Bluetooth® Low Energy (LE) for wearables, peripherals and IoT

Bluetooth® LE, with its extremely low power consumption, very fast pairing and worldwide use of the 2.4 GHz band, addresses many applications requiring short-range low-power data connectivity

The Bluetooth® LE technology has been adopted in Bluetooth® specification 4.0 to achieve an ultra-low-power solution particularly for peripherals and wearables used in a wide range of applications such as medical devices or automotive applications. With this version, Bluetooth® LE has a maximum data rate of 1 Mbit/s, consuming between 0.01 to 0.5 watts, thus using around half the power to provide approximately 33 % of the data rate of Bluetooth® Classic.

With Bluetooth® 5, the application range was further expanded in the internet of things (IoT) space with features for higher data rate of 2 Mbit/s, long-range coding and additional advertising capabilities. The number of devices per ad hoc network was increased. In conjunction with the Bluetooth® Mesh specification, this opens new opportunities in the home/building automation and industrial applications area.

Bluetooth® 5.1 improved the direction finding capabilities with features like Angle of Arrival (AoA) and Angle of Departure (AoD), and the latest version 5.2 was adding native low energy audio support and a smart power control functionality.

Your Bluetooth® LE test challenges

There are several factors that influence the overall communications performance. These include antenna design, power supplies, coexistence issues with other wireless communications chips such as LTE and WLAN, and the final housing. During and after the design stage, it is important to conduct tests to ensure that the transmitted information is correct.

Tests such as verifying the test packet structure, output power, modulation characteristics and carrier frequency error are necessary. Bluetooth® SIG has defined related test cases for the Bluetooth® qualification and has specified a direct test mode (DTM) to control transmitter and receiver tests via a wired control interface. This test mode is activated via external commands, which can be a bit cumbersome, especially for test situations where no direct access to the DUT is possible.

However, the industry is also looking for possibilities to allow easy-to-use over-the air testing of the Bluetooth® LE devices. Essentially, there are two approaches: to use the always-active advertising channels to perform RX and TX measurements, or to use standard Bluetooth® LE signaling for testing the device.