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Bluetooth Tutorial - Specifications
Posted Date: 21 Feb 2008 Resource Type: Articles/Knowledge Sharing Category: General
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Posted By: satish Member Level: Gold
Rating:  Points: 5
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Bluetooth Tutorial - Specifications
What is Bluetooth? Well you can get lots of different definitions, but essentially Bluetooth is the term used to describe the protocol of a short range (10 meter) frequency-hopping radio link between devices. These devices are then termed Bluetooth - enabled. Documentation on Bluetooth is split into two sections, the Bluetooth Specification and Bluetooth Profiles.
• The Specification describes how the technology works (i.e the Bluetooth protocol architecture),
• The Profiles describe how the technology is used (i.e how different parts of the specification can be used to fulfil a desired function for a Bluetooth device)
The Specification is examined first, then the Profiles.
Bluetooth Specification Protocol Stack:
Click on a section of the diagram* above, for a tutorial of its functions
In more detail: Bluetooth is the name given to a new technology using short-range radio links, intended to replace the cable(s) connecting portable and/or fixed electronic devices. It is envisaged that it will allow for the replacement of the many propriety cables that connect one device to another with one universal radio link. Its key features are robustness, low complexity, low power and low cost. Designed to operate in noisy frequency environments, the Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust. Bluetooth radio modules operate in the unlicensed ISM band at 2.4GHz, and avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet. Compared with other systems in the same frequency band, the Bluetooth radio hops faster and uses shorter packets. The following pages give more detail about different sections of the protocol, note this tutorial is completely up to date with the latest version of the bluetooth Specification (ver 1.1)
Specification Table Of Contents:
1 Radio
v1.1
The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2.4 GHz ISM band.
2 Baseband
v1.1
The Baseband layer describes the specification of the Bluetooth Link Controller (LC) which carries out the baseband protocols and other low-level link routines.
3 LMP
v1.1
The Link Manager Protocol (LMP) is used by the Link Managers (on either side) for link set-up and control.
4 HCI
v1.1
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.
5 L2CAP
v1.1
Logical Link Control and Adaptation Protocol (L2CAP) supports higher level protocol multiplexing, packet segmentation and reassembly, and the conveying of quality of service information.
6 RFCOMM
v1.1
The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol. The protocol is based on the ETSI standard TS 07.10.
7 SDP
v1.1
The Service Discovery Protocol (SDP) provides a means for applications to discover which services are provided by or available through a Bluetooth device. It also allows applications to determine the characteristics of those available services.
Compare with Other Technologies
The wireless world continues to grow as engineers develop faster, more robust technologies to free us from wires for greater simplicity, convenience, and efficiency. From short range to long range, the wireless landscape has taken shape in our lives. Bluetooth wireless technology, though one among many, has a wide variety of applications. A comparison of Bluetooth technology with other technologies is helpful when deciding which technologies to implement or products to purchase.
Bluetooth Wireless Technology
• Bluetooth wireless technology is geared towards voice and data applications
• Bluetooth wireless technology operates in the unlicensed 2.4 GHz spectrum
• Bluetooth wireless technology can operate over a distance of 10 meters or 100 meters depending on the Bluetooth device class. The peak data rate with EDR is 3 Mbps
• Bluetooth wireless technology is able to penetrate solid objects
• Bluetooth technology is omni-directional and does not require line-of-sight positioning of connected devices
• Security has always been and continues to be a priority in the development of the Bluetooth specification. The Bluetooth specification allows for three modes of security
• The cost of Bluetooth chips is under $3
Ultra-Wideband (UWB)
• UWB is a revolutionary wireless technology for transmitting digital data over a wide spectrum of frequency bands with very low power. It can transmit data at very high rates (for wireless local area network applications)
• To date, UWB only has regulatory approval in the United States. UWB products are slow to come to market due to the disagreements over the standard and the lack of global regulatory approval
• Ideally, it will have low power consumption, low price, high speed, use a wide swath of radio spectrum, carry signals through obstacles (doors, etc.) and apply to a wide range of applications (defense, industry, home, etc.)
