Bluetooth is a wireless technology standard for exchanging data over short distances (using short- wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Created by telecom vendor Ericsson in 1994,it was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization.
Fig: Logo of Bluetooth
A long time ago (historians differ on the exact dates, but it was sometime in the 10th Century C.E.) in a country far, far away, (which was mostly Denmark, with a little bit of Norway added in for flavor,) there lived a Viking king who was principally noted for converting to a foreign religion called Christianity. He was known as Harald Bluetooth, son of Gorm the Old, and he united most of Denmark before his estranged son, Sven Forkbeard, sent him to Valhalla and took over the family business. A little more than 1000 years later, succumbing to an attack of Scandinavian pride, the giant Swedish telecom manufacturer Ericsson decided to honor old, weird Harald by naming its new wireless networking standard after him. It convinced founding Special Interest Group co-partners Nokia, Toshiba, IBM and Intel that Bluetooth was the right name for the thing and, together, they set off to conquer the air. By December 1, 1999, 3Com, Lucent, Microsoft and Motorola had joined the Promoter Group — the folks that were willing to spend money to hype the standard — and in the neighborhood of 1200 other companies had joined the SIG. (Signing up for membership costs nothing, so it isn’t exactly an exclusive club.) Between them, they manged to generate a lot of coverage about Bluetooth in the trade press.
How does it works:
The technical details of Bluetooth´s function are very complex, and are best studied in detail in the PDF-format documents that can be found on the Bluetooth website. But, superficially speaking, Bluetooth uses frequency hopping in timeslots. Bluetooth has been designed to operate in noisy radio frequency environments, and uses a fast acknowledgement and a frequency-hopping scheme to make the communications 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.
Fig : How does Bluetooth works
Specifications and features
The Bluetooth specification was developed as a cable replacement in 1994 by Jaap Haartsen and Sven Mattisson, who were working for Ericsson in Lund, Sweden. The specification is based on frequency-hopping spread spectrum technology.
The specifications were formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on 20 May 1998. Today it has a membership of over 17,000 companies worldwide. It was established by Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies.
All versions of the Bluetooth standards are designed for downward compatibility. That lets the latest standard cover all older 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.
- Ratified as IEEE Standard 802.15.1–2002
- Many errors found in the 1.0B specifications were fixed.
- Added possibility of non-encrypted channels.
- Received Signal Strength Indicator (RSSI).
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, 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
- 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.EDR uses a combination of GFSK and Phase Shift Keying modulation (PSK) with two variants, π/4-DQPSK and 8DPSK.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, there are other minor improvements to the 2.0 specification, 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.
Bluetooth v2.1 + EDR
Bluetooth Core Specification Version 2.1 + EDR was adopted by the Bluetooth SIG on 26 July 2007.
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.
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 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 collocated 802.11 link.
The main new feature is AMP (Alternate 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 sporting the “+HS” will actually support the Bluetooth over 802.11 high-speed data transfer. A Bluetooth 3.0 device without the “+HS” suffix will not support High Speed, and needs to only support a feature introduced in Core Specification Version 3.0. or earlier Core Specification Addendum 1.
L2CAP Enhanced modes
Enhanced Retransmission Mode (ERTM) implements reliable L2CAP channel, while Streaming Mode (SM) implements unreliable channel with no retransmission or flow control. Introduced in Core Specification Addendum 1.
Enables the use of alternative MAC and PHYs for transporting Bluetooth profile data. The Bluetooth radio is still used for device discovery, initial connection and profile configuration, however when large quantities of data need to be sent, the high speed alternate MAC PHY 802.11 (typically associated with Wi-Fi) will be used to transport the data. This means that the proven low power connection models of Bluetooth are used when the system is idle, and the faster radio is used when large quantities of data need to be sent. AMP links require enhanced L2CAP modes.
Unicast Connectionless Data
Permits service data to be sent without establishing an explicit L2CAP channel. It is intended for use by applications that require low latency between user action and reconnection/transmission of data. This is only appropriate for small amounts of data.
