Bluetooth 2 | Enhanced Data Rate EDR | Tutorial
`
`News feed
`
`Newsletter
`
`Google+
`
` Twitter
`
`Search
`
`Home
`
`Navigation:: Home >> Wireless technologies >> this page
`
`Antennas & propagation
`
`Broadcast technology
`
`Cellular telecoms
`
`Circuit design
`
`Design principles
`
`Distribution & supply
`
`Electronic components
`
`Electronics manufacture
`
`Formulae & data
`
`Power management
`
`Processing & embedded
`
`RF topics & receivers
`
`Satellite technology
`
`Technology history
`
`Telecoms & networks
`
`Test & measurement
`
`Wireless technology
`
`News
`
`Events & exhibitions
`
`Bookshop
`
`Equipment shop
`
`Training & courses
`
`Jobs
`
`About us
`
`Privacy Policy
`
`Advertise with us
`
`Bluetooth 2 - Enhanced Data Rate, EDR
`
` - summary of Bluetooth Enhanced Data Rate, EDR detailing the upgrades to
` the Bluetooth specification that enables it to attained much higher data rates
` and improved performance.
`
`Bluetooth tutorial includes:
`
`• Bluetooth overview
`• Bluetooth 2 / EDR
`• Bluetooth 3
`• Bluetooth Low Energy / Wibree
`• Bluetooth radio interface & modulation
`• Bluetooth data file transfer
`• Bluetooth Host: L2CAP, GAP & SDP
`• Bluetooth profiles
`• Bluetooth network, connection & pairing
`• Bluetooth security
`
`Bluetooth EDR or Bluetooth 2 is an upgrade of
` the original Bluetooth specification. It based
` on the original Bluetooth standard which is
` well established as a wireless technology. It has found a very significant number of applications,
` particularly in areas such as connecting mobile or cell phones to hands-free headsets.
`
`One of the disadvantages of the original version of Bluetooth in some applications was that the
` data rate was not sufficiently high, especially when compared to other wireless technologies such
` as 802.11. In November 2004, a new version of Bluetooth, known as Bluetooth 2 was ratified.
` This not only gives an enhanced data rate but also offers other improvements as well.
`
`Of all the features included in Bluetooth 2, it is the enhanced data rate (EDR), facility that is giving
` rise to the most comment. In the new specification the maximum data rate is able to reach 3
` Mbps, a significant increase on what was available in the previous Bluetooth specifications.
`
`Why is Bluetooth 2 needed?
`As proved particularly by the computer industry, there is always a need for increased data rates,
` and ever increasing capacity. With this in mind and the fact that the previous version of
` Bluetooth, version 1.2 allowed a maximum data rate of 1 Mbps which reflected in a real
`throughput of 723 kbps, the next specification should allow many new applications to be run. In
` turn this will open up the market for Bluetooth even more and allow further application areas to
` be addressed.
`
`While speed on its own opens up more opportunities, the strategy behind Bluetooth 2 with its
` enhanced data rate is more deep rooted. When the Bluetooth 2 specification was released there
` were no applications that were in immediate need of the new enhanced data rate. For example
`even a high quality stereo audio stream required a maximum of only 345 kbps.
`
`The reason is that as Bluetooth use increases, and the number of applications increase, that users
` will need to run several links concurrently. Not only may Bluetooth need to be used for streaming
`
`http://www.radio-electronics.com/info/wireless/bluetooth/bluetooth_edr.php[12/5/2013 11:36:34 AM]
`
`Virginia Innovation Sciences, Ex. 2002.
`
`

