Abstract and full paper on BLUETOOTH TECHNOLOGY

BLUETOOTH TECHNOLOGY

ABSTRACT

Bluetooth technology unplugs our digital peripherals and makes a cable clutter a thing of the past. In short, it is a wireless replacement for many of the cables we currently use to transmit voice and data signals. It is the result of the joint achievements of nine leading companies:  3COM, Lucent Technologies, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba, Ericsson, altogether known as the Blue Tooth Special Interest Group (SIG). The idea is to create a single wireless protocol to address the end-user problems arising from proliferation of various mobile devices.

The Bluetooth specification is ideal for mobile professionals who need to link notebook computers, mobile phones, PDA’s , PIMs, digital cameras, and other hand-held devices to do business at home, on the road, or in the office. Governments worldwide regulate it, so it is possible to utilize the same standard wherever one travels. Bluetooth provides three low power modes to conserve battery life: sniff mode, hold mode, and park mode. It aims at low power consumption and provides security for both stationary and mobile devices. A

Bluetooth chip (9mm x 9mm) takes the information normally carried by the cable, and transmits it at a special frequency to a receiver. Bluetooth radio modules use Gaussian Frequency Shift Keying (GFSK) for modulation. Blue Tooth employs an FHSS spreading technique, changing frequencies at a rate of 1600 times per second - 160 times the rate at which a wireless LAN changes frequencies. This provides a fairly robust communications link for its intended range. Signals can be transmitted through walls and briefcases, thus eliminating the need for line-of-sight.

Bluetooth is a standard developed that allows any sort of electronic equipment –from cellphones to keyboards and headphones-to make its own connections without direct action from a user. Bluetooth is primarily a wireless personal area networking technology, complementing other solutions (such as the industry-standard IEEE 802.11 and 802.11b based LANs).  Bluetooth is emerging as the short-range connection media of choice amongst mobile devices and electronic equipment, giving the user, ease of operation.    It promises to significantly change the way we use machines!!!

Introduction:

A look around at the moment! Keyboard connected to the computer, as well as a printer, mouse, monitor and so on. What (literally) joins all of these together? They are connected  by cables. Cables have become the bane of many offices, homes etc. That is what the Bluetooth technology aims at – a cable replacement technology!

Bluetooth - In detail:

One of the most significant recent developments in wireless technologies is the emergence of Wireless personal area networking (WPAN). Developed in 1998, WPAN is based on a new technology called Bluetooth, which uses short-range radio frequencies to transmit both voice and data. This technology wirelessly and transparently synchronizes data across devices and creates access to networks and the Internet within a range of ten meters. The short-range networks Bluetooth enables are called Personal Area Networks (PANs) or piconets. Bluetooth is more able to move from frequency to frequency, making it better able to handle interference than competing protocols. Bluetooth technology is the result of the joint achievements of nine leading companies:  3com, lucent technologies, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba, Ericsson altogether known as the Blue Tooth Special Interest Group (SIG), which has widespread participation by many companies. Originally initiated by L M Ericsson, it was designed as a short-range communications medium for wireless headsets to communicate with cellular phones.

Bluetooth technology Features:

            It separates the frequency band into hops. This spread spectrum is used to hop from one channel to another, which adds a strong layer of security.

            Signals can be transmitted through walls and briefcases, thus eliminating the need for line-of-sight. Devices do not need to be pointed at each other, as signals are omni-directional.

            Both synchronous and asynchronous applications are supported, making it easy to implement on a variety of devices and for a variety of services, such as voice and Internet.

            Governments worldwide regulate it, so it is possible to utilize the same standard wherever one travels.

The Aim of "Bluetooth" has been set quite high. It is to arrive at a specification for a technology that optimizes the usage model of all mobile computing and communications devices, and providing:

            Global usage ,Voice and data handling.

            The ability to establish ad-hoc connections.

            The ability to withstand interference from other sources in open band

            Very small size, in order to accommodate integration into variety of devices with negligible power consumption in comparison to other devices for similar use.

            An open interface standard and competitively low cost of all units, as compared to their non-Bluetooth correspondents.

BLUETOOTH is used in Phones and pagers and Headsets, Modems and LAN access devices , Notebook computers , Desktop and handheld computers, Printers and Fax machines, Keyboards and Joysticks.

