See Setup for setup.

NOTE: This is a preliminary DRAFT. Graphs look wrong. Math needs evaluated. 802.11 MAC traffic needs evaluated.

Sensor QoS

This example models one robot talking to four robots using Sensor QoS, as follows:

The scenario setup file for this example defines 10-byte messages at 2 Hz using QoS history=keep_last, depth=5, reliability=best_effort, and durability=volatile. It is at https://github.com/nps-ros2/ns3_testbed/blob/master/csv_setup/example_keep_last_5.csv and is shown here:

Publish,,,,,,,
Node,Subscription,Frequency,Size,History,Depth,Reliability,Durability
R1,odometry,2,10,keep_last,5,best_effort,volatile
,,,,,,,
Subscribe,,,,,,,
Node,Subscription,History,Depth,Reliability,Durability,,
R2-5,odometry,keep_last,5,best_effort,volatile,,

The ns-3 setup file for this example is at https://github.com/nps-ros2/ns3_testbed/blob/master/csv_setup/ns3_25_7.csv and is shown here:

mobility,,,
Node,X,Y,Walks
R1,0,0,false
R2,25.7,0,false
R3,0,25.7,false
R4,-25.7,0,false
R5,0,-25.7,false

Run

• Start the Testbed Monitor, specifying to write output to file sensor.csv:

  cd ~/gits/ns3_testbed/testbed_monitor
  ./testbed_monitor.py -o sensor.csv
  

• Start the ns-3 simulator program, providing setup file ns3_25_7.csv:

  cd ~/gits/ns3_testbed/ns3_programs/build
  ./ns3_mobility -s ns3_25_7.csv
  

• Start the robots, providing setup file example_keep_last_5.csv:

  sudo /bin/bash
  cd ~/gits/ns3_testbed/cpp_testbed_runner/build/cpp_testbed_runner
  ./testbed_runner -c 5 -i example_keep_last_5.csv -n -p
  

• Allow the simulation to run for a few minutes, then stop the started programs.

Analysis

When we ran the testbed monitor, it created output in CSV file sensor.csv. We post-processed this output using the plot_analytics.py program, specifying the output name, plot title text, maximum latency, and the root name of the output file to write to:

  cd ~/gits/ns3_testbed/testbed_monitor
  ./plot_analytics.py sensor.csv "keep last 5, best_effort, volatile", -m 100 -w sensor

Here are the results:

Latency point plot:

Latency:

Loss:

Throughput:

3V3

3v3 consists of 7 robots: two teams, three drones each, 1 ground station. Mobility is random walk, in range, and QoS is the ROS2 Sensor QoS model.

Configuration

Scenario setup in example_3v3.csv:

Publish,,,,,,,
Node,Subscription,Frequency,Size,History,Depth,Reliability,Durability
R1,heartbeat,1,20,keep_last,0,best_effort,volatile
R2-7,flight status,2,48,keep_lst,0,best_effort,volatile
R2-7,pose,10,56,keep_last,0,best_effort,volatile
R1,red pose,10,40,keep_last,0,best_effort,volatile
,,,,,,, and QoS is random walk drones, in range, Sensor QoS.
Subscribe,,,,,,,
Node,Subscription,History,Depth,Reliability,Durability,,
R2-7,heartbeat,keep_last,0,best_effort,volatile
R1,flight status,keep_last,0,best_effort,volatile
R1,pose,keep_last,0,best_effort,volatile
R2-7,red pose,keep_last,0,best_effort,volatile

ns-3 setup in ns3_1_gs.csv:

mobility,,,
Node,X,Y,Walks
R1,0,0,false
R2-99,0,0,true

Run

Testbed monitor, output to 3v3.csv:

cd ~/gits/ns3_testbed/testbed_monitor
./testbed_monitor.py -o 3v3.csv

ns-3 simulator for 1 GS and random-walk nodes:

cd ~/gits/ns3_testbed/ns3_programs/build
./ns3_mobility -c 7 -l 10 -s ns3_1_gs.csv

Robots running the 3v3 scenario:

sudo /bin/bash
cd ~/gits/ns3_testbed/cpp_testbed_runner/build/cpp_testbed_runner
./testbed_runner -c 7 -i example_3v3.csv -n -p

Allow the simulation to run for a while.

Analysis

Create plots:

cd ~/gits/ns3_testbed/testbed_monitor
./plot_analytics.py 3v3.csv "3v3" -m 175 -w 3v3

Latency point plot:

Latency:

Loss:

Throughput:

6v6

Run

Testbed monitor, output to 6v6.csv:

cd ~/gits/ns3_testbed/testbed_monitor
./testbed_monitor.py -o 6v6.csv

ns-3 simulator for 1 GS and random-walk nodes:

cd ~/gits/ns3_testbed/ns3_programs/build
./ns3_mobility -c 13 -l 10 -s ns3_1_gs.csv

Robots running the 6v6 scenario:

sudo /bin/bash
cd ~/gits/ns3_testbed/cpp_testbed_runner/build/cpp_testbed_runner
./testbed_runner -c 13 -i example_6v6.csv -n -p -s

Allow the simulation to run for a while.

Analysis

Create plots:

cd ~/gits/ns3_testbed/testbed_monitor
./plot_analytics.py 6v6.csv "6v6" -m 30 -w 6v6

Note that robots are started at staggered intervals. Otherwise, it takes several minutes for traffic to stabilize.

Latency point plot:

Latency:

Loss:

Throughput: