SOURCEFORGE » RALF » 2014 ACM testing using channel emulation

h1. Measurement Capabilities

h2. Modems

The Newtec EL470 versions that Telecom Bretagne owns have no protocol testing capabilities. However, when in ACM mode, the ACM controller (the HUB) keeps a log file containing the modulation and coding schemes as well as bitrate and Es/N0 estimates . This is information is stored in a .csv file containing the following:

<pre>

Timestamp,Demod,RqModCod,EsNo,CarrierBitrate

2014-12-12 15:05:19,1,16APSK-2/3,11.20,1445835

2014-12-12 15:05:24,1,16APSK-2/3,10.72,1324072

2014-12-12 15:05:28,1,16APSK-2/3,10.61,1324072

2014-12-12 15:05:31,1,16APSK-2/3,10.66,1324072

2014-12-12 15:05:34,1,8PSK-3/4,10.19,1313479

2014-12-12 15:05:37,1,8PSK-3/4,11.87,1313479

2014-12-12 15:05:41,1,8PSK-3/4,10.40,1313479

2014-12-12 15:06:47,1,QPSK-5/6,6.93,884389

2014-12-12 15:06:51,1,QPSK-5/6,8.18,884389

2014-12-12 15:06:56,1,QPSK-5/6,7.02,825503

</pre>

It is unclear though what the logging frequency is. We have determined that this rate depends on the rate at which Es/N0 estimates change. From the csv file we can extract the following information:

* Timestamp (in seconds)

* Modcod parameter (modulation + coding rate)

* Estimate of E ~s~ / N ~0~

* Information bitrate (in bps)

h2. Traffic generation and capture

In order to measure performance at the application level we will use Iperf. Iperf is a tool to generate streams of TCP and UDP traffic as well as measuring throughput and other statistics. In order to have a finer control over throughput reporting, we will capture all traffic and perform an offline calculation of throughput using #pcaptput.