Energy Profiling of Bluetooth Mesh Nodes in Wireless Sensor Networks
This example shows how to perform energy profiling of nodes in a Bluetooth® mesh network by using Bluetooth® Toolbox. Using this example, you can:
Create and configure a Bluetooth mesh network.
Compute energy consumption of mesh nodes in transmission, listen, sleep, and idle states by varying the number of Relay nodes, source-destination node pairs, Friend node-Low Power node (LPN) pair, and the application traffic.
Estimate the lifetime of mesh node based on the configured hardware-specific energy parameters.
Explore the impact of poll timeout and receive window size on the LPN lifetime.
The results confirm the expectation that LPN always consume less energy by spending more time in sleep, resulting in energy conservation and increased lifetime.
Bluetooth Mesh Energy Profiling
The Bluetooth mesh profile [ 3 ] defines the fundamental requirements to implement a mesh networking solution for Bluetooth LE. Bluetooth mesh networking enables large-scale device networks in the applications such as smart lighting, industrial automation, sensor networking, and asset tracking. For information about Bluetooth LE protocol stack, see Bluetooth Protocol Stack.
Each Bluetooth mesh node possess some optional features enabling them to acquire additional capabilities. These features include the Relay, Proxy, Friend, and the LowPower features. The Bluetooth mesh nodes possessing these features are known as Relay nodes, Proxy nodes, Friend nodes, and LPNs, respectively. To reduce the duty cycles of the LPN and conserve energy, the LPN must establish a Friendship with a Friend node (mesh nodes supporting the Friend feature). For more information about devices, nodes, and the Friendship in Bluetooth mesh network, see Bluetooth Mesh Networking.
In this example, the source nodes initiates mesh communication to a destination node and an LPN. During the simulation, the Friend node and LPN exchange Friendship messages. Each node computes the time spent in various states (transmission, listen, idle and sleep) and calculates its lifetime.
Configure Simulation Parameters
Set the seed for the random number generator to 1. The seed value controls the pattern of random number generation. For high fidelity simulation results, change the seed value for each run and average the results over multiple simulations.
Specify the simulation time.
simulationTime = 5; % In seconds
Specify total number of nodes in the mesh network.
numNodes = 21;
Get the node positions from the MAT file. Specify the positions of Bluetooth mesh nodes as a
numNodes-by-2 array, where
numNodes is the number of nodes in the network. Each row specifies the Cartesian coordinates of a node, starting from the first node.
load("bleMeshNetworkNodePositions.mat"); if numNodes ~= size(bleMeshNetworkNodePositions,1) error("Invalid Bluetooth mesh node position value. Specify 'bleMeshNetworkNodePositions' value in the MAT file as a "... +num2str(numNodes)+"-by-2 array."); end
Set some of the nodes as relay nodes, source-destination node pairs, friend node and LPN.
relayNodes = [3 6 7 8 9 12 13 14 17]; sourceDestinationPairs = [1 20; 21 16]; friend = 15; lpn = 16;
networkSimulator = wirelessNetworkSimulator.init();
Create and Configure Bluetooth Mesh Nodes
Initialize array to store Bluetooth mesh nodes.
meshNodes = bluetoothLENode.empty(0,numNodes);
Create Bluetooth mesh network. Use
bluetoothMeshProfileConfig to create mesh profile configuration object. To create a Bluetooth mesh node, use the
bluetoothLENode object. Specify the role as "
broadcaster-observer" and assign the mesh profile to
for nodeIndex = 1:numNodes % Create and configure Bluetooth mesh profile by specifying the element % address (unique to each node in the network). Set relay and network % message repetitions. meshCfg = bluetoothMeshProfileConfig(ElementAddress=dec2hex(nodeIndex,4),... NetworkTransmissions=3,RelayRetransmissions=3); % Enable Relay feature of the configured relay nodes if any(nodeIndex==relayNodes) meshCfg.Relay = true; elseif nodeIndex==friend % Enable Friend feature of the configured Friend nodes meshCfg.Friend = true; elseif nodeIndex==lpn % Enable LowPower feature of the configured Low Power nodes meshCfg.LowPower = true; end % Create and configure Bluetooth mesh node by assigning the mesh profile. % Set receiver range, advertising interval (seconds) and scan interval (seconds). meshNodes(nodeIndex) = bluetoothLENode("broadcaster-observer",MeshConfig=meshCfg, ... Position=[bleMeshNetworkNodePositions(nodeIndex,:) 0],Name="Node"+num2str(nodeIndex),... ReceiverRange=25,AdvertisingInterval=20e-3,ScanInterval=30e-3); end
Configure Friendship Between Friend Node and LPN
Set friendship timing parameters (in seconds) such as poll timeout, receive window, and receive delay by using the
friendshipConfig = bluetoothMeshFriendshipConfig(PollTimeout=2,ReceiveWindow=180e-3,... ReceiveDelay=50e-3);
Add Application Traffic to Source Nodes
networkTrafficOnOff object to generate an On-Off application traffic pattern. Configure the On-Off application traffic pattern by specifying the application data rate, packet size, on, and off state duration. Use
addTrafficSource object function to attach the application traffic source between the specified source-destination node pairs.
