Bluetooth Mesh is a veritable innovation of BLE, competing with mesh-capable Zigbee and Thread technologies. This is essentially made possible by interconnected nodes. These nodes act as points in a decentralized network, sharing data and extending the network’s reach and capabilities. In the early days of Bluetooth Mesh, there were anticipations about how big this new mesh technology would be adopted – projections made just since BLE mesh was launched in 2017. Many talked about ” BLE mesh networks” becoming a reality within a few years. Despite its potential, it hasn’t experienced the explosive growth seen in other BLE technologies.
What is Bluetooth mesh technology
Bluetooth Mesh is Bluetooth combined with mesh networking.
Mesh network, also known as “multi-hop network”, is a networking topology. In a mesh network, data can travel from any device to all others, achieving many-to-many communication. Even if one device fails, the network keeps working.
Bluetooth Mesh uses Bluetooth Low Energy, which came with Bluetooth 4.0. In 2017, the official Bluetooth Mesh 1.0 was released (still the latest up to now). It should be clear that BLE mesh is not a new wireless communication technology, but a networking technology. It utilizes and relies on BLE, and uses its communication protocol stack.
Bluetooth mesh networks use managed flooding. Devices can talk one-to-one, one-to-many, or many-to-many. By using the BLE protocol for communication between different network nodes, it forms a network without communication dead zones. All enable messages to travel further than traditional Bluetooth.
How does Bluetooth mesh work
Unlike traditional one-to-one connections, Bluetooth mesh creates a network where messages can hop from device to device until reaching their destination. One or more routes may exist between two device nodes. BLE mesh works by broadcasting messages to all nearby nodes, which then relay them onward. This process continues until the message reaches its intended destination(s).
This “managed flooding” ensures messages reach their targets even if some devices are out of direct range or turned off. Devices can publish messages to specific addresses, and others can subscribe to receive them. This publish-subscribe pattern enables efficient group communication.
The basics of Bluetooth mesh networking
After understanding how Bluetooth mesh works, it’s important to grasp some key technical terms and concepts of this technology. Let’s break down some of them:
- Nodes: When a Bluetooth device joins a Bluetooth Mesh network, it becomes a “node.” The node is a participant in the BLE mesh network.
- Elements: Each node is composed of one or more “elements.” An element is like a functional unit within the node. Every node has at least one element, but it can have multiple elements if it performs various functions.
- Models: Elements contain “models,” which define specific behaviors or services of the node. Models have unique ID numbers and determine what a node can do. There are standard models defined by the Bluetooth SIG that cover many common scenarios.
- Message: When messages are sent between nodes, they’re filtered based on matching elements and models.
- Addresses: Addresses are used to identify the source and destination of messages.
Types of nodes:
In a Bluetooth mesh network, there are several types of nodes, each with specific roles:
- Relay Nodes: Messages are sent to nodes in direct radio range of the publishing node. There are some nodes function as “relays”. Relays retransmit messages so they can travel further, in a number of “hops”.
- Friend Nodes and Low Power Nodes: LPNs are highly power-constrained. To avoid maintaining a higher duty cycle for receiving messages, an LPN partners with a Friend. Friend nodes store messages for their LPNs and forward them when the LPN polls occasionally.
- Proxy Nodes: Bluetooth low energy devices, such as smartphones, can connect to a mesh network through a proxy node.
To know more fundamental concepts, you can refer to the Bluetooth mesh glossary.
The BLE mesh system architecture
The BLE Mesh protocol architecture consists of seven layers, built upon the BLE core specification with which you are already familiar. However, it adds sophisticated upper-layer functionality to create a network of interconnected devices. BLE mesh relies on the availability of the BLE protocol stack.
From bottom to top, the layers are as follows:
- Bearer Layer
- Network Layer
- Lower Transport Layer
- Upper Transport Layer
- Access Layer
- Model Layer
- Application Layer
The Bearer Layer defines how messages are sent and received using the underlying BLE protocol stack. It supports two methods: Advertising Bearer (PB-ADV) and GATT Bearer (PB-GATT). Several intermediate layers handle critical tasks. These include encrypting and decrypting data, managing network configuration, and message segmentation and reassembly, etc. These layers ensure that messages reach their intended destinations, even if they need to traverse multiple devices.
The Model Layer defines standardized typical user scenarios, such as controlling lighting or reading sensors. The Application Layer, positioned at the very top, organizes these models into useful applications with which end-users can interact.