• Currently, there are two competing UWB standards. The UWB Forum is promoting one standard based on direct sequence (DS-UWB). The WiMedia Alliance is promoting another standard based on Multi-band Orthogonal Frequency Division Modulation (OFDM)
• Each standard allows for data rates from approximately 0-500 Mbps at a range of 2 meters and a data rate of approximately 110 Mbps at a range of up to 10 meters
• The Bluetooth SIG announced in May 2005 its intentions to work with both groups behind UWB to develop a high rate Bluetooth specification on the UWB radio
Certified Wireless USB
• Speed: Wireless USB is projected to be 480 Mbps up to 2 meters and 110 Mbps for up to 10 meters. Wireless USB hub can host up to 127 wireless USB devices
• Wireless USB will be based on and run over the UWB radio promoted by the WiMedia Alliance.
• Allows point-to-point connectivity between devices and the Wireless USB hub
• Intel established the Wireless USB Promoter Group in February 2004
• The USB Implementers Forum, Inc. (USB-IF) tests and certifies the "certified Wireless USB" based wireless equipment
Wi-Fi (IEEE 802.11)
• Bluetooth technology costs a third of Wi-Fi to implement
• Bluetooth technology uses a fifth of the power of Wi-Fi
• The Wi-Fi Alliance tests and certifies 802.11 based wireless equipment
• 802.11a: This uses OFDM, operates in the 5 GHz range, and has a maximum data rate of 54 Mbps
• 802.11b: Operates in the 2.4 GHz range, has a maximum data rate of 11 Mbps and uses DSSS. 802.11b is the original Wi-Fi standard
• 802.11g: Operates in the 2.4 GHz range, uses OFDM and has a maximum data rate of 54 Mbps. This is backwards compatible with 802.11b
• 802.11e: This standard will improve quality of service
• 802.11h: This standard is a supplement to 802.11a in Europe and will provide spectrum and power control management. Under this standard, dynamic frequency selection (FS) and transmit power control (TPC) are added to the 802.11a specification
• 802.11i: This standard is for enhanced security. It includes the advanced encryption standard (AES). This standard is not completely backwards compatible and some users will have to upgrade their hardware. The full 802.11i support is also referred to as WPA2
• 802.11k: Under development, this amendment to the standard should allow for increased radio resource management on 802.11 networks
• 802.11n: This standard is expected to operate in the 5 GHz range and offer a maximum data rate of over 100 Mbps (though some proposals are seeking upwards of 500 Mbps). 802.11n will handle wireless multimedia applications better than the other 802.11 standards
• 802.11p: This standard will operate in the automotive-allocated 5.9 GHz spectrum. It will be the basis for the dedicated short range communications (DSRC) in North America. The DSRC will allow vehicle to vehicle and vehicle to roadside infrastructure communication
• 802.11r: This amendment to the standard will improve users’ ability to roam between access points or base stations. The task group developing this form in spring/summer 2004
• 802.11s: Under development, this amendment to the standard will allow for mesh networking on 802.11 networks. The task group developing this formed in spring/summer 2004
WiMAX (Worldwide Interoperability for Microwave Access and IEEE 802.16)
• WiMax is a wireless metropolitan area network (MAN) technology
• WiMax has a range of 50 km with data rates of 70 Mbps. Typical cell has a shorter range
• The original 802.16 standard operated in the 10-66 GHz frequency bands with line of sight environments
• The newly completed 802.16a standard operates between 2 and 11 GHz and does not need line of sight
• Delays in regulatory approval in Europe due to issues regarding the use of the spectrums in the 2.8 GHz and 3.4 GHz range
• Supports vehicle mobility for between 20 to 100+ km/hr. The 802.16e standard will allow nomadic portability
• The IEEE 802.16a and the ETSI HIPERMAN (High Performance Radio Metropolitan Area Network) share the same PHY and MAC. 802.16 has been designed from the beginning to be compatible with the European standard
• Created to compete with DSL and cable modem access, the technology is considered ideal for rural, hard to wire areas
WiBro (Wireless Broadband)
• Portable Internet Service (WiBro) is to provide a high data rate wireless internet access with PSS (Personal Subscriber Station) under the stationary or mobile environment, anytime and anywhere. Primarily based in South Korea based on TTA specifications.
• 2300-2400 MHz, TDD, OFDMA, channel bandwidth 10 MHz, etc.
