Robust stability analysis of simple control algorithms in communication networks

There is increasing interest in the control of communication networks. This paper reveals that a simple method, the dual-locus diagram method, is very effective in analyzing the robust stability of simple time-delay systems, which are often met in communication systems. As to a single connection studied in [15], the same results as those obtained by Niculescu have been obtained, but in a much simpler and clearer graphical way. As to the web-based control system studied in [2], the results have been extended to a much broader class of systems, i.e. from a line in the parameter plane to the whole plane. The stability region is divided into a delay-dependent stability region and a delay-independent stability region, which offers a nice graphical view on the conservativeness of the delay-independent stability criteria.