Anti-windup Compensation in TCP/IP Routers: A Multi-delay Feedback Systems Approach

The design of anti-windup compensators for TCP/IP congestion in the presence of multiple classes of traffic is addressed here: a methodology is presented that takes into account the constraints to achieve the desired queue size, guaranteeing the stability even in the presence of disturbances. Our proposed technique is based on using LMIs that include a tuning parameter, which makes possible to enlarge the domain of attraction to ensure the stability in the varying conditions inherent to TCP/IP traffic. This is so far the first control theory based approach for anti-windup in router that allows multi class Active Queue Management, considering delays, input saturation and variable link bandwidth (modeled as a time-variant disturbance). These characteristics are relevant for framing the network within Service Level Agreements, as data traffic is not homogeneous, and transmission delays are variable.