• System shall support mobile users at a velocity of up to 60km/h
• Throughput (per user) Max. DL / UL = 3 / 1 [Mbps], Min. DL / UL = 512 / 128 [Kbps]
• Will come online Q1 2006
Infrared (IrDA)
• IrDA is used to provide wireless connectivity for devices that would normally use cables to connect. IrDA is a point-to-point, narrow angle (30° cone), ad-hoc data transmission standard designed to operate over a distance of 0 to 1 meter and at speeds of 9600 bps to 16 Mbps
• IrDA is not able to penetrate solid objects and has limited data exchange applications compared to other wireless technologies
• IrDA is mainly used in payment systems, in remote control scenarios or when synchronizing two PDAs with each other
Radio Frequency Identification (RFID)
• There are over 140 different ISO standards for RFID for a broad range of applications
• With RFID, a passive or unpowered tag can be powered at a distance by a reader device. The receiver, which must be within a few feet, pulls information off the ‘tag,’ and then looks up more information from a database. Alternatively, some tags are self-powered, ‘active’ tags that can be read from a greater distance
• RFID can operate in low frequency (less than 100 MHz), high frequency (more than 100 MHz), and UHF (868 to 954 MHz)
• Uses include tracking inventory both in shipment and on retail shelves
Near Field Communication (NFC)
• The NFC Forum is involved in the development and promotion of NFC. The 12 sponsor members of the NFC Forum include MasterCard International, Microsoft, Motorola, NEC, Nokia, Panasonic, Philips, Renesas, Samsung Electronics, Sony, Texas Instruments and Visa
• Capacity: 212 kbps over a distance from 0 to 20 centimeters over the 13.56 Mhz frequency range
• The NFC standard is based on RFID technology
• Applications suggested for NFC include ticketing, payment and gaming.
• Support for a passive mode of communication leads to savings on battery power
Near-Field Magnetic Communication
• Proprietary wireless technology developed, patented and licensed by Aura Communications.
• Range: 1.5 to 2 meters; Power: about 100 nanowatts; and frequency: 10 to 15 MHz. Creates a weak magnetic bubble of 4 to 6 feet in diameter in which it works
• Currently this technology is only used for wireless headsets. An adapter must be attached to the phone since it is not integrated in any handset
• Only available in the U.S. to-date
HiperLAN
• Speed: HiperLAN 2 = 54 Mbps, and has a 50 to 100 m capacity
• No present killer application
HIPERMAN
• Fixed wireless access standard developed by the European Telecommunications Standards Institute (ETSI)
• Operates in the spectrum between 2 GHz and 11 GHz and is compatible/interoperable with the IEEE 802.16a-2003 standard
802.20
• Considered to be mobile wireless broadband wireless access.
• Maximum data rate expected to be 1 Mbps, operating in licensed bands below 3.5 GHz
• Supports vehicle mobility up to 250 km/hr
ZigBee (IEEE 802.15.4)
The nine promoter companies of the ZigBee Alliance include Philips, Honeywell, Mitsubishi Electric, Motorola, Samsung, BM Group, Chipcon, Freescale and Ember; more than 70 members
• Capacity of 250 Kbits at 2.4 GHz, 40 Kpbs at 915 Mhz, and 20 Kpbs at 868 Mhz with a range of 10-100 M
• Its purpose is to become a wireless standard for remote control in the industrial field
• The ZigBee technology is targeting the control applications industry, which does not require high data rates, but must have low power, low cost and ease of use (remote controls, home automation, etc.)
• The specification was formally adopted in December 2004
• Security was not considered in the initial development of the specification. Currently there are three levels of security
• ZigBee and Bluetooth chips are both low cost.
Security
Other Resources
• Bluetooth v2.1+EDR with improved security features.
• Security Q and A.
• Protecting your device.
• More device pairing help.
Tips to protect your data
Non-Discoverable Mode
Turn the device to non-discoverable mode when not using Bluetooth wireless technology and in unknown areas.
Only Pair with Known Devices
Don't "pair" with unknown devices. If a user were to receive an invitation to pair with another device, and asked to put in a PIN code, but was unsure of what device was inviting to pair, the user should not pair.
Today's wireless world means that data is being sent, among us, invisibly from device to device, country to country, person to person. This data, in the form of e-mails, photos, contacts and addresses, is precious and private to each of us. This private information, no longer making its way along wires in plain sight, needs to be sent securely to its intended recipient without interception. Wireless standards the world over are evolving and have various formats for dealing with the security issues of its users. Bluetooth wireless technology is no exception.
