Bluetooth Low Energy (LE)

Bluetooth Low Energy (LE), introduced with Bluetooth 4.0 in 2010, is a wireless communication protocol optimized for short-range, low-power data exchanges. Unlike Bluetooth Classic, LE is tailored for battery-powered devices and intermittent transmissions, making it ideal for wearables, sensors, and IoT applications.

Frequency & Modulation

Bluetooth LE operates in the 2.4 GHz ISM band, using 40 channels with 2 MHz spacing:

• Data Channels: 37

• Advertising Channels: 3

The modulation scheme is GFSK (Gaussian Frequency Shift Keying). Several physical layer (PHY) options are defined:

• LE 1M PHY: 1 Mbit/s data rate (default)

• LE 2M PHY: 2 Mbit/s for faster throughput

• LE Coded PHY: 125 kbit/s (S=8) or 500 kbit/s (S=2) for extended range, using forward error correction (FEC)

These PHYs provide flexibility between speed and range, while maintaining energy efficiency.

Typical Applications

Bluetooth LE is used in applications that require minimal power consumption and short, burst-type communication:

• Health & Fitness: Heart rate monitors, temperature sensors, fitness trackers

• Industrial & Smart Home: BLE beacons, occupancy sensors, lighting control

• Peripherals: BLE HID for keyboards and mice

• Broadcasting: Beaconing and extended advertising (Bluetooth 5 and later)

The main protocol used for data exchange is the Generic Attribute Profile (GATT), enabling structured communication via predefined services and characteristics.

Differences from Bluetooth Classic

Compared to BR/EDR, Bluetooth LE offers:

• Significantly lower power consumption

• Optimized connection procedures and sleep modes

• No support for legacy profiles like A2DP or SPP

• Native support for one-to-many advertising and GATT-based services

While LE does not match Classic in continuous data throughput, it excels in efficient short exchanges.

Relevance for Testing & Certification

Bluetooth LE devices must comply with applicable regional radio standards, including:

• Europe: ETSI EN 300 328

• USA: FCC §15.247

• International: ISED, MIC, etc.

Although LE uses the same frequency band as Classic, differences in channel structure and timing behavior must be considered during compliance testing.

In addition to regulatory compliance, Bluetooth SIG Qualification is mandatory for any product using Bluetooth technology and marketed under the Bluetooth name – regardless of whether standard profiles or custom GATT services are used. Only SIG members may use the Bluetooth name and logo after successful qualification and listing.