The link manager, located on top of the link controller, controls setup, authentication, link configuration, and other low-level protocols. Together, the baseband and the link manager establish connections for the network.

The host controller interface (HCI) communicates the lower-layer protocols to the host device(Like mobile phone, hand held PC etc).The host contains a processor.

L2CAP: it supports the upper-layer protocols and communicates with the lower layers. The Higher/upper-layer protocols consist of service-specific applications that must be integrated into the host application as explained above. RFCOMM protocol, which allows for the emulation of serial ports over the L2CAP, which is also an important part of Bluetooth.

The Service Discovery Protocol (SDP) gives the required services and the properties and characteristic of the service that a particular Bluetooth device is made for.

The ACL Link: Bluetooth uses five logical channels to support transferring of information between devices:

Core Protocols in Bluetooth:

Baseband: The Baseband and Link Control layer enables the physical RF link between Bluetooth forming a piconet. It provides two different kind of physical links with their corresponding baseband packets, Synchronous Connection-Oriented and Asynchronous Connectionless which can be transmitted in a multiplexing manner on the same RF link.Asynchronous Connectionless (ACL) packets are used for the transmission of data only while Synchronous Connection-Oriented can contain either audio or a combination of audio and information.

Link Manager Protocol: The link manager protocol is responsible for link set-up between Bluetooth devices. This includes setting up of security functions like authentication and encryption by generating, exchanging and checking of link and encryption keys and the control, negotiation of baseband packet sizes and duty cycles of the Bluetooth radio device, and the receiving device on the other end.

Logical Link Control and Adaptation Protocol: The Bluetooth logical link control and adaptation protocol (L2CAP) adapts upper layer protocols over the baseband. It can be thought to work in parallel with LMP in difference that L2CAP provides services to the upper layer when the payload data is never sent at LMP messages.

Service Discovery Protocol: Using SDP, device information, services and the characteristics of the services can be queried and after that, a connection between two or more Bluetooth devices can be established.