Bluetooth wireless technology has, from its inception, put great emphasis on wireless security so that users of this global standard can feel secure while making their connections. The Bluetooth Special Interest Group (SIG), made up of over 8,000 member manufacturers, has a Bluetooth security experts group made up of engineers from its member companies who provide critical security information and feedback that is taken into account as the Bluetooth wireless specification evolves.
Implementing Security
Product developers that use Bluetooth wireless technology in their products have several options for implementing security. There are three modes of security for Bluetooth access between two devices.
Security Mode 1: non-secure
Security Mode 2: service level enforced security
Security Mode 3: link level enforced security
The manufacturer of each product determines these security modes. Devices and services also have different security levels. For devices, there are two levels: "trusted device" and "untrusted device." A trusted device, having been paired with one's other device, has unrestricted access to all services.With regard to services, three security levels are defined: services that require authorization and authentication, services that require authentication only and services that are open to all devices.
Misinformation Surrounding Security
Lately, confusion and misinformation surrounding security and Bluetooth wireless technology has increased. The current security issues typically involve mobile phones. How these issues apply to other classes of devices is important and is often not addressed. The encryption algorithm in the Bluetooth specifications is secure. This includes devices such as mice and keyboards connecting to a PC, a mobile phone synchronizing with a PC, and a PDA using a mobile phone as a modem to name just a few of the many use cases.
Cases where data has been compromised on mobile phones are the result of implementation issues on that platform. The Bluetooth SIG diligently works with our members to investigate any issues that are reported to understand the root cause of the issue. If it is a specification issue, we work with the membership to get patches out and ensure future devices don't suffer from the same vulnerability. This is an on-going process. The recently reported issues of advanced "hackers" gaining access to information stored on select mobile phones using Bluetooth functionality are due to incorrect implementation. The names bluesnarfing and bluebugging have been given to these methods of illegal and improper access to information. The questions and answers below provide users with more information about these current issues and will address their concerns for dealing with these security risks.
How Bluetooth Technology Works
Bluetooth wireless technology is a short-range communications system intended to replace the cables connecting portable and/or fixed electronic devices. The key features of Bluetooth wireless technology are robustness, low power, and low cost. Many features of the core specification are optional, allowing product differentiation.
The Bluetooth core system consists of an RF transceiver, baseband, and protocol stack. The system offers services that enable the connection of devices and the exchange of a variety of data classes between these devices.
Overview of Operation
The Bluetooth RF (physical layer) operates in the unlicensed ISM band at 2.4GHz. The system employs a frequency hop transceiver to combat interference and fading, and provides many FHSS carriers. RF operation uses a shaped, binary frequency modulation to minimize transceiver complexity. The symbol
rate is 1 Megasymbol per second (Msps) supporting the bit rate of 1 Megabit per second (Mbps) or, with Enhanced Data Rate, a gross air bit rate of 2 or 3Mb/s. These modes are known as Basic Rate and Enhanced Data Rate respectively.
During typical operation, a physical radio channel is shared by a group of devices that are synchronized to a common clock and frequency hopping pattern. One device provides the synchronization reference and is known as the master. All other devices are known as slaves. A group of devices synchronized in this fashion form a piconet. This is the fundamental form of communication for Bluetooth wireless technology.
Devices in a piconet use a specific frequency hopping pattern which is algorithmically determined by certain fields in the Bluetooth specification address and clock of the master. The basic hopping pattern is a pseudo-random ordering of the 79 frequencies in the ISM band. The hopping pattern may be adapted to exclude a portion of the frequencies that are used by interfering devices. The adaptive hopping technique improves Bluetooth technology co-existence with static (non-hopping) ISM systems when these are co-located.
The physical channel is sub-divided into time units known as slots. Data is transmitted between Bluetooth enabled devices in packets that are positioned in these slots. When circumstances permit, a number of consecutive slots may be allocated to a single packet. Frequency hopping takes place between the transmission or reception of packets. Bluetooth technology provides the effect of full duplex transmission through the use of a time-division duplex (TDD) scheme.
Above the physical channel there is a layering of links and channels and associated control protocols. The hierarchy of channels and links from the physical channel upwards is physical channel, physical link, logical transport, logical link and L2CAP channel.
