I have some ambiguity in understanding the transmit time for a downstream packet, the reception time of a packet on a receiver, and how propagation delays are configured and implemented in the EMANE framework. This discussion is for single platform emulation, so time synch between separate platforms is not an issue.
Per the documentation, a radio model can send a TimeStampControlMessage to specify the transmission time stamp used in the CommonPHYHeader. This time should be the start-of-transmission time for the message. Presumably the actual platform time of transmit is the time stamp value provided plus the offset value in microseconds for a frequency segment. Presumably if this optional message is not provided, the time of the actual transmission of host traffic and specified on the CommonPHYHeader used as the timestamp is the platform's current real time clock value? Now is this the time that the host packet is actually passed over the OTA network at the specified transmit time, presumably representing a future time relative to the platform's current time when the processDownstream method is invoked? If not, would it be possible for a receiver to receive a message prior to the specified transmit time? If the time of transmit is already past relative to the platform time, does the packet get transmitted anyway? If the receiver uses the platform time stamp upon reception, does this represent the transmit time in the transmit packet's CommonPHYHeader plus some configured propagation delay? The timing analysis shim embeds in a custom header the platform transmit time as the real time clock, then upon reception, uses the platforms real time clock to determine the reception time, and logs the packet delay. Relative to the timing analysis shim, it logs the results after the stop() method of the shim layer is invoked? How is this method invoked from say the command line. Typically, I shut down EMANE by destroying the LXC that contains it, which does not appear to call stop(). What is the purpose of the timing analysis relative to this conversation and packet propagation delays? It appears to log the actual delay time between transmit and reception of a message relative to the platforms time standard (and not the time value in the CommonPHYHeader).
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