Bluetooth

The word "Bluetooth" is an anglicized version of the Scandinavian Blåtand/Blåtann, (Old Norse blátǫnn) the epithet of the tenth-century king Harald Bluetooth who united dissonant Danish tribes into a single kingdom.                                                                                                                    (Source : Wikipedia)

As you all are familiar with Bluetooth, lets just know about versions.

Bluetooth v1.0 and v1.0B

Versions 1.0 and 1.0B had many problems, and manufacturers had difficulty making their products interoperable. Versions 1.0 and 1.0B also included mandatory Bluetooth hardware device address (BD_ADDR) transmission in the Connecting process (rendering anonymity impossible at the protocol level), which was a major setback for certain services planned for use in Bluetooth environments.

Bluetooth v1.1

• Ratified as IEEE Standard 802.15.1–2002^[39]
• Many errors found in the 1.0B specifications were fixed.
• Added possibility of non-encrypted channels.
• Received Signal Strength Indicator (RSSI).

Bluetooth v1.2

Major enhancements include the following:

• Faster Connection and Discovery
• Adaptive frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence.
• Higher transmission speeds in practice, up to 721 kbit/s,^[40] than in v1.1.
• Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better concurrent data transfer.
• Host Controller Interface (HCI) operation with three-wire UART.
• Ratified as IEEE Standard 802.15.1–2005^[41]
• Introduced Flow Control and Retransmission Modes for L2CAP.

Bluetooth v2.0 + EDR

This version of the Bluetooth Core Specification was released in 2004. The main difference is the introduction of an Enhanced Data Rate (EDR) for faster data transfer. The nominal rate of EDR is about 3 Mbit/s, although the practical data transfer rate is 2.1 Mbit/s.^[40] EDR uses a combination of GFSK and Phase Shift Keying modulation (PSK) with two variants, π/4-DQPSK and 8DPSK.^[42] EDR can provide a lower power consumption through a reduced duty cycle.

The specification is published as Bluetooth v2.0 + EDR, which implies that EDR is an optional feature. Aside from EDR, the 2.0 specification contains other minor improvements, and products may claim compliance to "Bluetooth v2.0" without supporting the higher data rate. At least one commercial device states "Bluetooth v2.0 without EDR" on its data sheet.^[43]

Bluetooth v2.1 + EDR

Bluetooth Core Specification Version 2.1 + EDR was adopted by the Bluetooth SIG on 26 July 2007.^[42]

The headline feature of 2.1 is secure simple pairing (SSP): this improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. See the section on Pairing below for more details.^[44]

2.1 allows various other improvements, including "Extended inquiry response" (EIR), which provides more information during the inquiry procedure to allow better filtering of devices before connection; and sniff subrating, which reduces the power consumption in low-power mode.

Bluetooth v3.0 + HS

Version 3.0 + HS of the Bluetooth Core Specification^[42] was adopted by the Bluetooth SIG on 21 April 2009. Bluetooth 3.0+HS provides theoretical data transfer speeds of up to 24 Mbit/s, though not over the Bluetooth link itself. Instead, the Bluetooth link is used for negotiation and establishment, and the high data rate traffic is carried over a colocated 802.11link.

The main new feature is AMP (Alternative MAC/PHY), the addition of 802.11 as a high speed transport. The High-Speed part of the specification is not mandatory, and hence only devices that display the "+HS" logo actually support Bluetooth over 802.11 high-speed data transfer. A Bluetooth 3.0 device without the "+HS" suffix is only required to support features introduced in Core Specification Version 3.0^[45] or earlier Core Specification Addendum 1.^[46]

Bluetooth v4.0

Bluetooth low energy, previously known as Wibree,^[55] is a subset of Bluetooth v4.0 with an entirely new protocol stack for rapid build-up of simple links. As an alternative to the Bluetooth standard protocols that were introduced in Bluetooth v1.0 to v3.0, it is aimed at very low power applications running off a coin cell. Chip designs allow for two types of implementation, dual-mode, single-mode and enhanced past versions.^[56] The provisional names Wibree and Bluetooth ULP (Ultra Low Power) were abandoned and the BLE name was used for a while. In late 2011, new logos “Bluetooth Smart Ready” for hosts and “Bluetooth Smart” for sensors were introduced as the general-public face of BLE.^[57]

• In a single-mode implementation, only the low energy protocol stack is implemented. STMicroelectronics,AMICCOM, CSR,^[58] Nordic Semiconductor^[59] and Texas Instruments^[60] have released single mode Bluetooth low energy solutions.
• In a dual-mode implementation, Bluetooth Smart functionality is integrated into an existing Classic Bluetooth controller. As of March 2011, the following semiconductor companies have announced the availability of chips meeting the standard: Qualcomm-Atheros, CSR, Broadcom^[61][62] and Texas Instruments. The compliant architecture shares all of Classic Bluetooth’s existing radio and functionality resulting in a negligible cost increase compared to Classic Bluetooth.

Cost-reduced single-mode chips, which enable highly integrated and compact devices, feature a lightweight Link Layer providing ultra-low power idle mode operation, simple device discovery, and reliable point-to-multipoint data transfer with advanced power-save and secure encrypted connections at the lowest possible cost.

General improvements in version 4.0 include the changes necessary to facilitate BLE modes, as well the Generic Attribute Profile (GATT) and Security Manager (SM) services with AES Encryption.

Core Specification Addendum 2 was unveiled in December 2011; it contains improvements to the audio Host Controller Interface and to the High Speed (802.11) Protocol Adaptation Layer.

Core Specification Addendum 3 revision 2 has an adoption date of 24 July 2012.

Core Specification Addendum 4 has an adoption date of 12 February 2013.

Bluetooth v4.1

The Bluetooth SIG announced formal adoption of the Bluetooth 4.1 specification on 4 December 2013. This specification is an incremental software update to Bluetooth Specification v4.0, and not a hardware update. The update incorporates Bluetooth Core Specification Addenda (CSA 1, 2, 3 & 4) and adds new features that improve consumer usability. These include increased co-existence support for LTE, bulk data exchange rates—and aid developer innovation by allowing devices to support multiple roles simultaneously.^[63]

New features of this specification include:

• Mobile Wireless Service Coexistence Signaling
• Train Nudging and Generalized Interlaced Scanning
• Low Duty Cycle Directed Advertising
• L2CAP Connection Oriented and Dedicated Channels with Credit Based Flow Control
• Dual Mode and Topology
• LE Link Layer Topology
• 802.11n PAL
• Audio Architecture Updates for Wide Band Speech
• Fast Data Advertising Interval
• Limited Discovery Time^[64]

Notice that some features were already available in a Core Specification Addendum (CSA) before the release of 4.1.

Bluetooth v4.2

Bluetooth 4.2 was released on December 2, 2014. It Introduces some key features for IOT and is a hardware update.^[65]But some older Bluetooth hardware may receive some Bluetooth 4.2 features, such as privacy updates via firmware.^[66]

The major areas of improvement are:

• LE Data Packet Length Extension
• LE Secure Connections
• Link Layer Privacy
• Link Layer Extended Scanner Filter Policies
• IP connectivity for Bluetooth Smart devices to become available soon after the introduction of BT4.2 via the new Internet Protocol Support Profile (IPSP).
• IPSP adds an IPv6 connection option for Bluetooth Smart, to support connected home and other IoT implementations.
• Bluetooth 4.2 transfers data faster than before by increasing the capacity of the Bluetooth Smart packets.