| Bluetooth is the name for an emerging | | | | The L2Cap supports upper layer protocols and |
| technology that uses short-range radio links | | | | enables communication with the lower layers. |
| instead of cables to connect portable | | | | The higher-upper layer protocols are often |
| electronic devices. This allows a wide range | | | | very specific tasks and applications that |
| of devices to communicate with one another | | | | require integration with the lower layer |
| without actually being physically connected | | | | applications. The ability of all these |
| to one another. | | | | components to work together and communicate |
| | | | adequately is very important to Bluetooth |
| Some of the most notable features of | | | | technology. |
| Bluetooth technology are the facts that it is | | | | |
| relatively inexpensive (this is first and | | | | Core Protocols in Bluetooth technology: |
| foremost for many potential consumers); it is | | | | |
| not extremely fragile, it is very user | | | | 1) Baseband. This layer combined with the |
| friendly, and has low power consumption. | | | | link control layer enables an RF link to form |
| Bluetooth can be used to create wireless | | | | while offering two distinct physical links |
| Personal Access Networks (PANs) while | | | | with corresponding baseband packets. These |
| offering fast and reliable transmission of | | | | links are Synchronous Connection-Oriented and |
| both voice and data. Bluetooth offers | | | | Asynchronous Connectionless. Synchronous |
| wireless access to the Internet (for home | | | | Connection-Oriented connections can contain |
| access as well as laptops, PDAs, and other | | | | either audio or a combination of data and |
| hand held devices), cell phone services, and | | | | audio while Asynchronous Connectionless |
| local access networks. | | | | packets can only be used for the purpose of |
| | | | transmitting data. |
| A complete Bluetooth system requires an RF | | | | |
| portion in order to send or receive data; a | | | | 2) Link Manager Protocol. This is responsible |
| module for processing, a memory module, and | | | | for establishing links between Bluetooth |
| an interface to the electronic device it is | | | | devices including but not limited to security |
| to communicate with (such as a phone, Palm, | | | | functions such as authentication and |
| or camera). | | | | encryption keys as well as the negotiation |
| | | | duty cycles for the Bluetooth device and the |
| The lower-layer protocols can typically be | | | | device on the receiving end. |
| found within the baseband module and the host | | | | |
| processor must support the protocols of the | | | | 3) Logical Link Control and Adaptation |
| upper-layer. Simply put, the RF-baseband | | | | Protocol. This adapts the upper layer |
| solution supplies the means necessary in | | | | protocols over the baseband. |
| order to communicate with the host. This | | | | |
| additionally requires an interface by which | | | | 4) Service Discovery Protocol. This allows |
| they can connect as well as the 'upper-layer' | | | | device information, services and |
| protocols in order to actually apply the | | | | characteristics of services to be queried. |
| applications the product is designed to | | | | Once queried, a connection can be made |
| support. | | | | between two or more Bluetooth devices. |
| | | | |
| The higher upper layers of Bluetooth | | | | Telephony and Cable Replacement Protocols: |
| technology are referred to as Bluetooth | | | | |
| Profiles. These profiles are literally a set | | | | 1) Telephony Control Protocol. This is a bit |
| of protocols that are optimized in order to | | | | oriented protocol that defines the control |
| complete specific tasks or applications. If | | | | signal for the call and establishes speech |
| you wish to share files between two linked | | | | and data cells between the devices. |
| devices they must be compatible devices that | | | | |
| have similar applications across the spectrum | | | | 2) RFCOMM. This is a serial line emulation |
| of devices. | | | | protocol. It is based on European |
| | | | Telecommunications Standardization |
| The Bluetooth stack has the following | | | | Institute's specifications and emulates |
| components: | | | | control over Bluetooth baseband. This |
| | | | provides not only transport capabilities but |
| 1) RF portion. This is necessary for | | | | also allows for upper level services that use |
| reception and transmission. | | | | serial lines as transport mechanisms. |
| | | | |
| 2) Baseband portion. | | | | Adopted Protocols: |
| | | | |
| 3) Link Control Unit | | | | 1) PPP: PPP is the point-to-point protocol. |
| | | | PPP Networking is the act of taking IP |
| 4) Link Manager. This supports lower layer | | | | packets from the PPP layer and putting them |
| protocols. | | | | on the Local Access Network. |
| | | | |
| 5) Interface. This allows a connection to the | | | | 2) TCP/UDP/IP: TCP/IP/PPP this is used for |
| host device. | | | | all Internet bridge purposes. It is also |
| | | | available as transport for the WAP. |
| 6) Host processor. This will support upper | | | | |
| layer protocols. | | | | 3) OBEX Protocol. This is a session protocol |
| | | | that is designed to exchange data simply and |
| 7) L2Cap. This also supports upper layer | | | | automatically. |
| protocols. | | | | |
| | | | Advantages: |
| The Radio Frequency (RF) supplies the Digital | | | | |
| Signal Processing (DSP) element to the system | | | | Bluetooth technology makes the use of |
| while the baseband microcontroller processes | | | | peer-to-peer connectivity simpler by enabling |
| the signals. The link controller supports the | | | | all manner of devices to communicate freely |
| link manager and controls the baseboard | | | | and automatically. Bluetooth also allows for |
| functions by sending and receiving data, | | | | fast, secure voice and data transmissions. |
| identifying the device sending data, | | | | While the range for connectivity is only |
| performing authentication, and determining | | | | about 30 feet, line of sight is not necessary |
| the frame to which the transmission should be | | | | for the signals to be received and |
| sent. The link controller also directs the | | | | transmitted. |
| way devices communicate with each other as | | | | |
| well as enabling the power saving sleep mode | | | | Bluetooth is also capable of functioning in |
| when not being directly used. | | | | noisy radio environments while ensuring |
| | | | audible voice transmissions even in less than |
| The link manager is responsible for setup, | | | | ideal situations. It can correct data through |
| authentication, the configuration of links, | | | | use of error correction methods while |
| and other lower layer protocols. The baseband | | | | providing a high transmission rate. You also |
| and link manager work together in order to | | | | have the ability to use encryption in order |
| establish connections for the network. | | | | to provide added layers of security. |
| | | | |
| The Host Controller Interface (HCI) allows | | | | Bluetooth may also be used to create ad hoc |
| the communication of lower layer protocols to | | | | networking among personal devices in order to |
| the host (which contains a processor) device. | | | | quickly exchange information. |