802.11ax Multinode System-Level Simulation of Residential Scenario

Residential Scenario

This example demonstrates a system-level simulation to evaluate the performance of an 802.11ax network in a residential scenario. The residential scenario consists of a building with three floors. These are the characteristics of the residential scenario:

The simulation scenario specifies a path loss model based on the distance between the nodes, and the number of walls and floors traversed by the WLAN signal. This figure shows the residential scenario simulated in this example.

To confirm compliance with the IEEE 802.11 standard [2], the features in this example are validated with Box-3 and Box-5 scenarios specified in the TGax evaluation methodology [4]. The network throughputs that are calculated for TGax simulation scenarios [5] are validated against the published calibration results from the TGax Task Group.

Check for Support Package Installation

Check if the Communications Toolbox™ Wireless Network Simulation Library support package is installed. If the support package is not installed, MATLAB® returns an error with a link to download and install the support package.

wirelessnetworkSupportPackageCheck

Configuration Parameters

Simulation Parameters

Set the seed for the random number generator to 1. The seed value controls the pattern of random number generation. The random number generated by the seed value impacts several processes within the simulation, including backoff counter selection at the MAC layer and predicting packet reception success at the PHY layer. To improve the accuracy of your simulation results after running the simulation, you can change the seed value, run the simulation again, and average the results over multiple simulations.

rng(1,"combRecursive")

Specify the simulation time in seconds. To visualize a live state transition plot for all of the nodes, set the enablePacketVisualization variable to true. To view the node performance visualization, set the enableNodePerformancePlot variable to true.

simulationTime = 0.12;
enablePacketVisualization = true;
enableNodePerformancePlot = true;

This example uses the abstract models of MAC and PHY layers at all the nodes (APs and STAs) by default. To use the full MAC layer model, set the macabstraction variable to false. Similarly, to use the full PHY layer model, set the phyabstraction variable to none. For more information about MAC and PHY, see the Get Started with WLAN System-Level Simulation in MATLAB example.

macabstraction = true;
phyabstraction = "tgax-evaluation-methodology";

Residential Scenario Parameters

The ScenarioParameters structure defines the size and layout of the residential building by using these parameters.

The example assumes each room contains one transmitting AP and two receiving STAs.

ScenarioParameters = struct;
ScenarioParameters.BuildingLayout = [2 2 3];
ScenarioParameters.RoomSize = [10 10 3];
ScenarioParameters.NumRxPerRoom = 2;

Configure WLAN Scenario

Initialize the wireless network simulator by using the wirelessNetworkSimulator object.

networkSimulator = wirelessNetworkSimulator.init;

Nodes

The example creates a residential scenario consisting of 36 nodes. Node 1 to Node 12 are APs, and Node 13 to Node 36 are STAs. The hGetIDsAndPositions helper function returns node IDs and random positions for the AP and STAs within each room. The function returns an array, nodeIDs, where each row stores the IDs of the AP and its associated STAs in the same room. The apPositions and staPositions outputs contain the x-, y-, and z-Cartesian coordinates of the APs and STAs, respectively. Units are in meters.

[nodeIDs,apPositions,staPositions] = hGetIDsAndPositions(ScenarioParameters);

The wlanDeviceConfig object enables you to set the configuration parameters for the APs and STAs. Create two wlanDeviceConfig objects to initialize the configuration parameters for the APs and the STAs. Specify the operating mode, modulation and coding scheme, and the transmission power (in dBm) for the APs and STAs.

accessPointCfg = wlanDeviceConfig(Mode="AP",MCS=2,TransmitPower=15);    % AP device configuration
stationCfg = wlanDeviceConfig(Mode="STA",MCS=2,TransmitPower=15);       % STA device configuration

Create two arrays of wlanNode objects, corresponding to the AP nodes and STA nodes, by specifying their Position properties as apPosition and staPosition, respectively. Each array contains a number of objects equal to the number of positions specified by the corresponding value. Specify the Name, DeviceConfig, PHYAbstractionMethod, and MACFrameAbstraction properties of wlanNode objects.

