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The Evolution of Bluetooth® to Becoming a Low-Power Protocol

Telink Staff

January 13, 2022

Standards

Driver uses Bluetooth on smartphone in car

Bluetooth® has evolved through many versions. Version 4.0 and beyond offer reduced power consumption without compromising on range. See the difference with Bluetooth® LE. 

Three factors determine the performance of a device over a network: range, data rate, and power consumption. Power consumption has constantly been a problem in IoT, but now, low-power standards offer a reprieve. These protocols can achieve long battery life and an ideally sufficient range. Because the focus is on long battery life without compromising on range, low-power protocols have a low data rate, essentially exchanging data rate for battery life.

Because lower-power protocols are used to connect devices for the purpose of sharing sensor data, data rate tends to already be low, compared to uses like internet surfing or watching videos. Bluetooth® Low Energy (LE) is a milestone of Bluetooth technology’s evolution and offers many advantages when compared to Bluetooth® Classic for many IoT applications. Below, we show you the difference that you can experience with Bluetooth LE. 

Evolution of Bluetooth® as a Standard

The Bluetooth Classic radio is a low-power radio that streams data over 79 channels in the 2.4 GHz unlicensed industrial, scientific, and medical (ISM) frequency band. Mainly used to enable wireless audio streaming, Bluetooth Classic supports point-to-point device communication and has become the standard radio protocol behind wireless speakers, wearables, and in-car entertainment systems.

Standard Bluetooth Classic technology uses radio waves in the 2.4 GHz ISM frequency band and is sent in the form of packets to one of 79 channels. The maximum data rate supported by Bluetooth Classic is 3 Mb/s with the EDR PHY. 

On the other hand, a lower-power Bluetooth radio, which was first introduced in the Bluetooth 4.0 standard, has 40 channels and a maximum data rate of 2 Mhz with the LE 2M PHY specified in the Bluetooth 5.0 standard. This new technology is known as Bluetooth Low Energy. 

Because Bluetooth Classic can handle a lot of data, but consumes battery life quickly and costs a lot more, Bluetooth LE is optimal for applications that do not need to exchange large amounts of data and can therefore run on long battery power at a cheaper cost.

The Bluetooth® LE Difference

Bluetooth Low Energy — which used to be known as Bluetooth Smart — is a significant foundation for IoT applications. It enables short-burst wireless connections and uses multiple network topologies, including point-to-point (P2P), broadcast, and mesh. Compared to previous generations of Bluetooth, it also offers improved connectivity and security, additional packet capacity (almost 10 times that of the 4.1 version), and increased data range by 2.5 times, all of which enhance device-to-device communications with more efficient uploads of sensor data logs to a smartphone, the cloud, or an intermediate location on an ISP provider’s servers.

Using the standard Bluetooth 4.2 core specification, Bluetooth LE has a range of 50-150 m with a 1 Mbps data rate. While it has a similar range to Bluetooth Classic, it sees a much reduced power consumption. As such, it’s more suitable for small chunks of data rather than for file transfer. In other words, it focuses on sending smaller bits of data when needed, then it puts the connection to sleep during periods of non-use, whereas with the previous versions of Bluetooth, users had to shut down their hardware when critical data was not being transferred in order to save power. All of this just means that Bluetooth LE has a major advantage in a more personal space context (think mobile computers, mobile phones, and handheld devices).

Bluetooth® LE vs. Bluetooth® Classic

Compared to Bluetooth Classic, Bluetooth LE, introduced in Bluetooth version 4.0, is more prominent in applications where power consumption is crucial (such as battery-powered devices) and where small amounts of data are transferred infrequently (such as in sensor applications). These two types of Bluetooth devices are not compatible with each other: a Bluetooth Classic device cannot communicate directly with a Bluetooth LE device. However, some devices, such as smartphones, allow implementation of both types by creating Dual Mode Bluetooth devices.

Bluetooth Classic is better suited for streaming applications such as audio streaming, file transfers, and headsets, whereas Bluetooth LE is used for sensor data, control of devices, and low-bandwidth applications. Bluetooth Classic is not optimized for low power, but has a higher data rate. Meanwhile, Bluetooth LE, as its name suggests, is meant for low-power, low-duty data cycles. Bluetooth Classic operates over 79 RF (radio frequency) channels and discovery occurs on 32 channels. Bluetooth LE, on the other hand, operates over 40 RF channels with discovery occurring on only three channels, leading to quicker discovery and connections than Bluetooth Classic. 

Bluetooth LE has gone through some major revisions and changes in the short time since its official release in 2010. It has evolved through 4.0, 4.1, 4.2, 5.0, 5.1, and 5.2, and is currently at Bluetooth 5.3, which was released in July 2021. Version 4.0 launched the concept of Low Energy and expanded Bluetooth technology into many types of IoT sensors. Bluetooth 5 introduced many important upgrades to the Bluetooth specification, most of which were focused on BLE. Some of the most important enhancements include twice the speed, four times the range, and eight times the advertising data capacity. 

  • Bluetooth 5.1: Presented by the Bluetooth SIG on January 21, 2019, Bluetooth 5.1 introduces several fixes, enhancements, and new features to improve connection speed and performance and also create new use cases for location and tracking. Angle of Arrival (AoA) and Angle of Departure (AoD) take multiple samples of a signal to determine the signal origin. This makes it possible to discover proximity and direction between two devices with a higher accuracy. 
  • Bluetooth 5.2: The announcement of Bluetooth 5.2 was made alongside the introduction of Bluetooth LE Audio. A major change introduced in version 5.2 is a new feature called Isochronous Channels (ISOC). ISOC sets the foundation for the implementation of LE Audio in Bluetooth LE devices. Bluetooth LE Audio also allows for one audio stream to be picked up by multiple receiving devices. As such, a crowd can all tune in at the same time to an ongoing Bluetooth stream. This feature is also the basis behind Bluetooth audio sharing for synchronized listening. 
  • Bluetooth 5.3: On July 13, 2021, the Bluetooth SIG released version 5.3, which brings four new enhancements and removes one extension from the core specification:
    • Periodic Advertising Enhancement
    • Encryption Key Size Control Enhancement
    • Connection Subrating
    • Channel Classification Enhancement
    • Removal of the Alternate MAC and PHY (AMP) Extension
  • Bluetooth Mesh: Introduced around 2017, Bluetooth Mesh supports M to M mesh network topology. It also enables the creation of large-scale device networks and is ideally suited for control, monitoring, and automation systems where hundreds or thousands of devices need to communicate with one another. Advanced commercial lighting control is one such use case.

Telink Provides Low-Power Solutions

Telink provides our customers with the full range of Bluetooth certifications issued by the Bluetooth Special Interest Group (SIG), including Bluetooth 5.2 and Bluetooth 5.3. As Bluetooth continues to evolve as a standard, we are here to help developers choose the versions that work for you, including low-power protocols that offer a longer battery life, depending on your application’s needs. 

Please visit our wiki to learn more about all our development tools, or ask us a question through our Technical Forum or by contacting us directly today.