Bluetooth Overview Questions

Why is it called Bluetooth?
In 1998, a special interest group (SIG) was formed to develop and promote the technology. The SIG took the name Bluetooth from Harald II "Bluetooth" King of Denmark who was born in the 10th century. Bluetooth peacefully unified Denmark and Norway.

What is the Bluetooth SIG?
The Bluetooth SIG was formed as a group of companies working together to define, develop and promote an open, royalty-free specification for seamless wireless connectivity and cable replacement for a wide variety of mobility-enhancing devices.
In developing the Bluetooth specification, the SIG is strictly adhering to some basic principles that can be summed up in five key words: freedom, security, simplicity, versatility, and reliability. These key words are the foundation of Bluetooth.

Who are the members of the SIG?
The founding SIG members are Ericsson, Intel, IBM, Nokia, and Toshiba. Since then over 2000 adopter companies have joined including HP, Lucent, Motorola, and 3Com. Our company, IVT corporation, is Bluetooth SIG silver associate member.

What are the features of Bluetooth?
The features of Bluetooth are best described through the Bluetooth profiles specification. These profiles lay out the capabilities and usage models in an un-ambiguous fashion. Please see – “Supported Bluetooth Profiles”

Is there a Bluetooth standard?
The Bluetooth standard comes from the Bluetooth SIG. The IEEE has formed a working group called 802.15 that is looking to adopt Bluetooth.

Will Bluetooth products work only in certain areas of the world?
Bluetooth technology will work globally. It works in the globally available spectrum. However, the number of available channels is reduced for Spain, France, and Japan. The Bluetooth SIG is actively working with the various country authorities to harmonize the spectral allocation worldwide and good progress has already been made toward this goal.

How is Bluetooth technology going to be licensed? Is this technology royalty-free? Are there any patents or licenses involved?
Yes, there are several patents on different parts of the technology. Because of this all licensees will have to sign a zero cost license agreement to cover sharing of intellectual property and naming.

How does Bluetooth work?
Bluetooth uses a frequency hopping spread spectrum technique. Spectrum spreading is accomplished by frequency hopping up to 1600 hops per second on 79 channels between 2.402 GHz and 2.480 GHz.
Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a data packet. The sophisticated mode of transmission adopted in the Bluetooth specification ensures protection from interference and seeks to insure the security of the data.

In what frequency range do Bluetooth devices operate?
Bluetooth operates in the 2.4 GHz range referred to as the Instrumentation, Scientific, and Medical (ISM) band. This band provides license-free operation in the United States, Europe, Japan, and most industrialized nations worldwide.

How much power does Bluetooth transmit?
In the Bluetooth specification there are three classes of radios, which are characterized by their output power. Class 1 is specified to have a maximum transmit power of +20 dBm (100 milliwatts). Class 2 has a maximum transit power of +4 dBm (2.5 milliwatts). Class 3 has a maximum transmit power of 0 dBm (1 milliwatt).
The Bluetooth specification limits the radio output power exactly to that actually required. For instance, if the receiving radio indicates that it is only a few meters away, the transmitter immediately modifies its signal strength to suit the exact range.
This feature dramatically reduces the radio’s power consumption as well as its radio interference. Furthermore, the radio chip automatically shifts to a low-power mode as soon as traffic volumes becomes low or stops. The low-power mode is only interrupted by very short signals with the purpose of verifying the established connection.
The radio with Bluetooth wireless technology consumes less than a few percent of the power consumed with a modern mobile phone. The transmission mode is only used as necessary, and always for the shortest possible period of time.

Does Bluetooth support voice communication?
The Bluetooth specification calls for up to three synchronous voice channels of 64 Kbps, which are used in 4 profiles: Intercom, Cordless Telephony, Hands-Free and Headset. There is another profile, named Advanced Audio Distribution, which specialized at high quality stereo audio data.

What is the range of Bluetooth?
The link range is up to 10 meters using a 0 dBm radio. The range is extended up to 100 meters using a +20 dBm radio.

What is the transfer speed?
The gross data rate of Bluetooth 1.1 is 1 Mbps. The protocol splits that bandwidth to support both voice and data communication. Bluetooth can support an asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel, which simultaneously supports asynchronous data and synchronous voice. Each voice channel supports a 64 Kbps synchronous (voice) link. The asynchronous data channel can support an asymmetric link of up to 721 Kbps in either direction, while permitting 57.6 Kbps in the return direction or a symmetric link up to 432.6 Kbps.
The gross data rate of Bluetooth 2.0, the EDR version, is up to 3Mbps.

What is Enhanced Data Rate, EDR?
EDR provides a set of additional compact packet types which improves the Bluetooth radio bandwidth usage, so that Bluetooth data can be transferred in 2Mbps or 3Mbps mode.

Will Bluetooth devices from different manufacturers interoperate?
To be able to carry the Bluetooth name and Bluetooth logo on a product, manufacturers have to get their product tested and certified. This testing will help ensure that products interoperate.

How do Bluetooth devices communicate with each other?
The Bluetooth specification calls for devices to connect in an ad-hoc fashion into small Bluetooth networks called piconets. These piconets provide a bubble of connectivity around the user and are the basis for creating a personal area network.