24-11-2012, 04:34 PM
Bluetooth
Bluetooth1.doc (Size: 40.5 KB / Downloads: 28)
Abstract
The name Bluetooth came originally from a Danish Viking and King, Harald Blåtand (Bluetooth in English), who lived in the latter part of the 10th century. Harald Blåtand united and controlled Denmark and Norway (hence inspiration on the name : uniting devices through Bluetooth). Old Harald had a inclination towards eating Blueberries, so much so his teeth became stained with the color, leaving Harald with a rather unique set of molars
Bluetooth wireless technology is a specification designed to enable wireless communication between small, mobile devices. Functionally, Bluetooth is no different than a physical cable. The key difference is that Bluetooth uses a radio link to connect devices instead of a cable. From that end, Bluetooth is an enabling technology and not an application. The inspiration behind this technology was the desire to eliminate the need for proprietary cables, which are currently required to enable device connectivity. For instance, in order to transfer images from a digital camera to a laptop PC, a cable is needed in order to connect the camera to the laptop. Each camera manufacturer and model has a different cable requirement. In fact every hand held device manufactured which allows connectivity with a PC has a different cable configuration. Imagine a scenario in which both the laptop PC and the digital camera use Bluetooth wireless technology. In this case there is no need for cables to transfer data between devices. Instead, the data can be trasferred over a radio link. Expanding that idea to include all hand held mobile electronic devices is, in a nutshell, the Bluetooth wireless technology visiBluetooth, conceived initially by Ericsson before promoted by IBM, Intel, Nokia and Toshiba, is the code name for an open specification for short-range wireless connectivity. The technology allows users to make effortless, instant connections between a wide range of communication devices.
A Bluetooth chip is designed to replace cables by taking the information normally carried by the cable, and transmitting it at a special frequency to a receiver Bluetooth chip, which will then give the information received to the computer, phone, PDA whatever.
Bluetooth in a Nutshell
Bluetooth wireless technology is a specification designed to enable wireless communication between small, mobile devices. The inspiration behind this technology was the concept to eliminate the need for proprietary cables, which are currently required to enable device connectivity. For instance, in order to transfer images from a digital camera to a laptop PC, a cable is needed in order to connect the camera to the laptop. Each camera manufacturer and model has a different cable requirement. In fact every hand held device manufactured which allows connectivity with a PC has a different cable configuration. Imagine a scenario in which both the laptop PC and the digital camera use Bluetooth wireless technology. In this case there is no need for cables to transfer data between devices. Expanding that idea to include all hand held mobile electronic devices is, in a nutshell, the Bluetooth wireless technology vision.
The Bluetooth Family Tree
While Bluetooth wireless technology has many features unique to its own specification, it has borrowed heavily from several existing wireless standards, including Motorola's Piano, IrDA, IEEE 802.11, and Digital Enhanced Cordless Telecommunications (DECT). Motorola's Piano was developed with the concept of forming ad hoc "Personal Area Networks." This concept was adopted by the Bluetooth SIG to expand the capabilities of the original Bluetooth concept beyond simple cable replacement. The voice data transmission capabilities of Bluetooth are derived from the DECT specification. The object exchange capabilities (the ability to share business card, contact information, messages, etc.) are derived from the IrDA specifications. Bluetooth also inherits the use of the 2.4GHz ISM band, Frequency Hopping Spread Spectrum (FHSS), authentication, privacy, power management, and LAN capabilities provided by the IEEE 802.11 specification
Bluetooth Wireless Solution Components
There are four major components in any Bluetooth wireless technology system: a radio unit, a baseband unit, a software stack, and application software. The radio unit is the actual radio transceiver which enables the wireless link between Bluetooth devices. The baseband unit is hardware, consisting of flash memory and a CPU, which interfaces with the radio unit and the host device electronics at the hardware level. The baseband hardware provides all required functionality to establish and maintain a Bluetooth wireless connection between devices. The software stack is essentially driver software or firmware which enables the application level software to interface with the baseband unit. The application software implements the user interface and overall functionality of the Bluetooth
Bluetooth Radio
The Bluetooth wireless interface is enabled via a radio transceiver which operates within the 2.4 GHz ISM band. The Bluetooth Radio specification complies with United States FCC as well as international regulations on power output within the ISM band. Bluetooth Radio supports spectrum spreading which allows operation at power levels up to 100mW worldwide. Spectrum spreading is accomplished by frequency hopping in 79 hops displaced by 1 MHz, starting at 2.402 GHz and stopping at 2.480 GHz. The maximum frequency hopping rate is 1600 hops/s. Due to regulations in France[1], and Spain the number of hops is reduced which limits the allowed frequency spectrum of operation within those countries. These special case situations are handled by an internal software switch which limits the number of frequency hops used by the radio unit. The nominal link range between Bluetooth wireless devices is 10 centimeters to 10 meters, but may be extended to more than 100 meters by increasing transmit power or by taking advantage of the supported Bluetooth Baseband network topology
Bluetooth Baseband
A more proper term for this section would be 'Link Control Unit'. Within the Bluetooth Specification, the Link Controller (LC) is the actual hardware unit which enables the physical RF link between Bluetooth devices and implements baseband protocols and Link Manager (LM) routines. The LM routines enable setup and control of links between between devices; and provide the host terminal interface which is allows the host device to use a Bluetooth wireless connection.
