Using GNU Octave, version 3.6.1
The currently supported version of this framework was written in Python:
https://github.com/c-ilharco-magalhaes/rmcat_evaluation
OBJECTIVES:
The repository aims to provide an octave simulation framework that is easy to read, run and modify. Results visualization helps to get a better understanding on how congestion control algorithms GCC and NADA work. Furthermore, new filters and other algorithm modifications can be tested.
ABOUT:
This framework simulates:
A sender that creates packets, with a pace determined by the sending bitrate and the packet size.
Packets are submitted to:
Delay filter: adds latency - minimum one way path delay.
Choke filter: adds travel time. Packet can be lost if delay > bottleneck queuing size.
Jitter filter: adds noise to the arrival time.
(Those filters simulate effect of the packet traveling through the channel link).
A receiver then gets the packets with updated timestamps.
NADA congestion control algorithm is implemented, according to the internet draft (work in progress):
https://tools.ietf.org/html/draft-ietf-rmcat-nada-00
HOW TO USE:
Calling RunNada(EvaluationTest1()) from Octave will simulate the evaluation test case 5.1, available on:
https://tools.ietf.org/html/draft-ietf-rmcat-eval-test-01#section-5.1
Adjust/tune parameters according to your needs.
Since jitter is always positive, using a min filter instead of a median filter can be a good alternative to measure how much of the delay isn't due to jitter. Travel time depends on the link capacity. A 1200 bytes packet will naturally have a 15ms higher delay over a 500kbps than over a 2500kbps network. This can affect NADA's performance if the capacity drops: the baseline_delay won't be updated. One solution can be update it over a previous time window. Another one can be estimate the current send time.
RESULTS: In a constant 1500 kbps link capacity high jitter scenario, the modified ADA version achieves a significantly higher throughput compared with the original one. The min filter seems to be a good option to reduce jitter sensitiveness.
The modifications to NADA algorithm that were implemented on:
https://chromium.googlesource.com/external/webrtc/+/master/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
were also implemented in this branch.
TODO:
Implement GCC congestion control algorithm on this framework.
Test other filters/classifiers as alternatives to Kalman filter.