This page provides a brief introduction to the Bluetooth^® Low Energy (BLE) Specification.

What is Bluetooth?

Bluetooth is a set of specifications for common short-range wireless applications, covering radios, protocols, and profiles.

The Bluetooth Core Specification is maintained by the Bluetooth Special Interest Group (SIG).

Features of the "classic" Bluetooth radio include:

• 2.4 GHz ISM band, 1 Mbps, GFSK, 4PSK, or 8PSK
• 1 MHz channel spacing, with frequency hopping
• Adaptive frequency hopping, for co-existence with Wi-Fi^®
• Up to 100 mW, more than 100 m range is possible

BLE

An extension to the Bluetooth 4.x Core Specification, targeted to supporting Internet-of-Things (IoT) applications:

• Mostly new physical layer. Some parts derived from the Basic Rate (BR) radio.
• New advertising mechanism, for ease of discovery and connection.
• Asynchronous connection-less MAC, used for low latency, fast transactions (i.e., 3 mS from start to finish).
• New Generic Attribute Profile (GATT) to simplify devices and the software that uses them.
• Asynchronous Client/Server Data model.

Basic Tenets

Operation Using Button-cell Batteries

• Low peak current
• Low energy (Power*Time)
  • Small Packet Size
  • Minimize Duty Cycle & Latency

Asymmetry

• The device with the lower energy source is given less to do

IoT Ready

• Client/Server Data model
  • Things have data
  • Web services want this data

Bluetooth 4.2: Key Improvements for BLE

Faster Data Synchronization/Firmware Updates

• In 4.2, there is up to 2.5x higher throughput with a huge packet data capacity increase - nearly 10x more than earlier versions of BLE.

Highly Secure

• Features Federal Information Processing Standard (FIPS)-compliant encryption
• LE Security Mode 1, Level 3, and 4
  • Meets the requirements of the Payment Card Industry (PCI) for Pin Transaction Security (PTS) Point of Interaction (POI) financial transactions, where BT 4.2 must be used and the device must support Security Mode 1, Level 3, or 4.

Designed for Exposing State

What kinds of data transfer are most suited to BLE?

• Small, discrete data transfers
• State information, triggered by local events
• Not streaming

Protocol Stack

The following diagram depicts the architecture (major layers) of the BLE protocol stack. Please select the links below to jump to the specific sections (follow the menu on the left-hand side for further navigation):

• Controller
• Host
• Application