Bluetooth Core Technology Overview (i): Bluetooth overview

 Bluetooth Core Technology Overview (i): Bluetooth overviewTags: bluetooth bluetoothsig2014-07-26 16:01 6143 People read Comments (3) favorite reports Classification:Agreement (+)

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Keywords: Bluetooth core technology Protocol version history
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Bluetooth Core Technology Overview (i): Bluetooth overview
Bluetooth core Technology Overview (ii): Bluetooth usage scenarios
Bluetooth core Technology Overview (III): Bluetooth protocol specification (RF, baseband link control, link management)
Bluetooth core Technology Overview (IV): Bluetooth protocol specification (HCI, L2cap, SDP, RFOCMM)
Bluetooth core Technology Overview (V): Bluetooth protocol specification (IROBEX, BNEP, AVDTP, AVCTP)
First, the origin of the name

Bluetooth This name comes from the tenth century of a Danish king Harald Bluetooth king, Blatand in English meaning can be interpreted as Bluetooth (Bluetooth) because the king likes to eat blueberries, the gums are blue every day so called Bluetooth.
In the preparatory stage of the industry association, a highly expressive name is required to be named for this high-tech. After a night of discussion about European history and the future of wireless technology, some people think it would be appropriate to name the king of Blatand, the industry's organization. King Blatand the Norway, Sweden and Denmark together; his articulate, sociable, like this forthcoming technology, will be defined as allowing for coordination between different industrial sectors, maintaining good communication between the various systems, such as the work of computers, mobile phones and the automotive industry.

Ii. History of development
1994 Ericsson Company Research and Development;
1997 Ericsson contacts other equipment manufacturers;
February 1998, a special interest group SIG (Special Interest Group) from Nokia, Apple and Samsung;
In May 1998, five famous manufacturers, including Ericsson, Nokia, Toshiba, IBM and Intel Corporation, developed jointly;
In the second half of 1999, Microsoft, Motorola, Samsung, Lucent and other mainstream equipment manufacturers widely promote the application of Bluetooth technology;
On October 13, 2006, Bluetooth SIG developed to more than 200 alliance member companies and about 6,000 application member companies.

Third, version information

Bluetooth a total of six version v1.1/1.2/2.0/2.1/3.0/4.0 version information download connection:
1. V1.1 version
Transmission rate is about 748~810kb/s, because it is early design, susceptible to the same frequency of product interference under the influence of communication quality.
2. V1.2 version
The same is only the 748~810kb/s transmission rate, but in addition to (improve software) anti-jamming frequency hopping function.
3. V2.0+edr version
is a 1.2 improved version, the transmission rate of about 1.8m/s~2.1m/s, began to support duplex mode-that is, one side for voice communication, but also can transfer files/high quality pictures, 2.0 version of course also support Stereo operation.
The most widely used is the BLUETOOTH2.0+EDR standard, which was introduced in 2004, and the products that support the Bluetooth 2.0+edr standard also appeared in 2006. Although the Bluetooth 2.0+EDR standard has been extensively improved in technology, it is from 1. The problem of the complexity of the configuration process and the large power consumption of the device continue to exist.
4. V2.1 version
Better power Saving Effect: Bluetooth version 2.1 added the function of sniffsubrating, by setting the signal between the 2 devices to confirm the transmission interval to achieve the purpose of saving power.
5. V3.0+HS version
April 21, 2009, Bluetooth Technology Alliance (bluetooth® SIG) formally promulgated a new generation of standard specification "Bluetooth core Specification version 3.0 High speed" (Bluetooth kernel Specification version 3.0), The core of Bluetooth 3.0 is the "Genericalternate mac/phy" (AMP), a new alternate RF technology that allows the Bluetooth protocol stack to dynamically select the correct RF for any task. The technologies originally expected to be used in the new specification included 802.11 and UMB, but the UMB application was eliminated in the new specification.
6. V4.0 version
Bluetooth 4.0 includes three sub-specifications, namely traditional Bluetooth technology, high-speed Bluetooth and new Bluetooth low-power technology. The improvement of Bluetooth 4.0 is mainly reflected in three aspects, battery life, energy saving and equipment type. With low cost, cross-vendor interoperability, 3 millisecond low latency, over 100 meters of ultra long distance, AES-128 encryption and many other features in addition, the effective transmission distance of Bluetooth 4.0 also improved. The 3.0 version of Bluetooth has a valid transmission distance of 10 meters (about 32 feet), while the effective transmission distance of Bluetooth 4.0 is up to 100 meters (about 328 feet).
Four, the technical characteristics of Bluetooth
To put it simply, Bluetooth is a short-range wideband radio technology that is the global open standard for voice and data wireless transmission. It uses advanced techniques such as frequency hopping spread spectrum (FHSS), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) and so on to establish the information transmission between various communication and information systems in a small scope.
1, the main technical characteristics of Bluetooth:
(1), working band: 2.4GHz Engineering Medical (ISM) band, no need to apply for a license. Most countries use 79 frequency points, with a carrier frequency of (2402+K) MHz (k=0,1, 2 ... 78), carrier frequency interval 1MHz. Use TDD Time Division duplex mode.
(2), transfer rate: 1mb/s (V2.0 or later)
(3), commissioning mode: bt=0.5 GFSK modulation with a modulation index of 0.28-0.35.
(4), using frequency hopping technology:The frequency hopping rate is 1600 hops per second and is increased to 3200 hops per second while the chain is being built, including paging and querying. Bluetooth fast frequency hopping and short packet technology to reduce the interference of the same frequency, to ensure the reliability of transmission.
(5), Voice modulation mode:Continuous variable slope increment modulation (cvsd,continuousvariable Slope delta modulation), strong fading resistance, even if the error rate reaches 4%, the voice quality is acceptable.
(6), support circuit switching and packet switching services:Bluetooth supports real-time synchronous direct join (SCO link) and non-real-time asynchronous non-directional join (ACL link), the former mainly transmits voice and other real-time strong information, the latter with packet-based. Voice and data can be transmitted individually or simultaneously. Bluetooth supports an asynchronous data channel, or three simultaneous simultaneous voice channels, or simultaneous transmission of asynchronous data and synchronized voice channels. Each voice channel supports 64kbps synchronous voice, and the asynchronous channel supports 723.2/57.6kbps asymmetric duplex communication or 433.9kbps symmetric full-duplex communication.
(7), support Point-to-point and point-to-multipoint communication: Bluetooth devices can be composed of two networks in a specific way: Pico (Piconet) and distributed Networks (Scatternet), where the establishment of a Pico network begins with the connection of two devices, which can be composed of up to eight devices. In a pico net, only one master device (Master), the other is from the device (Slave), different master and slave devices can use different links, in one communication, the link can also be arbitrarily changed. Several separate Pico nets are linked together in a specific way to form a distributed network. All Bluetooth devices are equivalent, so there is no concept of a base station in Bluetooth.
(8), Working distance:The Bluetooth device is divided into three power levels: 100mW (20dBm), 2.5mW (4dBm) and 1mW (0dBm), the corresponding effective range is 100 meters, 10 meters and 1 meters.
Five, Bluetooth system composition