Connection Establishment
All Bluetooth devices are in standby mode by default. In standby mode, unconnected devices periodically listen for messages. This procedure is called scanning. Scanning is divided into two types, page scan and inquiry scan. Page scan is defined as the connection substate in which a device listens for its own device access code (DAC) for duration of the scan window (11.25 ms) and is used to set up an actual connection between devices. Inquiry scan is very similar to page scan except that in this substate the receiving device scans for the inquiry access code (IAC). Inquiry scan is used to discover which units are in range and what their device addresses and clocks are. Following a successful scanning procedure one of four possible connection states is possible which include: active, hold, sniff, and park. If the scanning procedure was unsuccessful or a connection is not desired by one or both of the devices no connection is made.
Page Scan, Page, and Page Response
During the page scan procedure a device assumes either the role of the master or of the slave. The device that is the slave unit wakes up every 11.25ms (scan window) to listen for its DAC. The scanning done by the slave unit is done on one frequency hop sequence which is determined by the hardware within the unit. The potential master unit scans using a page train. The page train is a way for the unit to cover all 32 possible frequency hops[2] and to locate the slave unit which is listening on only one of those hops. Every 1.28 seconds a different frequency hop is scanned by the master unit. It should be noted that the page train scheme actually involves two page trains. Train A covers half the number of possible frequency hops while Train B covers the other half. Train A is used by default but if no devices are found during an exhaustive search of those frequency hops Train B will be scanned.
Bluetooth1.doc (Size: 40.5 KB / Downloads: 28)
Abstract
The name Bluetooth came originally from a Danish Viking and King, Harald Blåtand (Bluetooth in English), who lived in the latter part of the 10th century. Harald Blåtand united and controlled Denmark and Norway (hence inspiration on the name : uniting devices through Bluetooth). Old Harald had a inclination towards eating Blueberries, so much so his teeth became stained with the color, leaving Harald with a rather unique set of molars
Bluetooth wireless technology is a specification designed to enable wireless communication between small, mobile devices. Functionally, Bluetooth is no different than a physical cable. The key difference is that Bluetooth uses a radio link to connect devices instead of a cable. From that end, Bluetooth is an enabling technology and not an application. The inspiration behind this technology was the desire to eliminate the need for proprietary cables, which are currently required to enable device connectivity. For instance, in order to transfer images from a digital camera to a laptop PC, a cable is needed in order to connect the camera to the laptop. Each camera manufacturer and model has a different cable requirement. In fact every hand held device manufactured which allows connectivity with a PC has a different cable configuration. Imagine a scenario in which both the laptop PC and the digital camera use Bluetooth wireless technology. In this case there is no need for cables to transfer data between devices. Instead, the data can be trasferred over a radio link. Expanding that idea to include all hand held mobile electronic devices is, in a nutshell, the Bluetooth wireless technology visiBluetooth, conceived initially by Ericsson before promoted by IBM, Intel, Nokia and Toshiba, is the code name for an open specification for short-range wireless connectivity. The technology allows users to make effortless, instant connections between a wide range of communication devices.
A Bluetooth chip is designed to replace cables by taking the information normally carried by the cable, and transmitting it at a special frequency to a receiver Bluetooth chip, which will then give the information received to the computer, phone, PDA whatever.
Bluetooth in a Nutshell
Bluetooth wireless technology is a specification designed to enable wireless communication between small, mobile devices. The inspiration behind this technology was the concept to eliminate the need for proprietary cables, which are currently required to enable device connectivity. For instance, in order to transfer images from a digital camera to a laptop PC, a cable is needed in order to connect the camera to the laptop. Each camera manufacturer and model has a different cable requirement. In fact every hand held device manufactured which allows connectivity with a PC has a different cable configuration. Imagine a scenario in which both the laptop PC and the digital camera use Bluetooth wireless technology. In this case there is no need for cables to transfer data between devices. Expanding that idea to include all hand held mobile electronic devices is, in a nutshell, the Bluetooth wireless technology vision.
