diverse market support that was needed to generate good support for the new Bluetooth technology. In May of the same year, the Bluetooth consortium announced itself globally. The assignment of the SIG originally was to monitor the technical development of short-range radio and to create an open global standard, thus preventing the technology from becoming the property of a single company. This work resulted in the release of the first Bluetooth Specification in July 1999.

The intention of the Bluetooth SIG is to form a de facto standard for the air interface and the software that controls it.  The further development of the Specification still is one of the main tasks for the SIG, other important ones being interoperability requirements, frequency band harmonization and promotion of the technology. The Bluetooth wireless technology was developed by the Bluetooth Special Interest Group, to define an industry-wide specification for connecting personal and business mobile devices. More than 1,4000 companies are now members of the Special Interest Group, signifying the industry’s unprecedented acceptance of the Bluetooth wireless technology.

To avoid different interpretations of the Bluetooth standard regarding how a specific type of application should be mapped to Bluetooth, the SIG has defined

number of user models and protocol profiles. These are described in more detail in the section entitled Bluetooth Usage Models and Profiles.The SIG also works with a Qualification Process. This process defines criteria for bluetooth product qualification that ensures that products that pass this process meet the Bluetooth specification

TECHNOLOGY OVERVIEW:

The technology is an open specification  for wireless communication of data and voice. It is low cost short range radio link, built into a 9X9 mm microchip, facilitating protected ad hoc connections for stationary and mobile communication environment. Bluetooth technology allows for the replacement of the many proprietary cables that connect one device to another device with one universal short range radio link. For instance Bluetooth radio technology built in both the cellular telephone and the laptop would replace the cumbersome cables used today to connect the laptop to a cellular telephone.

Printers, PDA’S, desktops, fax machines, keyboard, joysticks and virtually any other device can be part of the Bluetooth system. But beyond untethering devices by replacing the cables, Bluetooth radio technology provides a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc grouping of connected devices away from fixed network infrastructures. Designed to operate in noisy radio frequency environment, the Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust. The 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 makes the Bluetooth radio robust than the other system. Short packages and fast hopping also limit the impact of random noise and long distance links. The encoding is optimized for uncoordinated environment. Bluetooth radios operate in the unlicensed ISM band at 2.4GHz. a frequency hop transceiver is applied to combat interference and fading. A shaped binary FM modulation is applied to minimize transceiver complexity. The gross data rate is 1mbps. A Time Division Duplex scheme is used for full duplex transmission. The Bluetooth base band protocol is a combination of circuit and packet switching. Slots can be reserved for synchronous packet. Each packet is transmitted in a different hop frequency. A packet nominally covers a single slot, but can be extended to cover up to 5 slots. Bluetooth can support an asynchronous data channel, up to 3 simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous data synchronous voice. Each voice  channel supports 64 kbps synchronous (voice) link.

The asynchronous channel can support an asymmetric link of maximally 721 kbps in either direction  while permitting 57.6 kbps in the return direction, or a 432.6 kbps symmetric link.

INTRODUCTION :

The Bluetooth technology answers the need for short range wireless connectivity within three areas :

·     Data and voice access points .

·        Cable replacement

·        Ad hoc networking

The Bluetooth technology specification specifies a system solution comprising hardware, software and interoperability requirements. The Bluetooth radio operates in a globally available 2.4GHz  ISM  band, ensuring communication compatibility worldwide.       

Data and voice access point :

The Bluetooth technology facilitates real time voice and data transmission. The technology makes it possible to connect any portable and stationary communication device as easily as switching on the light. You can, for instance, surf the Internet & send e-mail on your potable PC or notebook regardless of whether you are wirelessly connected through a mobile phone or through a wire bound connection (PSTN, ISDN,LSN,XDLS).

          Voice channel use the Continuous Variable Slope Delta Modulation (CVSD) coding scheme, and never retransmit voice packets. The CVSD was chosen for its robustness in handling dropped and damaged samples. Rising interference levels are experienced as increased background noise; even at bit error rate up to 4% the CVSD coded voice is quite audible.

CABLE REPLACEMENT:

The Bluetooth technology eliminates the use for numerous often proprietary cable attachments for connection of practically any kind of device. Connections are instant and they are maintained even when devices are not within line of sight. The range of each radio is approximately 10 meters but it can be extended around 100 meters with an optional amplifier.

AD-HOC NETWORKING:

A device equipped with Bluetooth radio establishes instant connection to another Bluetooth radio as soon as it comes into range. Since Bluetooth technology supports both point to point and point to multi point connection, several piconets can be established and linked together ad hoc. The Bluetooth technology is best described as multiple piconet structure.

Piconet is a connection of devices connected via Bluetooth technology in an ad hoc fashion . A piconet starts with two connected devices ,such as portable PC and cellular phone and may grow into eight connected devices. All Bluetooth  devices are peer units and have identical  implementation. However, when establishing a piconet, one unit will act as a master and the other as a slave for the duration of piconet connection.