Less conservative global stability for nonlinear FAST TCP system with time-varying time-delay
非线性时变时滞FAST TCP系统低保守全局稳定性

We investigate the global stability of the nonlinear fast active queue management scalable transmission control protocol (FAST TCP) system with time-varying time-delay. By considering that the time-delay variation is proportional to the sending window variation of the TCP source and the nonlinear function is strictly monotonically decreasing, we present the improved iterative formulas for calculating the trajectory bounds and determining the trajectory bounds of the FAST TCP system in each oscillating period. For the FAST TCP system, we develop a global stability condition which is less conservative than the existing one. The effectiveness of this improved global stability condition is validated by the network simulator 2 (NS-2) simulation results.