for srcIdx = 1:numel(sourceDestinationPairs)/2 % Set data rate, packet size, on time, and off time based on the % simulation time traffic = networkTrafficOnOff(DataRate=1,PacketSize=15,GeneratePacket=true,... OnTime=simulationTime*0.3,OffTime=simulationTime*0.7); % Maximum number of hops for a packet is controlled by setting % time-to-live (TTL) value ttl = 10; % Attach application traffic to source addTrafficSource(meshNodes(sourceDestinationPairs(srcIdx,1)),traffic,... % Traffic object SourceAddress=meshNodes(sourceDestinationPairs(srcIdx,1)).MeshConfig.ElementAddress,... % Source element address DestinationAddress=meshNodes(sourceDestinationPairs(srcIdx,2)).MeshConfig.ElementAddress,... % Destination element address TTL=ttl); end
Visualize Mesh Network
Visualize the mesh network scenario by using the helperBLEMeshVisualizeNetwork helper object.
plotNetwork = helperBLEMeshVisualizeNetwork(NumberOfNodes=numNodes,... NodePositionType="UserInput",Positions=bleMeshNetworkNodePositions,... ReceiverRange=25,SimulationTime=simulationTime,... SourceDestinationPairs=sourceDestinationPairs,FriendPairs=[friend lpn],... Title="Energy Profiling in Bluetooth Mesh Network");
Assign the helper object to the
NetworkPlot parameter in the helperBLEMeshEventCallback helper object. For information about how to visualize the message flow in the mesh network, see Bluetooth Mesh Flooding in Wireless Sensor Networks.
networkEvents = helperBLEMeshEventCallback(meshNodes,plotNetwork);
Run the simulation
Add nodes to the wireless network simulator.
Run the network simulation for the specified simulation time.
Custom channel model is not added. Using free space path loss (fspl) model as the default channel model.
At each mesh node, the simulation captures these statistics.
Application end-to-end packet latency in seconds
Link layer (LL) throughput in Kbps
Time spent in listen state, transmit state, idle state and sleep state in seconds
Packet statistics at the application layer, network layer, transport layer, LL and physical layer
The workspace variable
statisticsAtEachNode contains the cumulative value of the preceding statistics for all the nodes in the network. Use
statistics object function to get the statistics of mesh nodes in the network.
% List of statistics (structure array) of the simulated mesh nodes in the network for nodeIndex = 1:numNodes statisticsAtEachNode(nodeIndex) = statistics(meshNodes(nodeIndex)); %#ok<*SAGROW> end
This plot shows the average time spent by different type of mesh nodes in different states. The results conclude that the LPN spend most of the time in sleep state, resulting in energy conservation and increased lifetime.
fprintf("Average time statistics of different Bluetooth mesh nodes are:\n");
Average time statistics of different Bluetooth mesh nodes are:
meshNodesAvgStats = helperBLEMeshNodeAverageTime(meshNodes);
Configure the traffic between the mesh nodes by using the
addTrafficSource object function of the
bluetoothLENode object. The transmission time at the mesh node depends on the application traffic. The transmission time at the LPN depends on the poll timeout value.
Calculate Lifetime of LPN:
At the end of the simulation, calculate the lifetime of a node in the Bluetooth mesh network by using the helperBLEMeshNodeLifetime helper function. To compute node lifetime, the simulation time and the mesh node is given as an input to the helperBLEMeshNodeLifetime helper function. The node lifetime is calculated by using the energy parameters that are hardware dependent. To update these hardware parameters, use the helperBLEMeshNodeLifetime helper function.
lifeTime = helperBLEMeshNodeLifetime(meshNodes(lpn),simulationTime);
Configured hardware parameters for a 1200 mAh battery are: Hardware parameters Configured values (mA) __________________________ ______________________ Self-discharge 0.0013699 Transmission on channel 37 7.57 Transmission on channel 38 7.77 Transmission on channel 39 7.7 Listening 10.3 Sleep 0.2 Idle 1.19 Timing metrics at Node16 are: Time variables Time (seconds) _________________ ______________ Transmission time 0.016704 Listen time 1.2 Sleep time 2.9018 Idle time 0.5803
fprintf("Lifetime of %s is %.4f days.\n",meshNodes(lpn).Name,lifeTime);
Lifetime of Node16 is 18.1606 days.
Lifetime of LPN by Varying Poll Timeout
The lifetime of an LPN depends on the time for which the node is in the listen state. In a given poll timeout, an LPN is in listen or sleep state for most of the time. The receive window for each poll request of an LPN determines the time spent in listen state. The time spent in transmission state is negligible.
Visualize the impact of the poll timeout and receive window on the lifetime of LPN by using the helperBLEMeshLPNLifetimeVSPolltimeout helper function.
The preceding plot concludes that the lifetime of LPN is directly proportional to the poll timeout. The poll timeout specifies the maximum time between two consecutive requests from an LPN to Friend node. As the poll timeout increases, the LPN spends more time in sleep state that results in increasing the lifetime of the LPN.
The example uses these helpers:
helperBLEMeshEventCallback: Callback function to visualize message transmissions
helperBLEMeshVisualizeNetwork: Bluetooth mesh network visualization
helperBLEMeshNodeLifetime: Compute lifetime of a Bluetooth mesh node
helperBLEMeshNodeAverageTime: Compute average time spent in various states by the Bluetooth mesh nodes
helperBLEMeshLPNLifetimeVSPolltimeout: Compute the lifetime of Bluetooth mesh LPN for different poll timeout and receive window values
Bluetooth Technology Website. “Bluetooth Technology Website | The Official Website of Bluetooth Technology.” Accessed May 24, 2022. https://www.bluetooth.com.
Bluetooth Special Interest Group (SIG). "Bluetooth Core Specification". Version 5.3. https://www.bluetooth.com/.
Bluetooth Special Interest Group (SIG). "Bluetooth Mesh Profile". Version 1.0.1. https://www.bluetooth.com/.