Create and Add Custom Traffic in 5G Network Simulation

Since R2026a

This example uses:

Traffic models define how data flows between nodes, providing a framework to simulate different types of network usage and application behaviors. With Wireless Network Toolbox™, you can create custom traffic models to meet your simulation needs. This example demonstrates how to create a traffic model from the wnet.Traffic base class and how to integrate it into your 5G simulation.

Implement Custom Traffic

To create a custom traffic model using the wnet.Traffic base class of Wireless Network Toolbox, follow these steps:

Inherit from the wnet.Traffic base class. The class definition must have this format, where customTraffic is the name of your custom traffic class.
Implement the base class public method generate. Also, implement any supporting methods and properties.

 classdef customTraffic < wnet.Traffic
    properties
        ...
    end

    methods
        function obj = customTraffic(varargin)
            % Constructor
            ...
        end

        function [dt,packetSize,packet] = generate(trafficObject,elapsedTime)
            ...
        end
    end

    % Supporting methods
    ...
end

Save the class definition in a .m file inside your directory.
In a simulation script, create an object of the customTraffic class. Plug this custom traffic object into nrUE and nrGNB nodes by using the addTrafficSource object function.

This example implements a periodic traffic model, hTrafficPeriodic, which generates packets of a specified size at a specified interval. The model is attached to this example as a supporting file. For more information on the implementation of the model, see Supporting File.

Simulate Network with Custom Traffic

Set the seed for the random number generator to 1 to ensure repeatability of results.

rng(1,"combRecursive");

Initialize the wireless network simulator.

networkSimulator = wirelessNetworkSimulator.init;

Create a 5G NR base station (gNB) node.

gnb = nrGNB(Name="nrgnb");

Create a user equipment (UE) node.

ue = nrUE(Name="nrue");

Establish a connection between the UE and gNB nodes.

connectUE(gnb,ue);

Create a periodic traffic pattern object using hTrafficPeriodic helper object. Specify the period (in seconds) and packet size (in bytes).

traffic = hTrafficPeriodic(Period=0.01,PacketSize=512);

Add the periodic traffic pattern to the gNB node and set the UE node as the destination for this traffic.

addTrafficSource(gnb,traffic,DestinationNode=ue);

Add the gNB and UE nodes to the wireless network simulator.

addNodes(networkSimulator,gnb);
addNodes(networkSimulator,ue);

If an event log file exists, delete it.

if exist("nreventLog.mat","file")
    delete("nreventLog.mat");
end

Create an event tracer object to log events to a MAT file during simulation runtime.

eventTracer = wirelessNetworkEventTracer(FileName="nreventLog.mat");

Add the gNB and UE nodes to the event tracer.

addNodes(eventTracer,gnb) % Logs the events "TransmissionStarted", "ReceptionEnded", "AppPacketGenerated", and "AppPacketReceived"
addNodes(eventTracer,ue)  % Logs the events "TransmissionStarted", "ReceptionEnded", "AppPacketGenerated", and "AppPacketReceived"

Run the simulation for 0.3 seconds.

run(networkSimulator,0.3);

Obtain and store performance statistics from the gNB node.

gnbStats = statistics(gnb);

Obtain and store performance statistics from the UE node.

ueStats = statistics(ue);

Read only the "AppPacketGenerated" events from node "nrgnb" from the event tracer.

events = read(eventTracer,EventName="AppPacketGenerated",NodeName="nrgnb");
disp(events);

  1×31 struct array with fields:

    EventName
    NodeName
    NodeID
    Timestamp
    TechnologyType
    EventData

Extract the timestamps for "AppPacketGenerated" events of the gNB node from the event log.

generationTimes = [events.Timestamp]

generationTimes = 1×31

         0    0.0100    0.0200    0.0300    0.0400    0.0500    0.0600    0.0700    0.0800    0.0900    0.1000    0.1100    0.1200    0.1300    0.1400    0.1500    0.1600    0.1700    0.1800    0.1900    0.2000    0.2100    0.2200    0.2300    0.2400    0.2500    0.2600    0.2700    0.2800    0.2900    0.3000

This verifies that the output is periodic, with each event occurring every 0.01 seconds.

