Tutoweb

Bluetooth Summary

A global standard that:

• eliminates wires and cables between both stationary and mobile devices

• facilitates both data and voice communication

• offers the possibility of ad hoc networks and delivers the ultimate synchronicity between all your personal devices

The Bluetooth wireless technology comprises hardware, software and interoperability requirements. It has been adopted not only by all major players in the telecom, computer and home entertainment industry, but also in such diverse areas as the automotive indus- try and health care, automation and toys, etc. - almost all sectors of the economy.

Harald Bluetooth

Harald Bluetooth was a Viking and king of Denmark between 940 and 981. One of his skills was to make people talk to each other, and during his rule Denmark and Norway were Christianized and united.

Today Bluetooth wireless technology enables people to talk to each other, but this time by means of a low-cost short-range radio link..

In the Danish town of Jelling Harald Bluetooth raised an enormous rune stone which still stands in its original posi- tion. It has the following runic inscription, adorned with an image of Christ: “King Harald raised this monument to the memory of Gorm his father and Thyre his mother, that

(same) Harald which won all Denmark and Norway and made the Danes Christian.” Originally the stone was painted.

In September 1999 a new stone was raised outside of Eric- sson Mobile Communications in Lund, this time to the memory of Harald Bluetooth

The First Steps

The idea that resulted in the Bluetooth wireless technology was born in 1994 when Erics- son 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 cum- bersome 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.

Beginners guide 1

The 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.

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 further development of the Specification still is one of the main issues for the SIG, other important tasks are interoperability require-

ments, frequency band harmonization and promotion of the technology. Learn more about the Bluetooth SIG at http://www.bluetooth.com/

Interoperability

From the very start one of the main goals for the SIG has been to include a regulatory framework in the Specification that will guarantee full interoperability between different devices from various manufacturers - as long as they share the same Profile.

While the usage models describe applications and intended devices, the Profiles specify how to use the Bluetooth protocol stack for an interoperable solution. In each Profile it is stated how to reduce options and set parameters in the base standard, how to use proce- dures from several base standards. A common user experience is also defined. For exam- ple, a computer mouse doesn’t need to communicate with a headset, and so they are built

to comply with different profiles.

The Profiles are a part of the Bluetooth Specification, and all devices must be tested against one or more of the Profiles in order to fulfil the Bluetooth certification require-

ments. The number of Profiles will continue to grow as new Bluetooth applications arise.

Compliance

The Bluetooth Qualification Program guarantees global interoperability between devices regardless of the vendor and regardless of the country in which they are used. During the test procedure which all devices must pass, it must be verified that they meet all require- ments regarding: radio link quality, lower layer protocols, profiles and information to

end-users. All qualified devices are listed at the SIG official website.

2 Beginners Guide

Usage Models

The profiles defined in version 1 of the Specification mainly address usage models con- cerning the telecom and computing industries.

Three examples are “Internet Bridge”, the “Ultimate Headset” and the “Automatic Syn- chronizer”.

An Internet bridge giving constant access to the Internet is a useful and time-saving fea- ture, especially when the bandwidth of mobile phones is increasing rapidly. Bluetooth wireless technology lets you surf the Internet without any cable connections wherever

you are, either by using a computer or by using the phone itself. When close to a wire- bound connection point, your mobile computer or handheld device can also connect directly to the land line, but still without cables.

The Ultimate Headset allows you to use your mobile phone even if it’s placed in a brief- case, thereby always keeping your hands free for more important tasks when you’re at the office or in your car.

Automatic synchronization of calendars, address books, etc. is a feature long-awaited for many of us. Simply by entering your office, the calendar in your phone or PDA will be automatically updated to agree with the one in your desktop PC, or vice versa. Phone numbers and addresses will always be correct in all your portable devices without dock-

ing through cables or infrared.

Bluetooth Products

Many companies have declared that Bluetooth wireless technology will be incorporated into their products, especially when components becomes cheaper. In a forecast made by Cahners In-Stat Group (July 2000), the product availability during the next couple of

years was defined as three waves.

The first wave is believed to occur around the turn of the year 2000/2001 and will include products like:

• Adapters for mobile phones and adapters (dongles) and PC Cards for notebooks and PCs

• High-end mobile phones and notebook PCs with integrated Bluetooth communication for the business users.

• Bluetooth headsets are expected to enter the market by the first half of 2001.

• Cordless phones, handheld PCs, and PDAs will also be included in this first wave. The first handheld PCs and PDAs are expected to enter the market during 2001.

The second wave will in many respects overlap the first. What we will see here is:

• PCs with Bluetooth circuitry on the motherboard.