The Bluetooth Family Tree
While Bluetooth wireless technology has many features unique to its own specification, it has borrowed heavily from several existing wireless standards, including Motorola's Piano, IrDA, IEEE 802.11, and Digital Enhanced Cordless Telecommunications (DECT). Motorola's Piano was developed with the concept of forming ad hoc "Personal Area Networks." This concept was adopted by the Bluetooth SIG to expand the capabilities of the original Bluetooth concept beyond simple cable replacement. The voice data transmission capabilities of Bluetooth are derived from the DECT specification. The object exchange capabilities (the ability to share business card, contact information, messages, etc.) are derived from the IrDA specifications. Bluetooth also inherits the use of the 2.4GHz ISM band, Frequency Hopping Spread Spectrum (FHSS), authentication, privacy, power management, and LAN capabilities provided by the IEEE 802.11 specification
Bluetooth Wireless Solution Components
There are four major components in any Bluetooth wireless technology system: a radio unit, a baseband unit, a software stack, and application software. The radio unit is the actual radio transceiver which enables the wireless link between Bluetooth devices. The baseband unit is hardware, consisting of flash memory and a CPU, which interfaces with the radio unit and the host device electronics at the hardware level. The baseband hardware provides all required functionality to establish and maintain a Bluetooth wireless connection between devices. The software stack is essentially driver software or firmware which enables the application level software to interface with the baseband unit. The application software implements the user interface and overall functionality of the Bluetooth
Bluetooth Radio
The Bluetooth wireless interface is enabled via a radio transceiver which operates within the 2.4 GHz ISM band. The Bluetooth Radio specification complies with United States FCC as well as international regulations on power output within the ISM band. Bluetooth Radio supports spectrum spreading which allows operation at power levels up to 100mW worldwide. Spectrum spreading is accomplished by frequency hopping in 79 hops displaced by 1 MHz, starting at 2.402 GHz and stopping at 2.480 GHz. The maximum frequency hopping rate is 1600 hops/s. Due to regulations in France[1], and Spain the number of hops is reduced which limits the allowed frequency spectrum of operation within those countries. These special case situations are handled by an internal software switch which limits the number of frequency hops used by the radio unit. The nominal link range between Bluetooth wireless devices is 10 centimeters to 10 meters, but may be extended to more than 100 meters by increasing transmit power or by taking advantage of the supported Bluetooth Baseband network topology
Bluetooth Baseband
A more proper term for this section would be 'Link Control Unit'. Within the Bluetooth Specification, the Link Controller (LC) is the actual hardware unit which enables the physical RF link between Bluetooth devices and implements baseband protocols and Link Manager (LM) routines. The LM routines enable setup and control of links between between devices; and provide the host terminal interface which is allows the host device to use a Bluetooth wireless connection.
Connection Establishment
All Bluetooth devices are in standby mode by default. In standby mode, unconnected devices periodically listen for messages. This procedure is called scanning. Scanning is divided into two types, page scan and inquiry scan. Page scan is defined as the connection substate in which a device listens for its own device access code (DAC) for duration of the scan window (11.25 ms) and is used to set up an actual connection between devices. Inquiry scan is very similar to page scan except that in this substate the receiving device scans for the inquiry access code (IAC). Inquiry scan is used to discover which units are in range and what their device addresses and clocks are. Following a successful scanning procedure one of four possible connection states is possible which include: active, hold, sniff, and park. If the scanning procedure was unsuccessful or a connection is not desired by one or both of the devices no connection is made.
Page Scan, Page, and Page Response
During the page scan procedure a device assumes either the role of the master or of the slave. The device that is the slave unit wakes up every 11.25ms (scan window) to listen for its DAC. The scanning done by the slave unit is done on one frequency hop sequence which is determined by the hardware within the unit. The potential master unit scans using a page train. The page train is a way for the unit to cover all 32 possible frequency hops[2] and to locate the slave unit which is listening on only one of those hops. Every 1.28 seconds a different frequency hop is scanned by the master unit. It should be noted that the page train scheme actually involves two page trains. Train A covers half the number of possible frequency hops while Train B covers the other half. Train A is used by default but if no devices are found during an exhaustive search of those frequency hops Train B will be scanned.