1、BluetoothIntroductionBluetooth is a forever, limited radio connect that resides on a microchip. It was originally expanded through Swedish mobile phone creator Ericsson in 1994 as a method to let laptop computers make calls above a mobile phone. As then, numerous organizations have signed on to crea
2、te Bluetooth the low-power thoughtless wireless average for a broad variety of devices (LeVitus, 216-220). Industry spectators anticipate Bluetooth to be fitted in billions of devices through 2005.DiscussionDeveloped by engineers at Ericsson in the late 1990s, Bluetooth is more and more special tech
3、nology that facilitates thoughtless wireless communication among a diversity of electronic devices. Its mainly important aspect is that it permits devices to “talk” (relocate and orchestrate data) wirelessly with each other, terminating the requirement for the outwardly continuous tangle of cables,
4、cords, and adapters important for numerous todays expertise.The Bluetooth Special Interest Group (SIG) was formed in 1998 to manage the expansion and prologue of Bluetooth knowledge (LeVitus, 216-220). IBM, Intel, Toshiba and Nokia connected with Ericsson as the beginning associates of the SIG, and
5、in excess of 8,000 organizations have contracted since. So as to trade products with the Bluetooth requirement and logo, manufacturers should be associates of the SIG and the devices should meet well-outlined credentials. These procedures make sure that Bluetooth wireless devices international may c
6、onverse with each other, apart from company or nation of derivation.Speed and RangeRange is application specific and although a minimum range is mandated by the Core Specification, there is not a limit and manufacturers can tune their implementation to support the use case they are enabling. Range m
7、ay vary depending onclass of radio used in an implementation: 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 33 feet Class 1 radios used primarily in industrial use cases , have a range of 100 meters or 300 f
8、eetThat creates Bluetooth technology appropriate for transporting lesser files for example cell phone contracts and text documents, also as lower-quality pictures and audio (Kumkum, 160-162). At these relocate speeds; Bluetooth may not actually deal streaming video or high-quality pictures and audio
9、 at this end, except this possibly will alter in the future when fresh Bluetooth standards are initiated.Simple and Competent to UtilizeCreating and configuring Bluetooth allowed devices is moderately uncomplicated, with little extra commotion than acquire the two devices close to one another and tw
10、ist them on. There is no requirement to mount drivers or further software to complex an ad-hoc, personal wireless network (Kumkum, 160-162). It has a uniform organization, meaning that some two wireless products attributing Bluetooth technology, despite of product or nation of origin, have the abili
11、ty to converse faultlessly with each other.Common ApplicationsOne of the mainly ordinary applications of Bluetooth is hands-free cell phone procedure. About each cell phone fashioned in our day has constructed Bluetooth (Meier, 15-20). Only pair phone with a Bluetooth headset, and he may talk wherea
12、s his phone is in his purse or pocket. Several of todays car stereos as well have fitted Bluetooth for hands-free calling in his vehicle. And if his vehicle has a plant stereo or grown-up aftermarket one that he merely doesnt wish to restore, he may yet like hands-free identifying with a Bluetooth c
13、ar kit.Bluetooth 3.0Bluetooth 3.0 is the fresh Bluetooth wireless typical adopted through the Bluetooth SIG on April 21, 2009. The fresh standard supports elevated data remove speeds and constructs ahead the preceding standards (Meier, 15-20). With its superior speed, the technology has the probable
14、 to transfigure the consumer electronics industry.TechnologyPROTOCOLThe Bluetooth technology standard is set to make different applications can “communicate” with each other. Remote devices in communication use the same protocol stacks, while different applications need different protocol stacks. Bu
15、t, every application needs the data link layer and physical layer of the Bluetooth technology. The whole Bluetooth protocol stacks is shown as blow. Not any application should use all of the protocols, but one or some lists of these. The chart below shows the relationship between protocols, but the
16、relationship may change in some applications.The completely protocol stacks include Bluetooth special protocols (like LMP and L2CAP) and not special ones (such as OBEX and UDP). The basic principle for designing protocol and protocol stacks is that use existing high level protocol as possible, ensur
17、e the combination of protocols and Bluetooth technology, and take the best advantage of the software and hardware which adapt to the Bluetooth technology standards. The open Bluetooth technology makes device manufacturers can choose protocols freely as they like or used to.The protocols in Bluetooth
18、 protocol systemThere are four layers in Bluetooth protocol system according to the SIG Core protocols Cable replacement protocols Telephony control protocols Adopted protocolsExcept the protocol layers above, the standard also defines Host/Controller Interface (HCI),which provides command interface
19、 for baseband controller, connection manager, hardware state and control register.Bluetooth core protocols consist of the special protocols made by SIG. Most Bluetooth devices need core protocols, while other protocols are used depend on needs of the application. After all, cable replacement protoco
20、ls, technology control protocols and adopted protocols based on the core protocols constitute the object-oriented protocols. Core protocols LMP (Link Management Protocol)Used for control of the radio link between two devices. Implemented on the controllers.It identifies and encrypts through launchin
21、g, exchanging and checking the connection, and decides the size of baseband data packets through conference. It also controls the power mode and work cycle of wireless equipment, and connection status of unit equipment in piconet. L2CAP (Logical Link Control & Adaptation Protocol)This protocol is us
22、ed to multiplex multiple logical connections between two devices using different higher level protocols, and provides segmentation and reassembly of on-air packets.In Basic mode, L2CAP provides packets with a payload configurable up to 64kB, with 672 bytes as the default MTU, and 48 bytes as the min
