Bluetooth 5 and its Role in the Internet of Things

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What is Bluetooth 5?

If you own a modern car or a smartphone, chances are you’ve used Bluetooth at least once in your life. Bluetooth is everywhere: in speakers, wireless headphones, cars, wearables, medical devices, and even shoes!

There are two kinds of Bluetooth devices: one is referred to as Bluetooth Classic (used in wireless speakers, car infotainment systems, and headsets), the other is Bluetooth Low Energy (BLE).

BLE 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 kinds of Bluetooth devices are incompatible with each other (even though they share the same brand and even specification document). A Bluetooth Classic device cannot communicate (directly) with a Bluetooth Low Energy device. This is why some devices such as smartphones choose to implement both types (sometimes called a Dual Mode Bluetooth device), that way they can communicate with both types of devices.

Since many IoT systems involve small devices and sensors, BLE has become the more common protocol of the two (versus Bluetooth Classic) in IoT. In December 2016, the Bluetooth Special Interest Group (SIG), the governing body behind the Bluetooth standard, released Bluetooth version 5.0. A majority of the enhancements and features introduced in this version focused on Bluetooth Low Energy.

What is new in Bluetooth 5.0?

So, what’s new in Bluetooth 5.0 versus the previous versions?

The three main features that were introduced are:

  1. 2x the speed
  2. 4x the range
  3. 8x the advertising capacity

Let’s go over each of these and take look at the potential IoT applications that could utilize them.

Twice the Speed

In older versions of Bluetooth (4.2 and earlier), the data rate for BLE was set at a fixed 1 Mbps. In Bluetooth 5.0, a new mode with a data rate of 2 Mbps is introduced. This new data rate offers a couple of additional benefits as well:

  • Reduced power consumption since the same amount of data is transmitted in less time.
  • Improvement of wireless coexistence because of the reduced radio-on time.

One downside to using the 2Mbps mode is that it has the potential of reducing the range, as the higher speed results in a decrease in radio sensitivity on the receiving end. However, for applications that can sacrifice a bit of range in favor of higher data rate transfer speeds, this mode can prove to be a game changer.

Compared to other low power wireless protocols (e.g. ZigBee, Z-Wave, Thread), BLE offers the highest data rate, even at the original 1 Mbps data rate. With the addition of the new high-speed mode (2 Mbps), more potential IoT applications become more feasible. Examples include low-quality video streaming, audio streaming and short bursts of large data transfers such as images.

Compared to other low power wireless protocols, BLE offers the highest data rate, even at the original 1 Mbps data rate. Click To Tweet

Four Times the Range

Bluetooth 5.0 also introduced a long-range mode that utilizes an error correction technique called Forward Error Correction (FEC). FEC allows the receiver to recover the data from errors that occur due to noise and interference. So instead of requiring retransmission of data when an error occurs, the receiver can recover the originally transmitted data by utilizing the redundancy in the data.

This mode is referred to as the Coded PHY mode (PHY stands for physical radio and refers to the radio interface layer in a network architecture). The obvious benefit of using this new mode is the increased range, with the trade-off being higher power consumption and reduced speed (125 kbps or 500 kbps, depending on the coding level used).

Ranges as far as 800 meters line-of-sight have been recorded while testing with the long-range mode. This makes it possible to use BLE in applications such as ones that require communication with a device hundreds of meters away. Examples include long-distance remote control devices, home automation, and industrial applications.

Eight Times the Advertising Capacity

In BLE, there are three main states a device can operate in. It can either be Advertising, Scanning or Connected. To get two BLE devices connected, one device has to advertise and the other has to scan for it, and then initiate the connection. Advertising essentially involves broadcasting packets which allow another scanning device to discover them. The scanning device may then decide to initiate a connection if the advertisement packets indicate that the advertising device allows it.

In earlier versions of Bluetooth, the advertising data payload size was capped at 31 bytes. In Bluetooth 5.0, a new advertising mode is introduced: Extended Advertising. Extended Advertising allows sending up to 255 bytes of payload data per packet instead of the original 31 bytes limit.

Advertising is used in all BLE devices, but one prominent application that utilizes this state exclusively is Beacon technology. Beacon devices stay in the Advertising state and simply broadcast data for others to explore and read data from. With increased advertising data capacity in Bluetooth 5.0, Beacons can now transmit much more data unlocking new IoT applications and use cases.

Conclusion

As we can see, Bluetooth 5.0 introduced a few features that can be applied to a wide range of potential IoT applications. However, there are a few important key points to keep in mind:

  • The new long-range and high-speed modes are optional features per the official Bluetooth specification, so a chipset or device that claims Bluetooth 5 support may not support either of these new modes.
  • To be able to utilize these new features, the two BLE devices communicating with each other need to support Bluetooth 5 and support the feature of interest. For example, to be able to utilize the long-range mode in transmitting sensor data over long distances between a sensor device and a smartphone, both the sensor device and smartphone need to support both Bluetooth 5 and the long-range mode.
  • Smartphones are still slow to support Bluetooth 5 and its new features. Even when the new hardware supports it, the APIs need to allow the mobile developer to utilize these features.

With that said, however, the potential new IoT applications that Bluetooth 5’s features introduce simply make its wide adoption inevitable, on both the mobile and embedded side!