What Is Bluetooth Mesh?

Bluetooth^® mesh is a networking technology developed by the Bluetooth Special Interest Group that enables many-to-many communications between distant Bluetooth devices. Also known as Bluetooth mesh networking, it is implemented on top of the Bluetooth Low Energy (LE) variant of Bluetooth. The technology’s routing strategy, called managed flooding, makes routing very robust when individual network nodes fail.

System designers use Bluetooth mesh for applications such as building automation, sensor networks, industrial lighting, smart homes, remote monitoring, and other large-scale Internet of Things (IoT) applications. Designers use Bluetooth mesh because of the following capabilities:

• Low energy consumption
• Coverage area extension through multihop communication
• Excellent network scalability through efficient use of radio resources
• Communications security through authentication and encryption
• High system reliability through redundant message routes
• Low network latencies

Model Bluetooth Mesh in MATLAB

MathWorks Bluetooth^® Toolbox enables the creation of a Bluetooth mesh network with the Create, Configure, and Visualize Bluetooth Mesh Network example. Each network node models several of the Bluetooth mesh protocol layers, pictured in blue in Figure 1. In a physical Bluetooth mesh network, these layers define the following capabilities:

• Network provisioning
• Encryption, decryption, and message authentication to enhance security
• Message segmentation and reassembly
• Network configuration and management
• Management of use case scenarios (e.g., lighting control)

You can create a Bluetooth LE node with the MATLAB^® command bluetoothLENode. This node object performs both PHY and MAC operations, and acts as both a transmitter and receiver. Here is a sample output from a bluetoothLENode call that creates a broadcaster-observer node:

>> node = bluetoothLENode("broadcaster-observer")

node = 

  bluetoothLENode with properties:

        TransmitterPower: 20
         TransmitterGain: 0
           ReceiverRange: 100
            ReceiverGain: 0
     ReceiverSensitivity: -100
             NoiseFigure: 0
    InterferenceFidelity: 0
     AdvertisingInterval: 0.0200
       RandomAdvertising: 0
            ScanInterval: 0.0050
              MeshConfig: [1×1 bluetoothMeshProfileConfig]
                    Name: "Node1"
                Position: [0 0 0]

   Read-only properties:
                    Role: "broadcaster-observer"
        FriendshipConfig: [1×1 bluetoothMeshFriendshipConfig]
          TransmitBuffer: [1×1 struct]
                      ID: 1

Model Bluetooth Mesh Node Types

Devices in a Bluetooth mesh network, also called nodes, can serve different purposes and are given different names. Figure 2 shows the interactions between these different node types.

The nodes are described as follows.

• Relay nodes: Retransmit received messages through multiple hops
• Low-power node: Also known as LPNs, nodes that are power constrained can use the low-power feature to minimize the On time of the radio and conserve energy  
  
• Friend node: Nodes that do not have any power constraints acting to support LPNs (the relationship between an LPN and a Friend node is called Friendship)

You can use MATLAB^® to visualize the energy profile of Bluetooth mesh nodes in wireless sensor networks, with the Energy Profiling of Bluetooth Mesh Nodes in Wireless Sensor Networks example.

Model Managed Flooding in Bluetooth Mesh Networks

The Bluetooth Mesh Flooding in Wireless Sensor Networks example demonstrates managed flooding. This example enables you to specify node positions and types, to control the degree of flooding, to visualize the flow of packets from source to destination, and to calculate network throughput.

Many mesh networks implement routing mechanisms to optimize message relay. Other networks flood their nodes with relay messages without any consideration of optimal routes. Bluetooth mesh networking uses an approach called managed flooding that includes both these mechanisms. Figure 3 illustrates managed flooding in Bluetooth mesh.

Figure 3 illustrates communication between a switch and a connected light bulb in a Bluetooth mesh.  Initially, the switch and bulb are in the Off state. Changing the switch to the On state broadcasts a message to turn on the bulb. All the mesh nodes in range of the switch hear the message, but only the green relay nodes retransmit the message until it reaches the bulb.