What is Bluetooth?

Bluetooth is a low cost, low power, short-range radio technology, originally developed as a cable replacement to connect devices such as mobile phone, handsets and portable computers.

This link offers a Direct, secure, fast & reliable digital transmission of both voice & data. (Cable replacement) by enabling a standardized wireless communication between any electrical device, Bluetooth has created the notion of a personal area network, a kind of close range wireless network that looks set to revolutionize the way people interact with information technology landscapes around them.

No longer do people need to connect, Plug into, install, enable, or configure anything to anything else. Through a ubiquitous standardized communication subsystem, devices will communicate seamlessly. One does not need to know where's one's cellular phone is, or even if it is switched on.

As soon as the web browser appears on the laptop computer screen, a link is established with the phone the Internet service provider is connected to, and the user is surfing the web. The Bluetooth specifications are open, global specification defining the complete system from radio right up to the application level. The protocol stack is usually implemented partly in hardware and partly as software running on a microprocessor, with different implementations partitioning the functionality between hardware and software in different ways

Why it is called Bluetooth?

Harald Bluetooth was king of Denmark in the late 900s. He managed to unite Denmark and part of Norway into a single kingdom then introduced Christianity into Denmark. He left a large monument, the Jelling rune stone, in memory of his parents. He was killed in 986 during a battle with his son, Svend Forkbeard. Choosing this name for the standard indicates how important companies from the Baltic region (nations including Denmark, Sweden, Norway and Finland) are to the communications industry, even if it says little about the way the technology works

Bluetooth strengths

1-Low Cost: with Bluetooth chips reaching 5$ each. And no licensing fees From Ericsson, as Ericcson set it for free

2- Tiny:

3- low-power consumption:

· 1 mW for class 3 (Range of 10 meters).

· 10 mW Extended Class 1(Range of 100 meters)

3 % of the power compared to that of the modern mobile

4-It works all over the world:

Operates on ISM radio band. (Industrial, Scientific & Medical band) Which is an :

Unlicensed band.

Globally available (2.4 GHz).

5-Supports point-to-point &Point-to-Multi point communication.

6- High Security: It allows authentication & encryption.

7- Protection against interference. : Uses frequency-hopping spread spectrum

Technology at 1600 hop/s

8-Support of Time critical Connections: By also supporting a Synchronous link ( in addition to The Asynchronous link)

Bluetooth's Origin

Bluetooth started in 1994, when Ericsson Mobile Communications began a study to examine alternatives to the cables that linked its mobile phones with accessories. The study looked at using radio links. Radio isn't directional, and it doesn't need line of sight, so it has obvious advantage over infrared links previously used between handsets and devices, there were many requirements for the study, including handling both speech and data, so that it could connect phones to headsets and computing devices.
Out of the study the Bluetooth specification was born. The specification is named after Harald Blatand (Blatand is Danish for Bluetooth) Harald was a tenth century Danish Viking King who united and controlled Denmark and Norway. The name was adopted because Bluetooth wireless technology is expected to unify the telecommunications and computing industries.

The Bluetooth SIG

The Bluetooth special interest group SIG is a group of companies working together to promote and define the Bluetooth specification. The following group of core promoters founded the Bluetooth SIG in February 1998

· Ericcson Mobile Communication

· Intel Corp.

· IBM Corp.

· Toshiba Corp.

· Nokia Mobile Phones.

Soon joined by

· Microsoft

· Lu cent

· 3Com

· Motorola

In May 1998, the core promoters publicly announced the global SIG and invited other companies to join the SIG as Bluetooth adopters in return for a commitment to support the Bluetooth specifications. the core promoters published version 1.0b of the Bluetooth specifications in July 1999.Now the number of companies Members in the SIG are over 2000 member.

The Bluetooth Physical Layer

Bluetooth devices operate at the 2.4 G Hz range in the globally available license free ISM band. This band is reserved for the general use by Industrial, Scientific, and Medical applications, which obey a basic set of power and spectral emission and interference specifications. This means the Bluetooth
has to be robust as there are a great many existing users and interferes of this shared spectrum. The operating band is divided into 1Mhz-spaced channels, each signaling data at 1MHz. The modulation scheme used is GFSK (Gaussian Frequency Shift Keying). After each packet, both devices re tune their radio to a different frequency, effectively hopping from channel to channel using an efficient Frequency Hopping Spread Spectrum technique. Each Bluetooth slot lasts 625 m sec. The radio power is one of three classes (1mW, 2,5mW and 100mW), which provide an operation that ranges of approximately 10 m, 20m, and 100; the lowest power gives 10 m range, and the highest power up to 100m.

Applications and Profiles

Bluetooth is aimed to produce convenient, reliable, cost effective, low power, short-range voice and data communications. At its most basic, Bluetooth wireless technology replaces a cable, this makes it suitable for short range connections between a varieties of mobile devices, such as:

· Mobile cellular phones to PSTN through an access point

· Mobile cellular phone to notebook PC

· Mobile cellular phone to a headset

· LAN access points for laptops and palmtops

· Communication between laptops and palmtops.

The Bluetooth specifications include a profiles document. Each profile describes how a particular application can be implemented. The specifications provide profiles for all of the connections listed above.

Uses:-

Bluetooth in the Office
As shown in Figure 7-1, all the devices in an office can form an ad hoc network whenever they come together. If the user wants to send a fax, the laptop will discover the presence of the fax machine, establish a connection, and send the fax. If the fax machine isn’t working, the laptop will know that fax service is not available. The user can bring his digital camera and download the picture on to the desktop and create a printout without connecting any cable. The user can synchronize the appointments stored in the laptop and mobile phone and ensure that both contain the same set of appointments for the next day.
The headset doesn’t need to be connected to the mobile phone through a wire to answer a call received on the phone. This is a typical Bluetooth office scenario

Bluetooth in the Home

Consider the PAN in the home shown in Figure 7-2. Just as with the PAN in the office, various devices can communicate with one another by using Bluetooth radio. Consider the following example, which illustrates the potential of this technology: When you go home, tired after a hard day’s work, you can put dinner in the microwave oven and relax in your living room while watching the TV. When dinner is done, the microwave oven will flash a message on the TV indicating that it’s time to eat. (Despite all the conveniences that Bluetooth affords, you still need to eat dinner with your own hands!) Perhaps this Bluetooth scenario has the potential of making you a couch potato, but this is just one example of the advantages of wireless networking in the home.

Bluetooth in the Car

fig7.3 The various gadgets in a car, such as a sound system, laptop, mobile phone, and headset, can be made to communicate with each other through Bluetooth. Someone sitting in the back seat can compose e-mail on the laptop and send the mail through the mobile phone without physically connecting the two. A person can hear the music emanating from the music system through the headphones, again without a wired connection.

As shown in Figure 7-3, the devices in the car will form a PAN or a personal operating space. If the car has a navigation system with a GPS (Global Positioning System) receiver, it can send the instructions to the driver on the headset without wires.