Supporting File:

hTrafficPeriodic — Implements a periodic traffic model

classdef hTrafficPeriodic < wnet.Traffic
    
    properties
        % Period between generated packets, in seconds (must be a positive numeric scalar)
        Period (1,1) {mustBeNumeric,mustBePositive} = 1

        % Packet size in bytes (must be a positive integer scalar)
        PacketSize (1,1) {mustBeNumeric,mustBeInteger,mustBePositive} = 1500

        % Application data to be included in each packet (It must be column vector of integers between 0 and 255)
        ApplicationData (:,1) {mustBeNumeric,mustBeInteger,mustBeInRange(ApplicationData,0,255)} = ones(1500,1)
    end

    properties (Access = private)
        % Actual packet data after adjusting for packet size (column vector)
        pAppData

        % Timer (in ms) until the generation of the next packet
        pNextInvokeTime = 0
    end

    methods
        function trafficPeriodic = hTrafficPeriodic(varargin)
            % hTrafficPeriodic Constructor for the periodic traffic class

            % To enable support for configurable properties through name-value arguments, 
            % call the constructor of base class by using the name-value arguments as variable inputs
            trafficPeriodic@wnet.Traffic(varargin{:});

            % Initialize the packet data (pAppData)
            updatePacketData(trafficPeriodic);
        end

        function set.PacketSize(trafficPeriodic,value)
            % Set method for PacketSize property
            trafficPeriodic.PacketSize = value;
            updatePacketData(trafficPeriodic);
        end

        function set.ApplicationData(trafficPeriodic,value)
            % Set method for ApplicationData property
            trafficPeriodic.ApplicationData = value;
            updatePacketData(trafficPeriodic);
        end

        function [dt,packetSize,packet] = generate(trafficPeriodic,elapsedTime)
            % generate Generate the next packet after the specified period has elapsed

            %   [dt,packetSize,packet] = generate(trafficPeriodic,elapsedTime)
            %   - elapsedTime: (optional) time in ms since last call (default: 0)
            %   - dt: time in ms to next packet generation
            %   - packetSize: size of the packet generated in bytes (0 if no packet)
            %   - packet: application data (empty if no packet)
            %
            % This method maintains a countdown timer. When the timer reaches
            % zero, a packet is generated and the timer is reset to the period.

            arguments
                trafficPeriodic
                elapsedTime (1,1) {mustBeNonnegative} = 0  % Time in ms since last call (default: 0)
            end

            if nargin == 1
                % If no elapsedTime is provided, assume this is the first call
                % and reset the timer so a packet is generated immediately.
                trafficPeriodic.pNextInvokeTime = 0;
            else
                % Subtract elapsed time from the internal timer
                trafficPeriodic.pNextInvokeTime = trafficPeriodic.pNextInvokeTime - elapsedTime;
                % Round to avoid numerical errors
                trafficPeriodic.pNextInvokeTime = round(trafficPeriodic.pNextInvokeTime*1e6)/1e6;
            end

            if trafficPeriodic.pNextInvokeTime <= 0
                % Countdown timer has elapsed, so generate the next packet
                dt = trafficPeriodic.Period * 1000;      % Set next packet generation time (in ms)
                packetSize = trafficPeriodic.PacketSize; % Output the configured packet size
                trafficPeriodic.pNextInvokeTime = dt;    % Reset the countdown timer
                if nargout == 3
                    % Return the generated packet if requested
                    packet = trafficPeriodic.pAppData;
                end
            else
                % Packet generation is pending until the countdown timer expires
                dt = trafficPeriodic.pNextInvokeTime; % Time left until next packet (ms)
                packetSize = 0;           % No packet, so size is zero
                if nargout == 3
                    packet = [];          % No packet to return
                end
            end
        end
    end

    methods (Access = private)
        function updatePacketData(trafficPeriodic)
            % updatePacketData Update the size and content of application packet based on PacketSize and ApplicationData properties.
            n = trafficPeriodic.PacketSize;
            data = trafficPeriodic.ApplicationData;
            trafficPeriodic.pAppData = ones(n,1,"like",data); % Pre-fill with ones (default)
            m = min(n,numel(data));
            trafficPeriodic.pAppData(1:m) = data(1:m);        % Copy as much as fits
        end
    end
end

Create and Add Custom Traffic in 5G Network Simulation

Implement Custom Traffic

Simulate Network with Custom Traffic

Supporting File:

See Also

Objects

Classes