* Question

What kinds of physical connections are provided by baseband data packets?

* Answer

In Bluetooth systems, the baseband layer supports two types of physical connections, each optimized for different traffic patterns and quality-of-service requirements.

1. SCO (Synchronous Connection-Oriented) Link

A circuit-switched, periodic connection used for real-time, delay-sensitive data.

Key Features

• Fixed transmission intervals
• Guaranteed bandwidth
• Low latency
• Typically used for voice or audio channels (e.g., classic Bluetooth headset audio)

SCO links deliver baseband packets at regular time slots, ensuring continuous data flow.

2. ACL (Asynchronous Connection-Less) Link

A packet-switched connection used for general data communication.

Key Features

• Flexible, asynchronous transmission
• Higher throughput than SCO
• Retransmissions supported for reliability
• Suitable for bulk data, control messages, and non-real-time applications

Examples include file transfer, device configuration, or general application data.

Summary

Baseband data packets support two physical connection types:

• SCO link– synchronous, low-latency, real-time communication
• ACL link– asynchronous, high-throughput, best-effort data transfer

These two link types form the foundation of Bluetooth’s physical transport for audio, control, and data communication.