|Article by Edward Au|
|There are many different kind of definitions, meanings, and interpretations on Internet of Things (IoT), because they depend heavily on, for example, the particular use cases, services and applications, objectives and contexts of interest.
There is, however, a common agreement that IoT is comprised of many different kinds of interconnected devices and “things”, which may refer to any type of device. Among all the standards-based and proprietary-based technologies, Bluetooth is one of the most popular, thanks to the recent addition of mesh networking capabilities.
Bluetooth technology, which is started in 1994, is a radio technology that supports short distance device communication of often within 10 meters. It allows wireless information to be exchanged between a variety of devices, such as laptops, mobiles, wearable devices, and wireless headsets. Until the introduction of Bluetooth Mesh, the main focus of Bluetooth was to address the point-to-point connectivity with applications on audio streaming and data transfer.
Specifically, while the point-to-point topology available on Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) is optimized for audio streaming (e.g., wireless headsets, wireless speakers), the point-to-point topology available on Bluetooth Low Energy (BLE) is optimized for very low-power data transfer (e.g., fitness trackers, smart watches) .
On the other hand, the mesh topology on BLE is optimized for creating large-scale device networks, making it ideal for emerging markets in need of a reliable wireless solution to establish large-scale control, monitoring, and automation systems. The table below provides a top-level comparison of different Bluetooth radios for different applications with different topology.
Bluetooth Mesh can be considered as a managed flood network in which only mains-powered nodes serve as relays. Low-power nodes, on the other hand, are not responsible for message relay. It has the following multi-layer architecture.
From the system’s viewpoint, Bluetooth mesh consists of a source node, a destination node, and many relay nodes whose function is to relay a message originating from the source node to the destination node. Here, all the data are carried in a message that is up to 384 bytes long, though most messages are 11 bytes long.
Each message has a source address, a destination address, a “time to live” counter, and a sequence number. When a message is received and re-transmitted, the “time to live” counter will be decremented whose purpose is to prevent endless loops/relaying from happening. The purpose of the sequence number is to protect the network against replay attacks.
With the introduction of mesh capabilities for many-to-many device communications, it is expected that Bluetooth will further enhance the user experiences in smart home and automation systems. For details on the specifications defined for Bluetooth mesh, please refer to .