Bluetooth Specification:

Bluetooth is a global specification for a small form-factor, low-cost radio solution providing links between mobile computers, mobile phones, and other portable handheld devices, as well as connectivity to the Internet. The Institute of Electrical and Electronics Engineers (IEEE) has given the IEEE 802.15 standard. A Time-Division Duplex (TDD) scheme is used for full-duplex transmission. Its main strength is its ability to simultaneously handle both data and voice transmissions. A mobile computer equipped with Bluetooth technology, for example, could link to a similarly equipped mobile phone to connect to the Internet. Multiple Bluetooth units form a Wireless Personal Area Network, called and up to seven client devices. A Bluetooth WPAN is capable of supporting an asynchronous data link with

each client and synchronous voice links with up to

three client devices. It provides a range of up to 10m

at a transmit power of 1 mwatt. The range can be

extended to 100m if the transmit power is increased to 100 mwatt. Bluetooth has a data rate of 1 Mbps. Bluetooth is a standard for a small (9mm  x 9mm) , cheap radio chip to be plugged into computers, printers, mobile phones, etc. A Bluetooth chip  takes the information normally carried by the cable, and transmits it at a special frequency to a receiver. Bluetooth chip, which will then give the information received to the computer, phone whatever. Bluetooth offers the most economical solution for low-to-medium-speed device connectivity. It aims at low power consumption and provides security for both stationary and mobile devices. The basic function is to provide a standard wireless technology to replace the multitude of propriety cables currently linking computing devices.

Technical standards and performance levels

1.         Bluetooth is based upon small, high performance integrated radio transceivers, each of which is allocated a unique 48-bit address derived from the IEEE 802 standards.

2.         It operates in the unrestricted 2.45 GHz ISM "free band", which is available globally, although slight variation of location and width of band apply.

3.         The range is set at 10 meters to optimize for target market of mobile and business user. The range can, however, be increased.

4.         Gross data rate is 1Mbit/s, with second generation plans to increase to 2 Mbit/s. One-to-one connections allow maximum data transfer rate of 721 kbits/s (corresponding to 3 voice channels).

5.         Bluetooth uses a packet switching protocol, based on a frequency hop scheme with 1600 hops/sek.  to enable high performance in noisy radio environments. The entire available frequency spectrum is used with 79 hops of 1 Mhz bandwidth, analogous to the IEEE 802.11 standard.

6.         It has low power consumption, drawing only 0.3 mA in standby mode. This enables maximum performance longevity for battery powered devices. During data transfer the maximum current drain is 30 mA. However, during pauses or at lower data rates the drain would be lower.

The Bluetooth Network Topology:

There are 3 types of connections in Bluetooth, as shown below:

Either: Single-slave  or  Multi-slave (up to 7 ”slaves”

 on one master)  or Scatternet. Multiple Bluetooth

units form a Wireless Personal Area  Network,

called a piconet.  A piconet consists of one hub device and up to seven client devices. It is possible to support more devices in a piconet by placing one or more of the clients into what is referred to as park mode. In order to exchange information with the parked client, the hub must take it out of parked mode and return it to active mode. Only seven clients can be in active mode at any given time. When two piconets are in close proximity, they have overlapping coverage areas - a scenario referred to as a scatternet Clients in one piconet can participate in another piconet as either a hub or client. This is accomplished through time

division on multiplexing. In a scatternet, the two

(or more) piconets are not synchronized in either

 time or frequency. Each of the piconets operates in its own frequency-hopping channel, while any devices in multiple piconets participate at the appropriate time via time division multiplexing. A piconet can be created in one of 4 ways: A page (used by Master to connect to Slave)  or A page scan (a unit listens for its´ device access code)  or A Master – Slave switch is made or An ”Unpark” of a unit is made (provided there are no active slaves).

Personal Networking Hardware And the Protocol Stack Layers:

Bluetooth radio modules use Gaussian Frequency Shift Keying (GFSK) for modulation. The data is transmitted at a data rate of 1 Mb/second.

The Bluetooth Baseband Layer: The baseband layer performs functions like Bluetooth packet assembly, forward error correction (FEC), automatic repeat request (ARQ), data whitening, Bluetooth clock synchronization, and frequency hopping control.

The Bluetooth Link Manager Layer: The Link Manager forms the piconet by inquiring what other Bluetooth radios are in the area, establishing connection and maintaining the piconet. The Link Manager also handles security issues like authentication and encryption.