`

`Bluetooth 2 | Enhanced Data Rate EDR | Tutorial
`
`audio, but other applications such as running computer peripherals will increase. The reason
` becomes clearer when looking at real situations when interference is present. Typically it is found
` that a good margin is required to allow for re-sends and other data. Under Bluetooth 1.2, high
` quality stereo audio can be sent on its own within the available bandwidth and with sufficient
` margin. However when other applications are added there is not sufficient margin to allow for the
` system to operate satisfactorily. Bluetooth 2 solves this problem and enables sufficient bandwidth
` for a variety of links to be operated simultaneously, while still allowing for sufficient bandwidth
` margin within the system.
`
`There are other advantages to running Bluetooth 2. One of the major elements is in terms of
` power consumption. Although the transmitter and receiver and logic need to be able to handle
` data at a higher speed which normally requires a higher current consumption, this is more than
`outweighed by the fact that they need only to remain fully active for about a third of the time.
` This brings significant advantages in terms of battery life, a feature that is of particular important
` in many of the Bluetooth applications.
`
`Compatibility is a major requirement when any system is upgraded. The same is true for
` Bluetooth, and this has been a major requirement and concern when developing the Bluetooth 2
` standard. The new standard is completely backward compatible and allows networks to contain a
` mixture of EDR (enhanced data rate) devices as well as the standard devices. A key element of
` this is that the new modulation schemes that have been incorporated into Bluetooth 2 are
` compatible in their nature with the standard rate specification. In this way the new standard will
` be able to operate with any mixture of devices from whatever standard.
`
`How it works
`One of the main reasons why Bluetooth 2 is able to support a much higher data throughput is that
` it utilises a different modulation scheme for the payload data. However this is implemented in a
` manner in which compatibility with previous revisions of the Bluetooth standard is still retained.
`
`Bluetooth data is transmitted as packets that are made up from a standard format. This consists
` of four elements which are: (a) The Access Code which is used by the receiving device to
` recognise the incoming transmission; (b) The Header which describes the packet type and its
` length; (c) The Payload which is the data that is required to be carried; and finally (d) The Inter-
`Packet Guard Band which is required between transmissions to ensure that transmissions from
` two sources do not collide, and to enable the receiver to re-tune.
`
`In previous versions of the Bluetooth standard, all three elements of the transmission, i.e. Access
` Code, Header and Payload were transmitted using Gaussian Frequency Shift Keying (GFSK) where
` the carrier is shifted by +/- 160 kHz indicating a one or a zero, and in this way one bit is encoded
` per symbol.
`
`The Bluetooth 2.0 specification uses a variety of forms of modulation. GFSK is still used for
` transmitting the Access Code and Header and in this way compatibility is maintained. However
` other forms of modulation can be used for the Payload. There are two additional forms of
` modulation that have been introduced. One of these is mandatory, while the other is optional.
`
`A further small change is the addition of a small guard band between the Header and the payload.
` In addition to this a short synchronisation word is inserted at the beginning of the payload.
`
`Mandatory modulation format
`The first of the new modulation formats which must be included on any Bluetooth 2 device gives a
` twofold improvement in the data rate and thereby allows a maximum speed of 2 Mbps. This is
` achieved by using pi/4 differential quaternary phase shift keying (pi/4 DQPSK). This form of
`modulation is significantly different to the GFSK that was used on previous Bluetooth standards in
` that the new standard uses a form of phase modulation, whereas the previous ones used on
` frequency modulation.
`
`Using quaternary phase shift modulation means that there are four possible phase positions for
` each symbol. Accordingly this means that two bits can be encoded per symbol, and this provides
` the two fold data increase over the frequency shift keying used for the previous versions of
` Bluetooth.
`
`Higher speed modulation
`To enable the full threefold increase in data rate to be achieved a further form of modulation is
`
`http://www.radio-electronics.com/info/wireless/bluetooth/bluetooth_edr.php[12/5/2013 11:36:34 AM]
`
`Virginia Innovation Sciences, Ex. 2002.
`
`

`

`Bluetooth 2 | Enhanced Data Rate EDR | Tutorial
`
` used. Eight phase differential phase shift keying (8DPSK) enables eight positions to be defined
` with 45 degrees between each of them. By using this form of modulation eight positions are
` possible and three bits can be encoded per symbol. This enables the data rate of 3 Mbps to be
` achieved.
`
`As the separation between the different phase positions is much smaller than it was with the QPSK
` used to provide the two fold increase in speed, the noise immunity has been reduced in favour of
` the increased speed. Accordingly this optional form of modulation is only used when a link is
` sufficiently robust.
`
`Packet formats
`The Bluetooth 2 specification defines ten new packet formats for use with the higher data rate
` modulation schemes, five each for each of the enhanced data rate schemes. Three of these are
` for the 1, 3 and 5 slot asynchronous packets used for transferring data. The remaining two are
`used for 3 and 5 slot extended Synchronous Connection Orientated (eSCO) packets. These use
` bandwidth that is normally reserved for voice communications.
`
`The new format for these packets does not incorporate FEC. If this is required then the system
` switches back automatically to the standard rate packets. However many of the links are over a
` very short range where the signal level is high and the link quality good.
`
`It is necessary for the packet type to be identified so that the receiver can decode them correctly,
` knowing also the type of modulation being used. An identifier is therefore included in the header
` which is sent using GFSK. This packet header used for the previous version of Bluetooth only used
` 4 bits. This gave sufficient capability for the original system. However there was insufficient space
` for the additional information that needed to be sent for Bluetooth 2.
`
`It was not possible to change the header format because backward compatibility would not be
` possible. Instead different link modes are defined. When two Bluetooth 2 or EDR devices
` communicate the messages are used in a slightly different way, indicating the Bluetooth 2 or EDR
`modes. In this way compatibility is retained while still being able to carry the required
` information.
`
`Bluetooth 2 / EDR is a significant improvement to Bluetooth and will enable it to retain its position
` in the market place. Its introduction, as the Bluetooth has become more widely accepted and
` used will enable it to build on its position within the market place.
`
` By Ian Poole
`
`<< Previous | Next >>
`
`Popular wireless tutorials . . . . .
`• Wi-Fi 802.11
`• Bluetooth
`• NFC
`• RFID
`• IEEE 802.22 WRAN
`• DECT
`
`1
`
`4
`
`• 802.15.4
`• WiMAX
`• TransferJet
`
`• SRDs
`• Zigbee
`
`http://www.radio-electronics.com/info/wireless/bluetooth/bluetooth_edr.php[12/5/2013 11:36:34 AM]
`
`Virginia Innovation Sciences, Ex. 2002.
`
`

`

`Bluetooth 2 | Enhanced Data Rate EDR | Tutorial
`
`Radio-Electronics.com is operated and owned by Adrio Communications Ltd and edited by Ian Poole. All information is ©
` Adrio Communications Ltd and may not be copied except for individual personal use. This includes copying material in
` whatever form into website pages. While every effort is made to ensure the accuracy of the information on Radio-
`Electronics.com, no liability is accepted for any consequences of using it. This site uses cookies. By using this site, these
` terms including the use of cookies are accepted. More explanation can be found in our Privacy Policy
`
`http://www.radio-electronics.com/info/wireless/bluetooth/bluetooth_edr.php[12/5/2013 11:36:34 AM]
`
`Virginia Innovation Sciences, Ex. 2002.
`
`