Bluetooth in IoT

What is Bluetooth?

Bluetooth (IEEE Standard 802.15.1) is a wireless communication standard which allows devices to connect and exchange data with each other.

Operating within the Industrial, Scientific and Medical (ISM) radio bands, at 79 different frequencies (channels) between 2.4 to 2.485 GHz, Bluetooth uses UHF (Ultra-High Frequency) short-wavelength radio waves to transmit and receive information over short distances (up to 100m), providing us with the opportunity to create our own Personal Area Networks (PANs) with our favourite devices.

How does it work?

Although both Bluetooth and WiFi work between 2.4 and 2.485 GHz (ISM radio bands), Bluetooth typically uses a symmetric "master-slave" connection with one device connecting to another or one device connecting to multiple devices (up to 7), creating a small network which is called "piconet".

This kind of connection is usually called "master-slave" connection.

A good example of this "master-slave" relationship is the communication between our personal computer and other devices like a wireless keyboard, mouse, speaker, etc.. When the Bluetooth function is enabled the devices make themselves visible by broadcasting the signal around them. After establishing permission that the devices can talk to each other by following the process called "pairing", we can then connect the devices and start the communication.

Bluetooth Low Energy (BLE)

There are two types of Bluetooth: The Bluetooth Classic that everyone is familiar with and the Bluetooth Low Energy (BLE) which was released later in 2011 (Bluetooth version 4.0).

Whilst the Bluetooth Classic was created to allow the devices to communicate with each other, exchanging high amount of data with less power than the WiFi, BLE was introduced as a game changer version of Bluetooth which was intended to offer considerably reduced power consumption and cost, while maintaining a similar communication range.

That means that BLE is great for periodic transmissions of small amounts of data when used in battery powered products like industrial monitoring sensors, and certain connected medical devices like blood pressure monitors as well as other wearable devices.

Bluetooth 5.0

Bluetooth 5.0 is the latest big version of Bluetooth and has already brought many changes.

It is mainly focused on BLE and it promised to have double the speed (up to 2 Mbps), four times the range, increasing the distance up to 240m and being capable of transferring eight times the amount of data compared to the previous version 4.2.

Since Bluetooth shares the 2.4 GHz ISM band with other wireless standards like Wi-Fi or Zigbee it has not been so difficult to have signal interference.

The improved version 5.0 comes with new features allowing better wireless coexistence with those standards, making Bluetooth even more efficient and reliable.

A mesh network!

Bluetooth Mesh was released in mid-2017 and is a computer mesh networking standard based on Bluetooth Low Energy allowing many-to-many communication over Bluetooth radio.

Unlike the typical "star" topology where every node connects to a central network device forming a server-client relationship, the "mesh" topology eliminates the need of relying on one device for receiving the signal and gives to every node the opportunity to transfer the signal to the devices nearby.

In a mesh network, all nodes function as transmitters, relays, and receivers. This makes the size and area of the network virtually unlimited, and this is why it is so useful for industrial IoT operations like large connected sensor networks.

Bluetooth has evolved into a powerful wireless standard and will continue to become more important since the addition of mesh networks makes it a strong candidate for the future of industrial and domestic IoT connectivity.

Nikos Eleftherakis, Network Support Agent, Tardis4G | www.tardis4g.uk

A bit about the author:

Nikos is a Network Support Agent of Tardis, UK’s leading provider of construction site broadband solutions. Being a graduate of the Aristotle University of Thessaloniki and having experience working for a major Telecom company, Nikos is following his strong passion about technology and is taking every effort to develop his skills, while wanting to contribute to a better, more sustainable future.