Enhanced Power Control
Updates the power control feature to remove the open loop power control, and also to clarify ambiguities in power control introduced by the new modulation schemes added for EDR. Enhanced power control removes the ambiguities by specifying the behaviour that is expected. The feature also adds closed loop power control, meaning RSSI filtering can start as the response is received. Additionally, a “go straight to maximum power” request has been introduced. This is expected to deal with the headset link loss issue typically observed when a user puts their phone into a pocket on the opposite side to the headset.
The high speed (AMP) feature of Bluetooth v3.0 was originally intended for UWB, but the WiMedia Alliance, the body responsible for the flavor of UWB intended for Bluetooth, announced in March 2009 that it was disbanding, and ultimately UWB was omitted from the Core v3.0 specification.
On 16 March 2009, the WiMedia Alliance announced it was entering into technology transfer agreements for the WiMedia Ultra-wideband (UWB) specifications. WiMedia has transferred all current and future specifications, including work on future high speed and power optimized implementations, to the Bluetooth Special Interest Group (SIG), Wireless USB Promoter Group and the USB Implementers Forum. After the successful completion of the technology transfer, marketing and related administrative items, the WiMedia Alliance will cease operations.
In October 2009 the Bluetooth Special Interest Group suspended development of UWB as part of the alternative MAC/PHY, Bluetooth v3.0 + HS solution. A small, but significant, number of former WiMedia members had not and would not sign up to the necessary agreements for the IP transfer. The Bluetooth SIG is now in the process of evaluating other options for its longer term roadmap.
The Bluetooth SIG completed the Bluetooth Core Specification version 4.0 and has been adopted as of 30 June 2010. It includes Classic Bluetooth, Bluetooth high speed and Bluetooth low energy protocols. Bluetooth high speed is based on Wi-Fi, and Classic Bluetooth consists of legacy Bluetooth protocols.
Bluetooth low energy (BLE), previously known as WiBree, 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. 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.
- In a single mode implementation the low energy protocol stack is implemented solely. CSR, Nordic Semiconductor and Texas Instruments have released single mode Bluetooth low energy solutions.
- In a dual-mode implementation, Bluetooth low energy functionality is integrated into an existing Classic Bluetooth controller. Currently (2011-03) the following semiconductor companies have announced the availability of chips meeting the standard: Qualcomm-Atheros, CSR, Broadcom 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.
Advantage & Disadvantage :
2. Bluetooth is actually inexpensive
3. Bluetooth is automatic
4. Standardized protocol
5. Low interference
6.Sharing voice and data
1. Need more battery power.
2. Using Bluetooth internet sometimes connection may run very slow.
3. Data transfer rate are very slow then the infrared.
4. It is not very secure.
Bluetooth Application :
- · Wireless control of and communication between a mobile phone and a handsfree headset. This was one of the earliest applications to become popular.
- · Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system.
- · Wireless Bluetooth headset and Intercom.
- · Wireless networking between PCs in a confined space and where little bandwidth is required.
- · Wireless communication with PC input and output devices, the most common being the mouse, keyboard and printer.
- · Transfer of files, contact details, calendar appointments, and reminders between devices with OBEX.
- · Replacement of previous wired RS-232 serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices.
- · For controls where infrared was often used.
- · For low bandwidth applications where higher USB bandwidth is not required and cable-free connection desired.
- · Sending small advertisements from Bluetooth-enabled advertising hoardings to other, discoverable, Bluetooth devices.
- · Wireless bridge between two Industrial Ethernet (e.g., PROFINET) networks.
- · Three seventh and eighth generation game consoles, Nintendo‘s Wii. and Sony‘s PlayStation 3, PSP Go and PS Vita, use Bluetooth for their respective wireless controllers.
- · Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem.
- · Short range transmission of health sensor data from medical devices to mobile phone, set-top box or dedicated telehealth devices.
- · Allowing a DECT phone to ring and answer calls on behalf of a nearby mobile phone.
- · Real-time location systems (RTLS), are used to track and identify the location of objects in real-time using “Nodes” or “tags” attached to, or embedded in the objects tracked, and “Readers” that receive and process the wireless signals from these tags to determine their locations.