1, Radio frequency Unit (RADIO): responsible for the transmission and reception of data and voice, characterized by short distance, low power consumption. The Bluetooth antenna is small in size and light in weight, and belongs to Microstrip antenna.
2, baseband or Link Control Unit (linkcontroller): the RF signal and digital or voice signals to each other to achieve baseband protocol and other underlying connection procedures.
3, Link Management Unit (Linkmanager): responsible for managing the communication between Bluetooth devices, to achieve the establishment of links, verification, link configuration and other operations.
4, Bluetooth Software protocol implementation: such as the purple part, this behind we do detailed instructions.

VI. specification of Bluetooth protocol
Transmission protocol, intermediary Protocol, application protocol;
1. Transmission protocol
Responsible for the Bluetooth devices, mutual confirmation of the location of each other, as well as the establishment and management of the physical link between Bluetooth devices;
Underlying transport protocol:
Bluetooth radio (Radio) section, Baseband Link Management Controller (baseband&link Controller), Link Management Protocol (link Managerprotocol LMP). Responsible for the language, the physical realization of data wireless transmission and the networking network between Bluetooth devices.
High-level transport protocol:
the logical link control is associated with the adapter (Logicallink control and adaptation Protocol) L2cap, the host Control Interface (Hostcontrol INTERFACE,HCI). For high-level applications, the low-frequency sequence selection and other underlying transmission operations are shielded, which provides an effective and useful data grouping format for high-level programs.
2. Intermediary Agreement
Provides the necessary support for high-level application protocols or programs to work on Bluetooth logic links, providing different standard interfaces for applications.
Serial port Emulation protocol: RFCOMM, Service Discovery Protocol: SDP, Interop Protocol IrDA, Network Access Protocol: PPP, IP, TCP, UDP, Telephone Control Protocol: TCS, at instruction set.

3. Application Agreement

Bluetooth protocol stack on top of the application software and the protocols involved, such as: Dial-up Internet, language features of the application.

The Bluetooth application framework is as follows:
(1), General Application Class framework: query, establish connection services, etc.;
(2), Bluetooth Phone application Class framework: Telephone control, language;
(3), Bluetooth Network Application Class framework: Web application related;
(4), Object Interaction Service class framework: IrDA, OBEX;
(5), Bluetooth audio and video control class framework.

Seven, hardware interface
The general Bluetooth chip communicates with the UART, USB, SDIO, I2s, PCCard, and the main control chip. As shown, communicate via UART and master chip.

VIII. Application of Bluetooth
The Bluetooth app is on the phone.
Bluetooth is used on handheld computers.
Bluetooth is used in other digital devices, such as digital cameras, digital video camera, etc.
e-wallets and electronic locks made of the technology of the basket teeth.
The basket system is embedded in the traditional household appliances such as microwave ovens, washing machines, refrigerators and air conditioners.

Bluetooth Core Technology Overview (i): Bluetooth overview