Introduction
In 1999 the Bluetooth® standard was released by Bluetooth® Special Interest Group (SIG), the non-profit organization behind the ubiquitous wireless standard used everyday in billions of devices.
In 2010 Bluetooth® Low Energy was released as a separate protocol from Bluetooth® (also known as Bluetooth® Classic). It was intended to provide considerable reduced power consumption and cost. It has been widely adopted for various applications, including wearables, sensors, and beacons powered by small coin cells.
Bluetooth® Low Energy and Bluetooth® Classic are used for very different purposes. Bluetooth® Classic is used in most computer and mobile phones, can handle a lot of data such as during audio streaming, but consumes battery life quickly and costs a lot more than Bluetooth® Low Energy. Bluetooth® Low Energy is used for applications that do not need to exchange large amounts of data and can therefore run on battery power for years at a cheap cost for applications such as access control and healthcare.
In 2017 Bluetooth® Mesh was released to address certain limitations of Bluetooth® Classic and Bluetooth® Low Energy. While Bluetooth® Classic and Bluetooth® Low Energy use a master/slave model of control, Bluetooth® Mesh allows for a distributed network of many-to-many. Bluetooth® Mesh was designed from the beginning to meet the strict requirements of commercial and industrial applications where performance, reliability and security are of the utmost importance.
In 2023 Bluetooth® NLC (Networked Lighting Control) was released to further improve interoperability. Standard Device Profiles define which options and features of Bluetooth® Mesh are mandatory for a certain kind of end product. Bluetooth® NLC introduces a standard at the device layer which enables true multi-vendor interoperability.
Bluetooth® Classic, Bluetooth® Low Energy, Mesh/NLC are very different standards intended for very different applications.
The use case of Lighting Controls
Bluetooth® Low Energy
Bluetooth® Low Energy is a low-power wireless communication technology designed for short-range communication. It is optimal for one-to-one connections but its capability starts to dwindle once many devices are required for the applications. Bluetooth® SIG does not have a standard specification for how Bluetooth® Low Energy communication should be implemented at scale.
Limitations:
- Limited scalability and network size: Bluetooth® Low Energy requires that all nodes maintain a one-to-one connection with other devices. This is extremely hard to maintain past 20 nodes as distances become greater than the area covered by a single Bluetooth® Low Energy device.
- Single points of failure: If a single Bluetooth® Low Energy node fails then any node it was responsible for helping receive messages will also fail.
- Limited resilience: There is no standard specification for a Bluetooth® Low Energy topology so it is up to each vendor to implement its reconfiguration techniques if a device fails.
- Security: Lacking a standard specification, security is optional and not mandated like in the case of Bluetooth® Mesh.
- Interoperability: There is no standard for creating IoT Bluetooth® Low Energy networks. This means all vendors implement proprietary protocols which will not communicate with Bluetooth® Low Energy devices created by other companies.
Bluetooth® Mesh
Bluetooth® Mesh is a networking technology that enables many-to-many communication among devices. It is designed to address the limitations of Bluetooth® Low Energy and provide enhanced security, resilience, redundancy, and robustness for wireless control systems. Unlike Bluetooth® Low Energy, Bluetooth® Mesh has requirements that have been defined and regulated by Bluetooth® SIG.
Advantages:
Scalability: Supports thousands of devices, enabling large-scale deployments. This is possible because Bluetooth® mesh uses beaconing which allows for much further transmission of data.
Resilience: Mesh topology ensures reliable message delivery through multiple pathways. This is possible because of managed flooding of the network where all devices are capable of receiving a message from any other node in the network. Self-healing capabilities allow the network to reconfigure itself in case of node or connection failures. If a node goes down no other node will be affected because the devices do not have any dependencies on each other. The next closest node will fill in forwarding messages to whoever needs them.
Redundancy: The mesh topology of Bluetooth® Mesh ensures that messages are delivered through multiple pathways, minimizing the chances of lost data or communication failures. In case of node or connection failures, the network can automatically reconfigure itself, maintaining its integrity and performance. This reconfiguration is possible because of requirements around TTL (Time To Live) and Transmits. The TTL of a message can be changed to allow it to travel further in a network increasing its chances of reaching the final destination. All devices also can change their Transmit states which will increase reliability by sending out multiple messages whenever a command is sent into the network.
Robustness: Bluetooth® Mesh offers extended range and better resistance to interference compared to Bluetooth® Low Energy, making it more suitable for large-scale deployments and harsh environments. This ensures reliable communication and control, even in challenging conditions. This is made possible because all nodes have multiple chances to receive the messages unlike a Bluetooth® Low Energy network where there is only one opportunity for a node to receive a message and if it misses it then the message will need to be sent again by the user. Bluetooth® Mesh avoids this by having multiple relay nodes in a network that each sends out the message a couple of times based on its transmit value.
Security: Strong encryption and authentication measures to protect data and prevent unauthorized access. Sequence numbers are used to protect against replay attacks and network keys are used to manage access. Bluetooth® Mesh incorporates advanced security measures, such as AES-CCM encryption and device authentication, to protect data and prevent unauthorized access. This helps alleviate concerns related to data breaches and unauthorized control of sensitive applications. Along with advanced encryption Bluetooth® mesh incorporates layers of security. This includes multiple different types of keys. Network keys are used to manage access based on location in the building. Application keys allow for compartmentalized control of different applications such as lighting, HVAC, and shades. The final key type is a device key which is required if changing any configuration on the device such as moving it from one room to another. Bluetooth® mesh is also resilient to Man-In-The-Middle attacks by mandating that every message be unique and unable to be replayed at a later time by a bad actor.
Bluetooth® NLC
Ensuring global interoperability requires standardization across all there layers of a wireless lighting control solution - the radio layer, communication layer, and the device layer Bluetooth® Network Lighting Control (NLC) defines functionality at the device layer which enables true multi-vendor interoperability and mass adoption of wireless lighting control.
Conclusion
Bluetooth® Mesh offers significant advantages over Bluetooth® Low Energy in terms of security, resilience, redundancy, and robustness, making it an ideal choice for wireless control systems. By adopting Bluetooth® Mesh, stakeholders can address the concerns and challenges faced with Bluetooth® Low Energy based solutions, ensuring reliable, secure, and efficient communication for their applications.
In addition, the recent release of Bluetooth® NLC guarantees interoperability at device level and compatibility amongst different vendors using the Bluetooth® NLC standard.