Bluetooth Technology Architecture

Bluetooth

As you already know that Bluetooth is a wireless LAN technology designed to connect devices of different functions such as telephones, notebooks, computers (desktop and laptop), cameras, printers, coffee makers, and so on. Bluetooth makes its own spontaneous network whenever we need it i.e. Bluetooth is a kind of Ad-Hoc network. This network made by different devices is known as PICONET.

A Bluetooth device has a built-in short-range radio transmitter. The current data rate is 1 Mbps with a 2.4-GHz bandwidth. This means that there is a possibility of interference between the IEEE 802.11b wireless LANs and Bluetooth LANs


History:
 Bluetooth was originally started as a project by the Ericsson Company. It is named for Harald Blaatand, the king of Denmark (940-981) who united Denmark and Norway. Blaatand translates to Bluetooth in English.

Bluetooth defines two types of network :
1. PICONET :

A Bluetooth network is called a piconet, or a small net. A piconet can have up to eight stations, one of which is called the primary (or Master "as sir told us") the rest are called secondaries("Slaves  ;) "). Now the main thing is all the secondary stations synchronize their "clocks" and "hopping sequence" with the primary. Note that a piconet can have only one primary station. The communication between the primary and the secondary can be one-to-one or one-to-many.
A piconet can have a maximum of "seven" secondaries, an additional "eight" secondaries can be in the "parked state". A secondary in a parked state is synchronized with the primary, but cannot take part in communication until it is moved from the parked state. Because only eight stations can be active in a piconet, activating a station from the parked state means that an active station must go to the parked state.

2. SCATTERNET
Piconets can be combined to form what is called a scatternet. A secondary station in one piconet can be the primary in another piconet. This station can receive messages from the primary in the first piconet (as a secondary) and, acting as a primary, deliver them to secondaries in the second piconet. A station can be a member of two piconets.


Bluetooth Architecture:

Little More : 

L2CAP: (Imp ;) )
Header Packet Format:

L2CAP
The Logical Link Control and Adaptation Protocol, or L2CAP (L2 here means LL), is roughly equivalent to the LLC sublayer in LANs. It is used for data exchange on an ACL link.In L2CAP header 16-bit length field defines the size of the data, in bytes, coming from the upper layers.The channel ID (CID) defines a unique identifier for the virtual channel created at this level (see below).

The L2CAP has specific duties:
1. Multiplexing.
2. Segmentation and reassembly
3. Quality of service (QoS)
4. Group management.