Bluetooth 5 vs. Bluetooth 5.1: Key Differences and New Features

This article breaks down the differences between Bluetooth 5 and Bluetooth 5.1, highlighting the new features introduced in the 5.1 version. We’ll also touch on how Bluetooth 5 compares to older versions like 4.2.

Introduction:

• Bluetooth 5.1 was released by the Bluetooth SIG on January 21st, 2019.
• It’s designed to be backward compatible with older Bluetooth versions, including 5.0 and 4.2.
• A key improvement in Bluetooth 5.1 is direction finding. This significantly enhances location accuracy, allowing you to find Bluetooth trackers (like those attached to your keys) with “centimeter-level accuracy.”
• Bluetooth 5.1 improves the advertising mode, enabling smart devices (like thermometers) to broadcast their measurements to other Bluetooth devices without requiring a connection.
• Bluetooth 5.1 focuses on reliability and scalability for Bluetooth devices.
• It allows low-power devices (e.g., smartwatches) to rely on more powerful devices (like smartphones) for some tasks, conserving battery life.
• The handshake process with previously paired devices is faster in Bluetooth 5.1.
• While caching was introduced in earlier versions, Bluetooth 5.1 makes it more efficient.

New Features of Bluetooth 5.1

Here’s a breakdown of the new features that differentiate Bluetooth 5.1 from previous versions:

• Angle of Arrival (AoA) and Angle of Departure (AoD): These are the core of the improved direction-finding capabilities.
• Advertising Channel Index: Enhancements to how advertising channels are used.
• GATT Caching: Improved caching for faster and more efficient GATT (Generic Attribute Profile) operations.
• Minor Enhancements (Batch 1): This includes a collection of smaller improvements:
  • HCI support for debug keys in LE Secure Connections
  • Sleep clock accuracy update mechanism
  • ADI field in scan response data
  • Interaction between QoS and Flow Specification
  • Host channel classification for secondary advertising
  • Allow the SID to appear in scan response reports
  • Specify the behavior when rules are violated
• Periodic Advertising Sync Transfer: Enhancements to periodic advertising features.
• Features added in CSA6 which are integrated in bluetooth v5.1
  • Models
  • Mesh-based model hierarchy

DEPRECATED FEATURES:

• The “Unit keys” feature has been removed in Bluetooth 5.1.

Bluetooth 5 vs. Bluetooth 4.2: Key Differences

The following table highlights the main differences between Bluetooth 5 and Bluetooth 4.2:

References

• BLUETOOTH CORE SPECIFICATION Version 5.1, Vol 1, Part C