Congestion Control in ATM networks using PID Controller with Immune Algorithm

In this paper, the Proportional-Integrator-Differentiator (PID) controller is tuned in a rate-based congestion control scheme to be used for the ATM networks. The tuning strategy is based on reformulating the problem to be as an optimization problem with a compact fitness function reflecting the control requirements. The key contribution in this paper is to adopt the immune algorithm as the tuning process, which proves to be so simple, fast, and computationally cheap compared with the other traditional tuning methods. For the purpose of comparison, a simplified network model is built and simulated using two control methods; namely: the proposed control scheme and the well-known single-bit indicator scheme. The experimental results prove that the PID controller tuned by the immune algorithm is superior in terms of the stability of both, buffer occupancy in the switch and the source rate. Both the transient behavior and the steady-state response for the PID controller are shown to be much better than the single-bit indicator scheme. Consequently, the proposed control scheme outperforms the single-bit indicator in terms of link utilization, buffer utilization, packet drop and robustness against any burst change in the network environment.