· Personal security application on mobile phones for prevention of theft or loss of items. The protected item has a Bluetooth marker (e.g. a tag) that is in constant communication with the phone. If the connection is broken (the marker is out of range of the phone) then an alarm is raised. This can also be used as a man overboard alarm. A product using this technology has been available since 2009.
Fig: Some Bluetooth applications
Uses of Bluetooth :
3.Medical and health devices
Future of Bluetooth:
Many of us think that Bluetooth is going to be here stay but it is wrong. Bluetooth is able to complete all other technologies such as Wi-Fi networking infrared data association etc.Consumers are more interested in application then the technologies. It is must benefits for consumers. Bluetooth has a good future ahead because it meets a basic need of connectivity in close proximity, is the result of initiatives of nine leading communications and computer industry vendors including companies like 3-COM, Ericsson, Lucent, IBM, Intel, Microsoft, Nokia, Toshiba etc. Since the formation of the original group, more than 1800 manufacturers worldwide have joined the initiative worldwide. According to one market research report, Bluetooth technology is expected to be built into over 100 millions devices before the end of 2002. According to still another report from market research firm Cahners In-Stat Group, there will be over 670 million Bluetooth enabled devices worldwide by 2005.
As a result of success of WAP (Wireless Application Protocol), adoption of smart phones and handheld devices, Bluetooth will have tremendous effects on everyday life. Bluetooth is one of the key technologies that can make the mobile information society possible, blurring the boundaries between home , the office, and the outside world. The seamless connectivity promised by Bluetooth makes it possible to explore a range of interactive and highly transparent personalized services. Already many Bluetooth pilot products have rolled into the market backed by big vendors, which is a very healthy sign for the acceptance of the technology. The support for Bluetooth is not limited to companies developing Bluetooth enabled products only. Bluetooth applications can have far reaching impacts on many other industries as well. Bluetooth technology adoption is expected to be widespread throughout the computer and telecommunications industry. Implementation of the Bluetooth technology is expected to grow the market for personal mobile devices and indirectly increase airtime usage for wireless data. Over the long term. manufacturers will also benefit from the ability to replace multiple connection ports with a single Bluetooth module, gaining economies at the production level. The Bluetooth SIG has defined favorable adoption terms, including open, royalty-free availability of the specification and is playing an important role in spreading the technology.
- Looking Forward Version
Version 1.2 ready to release
- Adaptive frequency hopping for better noice immunity
- Better security and audio processing features
- Still on the anvil
- Proposed to support medium (2-3 Mbps) and high bit rates (12 Mbps)
Bluetooth protocol stack
Bluetooth Protocol Stack
Bluetooth is defined as a layer protocol architecture consisting of core protocols, cable replacement protocols, telephony control protocols, and adopted protocols. Mandatory protocols for all Bluetooth stacks are: LMP, L2CAP and SDP. In addition, devices that communicate with Bluetooth almost universally can use these protocols: HCI and RFCOMM.
The Link Management Protocol (LMP) is used for set-up and control of the radio link between two devices. Implemented on the controller.
A/V Remote Control Profile. Commonly used in car navigation systems to control streaming Bluetooth audio. Adopted versions 1.0, 1.3 & 1.4
The Logical Link Control and Adaptation Protocol (L2CAP) Used to multiplex multiple logical connections between two devices using different higher level protocols. Provides segmentation and reassembly of on-air packets.
In Basic mode, L2CAP provides packets with a payload configurable up to 64 kB, with 672 bytes as the default MTU, and 48 bytes as the minimum mandatory supported MTU.
In Retransmission and Flow Control modes, L2CAP can be configured either for isochronous data or reliable data per channel by performing retransmissions and CRC checks.
Bluetooth Core Specification Addendum 1 adds two additional L2CAP modes to the core specification. These modes effectively deprecate original Retransmission and Flow Control modes:
- Enhanced Retransmission Mode (ERTM): This mode is an improved version of the original retransmission mode. This mode provides a reliable L2CAP channel.
