Introduction:
Bluetooth is the codename for a technology specification for low-cost, short-range radio links between mobile PCs, mobile phones and other portable devices, and connectivity to the Internet. The Bluetooth wireless technology specification marks the first time that major players in the converging communications and computer industries have defined a radio standard that allows mobile phones, hand-held computers and PCs to communicate wirelessly with each other without manual intervention from the user. The specification's ability to meet cost/performance needs for a whole raft of applications will be a significant factor in its adoption. Bluetooth wireless technology is lower in cost than alternative wireless standards and will also often allow a lower cost replacement for cables and connectors, particularly when accounting for installation and maintenance. It is about to revolutionize the personal connectivity market by providing freedom from wired connections.
Bluetooth is a communication protocol that has been designed with the purpose of allowing devices to communicate freely without any reliance upon cabling. It has quickly become a key standard in the implementation of wireless networking between devices such as PDAs (Personal Data Assistants) and laptop computers. The key advantages that Bluetooth offers over other wireless networking protocols that have been implemented thus far (particularly in portable computing and communications), are that it does not require line of sight, and it is a low power protocol, that is battery equipped devices do not suffer excessive battery drain. Line-of-sight has been the major restriction of using infra-red as the medium of interdevice wireless networking. Thus, Bluetooth offers a tremendous marketing boost for the manufacturers of portable computing devices due to its convenience and ease of use. 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 (Muller, N.J., 2001).
It is 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
History:
Harald Bluetooth was a viking and King of Denmark between 940 and 981. One of his skills was getting people to talk to each other, and during his rule Denmark and Norway were christianized and united. Today, Bluetooth wireless technology enables devices 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 runestone which still stands in its original position. 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 Ericsson in Lund, this time to the memory of Harald Bluetooth.
The idea that resulted in the Bluetooth wireless technology was born in 1994 when Ericsson 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 of becoming a universal bridge for existing data networks, a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures.
In February 1998, the Special Interest Group (SIG) was formed. Today the Bluetooth SIG includes promoter companies Agere, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia and Toshiba, and thousands of Associate and Adopter 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 tasks for the SIG, other important ones being interoperability requirements, frequency band harmonization and promotion of the technology.
Uses of Bluetooth:
Bluetooth can be used in many ways. These are the basic uses of bluetooth:
* An Internet bridge giving constant access to the Internet is a useful and time-saving feature, 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 briefcase, thereby always keeping your hands free for more important tasks when you are 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 docking ...
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* The Ultimate Headset allows you to use your mobile phone even if it's placed in a briefcase, thereby always keeping your hands free for more important tasks when you are 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 docking through cables or infrared.
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 has been presented 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 - grows stronger, and unlike infrared devices, Bluetooth units are not limited to line-of-sight communication.
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.
How Bluetooth Works:
The Bluetooth Specification does not define what should be hardware and/or software. The following architecture solution is Ericsson's interpretation, one of the earliest and most stable implementations.
The Bluetooth hardware consists of an analog radio part and a digital part - the Host Controller. The Host Controller has a hardware digital signal processing part called the Link Controller (LC), a CPU core and interfaces to the host environment (Muller, N.J., 2001).
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 (Muller, N.J., 2001).
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 certain Page messages and authenticate remote links (Muller, N.J., 2001).
The Link Manager (LM) software runs on the CPU core. The LM discovers other LM's 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.
The Bluetooth Specification defines a short (around 10 meters) or optionally a medium range (around 100 meters) radio link capable of voice or data transmission up to a maximum capacity of 720 Kb/s per channel.
Radio frequency operation is in the unlicensed industrial, scientific and medical (ISM) band at 2.40 to 2.48 GHz, using a spread spectrum, frequency hopping, full-duplex signal at a nominal rate of 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 (Morrow, R. 2003).
When producing the radio specification, high emphasis was put on specifying a design that enables low cost, minimum power consumption and a small chip size required for implementation in mobile devices. As radio signals can be easily intercepted, Bluetooth devices have built-in security (explained later) to prevent eavesdropping or falsifying the origin of messages (Morrow, R. 2003).
