Bluetooth Stack Architecture
The protocol stack makes up the core portion of the Bluetooth implementation. This stack enables devices to locate each other and establish a connection. Through this connection, devices can exchange data and interact with one another through various applications.
The following illustration shows the supported layers within the Bluetooth stack.
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OBEX (Object Exchange) is an object exchange protocol that is implemented on top of Winsock over Bluetooth and IRDA transports.
TDI (Transport Driver Interface), in the Microsoft® Windows® CE .NET operating system (OS) architecture, is an interface that serves as an adaptation layer to Winsock-based user APIs. It isolates the highly asynchronous callback-based architecture of the stack presenting a Windows Sockets Specification 1.1 interface.
COM Port Emulation, in Windows CE, enables virtual COM ports to be created over RFCOMM channels. It hosts dial-up and LAN access profiles.
SDP (Service Discovery Protocol) is a Bluetooth service discovery protocol that handles publishing and discovery of services running on top of the Bluetooth stack.
RFCOMM (Serial Cable Emulation Protocol) is Bluetooth's adaptation of the TS07.10 protocol. It serves as a base for COM port emulation facilities and derived point-to-point protocols. Multiplexing and flow control between devices and applications are also implemented here.
L2CAP (Logical Link Control and Adaptation Protocol) is a lower connection-based Bluetooth communication protocol that implements multiplexing. L2CAP does not implement flow control. It relies on a reliable device-to-device baseband link provided by Bluetooth hardware.
HCI (Host Controller Interface) is a basic interface to Bluetooth hardware, responsible for controller management, link establishment, and maintenance.
HCI Transport Layer is a transport layer that delivers HCI commands to the Bluetooth hardware.
LMP (Link Manager Protocol) is the protocol that handles link establishment between Bluetooth devices, which include authentication and encryption.
BB (Baseband) enables the physical radio frequency (RF) link between Bluetooth units that form a piconet.
Each layer, with the exception of the HCI transport, is implemented as a separate entity that exposes its interfaces up and down through tables of callbacks. Each interface is well defined. There are no other interrelationships between parts of the stack; every layer is replaceable.
For more information about the Bluetooth stack implementation in Windows CE, see Bluetooth Stack Implementation in Windows CE.
See Also
Last updated on Thursday, April 08, 2004
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