Test Specification TC21.TS1
Test Rationale
This test allows determining, as a first step, which is the minimum periodicity for which data sent from the real time simulator will result in a packet loss rate less than 1%. This information is needed for the design of the experiment needed to run TS02.
Specific Test System
The test system is comprised by the components and their interconnection according to the figure shown above.
The real time simulator must send a data profile composed of integer values using “protocol 1” and a value α less than 1.
Additionally, the real time simulator must internally register a timestamp for each value sent and a timestamp for when this value is received (if the value is not lost).
The communication emulator delay setting must be “0”. This will allow determining the minimum duration a value has to be sent for a 100% successful transmission rate.
Target measures
- The roundtrip time for each value sent from the real time simulator to reach the real time simulator, going through the communication devices and the communication emulator.
Input and output parameters
Controllable input parameters:
- Number of numbers that will be used for the data profile (e.g. 30).
- The proportion for which the next sending duration of the next value will be decreased (factor α).
- The specific communication protocol to send the information (Protocol 1 and 2).
- The number of times the data profile will be sent around the system to obtain statistically valid results (e.g. 1000 times) Uncontrollable parameters:
- Time that it takes the data to be received by the real time simulator Measured parameters:
- Values received by the real time simulator
- Roundtrip time of each value received by the real time simulator.
Test Design
- Choose data profile to be sent around the system.
- Choose the number of times the data profile will be sent around the system.
- Choose communication protocols “Protocol 1” and “Protocol 2”
- Set the delay emulation from the communication emulator to “0”
- Run the experiment and determine for each sent value whether the real time simulator received it.
- If the value was received, determine the roundtrip time by calculating the difference of the timestamps registered by the real time simulator.
- Assess test criteria for each of the values.
Initial system state
- Devices are on and running
- The real time simulator has sent any value
- The registrations (in the real time simulator) of successful received values and the timestamps of sending/receiving values are empty
Evolution of system state and test signals
- The successful received values and the timestamps of sending/receiving values are registered in the real time simulator.
Other parameters
N/A
Temporal resolution
- Polling frequency parameters of the protocols being used should be less than the value that has the minimum transmission duration. Polling frequency in the range 1ms-10ms is recommended.
Source of uncertainty
The delay that can occur within any of the devices used in the system has a stochastic nature. These are therefore sources of uncertainty.
Suspension criteria / Stopping criteria
Suspension criteria: Errors in devices Stopping criteria: the experiment concludes when the data profile has been sent a previously defined number of times.