• Printers, fax machines, digital still cameras, and products for industrial/medical and verti- cal industries will also begin to move in the second wave.

• There will be some industrial solutions that may become available as soon as the end of

2000 or 1Q2001.

• In the automotive sector the first Bluetooth options are expected to appear for the 2002

model year

(hands-free mobile phone usage with your regular mobile phone)

The third wave will include

• low-cost mobile phones and lower-cost portable devices and desktop PCs.

Beginners guide 3

Why Bluetooth wireless technology?

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 con- necting personal devices in Personal Area Networks (PAN). The demand for a system

that easily could connect devices for transfer of data and voice over a short distances - without cables, grew stronger.

Bluetooth wireless technology fill this important communication need, with its ability to communicate both voice and data wirelessly, using a standard low-power, low-cost tech- nology which can be integrated in all devices and thus enable total mobility. The price

will be low and result in mass production. The more units around, the more benefits for the customer.

The estimated Bluetooth chip market is shown below.

2500

Source: Merrill Ly

Chip market in volume by 2005

2000

1500

1000

500

0

2000 2001 2002 2003 2004 2005

Year

4 Beginners Guide

The Technology

The Bluetooth Specification defines a short (around 10 m) or optionally a medium range

(around 100 m) radio link capable of voice or data transmission to a maximum capacity of 720 kbps per channel.

Radio frequency operation is in the unlicensed industrial, scientific and medical (ISM)

band at 2.4 to 2.48 GHz, using a spread spectrum, frequency hopping, full-duplex signal

at up to 1600 hops/sec. The signal hops among 79 frequencies at 1 MHz intervals to give

a high degree of interference immunity. RF output is specified as 0 dBm (1 mW) in the

10m-range version and -30 to +20 dBm (100 mW) in the longer range version.

When producing the radio specification, high emphasis was put on making a design enabling single-chip implementation in CMOS circuits, thereby reducing cost, power consumption and the chip size required for implementation in mobile devices.

Voice

Up to three simultaneous synchronous voice channels are used, or a channel which simul- taneously supports asynchronous data and synchronous voice. Each voice channel sup- ports a 64 kb/s synchronous (voice) channel in each direction.

Data

The asynchronous data channel can support maximal 723.2 kb/s asymmetric (and still up

to 57.6 kb/s in the return direction), or 433.9 kb/s symmetric.

• a Master can share an asynchronous channel with up to 7 simultaneously active slaves in a

Piconet.

• by swapping active and parked slaves out respectively in the piconet, 255 slaves can be virtually connected using the PM_ADDR (a device can participate again within 2 ms).

• to park even more slaves the BD_ADDR can be used. There is no limitation to the number

of slaves that can be parked.

Slaves can participate in different piconets and a master of one Piconet can be the slave in another, this is known as a Scatternet. Up to 10 piconets within range can form a Scatter- net, with a minimum of collisions.

Beginners guide 5

Network Architecture

Bluetooth units that come within range of each other can set up ad hoc point-to-point and/

or point-to-multipoint connections. Units can dynamically be added or disconnected to the network. Two or more Bluetooth units that share a channel form a piconet.

Several piconets can be established and linked together in ad hoc scatternets to allow communication and data exchange in flexible configurations. If several other piconets are within range they each work independently and each have access to full bandwidth. Each piconet is established by a different frequency hopping channel. All users participating on the same piconet are synchronized to this channel. Unlike infrared devices, Bluetooth

units are not limited to line-of-sight communication.

To regulate traffic on the channel, one of the participating units becomes a master of the piconet, while all other units become slaves.With the current Bluetooth Specification up

to seven slaves can actively communicate with one master. However, there can be almost an unlimited number of units virtually attached to a master being able to start communi- cation instantly.

Scatternet

2 1

1

3 4 2

Piconet A Piconet B

Scatternet, ad-hoc combinations in a point-to-multipoint and point-to-point piconet.

6 Beginners Guide

Security

As radio signals can be easily intercepted, Bluetooth devices have built-in security to pre- vent eavesdropping or falsifying the origin of messages (spoofing).

The main security features are:

• a challenge-response routine - for authentication, which prevents spoofing and unwanted access to critical data and functions.

• stream cipher - for encryption, which prevents eavesdropping and maintains link privacy.

• session key generation - session keys can be changed at any time during a connection. Three entities are used in the security algorithms:

The Bluetooth device address (BD_ADDR/ 48 bits), which is a public entity unique for each device. The address can be obtained through the inquiry procedure.

A private user key (128 bits), which is a secret entity. The private key is derived during initialization and is never disclosed.