A small Bluetooth microchip, incorporating a radio transceiver, is built into digital devices, such as a cell phone or mobile computer. Bluetooth makes these connections without any wire. It replaces the cables by taking information normally carried by cable, and transmitting it at a special frequency to a receiving Bluetooth. The purpose of Bluetooth is to have fast and secure transmissions of voice and data, even if devices are not next to each other. The Bluetooth specification has, "two power levels defined; a lower power level that covers the shorter personal area within a room, and a higher power level that can cover a medium range, such as within a home". The software is what controls and identifies the coding built into each microchip to ensure that only those units preset by their owners can communicate. Bluetooth is evolving due to companies that have merged together to create this communication system.
There are nine companies which are:
3Com, Ericsson, Nokia, Intel, IBM, Lucent, Microsoft, Motorola, Toshiba.
Ericsson initially conceived Bluetooth. Additionally, these companies are not the only one's that are now involved in bluetooth. Other manufactures from different parts of the world are joining Bluetooth.
The upper layers of 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 portable 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 baseband 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, for example, devices are moved or switched off.
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There is no single competitor covering the entire concept of the Bluetooth wireless technology but in certain market segments other technologies exist.
(Muller, N.J., 2001)
Comparing Bluetooth with other technologies:
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 have had problems with incompatible standard implementations, a lesson that the Bluetooth SIG has learnt.
Two other short-range radio technologies using frequency hopping technique reside in the 2.4 GHz band:
Wireless LAN's 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, compared to Bluetooth wireless technology, it is more expensive and power consuming, and the hardware requires more space. It is therefore not suitable for small mobile devices.
The other 2.4 GHz radio is Home RF, which has many similarities to 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 telephone 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 appears to be high while power consumption is expected to be low.
In 1994, Ericsson invented the short-range wireless technology which in 1998 became widely known by the Bluetooth name. Now we license our Bluetooth Cores, i.e. chip design and software solutions through packages of intellectual property. Our mission is to be the world-leading provider of intellectual property for Bluetooth wireless technology (Muller, N.J., 2001).
Using the Bluetooth Cores is the fastest way for a manufacturer to launch new products with a minimum of R&D spending and resources. Bluetooth wireless technology is a very complex system (Muller, N.J., 2001).
Advantages of Bluetooth:
Bluetooth can penetrate walls, briefcases, and other obstacles, and its omni directional (capable of transmitting or receiving signals in all directions, as an antenna). Even though the transmission range is only 30 feet, Bluetooth will let computers and handheld devices talk to each other without wires or cables. You will soon be able to synchronize the information in your cell phone with the database in your PalmPilot. Also, print photos directly from a digital camera. Moreover, use your cell phone as a modem for your laptop. Eventually, the technology could evolve to the point where consumers wearing a small Bluetooth-enabled device could shop by having their credit card information conveyed directly to the store's computer (Morrow, R. 2003).
Disadvantages of Bluetooth:
One of the things that may cause conflicts for Bluetooth is that it uses the same frequency as the Wavelan standard. Another problem for Bluetooth is when there are a number of mobile devices in the same room, and possibly attempting the same operation. Since Bluetooth is omni-directional, it encounters problems in discovering the intended recipient device. Bluetooth devices must perform a discovery operation that will likely find many other devices in the same room. At this point, the user must choose the proposed recipient, which will require special information. Furthermore, Bluetooth has so many security mechanisms that it would have to carry out in order to prevent eavesdropping. In addition, the transfer rate of bluetooth is considerably slow compared to other devices. Bluetooth can only muster 1Mbps, while IR (for example) can have data throughput rates of up to 4Mbps, which provides fast throughput for purposes such as file transfer (Brent A. Miller. 2002).
