Self-tuning multiloop PI rate controller for an MIMO AQM router with interval gain margin assignment

We design a self-tuning multiloop PI (proportional-integral) rate controller for the MIMO (multiple-input multiple-output) AQM (active queue management) router to support best-effort service traffic in the Internet. Unlike the manual trial and error approach, our controller design employs the DNA (direct Nyquist array) method by shaping Gershgorin band analytically, thus allowing users to achieve the good stability robustness of the MIMO AQM control system through assigning proper gain margin interval. The self-tuning multiloop PI rate controller is located in every output port of the MIMO router and can calculate the respective advertised source transmission rates based on the instantaneous queue length of the buffer.