Simulate 802.11ax Network with Custom TGax Channel

This example shows you how to simulate an IEEE® 802.11ax™ network with a custom channel by using WLAN Toolbox™ and the Communications Toolbox™ Wireless Network Simulation Library.

Using this example, you can:

1. Create and configure an 802.11ax network consisting of an access point (AP) and a station (STA).

2. Create a custom channel, and plug it into the wireless network simulator.

3. Simulate the 802.11ax network, and retrieve the statistics of the AP node and the STA node.

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

Create a wireless network simulator.

networkSimulator = wirelessNetworkSimulator.init;

Create a wlanDeviceConfig object, specifying these parameters.

• Operating mode — "AP"

• Operating frequency band and channel number — [5, 36]

• Number of transmit antennas — 1

• Channel bandwidth — 20 MHz

apDeviceCfg = wlanDeviceConfig(Mode="AP",BandAndChannel=[5 36], ...
    NumTransmitAntennas=1,ChannelBandwidth=20e6);

Use this configuration to create an access point and specify its name, position, and physical (PHY) layer abstraction method.

apNode = wlanNode(Name="AP",DeviceConfig=apDeviceCfg,Position=[0 0 0], ...
    PHYAbstractionMethod="tgax-evaluation-methodology",MACFrameAbstraction=true);

Create a wlanDeviceConfig object, specifying these parameters.

• Operating mode — "STA"

• Operating frequency band and channel number — [5, 36]

• Number of transmit antennas — 1

• Channel bandwidth — 20 MHz

staDeviceCfg = wlanDeviceConfig(Mode="STA",BandAndChannel=[5 36], ...
    NumTransmitAntennas=1,ChannelBandwidth=20e6);

Use this configuration to create a station node, and specify its name, position, and PHY abstraction method.

staNode = wlanNode(Name="STA",DeviceConfig=staDeviceCfg,Position=[25 0 0], ...
    PHYAbstractionMethod="tgax-evaluation-methodology",MACFrameAbstraction=true);

Associate the STA node with the AP node, and configure the downlink full uffer traffic using the associateStations function.

associateStations(apNode,staNode,FullBufferTraffic="DL");

Add the AP node and STA node to the wireless network simulator.

nodes = [apNode,staNode];
addNodes(networkSimulator,nodes);

Model a static fading 802.11ax™ (TGax) channel by using a residential path loss model to simulate communication between stationary nodes. Ensure these specifications.

• Use an abstracted physical layer

• The channel remains constant, reflecting the fixed positions of the nodes.

• Implement channel reciprocity.

• Equip each node with a single antenna and set the bandwidth to 20 MHz.

Use a custom function with this syntax: rxData = customFcnName(rxInfo,txData). The rxInfo input (a structure) is the receiver node information, and the txData input (a structure) specifies the transmitted packets. The simulator automatically passes information about the receiver node and the packets transmitted by a transmitter node as inputs to the custom function. For more information about this, see the addChannelModel object function.

% Configure channel
chan = wlanTGaxChannel;
chan.ChannelBandwidth = "CBW20";
chan.SampleRate = 20e6;
chan.DelayProfile = "Model-B";
chan.LargeScaleFadingEffect = "none";       % Model pathloss externally
chan.TransmitReceiveDistance = 20;          % Distance in meters for non-line-of-sight operation
chan.EnvironmentalSpeed = 0;                % Stationary channel
chan.ChannelFiltering = false;
chan.NumSamples = 1;
chan.NumTransmitAntennas = 1;
chan.NumReceiveAntennas = 1;

function rxSig = fadingChannel(rxInfo,txSig,chan)
    % Apply residential distance-based path loss, as defined in IEEE 802.11-14/0980r16
    dist = norm(txSig.TransmitterPosition-rxInfo.Position);     % Distance between the nodes
    dist = max(dist,1);
    numFloor = 0;                                               % Number of floors penetrated
    numWall = 0;                                                % Number of walls penetrated
    dBP = 5;                                                    % Breakpoint distance
    pathLoss = 40.052 + 20*log10((txSig.CenterFrequency/1e9)/2.4) + 20*log10(min(dist,dBP)) + (dist>dBP) * 35*log10(dist/dBP) + 18.3*numFloor^((numFloor+2)/(numFloor+1)-0.46) + 5*numWall;

    % Obtain path gains
    pathGains = chan();

    % Initialize the received signal structure (rxSig) with the transmitted signal (txSig)
    rxSig = txSig;

    % Adjust the power of the received signal to account for path loss
    rxSig.Power = rxSig.Power-pathLoss;

    % Retrieve channel information
    chanInfo = info(chan);

    % Create a structure to hold relevant channel characteristics
    channelCharacteristics = struct;
    channelCharacteristics.PathGains = pathGains;
    channelCharacteristics.PathFilters = chanInfo.ChannelFilterCoefficients;
    channelCharacteristics.PathDelays = chanInfo.PathDelays;
    channelCharacteristics.SampleTimes = txSig.StartTime+chanInfo.PathDelays;
    rxSig.Metadata.Channel = channelCharacteristics;
end

addChannelModel(networkSimulator,@(rxInfo,rxSig)fadingChannel(rxInfo,rxSig,chan));

Specify the simulation time in seconds and run the simulation.

simulationTime = 0.5;
run(networkSimulator,simulationTime);

Obtain the statistics for the AP node and the STA node.

stats = statistics(nodes);

Determine the AP node throughput in Mbps.

apThroughput = (sum([stats(1).MAC.TransmittedPayloadBytes])*8*1e-6)/simulationTime

apThroughput = 6.6240