Within a physical channel, a physical link is formed between any two devices that transmit packets in either direction between them. In a piconet physical channel there are restrictions on which devices may form a physical link. There is a physical link between each slave and the master. Physical links are not formed directly between the slaves in a piconet.
The physical link is used as a transport for one or more logical links that support unicast synchronous, asynchronous and isochronous traffic, and broadcast traffic. Traffic on logical links is multiplexed onto the physical link by occupying slots assigned by a scheduling function in the resource manager.
A control protocol for the baseband and physical layers is carried over logical links in addition to user data. This is the link manager protocol (LMP). Devices that are active in a piconet have a default asynchronous connection-oriented logical transport that is used to transport the LMP protocol signaling. For historical reasons this is known as the ACL logical transport. The default ACL logical transport is the one that is created whenever a device joins a piconet. Additional logical transports may be created to transport synchronous data streams when this is required.
The link manager function uses LMP to control the operation of devices in the piconet and provide services to manage the lower architectural layers (radio layer and baseband layer). The LMP protocol is only carried on the default ACL logical transport and the default broadcast logical transport.
Above the baseband layer the L2CAP layer provides a channel-based abstraction to applications and services. It carries out segmentation and reassembly of application data and multiplexing and de-multiplexing of multiple channels over a shared logical link. L2CAP has a protocol control channel that is carried over the default ACL logical transport. Application data submitted to the L2CAP protocol may be carried on any logical link that supports the L2CAP protocol.
Bluetooth Basics
Bluetooth wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The key features of Bluetooth technology are robustness, low power, and low cost. The Bluetooth specification defines a uniform structure for a wide range of devices to connect and communicate with each other.
Bluetooth technology has achieved global acceptance such that any Bluetooth enabled device, almost everywhere in the world, can connect to other Bluetooth enabled devices in proximity. Bluetooth enabled electronic devices connect and communicate wirelessly through short-range, ad hoc networks known as piconets. Each device can simultaneously communicate with up to seven other devices within a single piconet. Each device can also belong to several piconets simultaneously. Piconets are established dynamically and automatically as Bluetooth enabled devices enter and leave radio proximity.
A fundamental Bluetooth wireless technology strength is the ability to simultaneously handle both data and voice transmissions. This enables users to enjoy variety of innovative solutions such as a hands-free headset for voice calls, printing and fax capabilities, and synchronizing PDA, laptop, and mobile phone applications to name a few.
Core Specification Versions
• Version 2.0 + Enhanced Data Rate (EDR), adopted November, 2004
• Version 1.2, adopted November, 2003
Specification Make-Up
Unlike many other wireless standards, the Bluetooth wireless specification gives product developers both link layer and application layer definitions, which supports data and voice applications.
Spectrum
Bluetooth technology operates in the unlicensed industrial, scientific and medical (ISM) band at 2.4 to 2.485 GHz, using a spread spectrum, frequency hopping, full-duplex signal at a nominal rate of 1600 hops/sec. The 2.4 GHz ISM band is available and unlicensed in most countries.
Interference
Bluetooth technology’s adaptive frequency hopping (AFH) capability was designed to reduce interference between wireless technologies sharing the 2.4 GHz spectrum. AFH works within the spectrum to take advantage of the available frequency. This is done by detecting other devices in the spectrum and avoiding the frequencies they are using. This adaptive hopping allows for more efficient transmission within the spectrum, providing users with greater performance even if using other technologies along with Bluetooth technology. The signal hops among 79 frequencies at 1 MHz intervals to give a high degree of interference immunity.
MORE INFORMATION
• Benefits
• How Bluetooth Technology Works
• Core Specification v2.1 + EDR
• Specification Documents
• Compare Technologies
• Wireless Security
Range
The operating range depends on the device class:
• Class 3 radios – have a range of up to 1 meter or 3 feet
• Class 2 radios – most commonly found in mobile devices – have a range of 10 meters or 30 feet
• Class 1 radios – used primarily in industrial use cases – have a range of 100 meters or 300 feet
Power
The most commonly used radio is Class 2 and uses 2.5 mW of power. Bluetooth technology is designed to have very low power consumption. This is reinforced in the specification by allowing radios to be powered down when inactive.
Data Rate
1 Mbps for Version 1.2; Up to 3 Mbps supported for Version 2.0 + EDR
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