The Bluetooth Architecture

1. ® The Bluetooth Architecture APIs, L2CAP, Link Management, Baseband, and the Radio

2. API 2 API 3 API ... The Bluetooth ArchitectureFive Layers to Wireless Communications Application Program Interface libraries Logical Link Control & Data Adaptation Protocol Physical link control Data processing & transmission management Transmission/reception • Bluetooth is enabled through 5 layers of software and hardware • These layers distribute functional responsibility • The bottom layers handle the lowest level details • Progressively higher layers handle ever more general concerns API 1 API n L2CAP (data) Control Audio Link Manager Baseband RF (radio and antenna)

3. A P I s ... SDP API ... API ... Application Program Interface Libraries Host Application(s) TCS API ... • APIs connect the host system’s application software to the Bluetooth communications sub-system • New capabilities that Bluetooth enables are supported through new APIs • Telephony Control protocol Specification (TCS) • Service Discovery Protocol (SDP) • Etc. Bluetooth sub-system

4. A P I s ... Application Program Interface Libraries Host Application(s) Legacy APIs UDP TCP AT Commands OBEX • RFCOMM and other APIs on PCs provide support for legacy communications capabilities • PPP (TCP/IP) • OBEX (IrDA) • etc. IP RFCOMM Bluetooth sub-system

5. L2CAP Logical Link Control and Adaptation Protocol • The L2CAP performs four major functions • Managing the creation and termination of separate, independent, Logical Links for each desired connection • Including support for broadcast 1-to-many communications • Dictating and enforcing QoS requirements • Data adaptation between application native and Bluetooth baseband formats for each connection • Multiplexing to allow multiple concurrent connections over the single common radio interface

6. L2CAP API 1 API 2 API ... Logical Link Control and Adaptation Protocol • Channel ... • Source • Destination(s) • Protocol • QoS L2 CAP • The L2CAP creates and manages independent Logical Links through structures called “Channels” • Channels define the relationship between a specific host application and a specific remote device (or group of devices) and another specific application • Defines the source, destination(s), protocol, QoS, etc. • Channel 1 • Source • Destination(s) • Protocol • QoS • Channel 2 • Source • Destination(s) • Protocol • QoS

7. L2CAP Logical Link Control and Adaptation Protocol (2) API 2 API 1 API ... L2 CAP Channels • The L2CAP also adapts and multiplexes data to and from the APIs • Segmentation And Reassembly (SAR) adapts data streams to/from their native formats for Bluetooth’s baseband • Multiplexing enables simultaneous transmission of multiple channels over the radio interface SAR Multiplexing

8. Link Manager Link Manager • QoS negotiation • Pairing and Authentication • Definition and maintenance of timing parameters • Link monitoring and fault handling • Etc. • The Link Manager is responsible for the physical link resources in the system and performs all link creation, management, and termination operations • Establishes outbound links upon request from the L2CAP and confirms successful completion • Intercepts and processes inbound Link Control operations from other devices independently • Clock synchronization updates etc. • Monitors on-going link status and closes any link that fails with the L2CAP

9. Baseband Baseband Bitstream Processing • Packet construction/deconstruction • Error correction encoding/decoding • Encryption/decryption • Data whitening/de-whitening • Sequence numbering and error handling • The Baseband controller is responsible for all bitstream processing immediately before and after RF transmission • The typical processing dataflow is as follows: Packet Sequence Numbering Header Error Correction Header Whitening Header FEC Encoding Payload CRC Generation Payload Encryption Payload Whitening Payload FEC Encoding RF Interface Packet ACK/NAK Payload Error Checking Payload Decryption Payload De-whitening Payload FEC Decoding HEC Checking Header De-whitening Header FEC Decoding Mandatory Optional

10. Baseband Baseband • The Baseband controller is also responsible for a number of low level operational responsibilities • Inquire scanning and response • Page scanning and response • Hold, Sniff, Park, and Sandby state management • Frequency hopping calculation • Etc.

11. Radio Radio • The Bluetooth radio performs all D/A and A/D processing of the I/O data stream • Accepts and supplies digital data from/to the baseband • Provides and accepts an analog signal to/from the antenna

12. API 2 API 3 API ... Bluetooth System ArchitectureFully Integrated Implementation Host application Application Program Interface libraries Logical Link Control & Data Adaptation Physical link control Data processing & transmission management Transmission/reception • In highly integrated systems these layers can all be co-resident on the same device • Even as far as both the host application and Bluetooth protocol stack running on the same microcontroller Application API 1 API n L2CAP (data) Control Audio Integrated device Link Manager Baseband RF (radio and antenna)

13. API 2 API 3 API ... Audio Control Bluetooth System ArchitectureModular Implementation Host application Application Program Interface libraries Host HCI driver Host HCI hardware Bluetooth module HCI hardware HCI firmware Logical Link Control & Data Adaptation Physical link control Data processing & transmission management Transmission/reception Application HCI driver API 1 API n Host system Host Controller Interface Transport Bus Host Controller Interface HCI firmware L2CAP (data) Bluetooth module Link Manager Baseband RF (radio and antenna)