Benefits and limitations of BLE mesh networking
BLE mesh satisfies the demands of smart connectivity – large-scale, low-power, flexible, and secure. However, it is not a one-size-fits-all solution and, like any technology, has its strengths and weaknesses.
Advantages of BLE mesh networking
- Low Power Consumption: BLE mesh, like other BLE systems, features low power consumption. Therefore, a mesh network works well when covering large areas while conserving energy.
- Network Resilience: In a Bluetooth mesh network, device nodes can disconnect without major impact. If one device drops out, the initial node will keep broadcasting the data. The addressee will receive the packet with a brief delay.
- Flexibility and Self-Reconfiguration: The mesh network reconfigures itself. This flexibility is sometimes more important than guaranteed speed and shorter delays.
- Node Mobility: In a BLE mesh network, nodes can change their position without disrupting the structure or losing data in transit. Data will only fail to reach its destination if nodes move out of range of the receiver.
- Compatibility: BLE mesh nodes can communicate with both Bluetooth 4.x and 5.x devices. Bluetooth 4.x devices can receive messages but can’t become fully-fledged nodes of the network.
- Beacon Integration: BLE mesh works closely with Bluetooth beacons. Beacons can used in indoor outdoor positioning, sensor networks, and other applications.
Limitations of BLE mesh networking
- Low data throughput: Bluetooth mesh has limited data transfer rates. It’s limited to about 1 megabit per second, or even less. This means it’s not suitable for applciations that need faster data transfer.
- High latency: Bluetooth mesh uses “managed flooding”, so messages are sent to all devices in the network. It can take a long time for messages to reach everyone and get responses back. The more nodes, the longer response time it might take.
- Power consumption: While Bluetooth is often thought of as consuming less power than other technologies, this isn’t always true in a mesh network. In a mesh, there are lots of devices. The devices that take more task drain more battery power. This is because they have to always be listening for messages and sending them to other devices.
- Complex network management: Setting up and managing a Bluetooth mesh network is complicated and requires extensive specialized knowledge.
Bluetooth mesh vs other technologies
Apart from BLE mesh, other popular mesh networking technologies include Zigbee and Thread. These technologies share much similarities with BLE mesh networking.
Thread, introduced in 2014, is an IPv6-based mesh networking protocol for IoT. It supports up to 32 routers per network and 511 devices per router, suitable for high-density meshnets. As an IP-addressable solution, Thread integrates easily with IPv6-based apps and offers high data rates for local IoT systems.
Zigbee appeared much earlier in 1998 and then standardized in 2003. It is a low-power, low-bandwidth wireless network. Popular applications include home automation, medical devices, and industrial applications. It has a 250 Kbps maximum rate and supports various frequencies and power ranges. Zigbee often requires a gateway, so it is rarely built into consumer electronics integration.
Main differences between Thread, Zigbee, and Bluetooth mesh:
- Protocol Base: BLE mesh uses Bluetooth instead of the Internet Protocol, while Thread and Zigbee are IP-based.
- Frequency Bands: BLE mesh operates in the 2.4 GHz band. Zigbee can use 2.4 GHz, 915 MHz, or 868 MHz bands depending on the region. Thread also operates in the 2.4 GHz band.
- Messaging Approach: BLE mesh uses managed flood messaging, whereas Zigbee and Thread use routing mechanisms.
- RAM Usage: Zigbee and Thread devices require more RAM to store routing tables.
- Network Density: BLE mesh works better for low-density meshnets due to its flooding approach. Zigbee and Thread are more suitable for high-density networks.
- Maximum Device Support: Thread can support up to 511 devices per router, with a maximum of 32 routers per network. Zigbee can theoretically support up to 65,000 nodes in a single network. BLE mesh can support over 32,000 nodes.
Why use our Bluetooth mesh devices
Adopting new technology can be challenging. I hope that this Bluetooth mesh guide can give you some ideas. At MOKO SMART, we’re not just suppliers; we’re pioneers in Bluetooth technology. Our Bluetooth IoT devices range includes Bluetooth beacons, anchors, gateways, and sensors.
As an original IoT device manufacturer, we provide top-quality and reliable devices for all your Bluetooth mesh needs. If you are considering deploying a BLE mesh solution or seeking BLE mesh products, feel free to contact us.
FAQs about Bluetooth mesh
How many devices can a Bluetooth Mesh network support?
A single Bluetooth Mesh network can support up to 32,767 devices.
Can Bluetooth Mesh networks interact with non-mesh Bluetooth devices?
Yes, through proxy nodes, Bluetooth Mesh networks can interact with regular Bluetooth Low Energy devices.
