Constructive output feedback AQM design

A novel constructive output feedback congestion controller is presented for asymptotically stabilizing a class of TCP networks at a desired operating point. An observer for the TCP window size is proposed to aid the task of designing AQM controller with only the output (queue size) measurement. Conditions under which the TCP window estimation converges to the true window size is related to the persistent excitation (PE) condition of the control input. Observer-based backstepping design technique is applied for developing the control law, in the presence of amplitude limits on the control input-packets dropping or marking ratio must fall between 0 and 1. An estimation of the domain of attractiveness is provided by a Lyapunov level set.