A random number (128 bits), which is different for each new transaction. The random number is derived from a pseudo-random process in the Bluetooth unit.

In addition to these link-level functions, frequency hopping and the limited transmission range also help to prevent eavesdropping.

Hardware Architecture

The Bluetooth hardware consists of an analog radio part and a digital part - the Host Con- troller. The Host Controller has a hardware digital signal processing part called the Link Controller (LC), a CPU core and interfaces to the host environment.

The Link Controller consists of hardware that performs baseband processing and physical layer protocols such as ARQ-protocol and FEC coding. The function of the Link Controller includes Asynchronous transfers, Synchronous transfers, Audio coding and Encryption.

The CPU core allows the Bluetooth module to handle Inquiries and filter Page requests without involving the host device. The Host Controller can be programmed to answer cer- tain Page messages and authenticate remote links.

The Link Manager (LM) software runs on the CPU core. The LM discovers other LMs

and communicates with them via the Link Manager Protocol (LMP) to perform its service provider role and to use the services of the underlying Link Controller.

Ericsson offers complete packages of intellectual property (IP) that support both Blue- tooth core and Bluetooth radio chip development.

Host Interface

External

Bluetooth Host Controller

Link Manager

CPU

Link

Radio

2.4 GHz

RF LINK

interfaces

core

Controller (LC)

Interface

Bluetooth Radio

Beginners guide 7

Software Architecture

The Bluetooth protocols are marked with blue color in the illustration below. In order to make different hardware implementations compatible, Bluetooth devices use the Host Controller Interface (HCI) as a common interface between the Bluetooth host (e.g. a por- table PC) and the Bluetooth core.

Higher level protocols like the Service Discovery Protocol (SDP), RFCOMM (emulating

a serial port connection) and the Telephony Control protocol (TCS) are interfaced to base- band services via the Logical Link Control and Adaptation Protocol (L2CAP). Among

the issues L2CAP takes care of, is segmentation and reassembly to allow larger data packets to be carried over a Bluetooth baseband connection.

The service discovery protocol allows applications to find out about available services and their characteristics when e.g. devices are moved or switched off.

Ericsson offers a generic software stack that includes HCI Driver, L2CAP, RFCOMM

and SDP to be integrated in a host environment.

vCard/

vCalendar

OBEX

WAE

WAP

AT Commands

UDP TCP

IP

PPP

RFCOMM

SDP TCS

L2CAP

HCI

LMP

Baseband

8 Beginners Guide

Competing Technologies

There is no single competitor covering the entire concept of the Bluetooth wireless tech- nology but in certain market segments other technologies exists.

For cable replacement the infrared standard IrDA has been around for some years and is quite well known and widespread. IrDA is faster than the Bluetooth wireless technology but is limited to point-to-point connections and above all it requires a clear line-of-sight.

In the past IrDA has had problems with incompatible standard implementations, a lesson that the Bluetooth SIG has learnt.

Two other short-range radio technologies using frequency hopping technique resides in the 2.4 GHz band:

Wireless LANs based on the IEEE 802.11 standard. The technology is used to replace a wired LAN throughout a building. The transmission capacity is high and so is the number

of simultaneous users. On the other hand it is, compared to Bluetooth wireless technol- ogy, more expensive, power consuming and the hardware requires more space and it is therefore not suited for small mobile devices.

The other 2.4 GHz radio is Home RF which has many similarities with the Bluetooth wireless technology. Home RF can operate ad hoc networks (data only) or be under the control of a connection point coordinating the system and providing a gateway to the tele- phone network (data & voice). The hop frequency is 8 Hz while a Bluetooth link hops at

1600 Hz.

Ultra-Wideband Radio (UWB) is a new radio technology still under development. Short pulses are transmitted in a broad frequency range. The capacity is indicated to be high while power consumption is expected to be low.

Licensing

Ericsson developed Bluetooth wireless technology. Now we license our Bluetooth chip solutions through packages of intellectual property, which comprises hardware and soft- ware in the form of the Bluetooth Core Product, the Bluetooth Host Stack and the Bluetooth Radio. Thus Ericsson is able to deliver total Bluetooth solutions to promote faster product time to market.

To support our intellectual property products we offer training, educational material and a full range of development tools.

Bluetooth products and services

Bluetooth intellectual property from Ericsson that can be used in products is aimed at three prime customer groups:

• High-volume silicon manufacturers/vendors,

• OEMs that are able to develop and implement their own solutions for Bluetooth devices,

• OEMs that require total Bluetooth solutions to match their product demands.

Beginners guide 9