The delay histogram in flow monitor

[yang li]

Hello, everyone

I am currently using flow monitor module to capture the traffic flows for my LTE model.

The thing is that I do not fully understand the part in delayhistogram since i need to take latency as one of my measurement.

The xml file generated by flow monitor has following sections in delay histogram:

 <delayHistogram nBins="79" >
        <bin index="14" start="0.014" width="0.001" count="3" />
        <bin index="15" start="0.015" width="0.001" count="874" />
        <bin index="16" start="0.016" width="0.001" count="823" />
        <bin index="17" start="0.017" width="0.001" count="744" />
        <bin index="18" start="0.018" width="0.001" count="698" />
        <bin index="19" start="0.019" width="0.001" count="323" />
        <bin index="20" start="0.02" width="0.001" count="179" />
        <bin index="21" start="0.021" width="0.001" count="49" />
        <bin index="22" start="0.022" width="0.001" count="125" />
        <bin index="23" start="0.023" width="0.001" count="56" />
        <bin index="24" start="0.024" width="0.001" count="57" />
        <bin index="25" start="0.025" width="0.001" count="67" />
        <bin index="26" start="0.026" width="0.001" count="50" />
        <bin index="27" start="0.027" width="0.001" count="52" />
        <bin index="28" start="0.028" width="0.001" count="77" />
        <bin index="29" start="0.029" width="0.001" count="457" />
        <bin index="30" start="0.03" width="0.001" count="398" />
        <bin index="31" start="0.031" width="0.001" count="421" />
        <bin index="32" start="0.032" width="0.001" count="360" />
        <bin index="33" start="0.033" width="0.001" count="353" />
        <bin index="34" start="0.034" width="0.001" count="270" />
        <bin index="35" start="0.035" width="0.001" count="290" />
        <bin index="36" start="0.036" width="0.001" count="320" />
        <bin index="37" start="0.037" width="0.001" count="445" />
        <bin index="38" start="0.038" width="0.001" count="339" />
        <bin index="39" start="0.039" width="0.001" count="250" />
        <bin index="40" start="0.04" width="0.001" count="213" />
        <bin index="41" start="0.041" width="0.001" count="275" />
        <bin index="42" start="0.042" width="0.001" count="327" />
        <bin index="44" start="0.044" width="0.001" count="150" />
        <bin index="45" start="0.045" width="0.001" count="138" />
        <bin index="46" start="0.046" width="0.001" count="160" />
        <bin index="47" start="0.047" width="0.001" count="108" />
        <bin index="48" start="0.048" width="0.001" count="103" />
        <bin index="49" start="0.049" width="0.001" count="96" />
        <bin index="50" start="0.05" width="0.001" count="133" />
        <bin index="52" start="0.052" width="0.001" count="70" />
        <bin index="53" start="0.053" width="0.001" count="71" />
        <bin index="54" start="0.054" width="0.001" count="45" />
        <bin index="55" start="0.055" width="0.001" count="22" />
        <bin index="56" start="0.056" width="0.001" count="41" />
        <bin index="57" start="0.057" width="0.001" count="17" />
        <bin index="58" start="0.058" width="0.001" count="57" />
        <bin index="60" start="0.06" width="0.001" count="28" />
        <bin index="61" start="0.061" width="0.001" count="1" />
        <bin index="62" start="0.062" width="0.001" count="13" />
        <bin index="63" start="0.063" width="0.001" count="9" />
        <bin index="64" start="0.064" width="0.001" count="13" />
        <bin index="65" start="0.065" width="0.001" count="4" />
        <bin index="66" start="0.066" width="0.001" count="7" />
        <bin index="67" start="0.067" width="0.001" count="1" />
        <bin index="69" start="0.069" width="0.001" count="3" />
        <bin index="70" start="0.07" width="0.001" count="2" />
        <bin index="72" start="0.072" width="0.001" count="1" />
        <bin index="73" start="0.073" width="0.001" count="3" />
        <bin index="78" start="0.078" width="0.001" count="2" />
      </delayHistogram>

I even try to look for the explanation from flow monitor module paper , but it does not have any context about what start time represents, is it in nano second I assume? and i have found that the sum of count is the total received packets, but I am having a hard time to understand the start because is it in the timeline of entire simulation or just a random interval?

Because I found that I can not plot this histogram properly if I do not fully understand it.

Any suggestion would be really grateful :)

[Tommaso Pecorella]

Mmm... we didn't document it because we thought it was obvious. Perhaps it's not THAT obvious (if one doesn't look at the code).

"start" is the beginning of the bin, in seconds. Translated, the line "<bin index="63" start="0.063" width="0.001" count="9" />" means that 9 packets did experience a delay between 0.063 seconds (included) and 0.064 (excluded).

Since it's a DELAY it doesn't have anything to do with the simulation start or stop time. It's the delay between when the packet was sent and when it was received.