Bluetooth market:
The market for Bluetooth devices is subject to both hype and substance. Some analysts believe that the market has been damaged by Bluetooth devices that are released but do not conform fully to spec, resulting in compatibility problems. Other issues can be user software.. In Australia, Bluetooth devices are only now starting to hit the retail channel, and are becoming popular with executives and businessmen that need their communication problems simplified. This is nowhere more apparent than in the Mobile phone and PDA (Personal Data Assistant) market. The ability to check your email while on the go without even touching your phone is a very appealing prospect to the industry's target consumer. Bluetooth has also been designed from the outset to be a low cost option. For this reason Bluetooth is expected to achieve far greater unit volumes than other wireless standards. One of the drawbacks of Bluetooth that has seen it held back from the market to some extent is its compatibility with 802.11b wireless networking devices. These devices share the same frequency, which can result in unreliable communication. Given that the entire market is moving towards wireless networking, it presents a substantial marketing problem if Bluetooth and 802.11b cannot work in the same environment, since both devices are marketed towards the same corporate target. This problem is however being addressed by both the SIG and the IEEE (Institute of Electrical and Electronics Engineers) (Brent A. Miller. 2002).
Bluetooth Security:
Radio frequency transmissions are easily intercepted. Infra red communication between devices, being line-of sight and requiring two devices to be very close to each other for communication to take place, results in IR having a distinct security advantage. Data security is placed as a highly important requirement in the Bluetooth spec. The specification has defined three security levels
Mode 1: This refers to the absence of security when devices are transmitting non sensitive information. An example of this may be business card details. The link level security functions are bypassed at this level.
Mode 2: This provides service level security. This means that security takes place at a higher layer in the Protocol Stack. This results in security flexibility since different levels of security can be set by different applications that may be running simultaneously.
Mode 3: This is security set at one point, such that all communications are secure. This is done at the LMP layer. It is often called Link-level security. This kind of security is easier to implement than Mode 2. A key difference between Security Mode 2 and Security Mode 3 is that in Security Mode 2, the channel is first created and security procedures are then established, while in Security Mode 3 the channel is not established until security procedures have authorised it to be created.
The first time two devices communicate via Bluetooth, several security oriented procedures take place. An initialisation procedure called pairing occurs. This is used to create a common link key. A link key is used for both encryption and authentication. The first time this happens, authentication requires the user to enter a PIN number. This is then translated into a 128 bit link key. Once authentication takes place, communication is encrypted at up to 128 bits in length. This can vary to less than 128 bits in multiples of 8 bit length. This is negotiated between the Link Layers of the involved devices. This is important in international terms, since Bluetooth devices from other countries may not be able to encrypt up to the full 128 bit length that Bluetooth is capable of using, and thus the ability to negotiate a shorter key is mandatory. The Bluetooth authentication scheme is essentially a challenge-response technique. The protocol checks to see if the other device has the same key as itself, and if it does, authentication is successful. This happens in sequence as follows: 1. The verifier transmits to the claimant a random number to be authenticated. 2. Both the verifier and the claimant use the authentication function E1 with the RAND (random number), the claimant's BD_ADDR and the current link key to obtain a response. 3. A response to the verifier is made by the claimant. The verifier then makes sure the responses are a match (Brent A. Miller. 2002).
This application indicates who is to be authenticated. If the authentication fails, there is a period of time that must pass until a new attempt at authentication can be made. As an aid to ensure security, the waiting time grows exponentially for repeated authentication failures. It can reach the point where the claimant must leave the vicinity of the other device for a time until the authentication procedure is reset, and the process can begin again.
Three entities are used in the security algorithms:
The Bluetooth device address (48 bits), is a public entity unique for each device. The address can be obtained through the inquiry procedure.
A private user key (128 bits), is a secret entity. The private key is derived during initialization and is never disclosed.
A random number (128 bits), 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, the limited transmission range also help to prevent eavesdropping.
In short, 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.
Packet Encryption:
The Bluetooth encryption system systematically encrypts the payload of each packet. This is done with a stream cipher, which is re-synchronized for every payload. There are several encryption modes available (depending on whether a device uses a semi-permanent link key or a master key). If a unit key or a combination key is used, broadcast traffic is not encrypted. Point-to-point traffic can be either encrypted or not. If a master key is used, there are three possible modes.