- Streaming Mode (SM): This is a very simple mode, with no retransmission or flow control. This mode provides an unreliable L2CAP channel.
Reliability in any of these modes is optionally and/or additionally guaranteed by the lower layer Bluetooth BDR/EDR air interface by configuring the number of retransmissions and flush timeout (time after which the radio will flush packets). In-order sequencing is guaranteed by the lower layer.
Only L2CAP channels configured in ERTM or SM may be operated over AMP logical links.
The Service Discovery Protocol (SDP) allows a device to discover services offered by other devices, and their associated parameters. For example, when you use a mobile phone with a Bluetooth headset, the phone uses SDP to determine which Bluetooth profiles the headset can use (Headset Profile, Hands Free Profile, Advanced Audio Distribution Profile (A2DP) etc.) and the protocol multiplexer settings needed for the phone to connect to the headset using each of them. Each service is identified by a Universally Unique Identifier (UUID), with official services (Bluetooth profiles) assigned a short form UUID (16 bits rather than the full 128).
Radio Frequency Communications (RFCOMM) is a cable replacement protocol used to create a virtual serial data stream. RFCOMM provides for binary data transport and emulates EIA-232 (formerly RS-232) control signals over the Bluetooth baseband layer, i.e. it is a serial port emulation.
RFCOMM provides a simple reliable data stream to the user, similar to TCP. It is used directly by many telephony related profiles as a carrier for AT commands, as well as being a transport layer for OBEX over Bluetooth.
Many Bluetooth applications use RFCOMM because of its widespread support and publicly available API on most operating systems. Additionally, applications that used a serial port to communicate can be quickly ported to use RFCOMM.
The Bluetooth Network Encapsulation Protocol (BNEP) is used for transferring another protocol stack’s data via an L2CAP channel. Its main purpose is the transmission of IP packets in the Personal Area Networking Profile. BNEP performs a similar function to SNAP in Wireless LAN.
The Audio/Video Control Transport Protocol (AVCTP) is used by the remote control profile to transfer AV/C commands over an L2CAP channel. The music control buttons on a stereo headset use this protocol to control the music player.
The Audio/Video Distribution Transport Protocol (AVDTP) is used by the advanced audio distribution profile to stream music to stereo headsets over an L2CAP channel. Intended to be used by video distribution profile in the bluetooth transmission.
The Telephony Control Protocol – Binary (TCS BIN) is the bit-oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices. Additionally, “TCS BIN defines mobility management procedures for handling groups of Bluetooth TCS devices.”
TCS-BIN is only used by the cordless telephony profile, which failed to attract implementers. As such it is only of historical interest.
Adopted protocols are defined by other standards-making organizations and incorporated into Bluetooth’s protocol stack, allowing Bluetooth to create protocols only when necessary. The adopted protocols include:
Point-to-Point Protocol (PPP)
Internet standard protocol for transporting IP datagrams over a point-to-point link.
Foundation Protocols for TCP/IP protocol suite
Object Exchange Protocol (OBEX)
Session-layer protocol for the exchange of objects, providing a model for object and operation representation
Wireless Application Environment/Wireless Application Protocol (WAE/WAP)
WAE specifies an application framework for wireless devices and WAP is an open standard to provide mobile users access to telephony and information services.
Baseband error correction
Depending on packet type, individual packets may be protected by error correction, either 1/3 rate forward error correction (FEC) or 2/3 rate. In addition, packets with CRC will be retransmitted until acknowledged by automatic repeat request (ARQ
- When not using Bluetooth turn off.
- Set your Bluetooth mode so that it is not discoverable.
- Be careful of devices that may have a guessable pass code.
- Be careful when setting a device to “trusted “or ”authorized” as that device can then access of your devices services, features and potentially-data.
Bluetooth is a short range wireless technology that will make connections between various devices. Bluetooth technology takes away the need for several problematic cable attachments for connecting mobile phones ,handheld devices and computers. It is easy simple and inexpensive. Whenever think of wireless think Bluetooth this is the best way of communication.