accessPoints = wlanNode(Position=apPositions, ...
    Name="AP"+(1:size(apPositions,1)), ...
    DeviceConfig=accessPointCfg, ...
    PHYAbstractionMethod=phyabstraction, ...
    MACFrameAbstraction=macabstraction);
stations = wlanNode(Position=staPositions, ...
    Name="STA"+(1:size(staPositions,1)), ...
    DeviceConfig=stationCfg, ...
    PHYAbstractionMethod=phyabstraction, ...
    MACFrameAbstraction=macabstraction);

Create a WLAN network consisting of APs and STAs.

nodes = [accessPoints stations];

To ensure all the nodes are configured properly, use the hCheckWLANNodesConfiguration helper function.

hCheckWLANNodesConfiguration(nodes)

Association and Application Traffic

Associate the STAs in each room to the corresponding AP by using the associateStations object function of the wlanNode object. Configure the APs with continuous application traffic to their associated STAs by using the FullBufferTraffic argument.

numAPs = prod(ScenarioParameters.BuildingLayout);                                         % One AP per room
for apID = 1:numAPs
    associateStations(nodes(apID),[nodes(nodeIDs(apID,2:end))],FullBufferTraffic="DL");
end

Create Network

Create transmitter and receiver sites from the node configurations by using the hCreateSitesFromNodes helper function. Create the building geometry from the residential scenario parameters by using the hTGaxResidentialTriangulation helper object. Visualize the residential building along with the transmitter and receiver sites by using the hVisualizeScenario helper function.

[txSites,rxSites] = hCreateSitesFromNodes(nodes);
triangulationObj = hTGaxResidentialTriangulation(ScenarioParameters);
hVisualizeScenario(triangulationObj,txSites,rxSites,apPositions)

Wireless Channel

This example uses the TGax residential propagation model to determine path loss between nodes. Path loss is a function of the number of walls, number of floors, and distance between nodes. Create a path loss model by using the hTGaxResidentialPathLoss helper function. Obtain the path loss function handle by using the hCreatePathlossTable helper function.

propModel = hTGaxResidentialPathLoss(Triangulation=triangulationObj,ShadowSigma=0,FacesPerWall=1);
[~,pathLossFcn] = hCreatePathlossTable(txSites,rxSites,propModel);

To add a channel object to the wireless network simulator, create a hSLSTGaxMultiFrequencySystemChannel helper object by using the path loss function handle. Add the residential path loss model to the network simulator by using the addChannelModel object function of the wirelessNetworkSimulator object.

channel = hSLSTGaxMultiFrequencySystemChannel(nodes,PathLossModel="custom",PathLossModelFcn=pathLossFcn);
addChannelModel(networkSimulator,channel.ChannelFcn)

Simulation and Results

Add the nodes to the wireless network simulator.

addNodes(networkSimulator,nodes)

To view the state transition plot, use the hPlotPacketTransitions helper object. To disable the packet communication over frequency subplot, set the FrequencyPlotFlag property of hPlotPacketTransitions helper object to false.

if enablePacketVisualization
    packetVisObj = hPlotPacketTransitions(nodes,simulationTime,FrequencyPlotFlag=false);
end

To view the node performance visualization, use the hPerformanceViewer helper object.

perfViewerObj = hPerformanceViewer(nodes,simulationTime);

Run the network simulation for the specified simulation time. The runtime visualization shows the time spent by the AP and the STA in Idle, Contention, Transmission, and Reception state.

run(networkSimulator,simulationTime);

The plotNetworkStats object function displays these simulation plots.

if enableNodePerformancePlot
    plotNetworkStats(perfViewerObj);
end

Retrieve the APP, MAC, and PHY statistics at each node by using the statistics object function of the wlanNode object.

stats = statistics(nodes);

Further Exploration

You can use this example to further explore these functionalities.

Configure IEEE 802.11be Compliant Frame Transmissions

To configure IEEE 802.11be [3] compliant frame transmissions, you can:

For more information on TransmissionFormat and MCS properties, see the wlanDeviceConfig object.

Export WLAN MAC Frames to PCAP or PCAPNG File

You can capture packets at both AP and STA nodes by using the hExportWLANPackets helper object. Specify the node objects at which you want to capture the packets. To capture packets at multiple nodes, specify the corresponding node objects as an array. You can export the packets captured at the AP and STA nodes to a PCAP or PCAPNG file. For more information about capturing packets, and exporting captured packets to a PCAP or PCAPNG file, see the Get Started with WLAN System-Level Simulation in MATLAB example.

Appendix

The example uses these helpers:

References