Design of Congestion Control Based on Instantaneous Queue Sizes in the Routers

Recently, explicit Control Protocol (XCP), Rate Control Protocol (RCP), and Adaptive Proportional-Integral Rate Control Protocol (API-RCP) have been proposed for congestion control, with the main objective of achieving fair and maximum bandwidth utilization. However, studies reveal that both RCP and XCP may suffer continuous oscillations due to misestimating the bottleneck link capacity, and API-RCP may experience oscillations because of its PI adaptivity scheme which involves switching nonlinearity. To avoid these problems, in this paper a way of designing congestion control based on the instantaneous queue sizes in the routers is proposed. The new scheme attains high link utilization and smooth dynamics by clamping the bottleneck queue at a desired size. And it maintains good fairness by allocating the bottleneck bandwidth equally to the competing flows. Simulations are performed to verify the effectiveness of the theoretical design.