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