Bluetooth Protocol Stack Diagram

Bluetooth

The Original idea behind Bluetooth was to connect mobile phones with peripheral devices through a wireless connection. So, The IEEE committee and Bluetooth SIG (Special Interest Group) came into harmony to promote both technologies at the later stage of the 20th century. Bluetooth Technology was developed by Ericsson Mobile Communications in the 1990s. It is named after the 10th-century Danish king Harald “Bluetooth” Gormsson, who united Denmark and Norway.

Features of Bluetooth Technology

i. It should be noted that the Bluetooth specification is for a full system from the physical layer to the application layer. IEEE 802.15 committee is standardizing only the physical layer and data link layer.

ii. Bluetooth is an open-wireless standard technology. So, it is used to send or receive data to connected devices present across a certain distance using the 2.4 GHz ISM spectrum band (2400 to 2483.5 MHz).

iii. In Bluetooth, the wireless signals transmit the data and files over a short distance, typically up to 30 feet or 10 meters. The latest version of Bluetooth 5.0 can exchange data in the range of about 40-400 meters.

iv. The average speed of data transmission in Bluetooth technology is around 1 Mbps to 3 Mbps. The latest version of Bluetooth 5.0 provides the average speed of data transmission is around 10 Mbps – 24 Mbps.

Bluetooth Protocol Stack

The basic unit of Bluetooth is piconet. A piconet contains a master node and up to seven active slave nodes within a distance of 10m. A collection of piconets connected by a bridge node in a large room is often known as Scatternet.

Bluetooth Protocol Stack in Mobile Computing

Bluetooth Protocol Stack can be divided into four basic layers, These are:
i. Base-band: The baseband enables the physical radio frequency (RF) link between units forming a piconet. This layer uses inquiry and paging procedures to synchronize the transmission with the different Bluetooth devices.

ii. Link Manager Protocol (LMP): When the Bluetooth devices come within each other’s radio range, the link manager engages itself in the peer-to-peer message exchange. These perform various security functions stuffing from authentication to encryption.

iii. Logical Link Control and Adaptation Protocol (L2CAP): This layer is responsible for the segmentation of large packets and the reassembly of fragmented packets. L2CAP is also responsible for multiplexing Bluetooth packets from different applications.

iv. Service Discovery Protocol (SDP): SDP enables a Bluetooth device to join a piconet. SDP uses a client-server model where the server has a list of services defined through service records.