ENCRYPTION MODE 1: In this mode, nothing is encrypted.
ENCRYPTION MODE 2: Point-to-multipoint (broadcast) traffic is not encrypted. However traffic that is point-to-point addressed is encrypted with the master key.
ENCRYPTION MODE 3: In this case, all traffic is encrypted with the master key.
In every application there is a defined minimum acceptable key size. If this minimum key size requirement is not met by either of the participants in the (encryption) key size negotiation , then the application aborts the negotiation and the encryption cannot be used. This is done because of the possibility that a malicious device could force a lower encryption setting, which would leave the device potentially open to attack/eavesdropping.
The Radio Technology:
As specified by Bluetooth, the basic radio to be used transmits 10 m in open air (although current implementations operate well at significantly better range), with an optional power level to allow 100-m operation. With a total bandwidth of 1 Mb/sec, the radio is designed for moderate speed and a theoretical 720 Kb/sec payload, dividing up the bandwidth among the devices using data and voice channels.
The Bluetooth radio was designed for immunity to noise and for ease of implementation on silicon, with major base and portions implemented in either hardware or firmware to optimise cost, power, and size.
To achieve robust connections, Bluetooth employs three key techniques: frequency hopping, adaptive power control, and the transmission of short data packets. The Bluetooth protocol (for data) automatically retransmits corrupt data packets that have-because the pseudorandom hopping sequence is designed to maximize frequency spacing between sequential channel hops-most likely hopped away from the interfering source.
Like other radio technologies, Bluetooth operates in the 2.4-2.485-GHz radio band. Its radio meets the power and spectral emissions specifications using the following set of parameters:
* Frequency hopping, spread spectrum 79 channels, 1600 hops per second.
* Gaussian frequency shift keying modulation with a 1-m symbol-per-second rate or 1 Mb/sec data rate.
* 83.5 MHz of spectrum divided into 1-MHz channels.
* Symbol timing accuracy ±20 ppm timing (when synchronized).
* Power control based on received signal strength intensity feedback from the receiving device (Class 1 requirement).
* 0 dBm (1 mW) without power control (Class 3, 10-m range).
* 20 dBm (100-mW) with power control (Class 1, 100-m range).
* Bit error rate of 0.1%, receiver sensitivity of -70 dBm.
Key Bluetooth features:
Bluetooth has been designed to facilitate setup of small groups of devices. Two key features, service discovery and ad hoc network support, also play major roles in the design, and security features protect the privacy of communications.
Service Discovery Protocol. Service discovery protocol (SDP) features allow for automatic recognition and configuration between two devices of different types and from different manufacturers.
There are two types of discovery within the Bluetooth specification. Device discovery allows one device to query devices within range and acquire, in turn, key information about their general capabilities. This key information includes full address, human-readable name, and general device type (cell phone, laptop personal computer, headset).
Service discovery enables a device to learn the details of supported profiles and to actually browse those profiles to find out how to access certain features. The service discovery concept allows for even more information and access methods to be exchanged.
Conclusion:
In conclusion, Bluetooth has many uses, which are Internet Bridge, Ultimate Headset and Automatic synchronization. While comparing with other devices, we concluded that Infrared transmission has to be point-to-point while is omni directional. As for the history, it was taken from a famous Viking named Herald Bluetooth. However, disadvantages arise when the security issue is bought in the topic
Reference List
* Muller, N.J., 2001, Bluetooth Demystified, McGraw Hill, New York
* Specification Volume 1 - Specification of the Bluetooth System
* http://www.palowireless.com/infotooth/
* www.bluetooth.com
* Morrow, R. 2003, Bluetooth operation and use
* Brent A. Miller. 2002, Bluetooth Revealed: The Insider's Guide to an Open Specification for Global Wireless Communications (2nd Edition)
* http://www.smarthomeforum.com/start/faq.asp?ID=3