Radio: The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2.4 GHz ISM band.

Base band: This layer describes the specification of the Bluetooth Link Controller (LC) which carriesout the baseband protocols and other low-level link routines.The Link Manager Protocol (LMP) is used by the Link Managers (on either side) for link set-up and control.The Host Controller Interface (HCI) provides a command interface to the Baseband Link Controller and Link Manager, and access to hardware status and control registers.

.Logical Link Control and Adaptation Protocol (L2CAP) supports higher

level protocol multiplexing, packet

segmentation and reassembly, and the

conveying of quality of service information.

L2CAP, which adapts upper layer protocols

over the Baseband, provides data services to the high layer protocols with group abstractions. The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol. The protocol is based on the ETSI standard TS 07.10. The Service Discovery Protocol (SDP) provides a means for applications to discover which services are provided by or available through a Bluetooth device. Device information, services and the characteristics of the services can be queried using the SDP.

The Power Modes:

Bluetooth provides for three low power modes to conserve battery life: sniff mode, hold mode, and park mode. While in the sniff mode, a device listens to the piconet at a reduced rate. The sniff interval is programmable, providing flexibility for different applications. In hold mode, only an internal timer is running, and data transfer restarts when units transition out of the hold mode. Park mode is used to handle more than seven clients - since only seven clients can be “active” at any time, one client can be “parked” and another one activated.

The advantage of   “frequency-hopping”

Bluetooth has been designed to operate in noisy radio frequency environments, and uses a fast acknowledgement and frequency-hopping scheme to make the link robust, communication-wise. 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 is because short packages and fast hopping limit the impact of microwave ovens and other sources of disturbances. Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links.  Bluetooth can support an asynchronous data channel, or up to 3 simultaneous synchronous voice channels, or a channel which simultaneously supports asynchronous data and synchronous voice.

Safer transmission of data: “Security”:

Bluetooth has built in sufficient encryption and authentication and is thus very secure in any environment. In addition to this, a frequency-hopping scheme with 1600 hops/sec. is employed. This is far quicker than any other competing system. This, together with an automatic output power adaption to reduce the range exactly to requirement, makes the system extremely difficult to eavesdrop. The transmitting power is far too weak to be noticeable for humans.

 Moreover, the radiation is not concentrated in a beam, but dispersed more or less in all directions. Hence not dangerous!!

Bluetooth units often have to contend with electro-magnetically noisy environments. Thus, the need for some kind of error-detection and -correction.  When errors are detected, there are 3 error-correction schemes defined for Bluetooth: 1/3 rate FEC (Forward Error Correction) , 2/3 rate FEC , ARQ unnumbered scheme (Automatic Repeat Request).

In Bluetooth, it has these components: Random Number Generation, Encryption,  Encryption Key Management 

and Authentication.In fig. On

 2 occasions, the transmitted

 data blocks gets corrupted,

which is detected by the

 recipient. So the next time that recipient gets a chance to communicate with that sender , the recipient sends a Negative Acknowledgement (a NAK, depicted in red), which prompts the other party to re-transmit that data block.

Application Examples:

1.         A Bluetooth-mouse or a Bluetooth-keyboard could be used at a further distance from a monitor, and while moving about in the room. 

2.         Use e-mail while your portable PC is still in the briefcase! When your portable PC receives an e-mail, you'll get an alert on your mobile phone.

3.         A travelling businessman could ask his laptop computer to locate a suitable printer as soon as he enters a hotel lobby, and send a printout to that printer when it has been found, and replied in a positive manner.

4.         Cable-less connection to printers and faxes, to digital cameras and video projectors. Cordless connection from cell phone to handsfree headset.

5.         Bluetooth interface to office PBX and Dial-up networking and automatic e-mail and use cell phone as office cordless phone. Use of PC or PDA as handsfree phone.

6.         Automatic exchange of files, electronic business cards, calendars etc.

Conclusion:

Despite some of the problems, Bluetooth remains a very promising technology, with plenty of medium and long term applications. But the real test will be whether it survives the hype. Promoters are laying on it, with their unrealistic claims.

This technology is probably the only one which has a good chance to become widely available among PDAs and mobile devices. Bluetooth-equipped gadgets can connect to the LAN through the Access Protocols at once.50 kilobytes per second is about all you can expect from Bluetooth. So there we are: Bluetooth is simply the best !!

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