23、imum mandatory supported MTU.In Retransmission & Flow Control modes, L2CAP can be configured for reliable or isochronous 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 effect
24、ively 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 cont
25、rol. 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-ord
26、er sequencing is guaranteed by the lower layer.Only L2CAP channels configured in ERTM or SM may be operated over AMP logical links. SDP (Service Discovery Protocol)Service Discovery Protocol (SDP) allows a device to discover services supported by other devices, and their associated parameters. For e
27、xample, when connecting a mobile phone to a Bluetooth headset, SDP will be used for determining which Bluetooth profiles are supported by the headset (Headset Profile, Hands Free Profile, Advanced Audio Distribution Profile (A2DP) etc.) and the protocol multiplexer settings needed to connect to each
28、 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)/vichitra Cable replacement protocols(RFCOMM)Radio frequency communications (RFCOMM) is a cable replacement protoco
29、l 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.RFCOMM provides a simple reliable data stream to the user, similar to TCP. It is used directly by many telephony related p
30、rofiles as a carrier for AT commands, as well as being a transport layer for OBEX over Bluetooth. Telephony control protocols (TCP).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 B
31、luetooth 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 protocolsAdopted protocols are
32、defined by other standards-making organizations and incorporated into Bluetooths 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 li
33、nk. TCP/IP/UDP:For communicating with the device connected to Internet. Object Exchange Protocol (OBEX): Session-layer protocol for the exchange of objects, providing a model for object and operation representation. It uses the client-server mode. Wireless Application Environment/Wireless Applicatio
34、n 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.TechnologySPECTRUM AND INTERFERENCEBluetooth technology operates in the unlicensed industrial, scientific and medical (ISM
35、) 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.SIM frequency band is open to all radio system, So the use of a certain frequency band will meet unpredict
36、able interference sources. Therefore, Bluetooth designs special fast acknowledge and frequency hopping technique to ensure the stability of link. Frequency hopping technique to divide the band into many frequency hopping channels, in a connection, radio transceiver “jump” from a channel to another c
37、onstantly according to certain code sequence. Only sender and receiver communicate according to this law, and the rest of interference may not press the same rule. The instantaneous bandwidth of Frequency hopping is very narrow, but through the spread spectrum technology it can make the narrow bandw
38、idth one hundred times expanded into wideband, making the influence of interference may become very small. Comparing to other systems that work in the same frequency band, frequency hopping of Bluetooth works faster, data packet of Bluetooth is shorter, which make it more stable than the otherERROR
39、CORRECTIONBluetooth supports circuit switching and packet switching two techniques, and defines two types of link connection, namely connection-oriented synchronous link (SCO) and connectionless-oriented asynchronous link (ACL)Bluetooth use three error correction models: 1/3 Forward Error Correction
40、 (FEC), 2/3forward Forward Error Correction and Automatic Repeat Request (ARQ). Purpose to the error correction is to reduce the possibility of retransmission, while at the same time increase the extra expenses, but in a reasonable errorless environment, redundant bids will reduce output. So the pac
41、ket definition itself also keeps flexible ways. Hence the software can be defined whether to adopt FEC. In general, when the channel noise is large, Bluetooth system will uses FEC, in order to ensure the quality of communication: as to SCO link, 1/3 FEC is used; 2/3 FEC is used in ACL link. In unnum
42、bered ARQ, the data send in a time slot must receive a confirmation of receipt in the next time slot. Only when the data is checked to be without mistake after header error detection and CRC at receiver will the confirmation sent to sender, or an error message will be sent back.RANGERange is applica
43、tion specific and although a minimum range is mandated by the Core Specification, there is not a limit and manufacturers can tune their implementation to support the use case they are enabling. Range may vary depending onclass of radio used in an implementation: Class 3 radios have a range of up to
44、1 meter or 3 feet Class 2 radios most commonly found in mobile devices , have a range of 10 meters or 33 feet Class 1 radios used primarily in industrial use cases , have a range of 100 meters or 300 feetPOWERIn order to make a Bluetooth equipment can also be in connection even in a very low power s
45、tate, Bluetooth stipulates three energy saving state: Park state, Hold state and Sniff state. The energy saving efficiency of these states declines one by one. The most commonly used radio is Class 2 and users 2.5mW of power. Bluetooth technology is designed to have very low power consumption. This
46、is reinforced in the specification by allowing radios to be powered down when inactive.The Generic Alternate MAC/PHY in Version 3.0 HS enables the discovery of remote AMPs for high speed devices and tums on the radio only when needed for data transfer giving a power optimization benefit as well as a
47、iding in the security of the radios.Bluetooth low energy technology, optimized for devices requiring maximum battery life instead of a high data transfer rate, consumers between 1/2 and 1/100 the power of classic Bluetooth technology.SECURITYMobility and open of Bluetooth system makes safety problem
48、s extremely important. Although the frequency modulation technique used by Bluetooth system has already provided a certain security, but Bluetooth system still need safety management to link layer and application layer. In link layer, Bluetooth system provides authentication, encryption and key mana
49、gement, and other functions. Each user has a Personal Identification Number (PIN), which will be translated into 128 bit link key for one-way or both-way certification. Once the authentication finished, link will use encryphon key to encrypt. The link layer security mechanism provides a great deal of certification schemes and a flexible encryption scheme (means allow the consult
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